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diff --git a/old/haero10.txt b/old/haero10.txt new file mode 100644 index 0000000..a689fea --- /dev/null +++ b/old/haero10.txt @@ -0,0 +1,14651 @@ +****The Project Gutenberg Etext of A History of Aeronautics**** +by E. Charles Vivian + + +Copyright laws are changing all over the world, be sure to check +the copyright laws for your country before posting these files!! + +Please take a look at the important information in this header. +We encourage you to keep this file on your own disk, keeping an +electronic path open for the next readers. Do not remove this. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**Etexts Readable By Both Humans and By Computers, Since 1971** + +*These Etexts Prepared By Hundreds of Volunteers and Donations* + +Information on contacting Project Gutenberg to get Etexts, and +further information is included below. We need your donations. + + +A History of Aeronautics + +by E. 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Charles Vivian + + + + +FOREWORD + +Although successful heavier-than-air flight is less than two +decades old, and successful dirigible propulsion antedates it by +a very short period, the mass of experiment and accomplishment +renders any one-volume history of the subject a matter of +selection. In addition to the restrictions imposed by space +limits, the material for compilation is fragmentary, and, in +many cases, scattered through periodical and other publications. +Hitherto, there has been no attempt at furnishing a detailed +account of how the aeroplane and the dirigible of to-day came to +being, but each author who has treated the subject has devoted +his attention to some special phase or section. The principal +exception to this rule--Hildebrandt--wrote in 1906, and a good +many of his statements are inaccurate, especially with regard to +heavier-than-air experiment. + +Such statements as are made in this work are, where possible, +given with acknowledgment to the authorities on which they rest. +Further acknowledgment is due to Lieut.-Col. Lockwood Marsh, +not only for the section on aeroplane development which he has +contributed to the work, but also for his kindly assistance and +advice in connection with the section on aerostation. The +author's thanks are also due to the Royal Aeronautical Society +for free access to its valuable library of aeronautical +literature, and to Mr A. Vincent Clarke for permission to make +use of his notes on the development of the aero engine. + +In this work is no claim to originality--it has been a matter +mainly of compilation, and some stories, notably those of the +Wright Brothers and of Santos Dumont, are better told in the +words of the men themselves than any third party could tell +them. The author claims, however, that this is the first +attempt at recording the facts of development and stating, as +fully as is possible in the compass of a single volume, how +flight and aerostation have evolved. The time for a critical +history of the subject is not yet. + +In the matter of illustrations, it has been found very difficult +to secure suitable material. Even the official series of +photographs of aeroplanes in the war period is curiously +incomplete' and the methods of censorship during that period +prevented any complete series being privately collected. +Omissions in this respect will probably be remedied in future +editions of the work, as fresh material is constantly being +located. + +E.C.V. October, 1920. + +CONTENTS +Part I--THE EVOLUTION OF THE AEROPLANE + I. THE PERIOD OF LEGEND + II. EARLY EXPERIMENTS + III. SIR GEORGE CAYLEY--THOMAS WALKER + IV. THE MIDDLE NINETEENTH CENTURY + V. WENHAM, LE BRIS, AND SOME OTHERS + VI. THE AGE OF THE GIANTS + VII. LILIENTHAL AND PILCHER + VIII. AMERICAN GLIDING EXPERIMENTS + IX. NOT PROVEN + X. SAMUEL PIERPOINT LANGLEY + XI. THE WRIGHT BROTHERS + XII. THE FIRST YEARS OF CONQUEST + XIII. FIRST FLIERS IN ENGLAND + XIV. RHEIMS, AND AFTER + XV. THE CHANNEL CROSSING + XVI. LONDON TO MANCHESTER + XVII. A SUMMARY--TO 1911 +XVIII. A SUMMARY--TO 1914 + XIX. THE WAR PERIOD--I + XX. THE WAR PERIOD--II + XXI. RECONSTRUCTION + XXII. 1919-1920 + +Part II--1903-1920: PROGRESS IN DESIGN + I. THE BEGINNINGS + II. MULTIPLICITY OF IDEAS + III. PROGRESS ON STANDARDISED LINES + IV. THE WAR PERIOD + +Part III--AEROSTATICS + I. BEGINNINGS + II. THE FIRST DIRIGIBLES + III. SANTOS-DUMONT + IV. THE MILITARY DIRIGIBLE + V. BRITISH AIRSHIP DESIGN + VI. THE AIRSHIP COMMERCIALLY + VII. KITE BALLOONS + +PART IV--ENGINE DEVELOPMENT + I. THE VERTICAL TYPE + II. THE VEE TYPE + III. THE RADIAL TYPE + IV. THE ROTARY TYPE + V. THE HORIZONTALLY-OPPOSED ENGINE + VI. THE TWO-STROKE CYCLE ENGINE + VII. ENGINES OF THE WAR PERIOD + +APPENDICES + + + +PART I + +THE EVOLUTION OF THE AEROPLANE + +I. THE PERIOD OF LEGEND + +The blending of fact and fancy which men call legend reached its +fullest and richest expression in the golden age of Greece, and +thus it is to Greek mythology that one must turn for the best +form of any legend which foreshadows history. Yet the +prevalence of legends regarding flight, existing in the records +of practically every race, shows that this form of transit was a +dream of many peoples--man always wanted to fly, and imagined +means of flight. + +In this age of steel, a very great part of the inventive genius +of man has gone into devices intended to facilitate transport, +both of men and goods, and the growth of civilisation is in +reality the facilitation of transit, improvement of the means of +communication. He was a genius who first hoisted a sail on a +boat and saved the labour of rowing; equally, he who first +harnessed ox or dog or horse to a wheeled vehicle was a +genius--and these looked up, as men have looked up from the +earliest days of all, seeing that the birds had solved the +problem of transit far more completely than themselves. So it +must have appeared, and there is no age in history in which some +dreamers have not dreamed of the conquest of the air; if the +caveman had left records, these would without doubt have showed +that he, too, dreamed this dream. His main aim, probably, was +self-preservation; when the dinosaur looked round the corner, +the prehistoric bird got out of the way in his usual manner, and +prehistoric manÄ such of him as succeeded in getting out of the +way after his fashion--naturally envied the bird, and concluded +that as lord of creation in a doubtful sort of way he ought to +have equal facilities. He may have tried, like Simon the +Magician, and other early experimenters, to improvise those +facilities; assuming that he did, there is the groundwork of +much of the older legend with regard to men who flew, since, +when history began, legends would be fashioned out of attempts +and even the desire to fly, these being compounded of some small +ingredient of truth and much exaggeration and addition. + +In a study of the first beginnings of the art, it is worth while +to mention even the earliest of the legends and traditions, for +they show the trend of men's minds and the constancy of this +dream that has become reality in the twentieth century. In one +of the oldest records of the world, the Indian classic +Mahabarata, it is stated that 'Krishna's enemies sought the aid +of the demons, who built an aerial chariot with sides of iron +and clad with wings. The chariot was driven through the sky till +it stood over Dwarakha, where Krishna's followers dwelt, and +from there it hurled down upon the city missiles that destroyed +everything on which they fell.' Here is pure fable, not legend, +but still a curious forecast of twentieth century bombs from a +rigid dirigible. It is to be noted in this case, as in many, +that the power to fly was an attribute of evil, not of good--it +was the demons who built the chariot, even as at Friedrichshavn. +Mediaeval legend in nearly every cas,attributes flight to the +aid of evil powers, and incites well-disposed people to stick to +the solid earth--though, curiously enough, the pioneers of +medieval times were very largely of priestly type, as witness +the monk of Malmesbury. + +The legends of the dawn of history, however, distribute the +power of flight with less of prejudice. Egyptian sculpture gives +the figure of winged men; the British Museum has made the winged +Assyrian bulls familiar to many, and both the cuneiform records +of Assyria and the hieroglyphs of Egypt record flights that in +reality were never made. The desire fathered the story then, +and until Clement Ader either hopped with his Avion, as is +persisted by his critics, or flew, as is claimed by his friends. + +While the origin of many legends is questionable, that of others +is easy enough to trace, though not to prove. Among the +credulous the significance of the name of a people of Asia +Minor, the Capnobates, 'those who travel by smoke,' gave rise to +the assertion that Montgolfier was not first in the field--or +rather in the air--since surely this people must have been +responsible for the first hot-air balloons. Far less +questionable is the legend of Icarus, for here it is possible to +trace a foundation of fact in the story. Such a tribe as +Daedalus governed could have had hardly any knowledge of the +rudiments of science, and even their ruler, seeing how easy it +is for birds to sustain themselves in the air, might be excused +for believing that he, if he fashioned wings for himself, could +use them. In that belief, let it be assumed, Daedalus made his +wings; the boy, Icarus, learning that his father had determined +on an attempt at flight secured the wings and fastened them to +his own shoulders. A cliff seemed the likeliest place for a +'take-off,' and Icarus leaped from the cliff edge only to find +that the possession of wings was not enough to assure flight to +a human being. The sea that to this day bears his name +witnesses that he made the attempt and perished by it. + +In this is assumed the bald story, from which might grow the +legend of a wise king who ruled a peaceful people--'judged, +sitting in the sun,' as Browning has it, and fashioned for +himself wings with which he flew over the sea and where he +would, until the prince, Icarus, desired to emulate him. +Icarus, fastening the wings to his shoulders with wax, was so +imprudent as to fly too near the sun, when the wax melted and he +fell, to lie mourned of water-nymphs on the shores of waters +thenceforth Icarian. Between what we have assumed to be the +base of fact, and the legend which has been invested with such +poetic grace in Greek story, there is no more than a century or +so of re-telling might give to any event among a people so +simple and yet so given to imagery. + +We may set aside as pure fable the stories of the winged horse +of Perseus, and the flights of Hermes as messenger of the gods. +With them may be placed the story of Empedocles, who failed to +take Etna seriously enough, and found himself caught by an +eruption while within the crater, so that, flying to safety in +some hurry, he left behind but one sandal to attest that he had +sought refuge in space--in all probability, if he escaped at +all, he flew, but not in the sense that the aeronaut understands +it. But, bearing in mind the many men who tried to fly in +historic times, the legend of Icarus and Daedalus, in spite of +the impossible form in which it is presented, may rank with the +story of the Saracen of Constantinople, or with that of Simon +the Magician. A simple folk would naturally idealise the man +and magnify his exploit, as they magnified the deeds of some +strong man to make the legends of Hercules, and there, +full-grown from a mere legend, is the first record of a pioneer +of flying. Such a theory is not nearly so fantastic as that +which makes the Capnobates, on the strength of their name, the +inventors of hot-air balloons. However it may be, both in story +and in picture, Icarus and his less conspicuous father have +inspired the Caucasian mind, and the world is the richer for +them. + +Of the unsupported myths--unsupported, that is, by even a shadow +of probability--there is no end. Although Latin legend +approaches nearer to fact than the Greek in some cases, in +others it shows a disregard for possibilities which renders it +of far less account. Thus Diodorus of Sicily relates that one +Abaris travelled round the world on an arrow of gold, and +Cassiodorus and Glycas and their like told of mechanical birds +that flew and sang and even laid eggs. More credible is the +story of Aulus Gellius, who in his Attic Nights tells how +Archytas, four centuries prior to the opening of the Christian +era, made a wooden pigeon that actually flew by means of a +mechanism of balancing weights and the breath of a mysterious +spirit hidden within it. There may yet arise one credulous +enough to state that the mysterious spirit was precursor of the +internal combustion engine, but, however that may be, the pigeon +of Archytas almost certainly existed, and perhaps it actually +glided or flew for short distances--or else Aulus Gellius was an +utter liar, like Cassiodorus and his fellows. In far later +times a certain John Muller, better known as Regiomontanus, is +stated to have made an artificial eagle which accompanied +Charles V. on his entry to and exit from Nuremberg, flying above +the royal procession. But, since Muller died in 1436 and +Charles was born in 1500, Muller may be ruled out from among the +pioneers of mechanical flight, and it may be concluded that the +historian of this event got slightly mixed in his dates. + +Thus far, we have but indicated how one may draw from the +richest stores from which the Aryan mind draws inspiration, the +Greek and Latin mythologies and poetic adaptations of history. +The existing legends of flight, however, are not thus to be +localised, for with two possible exceptions they belong to all +the world and to every civilisation, however primitive. The two +exceptions are the Aztec and the Chinese; regarding the first of +these, the Spanish conquistadores destroyed such civilisation as +existed in Tenochtitlan so thoroughly that, if legend of flight +was among the Aztec records, it went with the rest; as to the +Chinese, it is more than passing strange that they, who claim to +have known and done everything while the first of history was +shaping, even to antedating the discovery of gunpowder that was +not made by Roger Bacon, have not yet set up a claim to +successful handling of a monoplane some four thousand years ago, +or at least to the patrol of the Gulf of Korea and the Mongolian +frontier by a forerunner of the 'blimp.' + +The Inca civilisation of Peru yields up a myth akin to that of +Icarus, which tells how the chieftain Ayar Utso grew wings and +visited the sun--it was from the sun, too, that the founders of +the Peruvian Inca dynasty, Manco Capac and his wife Mama Huella +Capac, flew to earth near Lake Titicaca, to make the only +successful experiment in pure tyranny that the world has ever +witnessed. Teutonic legend gives forth Wieland the Smith, who +made himself a dress with wings and, clad in it, rose and +descended against the wind and in spite of it. Indian mythology, +in addition to the story of the demons and their rigid dirigible, +already quoted, gives the story of Hanouam, who fitted himself +with wings by means of which he sailed in the air and, according +to his desire, landed in the sacred Lauka. Bladud, the ninth +king of Britain, is said to have crowned his feats of wizardry by +making himself wings and attempting to fly--but the effort cost +him a broken neck. Bladud may have been as mythic as Uther, and +again he may have been a very early pioneer. The Finnish epic, +'Kalevala,' tells how Ilmarinen the Smith 'forged an eagle of +fire,' with 'boat's walls between the wings,' after which he +'sat down on the bird's back and bones,' and flew. + +Pure myths, these, telling how the desire to fly was +characteristic of every age and every people, and how, from time +to time, there arose an experimenter bolder than his fellows, +who made some attempt to translate desire into achievement. And +the spirit that animated these pioneers, in a time when things +new were accounted things accursed, for the most part, has found +expression in this present century in the utter daring and +disregard of both danger and pain that stamps the flying man, a +type of humanity differing in spirit from his earthbound fellows +as fully as the soldier differs from the priest. + +Throughout mediaeval times, records attest that here and there +some man believed in and attempted flight, and at the same +time it is clear that such were regarded as in league with the +powers of evil. There is the half-legend, half-history of +Simon the Magician, who, in the third year of the reign of Nero +announced that he would raise himself in the air, in order to +assert his superiority over St Paul. The legend states that by +the aid of certain demons whom he had prevailed on to assist +him, he actually lifted himself in the air-- but St Paul prayed +him down again. He slipped through the claws of the demons and +fell headlong on the Forum at Rome, breaking his neck. The +'demons' may have been some primitive form of hot-air balloon, +or a glider with which the magician attempted to rise into the +wind; more probably, however, Simon threatened to ascend and +made the attempt with apparatus as unsuitable as Bladud's wings, +paying the inevitable penalty. Another version of the story +gives St Peter instead of St Paul as the one whose prayers +foiled Simon --apart from the identity of the apostle, the two +accounts are similar, and both define the attitude of the age +toward investigation and experiment in things untried. + +Another and later circumstantial story, with similar evidence of +some fact behind it, is that of the Saracen of Constantinople, +who, in the reign of the Emperor Comnenus--some little time +before Norman William made Saxon Harold swear away his crown on +the bones of the saints at Rouen--attempted to fly round the +hippodrome at Constantinople, having Comnenus among the great +throng who gathered to witness the feat. The Saracen chose for +his starting-point a tower in the midst of the hippodrome, and +on the top of the tower he stood, clad in a long white robe which +was stiffened with rods so as to spread and catch the breeze, +waiting for a favourable wind to strike on him. The wind was so +long in coming that the spectators grew impatient. 'Fly, O +Saracen!' they called to him. 'Do not keep us waiting so long +while you try the wind!' Comnenus, who had present with him the +Sultan of the Turks, gave it as his opinion that the experiment +was both dangerous and vain, and, possibly in an attempt to +controvert such statement, the Saracen leaned into the wind and +'rose like a bird 'at the outset. But the record of Cousin, who +tells the story in his Histoire de Constantinople, states that +'the weight of his body having more power to drag him down than +his artificial wings had to sustain him, he broke his bones, and +his evil plight was such that he did not long survive.' + +Obviously, the Saracen was anticipating Lilienthal and his +gliders by some centuries; like Simon, a genuine +experimenter--both legends bear the impress of fact supporting +them. Contemporary with him, and belonging to the history +rather than the legends of flight, was Oliver, the monk of +Malmesbury, who in the year 1065 made himself wings after the +pattern of those supposed to have been used by Daedalus, +attaching them to his hands and feet and attempting to fly with +them. Twysden, in his Historiae Anglicanae Scriptores X, sets +forth the story of Oliver, who chose a high tower as his +starting-point, and launched himself in the air. As a matter of +course, he fell, permanently injuring himself, and died some +time later. + +After these, a gap of centuries, filled in by impossible stories +of magical flight by witches, wizards, and the like--imagination +was fertile in the dark ages, but the ban of the church was on +all attempt at scientific development, especially in such a +matter as the conquest of the air. Yet there were observers of +nature who argued that since birds could raise themselves by +flapping their wings, man had only to make suitable wings, flap +them, and he too would fly. As early as the thirteenth century +Roger Bacon, the scientific friar of unbounded inquisitiveness +and not a little real genius, announced that there could be made +'some flying instrument, so that a man sitting in the middle and +turning some mechanism may put in motion some artificial wings +which may beat the air like a bird flying.' But being a cautious +man, with a natural dislike for being burnt at the stake as a +necromancer through having put forward such a dangerous theory, +Roger added, 'not that I ever knew a man who had such an +instrument, but I am particularly acquainted with the man who +contrived one.' This might have been a lame defence if Roger had +been brought to trial as addicted to black arts; he seems to +have trusted to the inadmissibility of hearsay evidence. + +Some four centuries later there was published a book entitled +Perugia Augusta, written by one C. Crispolti of Perugia--the +date of the work in question is 1648. In it is recorded that +'one day, towards the close of the fifteenth century, whilst +many of the principal gentry had come to Perugia to honour the +wedding of Giovanni Paolo Baglioni, and some lancers were riding +down the street by his palace, Giovanni Baptisti Danti +unexpectedly and by means of a contrivance of wings that he had +constructed proportionate to the size of his body took off from +the top of a tower near by, and with a horrible hissing sound +flew successfully across the great Piazza, which was densely +crowded. But (oh, horror of an unexpected accident!) he had +scarcely flown three hundred paces on his way to a certain point +when the mainstay of the left wing gave way, and, being unable to +support himself with the right alone, he fell on a roof and was +injured in consequence. Those who saw not only this flight, but +also the wonderful construction of the framework of the wings, +said--and tradition bears them out--that he several times flew +over the waters of Lake Thrasimene to learn how he might +gradually come to earth. But, notwithstanding his great genius, +he never succeeded.' + +This reads circumstantially enough, but it may be borne in mind +that the date of writing is more than half a century later than +the time of the alleged achievement--the story had had time to +round itself out. Danti, however, is mentioned by a number of +writers, one of whom states that the failure of his experiment +was due to the prayers of some individual of a conservative turn +of mind, who prayed so vigorously that Danti fell appropriately +enough on a church and injured himself to such an extent as to +put an end to his flying career. That Danti experimented, there +is little doubt, in view of the volume of evidence on the point, +but the darkness of the Middle Ages hides the real truth as to +the results of his experiments. If he had actually flown over +Thrasimene, as alleged, then in all probability both Napoleon +and Wellington would have had air scouts at Waterloo. + +Danti's story may be taken as fact or left as fable, and with it +the period of legend or vague statement may be said to end--the +rest is history, both of genuine experimenters and of +charlatans. Such instances of legend as are given here are not a +tithe of the whole, but there is sufficient in the actual history +of flight to bar out more than this brief mention of the legends, +which, on the whole, go farther to prove man's desire to fly than +his study and endeavour to solve the problems of the air. + + + +II. EARLY EXPERIMENTS + +So far, the stories of the development of flight are either +legendary or of more or less doubtful authenticity, even +including that of Danti, who, although a man of remarkable +attainments in more directions than that of attempted flight, +suffers--so far as reputation is concerned--from the +inexactitudes of his chroniclers; he may have soared over +Thrasimene, as stated, or a mere hop with an ineffectual glider +may have grown with the years to a legend of gliding flight. So +far, too, there is no evidence of the study that the conquest of +the air demanded; such men as made experiments either launched +themselves in the air from some height with made-up wings or +other apparatus, and paid the penalty, or else constructed some +form of machine which would not leave the earth, and then gave +up. Each man followed his own way, and there was no +attempt--without the printing press and the dissemination of +knowledge there was little possibility of attempt--on the part +of any one to benefit by the failures of others. + +Legend and doubtful history carries up to the fifteenth century, +and then came Leonardo da Vinci, first student of flight whose +work endures to the present day. The world knows da Vinci as +artist; his age knew him as architect, engineer, artist, and +scientist in an age when science was a single study, comprising +all knowledge from mathematics to medicine. He was, of course, +in league with the devil, for in no other way could his range of +knowledge and observation be explained by his contemporaries; he +left a Treatise on the Flight of Birds in which are statements +and deductions that had to be rediscovered when the Treatise had +been forgotten--da Vinci anticipated modern knowledge as Plato +anticipated modern thought, and blazed the first broad trail +toward flight. + +One Cuperus, who wrote a Treatise on the Excellence of Man, +asserted that da Vinci translated his theories into practice, +and actually flew, but the statement is unsupported. That he +made models, especially on the helicopter principle, is past +question; these were made of paper and wire, and actuated by +springs of steel wire, which caused them to lift themselves in +the air. It is, however, in the theories which he put forward +that da Vinci's investigations are of greatest interest; these +prove him a patient as well as a keen student of the principles +of flight, and show that his manifold activities did not prevent +him from devoting some lengthy periods to observations of bird +flight. + +'A bird,' he says in his Treatise, 'is an instrument working +according to mathematical law, which instrument it is within the +capacity of man to reproduce with all its movements, but not +with a corresponding degree of strength, though it is deficient +only in power of maintaining equilibrium. We may say, +therefore, that such an instrument constructed by man is lacking +in nothing except the life of the bird, and this life must needs +be supplied from that of man. The life which resides in the +bird's members will, without doubt, better conform to their needs +than will that of a man which is separated from them, and +especially in the almost imperceptible movements which produce +equilibrium. But since we see that the bird is equipped for many +apparent varieties of movement, we are able from this experience +to deduce that the most rudimentary of these movements will be +capable of being comprehended by man's understanding, and that he +will to a great extent be able to provide against the destruction +of that instrument of which he himself has become the living +principle and the propeller.' + +In this is the definite belief of da Vinci that man is capable +of flight, together with a far more definite statement of the +principles by which flight is to be achieved than any which had +preceded it--and for that matter, than many that have succeeded +it. Two further extracts from his work will show the exactness +of his observations:-- + +'When a bird which is in equilibrium throws the centre of +resistance of the wings behind the centre of gravity, then such +a bird will descend with its head downward. This bird which +finds itself in equilibrium shall have the centre of resistance +of the wings more forward than the bird's centre of gravity; +then such a bird will fall with its tail turned toward the +earth.' + +And again: 'A man, when flying, shall be free from the waist +up, that he may be able to keep himself in equilibrium as he +does in a boat, so that the centre of his gravity and of the +instrument may set itself in equilibrium and change when +necessity requires it to the changing of the centre of its +resistance.' + +Here, in this last quotation, are the first beginnings of the +inherent stability which proved so great an advance in design, +in this twentieth century. But the extracts given do not begin +to exhaust the range of da Vinci's observations and deductions. +With regard to bird flight, he observed that so long as a bird +keeps its wings outspread it cannot fall directly to earth, but +must glide down at an angle to alight--a small thing, now that +the principle of the plane in opposition to the air is generally +grasped, but da Vinci had to find it out. From observation he +gathered how a bird checks its own speed by opposing tail and +wing surface to the direction of flight, and thus alights at the +proper 'landing speed.' He proved the existence of upward air +currents by noting how a bird takes off from level earth with +wings outstretched and motionless, and, in order to get an +efficient substitute for the natural wing, he recommended that +there be used something similar to the membrane of the wing of a +bat--from this to the doped fabric of an aeroplane wing is but +a small step, for both are equally impervious to air. Again, da +Vinci recommended that experiments in flight be conducted at a +good height from the ground, since, if equilibrium be lost +through any cause, the height gives time to regain it. This +recommendation, by the way, received ample support in the +training areas of war pilots. + +Man's muscles, said da Vinci, are fully sufficient to enable him +to fly, for the larger birds, he noted, employ but a small part +of their strength in keeping themselves afloat in the air--by +this theory he attempted to encourage experiment, just as, when +his time came, Borelli reached the opposite conclusion and +discouraged it. That Borelli was right--so far--and da Vinci +wrong, detracts not at all from the repute of the earlier +investigator, who had but the resources of his age to support +investigations conducted in the spirit of ages after. + +His chief practical contributions to the science of +flight--apart from numerous drawings which have still a +value--are the helicopter or lifting screw, and the parachute. +The former, as already noted, he made and proved effective in +model form, and the principle which he demonstrated is that of +the helicopter of to-day, on which sundry experimenters work +spasmodically, in spite of the success of the plane with its +driving propeller. As to the parachute, the idea was doubtless +inspired by observation of the effect a bird produced by +pressure of its wings against the direction of flight. + +Da Vinci's conclusions, and his experiments, were forgotten +easily by most of his contemporaries; his Treatise lay forgotten +for nearly four centuries, overshadowed, mayhap, by his other +work. There was, however, a certain Paolo Guidotti of Lucca, +who lived in the latter half of the sixteenth century, and who +attempted to carry da Vinci's theories--one of them, at least, +into practice. For this Guidotti, who was by profession an +artist and by inclination an investigator, made for himself +wings, of which the framework was of whalebone; these he covered +with feathers, and with them made a number of gliding flights, +attaining considerable proficiency. He is said in the end to +have made a flight of about four hundred yards, but this attempt +at solving the problem ended on a house roof, where Guidotti +broke his thigh bone. After that, apparently, he gave up the +idea of flight, and went back to painting. + +One other a Venetian architect named Veranzio. studied da +Vinci's theory of the parachute, and found it correct, if +contemporary records and even pictorial presentment are correct. +Da Vinci showed his conception of a parachute as a sort of +inverted square bag; Veranzio modified this to a 'sort of square +sail extended by four rods of equal size and having four cords +attached at the corners,' by means of which 'a man could without +danger throw himself from the top of a tower or any high place. +For though at the moment there may be no wind, yet the effort of +his falling will carry up the wind, which the sail will hold, by +which means he does not fall suddenly but descends little by +little. The size of the sail should be measured to the man.' By +this last, evidently, Veranzio intended to convey that the sheet +must be of such content as would enclose sufficient air to +support the weight of the parachutist. + +Veranzio made his experiments about 1617-1618, but, naturally, +they carried him no farther than the mere descent to earth, and +since a descent is merely a descent, it is to be conjectured that +he soon got tired of dropping from high roofs, and took to +designing architecture instead of putting it to such a use. With +the end of his experiments the work of da Vinci in relation to +flying became neglected for nearly four centuries. + +Apart from these two experimenters, there is little to record in +the matter either of experiment or study until the seventeenth +century. Francis Bacon, it is true, wrote about flying in his +Sylva Sylvarum, and mentioned the subject in the New Atlantis, +but, except for the insight that he showed even in superficial +mention of any specific subject, he does not appear to have made +attempt at serious investigation. 'Spreading of Feathers, thin +and close and in great breadth will likewise bear up a great +Weight,' says Francis, 'being even laid without Tilting upon the +sides.' But a lesser genius could have told as much, even in +that age, and though the great Sir Francis is sometimes adduced +as one of the early students of the problems of flight, his +writings will not sustain the reputation. + +The seventeenth century, however, gives us three names, those of +Borelli, Lana, and Robert Hooke, all of which take definite +place in the history of flight. Borelli ranks as one of the +great figures in the study of aeronautical problems, in spite of +erroneous deductions through which he arrived at a purely +negative conclusion with regard to the possibility of human +flight. + +Borelli was a versatile genius. Born in 1608, he was +practically contemporary with Francesco Lana, and there is +evidence that he either knew or was in correspondence with many +prominent members of the Royal Society of Great Britain, more +especially with John Collins, Dr Wallis, and Henry Oldenburgh, +the then Secretary of the Society. He was author of a long list +of scientific essays, two of which only are responsible for his +fame, viz., Theorice Medicaearum Planetarum, published in +Florence, and the better known posthumous De Motu Animalium. The +first of these two is an astronomical study in which Borelli +gives evidence of an instinctive knowledge of gravitation, +though no definite expression is given of this. The second +work, De Motu Animalium, deals with the mechanical action of +the limbs of birds and animals and with a theory of the action +of the internal organs. A section of the first part of this +work, called De Volatu, is a study of bird flight; it is quite +independent of Da Vinci's earlier work, which had been forgotten +and remained unnoticed until near on the beginning of practical +flight. + +Marey, in his work, La Machine Animale, credits Borelli with the +first correct idea of the mechanism of flight. He says: +'Therefore we must be allowed to render to the genius of Borelli +the justice which is due to him, and only claim for ourselves +the merit of having furnished the experimental demonstration of +a truth already suspected.' In fact, all subsequent studies on +this subject concur in making Borelli the first investigator who +illustrated the purely mechanical theory of the action of a +bird's wings. + +Borelli's study is divided into a series of propositions in +which he traces the principles of flight, and the mechanical +actions of the wings of birds. The most interesting of these +are the propositions in which he sets forth the method in which +birds move their wings during flight and the manner in which the +air offers resistance to the stroke of the wing. With regard to +the first of these two points he says: 'When birds in repose +rest on the earth their wings are folded up close against their +flanks, but when wishing to start on their flight they first +bend their legs and leap into the air. Whereupon the joints of +their wings are straightened out to form a straight line at +right angles to the lateral surface of the breast, so that the +two wings, outstretched, are placed, as it were, like the arms +of a cross to the body of the bird. Next, since the wings with +their feathers attached form almost a plane surface, they are +raised slightly above the horizontal, and with a most quick +impulse beat down in a direction almost perpendicular to the +wing-plane, upon the underlying air; and to so intense a beat +the air, notwithstanding it to be fluid, offers resistance, +partly by reason of its natural inertia, which seeks to retain +it at rest, and partly because the particles of the air, +compressed by the swiftness of the stroke, resist this +compression by their elasticity, just like the hard ground. +Hence the whole mass of the bird rebounds, making a fresh leap +through the air; whence it follows that flight is simply a +motion composed of successive leaps accomplished through the +air. And I remark that a wing can easily beat the air in a +direction almost perpendicular to its plane surface, although +only a single one of the corners of the humerus bone is attached +to the scapula, the whole extent of its base remaining free and +loose, while the greater transverse feathers are joined to the +lateral skin of the thorax. Nevertheless the wing can easily +revolve about its base like unto a fan. Nor are there lacking +tendon ligaments which restrain the feathers and prevent them +from opening farther, in the same fashion that sheets hold in +the sails of ships. No less admirable is nature's cunning in +unfolding and folding the wings upwards, for she folds them not +laterally, but by moving upwards edgewise the osseous parts +wherein the roots of the feathers are inserted; for thus, +without encountering the air's resistance the upward motion of +the wing surface is made as with a sword, hence they can be +uplifted with but small force. But thereafter when the wings +are twisted by being drawn transversely and by the resistance of +the air, they are flattened as has been declared and will be +made manifest hereafter.' + +Then with reference to the resistance to the air of the wings he +explains: 'The air when struck offers resistance by its elastic +virtue through which the particles of the air compressed by the +wing-beat strive to expand again. Through these two causes of +resistance the downward beat of the wing is not only opposed, +but even caused to recoil with a reflex movement; and these two +causes of resistance ever increase the more the down stroke of +the wing is maintained and accelerated. On the other hand, the +impulse of the wing is continuously diminished and weakened by +the growing resistance. Hereby the force of the wing and the +resistance become balanced; so that, manifestly, the air is +beaten by the wing with the same force as the resistance to the +stroke.' + +He concerns himself also with the most difficult problem that +confronts the flying man of to-day, namely, landing effectively, +and his remarks on this subject would be instructive even to an +air pilot of these days: 'Now the ways and means by which the +speed is slackened at the end of a flight are these. The bird +spreads its wings and tail so that their concave surfaces are +perpendicular to the direction of motion; in this way, the +spreading feathers, like a ship's sail, strike against the still +air, check the speed, and so that most of the impetus may be +stopped, the wings are flapped quickly and strongly forward, +inducing a contrary motion, so that the bird absolutely or very +nearly stops.' + +At the end of his study Borelli came to a conclusion which +militated greatly against experiment with any heavier-than-air +apparatus, until well on into the nineteenth century, for having +gone thoroughly into the subject of bird flight he states +distinctly in his last proposition on the subject that 'It is +impossible that men should be able to fly craftily by their own +strength.' This statement, of course, remains true up to the +present day for no man has yet devised the means by which he can +raise himself in the air and maintain himself there by mere +muscular effort. + +From the time of Borelli up to the development of the steam +engine it may be said that flight by means of any +heavier-than-air apparatus was generally regarded as impossible, +and apart from certain deductions which a little experiment +would have shown to be doomed to failure, this method of flight +was not followed up. It is not to be wondered at, when +Borelli's exaggerated estimate of the strength expended by birds +in proportion to their weight is borne in mind; he alleged that +the motive force in birds' wings is 10,000 times greater than +the resistance of their weight, and with regard to human flight +he remarks:-- + +'When, therefore, it is asked whether men may be able to fly by +their own strength, it must be seen whether the motive power of +the pectoral muscles (the strength of which is indicated and +measured by their size) is proportionately great, as it is +evident that it must exceed the resistance of the weight of the +whole human body 10,000 times, together with the weight of +enormous wings which should be attached to the arms. And it is +clear that the motive power of the pectoral muscles in men is +much less than is necessary for flight, for in birds the bulk and +weight of the muscles for flapping the wings are not less than a +sixth part of the entire weight of the body. Therefore, it would +be necessary that the pectoral muscles of a man should weigh +more than a sixth part of the entire weight of his body; so also +the arms, by flapping with the wings attached, should be able to +exert a power 10,000 times greater than the weight of the human +body itself. But they are far below such excess, for the +aforesaid pectoral muscles do not equal a hundredth part of the +entire weight of a man. Wherefore either the strength of the +muscles ought to be increased or the weight of the human body +must be decreased, so that the same proportion obtains in it as +exists in birds. Hence it is deducted that the Icarian +invention is entirely mythical because impossible, for it is not +possible either to increase a man's pectoral muscles or to +diminish the weight of the human body; and whatever apparatus is +used, although it is possible to increase the momentum, the +velocity or the power employed can never equal the resistance; +and therefore wing flapping by the contraction of muscles cannot +give out enough power to carry up the heavy body of a man.' + +It may be said that practically all the conclusions which +Borelli reached in his study were negative. Although +contemporary with Lana, he perceived the one factor which +rendered Lana's project for flight by means of vacuum globes an +impossibility--he saw that no globe could be constructed +sufficiently light for flight, and at the same time sufficiently +strong to withstand the pressure of the outside atmosphere. He +does not appear to have made any experiments in flying on his +own account, having, as he asserts most definitely, no faith in +any invention designed to lift man from the surface of the +earth. But his work, from which only the foregoing short +quotations can be given, is, nevertheless, of indisputable +value, for he settled the mechanics of bird flight, and paved +the way for those later investigators who had, first, the steam +engine, and later the internal combustion engine--two factors in +mechanical flight which would have seemed as impossible to +Borelli as would wireless telegraphy to a student of Napoleonic +times. On such foundations as his age afforded Borelli built +solidly and well, so that he ranks as one of the greatest--if +not actually the greatest--of the investigators into this +subject before the age of steam. + +The conclusion, that 'the motive force in birds' wings is +apparently ten thousand times greater than the resistance of +their weight,' is erroneous, of course, but study of the +translation from which the foregoing excerpt is taken will show +that the error detracts very little from the value of the work +itself. Borelli sets out very definitely the mechanism of +flight, in such fashion that he who runs may read. His +reference to 'the use of a large vessel,' etc., concerns the +suggestion made by Francesco Lana, who antedated Borelli's +publication of De Motu Animalium by some ten years with his +suggestion for an 'aerial ship,' as he called it. Lana's mind +shows, as regards flight, a more imaginative twist; Borelli +dived down into first causes, and reached mathematical +conclusions; Lana conceived a theory and upheld it-- +theoretically, since the manner of his life precluded experiment. + +Francesco Lana, son of a noble family, was born in 1631; in 1647 +he was received as a novice into the Society of Jesus at Rome, +and remained a pious member of the Jesuit society until the end +of his life. He was greatly handicapped in his scientific +investigations by the vows of poverty which the rules of the +Order imposed on him. He was more scientist than priest all his +life; for two years he held the post of Professor of Mathematics +at Ferrara, and up to the time of his death, in 1687, he spent +by far the greater part of his time in scientific research, He +had the dubious advantage of living in an age when one man could +cover the whole range of science, and this he seems to have done +very thoroughly. There survives an immense work of his entitled, +Magisterium Naturae et Artis, which embraces the whole field of +scientific knowledge as that was developed in the period in +which Lana lived. In an earlier work of his, published in +Brescia in 1670, appears his famous treatise on the aerial ship, +a problem which Lana worked out with thoroughness. He was +unable to make practical experiments, and thus failed to +perceive the one insuperable drawback to his project--of which +more anon. + +Only extracts from the translation of Lana's work can be given +here, but sufficient can be given to show fully the means by +which he designed to achieve the conquest of the air. He begins +by mention of the celebrated pigeon of Archytas the Philosopher, +and advances one or two theories with regard to the way in which +this mechanical bird was constructed, and then he recites, +apparently with full belief in it, the fable of Regiomontanus +and the eagle that he is said to have constructed to accompany +Charles V. on his entry into Nuremberg. In fact, Lana starts +his work with a study of the pioneers of mechanical flying up to +his own time, and then outlines his own devices for the +construction of mechanical birds before proceeding to detail the +construction of the aerial ship. Concerning primary experiments +for this he says:-- + +'I will, first of all, presuppose that air has weight owing to +the vapours and halations which ascend from the earth and seas +to a height of many miles and surround the whole of our +terraqueous globe; and this fact will not be denied by +philosophers, even by those who may have but a superficial +knowledge. because it can be proven by exhausting, if not all, +at any rate the greater part of, the air contained in a glass +vessel, which, if weighed before and after the air has been +exhausted, will be found materially reduced in weight. Then I +found out how much the air weighed in itself in the following +manner. I procured a large vessel of glass, whose neck could be +closed or opened by means of a tap, and holding it open I warmed +it over a fire, so that the air inside it becoming rarified, the +major part was forced out; then quickly shutting the tap to +prevent the re-entry I weighed it; which done, I plunged its +neck in water, resting the whole of the vessel on the surface of +the water, then on opening the tap the water rose in the vessel +and filled the greater part of it. I lifted the neck out of the +water, released the water contained in the vessel, and measured +and weighed its quantity and density, by which I inferred that a +certain quantity of air had come out of the vessel equal in bulk +to the quantity of water which had entered to refill the portion +abandoned by the air. I again weighed the vessel, after I had +first of all well dried it free of all moisture, and found it +weighed one ounce more whilst it was full of air than when it +was exhausted of the greater part, so that what it weighed more +was a quantity of air equal in volume to the water which took +its place. The water weighed 640 ounces, so I concluded that +the weight of air compared with that of water was 1 to 640--that +is to say, as the water which filled the vessel weighed 640 +ounces, so the air which filled the same vessel weighed one +ounce.' + +Having thus detailed the method of exhausting air from a vessel, +Lana goes on to assume that any large vessel can be entirely +exhausted of nearly all the air contained therein. Then he +takes Euclid's proposition to the effect that the superficial +area of globes increases in the proportion of the square of the +diameter, whilst the volume increases in the proportion of the +cube of the same diameter, and he considers that if one only +constructs the globe of thin metal, of sufficient size, and +exhausts the air in the manner that he suggests, such a globe +will be so far lighter than the surrounding atmosphere that it +will not only rise, but will be capable of lifting weights. +Here is Lana's own way of putting it:-- + +'But so that it may be enabled to raise heavier weights and to +lift men in the air, let us take double the quantity of copper, +1,232 square feet, equal to 308 lbs. of copper; with this double +quantity of copper we could construct a vessel of not only +double the capacity, but of four times the capacity of the +first, for the reason shown by my fourth supposition. +Consequently the air contained in such a vessel will be 718 lbs. +4 2/3 ounces, so that if the air be drawn out of the vessel it +will be 410 lbs. 4 2/3 ounces lighter than the same volume of +air, and, consequently, will be enabled to lift three men, or at +least two, should they weigh more than eight pesi each. It is +thus manifest that the larger the ball or vessel is made, the +thicker and more solid can the sheets of copper be made, because, +although the weight will increase, the capacity of the vessel +will increase to a greater extent and with it the weight of the +air therein, so that it will always be capable to lift a heavier +weight. From this it can be easily seen how it is possible to +construct a machine which, fashioned like unto a ship, will float +on the air.' + +With four globes of these dimensions Lana proposed to make an +aerial ship of the fashion shown in his quaint illustration. He +is careful to point out a method by which the supporting globes +for the aerial ship may be entirely emptied of air; this is to +be done by connecting to each globe a tube of copper which is +'at least a length of 47 modern Roman palm).' A small tap is to +close this tube at the end nearest the globe, and then vessel +and tube are to be filled with water, after which the tube is to +be immersed in water and the tap opened, allowing the water to +run out of the vessel, while no air enters. The tap is then +closed before the lower end of the tube is removed from the +water, leaving no air at all in the globe or sphere. Propulsion +of this airship was to be accomplished by means of sails, and +also by oars. + +Lana antedated the modern propeller, and realised that the air +would offer enough resistance to oars or paddle to impart motion +to any vessel floating in it and propelled by these means, +although he did not realise the amount of pressure on the air +which would be necessary to accomplish propulsion. As a matter +of fact, he foresaw and provided against practically all the +difficulties that would be encountered in the working, as well +as the making, of the aerial ship, finally coming up against +what his religious training made an insuperable objection. +This, again, is best told in his own words:-- + +'Other difficulties I do not foresee that could prevail against +this invention, save one only, which to me seems the greatest of +them all, and that is that God would surely never allow such a +machine to be successful, since it would create many +disturbances in the civil and political governments of mankind.' + +He ends by saying that no city would be proof against surprise, +while the aerial ship could set fire to vessels at sea, and +destroy houses, fortresses, and cities by fire balls and bombs. +In fact, at the end of his treatise on the subject, he furnishes +a pretty complete resume of the activities of German Zeppelins. + +As already noted, Lana himself, owing to his vows of poverty, +was unable to do more than put his suggestions on paper, which +he did with a thoroughness that has procured him a place among +the really great pioneers of flying. + +It was nearly 200 years before any attempt was made to realise +his project; then, in 1843, M. Marey Monge set out to make the +globes and the ship as Lana detailed them. Monge's experiments +cost him the sum of 25,000 francs 75 centimes, which he expended +purely from love of scientific investigation. He chose to make +his globes of brass, about .004 in thickness, and weighing 1.465 +lbs. to the square yard. Having made his sphere of this metal, +he lined it with two thicknesses of tissue paper, varnished it +with oil, and set to work to empty it of air. This, however, he +never achieved, for such metal is incapable of sustaining the +pressure of the outside air, as Lana, had he had the means to +carry out experiments, would have ascertained. M. Monge's +sphere could never be emptied of air sufficiently to rise from +the earth; it ended in the melting-pot, ignominiously enough, +and all that Monge got from his experiment was the value of the +scrap metal and the satisfaction of knowing that Lana's theory +could never be translated into practice. + +Robert Hooke is less conspicuous than either Borelli or Lana; +his work, which came into the middle of the seventeenth century, +consisted of various experiments with regard to flight, from +which emerged 'a Module, which by the help of Springs and Wings, +raised and sustained itself in the air.' This must be reckoned +as the first model flying machine which actually flew, except +for da Vinci's helicopters; Hooke's model appears to have been +of the flapping-wing type--he attempted to copy the motion of +birds, but found from study and experiment that human muscles +were not sufficient to the task of lifting the human body. For +that reason, he says, 'I applied my mind to contrive a way to +make artificial muscles,' but in this he was, as he expresses +it, 'frustrated of my expectations.' Hooke's claim to fame +rests mainly on his successful model; the rest of his work is of +too scrappy a nature to rank as a serious contribution to the +study of flight. + +Contemporary with Hooke was one Allard, who, in France, +undertook to emulate the Saracen of Constantinople to a certain +extent. Allard was a tight-rope dancer who either did or was +said to have done short gliding flights--the matter is open to +question--and finally stated that he would, at St Germains, fly +from the terrace in the king's presence. He made the attempt, +but merely fell, as did the Saracen some centuries before, +causing himself serious injury. Allard cannot be regarded as a +contributor to the development of aeronautics in any way, and is +only mentioned as typical of the way in which, up to the time of +the Wright brothers, flying was regarded. Even unto this day +there are many who still believe that, with a pair of wings, man +ought to be able to fly, and that the mathematical data +necessary to effective construction simply do not exist. This +attitude was reasonable enough in an unlearned age, and Allard +was one--a little more conspicuous than the majority--among many +who made experiment in ignorance, with more or less danger to +themselves and without practical result of any kind. + +The seventeenth century was not to end, however, without +practical experiment of a noteworthy kind in gliding flight. +Among the recruits to the ranks of pioneers was a certain +Besnier, a locksmith of Sable, who somewhere between 1675 and +1680 constructed a glider of which a crude picture has come down +to modern times. The apparatus, as will be seen, consisted of +two rods with hinged flaps, and the original designer of the +picture seems to have had but a small space in which to draw, +since obviously the flaps must have been much larger than those +shown. Besnier placed the rods on his shoulders, and worked the +flaps by cords attached to his hands and feet--the flaps opened +as they fell, and closed as they rose, so the device as a whole +must be regarded as a sort of flapping glider. Having by +experiment proved his apparatus successful, Besnier promptly +sold it to a travelling showman of the period, and forthwith set +about constructing a second set, with which he made gliding +flights of considerable height and distance. Like Lilienthal, +Besnier projected himself into space from some height, and then, +according to the contemporary records, he was able to cross a +river of considerable size before coming to earth. It does not +appear that he had any imitators, or that any advantage whatever +was taken of his experiments; the age was one in which he would +be regarded rather as a freak exhibitor than as a serious +student, and possibly, considering his origin and the sale of +his first apparatus to such a client, he regarded the matter +himself as more in the nature of an amusement than as a +discovery. + +Borelli, coming at the end of the century, proved to his own +satisfaction and that of his fellows that flapping wing flight +was an impossibility; the capabilities of the plane were as yet +undreamed, and the prime mover that should make the plane +available for flight was deep in the womb of time. Da Vinci's +work was forgotten--flight was an impossibility, or at best such +a useless show as Besnier was able to give. + +The eighteenth century was almost barren of experiment. Emanuel +Swedenborg, having invented a new religion, set about inventing +a flying machine, and succeeded theoretically, publishing the +result of his investigations as follows:-- + +'Let a car or boat or some like object be made of light material +such as cork or bark, with a room within it for the operator. +Secondly, in front as well as behind, or all round, set a +widely-stretched sail parallel to the machine forming within a +hollow or bend which could be reefed like the sails of a ship. +Thirdly, place wings on the sides, to be worked up and down by a +spiral spring, these wings also to be hollow below in order to +increase the force and velocity, take in the air, and make the +resistance as great as may be required. These, too, should be +of light material and of sufficient size; they should be in the +shape of birds' wings, or the sails of a windmill, or some such +shape, and should be tilted obliquely upwards, and made so as to +collapse on the upward stroke and expand on the downward. +Fourth, place a balance or beam below, hanging down +perpendicularly for some distance with a small weight attached +to its end, pendent exactly in line with the centre of gravity; +the longer this beam is, the lighter must it be, for it must +have the same proportion as the well-known vectis or steel-yard. +This would serve to restore the balance of the machine if it +should lean over to any of the four sides. Fifthly, the wings +would perhaps have greater force, so as to increase the +resistance and make the flight easier, if a hood or shield were +placed over them, as is the case with certain insects. Sixthly, +when the sails are expanded so as to occupy a great surface and +much air, with a balance keeping them horizontal, only a small +force would be needed to move the machine back and forth in a +circle, and up and down. And, after it has gained momentum to +move slowly upwards, a slight movement and an even bearing would +keep it balanced in the air and would determine its direction at +will.' + +The only point in this worthy of any note is the first device +for maintaining stability automatically--Swedenborg certainly +scored a point there. For the rest. his theory was but theory, +incapable of being put to practice--he does not appear to have +made any attempt at advance beyond the mere suggestion. + +Some ten years before his time the state of knowledge with +regard to flying in Europe was demonstrated by an order granted +by the King of Portugal to Friar Lourenzo de Guzman, who claimed +to have invented a flying machine capable of actual flight. The +order stated that 'In order to encourage the suppliant to apply +himself with zeal toward the improvement of the new machine, +which is capable of producing the effects mentioned by him, I +grant unto him the first vacant place in my College of Barcelos +or Santarem, and the first professorship of mathematics in my +University of Coimbra, with the annual pension of 600,000 reis +during his life.--Lisbon, 17th of March, 1709.' + +What happened to Guzman when the non-existence of the machine +was discovered is one of the things that is well outside the +province of aeronautics. He was charlatan pure and simple, as +far as actual flight was concerned, though he had some ideas +respecting the design of hot-air balloons, according to +Tissandier. (La Navigation Aerienne.) His flying machine was to +contain, among other devices, bellows to produce artificial wind +when the real article failed, and also magnets in globes to draw +the vessel in an upward direction and maintain its buoyancy. +Some draughtsman, apparently gifted with as vivid imagination as +Guzman himself, has given to the world an illustration of the +hypothetical vessel; it bears some resemblance to Lana's aerial +ship, from which fact one draws obvious conclusions. + +A rather amusing claim to solving the problem of flight was +made in the middle of the eighteenth century by one Grimaldi, a +'famous and unique Engineer' who, as a matter of actual fact, +spent twenty years in missionary work in India, and employed the +spare time that missionary work left him in bringing his +invention to a workable state. The invention is described as a +'box which with the aid of clockwork rises in the air, and goes +with such lightness and strong rapidity that it succeeds in +flying a journey of seven leagues in an hour. It is made in the +fashion of a bird; the wings from end to end are 25 feet in +extent. The body is composed of cork, artistically joined +together and well fastened with metal wire, covered with +parchment and feathers. The wings are made of catgut and +whalebone, and covered also with the same parchment and +feathers, and each wing is folded in three seams. In the body +of the machine are contained thirty wheels of unique work, with +two brass globes and little chains which alternately wind up a +counterpoise; with the aid of six brass vases, full of a certain +quantity of quicksilver, which run in some pulleys, the machine +is kept by the artist in due equilibrium and balance. By means, +then, of the friction between a steel wheel adequately tempered +and a very heavy and surprising piece of lodestone, the whole is +kept in a regulated forward movement, given, however, a right +state of the winds, since the machine cannot fly so much in +totally calm weather as in stormy. This prodigious machine is +directed and guided by a tail seven palmi long, which is +attached to the knees and ankles of the inventor by leather +straps; by stretching out his legs, either to the right or to +the left, he moves the machine in whichever direction he +pleases.... The machine's flight lasts only three hours, after +which the wings gradually close themselves, when the inventor, +perceiving this, goes down gently, so as to get on his own feet, +and then winds up the clockwork and gets himself ready again +upon the wings for the continuation of a new flight. He himself +told us that if by chance one of the wheels came off or if one +of the wings broke, it is certain he would inevitably fall +rapidly to the ground, and, therefore, he does not rise more +than the height of a tree or two, as also he only once put +himself in the risk of crossing the sea, and that was from +Calais to Dover, and the same morning he arrived in London.' + +And yet there are still quite a number of people who persist in +stating that Bleriot was the first man to fly across the +Channel! + +A study of the development of the helicopter principle was +published in France in 1868, when the great French engineer +Paucton produced his Theorie de la Vis d'Archimede. For some +inexplicable reason, Paucton was not satisfied with the term +'helicopter,' but preferred to call it a 'pterophore,' a name +which, so far as can be ascertained, has not been adopted by any +other writer or investigator. Paucton stated that, since a man +is capable of sufficient force to overcome the weight of his own +body, it is only necessary to give him a machine which acts on +the air 'with all the force of which it is capable and at its +utmost speed,' and he will then be able to lift himself in the +air, just as by the exertion of all his strength he is able to +lift himself in water. 'It would seem,' says Paucton, 'that in +the pterophore, attached vertically to a carriage, the whole +built lightly and carefully assembled, he has found something +that will give him this result in all perfection. In +construction, one would be careful that the machine produced the +least friction possible, and naturally it ought to produce +little, as it would not be at all complicated. The new +Daedalus, sitting comfortably in his carriage, would by means of +a crank give to the pterophore a suitable circular (or +revolving) speed. This single pterophore would lift him +vertically, but in order to move horizontally he should be +supplied with a tail in the shape of another pterophore. When +he wished to stop for a little time, valves fixed firmly across +the end of the space between the blades would automatically +close the openings through which the air flows, and change the +pterophore into an unbroken surface which would resist the flow +of air and retard the fall of the machine to a considerable +degree.' + +The doctrine thus set forth might appear plausible, but it is +based on the common misconception that all the force which might +be put into the helicopter or 'pterophore' would be utilised for +lifting or propelling the vehicle through the air, just as a +propeller uses all its power to drive a ship through water. +But, in applying such a propelling force to the air, most of the +force is utilised in maintaining aerodynamic support--as a +matter of fact, more force is needed to maintain this support +than the muscle of man could possibly furnish to a lifting +screw, and even if the helicopter were applied to a full-sized, +engine-driven air vehicle, the rate of ascent would depend on +the amount of surplus power that could be carried. For example, +an upward lift of 1,000 pounds from a propeller 15 feet in +diameter would demand an expenditure of 50 horse-power under the +best possible conditions, and in order to lift this load +vertically through such atmospheric pressure as exists at +sea-level or thereabouts, an additional 20 horsepower would be +required to attain a rate of 11 feet per second--50 horse-power +must be continually provided for the mere support of the load, +and the additional 20 horse-power must be continually provided +in order to lift it. Although, in model form, there is nothing +quite so strikingly successful as the helicopter in the range of +flying machines, yet the essential weight increases so +disproportionately to the effective area that it is necessary to +go but very little beyond model dimensions for the helicopter to +become quite ineffective. + +That is not to say that the lifting screw must be totally ruled +out so far as the construction of aircraft is concerned. Much +is still empirical, so far as this branch of aeronautics is +concerned, and consideration of the structural features of a +propeller goes to show that the relations of essential weight +and effective area do not altogether apply in practice as they +stand in theory. Paucton's dream, in some modified form, may yet +become reality--it is only so short a time ago as 1896 that Lord +Kelvin stated he had not the smallest molecule of faith in +aerial navigation, and since the whole history of flight +consists in proving the impossible possible, the helicopter may +yet challenge the propelled plane surface for aerial supremacy. + +It does not appear that Paucton went beyond theory, nor is there +in his theory any advance toward practical flight--da Vinci +could have told him as much as he knew. He was followed by +Meerwein, who invented an apparatus apparently something between +a flapping wing machine and a glider, consisting of two wings, +which were to be operated by means of a rod; the venturesome one +who would fly by means of this apparatus had to lie in a +horizontal position beneath the wings to work the rod. Meerwein +deserves a place of mention, however, by reason of his +investigations into the amount of surface necessary to support a +given weight. Taking that weight at 200 pounds--which would +allow for the weight of a man and a very light apparatus--he +estimated that 126 square feet would be necessary for support. +His pamphlet, published at Basle in 1784, shows him to have been +a painstaking student of the potentialities of flight. + +Jean-Pierre Blanchard, later to acquire fame in connection with +balloon flight, conceived and described a curious vehicle, of +which he even announced trials as impending. His trials were +postponed time after time, and it appears that he became +convinced in the end of the futility of his device, being +assisted to such a conclusion by Lalande, the astronomer, who +repeated Borelli's statement that it was impossible for man ever +to fly by his own strength. This was in the closing days of the +French monarchy, and the ascent of the Montgolfiers' first +hot-air balloon in 1783--which shall be told more fully in its +place--put an end to all French experiments with heavier- +than-air apparatus, though in England the genius of Cayley was +about to bud, and even in France there were those who understood +that ballooning was not true flight. + + + +III. SIR GEORGE CAYLEY--THOMAS WALKER + +On the fifth of June, 1783, the Montgolfiers' hot-air balloon +rose at Versailles, and in its rising divided the study of the +conquest of the air into two definite parts, the one being +concerned with the propulsion of gas lifted, lighter-than-air +vehicles, and the other being crystallised in one sentence by +Sir George Cayley: 'The whole problem,' he stated, 'is +confined within these limits, viz.: to make a surface support a +given weight by the application of power to the resistance of +the air.' For about ten years the balloon held the field +entirely, being regarded as the only solution of the problem of +flight that man could ever compass. So definite for a time was +this view on the eastern side of the Channel that for some years +practically all the progress that was made in the development of +power-driven planes was made in Britain. + +In 1800 a certain Dr Thomas Young demonstrated that certain +curved surfaces suspended by a thread moved into and not away +from a horizontal current of air, but the demonstration, which +approaches perilously near to perpetual motion if the current be +truly horizontal, has never been successfully repeated, so that +there is more than a suspicion that Young's air-current was NOT +horizontal. Others had made and were making experiments on the +resistance offered to the air by flat surfaces, when Cayley came +to study and record, earning such a place among the pioneers as +to win the title of 'father of British aeronautics.' + +Cayley was a man in advance of his time, in many ways. Of +independent means, he made the grand tour which was considered +necessary to the education of every young man of position, and +during this excursion he was more engaged in studies of a +semi-scientific character than in the pursuits that normally +filled such a period. His various writings prove that +throughout his life aeronautics was the foremost subject in his +mind; the Mechanic's Magazine, Nicholson's Journal, the +Philosophical Magazine, and other periodicals of like nature +bear witness to Cayley's continued research into the subject of +flight. He approached the subject after the manner of the +trained scientist, analysing the mechanical properties of air +under chemical and physical action. Then he set to work to +ascertain the power necessary for aerial flight, and was one of +the first to enunciate the fallacy of the hopes of successful +flight by means of the steam engine of those days, owing to the +fact that it was impossible to obtain a given power with a given +weight. + +Yet his conclusions on this point were not altogether negative, +for as early as 1810 he stated that he could construct a balloon +which could travel with passengers at 20 miles an hour--he was +one of the first to consider the possibilities of applying power +to a balloon. Nearly thirty years later--in 1837--he made the +first attempt at establishing an aeronautical society, but at +that time the power-driven plane was regarded by the great +majority as an absurd dream of more or less mad inventors, while +ballooning ranked on about the same level as tight-rope walking, +being considered an adjunct to fairs and fetes, more a pastime +than a study. + +Up to the time of his death, in 1857, Cayley maintained his +study of aeronautical matters, and there is no doubt whatever +that his work went far in assisting the solution of the problem +of air conquest. His principal published work, a monograph +entitled Aerial Navigation, has been republished in the +admirable series of 'Aeronautical Classics' issued by the Royal +Aeronautical Society. He began this work by pointing out the +impossibility of flying by means of attached wings, an +impossibility due to the fact that, while the pectoral muscles +of a bird account for more than two-thirds of its whole muscular +strength, in a man the muscles available for flying, no matter +what mechanism might be used, would not exceed one-tenth of his +total strength. + +Cayley did not actually deny the possibility of a man flying by +muscular effort, however, but stated that 'the flight of a +strong man by great muscular exertion, though a curious and +interesting circumstance, inasmuch as it will probably be the +means of ascertaining finis power and supplying the basis +whereon to improve it, would be of little use.' + +From this he goes on to the possibility of using a Boulton and +Watt steam engine to develop the power necessary for flight, and +in this he saw a possibility of practical result. It is worthy +of note that in this connection he made mention of the +forerunner of the modern internal combustion engine; 'The +French,' he said, 'have lately shown the great power produced by +igniting inflammable powders in closed vessels, and several +years ago an engine was made to work in this country in a +similar manner by inflammation of spirit of tar.' In a +subsequent paragraph of his monograph he anticipates almost +exactly the construction of the Lenoir gas engine, which came +into being more than fifty-five years after his monograph was +published. + +Certain experiments detailed in his work were made to ascertain +the size of the surface necessary for the support of any given +weight. He accepted a truism of to-day in pointing out that in +any matters connected with aerial investigation, theory and +practice are as widely apart as the poles. Inclined at first to +favour the helicopter principle, he finally rejected this in +favour of the plane, with which he made numerous experiments. +During these, he ascertained the peculiar advantages of curved +surfaces, and saw the necessity of providing both vertical and +horizontal rudders in order to admit of side steering as well as +the control of ascent and descent, and for preserving +equilibrium. He may be said to have anticipated the work of +Lilienthal and Pilcher, since he constructed and experimented +with a fixed surface glider. 'It was beautiful,' he wrote +concerning this, 'to see this noble white bird sailing +majestically from the top of a hill to any given point of the +plain below it with perfect steadiness and safety, according to +the set of its rudder, merely by its own weight, descending at +an angle of about eight degrees with the horizon.' + +It is said that he once persuaded his gardener to trust himself +in this glider for a flight, but if Cayley himself ventured a +flight in it he has left no record of the fact. The following +extract from his work, Aerial Navigation, affords an instance of +the thoroughness of his investigations, and the concluding +paragraph also shows his faith in the ultimate triumph of +mankind in the matter of aerial flight:-- + +'The act of flying requires less exertion than from the +appearance is supposed. Not having sufficient data to ascertain +the exact degree of propelling power exerted by birds in the act +of flying, it is uncertain what degree of energy may be required +in this respect for vessels of aerial navigation; yet when we +consider the many hundreds of miles of continued flight exerted +by birds of passage, the idea of its being only a small effort +is greatly corroborated. To apply the power of the first mover +to the greatest advantage in producing this effect is a very +material point. The mode universally adopted by Nature is the +oblique waft of the wing. We have only to choose between the +direct beat overtaking the velocity of the current, like the oar +of a boat, or one applied like the wing, in some assigned degree +of obliquity to it. Suppose 35 feet per second to be the +velocity of an aerial vehicle, the oar must be moved with this +speed previous to its being able to receive any resistance; then +if it be only required to obtain a pressure of one-tenth of a +lb. upon each square foot it must exceed the velocity of the +current 7.3 feet per second. Hence its whole velocity must be +42.5 feet per second. Should the same surface be wafted +downward like a wing with the hinder edge inclined upward in an +angle of about 50 deg. 40 feet to the current it will overtake +it at a velocity of 3.5 feet per second; and as a slight unknown +angle of resistance generates a lb. pressure per square foot at +this velocity, probably a waft of a little more than 4 feet per +second would produce this effect, one-tenth part of which would +be the propelling power. The advantage of this mode of +application compared with the former is rather more than ten to +one. + +'In continuing the general principles of aerial navigation, for +the practice of the art, many mechanical difficulties present +themselves which require a considerable course of skilfully +applied experiments before they can be overcome; but, to a +certain extent, the air has already been made navigable, and no +one who has seen the steadiness with which weights to the amount +of ten stone (including four stone, the weight of the machine) +hover in the air can doubt of the ultimate accomplishment of +this object.' + +This extract from his work gives but a faint idea of the amount +of research for which Cayley was responsible. He had the +humility of the true investigator in scientific problems, and so +far as can be seen was never guilty of the great fault of so +many investigators in this subject--that of making claims which +he could not support. He was content to do, and pass after +having recorded his part, and although nearly half a century had +to pass between the time of his death and the first actual +flight by means of power-driven planes, yet he may be said to +have contributed very largely to the solution of the problem, +and his name will always rank high in the roll of the pioneers +of flight. + +Practically contemporary with Cayley was Thomas Walker, +concerning whom little is known save that he was a portrait +painter of Hull, where was published his pamphlet on The Art of +Flying in 1810, a second and amplified edition being produced, +also in Hull, in 1831. The pamphlet, which has been reproduced +in extenso in the Aeronautical Classics series published by the +Royal Aeronautical Society, displays a curious mixture of the +true scientific spirit and colossal conceit. Walker appears to +have been a man inclined to jump to conclusions, which carried +him up to the edge of discovery and left him vacillating there. + +The study of the two editions of his pamphlet side by side shows +that their author made considerable advances in the +practicability of his designs in the 21 intervening years, +though the drawings which accompany the text in both editions +fail to show anything really capable of flight. The great point +about Walker's work as a whole is its suggestiveness; he did not +hesitate to state that the 'art' of flying is as truly +mechanical as that of rowing a boat, and he had some conception +of the necessary mechanism, together with an absolute conviction +that he knew all there was to be known. 'Encouraged by the +public,' he says, 'I would not abandon my purpose of making +still further exertions to advance and complete an art, the +discovery of the TRUE PRINCIPLES (the italics are Walker's own) +of which, I trust, I can with certainty affirm to be my own.' + +The pamphlet begins with Walker's admiration of the mechanism of +flight as displayed by birds. 'It is now almost twenty years,' +he says, 'since I was first led to think, by the study of birds +and their means of flying, that if an artificial machine were +formed with wings in exact imitation of the mechanism of one of +those beautiful living machines, and applied in the very same +way upon the air, there could be no doubt of its being made to +fly, for it is an axiom in philosophy that the same cause will +ever produce the same effect.' With this he confesses his +inability to produce the said effect through lack of funds, +though he clothes this delicately in the phrase 'professional +avocations and other circumstances.' Owing to this inability he +published his designs that others might take advantage of them, +prefacing his own researches with a list of the very early +pioneers, and giving special mention to Friar Bacon, Bishop +Wilkins, and the Portuguese friar, De Guzman. But, although he +seems to suggest that others should avail themselves of his +theoretical knowledge, there is a curious incompleteness about +the designs accompanying his work, and about the work itself, +which seems to suggest that he had more knowledge to impart than +he chose to make public--or else that he came very near to +complete solution of the problem of flight, and stayed on the +threshold without knowing it. + +After a dissertation upon the history and strength of the +condor, and on the differences between the weights of birds, he +says: 'The following observations upon the wonderful difference +in the weight of some birds, with their apparent means of +supporting it in their flight, may tend to remove some +prejudices against my plan from the minds of some of my readers. +The weight of the humming-bird is one drachm, that of the condor +not less than four stone. Now, if we reduce four stone into +drachms we shall find the condor is 14,336 times as heavy as the +humming-bird. What an amazing disproportion of weight! Yet by +the same mechanical use of its wings the condor can overcome the +specific gravity of its body with as much ease as the little +humming-bird. But this is not all. We are informed that this +enormous bird possesses a power in its wings, so far exceeding +what is necessary for its own conveyance through the air, that +it can take up and fly away with a whole sheer in its talons, +with as much ease as an eagle would carry off, in the same +manner, a hare or a rabbit. This we may readily give credit to, +from the known fact of our little kestrel and the sparrow-hawk +frequently flying off with a partridge, which is nearly three +times the weight of these rapacious little birds.' + +After a few more observations he arrives at the following +conclusion: 'By attending to the progressive increase in the +weight of birds, from the delicate little humming-bird up to the +huge condor, we clearly discover that the addition of a few +ounces, pounds, or stones, is no obstacle to the art of flying; +the specific weight of birds avails nothing, for by their +possessing wings large enough, and sufficient power to work +them, they can accomplish the means of flying equally well upon +all the various scales and dimensions which we see in nature. +Such being a fact, in the name of reason and philosophy why +shall not man, with a pair of artificial wings, large enough, +and with sufficient power to strike them upon the air, be able +to produce the same effect?' + +Walker asserted definitely and with good ground that muscular +effort applied without mechanism is insufficient for human +flight, but he states that if an aeronautical boat were +constructed so that a man could sit in it in the same manner as +when rowing, such a man would be able to bring into play his +whole bodily strength for the purpose of flight, and at the same +time would be able to get an additional advantage by exerting +his strength upon a lever. At first he concluded there must be +expansion of wings large enough to resist in a sufficient degree +the specific gravity of whatever is attached to them, but in the +second edition of his work he altered this to 'expansion of flat +passive surfaces large enough to reduce the force of gravity so +as to float the machine upon the air with the man in it.' The +second requisite is strength enough to strike the wings with +sufficient force to complete the buoyancy and give a projectile +motion to the machine. Given these two requisites, Walker states +definitely that flying must be accomplished simply by muscular +exertion. 'If we are secure of these two requisites, and I am +very confident we are, we may calculate upon the success of +flight with as much certainty as upon our walking.' + +Walker appears to have gained some confidence from the +experiments of a certain M. Degen, a watchmaker of Vienna, who, +according to the Monthly Magazine of September, 1809, invented a +machine by means of which a person might raise himself into the +air. The said machine, according to the magazine, was formed of +two parachutes which might be folded up or extended at pleasure, +while the person who worked them was placed in the centre. This +account, however, was rather misleading, for the magazine +carefully avoided mention of a balloon to which the inventor +fixed his wings or parachutes. Walker, knowing nothing of the +balloon, concluded that Degen actually raised himself in the air, +though he is doubtful of the assertion that Degen managed to fly +in various directions, especially against the wind. + +Walker, after considering Degen and all his works, proceeds to +detail his own directions for the construction of a flying +machine, these being as follows: 'Make a car of as light +material as possible, but with sufficient strength to support a +man in it; provide a pair of wings about four feet each in +length; let them be horizontally expanded and fastened upon the +top edge of each side of the car, with two joints each, so as to +admit of a vertical motion to the wings, which motion may be +effected by a man sitting and working an upright lever in the +middle of the car. Extend in the front of the car a flat surface +of silk, which must be stretched out and kept fixed in a passive +state; there must be the same fixed behind the car; these two +surfaces must be perfectly equal in length and breadth and large +enough to cover a sufficient quantity of air to support the whole +weight as nearly in equilibrium as possible, thus we shall have a +great sustaining power in those passive surfaces and the active +wings will propel the car forward.' + +A description of how to launch this car is subsequently given: +'It becomes necessary,' says the theorist, 'that I should give +directions how it may be launched upon the air, which may be done +by various means; perhaps the following method may be found to +answer as well as any: Fix a poll upright in the earth, about +twenty feet in height, with two open collars to admit another +poll to slide upwards through them; let there be a sliding +platform made fast upon the top of the sliding poll; place the +car with a man in it upon the platform, then raise the platform +to the height of about thirty feet by means of the sliding poll, +let the sliding poll and platform suddenly fall down, the car +will then be left upon the air, and by its pressing the air a +projectile force will instantly propel the car forward; the man +in the car must then strike the active wings briskly upon the +air, which will so increase the projectile force as to become +superior to the force of gravitation, and if he inclines his +weight a little backward, the projectile impulse will drive the +car forward in an ascending direction. When the car is brought to +a sufficient altitude to clear the tops of hills, trees, +buildings, etc., the man, by sitting a little forward on his +seat, will then bring the wings upon a horizontal plane, and by +continuing the action of the wings he will be impelled forward +in that direction. To descend, he must desist from striking the +wings, and hold them on a level with their joints; the car will +then gradually come down, and when it is within five or six feet +of the ground the man must instantly strike the wings downwards, +and sit as far back as he can; he will by this means check the +projectile force, and cause the car to alight very gently with a +retrograde motion. The car, when up in the air, may be made to +turn to the right or to the left by forcing out one of the fins, +having one about eighteen inches long placed vertically on each +side of the car for that purpose, or perhaps merely by the man +inclining the weight of his body to one side.' + +Having stated how the thing is to be done, Walker is careful to +explain that when it is done there will be in it some practical +use, notably in respect of the conveyance of mails and +newspapers, or the saving of life at sea, or for exploration, +etc. It might even reduce the number of horses kept by man for +his use, by means of which a large amount of land might be set +free for the growth of food for human consumption. + +At the end of his work Walker admits the idea of steam power for +driving a flying machine in place of simple human exertion, but +he, like Cayley, saw a drawback to this in the weight of the +necessary engine. On the whole, he concluded, navigation of the +air by means of engine power would be mostly confined to the +construction of navigable balloons. + +As already noted, Walker's work is not over practical, and the +foregoing extract includes the most practical part of it; the +rest is a series of dissertations on bird flight, in which, +evidently, the portrait painter's observations were far less +thorough than those of da Vinci or Borelli. Taken on the whole, +Walker was a man with a hobby; he devoted to it much time and +thought, but it remained a hobby, nevertheless. His +observations have proved useful enough to give him a place among +the early students of flight, but a great drawback to his work +is the lack of practical experiment, by means of which alone +real advance could be made; for, as Cayley admitted, theory and +practice are very widely separated in the study of aviation, and +the whole history of flight is a matter of unexpected results +arising from scarcely foreseen causes, together with experiment +as patient as daring. + + + +IV. THE MIDDLE NINETEENTH CENTURY + +Both Cayley and Walker were theorists, though Cayley supported +his theoretical work with enough of practice to show that he +studied along right lines; a little after his time there came +practical men who brought to being the first machine which +actually flew by the application of power. Before their time, +however, mention must be made of the work of George Pocock of +Bristol, who, somewhere about 1840 invented what was described +as a 'kite carriage,' a vehicle which carried a number of +persons, and obtained its motive power from a large kite. It is +on record that, in the year 1846 one of these carriages conveyed +sixteen people from Bristol to London. Another device of +Pocock's was what he called a 'buoyant sail,' which was in +effect a man-lifting kite, and by means of which a passenger was +actually raised 100 yards from the ground, while the inventor's +son scaled a cliff 200 feet in height by means of one of these, +'buoyant sails.' This constitutes the first definitely recorded +experiment in the use of man-lifting kites. A History of the +Charvolant or Kite-carriage, published in London in 1851, states +that 'an experiment of a bold and very novel character was made +upon an extensive down, where a large wagon with a considerable +load was drawn along, whilst this huge machine at the same time +carried an observer aloft in the air, realising almost the +romance of flying.' + +Experimenting, two years after the appearance of the +'kite-carriage,' on the helicopter principle, W. H. Phillips +constructed a model machine which weighed two pounds; this was +fitted with revolving fans, driven by the combustion of +charcoal, nitre, and gypsum, producing steam which, discharging +into the air, caused the fans to revolve. The inventor stated +that 'all being arranged, the steam was up in a few seconds, +when the whole apparatus spun around like any top, and mounted +into the air faster than a bird; to what height it ascended I +had no means of ascertaining; the distance travelled was across +two fields, where, after a long search, I found the machine +minus the wings, which had been torn off in contact with the +ground.' This could hardly be described as successful flight, +but it was an advance in the construction of machines on the +helicopter principle, and it was the first steam-driven model of +the type which actually flew. The invention, however, was not +followed up. + +After Phillips, we come to the great figures of the middle +nineteenth century, W. S. Henson and John Stringfellow. Cayley +had shown, in 1809, how success might be attained by developing +the idea of the plane surface so driven as to take advantage of +the resistance offered by the air, and Henson, who as early as +1840 was experimenting with model gliders and light steam +engines, evolved and patented an idea for something very nearly +resembling the monoplane of the early twentieth century. His +patent, No. 9478, of the year 1842 explains the principle of the +machine as follows:-- + +In order that the description hereafter given be rendered clear, +I will first shortly explain the principle on which the machine +is constructed. If any light and flat or nearly flat article be +projected or thrown edgewise in a slightly inclined position, +the same will rise on the air till the force exerted is +expended, when the article so thrown or projected will descend; +and it will readily be conceived that, if the article so +projected or thrown possessed in itself a continuous power or +force equal to that used in throwing or projecting it, the +article would continue to ascend so long as the forward part of +the surface was upwards in respect to the hinder part, and that +such article, when the power was stopped, or when the +inclination was reversed, would descend by gravity aided by the +force of the power contained in the article, if the power be +continued, thus imitating the flight of a bird. + +Now, the first part of my invention consists of an apparatus so +constructed as to offer a very extended surface or plane of a +light yet strong construction, which will have the same relation +to the general machine which the extended wings of a bird have +to the body when a bird is skimming in the air; but in place of +the movement or power for onward progress being obtained by +movement of the extended surface or plane, as is the case with +the wings of birds, I apply suitable paddle-wheels or other +proper mechanical propellers worked by a steam or other +sufficiently light engine, and thus obtain the requisite power +for onward movement to the plane or extended surface; and in +order to give control as to the upward and downward direction of +such a machine I apply a tail to the extended surface which is +capable of being inclined or raised, so that when the power is +acting to propel the machine, by inclining the tail upwards, +the resistance offered by the air will cause the machine to rise +on the air; and, on the contrary, when the inclination of the +tail is reversed, the machine will immediately be propelled +downwards, and pass through a plane more or less inclined to the +horizon as the inclination of the tail is greater or less; and +in order to guide the machine as to the lateral direction which +it shall take, I apply a vertical rudder or second tail, and, +according as the same is inclined in one direction or the other, +so will be the direction of the machine.' + +The machine in question was very large, and differed very little +from the modern monoplane; the materials were to be spars of +bamboo and hollow wood, with diagonal wire bracing. The surface +of the planes was to amount to 4,500 square feet, and the tail, +triangular in form (here modern practice diverges) was to be +1,500 square feet. The inventor estimated that there would be a +sustaining power of half a pound per square foot, and the +driving power was to be supplied by a steam engine of 25 to 30 +horse-power, driving two six-bladed propellers. Henson was +largely dependent on Stringfellow for many details of his +design, more especially with regard to the construction of the +engine. + +The publication of the patent attracted a great amount of public +attention, and the illustrations in contemporary journals, +representing the machine flying over the pyramids and the +Channel, anticipated fact by sixty years and more; the +scientific world was divided, as it was up to the actual +accomplishment of flight, as to the value of the invention. + +Strongfellow and Henson became associated after the conception +of their design, with an attorney named Colombine, and a Mr +Marriott, and between the four of them a project grew for +putting the whole thing on a commercial basis--Henson and +Stringfellow were to supply the idea; Marriott, knowing a member +of Parliament, would be useful in getting a company +incorporated, and Colombine would look after the purely legal +side of the business. Thus an application was made by Mr +Roebuck, Marriott's M.P., for an act of incorporation for 'The +Aerial Steam Transit Company,' Roebuck moving to bring in the +bill on the 24th of March, 1843. The prospectus, calling for +funds for the development of the invention, makes interesting +reading at this stage of aeronautical development; it was as +follows: + + PROPOSAL. + +For subscriptions of sums of L100, in furtherance of an +Extraordinary Invention not at present safe to be developed by +securing the necessary Patents, for which three times the sum +advanced, namely, L300, is conditionally guaranteed for each +subscription on February 1, 1844, in case of the anticipations +being realised, with the option of the subscribers being +shareholders for the large amount if so desired, but not +otherwise. + --------- +An Invention has recently been discovered, which if ultimately +successful will be without parallel even in the age which +introduced to the world the wonderful effects of gas and of +steam. + +The discovery is of that peculiar nature, so simple in principle +yet so perfect in all the ingredients required for complete and +permanent success, that to promulgate it at present would wholly +defeat its development by the immense competition which would +ensue, and the views of the originator be entirely frustrated. + +This work, the result of years of labour and study, presents a +wonderful instance of the adaptation of laws long since proved +to the scientific world combined with established principles so +judiciously and carefully arranged, as to produce a discovery +perfect in all its parts and alike in harmony with the laws of +Nature and of science. + +The Invention has been subjected to several tests and +examinations and the results are most satisfactory so much so +that nothing but the completion of the undertaking is required +to determine its practical operation, which being once +established its utility is undoubted, as it would be a necessary +possession of every empire, and it were hardly too much to say, +of every individual of competent means in the civilised world. + +Its qualities and capabilities are so vast that it were +impossible and, even if possible, unsafe to develop them +further, but some idea may be formed from the fact that as a +preliminary measure patents in Great Britain Ireland, Scotland, +the Colonies, France, Belgium, and the United States, and every +other country where protection to the first discoveries of an +Invention is granted, will of necessity be immediately obtained, +and by the time these are perfected, which it is estimated will +be in the month of February, the Invention will be fit for +Public Trial, but until the Patents are sealed any further +disclosure would be most dangerous to the principle on which it +is based. + +Under these circumstances, it is proposed to raise an +immediate sum of L2,000 in furtherance of the Projector's views, +and as some protection to the parties who may embark in the +matter, that this is not a visionary plan for objects +imperfectly considered, Mr Colombine, to whom the secret has +been confided, has allowed his name to be used on the occasion, +and who will if referred to corroborate this statement, and +convince any inquirer of the reasonable prospects of large +pecuniary results following the development of the Invention. + +It is, therefore, intended to raise the sum of L2,000 in twenty +sums of L100 each (of which any subscriber may take one or more +not exceeding five in number to be held by any individual) the +amount of which is to be paid into the hands of Mr Colombine as +General Manager of the concern to be by him appropriated in +procuring the several Patents and providing the expenses +incidental to the works in progress. For each of which sums of +L100 it is intended and agreed that twelve months after the 1st +February next, the several parties subscribing shall receive as +an equivalent for the risk to be run the sum of L300 for each of +the sums of L100 now subscribed, provided when the time arrives +the Patents shall be found to answer the purposes intended. + +As full and complete success is alone looked to, no moderate or +imperfect benefit is to be anticipated, but the work, if it once +passes the necessary ordeal, to which inventions of every kind +must be first subject, will then be regarded by every one as the +most astonishing discovery of modern times; no half success can +follow, and therefore the full nature of the risk is immediately +ascertained. + +The intention is to work and prove the Patent by collective +instead of individual aid as less hazardous at first end more +advantageous in the result for the Inventor, as well as others, +by having the interest of several engaged in aiding one common +object--the development of a Great Plan. The failure is not +feared, yet as perfect success might, by possibility, not ensue, +it is necessary to provide for that result, and the parties +concerned make it a condition that no return of the subscribed +money shall be required, if the Patents shall by any unforeseen +circumstances not be capable of being worked at all; against +which, the first application of the money subscribed, that of +securing the Patents, affords a reasonable security, as no one +without solid grounds would think of such an expenditure. + +It is perfectly needless to state that no risk or responsibility +of any kind can arise beyond the payment of the sum to be +subscribed under any circumstances whatever. + +As soon as the Patents shall be perfected and proved it is +contemplated, so far as may be found practicable, to further the +great object in view a Company shall be formed but respecting +which it is unnecessary to state further details, than that a +preference will be given to all those persons who now subscribe, +and to whom shares shall be appropriated according to the larger +amount (being three times the sum to be paid by each person) +contemplated to be returned as soon as the success of the +Invention shall have been established, at their option, or the +money paid, whereby the Subscriber will have the means of either +withdrawing with a large pecuniary benefit, or by continuing his +interest in the concern lay the foundation for participating in +the immense benefit which must follow the success of the plan. + +It is not pretended to conceal that the project is a +speculation--all parties believe that perfect success, and +thence incalculable advantage of every kind, will follow to +every individual joining in this great undertaking; but the +Gentlemen engaged in it wish that no concealment of the +consequences, perfect success, or possible failure, should in +the slightest degree be inferred. They believe this will prove +the germ of a mighty work, and in that belief call for the +operation of others with no visionary object, but a legitimate +one before them, to attain that point where perfect success will +be secured from their combined exertions. + +All applications to be made to D. E. Colombine, Esquire, 8 +Carlton Chambers, Regent Street. + +The applications did not materialise, as was only to be expected +in view of the vagueness of the proposals. Colombine did some +advertising, and Mr Roebuck expressed himself as unwilling to +proceed further in the venture. Henson experimented with models +to a certain extent, while Stringfellow looked for funds for the +construction of a full-sized monoplane. In November of 1843 he +suggested that he and Henson should construct a large model out +of their own funds. On Henson's suggestion Colombine and +Marriott were bought out as regards the original patent, and +Stringfellow and Henson entered into an agreement and set to +work. + +Their work is briefly described in a little pamphlet by F. J. +Stringfellow, entitled A few Remarks on what has been done with +screw-propelled Aero-plane Machines from 1809 to 1892. The +author writes with regard to the work that his father and Henson +undertook:-- + +'They commenced the construction of a small model operated by a +spring, and laid down the larger model 20 ft. from tip to tip +of planes, 3 1/2 ft. wide, giving 70 ft. of sustaining surface, +about 10 more in the tail. The making of this model required +great consideration; various supports for the wings were tried, +so as to combine lightness with firmness, strength and rigidity. + +'The planes were staid from three sets of fish-shaped masts, and +rigged square and firm by flat steel rigging. The engine and +boiler were put in the car to drive two screw-propellers, right +and left-handed, 3 ft. in diameter, with four blades each, +occupying three-quarters of the area of the circumference, set +at an angle of 60 degrees. A considerable time was spent in +perfecting the motive power. Compressed air was tried and +abandoned. Tappets, cams, and eccentrics were all tried, to work +the slide valve, to obtain the best results. The piston rod of +engine passed through both ends of the cylinder, and with long +connecting rods worked direct on the crank of the propellers. +From memorandum of experiments still preserved the following is +a copy of one: June, 27th, 1845, water 50 ozs., spirit 10 ozs., +lamp lit 8.45, gauge moves 8.46, engine started 8.48 (100 lb. +pressure), engine stopped 8.57, worked 9 minutes, 2,288 +revolutions, average 254 per minute. No priming, 40 ozs. water +consumed, propulsion (thrust of propellers), 5 lbs. 4 1/2 ozs. +at commencement, steady, 4 lbs. 1/2 oz., 57 revolutions to 1 oz. +water, steam cut off one-third from beginning. + +'The diameter of cylinder of engine was 1 1/2 inch, length of +stroke 3 inches. + +'In the meantime an engine was also made for the smaller model, +and a wing action tried, but with poor results. The time was +mostly devoted to the larger model, and in 1847 a tent was +erected on Bala Down, about two miles from Chard, and the model +taken up one night by the workmen. The experiments were not so +favourable as was expected. The machine could not support +itself for any distance, but, when launched off, gradually +descended, although the power and surface should have been +ample; indeed, according to latest calculations, the thrust +should have carried more than three times the weight, for there +was a thrust of 5 lbs. from the propellers, and a surface of +over 70 square feet to sustain under 30 lbs., but necessary +speed was lacking.' + +Stringfellow himself explained the failure as follows:-- + +'There stood our aerial protegee in all her purity--too +delicate, too fragile, too beautiful for this rough world; at +least those were my ideas at the time, but little did I think +how soon it was to be realised. I soon found, before I had time +to introduce the spark, a drooping in the wings, a flagging in +all the parts. In less than ten minutes the machine was +saturated with wet from a deposit of dew, so that anything like +a trial was impossible by night. I did not consider we could get +the silk tight and rigid enough. Indeed, the framework +altogether was too weak. The steam-engine was the best part. +Our want of success was not for want of power or sustaining +surface, but for want of proper adaptation of the means to the +end of the various parts.' + +Henson, who had spent a considerable amount of money in these +experimental constructions, consoled himself for failure by +venturing into matrimony; in 1849 he went to America, leaving +Stringfellow to continue experimenting alone. From 1846 to 1848 +Stringfellow worked on what is really an epoch-making item in +the history of aeronautics--the first engine-driven aeroplane +which actually flew. The machine in question had a 10 foot +span, and was 2 ft. across in the widest part of the wing; the +length of tail was 3 ft. 6 ins., and the span of tail in the +widest part 22 ins., the total sustaining area being about 14 +sq. ft. The motive power consisted of an engine with a cylinder +of three-quarter inch diameter and a two-inch stroke; between +this and the crank shaft was a bevelled gear giving three +revolutions of the propellers to every stroke of the engine; the +propellers, right and left screw, were four-bladed and 16 inches +in diameter. The total weight of the model with engine was 8 +lbs. Its successful flight is ascribed to the fact that +Stringfellow curved the wings, giving them rigid front edges and +flexible trailing edges, as suggested long before both by Da +Vinci and Borelli, but never before put into practice. + +Mr F. J. Stringfellow, in the pamphlet quoted above, gives the +best account of the flight of this model: 'My father had +constructed another small model which was finished early in +1848, and having the loan of a long room in a disused lace +factory, early in June the small model was moved there for +experiments. The room was about 22 yards long and from 10 to 12 +ft. high.... The inclined wire for starting the machine occupied +less than half the length of the room and left space at the end +for the machine to clear the floor. In the first experiment the +tail was set at too high an angle, and the machine rose too +rapidly on leaving the wire. After going a few yards it slid +back as if coming down an inclined plane, at such an angle that +the point of the tail struck the ground and was broken. The +tail was repaired and set at a smaller angle. The steam was +again got up, and the machine started down the wire, and, upon +reaching the point of self-detachment, it gradually rose until +it reached the farther end of the room, striking a hole in the +canvas placed to stop it. In experiments the machine flew well, +when rising as much as one in seven. The late Rev. J. Riste, +Esq., lace manufacturer, Northcote Spicer, Esq., J. Toms, Esq., +and others witnessed experiments. Mr Marriatt, late of the San +Francisco News Letter brought down from London Mr Ellis, the +then lessee of Cremorne Gardens, Mr Partridge, and Lieutenant +Gale, the aeronaut, to witness experiments. Mr Ellis offered to +construct a covered way at Cremorne for experiments. Mr +Stringfellow repaired to Cremorne, but not much better +accommodations than he had at home were provided, owing to +unfulfilled engagement as to room. Mr Stringfellow was +preparing for departure when a party of gentlemen unconnected +with the Gardens begged to see an experiment, and finding them +able to appreciate his endeavours, he got up steam and started +the model down the wire. When it arrived at the spot where it +should leave the wire it appeared to meet with some obstruction, +and threatened to come to the ground, but it soon recovered +itself and darted off in as fair a flight as it was possible to +make at a distance of about 40 yards, where it was stopped by +the canvas. + +'Having now demonstrated the practicability of making a +steam-engine fly, and finding nothing but a pecuniary loss and +little honour, this experimenter rested for a long time, +satisfied with what he had effected. The subject, however, had +to him special charms, and he still contemplated the renewal of +his experiments.' + +It appears that Stringfellow's interest did not revive +sufficiently for the continuance of the experiments until the +founding of the Aeronautical Society of Great Britain in 1866. +Wenham's paper on Aerial Locomotion read at the first meeting of +the Society, which was held at the Society of Arts under the +Presidency of the Duke of Argyll, was the means of bringing +Stringfellow back into the field. It was Wenham's suggestion, +in the first place, that monoplane design should be abandoned +for the superposition of planes; acting on this suggestion +Stringfellow constructed a model triplane, and also designed a +steam engine of slightly over one horse-power, and a one +horse-power copper boiler and fire box which, although capable +of sustaining a pressure of 500 lbs. to the square inch, weighed +only about 40 lbs. + +Both the engine and the triplane model were exhibited at the +first Aeronautical Exhibition held at the Crystal Palace in +1868. The triplane had a supporting surface of 28 sq. ft.; +inclusive of engine, boiler, fuel, and water its total weight +was under 12 lbs. The engine worked two 21 in. propellers at +600 revolutions per minute, and developed 100 lbs. steam +pressure in five minutes, yielding one-third horse-power. Since +no free flight was allowed in the Exhibition, owing to danger +from fire, the triplane was suspended from a wire in the nave of +the building, and it was noted that, when running along the +wire, the model made a perceptible lift. + +A prize of L100 was awarded to the steam engine as the lightest +steam engine in proportion to its power. The engine and model +together may be reckoned as Stringfellow's best achievement. He +used his L100 in preparation for further experiments, but he +was now an old man, and his work was practically done. Both the +triplane and the engine were eventually bought for the +Washington Museum; Stringfellow's earlier models, together with +those constructed by him in conjunction with Henson, remain in +this country in the Victoria and Albert Museum. + +John Stringfellow died on December 13th, 1883. His place in the +history of aeronautics is at least equal to that of Cayley, and +it may be said that he laid the foundation of such work as was +subsequently accomplished by Maxim, Langley, and their fellows. +It was the coming of the internal combustion engine that +rendered flight practicable, and had this prime mover been +available in John Stringfellow's day the Wright brothers' +achievement might have been antedated by half a century. + + + +V. WENHAM, LE BRIS, AND SOME OTHERS + +There are few outstanding events in the development of +aeronautics between Stringfellow's final achievement and the +work of such men as Lilienthal, Pilcher, Montgomery, and their +kind; in spite of this, the later middle decades of the +nineteenth century witnessed a considerable amount of spade work +both in England and in France, the two countries which led in +the way in aeronautical development until Lilienthal gave honour +to Germany, and Langley and Montgomery paved the way for the +Wright Brothers in America. + +Two abortive attempts characterised the sixties of last century +in France. As regards the first of these, it was carried out by +three men, Nadar, Ponton d'Amecourt, and De la Landelle, who +conceived the idea of a full-sized helicopter machine. +D'Amecourt exhibited a steam model, constructed in 1865, at the +Aeronautical Society's Exhibition in 1868. The engine was +aluminium with cylinders of bronze, driving two screws placed +one above the other and rotating in Opposite directions, but the +power was not sufficient to lift the model. De la Landelle's +principal achievement consisted in the publication in 1863 of a +book entitled Aviation which has a certain historical value; he +got out several designs for large machines on the helicopter +principle, but did little more until the three combined in the +attempt to raise funds for the construction of their +full-sized machine. Since the funds were not forthcoming, +Nadar took to ballooning as the means of raising money; +apparently he found this substitute for real flight sufficiently +interesting to divert him from the study of the helicopter +principle, for the experiment went no further. + +The other experimenter of this period, one Count d'Esterno, took +out a patent in 1864 for a soaring machine which allowed for +alteration of the angle of incidence of the wings in the manner +that was subsequently carried out by the Wright Brothers. It +was not until 1883 that any attempt was made to put this patent +to practical use, and, as the inventor died while it was under +construction, it was never completed. D'Esterno was also +responsible for the production of a work entitled Du Vol des +Oiseaux, which is a very remarkable study of the flight of +birds. + +Mention has already been made of the founding of the +Aeronautical Society of Great Britain, which, since 1918 has +been the Royal Aeronautical Society. 1866 witnessed the first +meeting of the Society under the Presidency of the Duke of +Argyll, when in June, at the Society of Arts, Francis Herbert +Wenham read his now classic paper Aerial Locomotion. Certain +quotations from this will show how clearly Wenham had thought +out the problems connected with flight. + +'The first subject for consideration is the proportion of +surface to weight, and their combined effect in descending +perpendicularly through the atmosphere. The datum is here based +upon the consideration of safety, for it may sometimes be +needful for a living being to drop passively, without muscular +effort. One square foot of sustaining surface for every pound +of the total weight will be sufficient for security. + +'According to Smeaton's table of atmospheric resistances, to +produce a force of one pound on a square foot, the wind must +move against the plane (or which is the same thing, the plane +against the wind), at the rate of twenty-two feet per second, or +1,320 feet per minute, equal to fifteen miles per hour. The +resistance of the air will now balance the weight on the +descending surface, and, consequently, it cannot exceed that +speed. Now, twenty-two feet per second is the velocity acquired +at the end of a fall of eight feet--a height from which a +well-knit man or animal may leap down without much risk of +injury. Therefore, if a man with parachute weigh together 143 +lbs., spreading the same number of square feet of surface +contained in a circle fourteen and a half feet in diameter, he +will descend at perhaps an unpleasant velocity, but with safety +to life and limb. + +'It is a remarkable fact how this proportion of wing-surface to +weight extends throughout a great variety of the flying portion +of the animal kingdom, even down to hornets, bees, and other +insects. In some instances, however, as in the gallinaceous +tribe, including pheasants, this area is somewhat exceeded, but +they are known to be very poor fliers. Residing as they do +chiefly on the ground, their wings are only required for short +distances, or for raising them or easing their descent from +their roosting-places in forest trees, the shortness of their +wings preventing them from taking extended flights. The +wing-surface of the common swallow is rather more than in the +ratio of two square feet per pound, but having also great length +of pinion, it is both swift and enduring in its flight. When on +a rapid course this bird is in the habit of furling its wings +into a narrow compass. The greater extent of surface is +probably needful for the continual variations of speed and +instant stoppages for obtaining its insect food. + +'On the other hand, there are some birds, particularly of the +duck tribe, whose wing-surface but little exceeds half a square +foot, or seventy-two inches per pound, yet they may be classed +among the strongest and swiftest of fliers. A weight of one +pound, suspended from an area of this extent, would acquire a +velocity due to a fall of sixteen feet--a height sufficient for +the destruction or injury of most animals. But when the plane +is urged forward horizontally, in a manner analogous to the +wings of a bird during flight, the sustaining power is greatly +influenced by the form and arrangement of the surface. + +'In the case of perpendicular descent, as a parachute, the +sustaining effect will be much the same, whatever the figure of +the outline of the superficies may be, and a circle perhaps +affords the best resistance of any. Take, for example, a circle +of twenty square feet (as possessed by the pelican) loaded with +as many pounds. This, as just stated, will limit the rate of +perpendicular descent to 1,320 feet per minute. But instead of +a circle sixty-one inches in diameter, if the area is bounded by +a parallelogram ten feet long by two feet broad, and whilst at +perfect freedom to descend perpendicularly, let a force be +applied exactly in a horizontal direction, so as to carry it +edgeways, with the long side foremost, at a forward speed of +thirty miles per hour--just double that of its passive descent: +the rate of fall under these conditions will be decreased most +remarkably, probably to less than one-fifteenth part, or +eighty-eight feet per minute, or one mile per hour.' + +And again: 'It has before been shown how utterly inadequate the +mere perpendicular impulse of a plane is found to be in +supporting a weight, when there is no horizontal motion at the +time. There is no material weight of air to be acted upon, and +it yields to the slightest force, however great the velocity of +impulse may be. On the other hand, suppose that a large bird, +in full flight, can make forty miles per hour, or 3,520 feet per +minute, and performs one stroke per second. Now, during every +fractional portion of that stroke, the wing is acting upon and +obtaining an impulse from a fresh and undisturbed body of air; +and if the vibration of the wing is limited to an arc of two +feet, this by no means represents the small force of action that +would be obtained when in a stationary position, for the impulse +is secured upon a stratum of fifty-eight feet in length of air +at each stroke. So that the conditions of weight of air for +obtaining support equally well apply to weight of air and its +reaction in producing forward impulse. + +'So necessary is the acquirement of this horizontal speed, even +in commencing flight, that most heavy birds, when possible, rise +against the wind, and even run at the top of their speed to make +their wings available, as in the example of the eagle, mentioned +at the commencement of this paper. It is stated that the Arabs, +on horseback, can approach near enough to spear these birds, +when on the plain, before they are able to rise; their habit is +to perch on an eminence, where possible. + +'The tail of a bird is not necessary for flight. A pigeon can +fly perfectly with this appendage cut short off; it probably +performs an important function in steering, for it is to be +remarked, that most birds that have either to pursue or evade +pursuit are amply provided with this organ. + +'The foregoing reasoning is based upon facts, which tend to show +that the flight of the largest and heaviest of all birds is +really performed with but a small amount of force, and that man +is endowed with sufficient muscular power to enable him also to +take individual and extended flights, and that success is +probably only involved in a question of suitable mechanical +adaptations. But if the wings are to be modelled in imitation +of natural examples, but very little consideration will serve to +demonstrate its utter impracticability when applied in these +forms.' + +Thus Wenham, one of the best theorists of his age. The Society +with which this paper connects his name has done work, between +that time and the present, of which the importance cannot be +overestimated, and has been of the greatest value in the +development of aeronautics, both in theory and experiment. The +objects of the Society are to give a stronger impulse to the +scientific study of aerial navigation, to promote the +intercourse of those interested in the subject at home and +abroad, and to give advice and instruction to those who study +the principles upon which aeronautical science is based. From +the date of its foundation the Society has given special study +to dynamic flight, putting this before ballooning. Its library, +its bureau of advice and information, and its meetings, all +assist in forwarding the study of aeronautics, and its +twenty-three early Annual Reports are of considerable value, +containing as they do a large amount of useful information on +aeronautical subjects, and forming practically the basis of +aeronautical science. + +Ante to Wenham, Stringfellow and the French experimenters +already noted, by some years, was Le Bris, a French sea captain, +who appears to have required only a thorough scientific training +to have rendered him of equal moment in the history of gliding +flight with Lilienthal himself. Le Bris, it appears, watched +the albatross and deduced, from the manner in which it supported +itself in the air, that plane surfaces could be constructed and +arranged to support a man in like manner. Octave Chanute, +himself a leading exponent of gliding, gives the best +description of Le Bris's experiments in a work, Progress in +Flying Machines, which, although published as recently as I +1894, is already rare. Chanute draws from a still rarer book, +namely, De la Landelle's work published in 1884. Le Bris +himself, quoted by De la Landelle as speaking of his first +visioning of human flight, describes how he killed an albatross, +and then--'I took the wing of the albatross and exposed it to +the breeze; and lo! in spite of me it drew forward into the +wind; notwithstanding my resistance it tended to rise. Thus I +had discovered the secret of the bird! I comprehended the whole +mystery of flight.' + +This apparently took place while at sea; later on Le Bris, +returning to France, designed and constructed an artificial +albatross of sufficient size to bear his own weight. The fact +that he followed the bird outline as closely as he did attests +his lack of scientific training for his task, while at the same +time the success of the experiment was proof of his genius. The +body of his artificial bird, boat-shaped, was 13 1/2 ft. in +length, with a breadth of 4 ft. at the widest part. The +material was cloth stretched over a wooden framework; in front +was a small mast rigged after the manner of a ship's masts to +which were attached poles and cords with which Le Bris intended +to work the wings. Each wing was 23 ft. in length, giving a +total supporting surface of nearly 220 sq. ft.; the weight of +the whole apparatus was only 92 pounds. For steering, both +vertical and horizontal, a hinged tail was provided, and the +leading edge of each wing was made flexible. In construction +throughout, and especially in that of the wings, Le Bris adhered +as closely as possible to the original albatross. + +He designed an ingenious kind of mechanism which he termed +'Rotules,' which by means of two levers gave a rotary motion to +the front edge of the wings, and also permitted of their +adjustment to various angles. The inventor's idea was to stand +upright in the body of the contrivance, working the levers and +cords with his hands, and with his feet on a pedal by means of +which the steering tail was to be worked. He anticipated that, +given a strong wind, he could rise into the air after the manner +of an albatross, without any need for flapping his wings, and +the account of his first experiment forms one of the most +interesting incidents in the history of flight. It is related +in full in Chanute's work, from which the present account is +summarised. + +Le Bris made his first experiment on a main road near +Douarnenez, at Trefeuntec. From his observation of the +albatross Le Bris concluded that it was necessary to get some +initial velocity in order to make the machine rise; consequently +on a Sunday morning, with a breeze of about 12 miles an hour +blowing down the road, he had his albatross placed on a cart and +set off, with a peasant driver, against the wind. At the outset +the machine was fastened to the cart by a rope running through +the rails on which the machine rested, and secured by a slip +knot on Le Bris's own wrist, so that only a jerk on his part was +necessary to loosen the rope and set the machine free. On each +side walked an assistant holding the wings, and when a turn of +the road brought the machine full into the wind these men were +instructed to let go, while the driver increased the pace from a +walk to a trot. Le Bris, by pressure on the levers of the +machine, raised the front edges of his wings slightly; they took +the wind almost instantly to such an extent that the horse, +relieved of a great part of the weight he had been drawing, +turned his trot into a gallop. Le Bris gave the jerk of the +rope that should have unfastened the slip knot, but a concealed +nail on the cart caught the rope, so that it failed to run. The +lift of the machine was such, however, that it relieved the +horse of very nearly the weight of the cart and driver, as well +as that of Le Bris and his machine, and in the end the rails of +the cart gave way. Le Bris rose in the air, the machine +maintaining perfect balance and rising to a height of nearly 300 +ft., the total length of the glide being upwards of an eighth of +a mile. But at the last moment the rope which had originally +fastened the machine to the cart got wound round the driver's +body, so that this unfortunate dangled in the air under Le Bris +and probably assisted in maintaining the balance of the +artificial albatross. Le Bris, congratulating himself on his +success, was prepared to enjoy just as long a time in the air as +the pressure of the wind would permit, but the howls of the +unfortunate driver at the end of the rope beneath him dispelled +his dreams; by working his levers he altered the angle of the +front wing edges so skilfully as to make a very successful +landing indeed for the driver, who, entirely uninjured, +disentangled himself from the rope as soon as he touched the +ground, and ran off to retrieve his horse and cart. + +Apparently his release made a difference in the centre of +gravity, for Le Bris could not manipulate his levers for further +ascent; by skilful manipulation he retarded the descent +sufficiently to escape injury to himself; the machine descended +at an angle, so that one wing, striking the ground in front of +the other, received a certain amount of damage. + +It may have been on account of the reluctance of this same or +another driver that Le Bris chose a different method of +launching himself in making a second experiment with his +albatross. He chose the edge of a quarry which had been +excavated in a depression of the ground; here he assembled his +apparatus at the bottom of the quarry, and by means of a rope +was hoisted to a height of nearly 100 ft. from the quarry +bottom, this rope being attached to a mast which he had erected +upon the edge of the depression in which the quarry was +situated. Thus hoisted, the albatross was swung to face a +strong breeze that blew inland, and Le Bris manipulated his +levers to give the front edges of his wings a downward angle, so +that only the top surfaces should take the wing pressure. Having +got his balance, he obtained a lifting angle of incidence on the +wings by means of his levers, and released the hook that secured +the machine, gliding off over the quarry. On the glide he met +with the inevitable upward current of air that the quarry and +the depression in which it was situated caused; this current +upset the balance of the machine and flung it to the bottom of +the quarry, breaking it to fragments. Le Bris, apparently as +intrepid as ingenious, gripped the mast from which his levers +were worked, and, springing upward as the machine touched earth, +escaped with no more damage than a broken leg. But for the +rebound of the levers he would have escaped even this. + +The interest of these experiments is enhanced by the fact that +Le Bris was a seafaring man who conducted them from love of the +science which had fired his imagination, and in so doing +exhausted his own small means. It was in 1855 that he made +these initial attempts, and twelve years passed before his +persistence was rewarded by a public subscription made at Brest +for the purpose of enabling him to continue his experiments. He +built a second albatross, and on the advice of his friends +ballasted it for flight instead of travelling in it himself. It +was not so successful as the first, probably owing to the lack +of human control while in flight; on one of the trials a height +of 150 ft. was attained, the glider being secured by a thin rope +and held so as to face into the wind. A glide of nearly an +eighth of a mile was made with the rope hanging slack, and, at +the end of this distance, a rise in the ground modified the +force of the wind, whereupon the machine settled down without +damage. A further trial in a gusty wind resulted in the +complete destruction of this second machine; Le Bris had no more +funds, no further subscriptions were likely to materialise, and +so the experiments of this first exponent of the art of gliding +(save for Besnier and his kind) came to an end. They +constituted a notable achievement, and undoubtedly Le Bris +deserves a better place than has been accorded him in the ranks +of the early experimenters. + +Contemporary with him was Charles Spencer, the first man to +practice gliding in England. His apparatus consisted of a pair +of wings with a total area of 30 sq. ft., to which a tail and +body were attached. The weight of this apparatus was some 24 +lbs., and, launching himself on it from a small eminence, as was +done later by Lilienthal in his experiments, the inventor made +flights of over 120 feet. The glider in question was exhibited +at the Aeronautical Exhibition of 1868. + + + +VI. THE AGE OF THE GIANTS + +Until the Wright Brothers definitely solved the problem of +flight and virtually gave the aeroplane its present place in +aeronautics, there were three definite schools of experiment. +The first of these was that which sought to imitate nature by +means of the ornithopter or flapping-wing machines directly +imitative of bird flight; the second school was that which +believed in the helicopter or lifting screw; the third and +eventually successful school is that which followed up the +principle enunciated by Cayley, that of opposing a plane surface +to the resistance of the air by supplying suitable motive power +to drive it at the requisite angle for support. + +Engineering problems generally go to prove that too close an +imitation of nature in her forms of recipro-cating motion is not +advantageous; it is impossible to copy the minutiae of a bird's +wing effectively, and the bird in flight depends on the tiniest +details of its feathers just as much as on the general principle +on which the whole wing is constructed. Bird flight, however, +has attracted many experimenters, including even Lilienthal; +among others may be mentioned F. W. Brearey, who invented what +he called the 'Pectoral cord,' which stored energy on each +upstroke of the artificial wing; E. P. Frost; Major R. Moore, +and especially Hureau de Villeneuve, a most enthusiastic student +of this form of flight, who began his experiments about 1865, +and altogether designed and made nearly 300 artificial birds. +one of his later constructions was a machine in bird form with a +wing span of about 50 ft.; the motive power for this was +supplied by steam from a boiler which, being stationary on the +ground, was connected by a length of hose to the machine. De +Villeneuve, turning on steam for his first trial, obtained +sufficient power to make the wings beat very forcibly; with the +inventor on the machine the latter rose several feet into the +air, whereupon de Villeneuve grew nervous and turned off the +steam supply. The machine fell to the earth, breaking one of +its wings, and it does not appear that de Villeneuve troubled to +reconstruct it. This experiment remains as the greatest success +yet achieved by any machine constructed on the ornithopter +principle. + +It may be that, as forecasted by the prophet Wells, the +flapping-wing machine will yet come to its own and compete with +the aeroplane in efficiency. Against this, however, are the +practical advantages of the rotary mechanism of the aeroplane +propeller as compared with the movement of a bird's wing, which, +according to Marey, moves in a figure of eight. The force +derived from a propeller is of necessity continual, while it is +equally obvious that that derived from a flapping movement is +intermittent, and, in the recovery of a wing after completion of +one stroke for the next, there is necessarily a certain +cessation, if not loss, of power. + +The matter of experiment along any lines in connection with +aviation is primarily one of hard cash. Throughout the whole +history of flight up to the outbreak of the European war +development has been handicapped on the score of finance, and, +since the arrival of the aeroplane, both ornithopter and +helicopter schools have been handicapped by this consideration. +Thus serious study of the efficiency of wings in imitation of +those of the living bird has not been carried to a point that +might win success for this method of propulsion. Even Wilbur +Wright studied this subject and propounded certain theories, +while a later and possibly more scientific student, F. W. +Lanchester, has also contributed empirical conclusions. Another +and earlier student was Lawrence Hargrave, who made a +wing-propelled model which achieved successful flight, and in +1885 was exhibited before the Royal Society of New South Wales. +Hargrave called the principle on which his propeller worked that +of a 'Trochoided plane'; it was, in effect, similar to the +feathering of an oar. + +Hargrave, to diverge for a brief while from the machine to the +man, was one who, although he achieved nothing worthy of special +remark, contributed a great deal of painstaking work to the +science of flight. He made a series of experiments with +man-lifting kites in addition to making a study of flapping-wing +flight. It cannot be said that he set forth any new principle; +his work was mainly imitative, but at the same time by +developing ideas originated in great measure by others he helped +toward the solution of the problem. + +Attempts at flight on the helicopter principle consist in the +work of De la Landelle and others already mentioned. The +possibility of flight by this method is modified by a very +definite disadvantage of which lovers of the helicopter seem to +take little account. It is always claimed for a machine of this +type that it possesses great advantages both in rising and in +landing, since, if it were effective, it would obviously be able +to rise from and alight on any ground capable of containing its +own bulk; a further advantage claimed is that the helicopter +would be able to remain stationary in the air, maintaining +itself in any position by the vertical lift of its propeller. + +These potential assets do not take into consideration the fact +that efficiency is required not only in rising, landing, and +remaining stationary in the air, but also in actual flight. It +must be evident that if a certain amount of the motive force is +used in maintaining the machine off the ground, that amount of +force is missing from the total of horizontal driving power. +Again, it is often assumed by advocates of this form of flight +that the rapidity of climb of the helicopter would be far +greater than that of the driven plane; this view overlooks the +fact that the maintenance of aerodynamic support would claim the +greater part of the engine-power; the rate of ascent would be +governed by the amount of power that could be developed surplus +to that required for maintenance. + +This is best explained by actual figures: assuming that a +propeller 15 ft. in diameter is used, almost 50 horse-power +would be required to get an upward lift of 1,000 pounds; this +amount of horse-power would be continually absorbed in +maintaining the machine in the air at any given level; for +actual lift from one level to another at a speed of eleven feet +per second a further 20 horse-power would be required, which +means that 70 horse-power must be constantly provided for; this +absorption of power in the mere maintenance of aero-dynamic +support is a permanent drawback. + +The attraction of the helicopter lies, probably, in the ease +with which flight is demonstrated by means of models constructed +on this principle, but one truism with regard to the principles +of flight is that the problems change remarkably, and often +unexpectedly, with the size of the machine constructed for +experiment. Berriman, in a brief but very interesting manual +entitled Principles of Flight, assumed that 'there is a +significant dimension of which the effective area is an +expression of the second power, while the weight became an +expression of the third power. Then once again we have the +two-thirds power law militating against the successful +construction of large helicopters, on the ground that the +essential weight increases disproportionately fast to the +effective area. From a consideration of the structural features +of propellers it is evident that this particular relationship +does not apply in practice, but it seems reasonable that some +such governing factor should exist as an explanation of the +apparent failure of all full-sized machines that have been +constructed. Among models there is nothing more strikingly +successful than the toy helicopter, in which the essential +weight is so small compared with the effective area.' + +De la Landelle's work, already mentioned, was carried on a few +years later by another Frenchman, Castel, who constructed a +machine with eight propellers arranged in two fours and driven +by a compressed air motor or engine. The model with which +Castel experimented had a total weight of only 49 lbs.; it rose +in the air and smashed itself by driving against a wall, and the +inventor does not seem to have proceeded further. Contemporary +with Castel was Professor Forlanini, whose design was for a +machine very similar to de la Landelle's, with two superposed +screws. This machine ranks as the second on the helicopter +principle to achieve flight; it remained in the air for no less +than the third of a minute in one of its trials. + +Later experimenters in this direction were Kress, a German; +Professor Wellner, an Austrian; and W. R. Kimball, an American. +Kress, like most Germans, set to the development of an idea +which others had originated; he followed de la Landelle and +Forlanini by fitting two superposed propellers revolving in +opposite directions, and with this machine he achieved good +results as regards horse-power to weight; Kimball, it appears, +did not get beyond the rubber-driven model stage, and any +success he may have achieved was modified by the theory +enunciated by Berriman and quoted above. + +Comparing these two schools of thought, the helicopter and +bird-flight schools, it appears that the latter has the greater +chance of eventual success--that is, if either should ever come +into competition with the aeroplane as effective means of +flight. So far, the aeroplane holds the field, but the whole +science of flight is so new and so full of unexpected +developments that this is no reason for assuming that other +means may not give equal effect, when money and brains are +diverted from the driven plane to a closer imitation of natural +flight. + +Reverting from non-success to success, from consideration of the +two methods mentioned above to the direction in which practical +flight has been achieved, it is to be noted that between the +time of Le Bris, Stringfellow, and their contemporaries, and the +nineties of last century, there was much plodding work carried +out with little visible result, more especially so far as +English students were concerned. Among the incidents of those +years is one of the most pathetic tragedies in the whole history +of aviation, that of Alphonse Penaud, who, in his thirty years +of life, condensed the experience of his predecessors and +combined it with his own genius to state in a published patent +what the aeroplane of to-day should be. Consider the following +abstract of Penaud's design as published in his patent of 1876, +and comparison of this with the aeroplane that now exists will +show very few divergences except for those forced on the +inventor by the fact that the internal combustion engine had not +then developed. The double surfaced planes were to be built +with wooden ribs and arranged with a slight dihedral angle; +there was to be a large aspect ratio and the wings were cambered +as in Stringfellow's later models. Provision was made for +warping the wings while in flight, and the trailing edges were +so designed as to be capable of upward twist while the machine +was in the air. The planes were to be placed above the car, and +provision was even made for a glass wind-screen to give +protection to the pilot during flight. Steering was to be +accomplished by means of lateral and vertical planes forming a +tail; these controlled by a single lever corresponding to the +'joy stick' of the present day plane. + +Penaud conceived this machine as driven by two propellers; +alternatively these could be driven by petrol or steam-fed +motor, and the centre of gravity of the machine while in flight +was in the front fifth of the wings. Penaud estimated from 20 to +30 horse-power sufficient to drive this machine, weighing with +pilot and passenger 2,600 lbs., through the air at a speed of 60 +miles an hour, with the wings set at an angle of incidence of +two degrees. So complete was the design that it even included +instruments, consisting of an aneroid, pressure indicator, an +anemometer, a compass, and a level. There, with few +alterations, is the aeroplane as we know it--and Penaud was +twenty-seven when his patent was published. + +For three years longer he worked, experimenting with models, +contributing essays and other valuable data to French papers on +the subject of aeronautics. His gains were ill health, poverty, +and neglect, and at the age of thirty a pistol shot put an end +to what had promised to be one of the most brilliant careers in +all the history of flight. + +Two years before the publication of Penaud's patent Thomas Moy +experimented at the Crystal Palace with a twin-propelled +aeroplane, steam driven, which seems to have failed mainly +because the internal combustion engine had not yet come to give +sufficient power for weight. Moy anchored his machine to a pole +running on a prepared circular track; his engine weighed 80 lbs. +and, developing only three horse-power, gave him a speed of +12 miles an hour. He himself estimated that the machine would +not rise until he could get a speed of 35 miles an hour, and his +estimate was correct. Two six-bladed propellers were placed +side by side between the two main planes of the machine, which +was supported on a triangular wheeled undercarriage and steered +by fairly conventional tail planes. Moy realised that he could +not get sufficient power to achieve flight, but he went on +experimenting in various directions, and left much data +concerning his experiments which has not yet been deemed worthy +of publication, but which still contains a mass of information +that is of practical utility, embodying as it does a vast amount +of painstaking work. + +Penaud and Moy were followed by Goupil, a Frenchman, who, in +place of attempting to fit a motor to an aeroplane, experimented +by making the wind his motor. He anchored his machine to the +ground, allowing it two feet of lift, and merely waited for a +wind to come along and lift it. The machine was stream lined, +and the wings, curving as in the early German patterns of war +aeroplanes, gave a total lifting surface of about 290 sq. ft. +Anchored to the ground and facing a wind of 19 feet per second, +Goupil's machine lifted its own weight and that of two men as +well to the limit of its anchorage. Although this took place as +late as 1883 the inventor went no further in practical work. He +published a book, however, entitled La Locomotion Aerienne, +which is still of great importance, more especially on the +subject of inherent stability. + +In 1884 came the first patents of Horatio Phillips, whose work +lay mainly in the direction of investigation into the curvature +of plane surfaces, with a view to obtaining the greatest amount +of support. Phillips was one of the first to treat the problem +of curvature of planes as a matter for scientific experiment, +and, great as has been the development of the driven plane in +the 36 years that have passed since he began, there is still +room for investigation into the subject which he studied so +persistently and with such valuable result. + +At this point it may be noted that, with the solitary exception +of Le Bris, practically every student of flight had so far set +about constructing the means of launching humanity into the air +without any attempt at ascertaining the nature and peculiarities +of the sustaining medium. The attitude of experimenters in +general might be compared to that of a man who from boyhood had +grown up away from open water, and, at the first sight of an +expanse of water, set to work to construct a boat with a vague +idea that, since wood would float, only sufficient power was +required to make him an efficient navigator. Accident, perhaps, +in the shape of lack of means of procuring driving power, drove +Le Bris to the form of experiment which he actually carried out; +it remained for the later years of the nineteenth century to +produce men who were content to ascertain the nature of the +support the air would afford before attempting to drive +themselves through it. + +Of the age in which these men lived and worked, giving their all +in many cases to the science they loved, even to life itself, it +may be said with truth that 'there were giants on the earth in +those days,' as far as aeronautics is in question. It was an +age of giants who lived and dared and died, venturing into +uncharted space, knowing nothing of its dangers, giving, as a +man gives to his mistress, without stint and for the joy of the +giving. The science of to-day, compared with the glimmerings +that were in that age of the giants, is a fixed and certain +thing; the problems of to-day are minor problems, for the great +major problem vanished in solution when the Wright Brothers made +their first ascent. In that age of the giants was evolved the +flying man, the new type in human species which found full +expression and came to full development in the days of the war, +achieving feats of daring and endurance which leave the +commonplace landsman staggered at thought of that of which his +fellows prove themselves capable. He is a new type, this flying +man, a being of self-forgetfulness; of such was Lilienthal, of +such was Pilcher; of such in later days were Farman, Bleriot, +Hamel, Rolls, and their fellows; great names that will live for +as long as man flies, adventurers equally with those of the +spacious days of Elizabeth. To each of these came the call, and +he worked and dared and passed, having, perhaps, advanced one +little step in the long march that has led toward the perfecting +of flight. + +It is not yet twenty years since man first flew, but into that +twenty years have been compressed a century or so of progress, +while, in the two decades that preceded it, was compressed still +more. We have only to recall and recount the work of four men: +Lilienthal, Langley, Pilcher, and Clement Ader to see the +immense stride that was made between the time when Penaud pulled +a trigger for the last time and the Wright Brothers first left +the earth. Into those two decades was compressed the +investigation that meant knowledge of the qualities of the air, +together with the development of the one prime mover that +rendered flight a possibility--the internal combustion engine. +The coming and progress of this latter is a thing apart, to be +detailed separately; for the present we are concerned with the +evolution of the driven plane, and with it the evolution of that +daring being, the flying man. The two are inseparable, for the +men gave themselves to their art; the story of Lilienthal's life +and death is the story of his work; the story of Pilcher's work +is that of his life and death. + +Considering the flying man as he appeared in the war period, +there entered into his composition a new element--patriotism-- +which brought about a modification of the type, or, perhaps, made +it appear that certain men belonged to the type who in reality +were commonplace mortals, animated, under normal conditions, by +normal motives, but driven by the stress of the time to take rank +with the last expression of human energy, the flying type. +However that may be, what may be termed the mathematising of +aeronautics has rendered the type itself evanescent; your pilot +of to-day knows his craft, once he is trained, much in the manner +that a driver of a motor-lorry knows his vehicle; design has been +systematised, capabilities have been tabulated; camber, dihedral +angle, aspect ratio, engine power, and plane surface, are +business items of drawing office and machine shop; there is room +for enterprise, for genius, and for skill; once and again there +is room for daring, as in the first Atlantic flight. Yet that +again was a thing of mathematical calculation and petrol storage, +allied to a certain stark courage which may be found even in +landsmen. For the ventures into the unknown, the limit of +daring, the work for work's sake, with the almost certainty that +the final reward was death, we must look back to the age of the +giants, the age when flying was not a business, but romance. + + + +VII. LILIENTHAL AND PILCHER + +There was never a more enthusiastic and consistent student of +the problems of flight than Otto Lilienthal, who was born in +1848 at Anklam, Pomerania, and even from his early school-days +dreamed and planned the conquest of the air. His practical +experiments began when, at the age of thirteen, he and his +brother Gustav made wings consisting of wooden framework covered +with linen, which Otto attached to his arms, and then ran +downhill flapping them. In consequence of possible derision on +the part of other boys, Otto confined these experiments for the +most part to moonlit nights, and gained from them some idea of +the resistance offered by flat surfaces to the air. It was in +1867 that the two brothers began really practical work, +experimenting with wings which, from their design, indicate some +knowledge of Besnier and the history of his gliding experiments; +these wings the brothers fastened to their backs, moving them +with their legs after the fashion of one attempting to swim. +Before they had achieved any real success in gliding the +Franco-German war came as an interruption; both brothers served +in this campaign, resuming their experiments in 1871 at the +conclusion of hostilities. + +The experiments made by the brothers previous to the war had +convinced Otto that previous experimenters in gliding flight had +failed through reliance on empirical conclusions or else through +incomplete observation on their own part, mostly of bird flight. +From 1871 onward Otto Lilenthal (Gustav's interest in the +problem was not maintained as was his brother's) made what is +probably the most detailed and accurate series of observations +that has ever been made with regard to the properties of curved +wing surfaces. So far as could be done, Lilienthal tabulated +the amount of air resistance offered to a bird's wing, +ascertaining that the curve is necessary to flight, as offering +far more resistance than a flat surface. Cayley, and others, +had already stated this, but to Lilienthal belongs the honour of +being first to put the statement to effective proof--he made +over 2,000 gliding flights between 1891 and the regrettable end +of his experiments; his practical conclusions are still regarded +as part of the accepted theory of students of flight. In 1889 +he published a work on the subject of gliding flight which +stands as data for investigators, and, on the conclusions +embodied in this work, he began to build his gliders and +practice what he had preached, turning from experiment with +models to wings that he could use. + +It was in the summer of 1891 that he built his first glider of +rods of peeled willow, over which was stretched strong cotton +fabric; with this, which had a supporting surface of about 100 +square feet, Otto Lilienthal launched himself in the air from a +spring board, making glides which, at first of only a few feet, +gradually lengthened. As his experience of the supporting +qualities of the air progressed he gradually altered his designs +until, when Pilcher visited him in the spring of 1895, he +experimented with a glider, roughly made of peeled willow rods +and cotton fabric, having an area of 150 square feet and +weighing half a hundredweight. By this time Lilienthal had +moved from his springboard to a conical artificial hill which he +had had thrown up on level ground at Grosse Lichterfelde, near +Berlin. This hill was made with earth taken from the +excavations incurred in constructing a canal, and had a cave +inside in which Lilienthal stored his machines. Pilcher, in his +paper on 'Gliding,' [*] gives an excellent short summary of +Lilienthal's experiments, from which the following extracts are +taken:-- + +[*] Aeronautical Classes, No. 5. Royal Aeronautical Society's +publications. + +'At first Lilienthal used to experiment by jumping off a +springboard with a good run. Then he took to practicing on some +hills close to Berlin. In the summer of 1892 he built a +flat-roofed hut on the summit of a hill, from the top of which +he used to jump, trying, of course, to soar as far as possible +before landing.... One of the great dangers with a soaring +machine is losing forward speed, inclining the machine too much +down in front, and coming down head first. Lilienthal was the +first to introduce the system of handling a machine in the air +merely by moving his weight about in the machine; he always +rested only on his elbows or on his elbows and shoulders.... + +'In 1892 a canal was being cut, close to where Lilienthal lived, +in the suburbs of Berlin, and with the surplus earth Lilienthal +had a special hill thrown up to fly from. The country round is +as flat as the sea, and there is not a house or tree near it to +make the wind unsteady, so this was an ideal practicing ground; +for practicing on natural hills is generally rendered very +difficult by shifty and gusty winds.... This hill is 50 feet +high, and conical. Inside the hill there is a cave for the +machines to be kept in.... When Lilienthal made a good flight he +used to land 300 feet from the centre of the hill, having come +down at an angle of 1 in 6; but his best flights have been at an +angle of about 1 in 10. + +'If it is calm, one must run a few steps down the hill, holding +the machine as far back on oneself as possible, when the air +will gradually support one, and one slides off the hill into the +air. If there is any wind, one should face it at starting; to +try to start with a side wind is most unpleasant. It is +possible after a great deal of practice to turn in the air, and +fairly quickly. This is accomplished by throwing one's weight +to one side, and thus lowering the machine on that side towards +which one wants to turn. Birds do the same thing-- crows and +gulls show it very clearly. Last year Lilienthal chiefly +experimented with double-surfaced machines. These were very +much like the old machines with awnings spread above them. + +'The object of making these double-surfaced machines was to get +more surface without increasing the length and width of the +machine. This, of course, it does, but I personally object to +any machine in which the wing surface is high above the weight. +I consider that it makes the machine very difficult to handle in +bad weather, as a puff of wind striking the surface, high above +one, has a great tendency to heel the machine over. + +'Herr Lilienthal kindly allowed me to sail down his hill in one +of these double-surfaced machines last June. With the great +facility afforded by his conical hill the machine was handy +enough; but I am afraid I should not be able to manage one at +all in the squally districts I have had to practice in over +here. + +'Herr Lilienthal came to grief through deserting his old method +of balancing. In order to control his tipping movements more +rapidly he attached a line from his horizontal rudder to his +head, so that when he moved his head forward it would lift the +rudder and tip the machine up in front, and vice versa. He was +practicing this on some natural hills outside Berlin, and he +apparently got muddled with the two motions, and, in trying to +regain speed after he had, through a lull in the wind, come to +rest in the air, let the machine get too far down in front, came +down head first and was killed.' + +Then in another passage Pilcher enunciates what is the true +value of such experiments as Lilienthal--and, subsequently, he +himself--made: 'The object of experimenting with soaring +machines,' he says, 'is to enable one to have practice in +starting and alighting and controlling a machine in the air. +They cannot possibly float horizontally in the air for any +length of time, but to keep going must necessarily lose in +elevation. They are excellent schooling machines, and that is +all they are meant to be, until power, in the shape of an engine +working a screw propeller, or an engine working wings to drive +the machine forward, is added; then a person who is used to +soaring down a hill with a simple soaring machine will be able +to fly with comparative safety. One can best compare them to +bicycles having no cranks, but on which one could learn to +balance by coming down an incline.' + +It was in 1895 that Lilienthal passed from experiment with the +monoplane type of glider to the construction of a biplane glider +which, according to his own account, gave better results than +his previous machines. 'Six or seven metres velocity of wind,' +he says, 'sufficed to enable the sailing surface of 18 square +metres to carry me almost horizontally against the wind from the +top of my hill without any starting jump. If the wind is +stronger I allow myself to be simply lifted from the point of +the hill and to sail slowly towards the wind. The direction of +the flight has, with strong wind, a strong upwards tendency. I +often reach positions in the air which are much higher than my +starting point. At the climax of such a line of flight I +sometimes come to a standstill for some time, so that I am +enabled while floating to speak with the gentlemen who wish to +photograph me, regarding the best position for the +photographing.' + +Lilienthal's work did not end with simple gliding, though he did +not live to achieve machine-driven flight. Having, as he +considered, gained sufficient experience with gliders, he +constructed a power-driven machine which weighed altogether +about 90 lbs., and this was thoroughly tested. The extremities +of its wings were made to flap, and the driving power was +obtained from a cylinder of compressed carbonic acid gas, +released through a hand-operated valve which, Lilienthal +anticipated, would keep the machine in the air for four minutes. +There were certain minor accidents to the mechanism, which +delayed the trial flights, and on the day that Lilienthal had +determined to make his trial he made a long gliding flight with +a view to testing a new form of rudder that--as Pilcher +relates--was worked by movements of his head. His death came +about through the causes that Pilcher states; he fell from a +height of 50 feet, breaking his spine, and the next day he died. + +It may be said that Lilienthal accomplished as much as any one +of the great pioneers of flying. As brilliant in his +conceptions as da Vinci had been in his, and as conscientious a +worker as Borelli, he laid the foundations on which Pilcher, +Chanute, and Professor Montgomery were able to build to such +good purpose. His book on bird flight, published in 1889, with +the authorship credited both to Otto and his brother Gustav, is +regarded as epoch-making; his gliding experiments are no less +entitled to this description. + +In England Lilienthal's work was carried on by Percy Sinclair +Pilcher, who, born in 1866, completed six years' service in the +British Navy by the time that he was nineteen, and then went +through a course of engineering, subsequently joining Maxim in +his experimental work. It was not until 1895 that he began +to build the first of the series of gliders with which he earned +his plane among the pioneers of flight. Probably the best +account of Pilcher's work is that given in the Aeronautical +Classics issued by the Royal Aeronautical Society, from which +the following account of Pilcher's work is mainly abstracted.[*] + +[*] Aeronautical Classes, No. 5. Royal Aeronautical Society +publications. + +The 'Bat,' as Pilcher named his first glider, was a monoplane +which he completed before he paid his visit to Lilienthal in +1895. Concerning this Pilcher stated that he purposely finished +his own machine before going to see Lilienthal, so as to get the +greatest advantage from any original ideas he might have; he was +not able to make any trials with this machine, however, until +after witnessing Lilienthal's experiments and making several +glides in the biplane glider which Lilienthal constructed. + + +The wings of the 'Bat' formed a pronounced dihedral angle; the +tips being raised 4 feet above the body. The spars forming the +entering edges of the wings crossed each other in the centre and +were lashed to opposite sides of the triangle that served as a +mast for the stay-wires that guyed the wings. The four ribs of +each wing, enclosed in pockets in the fabric, radiated fanwise +from the centre, and were each stayed by three steel piano-wires +to the top of the triangular mast, and similarly to its base. +These ribs were bolted down to the triangle at their roots, and +could be easily folded back on to the body when the glider was +not in use. A small fixed vertical surface was carried in the +rear. The framework and ribs were made entirely of Riga pine; +the surface fabric was nainsook. The area of the machine was +150 square feet; its weight 45 lbs.; so that in flight, with +Pilcher's weight of 145 lbs. added, it carried one and a half +pounds to the square foot. + +Pilcher's first glides, which he carried out on a grass hill on +the banks of the Clyde near Cardross, gave little result, owing +to the exaggerated dihedral angle of the wings, and the absence +of a horizontal tail. The 'Bat 'was consequently reconstructed +with a horizontal tail plane added to the vertical one, and with +the wings lowered so that the tips were only six inches above +the level of the body. The machine now gave far better results; +on the first glide into a head wind Pilcher rose to a height of +twelve feet and remained in the the air for a third of a minute; +in the second attempt a rope was used to tow the glider, which +rose to twenty feet and did not come to earth again until nearly +a minute had passed. With experience Pilcher was able to +lengthen his glide and improve his balance, but the dropped wing +tips made landing difficult, and there were many breakages. + +In consequence of this Pilcher built a second glider which he +named the 'Beetle,' because, as he said, it looked like one. In +this the square-cut wings formed almost a continuous plane, +rigidly fixed to the central body, which consisted of a shaped +girder. These wings were built up of five transverse bamboo +spars, with two shaped ribs running from fore to aft of each +wing, and were stayed overhead to a couple of masts. The tail, +consisting of two discs placed crosswise (the horizontal one +alone being movable), was carried high up in the rear. With the +exception of the wing-spars, the whole framework was built of +white pine. The wings in this machine were actually on a higher +level than the operator's head; the centre of gravity was, +consequently, very low, a fact which, according to Pilcher's own +account, made the glider very difficult to handle. Moreover, the +weight of the 'Beetle,' 80 lbs., was considerable; the body had +been very solidly built to enable it to carry the engine which +Pilcher was then contemplating; so that the glider carried some +225 lbs. with its area of 170 square feet--too great a mass for +a single man to handle with comfort. + +It was in the spring of 1896 that Pilcher built his third +glider, the 'Gull,' with 300 square feet of area and a weight of +55 lbs. The size of this machine rendered it unsuitable for +experiment in any but very calm weather, and it incurred such +damage when experiments were made in a breeze that Pilcher found +it necessary to build a fourth, which he named the 'Hawk.' This +machine was very soundly built, being constructed of bamboo, +with the exception of the two main transverse beams. The wings +were attached to two vertical masts, 7 feet high, and 8 feet +apart, joined at their summits and their centres by two wooden +beams. Each wing had nine bamboo ribs, radiating from its mast, +which was situated at a distance of 2 feet 6 inches from the +forward edge of the wing. Each rib was rigidly stayed at the +top of the mast by three tie-wires, and by a similar number to +the bottom of the mast, by which means the curve of each wing +was maintained uniformly. The tail was formed of a triangular +horizontal surface to which was affixed a triangular vertical +surface, and was carried from the body on a high bamboo mast, +which was also stayed from the masts by means of steel wires, +but only on its upper surface, and it was the snapping of one of +these guy wires which caused the collapse of the tail support +and brought about the fatal end of Pilcher's experiments. In +flight, Pilcher's head, shoulders, and the greater part of his +chest projected above the wings. He took up his position by +passing his head and shoulders through the top aperture formed +between the two wings, and resting his forearms on the +longitudinal body members. A very simple form of undercarriage, +which took the weight off the glider on the ground, was fitted, +consisting of two bamboo rods with wheels suspended on steel +springs. + +Balance and steering were effected, apart from the high degree +of inherent stability afforded by the tail, as in the case of +Lilienthal's glider, by altering the position of the body. With +this machine Pilcher made some twelve glides at Eynsford in Kent +in the summer of 1896, and as he progressed he increased the +length of his glides, and also handled the machine more easily, +both in the air and in landing. He was occupied with plans for +fitting an engine and propeller to the 'Hawk,' but, in these +early days of the internal combustion engine, was unable to get +one light enough for his purpose. There were rumours of an +engine weighing 15 lbs. which gave 1 horse-power, and was +reported to be in existence in America, but it could not be +traced. + +In the spring of 1897 Pilcher took up his gliding experiments +again, obtaining what was probably the best of his glides on +June 19th, when he alighted after a perfectly balanced glide of +over 250 yards in length, having crossed a valley at a +considerable height. From his various experiments he concluded +that once the machine was launched in the air an engine of, at +most, 3 horse-power would suffice for the maintenance of +horizontal flight, but he had to allow for the additional weight +of the engine and propeller, and taking into account the +comparative inefficiency of the propeller, he planned for an +engine of 4 horse-power. Engine and propeller together were +estimated at under 44 lbs. weight, the engine was to be fitted +in front of the operator, and by means of an overhead shaft was +to operate the propeller situated in rear of the wings. 1898 +went by while this engine was under construction. Then in 1899 +Pilcher became interested in Lawrence Hargrave's soaring kites, +with which he carried out experiments during the summer of 1899. +It is believed that he intended to incorporate a number of these +kites in a new machine, a triplane, of which the fragments +remaining are hardly sufficient to reconstitute the complete +glider. This new machine was never given a trial. For on +September 30th, 1899, at Stamford Hall, Market Harborough, +Pilcher agreed to give a demonstration of gliding flight, but +owing to the unfavourable weather he decided to postpone the +trial of the new machine and to experiment with the 'Hawk,' +which was intended to rise from a level field, towed by a line +passing over a tackle drawn by two horses. At the first trial +the machine rose easily, but the tow-line snapped when it was +well clear of the ground, and the glider descended, weighed down +through being sodden with rain. Pilcher resolved on a second +trial, in which the glider again rose easily to about thirty +feet, when one of the guy wires of the tail broke, and the tail +collapsed; the machine fell to the ground, turning over, and +Pilcher was unconscious when he was freed from the wreckage. + +Hopes were entertained of his recovery, but he died on Monday, +October 2nd, 1899, aged only thirty-four. His work in the cause +of flying lasted only four years, but in that time his actual +accomplishments were sufficient to place his name beside that of +Lilienthal, with whom he ranks as one of the greatest exponents +of gliding flight. + + + +VIII. AMERICAN GLIDING EXPERIMENTS + +While Pilcher was carrying on Lilienthal's work in England, the +great German had also a follower in America; one Octave Chanute, +who, in one of the statements which he has left on the subject +of his experiments acknowledges forty years' interest in the +problem of flight, did more to develop the glider in America +than--with the possible exception of Montgomery--any other man. +Chanute had all the practicality of an American; he began his +work, so far as actual gliding was concerned, with a full-sized +glider of the Lilienthal type, just before Lilienthal was +killed. In a rather rare monograph, entitled Experiments in +Flying, Chanute states that he found the Lilienthal glider +hazardous and decided to test the value of an idea of his own; +in this he followed the same general method, but reversed the +principle upon which Lilienthal had depended for maintaining his +equilibrium in the air. Lilienthal had shifted the weight of +his body, under immovable wings, as fast and as far as the +sustaining pressure varied under his surfaces; this shifting was +mainly done by moving the feet, as the actions required were +small except when alighting. Chanute's idea was to have the +operator remain seated in the machine in the air, and to +intervene only to steer or to alight; moving mechanism was +provided to adjust the wings automatically in order to restore +balance when necessary. + +Chanute realised that experiments with models were of little +use; in order to be fully instructive, these experiments should +be made with a full-sized machine which carried its operator, +for models seldom fly twice alike in the open air, and no +relation can be gained from them of the divergent air currents +which they have experienced. Chanute's idea was that any flying +machine which might be constructed must be able to operate in a +wind; hence the necessity for an operator to report upon what +occurred in flight, and to acquire practical experience of the +work of the human factor in imitation of bird flight. From this +point of view he conducted his own experiments; it must be noted +that he was over sixty years of age when he began, and, being no +longer sufficiently young and active to perform any but short +and insignificant glides, the courage of the man becomes all the +more noteworthy; he set to work to evolve the state required by +the problem of stability, and without any expectation of +advancing to the construction of a flying machine which might be +of commercial value. His main idea was the testing of devices +to secure equilibrium; for this purpose he employed assistants +to carry out the practical work, where he himself was unable to +supply the necessary physical energy. + +Together with his assistants he found a suitable place for +experiments among the sandhills on the shore of Lake Michigan, +about thirty miles eastward from Chicago. Here a hill about +ninety-five feet high was selected as a point from which +Chanute's gliders could set off; in practice, it was found that +the best observation was to be obtained from short glides at +low speed, and, consequently, a hill which was only sixty-one +feet above the shore of the lake was employed for the +experimental work done by the party. + +In the years 1896 and 1897, with parties of from four to six +persons, five full-sized gliders were tried out, and from these +two distinct types were evolved: of these one was a machine +consisting of five tiers of wings and a steering tail, and the +other was of the biplane type; Chanute believed these to be +safer than any other machine previously evolved, solving, as he +states in his monograph, the problem of inherent equilibrium as +fully as this could be done. Unfortunately, very few +photographs were taken of the work in the first year, but one +view of a multiple wing-glider survives, showing the machine in +flight. In 1897 a series of photographs was taken exhibiting +the consecutive phases of a single flight; this series of +photographs represents the experience gained in a total of about +one thousand glides, but the point of view was varied so as to +exhibit the consecutive phases of one single flight. + +The experience gained is best told in Chanute's own words. 'The +first thing,' he says, 'which we discovered practically was that +the wind flowing up a hill-side is not a steadily-flowing +current like that of a river. It comes as a rolling mass, full +of tumultuous whirls and eddies, like those issuing from a +chimney; and they strike the apparatus with constantly varying +force and direction, sometimes withdrawing support when most +needed. It has long been known, through instrumental +observations, that the wind is constantly changing in force and +direction; but it needed the experience of an operator afloat on +a gliding machine to realise that this all proceeded from +cyclonic action; so that more was learned in this respect in a +week than had previously been acquired by several years of +experiments with models. There was a pair of eagles, living in +the top of a dead tree about two miles from our tent, that came +almost daily to show us how such wind effects are overcome and +utilised. The birds swept in circles overhead on pulseless +wings, and rose high up in the air. Occasionally there was a +side-rocking motion, as of a ship rolling at sea, and then the +birds rocked back to an even keel; but although we thought the +action was clearly automatic, and were willing to learn, our +teachers were too far off to show us just how it was done, and +we had to experiment for ourselves.' + +Chanute provided his multiple glider with a seat, but, since +each glide only occupied between eight and twelve seconds, there +was little possibility of the operator seating himself. With +the multiple glider a pair of horizontal bars provided rest for +the arms, and beyond these was a pair of vertical bars which the +operator grasped with his hands; beyond this, the operator was +in no way attached to the machine. He took, at the most, four +running steps into the wind, which launched him in the air, and +thereupon he sailed into the wind on a generally descending +course. In the matter of descent Chanute observed the sparrow +and decided to imitate it. 'When the latter,' he says, +'approaches the street, he throws his body back, tilts his +outspread wings nearly square to the course, and on the cushion +of air thus encountered he stops his speed and drops lightly to +the ground. So do all birds. We tried it with misgivings, but +found it perfectly effective. The soft sand was a great +advantage, and even when the experts were racing there was not a +single sprained ankle.' + +With the multiple winged glider some two to three hundred glides +were made without any accident either to the man or to the +machine, and the action was found so effective, the principle so +sound, that full plans were published for the benefit of any +experimenters who might wish to improve on this apparatus. The +American Aeronautical Annual for 1897 contains these plans; +Chanute confessed that some movement on the part of the operator +was still required to control the machine, but it was only a +seventh or a sixth part of the movement required for control of +the Lilienthal type. + +Chanute waxed enthusiastic over the possibilities of gliding, +concerning which he remarks that 'There is no more delightful +sensation than that of gliding through the air. All the +faculties are on the alert, and the motion is astonishingly +smooth and elastic. The machine responds instantly to the +slightest movement of the operator; the air rushes by one's +ears; the trees and bushes flit away underneath, and the landing +comes all too quickly. Skating, sliding, and bicycling are not +to be compared for a moment to aerial conveyance, in which, +perhaps, zest is added by the spice of danger. For it must be +distinctly understood that there is constant danger in such +preliminary experiments. When this hazard has been eliminated +by further evolution, gliding will become a most popular sport.' + +Later experiments proved that the biplane type of glider gave +better results than the rather cumbrous model consisting of five +tiers of planes. Longer and more numerous glides, to the number +of seven to eight hundred, were obtained, the rate of descent +being about one in six. The longest distance traversed was +about 120 yards, but Chanute had dreams of starting from a hill +about 200 feet high, which would have given him gliding flights +of 1,200 feet. He remarked that 'In consequence of the speed +gained by running, the initial stage of the flight is nearly +horizontal, and it is thrilling to see the operator pass from +thirty to forty feet overhead, steering his machine, undulating +his course, and struggling with the wind-gusts which whistle +through the guy wires. The automatic mechanism restores the +angle of advance when compromised by variations of the breeze; +but when these come from one side and tilt the apparatus, the +weight has to be shifted to right the machine... these gusts +sometimes raise the machine from ten to twenty feet vertically, +and sometimes they strike the apparatus from above, causing it +to descend suddenly. When sailing near the ground, these +vicissitudes can be counteracted by movements of the body from +three to four inches; but this has to be done instantly, for +neither wings nor gravity will wait on meditation. At a height +of three hundred or four hundred feet the regulating mechanism +would probably take care of these wind-gusts, as it does, in +fact, for their minor variations. The speed of the machine is +generally about seventeen miles an hour over the ground, and +from twenty-two to thirty miles an hour relative to the air. +Constant effort was directed to keep down the velocity, which +was at times fifty-two miles an hour. This is the purpose of +the starting and gliding against the wind, which thus furnishes +an initial velocity without there being undue speed at the +landing. The highest wind we dared to experiment in blew at +thirty-one miles an hour; when the wind was stronger, we waited +and watched the birds.' + +Chanute details an amusing little incident which occurred in the +course of experiment with the biplane glider. He says that 'We +had taken one of the machines to the top of the hill, and loaded +its lower wings with sand to hold it while we e went to lunch. +A gull came strolling inland, and flapped full-winged to +inspect. He swept several circles above the machine, stretched +his neck, gave a squawk and went off. Presently he returned +with eleven other gulls, and they seemed to hold a conclave +about one hundred feet above the big new white bird which they +had discovered on the sand. They circled round after round, and +once in a while there was a series of loud peeps, like those of +a rusty gate, as if in conference, with sudden flutterings, as +if a terrifying suggestion had been made. The bolder birds +occasionally swooped downwards to inspect the monster more +closely; they twisted their heads around to bring first one eye +and then the other to bear, and then they rose again. After +some seven or eight minutes of this performance, they evidently +concluded either that the stranger was too formidable to tackle, +if alive, or that he was not good to eat, if dead, and they flew +off to resume fishing, for the weak point about a bird is his +stomach.' + +The gliders were found so stable, more especially the biplane +form, that in the end Chanute permitted amateurs to make trials +under guidance, and throughout the whole series of experiments +not a single accident occurred. Chanute came to the conclusion +that any young, quick, and handy man could master a gliding +machine almost as soon as he could get the hang of a bicycle, +although the penalty for any mistake would be much more severe. + +At the conclusion of his experiments he decided that neither the +multiple plane nor the biplane type of glider was sufficiently +perfected for the application of motive power. In spite of the +amount of automatic stability that he had obtained he considered +that there was yet more to be done, and he therefore advised +that every possible method of securing stability and safety +should be tested, first with models, and then with full-sized +machines; designers, he said, should make a point of practice in +order to make sure of the action, to proportion and adjust the +parts of their machine, and to eliminate hidden defects. +Experimental flight, he suggested, should be tried over water, +in order to break any accidental fall; when a series of +experiments had proved the stability of a glider, it would then +be time to apply motive power. He admitted that such a process +would be both costly and slow, but, he said, that 'it greatly +diminished the chance of those accidents which bring a whole +line of investigation into contempt.' He saw the flying machine +as what it has, in fact, been; a child of evolution, carried on +step by step by one investigator after another, through the +stages of doubt and perplexity which lie behind the realm of +possibility, beyond which is the present day stage of actual +performance and promise of ultimate success and triumph over the +earlier, more cumbrous, and slower forms of the transport that +we know. + +Chanute's monograph, from which the foregoing notes have been +comprised, was written soon after the conclusion of his series +of experiments. He does not appear to have gone in for further +practical work, but to have studied the subject from a +theoretical view-point and with great attention to the work done +by others. In a paper contributed in 1900 to the American +Independent, he remarks that 'Flying machines promise better +results as to speed, but yet will be of limited commercial +application. They may carry mails and reach other inaccessible +places, but they cannot compete with railroads as carriers of +passengers or freight. They will not fill the heavens with +commerce, abolish custom houses, or revolutionise the world, for +they will be expensive for the loads which they can carry, and +subject to too many weather contingencies. Success is, however, +probable. Each experimenter has added something to previous +knowledge which his successors can avail of. It now seems +likely that two forms of flying machines, a sporting type and an +exploration type, will be gradually evolved within one or two +generations, but the evolution will be costly and slow, and must +be carried on by well-equipped and thoroughly informed +scientific men; for the casual inventor, who relies upon one or +two happy inspirations, will have no chance of success +whatever.' + +Follows Professor John J. Montgomery, who, in the true American +spirit, describes his own experiments so well that nobody can +possibly do it better. His account of his work was given first +of all in the American Journal, Aeronautics, in January, 1909, +and thence transcribed in the English paper of the same name in +May, 1910, and that account is here copied word for word. It +may, however, be noted first that as far back as 1860, when +Montgomery was only a boy, he was attracted to the study of +aeronautical problems, and in 1883 he built his first machine, +which was of the flapping-wing ornithopter type, and which +showed its designer, with only one experiment, that he must +design some other form of machine if he wished to attain to a +successful flight. Chanute details how, in 1884 and 1885 +Montgomery built three gliders, demonstrating the value of +curved surfaces. With the first of these gliders Montgomery +copied the wing of a seagull; with the second he proved that a +flat surface was virtually useless, and with the third he +pivoted his wings as in the Antoinette type of power-propelled +aeroplane, proving to his own satisfaction that success lay in +this direction. His own account of the gliding flights carried +out under his direction is here set forth, being the best +description of his work that can be obtained:-- + +'When I commenced practical demonstration in my work with +aeroplanes I had before me three points; first, equilibrium; +second, complete control; and third, long continued or soaring +flight. In starting I constructed and tested three sets of +models, each in advance of the other in regard to the +continuance of their soaring powers, but all equally perfect as +to equilibrium and control. These models were tested by +dropping them from a cable stretched between two mountain tops, +with various loads, adjustments and positions. And it made no +difference whether the models were dropped upside down or any +other conceivable position, they always found their equilibrium +immediately and glided safely to earth. + +'Then I constructed a large machine patterned after the first +model, and with the assistance of three cowboy friends +personally made a number of flights in the steep mountains near +San Juan (a hundred miles distant). In making these flights I +simply took the aeroplane and made a running jump. These tests +were discontinued after I put my foot into a squirrel hole in +landing and hurt my leg. + +'The following year I commenced the work on a larger scale, by +engaging aeronauts to ride my aeroplane dropped from balloons. +During this work I used five hot-air balloons and one gas +balloon, five or six aeroplanes, three riders--Maloney, Wilkie, +and Defolco--and had sixteen applicants on my list, and had a +training station to prepare any when I needed them. + +'Exhibitions were given in Santa Cruz, San Jose, Santa Clara, +Oaklands, and Sacramento. The flights that were made, instead +of being haphazard affairs, were in the order of safety and +development. In the first flight of an aeronaut the aeroplane +was so arranged that the rider had little liberty of action, +consequently he could make only a limited flight. In some of +the first flights, the aeroplane did little more than settle in +the air. But as the rider gained experience in each successive +flight I changed the adjustments, giving him more liberty of +action, so he could obtain longer flights and more varied +movements in the flights. But in none of the flights did I have +the adjustments so that the riders had full liberty, as I did +not consider that they had the requisite knowledge and +experience necessary for their safety; and hence, none of my +aeroplanes were launched so arranged that the rider could make +adjustments necessary for a full flight. + +'This line of action caused a good deal of trouble with +aeronauts or riders, who had unbounded confidence and wanted to +make long flights after the first few trials; but I found it +necessary, as they seemed slow in comprehending the important +elements and were willing to take risks. To give them the full +knowledge in these matters I was formulating plans for a large +starting station on the Mount Hamilton Range from which I could +launch an aeroplane capable of carrying two, one of my aeronauts +and myself, so I could teach him by demonstration. But the +disasters consequent on the great earthquake completely stopped +all my work on these lines. The flights that were given were +only the first of the series with aeroplanes patterned after the +first model. There were no aeroplanes constructed according to +the two other models, as I had not given the full demonstration +of the workings of the first, though some remarkable and +startling work was done. On one occasion Maloney, in trying to +make a very short turn in rapid flight, pressed very hard on the +stirrup which gives a screw-shape to the wings, and made a side +somersault. The course of the machine was very much like one +turn of a corkscrew. After this movement the machine continued +on its regular course. And afterwards Wilkie, not to be outdone +by Maloney, told his friends he would do the same, and in a +subsequent flight made two side somersaults, one in one +direction and the other in an opposite, then made a deep dive +and a long glide, and, when about three hundred feet in the air, +brought the aeroplane to a sudden stop and settled to the earth. +After these antics, I decreased the extent of the possible +change in the form of wing-surface, so as to allow only straight +sailing or only long curves in turning. + +'During my work I had a few carping critics that I silenced by +this standing offer: If they would deposit a thousand dollars I +would cover it on this proposition. I would fasten a 150 pound +sack of sand in the rider's seat, make the necessary +adjustments, and send up an aeroplane upside down with a +balloon, the aeroplane to be liberated by a time fuse. If the +aeroplane did not immediately right itself, make a flight, and +come safely to the ground, the money was theirs. + +'Now a word in regard to the fatal accident. The circumstances +are these: The ascension was given to entertain a military +company in which were many of Maloney's friends, and he had told +them he would give the most sensational flight they ever heard +of. As the balloon was rising with the aeroplane, a guy rope +dropping switched around the right wing and broke the tower that +braced the two rear wings and which also gave control over the +tail. We shouted Maloney that the machine was broken, but he +probably did not hear us, as he was at the same time saying, +"Hurrah for Montgomery's airship," and as the break was behind +him, he may not have detected it. Now did he know of the +breakage or not, and if he knew of it did he take a risk so as +not to disappoint his friends? At all events, when the machine +started on its flight the rear wings commenced to flap (thus +indicating they were loose), the machine turned on its back, and +settled a little faster than a parachute. When we reached +Maloney he was unconscious and lived only thirty minutes. The +only mark of any kind on him was a scratch from a wire on the +side of his neck. The six attending physicians were puzzled at +the cause of his death. This is remarkable for a vertical +descent of over 2,000 feet.' + +The flights were brought to an end by the San Francisco +earthquake in April, 1906, which, Montgomery states, 'Wrought +such a disaster that I had to turn my attention to other +subjects and let the aeroplane rest for a time.' Montgomery +resumed experiments in 1911 in California, and in October of +that year an accident brought his work to an end. The report in +the American Aeronautics says that 'a little whirlwind caught +the machine and dashed it head on to the ground; Professor +Montgomery landed on his head and right hip. He did not believe +himself seriously hurt, and talked with his year-old bride in +the tent. He complained of pains in his back, and continued to +grow worse until he died.' + + + +IX. NOT PROVEN + +The early history of flying, like that of most sciences, is +replete with tragedies; in addition to these it contains one +mystery concerning Clement Ader, who was well known among +European pioneers in the development of the telephone, and first +turned his attention to the problems of mechanical flight in +1872. At the outset he favoured the ornithopter principle, +constructing a machine in the form of a bird with a wing-spread +of twenty-six feet; this, according to Ader's conception, was to +fly through the efforts of the operator. The result of such an +attempt was past question and naturally the machine never left +the ground. + +A pause of nineteen years ensued, and then in 1886 Ader turned +his mind to the development of the aeroplane, constructing a +machine of bat-like form with a wingspread of about forty-six +feet, a weight of eleven hundred pounds, and a steam-power plant +of between twenty and thirty horse-power driving a four-bladed +tractor screw. On October 9th, 1890, the first trials of this +machine were made, and it was alleged to have flown a distance +of one hundred and sixty-four feet. Whatever truth there may be +in the allegation, the machine was wrecked through deficient +equilibrium at the end of the trial. Ader repeated the +construction, and on October 14th, 1897, tried out his third +machine at the military establishment at Satory in the presence +of the French military authorities, on a circular track +specially prepared for the experiment. Ader and his friends +alleged that a flight of nearly a thousand feet was made; again +the machine was wrecked at the end of the trial, and there +Ader's practical work may be said to have ended, since no more +funds were forthcoming for the subsidy of experiments. + +There is the bald narrative, but it is worthy of some +amplification. If Ader actually did what he claimed, then the +position which the Wright Brothers hold as first to navigate the +air in a power-driven plane is nullified. Although at this time +of writing it is not a quarter of a century since Ader's +experiment in the presence of witnesses competent to judge on +his accomplishment, there is no proof either way, and whether he +was or was not the first man to fly remains a mystery in the +story of the conquest of the air. + +The full story of Ader's work reveals a persistence and +determination to solve the problem that faced him which was +equal to that of Lilienthal. He began by penetrating into the +interior of Algeria after having disguised himself as an Arab, +and there he spent some months in studying flight as practiced +by the vultures of the district. Returning to France in 1886 he +began to construct the 'Eole,' modelling it, not on the vulture, +but in the shape of a bat. Like the Lilienthal and Pilcher +gliders this machine was fitted with wings which could be +folded; the first flight made, as already noted, on October 9th, +1890, took place in the grounds of the chateau d'Amainvilliers, +near Bretz; two fellow-enthusiasts named Espinosa and Vallier +stated that a flight was actually made; no statement in the +history of aeronautics has been subject of so much question, and +the claim remains unproved. + +It was in September of 1891 that Ader, by permission of the +Minister of War, moved the 'Eole' to the military establishment +at Satory for the purpose of further trial. By this time, +whether he had flown or not, his nineteen years of work in +connection with the problems attendant on mechanical flight had +attracted so much attention that henceforth his work was subject +to the approval of the military authorities, for already it was +recognised that an efficient flying machine would confer an +inestimable advantage on the power that possessed it in the +event of war. At Satory the 'Eole' was alleged to have made a +flight of 109 yards, or, according to another account, 164 feet, +as stated above, in the trial in which the machine wrecked +itself through colliding with some carts which had been placed +near the track--the root cause of this accident, however, was +given as deficient equilibrium. + +Whatever the sceptics may say, there is reason for belief in the +accomplishment of actual flight by Ader with his first machine +in the fact that, after the inevitable official delay of some +months, the French War Ministry granted funds for further +experiment. Ader named his second machine, which he began to +build in May, 1892, the 'Avion,' and--an honour which he well +deserve--that name remains in French aeronautics as descriptive +of the power-driven aeroplane up to this day. + +This second machine, however, was not a success, and it was not +until 1897 that the second 'Avion,' which was the third +power-driven aeroplane of Ader's construction, was ready for +trial. This was fitted with two steam motors of twenty +horse-power each, driving two four-bladed propellers; the wings +warped automatically: that is to say, if it were necessary to +raise the trailing edge of one wing on the turn, the trailing +edge of the opposite wing was also lowered by the same movement; +an under-carriage was also fitted, the machine running on three +small wheels, and levers controlled by the feet of the aviator +actuated the movement of the tail planes. + +On October the 12th, 1897, the first trials of this 'Avion' were +made in the presence of General Mensier, who admitted that the +machine made several hops above the ground, but did not consider +the performance as one of actual flight. The result was so +encouraging, in spite of the partial failure, that, two days +later, General Mensier, accompanied by General Grillon, a +certain Lieutenant Binet, and two civilians named respectively +Sarrau and Leaute, attended for the purpose of giving the +machine an official trial, over which the great controversy +regarding Ader's success or otherwise may be said to have +arisen. + +We will take first Ader's own statement as set out in a very +competent account of his work published in Paris in 1910. Here +are Ader's own words: 'After some turns of the propellers, and +after travelling a few metres, we started off at a lively pace; +the pressure-gauge registered about seven atmospheres; almost +immediately the vibrations of the rear wheel ceased; a little +later we only experienced those of the front wheels at +intervals. 'Unhappily, the wind became suddenly strong, and we +had some difficulty in keeping the "Avion" on the white line. +We increased the pressure to between eight and nine atmospheres, +and immediately the speed increased considerably, and the +vibrations of the wheels were no longer sensible; we were at +that moment at the point marked G in the sketch; the "Avion" +then found itself freely supported by its wings; under the +impulse of the wind it continually tended to go outside the +(prepared) area to the right, in spite of the action of the +rudder. On reaching the point V it found itself in a very +critical position; the wind blew strongly and across the +direction of the white line which it ought to follow; the +machine then, although still going forward, drifted quickly out +of the area; we immediately put over the rudder to the left as +far as it would go; at the same time increasing the pressure +still more, in order to try to regain the course. The "Avion" +obeyed, recovered a little, and remained for some seconds headed +towards its intended course, but it could not struggle against +the wind; instead of going back, on the contrary it drifted +farther and farther away. And ill-luck had it that the drift +took the direction towards part of the School of Musketry, which +was guarded by posts and barriers. Frightened at the prospect +of breaking ourselves against these obstacles, surprised at +seeing the earth getting farther away from under the "Avion," +and very much impressed by seeing it rushing sideways at a +sickening speed, instinctively we stopped everything. What +passed through our thoughts at this moment which threatened a +tragic turn would be difficult to set down. All at once came a +great shock, splintering, a heavy concussion: we had landed.' + +Thus speaks the inventor; the cold official mind gives out a +different account, crediting the 'Avion' with merely a few hops, +and to-day, among those who consider the problem at all, there +is a little group which persists in asserting that to Ader +belongs the credit of the first power-driven flight, while a +larger group is equally persistent in stating that, save for a +few ineffectual hops, all three wheels of the machine never left +the ground. It is past question that the 'Avion' was capable of +power-driven flight; whether it achieved it or no remains an +unsettled problem. + +Ader's work is negative proof of the value of such experiments +as Lilienthal, Pilcher, Chanute, and Montgomery conducted; these +four set to work to master the eccentricities of the air before +attempting to use it as a supporting medium for continuous +flight under power; Ader attacked the problem from the other +end; like many other experimenters he regarded the air as a +stable fluid capable of giving such support to his machine as +still water might give to a fish, and he reckoned that he had +only to produce the machine in order to achieve flight. The +wrecked 'Avion' and the refusal of the French War Ministry to +grant any more funds for further experiment are sufficient +evidence of the need for working along the lines taken by the +pioneers of gliding rather than on those which Ader himself +adopted. + +Let it not be thought that in this comment there is any desire +to derogate from the position which Ader should occupy in any +study of the pioneers of aeronautical enterprise. If he failed, +he failed magnificently, and if he succeeded, then the student +of aeronautics does him an injustice and confers on the Brothers +Wright an honour which, in spite of the value of their work, +they do not deserve. There was one earlier than Ader, Alphonse +Penaud, who, in the face of a lesser disappointment than that +which Ader must have felt in gazing on the wreckage of his +machine, committed suicide; Ader himself, rendered unable to do +more, remained content with his achievement, and with the +knowledge that he had played a good part in the long search +which must eventually end in triumph. Whatever the world might +say, he himself was certain that he had achieved flight. This, +for him, was perforce enough. + +Before turning to consideration of the work accomplished by the +Brothers Wright, and their proved conquest of the air, it is +necessary first to sketch as briefly as may be the experimental +work of Sir (then Mr) Hiram Maxim, who, in his book, Artificial +and Natural Flight, has given a fairly complete account of his +various experiments. He began by experimenting with models, +with screw-propelled planes so attached to a horizontal movable +arm that when the screw was set in motion the plane described a +circle round a central point, and, eventually, he built a giant +aeroplane having a total supporting area of 1,500 square feet, +and a wing-span of fifty feet. It has been thought advisable to +give a fairly full description of the power plant used to the +propulsion of this machine in the section devoted to engine +development. The aeroplane, as Maxim describes it, had five +long and narrow planes projecting from each side, and a main or +central plane of pterygoid aspect. A fore and aft rudder was +provided, and had all the auxiliary planes been put in position +for experimental work a total lifting surface of 6,000 square +feet could have been obtained. Maxim, however, did not use more +than 4,000 square feet of lifting surface even in his later +experiments; with this he judged the machine capable of lifting +slightly under 8,000 lbs. weight, made up of 600 lbs. water in +the boiler and tank, a crew of three men, a supply of naphtha +fuel, and the weight of the machine itself. + +Maxim's intention was, before attempting free flight, to get as +much data as possible regarding the conditions under which +flight must be obtained, by what is known in these days as +'taxi-ing'--that is, running the propellers at sufficient speed +to drive the machine along the ground without actually mounting +into the air. He knew that he had an immense lifting surface +and a tremendous amount of power in his engine even when the +total weight of the experimental plant was taken into +consideration, and thus he set about to devise some means of +keeping the machine on the nine foot gauge rail track which had +been constructed for the trials. At the outset he had a set of +very heavy cast-iron wheels made on which to mount the machine, +the total weight of wheels, axles, and connections being about +one and a half tons. These were so constructed that the light +flanged wheels which supported the machine on the steel rails +could be lifted six inches above the track, still leaving the +heavy wheels on the rails for guidance of the machine. 'This +arrangement,' Maxim states, 'was tried on several occasions, the +machine being run fast enough to lift the forward end off the +track. However, I found considerable difficulty in starting and +stopping quickly on account of the great weight, and the amount +of energy necessary to set such heavy wheels spinning at a high +velocity. The last experiment with these wheels was made when a +head wind was blowing at the rate of about ten miles an hour. +It was rather unsteady, and when the machine was running at its +greatest velocity, a sudden gust lifted not only the front end, +but also the heavy front wheels completely off the track, and +the machine falling on soft ground was soon blown over by the +wind.' + +Consequently, a safety track was provided, consisting of squared +pine logs, three inches by nine inches, placed about two feet +above the steel way and having a thirty-foot gauge. Four extra +wheels were fitted to the machine on outriggers and so adjusted +that, if the machine should lift one inch clear of the steel +rails, the wheels at the ends of the outriggers would engage the +under side of the pine trackway. + +The first fully loaded run was made in a dead calm with 150 lbs. +steam pressure to the square inch, and there was no sign of the +wheels leaving the steel track. On a second run, with 230 lbs. +steam pressure the machine seemed to alternate between adherence +to the lower and upper tracks, as many as three of the outrigger +wheels engaging at the same time, and the weight on the steel +rails being reduced practically to nothing. In preparation for +a third run, in which it was intended to use full power, a +dynamometer was attached to the machine and the engines were +started at 200 lbs. pressure, which was gradually increased to +310 lbs per square inch. The incline of the track, added to the +reading of the dynamometer, showed a total screw thrust of 2,164 +lbs. After the dynamometer test had been completed, and +everything had been made ready for trial in motion, careful +observers were stationed on each side of the track, and the +order was given to release the machine. What follows is best +told in Maxim's own words:-- + +'The enormous screw-thrust started the engine so quickly that it +nearly threw the engineers off their feet, and the machine +bounded over the track at a great rate. Upon noticing a slight +diminution in the steam pressure, I turned on more gas, when +almost instantly the steam commenced to blow a steady blast from +the small safety valve, showing that the pressure was at least +320 lbs. in the pipes supplying the engines with steam. Before +starting on this run, the wheels that were to engage the upper +track were painted, and it was the duty of one of my assistants +to observe these wheels during the run, while another assistant +watched the pressure gauges and dynagraphs. The first part of +the track was up a slight incline, but the machine was lifted +clear of the lower rails and all of the top wheels were fully +engaged on the upper track when about 600 feet had been covered. +The speed rapidly increased, and when 900 feet had been covered, +one of the rear axle trees, which were of two-inch steel tubing, +doubled up and set the rear end of the machine completely free. +The pencils ran completely across the cylinders of the +dynagraphs and caught on the underneath end. The rear end of +the machine being set free, raised considerably above the track +and swayed. At about 1,000 feet, the left forward wheel also +got clear of the upper track, and shortly afterwards the right +forward wheel tore up about 100 feet of the upper track. Steam +was at once shut off and the machine sank directly to the earth, +embedding the wheels in the soft turf without leaving any other +marks, showing most conclusively that the machine was completely +suspended in the air before it settled to the earth. In this +accident, one of the pine timbers forming the upper track went +completely through the lower framework of the machine and broke +a number of the tubes, but no damage was done to the machinery +except a slight injury to one of the screws.' + +It is a pity that the multifarious directions in which Maxim +turned his energies did not include further development of the +aeroplane, for it seems fairly certain that he was as near +solution of the problem as Ader himself, and, but for the +holding-down outer track, which was really the cause of his +accident, his machine would certainly have achieved free flight, +though whether it would have risen, flown and alighted, without +accident, is matter for conjecture. + +The difference between experiments with models and with +full-sized machines is emphasised by Maxim's statement to the +effect that with a small apparatus for ascertaining the power +required for artificial flight, an angle of incidence of one in +fourteen was most advantageous, while with a large machine he +found it best to increase his angle to one in eight in order to +get the maximum lifting effect on a short run at a moderate +speed. He computed the total lifting effect in the experiments +which led to the accident as not less than 10,000 lbs., in which +is proof that only his rail system prevented free flight. + + + +X. SAMUEL PIERPOINT LANGLEY + +Langley was an old man when he began the study of aeronautics, +or, as he himself might have expressed it, the study of +aerodromics, since he persisted in calling the series of +machines he built 'Aerodromes,' a word now used only to denote +areas devoted to use as landing spaces for flying machines; the +Wright Brothers, on the other hand, had the great gift of youth +to aid them in their work. Even so it was a great race between +Langley, aided by Charles Manly, and Wilbur and Orville Wright, +and only the persistent ill-luck which dogged Langley from the +start to the finish of his experiments gave victory to his +rivals. It has been proved conclusively in these later years of +accomplished flight that the machine which Langley launched on +the Potomac River in October of 1903 was fully capable of +sustained flight, and only the accidents incurred in launching +prevented its pilot from being the first man to navigate the air +successfully in a power-driven machine. + +The best account of Langley's work is that diffused throughout a +weighty tome issued by the Smithsonian Institution, entitled the +Langley Memoir on Mechanical Flight, of which about one-third +was written by Langley himself, the remainder being compiled by +Charles M. Manly, the engineer responsible for the construction +of the first radial aero-engine, and chief assistant to Langley +in his experiments. To give a twentieth of the contents of this +volume in the present short account of the development of +mechanical flight would far exceed the amount of space that can +be devoted even to so eminent a man in aeronautics as S. P. +Langley, who, apart from his achievement in the construction of +a power-driven aeroplane really capable of flight, was a +scientist of no mean order, and who brought to the study of +aeronautics the skill of the trained investigator allied to the +inventive resource of the genius. + +That genius exemplified the antique saw regarding the infinite +capacity for taking pains, for the Langley Memoir shows that as +early as 1891 Langley had completed a set of experiments, +lasting through years, which proved it possible to construct +machines giving such a velocity to inclined surfaces that bodies +indefinitely heavier than air could be sustained upon it and +propelled through it at high speed. For full account (very +full) of these experiments, and of a later series leading up to +the construction of a series of 'model aerodromes' capable of +flight under power, it is necessary to turn to the bulky memoir +of Smithsonian origin. + +The account of these experiments as given by Langley himself +reveals the humility of the true investigator. Concerning them, +Langley remarks that, 'Everything here has been done with a view +to putting a trial aerodrome successfully in flight within a few +years, and thus giving an early demonstration of the only kind +which is conclusive in the eyes of the scientific man, as well +as of the general public--a demonstration that mechanical flight +is possible--by actually flying. All that has been done has +been with an eye principally to this immediate result, and all +the experiments given in this book are to be considered only as +approximations to exact truth. All were made with a view, not +to some remote future, but to an arrival within the compass of a +few years at some result in actual flight that could not be +gainsaid or mistaken.' + +With a series of over thirty rubber-driven models Langley +demonstrated the practicability of opposing curved surfaces to +the resistance of the air in such a way as to achieve flight, in +the early nineties of last century; he then set about finding +the motive power which should permit of the construction of +larger machines, up to man-carrying size. The internal +combustion engine was then an unknown quantity, and he had to +turn to steam, finally, as the propulsive energy for his power +plant. The chief problem which faced him was that of the +relative weight and power of his engine; he harked back to the +Stringfellow engine of 1868, which in 1889 came into the +possession of the Smithsonian Institution as a historical +curiosity. Rightly or wrongly Langley concluded on examination +that this engine never had developed and never could develop +more than a tenth of the power attributed to it; consequently he +abandoned the idea of copying the Stringfellow design and set +about making his own engine. + +How he overcame the various difficulties that faced him and +constructed a steam-engine capable of the task allotted to it +forms a story in itself, too long for recital here. His first +power-driven aerodrome of model size was begun in November of +1891, the scale of construction being decided with the idea that +it should be large enough to carry an automatic steering +apparatus which would render the machine capable of maintaining +a long and steady flight. The actual weight of the first model +far exceeded the theoretical estimate, and Langley found that a +constant increase of weight under the exigencies of construction +was a feature which could never be altogether eliminated. The +machine was made principally of steel, the sustaining surfaces +being composed of silk stretched from a steel tube with wooden +attachments. The first engines were the oscillating type, but +were found deficient in power. This led to the construction of +single-acting inverted oscillating engines with high and low +pressure cylinders, and with admission and exhaust ports to +avoid the complication and weight of eccentric and valves. +Boiler and furnace had to be specially designed; an analysis of +sustaining surfaces and the settlement of equilibrium while in +flight had to be overcome, and then it was possible to set about +the construction of the series of model aerodromes and make test +of their 'lift.' + +By the time Langley had advanced sufficiently far to consider it +possible to conduct experiments in the open air, even with these +models, he had got to his fifth aerodrome, and to the year 1894. +Certain tests resulted in failure, which in turn resulted in +further modifications of design, mainly of the engines. By +February of 1895 Langley reported that under favourable +conditions a lift of nearly sixty per cent of the flying weight +was secured, but although this was much more than was required +for flight, it was decided to postpone trials until two machines +were ready for the test. May, 1896, came before actual trials +were made, when one machine proved successful and another, a +later design, failed. The difficulty with these models was that +of securing a correct angle for launching; Langley records how, +on launching one machine, it rose so rapidly that it attained an +angle of sixty degrees and then did a tail slide into the water +with its engines working at full speed, after advancing nearly +forty feet and remaining in the air for about three seconds. +Here, Langley found that he had to obtain greater rigidity in +his wings, owing to the distortion of the form of wing under +pressure, and how he overcame this difficulty constitutes yet +another story too long for the telling here. + +Field trials were first attempted in 1893, and Langley blamed +his launching apparatus for their total failure. There was a +brief, but at the same time practical, success in model flight +in 1894, extending to between six and seven seconds, but this +only proved the need for strengthening of the wing. In 1895 +there was practically no advance toward the solution of the +problem, but the flights of May 6th and November 28th, 1896, +were notably successful. A diagram given in Langley's memoir +shows the track covered by the aerodrome on these two flights; +in the first of them the machine made three complete circles, +covering a distance of 3,200 feet; in the second, that of +November 28th, the distance covered was 4,200 feet, or about +three-quarters of a mile, at a speed of about thirty miles an +hour. + +These achievements meant a good deal; they proved mechanically +propelled flight possible. The difference between them and such +experiments as were conducted by Clement Ader, Maxim, and +others, lay principally in the fact that these latter either did +or did not succeed in rising into the air once, and then, either +willingly or by compulsion, gave up the quest, while Langley +repeated his experiments and thus attained to actual proof of +the possibilities of flight. Like these others, however, he +decided in 1896 that he would not undertake the construction of +a large man-carrying machine. In addition to a multitude of +actual duties, which left him practically no time available for +original research, he had as an adverse factor fully ten years +of disheartening difficulties in connection with his model +machines. It was President McKinley who, by requesting Langley +to undertake the construction and test of a machine which might +finally lead to the development of a flying machine capable of +being used in warfare, egged him on to his final experiment. +Langley's acceptance of the offer to construct such a machine is +contained in a letter addressed from the Smithsonian Institution +on December 12th, 1898, to the Board of Ordnance and +Fortification of the United States War Department; this letter +is of such interest as to render it worthy of reproduction:-- + +'Gentlemen,--In response to your invitation I repeat what I had +the honour to say to the Board--that I am willing, with the +consent of the Regents of this Institution, to undertake for the +Government the further investigation of the subject of the +construction of a flying machine on a scale capable of carrying +a man, the investigation to include the construction, +development and test of such a machine under conditions left as +far as practicable in my discretion, it being understood that my +services are given to the Government in such time as may not be +occupied by the business of the Institution, and without charge. + +'I have reason to believe that the cost of the construction will +come within the sum of $50,000.00, and that not more than +one-half of that will be called for in the coming year. + +'I entirely agree with what I understand to be the wish of the +Board that privacy be observed with regard to the work, and only +when it reaches a successful completion shall I wish to make +public the fact of its success. + +'I attach to this a memorandum of my understanding of some +points of detail in order to be sure that it is also the +understanding of the Board, and I am, gentlemen, with much +respect, your obedient servant, S. P. Langley.' + +One of the chief problems in connection with the construction of +a full-sized apparatus was that of the construction of an +engine, for it was realised from the first that a steam power +plant for a full-sized machine could only be constructed in such +a way as to make it a constant menace to the machine which it +was to propel. By this time (1898) the internal combustion +engine had so far advanced as to convince Langley that it formed +the best power plant available. A contract was made for the +delivery of a twelve horse-power engine to weigh not more than a +hundred pounds, but this contract was never completed, and it +fell to Charles M. Manly to design the five-cylinder radial +engine, of which a brief account is included in the section of +this work devoted to aero engines, as the power plant for the +Langley machine. + +The history of the years 1899 to 1903 in the Langley series of +experiments contains a multitude of detail far beyond the scope +of this present study, and of interest mainly to the designer. +There were frames, engines, and propellers, to be considered, +worked out, and constructed. We are concerned here mainly with +the completed machine and its trials. Of these latter it must +be remarked that the only two actual field trials which took +place resulted in accidents due to the failure of the launching +apparatus, and not due to any inherent defect in the machine. +It was intended that these two trials should be the first of a +series, but the unfortunate accidents, and the fact that no +further funds were forthcoming for continuance of experiments, +prevented Langley's success, which, had he been free to go +through as he intended with his work, would have been certain. + +The best brief description of the Langley aerodrome in its final +form, and of the two attempted trials, is contained in the +official report of Major M. M. Macomb of the United States +Artillery Corps, which report is here given in full:-- + + REPORT + +Experiments with working models which were concluded August 8 +last having proved the principles and calculations on which the +design of the Langley aerodrome was based to be correct, the +next step was to apply these principles to the construction of a +machine of sufficient size and power to permit the carrying of a +man, who could control the motive power and guide its flight, +thus pointing the way to attaining the final goal of producing a +machine capable of such extensive and precise aerial flight, +under normal atmospheric conditions, as to prove of military or +commercial utility. + +Mr C. M. Manly, working under Professor Langley, had, by the +summer of 1903, succeeded in completing an engine-driven machine +which under favourable atmospheric conditions was expected to +carry a man for any time up to half an hour, and to be capable +of having its flight directed and controlled by him. + +The supporting surface of the wings was ample, and experiment +showed the engine capable of supplying more than the necessary +motive power. + +Owing to the necessity of lightness, the weight of the various +elements had to be kept at a minimum, and the factor of safety +in construction was therefore exceedingly small, so that the +machine as a whole was delicate and frail and incapable of +sustaining any unusual strain. This defect was to be corrected +in later models by utilising data gathered in future experiments +under varied conditions. + +One of the most remarkable results attained was the production +of a gasoline engine furnishing over fifty continuous +horse-power for a weight of 120 lbs. + +The aerodrome, as completed and prepared for test, is briefly +described by Professor Langley as 'built of steel, weighing +complete about 730 lbs., supported by 1,040 feet of sustaining +surface, having two propellers driven by a gas engine developing +continuously over fifty brake horse-power.' + +The appearance of the machine prepared for flight was +exceedingly light and graceful, giving an impression to all +observers of being capable of successful flight. + +On October 7 last everything was in readiness, and I witnessed +the attempted trial on that day at Widewater, Va. On the +Potomac. The engine worked well and the machine was launched at +about 12.15 p.m. The trial was unsuccessful because the front +guy-post caught in its support on the launching car and was not +released in time to give free flight, as was intended, but, on +the contrary, caused the front of the machine to be dragged +downward, bending the guy-post and making the machine plunge +into the water about fifty yards in front of the house-boat. +The machine was subsequently recovered and brought back to the +house-boat. The engine was uninjured and the frame only slightly +damaged, but the four wings and rudder were practically destroyed +by the first plunge and subsequent towing back to the house-boat. + +This accident necessitated the removal of the house-boat to +Washington for the more convenient repair of damages. + +On December 8 last, between 4 and 5 p.m., another attempt at a +trial was made, this time at the junction of the Anacostia with +the Potomac, just below Washington Barracks. + +On this occasion General Randolph and myself represented the +Board of Ordnance and Fortification. The launching car was +released at 4.45 p.m. being pointed up the Anacostia towards the +Navy Yard. My position was on the tug Bartholdi, about 150 feet +from and at right angles to the direction of proposed flight. +The car was set in motion and the propellers revolved rapidly, +the engine working perfectly, but there was something wrong with +the launching. The rear guy-post seemed to drag, bringing the +rudder down on the launching ways, and a crashing, rending +sound, followed by the collapse of the rear wings, showed that +the machine had been wrecked in the launching, just how, it was +impossible for me to see. The fact remains that the rear wings +and rudder were wrecked before the machine was free of the ways. +Their collapse deprived the machine of its support in the rear, +and it consequently reared up in front under the action of the +motor, assumed a vertical position, and then toppled over to the +rear, falling into the water a few feet in front of the boat. + +Mr Manly was pulled out of the wreck uninjured and the wrecked +machine--was subsequently placed upon the house-boat, and the +whole brought back to Washington. + +From what has been said it will be seen that these unfortunate +accidents have prevented any test of the apparatus in free +flight, and the claim that an engine-driven, man-carrying +aerodrome has been constructed lacks the proof which actual +flight alone can give. + +Having reached the present stage of advancement in its +development, it would seem highly desirable, before laying down +the investigation, to obtain conclusive proof of the possibility +of free flight, not only because there are excellent reasons to +hope for success, but because it marks the end of a definite +step toward the attainment of the final goal. + +Just what further procedure is necessary to secure successful +flight with the large aerodrome has not yet been decided upon. +Professor Langley is understood to have this subject under +advisement, and will doubtless inform the Board of his final +conclusions as soon as practicable. + +In the meantime, to avoid any possible misunderstanding, it +should be stated that even after a successful test of the +present great aerodrome, designed to carry a man, we are still +far from the ultimate goal, and it would seem as if years of +constant work and study by experts, together with the +expenditure of thousands of dollars, would still be necessary +before we can hope to produce an apparatus of practical utility +on these lines.--Washington, January 6, 1904. + +A subsequent report of the Board of ordnance and Fortification +to the Secretary of War embodied the principal points in Major +Macomb's report, but as early as March 3rd, 1904, the Board came +to a similar conclusion to that of the French Ministry of War in +respect of Clement Ader's work, stating that it was not +'prepared to make an additional allotment at this time for +continuing the work.' This decision was in no small measure due +to hostile newspaper criticisms. Langley, in a letter to the +press explaining his attitude, stated that he did not wish to +make public the results of his work till these were certain, in +consequence of which he refused admittance to newspaper +representatives, and this attitude produced a hostility which +had effect on the United States Congress. An offer was made to +commercialise the invention, but Langley steadfastly refused it. +Concerning this, Manly remarks that Langley had 'given his time +and his best labours to the world without hope of remuneration, +and he could not bring himself, at his stage of life, to consent +to capitalise his scientific work.' + +The final trial of the Langley aerodrome was made on December +8th, 1903; nine days later, on December 17th, the Wright +Brothers made their first flight in a power-propelled machine, +and the conquest of the air was thus achieved. But for the two +accidents that spoilt his trials, the honour which fell to the +Wright Brothers would, beyond doubt, have been secured by Samuel +Pierpoint Langley. + + + +XI. THE WRIGHT BROTHERS + +Such information as is given here concerning the Wright Brothers +is derived from the two best sources available, namely, the +writings of Wilbur Wright himself, and a lecture given by Dr +Griffith Brewer to members of the Royal Aeronautical Society. +There is no doubt that so far as actual work in connection with +aviation accomplished by the two brothers is concerned, Wilbur +Wright's own statements are the clearest and best available. +Apparently Wilbur was, from the beginning, the historian of the +pair, though he himself would have been the last to attempt to +detract in any way from the fame that his brother's work also +deserves. Throughout all their experiments the two were +inseparable, and their work is one indivisible whole; in fact, +in every department of that work, it is impossible to say where +Orville leaves off and where Wilbur begins. + +It is a great story, this of the Wright Brothers, and one worth +all the detail that can be spared it. It begins on the 16th +April, 1867, when Wilbur Wright was born within eight miles of +Newcastle, Indiana. Before Orville's birth on the 19th August, +1871, the Wright family had moved to Dayton, Ohio, and settled +on what is known as the 'West Side' of the town. Here the +brothers grew up, and, when Orville was still a boy in his +teens, he started a printing business, which, as Griffith +Brewer remarks, was only limited by the smallness of his machine +and small quantity of type at his disposal. This machine was in +such a state that pieces of string and wood were incorporated in +it by way of repair, but on it Orville managed to print a boys' +paper which gained considerable popularity in Dayton 'West +Side.' Later, at the age of seventeen, he obtained a more +efficient outfit, with which he launched a weekly newspaper, +four pages in size, entitled The West Side News. After three +months' running the paper was increased in size and Wilbur came +into the enterprise as editor, Orville remaining publisher. In +1894 the two brothers began the publication of a weekly +magazine, Snap-Shots, to which Wilbur contributed a series of +articles on local affairs that gave evidence of the incisive and +often sarcastic manner in which he was able to express himself +throughout his life. Dr Griffith Brewer describes him as a +fearless critic, who wrote on matters of local interest in a +kindly but vigorous manner, which did much to maintain the +healthy public municipal life of Dayton. + +Editorial and publishing enterprise was succeeded by the +formation, just across the road from the printing works, of the +Wright Cycle Company, where the two brothers launched out as +cycle manufacturers with the 'Van Cleve' bicycle, a machine of +great local repute for excellence of construction, and one which +won for itself a reputation that lasted long after it had ceased +to be manufactured. The name of the machine was that of an +ancestor of the brothers, Catherine Van Cleve, who was one of +the first settlers at Dayton, landing there from the River Miami +on April 1st, 1796, when the country was virgin forest. + +It was not until 1896 that the mechanical genius which +characterised the two brothers was turned to the consideration +of aeronautics. In that year they took up the problem +thoroughly, studying all the aeronautical information then in +print. Lilienthal's writings formed one basis for their +studies, and the work of Langley assisted in establishing in +them a confidence in the possibility of a solution to the +problems of mechanical flight. In 1909, at the banquet given by +the Royal Aero Club to the Wright Brothers on their return to +America, after the series of demonstration flights carried out +by Wilbur Wright on the Continent, Wilbur paid tribute to the +great pioneer work of Stringfellow, whose studies and +achievements influenced his own and Orville's early work. He +pointed out how Stringfellow devised an aeroplane having two +propellers and vertical and horizontal steering, and gave due +place to this early pioneer of mechanical flight. + +Neither of the brothers was content with mere study of the work +of others. They collected all the theory available in the books +published up to that time, and then built man-carrying gliders +with which to test the data of Lilienthal and such other +authorities as they had consulted. For two years they conducted +outdoor experiments in order to test the truth or otherwise of +what were enunciated as the principles of flight; after this +they turned to laboratory experiments, constructing a wind +tunnel in which they made thousands of tests with models of +various forms of curved planes. From their experiments they +tabulated thousands of readings, which Griffith Brewer remarks +as giving results equally efficient with those of the elaborate +tables prepared by learned institutions. + +Wilbur Wright has set down the beginnings of the practical +experiments made by the two brothers very clearly. 'The +difficulties,' he says, 'which obstruct the pathway to success +in flying machine construction are of three general classes: +(1) Those which relate to the construction of the sustaining +wings; (2) those which relate to the generation and application +of the power required to drive the machine through the air; (3) +those relating to the balancing and steering of the machine +after it is actually in flight. Of these difficulties two are +already to a certain extent solved. Men already know how to +construct wings, or aeroplanes, which, when driven through the +air at sufficient speed, will not only sustain the weight of the +wings themselves, but also that of the engine and the engineer +as well. Men also know how to build engines and' screws of +sufficient lightness and power to drive these planes at +sustaining speed. Inability to balance and steer still +confronts students of the flying problem, although nearly ten +years have passed (since Lilienthal's success). When this one +feature has been worked out, the age of flying machines will +have arrived, for all other difficulties are of minor +importance. + +'The person who merely watches the flight of a bird gathers the +impression that the bird has nothing to think of but the +flapping of its wings. As a matter of fact, this is a very +small part of its mental labour. Even to mention all the things +the bird must constantly keep in mind in order to fly securely +through the air would take a considerable time. If I take a +piece of paper and, after placing it parallel with the ground, +quickly let it fall, it will not settle steadily down as a +staid, sensible piece of paper ought to do, but it insists on +contravening every recognised rule of decorum, turning over and +darting hither and thither in the most erratic manner, much +after the style of an untrained horse. Yet this is the style of +steed that men must learn to manage before flying can become an +everyday sport. The bird has learned this art of equilibrium, +and learned it so thoroughly that its skill is not apparent to +our sight. We only learn to appreciate it when we can imitate +it. + +'Now, there are only two ways of learning to ride a fractious +horse: one is to get on him and learn by actual practice how +each motion and trick may be best met; the other is to sit on a +fence and watch the beast awhile, and then retire to the house +and at leisure figure out the best way of overcoming his jumps +and kicks. The latter system is the safer, but the former, on +the whole, turns out the larger proportion of good riders. It +is very much the same in learning to ride a flying machine; if +you are looking for perfect safety you will do well to sit on a +fence and watch the birds, but if you really wish to learn you +must mount a machine and become acquainted with its tricks by +actual trial. The balancing of a gliding or flying machine is +very simple in theory. It merely consists in causing the centre +of pressure to coincide with the centre of gravity.' + +These comments are taken from a lecture delivered by Wilbur +Wright before the Western Society of Engineers in September of +1901, under the presidency of Octave Chanute. In that lecture +Wilbur detailed the way in which he and his brother came to +interest themselves in aeronautical problems and constructed +their first glider. He speaks of his own notice of the death of +Lilienthal in 1896, and of the way in which this fatality roused +him to an active interest in aeronautical problems, which was +stimulated by reading Professor Marey's Animal Mechanism, not +for the first time. 'From this I was led to read more modern +works, and as my brother soon became equally interested with +myself, we soon passed from the reading to the thinking, and +finally to the working stage. It seemed to us that the main +reason why the problem had remained so long unsolved was that no +one had been able to obtain any adequate practice. We figured +that Lilienthal in five years of time had spent only about five +hours in actual gliding through the air. The wonder was not +that he had done so little, but that he had accomplished so +much. It would not be considered at all safe for a bicycle +rider to attempt to ride through a crowded city street after +only five hours' practice, spread out in bits of ten seconds +each over a period of five years; yet Lilienthal with this brief +practice was remarkably successful in meeting the fluctuations +and eddies of wind-gusts. We thought that if some method could +be found by which it would be possible to practice by the hour +instead of by the second there would be hope of advancing the +solution of a very difficult problem. It seemed feasible to do +this by building a machine which would be sustained at a speed +of eighteen miles per hour, and then finding a locality where +winds of this velocity were common. With these conditions a +rope attached to the machine to keep it from floating backward +would answer very nearly the same purpose as a propeller driven +by a motor, and it would be possible to practice by the hour, +and without any serious danger, as it would not be necessary to +rise far from the ground, and the machine would not have any +forward motion at all. We found, according to the accepted +tables of air pressure on curved surfaces, that a machine +spreading 200 square feet of wing surface would be sufficient +for our purpose, and that places would easily be found along the +Atlantic coast where winds of sixteen to twenty-five miles were +not at all uncommon. When the winds were low it was our plan to +glide from the tops of sandhills, and when they were +sufficiently strong to use a rope for our motor and fly over one +spot. Our next work was to draw up the plans for a suitable +machine. After much study we finally concluded that tails were +a source of trouble rather than of assistance, and therefore we +decided to dispense with them altogether. It seemed reasonable +that if the body of the operator could be placed in a horizontal +position instead of the upright, as in the machines of +Lilienthal, Pilcher, and Chanute, the wind resistance could be +very materially reduced, since only one square foot instead of +five would be exposed. As a full half horse-power would be +saved by this change, we arranged to try at least the horizontal +position. Then the method of control used by Lilienthal, which +consisted in shifting the body, did not seem quite as quick or +effective as the case required; so, after long study, we +contrived a system consisting of two large surfaces on the +Chanute double-deck plan, and a smaller surface placed a short +distance in front of the main surfaces in such a position that +the action of the wind upon it would counterbalance the effect +of the travel of the centre of pressure on the main surfaces. +Thus changes in the direction and velocity of the wind would +have little disturbing effect, and the operator would be +required to attend only to the steering of the machine, which +was to be effected by curving the forward surface up or down. +The lateral equilibrium and the steering to right or left was to +be attained by a peculiar torsion of the main surfaces which was +equivalent to presenting one end of the wings at a greater angle +than the other. In the main frame a few changes were also made +in the details of construction and trussing employed by Mr +Chanute. The most important of these were: (1) The moving of +the forward main crosspiece of the frame to the extreme front +edge; (2) the encasing in the cloth of all crosspieces and ribs +of the surfaces; (3) a rearrangement of the wires used in +trussing the two surfaces together, which rendered it possible +to tighten all the wires by simply shortening two of them.' + +The brothers intended originally to get 200 square feet of +supporting surface for their glider, but the impossibility of +obtaining suitable material compelled them to reduce the area to +165 square feet, which, by the Lilienthal tables, admitted of +support in a wind of about twenty-one miles an hour at an angle +of three degrees. With this glider they went in the summer of I +1900 to the little settlement of Kitty Hawk, North Carolina, +situated on the strip of land dividing Albemarle Sound from the +Atlantic. Here they reckoned on obtaining steady wind, and +here, on the day that they completed the machine, they took it +out for trial as a kite with the wind blowing at between +twenty-five and thirty miles an hour. They found that in order +to support a man on it the glider required an angle nearer +twenty degrees than three, and even with the wind at thirty +miles an hour they could not get down to the planned angle of +three degrees. 'Later, when the wind was too light to support +the machine with a man on it, they tested it as a kite, working +the rudders by cords. Although they obtained satisfactory +results in this way they realised fully that actual gliding +experience was necessary before the tests could be considered +practical. + +A series of actual measurements of lift and drift of the machine +gave astonishing results. 'It appeared that the total +horizontal pull of the machine, while sustaining a weight of 52 +lbs., was only 8.5 lbs., which was less than had been previously +estimated for head resistance of the framing alone. Making +allowance for the weight carried, it appeared that the head +resistance of the framing was but little more than fifty per +cent of the amount which Mr Chanute had estimated as the head +resistance of the framing of his machine. On the other hand, it +appeared sadly deficient in lifting power as compared with the +calculated lift of curved surfaces of its size... we decided to +arrange our machine for the following year so that the depth of +curvature of its surfaces could be varied at will, and its +covering air-proofed.' + +After these experiments the brothers decided to turn to +practical gliding, for which they moved four miles to the south, +to the Kill Devil sandhills, the principal of which is slightly +over a hundred feet in height, with an inclination of nearly ten +degrees on its main north-western slope. On the day after their +arrival they made about a dozen glides, in which, although the +landings were made at a speed of more than twenty miles an hour, +no injury was sustained either by the machine or by the +operator. + +'The slope of the hill was 9.5 degrees, or a drop of one foot in +six. We found that after attaining a speed of about twenty-five +to thirty miles with reference to the wind, or ten to fifteen +miles over the ground, the machine not only glided parallel to +the slope of the hill, but greatly increased its speed, thus +indicating its ability to glide on a somewhat less angle than +9.5 degrees, when we should feel it safe to rise higher from the +surface. The control of the machine proved even better than we +had dared to expect, responding quickly to the slightest motion +of the rudder. With these glides our experiments for the year +1900 closed. Although the hours and hours of practice we had +hoped to obtain finally dwindled down to about two minutes, we +were very much pleased with the general results of the trip, +for, setting out as we did with almost revolutionary theories on +many points and an entirely untried form of machine, we +considered it quite a point to be able to return without having +our pet theories completely knocked on the head by the hard +logic of experience, and our own brains dashed out in the +bargain. Everything seemed to us to confirm the correctness of +our original opinions: (1) That practice is the key to the +secret of flying; (2) that it is practicable to assume the +horizontal position; (3) that a smaller surface set at a +negative angle in front of the main bearing surfaces, or wings, +will largely counteract the effect of the fore and aft travel of +the centre of pressure; (4) that steering up and down can be +attained with a rudder without moving the position of the +operator's body; (5) that twisting the wings so as to present +their ends to the wind at different angles is a more prompt and +efficient way of maintaining lateral equilibrium than shifting +the body of the operator.' + +For the gliding experiments of 1901 it was decided to retain the +form of the 1900 glider, but to increase the area to 308 square +feet, which, the brothers calculated, would support itself and +its operator in a wind of seventeen miles an hour with an angle +of incidence of three degrees. Camp was formed at Kitty Hawk in +the middle of July, and on July 27th the machine was completed +and tried for the first time in a wind of about fourteen miles +an hour. The first attempt resulted in landing after a glide of +only a few yards, indicating that the centre of gravity was too +far in front of the centre of pressure. By shifting his +position farther and farther back the operator finally achieved +an undulating flight of a little over 300 feet, but to obtain +this success he had to use full power of the rudder to prevent +both stalling and nose-diving. With the 1900 machine one-fourth +of the rudder action had been necessary for far better control. + +Practically all glides gave the same result, and in one the +machine rose higher and higher until it lost all headway. 'This +was the position from which Lilienthal had always found +difficulty in extricating himself, as his machine then, in spite +of his greatest exertions, manifested a tendency to dive +downward almost vertically and strike the ground head on with +frightful velocity. In this case a warning cry from the ground +caused the operator to turn the rudder to its full extent and +also to move his body slightly forward. The machine then +settled slowly to the ground, maintaining its horizontal +position almost perfectly, and landed without any injury at all. +This was very encouraging, as it showed that one of the very +greatest dangers in machines with horizontal tails had been +overcome by the use of the front rudder. Several glides later +the same experience was repeated with the same result. In the +latter case the machine had even commenced to move backward, but +was nevertheless brought safely to the ground in a horizontal +position. On the whole this day's experiments were encouraging, +for while the action of the rudder did not seem at all like that +of our 1900 machine, yet we had escaped without difficulty from +positions which had proved very dangerous to preceding +experimenters, and after less than one minute's actual practice +had made a glide of more than 300 feet, at an angle of descent +of ten degrees, and with a machine nearly twice as large as had +previously been considered safe. The trouble with its control, +which has been mentioned, we believed could be corrected when we +should have located its cause.' + +It was finally ascertained that the defect could be remedied by +trussing down the ribs of the whole machine so as to reduce the +depth of curvature. When this had been done gliding was +resumed, and after a few trials glides of 366 and 389 feet were +made with prompt response on the part of the machine, even to +small movements of the rudder. The rest of the story of the +gliding experiments of 1901 cannot be better told than in Wilbur +Wright's own words, as uttered by him in the lecture from which +the foregoing excerpts have been made. + +'The machine, with its new curvature, never failed to respond +promptly to even small movements of the rudder. The operator +could cause it to almost skim the ground, following the +undulations of its surface, or he could cause it to sail out +almost on a level with the starting point, and, passing high +above the foot of the hill, gradually settle down to the ground. +The wind on this day was blowing eleven to fourteen miles per +hour. The next day, the conditions being favourable, the +machine was again taken out for trial. This time the velocity +of the wind was eighteen to twenty-two miles per hour. At first +we felt some doubt as to the safety of attempting free flight in +so strong a wind, with a machine of over 300 square feet and a +practice of less than five minutes spent in actual flight. But +after several preliminary experiments we decided to try a glide. +The control of the machine seemed so good that we then felt no +apprehension in sailing boldly forth. And thereafter we made +glide after glide, sometimes following the ground closely and +sometimes sailing high in the air. Mr Chanute had his camera +with him and took pictures of some of these glides, several of +which are among those shown. + +'We made glides on subsequent days, whenever the conditions were +favourable. The highest wind thus experimented in was a little +over twelve metres per second--nearly twenty-seven miles per +hour. + +It had been our intention when building the machine to do the +larger part of the experimenting in the following manner:--When +the wind blew seventeen miles an hour, or more, we would attach +a rope to the machine and let it rise as a kite with the +operator upon it. When it should reach a proper height the +operator would cast off the rope and glide down to the ground +just as from the top of a hill. In this way we would be saved +the trouble of carrying the machine uphill after each glide, and +could make at least ten glides in the time required for one in +the other way. But when we came to try it, we found that a wind +of seventeen miles, as measured by Richards' anemometer, instead +of sustaining the machine with its operator, a total weight of +240 lbs., at an angle of incidence of three degrees, in reality +would not sustain the machine alone--100 lbs.--at this angle. +Its lifting capacity seemed scarcely one third of the calculated +amount. In order to make sure that this was not due to the +porosity of the cloth, we constructed two small experimental +surfaces of equal size, one of which was air-proofed and the +other left in its natural state; but we could detect no +difference in their lifting powers. For a time we were led to +suspect that the lift of curved surfaces very little exceeded +that of planes of the same size, but further investigation and +experiment led to the opinion that (1) the anemometer used by us +over-recorded the true velocity of the wind by nearly 15 per +cent; (2) that the well-known Smeaton co-efficient of .005 V +squared for the wind pressure at 90 degrees is probably too +great by at least 20 per cent; (3) that Lilienthal's estimate +that the pressure on a curved surface having an angle of +incidence of 3 degrees equals .545 of the pressure at go degrees +is too large, being nearly 50 per cent greater than very recent +experiments of our own with a pressure testing-machine indicate; +(4) that the superposition of the surfaces somewhat reduced the +lift per square foot, as compared with a single surface of equal +area. + +'In gliding experiments, however, the amount of lift is of less +relative importance than the ratio of lift to drift, as this +alone decides the angle of gliding descent. In a plane the +pressure is always perpendicular to the surface, and the ratio +of lift to drift is therefore the same as that of the cosine to +the sine of the angle of incidence. But in curved surfaces a +very remarkable situation is found. The pressure, instead of +being uniformly normal to the chord of the arc, is usually +inclined considerably in front of the perpendicular. The result +is that the lift is greater and the drift less than if the +pressure were normal. Lilienthal was the first to discover this +exceedingly important fact, which is fully set forth in his +book, Bird Flight the Basis of the Flying Art, but owing to some +errors in the methods he used in making measurements, question +was raised by other investigators not only as to the accuracy of +his figures, but even as to the existence of any tangential +force at all. Our experiments confirm the existence of this +force, though our measurements differ considerably from those of +Lilienthal. While at Kitty Hawk we spent much time in measuring +the horizontal pressure on our unloaded machine at various +angles of incidence. We found that at 13 degrees the horizontal +pressure was about 23 lbs. This included not only the drift +proper, or horizontal component of the pressure on the side of +the surface, but also the head resistance of the framing as +well. The weight of the machine at the time of this test was +about 108 lbs. Now, if the pressure had been normal to the +chord of the surface, the drift proper would have been to the +lift (108 lbs.) as the sine of 13 degrees is to the cosine of 13 +degrees, or .22 X 108/.97 = 24+ lbs.; but this slightly exceeds +the total pull of 23 pounds on our scales. Therefore it is +evident that the average pressure on the surface, instead of +being normal to the chord, was so far inclined toward the front +that all the head resistance of framing and wires used in the +construction was more than overcome. In a wind of fourteen +miles per hour resistance is by no means a negligible factor, so +that tangential is evidently a force of considerable value. In +a higher wind, which sustained the machine at an angle of 10 +degrees the pull on the scales was 18 lbs. With the pressure +normal to the chord the drift proper would have been 17 X 98/.98. +The travel of the centre of pressure made it necessary to put +sand on the front rudder to bring the centres of gravity and +pressure into coincidence, consequently the weight of the +machine varied from 98 lbs. to 108 lbs. in the different tests)= +17 lbs., so that, although the higher wind velocity must have +caused an increase in the head resistance, the tangential force +still came within 1 lb. of overcoming it. After our return +from Kitty Hawk we began a series of experiments to accurately +determine the amount and direction of the pressure produced on +curved surfaces when acted upon by winds at the various angles +from zero to 90 degrees. These experiments are not yet +concluded, but in general they support Lilienthal in the claim +that the curves give pressures more favourable in amount and +direction than planes; but we find marked differences in the +exact values, especially at angles below 10 degrees. We were +unable to obtain direct measurements of the horizontal pressures +of the machine with the operator on board, but by comparing the +distance travelled with the vertical fall, it was easily +calculated that at a speed of 24 miles per hour the total +horizontal resistances of our machine, when bearing the +operator, amounted to 40 lbs., which is equivalent to about +2 1/3 horse-power. It must not be supposed, however, that a +motor developing this power would be sufficient to drive a +man-bearing machine. The extra weight of the motor would +require either a larger machine, higher speed, or a greater +angle of incidence in order to support it, and therefore more +power. It is probable, however, that an engine of 6 +horse-power, weighing 100 lbs. would answer the purpose. Such +an engine is entirely practicable. Indeed, working motors of +one-half this weight per horse-power (9 lbs. per horse-power) +have been constructed by several different builders. Increasing +the speed of our machine from 24 to 33 miles per hour reduced +the total horizontal pressure from 40 to about 35 lbs. This was +quite an advantage in gliding, as it made it possible to sail +about 15 per cent farther with a given drop. However, it would +be of little or no advantage in reducing the size of the motor +in a power-driven machine, because the lessened thrust would be +counterbalanced by the increased speed per minute. Some years +ago Professor Langley called attention to the great economy of +thrust which might be obtained by using very high speeds, and +from this many were led to suppose that high speed was essential +to success in a motor-driven machine. But the economy to which +Professor Langley called attention was in foot pounds per mile +of travel, not in foot pounds per minute. It is the foot pounds +per minute that fixes the size of the motor. The probability is +that the first flying machines will have a relatively low speed, +perhaps not much exceeding 20 miles per hour, but the problem of +increasing the speed will be much simpler in some respects than +that of increasing the speed of a steamboat; for, whereas in the +latter case the size of the engine must increase as the cube of +the speed, in the flying machine, until extremely high speeds +are reached, the capacity of the motor increases in less than +simple ratio; and there is even a decrease in the fuel per mile +of travel. In other words, to double the speed of a steamship +(and the same is true of the balloon type of airship) eight +times the engine and boiler capacity would be required, and four +times the fuel consumption per mile of travel: while a flying +machine would require engines of less than double the size, and +there would be an actual decrease in the fuel consumption per +mile of travel. But looking at the matter conversely, the great +disadvantage of the flying machine is apparent; for in the +latter no flight at all is possible unless the proportion of +horse-power to flying capacity is very high; but on the other +hand a steamship is a mechanical success if its ratio of +horse-power to tonnage is insignificant. A flying machine that +would fly at a speed of 50 miles per hour with engines of 1,000 +horse-power would not be upheld by its wings at all at a speed +of less than 25 miles an hour, and nothing less than 500 +horse-power could drive it at this speed. But a boat which +could make 40 miles an hour with engines of 1,000 horse-power +would still move 4 miles an hour even if the engines were +reduced to 1 horse-power. The problems of land and water travel +were solved in the nineteenth century, because it was possible +to begin with small achievements, and gradually work up to our +present success. The flying problem was left over to the +twentieth century, because in this case the art must be highly +developed before any flight of any considerable duration at all +can be obtained. + +'However, there is another way of flying which requires no +artificial motor, and many workers believe that success will +come first by this road. I refer to the soaring flight, by +which the machine is permanently sustained in the air by the +same means that are employed by soaring birds. They spread +their wings to the wind, and sail by the hour, with no +perceptible exertion beyond that required to balance and steer +themselves. What sustains them is not definitely known, though +it is almost certain that it is a rising current of air. But +whether it be a rising current or something else, it is as well +able to support a flying machine as a bird, if man once learns +the art of utilising it. In gliding experiments it has long been +known that the rate of vertical descent is very much retarded, +and the duration of the flight greatly prolonged, if a strong +wind blows UP the face of the hill parallel to its surface. Our +machine, when gliding in still air, has a rate of vertical +descent of nearly 6 feet per second, while in a wind blowing 26 +miles per hour up a steep hill we made glides in which the rate +of descent was less than 2 feet per second. And during the larger +part of this time, while the machine remained exactly in the +rising current, THERE WAS NO DESCENT AT ALL, BUT EVEN A SLIGHT +RISE. If the operator had had sufficient skill to keep himself +from passing beyond the rising current he would have been +sustained indefinitely at a higher point than that from which he +started. The illustration shows one of these very slow glides at +a time when the machine was practically at a standstill. The +failure to advance more rapidly caused the photographer some +trouble in aiming, as you will perceive. In looking at this +picture you will readily understand that the excitement of +gliding experiments does not entirely cease with the breaking up +of camp. In the photographic dark-room at home we pass moments +of as thrilling interest as any in the field, when the image +begins to appear on the plate and it is yet an open question +whether we have a picture of a flying machine or merely a patch +of open sky. These slow glides in rising current probably hold +out greater hope of extensive practice than any other method +within man's reach, but they have the disadvantage of requiring +rather strong winds or very large supporting surfaces. However, +when gliding operators have attained greater skill, they can with +comparative safety maintain themselves in the air for hours at a +time in this way, and thus by constant practice so increase +their knowledge and skill that they can rise into the higher air +and search out the currents which enable the soaring birds to +transport themselves to any desired point by first rising in a +circle and then sailing off at a descending angle. This +illustration shows the machine, alone, flying in a wind of 35 +miles per hour on the face of a steep hill, 100 feet high. It +will be seen that the machine not only pulls upward, but also +pulls forward in the direction from which the wind blows, thus +overcoming both gravity and the speed of the wind. We tried the +same experiment with a man on it, but found danger that the +forward pull would become so strong, that the men holding the +ropes would be dragged from their insecure foothold on the slope +of the hill. So this form of experimenting was discontinued +after four or five minutes' trial. + +'In looking over our experiments of the past two years, with +models and full-size machines, the following points stand out +with clearness:-- + +'1. That the lifting power of a large machine, held stationary +in a wind at a small distance from the earth, is much less than +the Lilienthal table and our own laboratory experiments would +lead us to expect. When the machine is moved through the air, +as in gliding, the discrepancy seems much less marked. + +'2. That the ratio of drift to lift in well-shaped surfaces is +less at angles of incidence of 5 degrees to 12 degrees than at +an angle of 3 degrees. + +'3. That in arched surfaces the centre of pressure at 90 +degrees is near the centre of the surface, but moves slowly +forward as the angle becomes less, till a critical angle varying +with the shape and depth of the curve is reached, after which it +moves rapidly toward the rear till the angle of no lift is +found. + +'4. That with similar conditions large surfaces may be +controlled with not much greater difficulty than small ones, if +the control is effected by manipulation of the surfaces +themselves, rather than by a movement of the body of the +operator. + +'5. That the head resistances of the framing can be brought to +a point much below that usually estimated as necessary. + +'6. That tails, both vertical and horizontal, may with safety +be eliminated in gliding and other flying experiments. + +'7. That a horizontal position of the operator's body may be +assumed without excessive danger, and thus the head resistance +reduced to about one-fifth that of the upright position. + +'8. That a pair of superposed, or tandem surfaces, has less +lift in proportion to drift than either surface separately, even +after making allowance for weight and head resistance of the +connections.' + +Thus, to the end of the 1901 experiments, Wilbur Wright provided +a fairly full account of what was accomplished; the record shows +an amount of patient and painstaking work almost beyond +belief--it was no question of making a plane and launching it, +but a business of trial and error, investigation and tabulation +of detail, and the rejection time after time of previously +accepted theories, till the brothers must have felt the the +solid earth was no longer secure, at times. Though it was +Wilbur who set down this and other records of the work done, +yet the actual work was so much Orville's as his brother's that +no analysis could separate any set of experiments and say that +Orville did this and Wilbur that--the two were inseparable. On +this point Griffith Brewer remarked that 'in the arguments, if +one brother took one view, the other brother took the opposite +view as a matter of course, and the subject was thrashed to +pieces until a mutually acceptable result remained. I have +often been asked since these pioneer days, "Tell me, Brewer, who +was really the originator of those two?" In reply, I used +first to say, "I think it was mostly Wilbur," and later, +when I came to know Orville better, I said, "The thing could not +have been without Orville." Now, when asked, I have to say, " I +don't know," and I feel the more I think of it that it was only +the wonderful combination of these two brothers, who devoted +their lives together or this common object, that made the +discovery of the art of flying possible.' + +Beyond the 1901 experiments in gliding, the record grows more +scrappy, less detailed. It appears that once power-driven +flight had been achieved, the brothers were not so willing to +talk as before; considering the amount of work that they put in, +there could have been little time for verbal description +of that work--as already remarked, their tables still stand for +the designer and experimenter. The end of the 1901 experiments +left both brothers somewhat discouraged, though they had +accomplished more than any others. 'Having set out with +absolute faith in the existing scientific data, we ere driven to +doubt one thing after another, finally, after two years of +experiment, we cast it all aside, and decided to rely entirely +on our own investigations. Truth and error were everywhere so +in,timately mixed as to be indistinguishable.... We had taken up +aeronautics as a sport. We reluctantly entered upon the +scientific side of it.' + +Yet, driven thus to the more serious aspect of the work, they +found in the step its own reward, for the work of itself drew +them on and on, to the construction of measuring machines for +the avoidance of error, and to the making of series after series +of measurements, concerning which Wilbur wrote in 1908 (in the +Century Magazine) that 'after making preliminary measurements on +a great number of different shaped surfaces, to secure a general +understanding of the subject, we began systematic measurements +of standard surfaces, so varied in design as to bring out the +underlying causes of differences noted in their pressures. +Measurements were tabulated on nearly fifty of these at all +angles from zero to 45 degrees, at intervals of 2 1/2 degrees. +Measurements were also secured showing the effects on each other +when surfaces are superposed, or when they follow one another. + +'Some strange results were obtained. One surface, with a heavy +roll at the front edge, showed the same lift for all angles from +7 1/2 to 45 degrees. This seemed so anomalous that we were +almost ready to doubt our own measurements, when a simple test +was suggested. A weather vane, with two planes attached to the +pointer at an angle of 80 degrees with each other, was made. +According to our table, such a vane would be in unstable +equilibrium when pointing directly into the wind, for if by +chance the wind should happen to strike one plane at 39 degrees +and the other at 41 degrees, the plane with the smaller angle +would have the greater pressure and the pointer would be turned +still farther out of the course of the wind until the two vanes +again secured equal pressures, which would be at approximately +30 and 50 degrees. But the vane performed in this very manner. +Further corroboration of the tables was obtained in experiments +with the new glider at Kill Devil Hill the next season. + +'In September and October, 1902 nearly 1,000 gliding flights +were made, several of which covered distances of over 600 feet. +Some, made against a wind of 36 miles an hour, gave proof of the +effectiveness of the devices for control. With this machine, in +the autumn of 1903, we made a number of flights in which we +remained in the air for over a minute, often soaring for a +considerable time in one spot, without any descent at all. +Little wonder that our unscientific assistant should think the +only thing needed to keep it indefinitely in the air would be a +coat of feathers to make it light! ' + +It was at the conclusion of these experiments of 1903 that the +brothers concluded they had obtained sufficient data from their +thousands of glides and multitude of calculations to permit of +their constructing and making trial of a power-driven machine. +The first designs got out provided for a total weight of 600 +lbs., which was to include the weight of the motor and the +pilot; but on completion it was found that there was a surplus +of power from the motor, and thus they had 150 lbs. weight to +allow for strengthening wings and other parts. + +They came up against the problem to which Riach has since +devoted so much attention, that of propeller design. 'We had +thought of getting the theory of the screw-propeller from the +marine engineers, and then, by applying our table of +air-pressures to their formulae, of designing air-propellers +suitable for our uses. But, so far as we could learn, the +marine engineers possessed only empirical formulae, and the +exact action of the screw propeller, after a century of use, was +still very obscure. As we were not in a position to undertake a +long series of practical experiments to discover a propeller +suitable for our machine, it seemed necessary to obtain such a +thorough understanding of the theory of its reactions as would +enable us to design them from calculation alone. What at first +seemed a simple problem became more complex the longer we +studied it. With the machine moving forward, the air flying +backward, the propellers turning sidewise, and nothing standing +still, it seemed impossible to find a starting point from which +to trace the various simultaneous reactions. Contemplation of +it was confusing. After long arguments we often found ourselves +in the ludicrous position of each having been converted to the +other's side, with no more agreement than when the discussion +began. + +'It was not till several months had passed, and every phase of +the problem had been thrashed over and over, that the various +reactions began to untangle themselves. When once a clear +understanding had been obtained there was no difficulty in +designing a suitable propeller, with proper diameter, pitch, and +area of blade, to meet the requirements of the flier. High +efficiency in a screw-propeller is not dependent upon any +particular or peculiar shape, and there is no such thing as a +"best" screw. A propeller giving a high dynamic efficiency when +used upon one machine may be almost worthless when used upon +another. The propeller should in every case be designed to meet +the particular conditions of the machine to which it is to be +applied. Our first propellers, built entirely from calculation, +gave in useful work 66 per cent of the power expended. This was +about one-third more than had been secured by Maxim or Langley.' + +Langley had made his last attempt with the 'aerodrome,' and his +splendid failure but a few days before the brothers made their +first attempt at power-driven aeroplane flight. On December +17th, 1903, the machine was taken out; in addition to Wilbur and +Orville Wright, there were present five spectators: Mr A. D. +Etheridge, of the Kil1 Devil life-saving station; Mr W. S.Dough, +Mr W. C. Brinkley, of Manteo; Mr John Ward, of Naghead, and Mr +John T. Daniels.[*] A general invitation had been given to +practically all the residents in the vicinity, but the Kill +Devil district is a cold area in December, and history had +recorded so many experiments in which machines had failed to +leave the ground that between temperature and scepticism only +these five risked a waste of their time. + +[*] This list is as given by Wilbur Wright himself. + +And these five were in at the greatest conquest man had made +since James Watt evolved the steam engine --perhaps even a +greater conquest than that of Watt. Four flights in all were +made; the first lasted only twelve seconds, 'the first in the +history of the world in which a machine carrying a man had +raised itself into the air by its own power in free flight, had +sailed forward on a level course without reduction of speed, and +had finally landed without being wrecked,' said Wilbur +Wright concerning the achievement.[*] The next two flights were +slightly longer, and the fourth and last of the day was one +second short of the complete minute; it was made into the teeth +of a 20 mile an hour wind, and the distance travelled was 852 +feet. + +[*] Century Magazine, September, 1908. + +This bald statement of the day's doings is as Wilbur Wright +himself has given it, and there is in truth nothing more to say; +no amount of statement could add to the importance of the +achievement, and no more than the bare record is necessary. The +faith that had inspired the long roll of pioneers, from da Vinci +onward, was justified at last. + +Having made their conquest, the brothers took the machine back +to camp, and, as they thought, placed it in safety. Talking +with the little group of spectators about the flights, they +forgot about the machine, and then a sudden gust of wind struck +it. Seeing that it was being overturned, all made a rush toward +it to save it, and Mr Daniels, a man of large proportions, was +in some way lifted off his feet, falling between the planes. +The machine overturned fully, and Daniels was shaken like a die +in a cup as the wind rolled the machine over and over--he came +out at the end of his experience with a series of bad bruises, +and no more, but the damage done to the machine by the accident +was sufficient to render it useless for further experiment that +season. + +A new machine, stronger and heavier, was constructed by the +brothers, and in the spring of 1904 they began experiments again +at Sims Station, eight miles to the east of Dayton, their home +town. Press representatives were invited for the first trial, +and about a dozen came--the whole gathering did not number more +than fifty people. 'When preparations had been concluded,' +Wilbur Wright wrote of this trial, 'a wind of only three or four +miles an hour was blowing--insufficient for starting on so short +a track --but since many had come a long way to see the machine +in action, an attempt was made. To add to the other difficulty, +the engine refused to work properly. The machine, after running +the length of the track, slid off the end without rising into +the air at all. Several of the newspaper men returned next day +but were again disappointed. The engine performed badly, and +after a glide of only sixty feet the machine again came to the +ground. Further trial was postponed till the motor could be put +in better running condition. The reporters had now, no doubt, +lost confidence in the machine, though their reports, in +kindness, concealed it. Later, when they heard that we were +making flights of several minutes' duration, knowing that longer +flights had been made with airships, and not knowing any +essential difference between airships and flying machines, they +were but little interested. + +'We had not been flying long in 1904 before we found that the +problem of equilibrium had not as yet been entirely solved. +Sometimes, in making a circle, the machine would turn over +sidewise despite anything the operator could do, although, under +the same conditions in ordinary straight flight it could have +been righted in an instant. In one flight, in 1905, while +circling round a honey locust-tree at a height of about 50 feet, +the machine suddenly began to turn up on one wing, and took a +course toward the tree. The operator, not relishing the idea of +landing in a thorn tree, attempted to reach the ground. The +left wing, however, struck the tree at a height of 10 or 12 feet +from the ground and carried away several branches; but the +flight, which had already covered a distance of six miles, was +continued to the starting point. + +'The causes of these troubles--too technical for explanation +here--were not entirely overcome till the end of September, +1905. The flights then rapidly increased in length, till +experiments were discontinued after October 5 on account of the +number of people attracted to the field. Although made on a +ground open on every side, and bordered on two sides by +much-travelled thoroughfares, with electric cars passing every +hour, and seen by all the people living in the neighbourhood for +miles around, and by several hundred others, yet these flights +have been made by some newspapers the subject of a great +"mystery." ' + +Viewing their work from the financial side, the two brothers +incurred but little expense in the earlier gliding experiments, +and, indeed, viewed these only as recreation, limiting their +expenditure to that which two men might spend on any hobby. +When they had once achieved successful power-driven flight, they +saw the possibilities of their work, and abandoned such other +business as had engaged their energies, sinking all their +capital in the development of a practical flying machine. +Having, in 1905, improved their designs to such an extent that +they could consider their machine a practical aeroplane, they +devoted the years 1906 and 1907 to business negotiations and to +the construction of new machines, resuming flying experiments in +May of 1908 in order to test the ability of their machine to +meet the requirements of a contract they had made with the +United States Government, which required an aeroplane capable of +carrying two men, together with sufficient fuel supplies for a +flight of 125 miles at 40 miles per hour. Practically similar +to the machine used in the experiments of 1905, the contract +aeroplane was fitted with a larger motor, and provision was made +for seating a passenger and also for allowing of the operator +assuming a sitting position, instead of lying prone. + +Before leaving the work of the brothers to consider contemporary +events, it may be noted that they claimed--with justice--that +they were first to construct wings adjustable to different +angles of incidence on the right and left side in order to +control the balance of an aeroplane; the first to attain lateral +balance by adjusting wing-tips to respectively different angles +of incidence on the right and left sides, and the first to use a +vertical vane in combination with wing-tips, adjustable to +respectively different angles of incidence, in balancing and +steering an aeroplane. They were first, too, to use a movable +vertical tail, in combination with wings adjustable to different +angles of incidence, in controlling the balance and direction of +an aeroplane.[*] + +[*]Aeronautical Journal, No. 79. + +A certain Henry M. Weaver, who went to see the work of the +brothers, writing in a letter which was subsequently read before +the Aero Club de France records that he had a talk in 1905 with +the farmer who rented the field in which the Wrights made their +flights.' On October 5th (1905) he was cutting corn in the next +field east, which is higher ground. When he noticed the +aeroplane had started on its flight he remarked to his helper: +"Well, the boys are at it again," and kept on cutting corn, at +the same time keeping an eye on the great white form rushing +about its course. "I just kept on shocking corn," he continued, +"until I got down to the fence, and the durned thing was still +going round. I thought it would never stop." ' + +He was right. The brothers started it, and it will never stop. + +Mr Weaver also notes briefly the construction of the 1905 Wright +flier. 'The frame was made of larch wood-from tip to tip of the +wings the dimension was 40 feet. The gasoline motor--a special +construction made by them--much the same, though, as the motor +on the Pope-Toledo automobile--was of from 12 to 15 horse-power. +The motor weighed 240 lbs. The frame was covered with ordinary +muslin of good quality. No attempt was made to lighten the +machine; they simply built it strong enough to stand the shocks. +The structure stood on skids or runners, like a sleigh. These +held the frame high enough from the ground in alighting to +protect the blades of the propeller. Complete with motor, the +machine weighed 925 lbs. + + + +XII. THE FIRST YEARS OF CONQUEST + +It is no derogation of the work accomplished by the Wright +Brothers to say that they won the honour of the first +power-propelled flights in a heavier-than-air machine only by a +short period. In Europe, and especially in France, independent +experiment was being conducted by Ferber, by Santos-Dumont, and +others, while in England Cody was not far behind the other +giants of those days. The history of the early years of +controlled power flights is a tangle of half-records; there were +no chroniclers, only workers, and much of what was done goes +unrecorded perforce, since it was not set down at the time. + +Before passing to survey of those early years, let it be set +down that in 1907, when the Wright Brothers had proved the +practicability of their machines, negotiations were entered into +between the brothers and the British War office. On April 12th +1907, the apostle of military stagnation, Haldane, then War +Minister, put an end to the negotiations by declaring that 'the +War office is not disposed to enter into relations at present +with any manufacturer of aeroplanes' The state of the British +air service in 1914 at the outbreak of hostilities, is eloquent +regarding the pursuance of the policy which Haldane initiated. + +'If I talked a lot,' said Wilbur Wright once, 'I should be like +the parrot, which is the bird that speaks most and flies least.' +That attitude is emblematic of the majority of the early fliers, +and because of it the record of their achievements is incomplete +to-day. Ferber, for instance, has left little from which to +state what he did, and that little is scattered through various +periodicals, scrappily enough. A French army officer, Captain +Ferber was experimenting with monoplane and biplane gliders at +the beginning of the century-his work was contemporary with that +of the Wrights. He corresponded both with Chanute and with the +Wrights, and in the end he was commissioned by the French +Ministry of War to undertake the journey to America in order to +negotiate with the Wright Brothers concerning French rights in +the patents they had acquired, and to study their work at first +hand. + +Ferber's experiments in gliding began in 1899 at the Military +School at Fountainebleau, with a canvas glider of some 80 square +feet supporting surface, and weighing 65 lbs. Two years later +he constructed a larger and more satisfactory machine, with +which he made numerous excellent glides. Later, he constructed +an apparatus which suspended a plane from a long arm which swung +on a tower, in order that experiments might be carried out +without risk to the experimenter, and it was not until 1905 that +he attempted power-driven free flight. He took up the Voisin +design of biplane for his power-driven flights, and virtually +devoted all his energies to the study of aeronautics. His book, +Aviation, its Dawn and Development, is a work of scientific +value--unlike many of his contemporaries, Ferber brought to the +study of the problems of flight a trained mind, and he was +concerned equally with the theoretical problems of aeronautics +and the practical aspects of the subject. + +After Bleriot's successful cross-Channel flight, it was proposed +to offer a prize of L1,000 for the feat which C. S. Rolls +subsequently accomplished (starting from the English side of the +Channel), a flight from Boulogne to Dover and back; in place of +this, however, an aviation week at Boulogne was organised, but, +although numerous aviators were invited to compete, the +condition of the flying grounds was such that no competitions +took place. Ferber was virtually the only one to do any flying +at Boulogne, and at the outset he had his first accident; after +what was for those days a good flight, he made a series of +circles with his machine, when it suddenly struck the ground, +being partially wrecked. Repairs were carried out, and Ferber +resumed his exhibition flights, carrying on up to Wednesday, +September 22nd, 1909. On that day he remained in the air for +half an hour, and, as he was about to land, the machine struck a +mound of earth and overturned, pinning Ferber under the weight +of the motor. After being extricated, Ferber seemed to show +little concern at the accident, but in a few minutes he +complained of great pain, when he was conveyed to the ambulance +shed on the ground. + +'I was foolish,' he told those who were with him there. 'I was +flying too low. It was my own fault and it will be a severe +lesson to me. I wanted to turn round, and was only five metres +from the ground.' A little after this, he got up from the couch +on which he had been placed, and almost immediately collapsed, +dying five minutes later. + +Ferber's chief contemporaries in France were Santos-Dumont, of +airship fame, Henri and Maurice Farman, Hubert Latham, Ernest +Archdeacon, and Delagrange. These are names that come at once to +mind, as does that of Bleriot, who accomplished the second great +feat of power-driven flight, but as a matter of fact the years +1903-10 are filled with a little host of investigators and +experimenters, many of whom, although their names do not survive +to any extent, are but a very little way behind those mentioned +here in enthusiasm and devotion. Archdeacon and Gabriel Voisin, +the former of whom took to heart the success achieved by the +Wright Brothers, co-operated in experiments in gliding. +Archdeacon constructed a glider in box-kite fashion, and Voisin +experimented with it on the Seine, the glider being towed by a +motorboat to attain the necessary speed. It was Archdeacon who +offered a cup for the first straight flight of 200 metres, which +was won by Santos-Dumont, and he also combined with Henri Deutsch +de la Meurthe in giving the prize for the first circular flight +of a mile, which was won by Henry Farman on January 13th, 1908. + +A history of the development of aviation in France in these, the +strenuous years, would fill volumes in itself. Bleriot was +carrying out experiments with a biplane glider on the Seine, and +Robert Esnault-Pelterie was working on the lines of the Wright +Brothers, bringing American practice to France. In America +others besides the Wrights had wakened to the possibilities of +heavier-than-air flight; Glenn Curtiss, in company with Dr +Alexander Graham Bell, with J. A. D. McCurdy, and with F. W. +Baldwin, a Canadian engineer, formed the Aerial Experiment +Company, which built a number of aeroplanes, most famous of +which were the 'June Bug,' the 'Red Wing,' and the 'White Wing.' +In 1908 the 'June Bug 'won a cup presented by the Scientific +American--it was the first prize offered in America in +connection with aeroplane flight. + +Among the little group of French experimenters in these first +years of practical flight, Santos-Dumont takes high rank. He +built his 'No. 14 bis' aeroplane in biplane form, with two +superposed main plane surfaces, and fitted it with an +eight-cylinder Antoinette motor driving a two-bladed aluminium +propeller, of which the blades were 6 feet only from tip to tip. +The total lift surface of 860 square feet was given with a +wing-span of a little under 40 feet, and the weight of the +complete machine was 353 lbs., of which the engine weighed 158 +lbs. In July of 1906 Santos-Dumont flew a distance of a few +yards in this machine, but damaged it in striking the ground; on +October 23rd of the same year he made a flight of nearly 200 +feet--which might have been longer, but that he feared a crowd +in front of the aeroplane and cut off his ignition. This may be +regarded as the first effective flight in Europe, and by it +Santos-Dumont takes his place as one of the chief--if not the +chief--of the pioneers of the first years of practical flight, +so far as Europe is concerned. + +Meanwhile, the Voisin Brothers, who in 1904 made cellular kites +for Archdeacon to test by towing on the Seine from a motor +launch, obtained data for the construction of the aeroplane +which Delagrange and Henry Farman were to use later. The Voisin +was a biplane, constructed with due regard to the designs of +Langley, Lilienthal, and other earlier experimenters--both the +Voisins and M. Colliex, their engineer, studied Lilienthal +pretty exhaustively in getting out their design, though their +own researches were very thorough as well. The weight of this +Voisin biplane was about 1,450 lbs., and its maximum speed was +some 38 to 40 miles per hour, the total supporting surface being +about 535 square feet. It differed from the Wright design in +the possession of a tail-piece, a characteristic which marked +all the French school of early design as in opposition to the +American. The Wright machine got its longitudinal stability by +means of the main planes and the elevating planes, while the +Voisin type added a third factor of stability in its sailplanes. +Further, the Voisins fitted their biplane with a wheeled +undercarriage, while the Wright machine, being fitted only with +runners, demanded a launching rail for starting. Whether a +machine should be tailless or tailed was for some long time +matter for acute controversy, which in the end was settled by +the fitting of a tail to the Wright machines-France won the +dispute by the concession. + +Henry Farman, who began his flying career with a Voisin machine, +evolved from it the aeroplane which bore his name, following the +main lines of the Voisin type fairly closely, but making +alterations in the controls, and in the design of the +undercarriage, which was somewhat elaborated, even to the +inclusion of shock absorbers. The seven-cylinder 50 horse-power +Gnome rotary engine was fitted to the Farman machine--the +Voisins had fitted an eight-cylinder Antoinette, giving 50 +horse-power at 1,100 revolutions per minute, with direct drive +to the propeller. Farman reduced the weight of the machine from +the 1,450 lbs. of the Voisins to some 1,010 lbs. or +thereabouts, and the supporting area to 450 square feet. This +machine won its chief fame with Paulhan as pilot in the famous +London to Manchester flight--it is to be remarked, too, that +Farman himself was the first man in Europe to accomplish a +flight of a mile. + +Other notable designs of these early days were the 'R.E.P.', +Esnault Pelterie's machine, and the Curtiss-Herring biplane. Of +these Esnault Pelterie's was a monoplane, designed in that form +since Esnault Pelterie had found by experiment that the wire +used in bracing offers far more resistance to the air than its +dimensions would seem to warrant. He built the wings of +sufficient strength to stand the strain of flight without +bracing wires, and dependent only for their support on the +points of attachment to the body of the machine; for the rest, +it carried its propeller in front of the planes, and both +horizontal and vertical rudders at the stern--a distinct +departure from the Wright and similar types. One wheel only was +fixed under the body where the undercarriage exists on a normal +design, but light wheels were fixed, one at the extremity of +each wing, and there was also a wheel under the tail portion of +the machine. A single lever actuated all the controls for +steering. With a supporting surface of 150 square feet the +machine weighed 946 lbs., about 6.4 lbs. per square foot of +lifting surface. + +The Curtiss biplane, as flown by Glenn Curtiss at the Rheims +meeting, was built with a bamboo framework, stayed by means of +very fine steel-stranded cables. A--then--novel feature of the +machine was the moving of the ailerons by the pilot leaning to +one side or the other in his seat, a light, tubular arm-rest +being pressed by his body when he leaned to one side or the +other, and thus operating the movement of the ailerons employed +for tilting the plane when turning. A steering-wheel fitted +immediately in front of the pilot's seat served to operate a +rear steering-rudder when the wheel was turned in either +direction, while pulling back the wheel altered the inclination +of the front elevating planes, and so gave lifting or depressing +control of the plane. + +This machine ran on three wheels before leaving the ground, a +central undercarriage wheel being fitted in front, with two more +in line with a right angle line drawn through the centre of the +engine crank at the rear end of the crank-case. The engine was +a 35 horsepower Vee design, water cooled, with overhead inlet +and exhaust valves, and Bosch high-tension magneto ignition. +The total weight of the plane in flying order was about 700 lbs. + +As great a figure in the early days as either Ferber or +Santos-Dumont was Louis Bleriot, who, as early as 1900 built a +flapping-wing model, this before ever he came to experimenting +with the Voisin biplane type of glider on the Seine. Up to 1906 +he had built four biplanes of his own design, and in March of +1907 he built his first monoplane, to wreck it only a few days +after completion in an accident from which he had a fortunate +escape. His next machine was a double monoplane, designed after +Langley's precept, to a certain extent, and this was totally +wrecked in September of 1907. His seventh machine, a +monoplane, was built within a month of this accident, and with +this he had a number of mishaps, also achieving some good +flights, including one in which he made a turn. It was wrecked +in December of 1907, whereupon he built another monoplane on +which, on July 6th, 1908, Bleriot made a flight lasting eight +and a half minutes. In October of that year he flew the machine +from Toury to Artenay and returned on it--this was just a day +after Farman's first cross-country flight--but, trying to repeat +the success five days later, Bleriot collided with a tree in a +fog and wrecked the machine past repair. Thereupon he set about +building his eleventh machine, with which he was to achieve the +first flight across the English channel. + +Henry Farman, to whom reference has already been made, was +engaged with his two brothers, Maurice and Richard, in the +motor-car business, and turned to active interest in flying in +1907, when the Voisin firm built his first biplane on the +box-kite principle. In July of 1908 he won a prize of L400 for +a flight of thirteen miles, previously having completed the +first kilometre flown in Europe with a passenger, the said +passenger being Ernest Archdeaon. In September of 1908 Farman +put up a speed record of forty miles an hour in a flight lasting +forty minutes. + +Santos-Dumont produced the famous 'Demoiselle' monoplane early +in 1909, a tiny machine in which the pilot had his seat in a +sort of miniature cage under the main plane. It was a very +fast, light little machine but was difficult to fly, and owing +to its small wingspread was unable to glide at a reasonably safe +angle. There has probably never been a cheaper flying machine +to build than the 'Demoiselle,' which could be so upset as to +seem completely wrecked, and then repaired ready for further +flight by a couple of hours' work. Santos-Dumont retained no +patent in the design, but gave it out freely to any one who +chose to build 'Demoiselles'; the vogue of the pattern was +brief, owing to the difficulty of piloting the machine. + +These were the years of records, broken almost as soon as made. +There was Farman's mile, there was the flight of the Comte de +Lambert over the Eiffel Tower, Latham's flight at Blackpool in a +high wind, the Rheims records, and then Henry Farman's flight of +four hours later in 1909, Orville Wright's height record of +1,640 feet, and Delagrange's speed record of 49.9 miles per +hour. The coming to fame of the Gnome rotary engine helped in +the making of these records to a very great extent, for in this +engine was a prime mover which gave the reliability that +aeroplane builders and pilots had been searching for, but +vainly. The Wrights and Glenn Curtiss, of course, had their own +designs of engine, but the Gnome, in spite of its lack of +economy in fuel and oil, and its high cost, soon came to be +regarded as the best power plant for flight. + +Delagrange, one of the very good pilots of the early days, +provided a curious insight to the way in which flying was +regarded, at the opening of the Juvisy aero aerodrome in May of +1909. A huge crowd had gathered for the first day's flying, and +nine machines were announced to appear, but only three were +brought out. Delagrange made what was considered an indifferent +little flight, and another pilot, one De Bischoff, attempted to +rise, but could not get his machine off the ground. Thereupon +the crowd of 30,000 people lost their tempers, broke down the +barriers surrounding the flying course, and hissed the +officials, who were quite unable to maintain order. Delagrange, +however, saved the situation by making a circuit of the course +at a height of thirty feet from the ground, which won him rounds +of cheering and restored the crowd to good humour. Possibly the +smash achieved by Rougier, the famous racing motorist, who +crashed his Voisin biplane after Delagrange had made his +circuit, completed the enjoyment of the spectators. Delagrange, +flying at Argentan in June of 1909, made a flight of four +kilometres at a height of sixty feet; for those days this was a +noteworthy performance. Contemporary with this was Hubert +Latham's flight of an hour and seven minutes on an Antoinette +monoplane; this won the adjective 'magnificent' from +contemporary recorders of aviation. + +Viewing the work of the little group of French experimenters, it +is, at this length of time from their exploits, difficult to see +why they carried the art as far as they did. There was in it +little of satisfaction, a certain measure of fame, and +practically no profit--the giants of those days got very little +for their pains. Delagrange's experience at the opening of the +Juvisy ground was symptomatic of the way in which flight was +regarded by the great mass of people--it was a sport, and +nothing more, but a sport without the dividends attaching to +professional football or horse-racing. For a brief period, +after the Rheims meeting, there was a golden harvest to be +reaped by the best of the pilots. Henry Farman asked L2,000 for +a week's exhibition flying in England, and Paulhan asked half +that sum, but a rapid increase in the number of capable pilots, +together with the fact that most flying meetings were financial +failures, owing to great expense in organisation and the +doubtful factor of the weather, killed this goose before many +golden eggs had been gathered in by the star aviators. Besides, +as height and distance records were broken one after another, it +became less and less necessary to pay for entrance to an +aerodrome in order to see a flight--the thing grew too big for a +mere sports ground. + +Long before Rheims and the meeting there, aviation had grown too +big for the chronicling of every individual effort. In that +period of the first days of conquest of the air, so much was +done by so many whose names are now half-forgotten that it is +possible only to pick out the great figures and make brief +reference to their achievements and the machines with which they +accomplished so much, pausing to note such epoch-making events +as the London-Manchester flight, Bleriot's Channel crossing, and +the Rheims meeting itself, and then passing on beyond the days +of individual records to the time when the machine began to +dominate the man. This latter because, in the early days, it +was heroism to trust life to the planes that were turned out +--the 'Demoiselle' and the Antoinette machine that Latham used +in his attempt to fly the Channel are good examples of the +flimsiness of early types--while in the later period, that of +the war and subsequently, the heroism turned itself in a +different--and nobler-direction. Design became standardised, +though not perfected. The domination of the machine may best be +expressed by contrasting the way in which machines came to be +regarded as compared with the men who flew them: up to 1909, +flying enthusiasts talked of Farman, of Bleriot, of Paulhan, +Curtiss, and of other men; later, they began to talk of the +Voisin, the Deperdussin, and even to the Fokker, the Avro, and +the Bristol type. With the standardising of the machine, the +days of the giants came to an end. + + + +XIII. FIRST FLIERS IN ENGLAND + +Certain experiments made in England by Mr Phillips seem to have +come near robbing the Wright Brothers of the honour of the first +flight; notes made by Colonel J. D. Fullerton on the Phillips +flying machine show that in 1893 the first machine was built +with a length of 25 feet, breadth of 22 feet, and height of 11 +feet, the total weight, including a 72 lb. load, being 420 lbs. +The machine was fitted with some fifty wood slats, in place of +the single supporting surface of the monoplane or two superposed +surfaces of the biplane, these slats being fixed in a steel +frame so that the whole machine rather resembled a Venetian +blind. A steam engine giving about 9 horse-power provided the +motive power for the six-foot diameter propeller which drove the +machine. As it was not possible to put a passenger in control +as pilot, the machine was attached to a central post by wire +guys and run round a circle 100 feet in diameter, the track +consisting of wooden planking 4 feet wide. Pressure of air +under the slats caused the machine to rise some two or three +feet above the track when sufficient velocity had been attained, +and the best trials were made on June 19th 1893, when at a speed +of 40 miles an hour, with a total load of 385 lbs., all the +wheels were off the ground for a distance of 2,000 feet. + +In 1904 a full-sized machine was constructed by Mr Phillips, +with a total weight, including that of the pilot, of 600 lbs. +The machine was designed to lift when it had attained a velocity +of 50 feet per second, the motor fitted giving 22 horse-power. +On trial, however, the longitudinal equilibrium was found to be +defective, and a further design was got out, the third machine +being completed in 1907. In this the wood slats were held in +four parallel container frames, the weight of the machine, +excluding the pilot, being 500 lbs. A motor similar to that +used in the 1904 machine was fitted, and the machine was +designed to lift at a velocity of about 30 miles an hour, a +seven-foot propeller doing the driving. Mr Phillips tried out +this machine in a field about 400 yards across. 'The machine +was started close to the hedge, and rose from the ground when +about 200 yards had been covered. When the machine touched the +ground again, about which there could be no doubt, owing to the +terrific jolting, it did not run many yards. When it came to +rest I was about ten yards from the boundary. Of course, I +stopped the engine before I commenced to descend.'[*] + +[*] Aeronautical Journal, July, 1908. + +S. F. Cody, an American by birth, aroused the attention not only +of the British public, but of the War office and Admiralty as +well, as early as 1905 with his man-lifting kites. In that year +a height of 1,600 feet was reached by one of these box-kites, +carrying a man, and later in the same year one Sapper Moreton, +of the Balloon Section of the Royal Engineers (the parent of the +Royal Flying Corps) remained for an hour at an altitude of 2,600 +feet. Following on the success of these kites, Cody constructed +an aeroplane which he designated a 'power kite,' which was in +reality a biplane that made the first flight in Great Britain. +Speaking before the Aeronautical Society in 1908, Cody said that +'I have accomplished one thing that I hoped for very much, that +is, to be the first man to fly in Great Britain.... I made a +machine that left the ground the first time out; not high, +possibly five or six inches only. I might have gone higher if I +wished. I made some five flights in all, and the last flight +came to grief.... On the morning of the accident I went out +after adjusting my propellers at 8 feet pitch running at 600 +(revolutions per minute). I think that I flew at about +twenty-eight miles per hour. I had 50 horsepower motor power in +the engine. A bunch of trees, a flat common above these trees, +and from this flat there is a slope goes down... to another clump +of trees. Now, these clumps of trees are a quarter of a mile +apart or thereabouts.... I was accused of doing nothing but +jumping with my machine, so I got a bit agitated and went to fly. + +I went out this morning with an easterly wind, and left the +ground at the bottom of the hill and struck the ground at the +top, a distance of 74 yards. That proved beyond a doubt that the +machine would fly--it flew uphill. That was the most talented +flight the machine did, in my opinion. Now, I turned round at +the top and started the machine and left the ground--remember, a +ten mile wind was blowing at the time. Then, 60 yards from where +the men let go, the machine went off in this direction +(demonstrating)--I make a line now where I hoped to land--to cut +these trees off at that side and land right off in here. I got +here somewhat excited, and started down and saw these trees right +in front of me. I did not want to smash my head rudder to +pieces, so I raised it again and went up. I got one wing direct +over that clump of trees, the right wing over the trees, the left +wing free; the wind, blowing with me, had to lift over these +trees. So I consequently got a false lift on the right side and +no lift on the left side. Being only about 8 feet from the tree +tops, that turned my machine up like that (demonstrating). This +end struck the ground shortly after I had passed the trees. I +pulled the steering handle over as far as I could. Then I faced +another bunch of trees right in front of me. Trying to avoid +this second bunch of trees I turned the rudder, and turned it +rather sharp. That side of the machine struck, and it crumpled +up like so much tissue paper, and the machine spun round and +struck the ground that way on, and the framework was considerably +wrecked. Now, I want to advise all aviators not to try to fly +with the wind and to cross over any big clump of earth or any +obstacle of any description unless they go square over the top of +it, because the lift is enormous crossing over anything like +that, and in coming the other way against the wind it would be +the same thing when you arrive at the windward side of the +obstacle. That is a point I did not think of, and had I thought +of it I would have been more cautious.' + +This Cody machine was a biplane with about 40 foot span, the +wings being about 7 feet in depth with about 8 feet between +upper and lower wing surfaces. 'Attached to the extremities of +the lower planes are two small horizontal planes or rudders, +while a third small vertical plane is fixed over the centre of +the upper plane.' The tail-piece and principal rudder were +fitted behind the main body of the machine, and a horizontal +rudder plane was rigged out in front, on two supporting arms +extending from the centre of the machine. The small end-planes +and the vertical plane were used in conjunction with the main +rudder when turning to right or left, the inner plane being +depressed on the turn, and the outer one correspondingly raised, +while the vertical plane, working in conjunction, assisted in +preserving stability. Two two-bladed propellers were driven by +an eight-cylinder 50 horse-power Antoinette motor. With this +machine Cody made his first flights over Laffan's plain, being +then definitely attached to the Balloon Section of the Royal +Engineers as military aviation specialist. + +There were many months of experiment and trial, after the +accident which Cody detailed in the statement given above, and +then, on May 14th, 1909, Cody took the air and made a flight of +1,200 yards with entire success. Meanwhile A. V. Roe was +experimenting at Lea Marshes with a triplane of rather curious +design the pilot having his seat between two sets of three +superposed planes, of which the front planes could be tilted and +twisted while the machine was in motion. He comes but a little +way after Cody in the chronology of early British experimenters, +but Cody, a born inventor, must be regarded as the pioneer of +the present century so far as Britain is concerned. He was +neither engineer nor trained mathematician, but he was a good +rule-of-thumb mechanic and a man of pluck and perseverance; he +never strove to fly on an imperfect machine, but made alteration +after alteration in order to find out what was improvement and +what was not, in consequence of which it was said of him that he +was 'always satisfied with his alterations.' + +By July of 1909 he had fitted an 80 horse-power motor to his +biplane, and with this he made a flight of over four miles over +Laffan's Plain on July 21st. By August he was carrying +passengers, the first being Colonel Capper of the R.E. Balloon +Section, who flew with Cody for over two miles, and on September +8th, 1909, he made a world's record cross-country flight of +over forty miles in sixty-six minutes, taking a course from +Laffan's Plain over Farnborough, Rushmoor, and Fleet, and back +to Laffan's Plain. He was one of the competitors in the 1909 +Doncaster Aviation Meeting, and in 1910 he competed at +Wolverhampton, Bournemouth, and Lanark. It was on June 7th, +1910, that he qualified for his brevet, No. 9, on the Cody +biplane. + +He built a machine which embodied all the improvements for which +he had gained experience, in 1911, a biplane with a length of +35 feet and span of 43 feet, known as the 'Cody cathedral' on +account of its rather cumbrous appearance. With this, in 1911, +he won the two Michelin trophies presented in England, completed +the Daily Mail circuit of Britain, won the Michelin +cross-country prize in 1912 and altogether, by the end of 1912, +had covered more than 7,000 miles with the machine. It was +fitted with a 120 horse-power Austro-Daimler engine, and was +characterised by an exceptionally wide range of speed--the great +wingspread gave a slow landing speed. + +A few of his records may be given: in 1910, flying at Laffan's +Plain in his biplane, fitted with a 50-60 horsepower Green +engine, on December 31st, he broke the records for distance and +time by flying 185 miles, 787 yards, in 4 hours 37 minutes. On +October 31st, 1911, he beat this record by flying for 5 hours 15 +minutes, in which period he covered 261 miles 810 yards with a 60 +horse-power Green engine fitted to his biplane. In 1912, +competing in the British War office tests of military +aeroplanes, he won the L5,000 offered by the War Office. This +was in competition with no less than twenty-five other machines, +among which were the since-famous Deperdussin, Bristol, +Flanders, and Avro types, as well as the Maurice Farman and +Bleriot makes of machine. Cody's remarkable speed range was +demonstrated in these trials, the speeds of his machine varying +between 72.4 and 48.5 miles per hour. The machine was the only +one delivered for the trials by air, and during the three hours' +test imposed on all competitors a maximum height of 5,000 feet +was reached, the first thousand feet being achieved in three and +a half minutes. + +During the summer of 1913 Cody put his energies into the +production of a large hydro-biplane, with which he intended to +win the L5,000 prize offered by the Daily Mail to the first +aviator to fly round Britain on a waterplane. This machine was +fitted with landing gear for its tests, and, while flying it +over Laffan's Plain on August 7th, 1913, with Mr W. H. B. Evans +as passenger, Cody met with the accident that cost both +him and his passenger their lives. Aviation lost a great figure +by his death, for his plodding, experimenting, and dogged +courage not only won him the fame that came to a few of the +pilots of those days, but also advanced the cause of flying very +considerably and contributed not a little to the sum of +knowledge in regard to design and construction. + +Another figure of the early days was A. V. Roe, who came from +marine engineering to the motor industry and aviation in 1905. +In 1906 he went out to Colorado, getting out drawings for the +Davidson helicopter, and in 1907 having returned to England, he +obtained highest award out of 200 entries in a model aeroplane +flying competition. From the design of this model he built a +full-sized machine, and made a first flight on it, fitted with a +24 horse-power Antoinette engine, in June of 1908 Later, he +fitted a 9 horsepower motor-cycle engine to a triplane of his +own design, and with this made a number of short flights; he got +his flying brevet on a triplane with a motor of 35 horse-power, +which, together with a second triplane, was entered for the +Blackpool aviation meeting of 1910 but was burnt in transport to +the meeting. He was responsible for the building of the first +seaplane to rise from English waters, and may be counted the +pioneer of the tractor type of biplane. In 1913 he built a +two-seater tractor biplane with 80 horse-power engine, a machine +which for some considerable time ranked as a leader of design. +Together with E. V. Roe and H. V. Roe, 'A. V.' controlled the +Avro works, which produced some of the most famous training +machines of the war period in a modification of the original 80 +horse-power tractor. The first of the series of Avro tractors +to be adopted by the military authorities was the 1912 biplane, a +two-seater fitted with 50 horsepower engine. It was the first +tractor biplane with a closed fuselage to be used for military +work, and became standard for the type. The Avro seaplane, of I +100 horse-power (a fourteen-cylinder Gnome engine was used) was +taken up by the British Admiralty in 1913. It had a length of 34 +feet and a wing-span of 50 feet, and was of the twin-float type. + +Geoffrey de Havilland, though of later rank, counts high among +designers of British machines. He qualified for his brevet as +late as February, 1911, on a biplane of his own construction, and +became responsible for the design of the BE2, the first +successful British Government biplane. On this he made a British +height record of 10,500 feet over Salisbury Plain, in August of +1912, when he took up Major Sykes as passenger. In the war +period he was one of the principal designers of fighting and +reconnaissance machines. + +F. Handley Page, who started in business as an aeroplane +builder in 1908, having works at Barking, was one of the +principal exponents of the inherently stable machine, to which +he devoted practically all his experimental work up to the +outbreak of war. The experiments were made with various +machines, both of monoplane and biplane type, and of these one +of the best was a two-seater monoplane built in 1911, while a +second was a larger machine, a biplane, built in 1913 and fitted +with a 110 horse-power Anzani engine. The war period brought out +the giant biplane with which the name of Handley Page is most +associated, the twin-engined night-bomber being a familiar +feature of the later days of the war; the four-engined bomber had +hardly had a chance of proving itself under service conditions +when the war came to an end. + +Another notable figure of the early period was 'Tommy' Sopwith, +who took his flying brevet at Brooklands in November of 1910, +and within four days made the British duration record of 108 +miles in 3 hours 12 minutes. On December 18th, 1910, he won the +Baron de Forrest prize of L4,000 for the longest flight from +England to the Continent, flying from Eastchurch to Tirlemont, +Belgium, in three hours, a distance of 161 miles. After two +years of touring in America, he returned to England and +established a flying school. In 1912 he won the first aerial +Derby, and in 1913 a machine of his design, a tractor biplane, +raised the British height record to 13,000 feet (June 16th, at +Brooklands). First as aviator, and then as designer, Sopwith has +done much useful work in aviation. + +These are but a few, out of a host who contributed to the +development of flying in this country, for, although France may +be said to have set the pace as regards development, Britain was +not far behind. French experimenters received far more +Government aid than did the early British aviators and +designers--in the early days the two were practically +synonymous, and there are many stories of the very early days at +Brooklands, where, when funds ran low, the ardent spirits +patched their trousers with aeroplane fabric and went on with +their work with Bohemian cheeriness. Cody, altering and +experimenting on Laffan's Plain, is the greatest figure of them +all, but others rank, too, as giants of the early days, before +the war brought full recognition of the aeroplane's +potentialities. + +one of the first men actually to fly in England, Mr J. C. T. +Moore-Brabazon, was a famous figure in the days of exhibition +flying, and won his reputation mainly through being first to fly +a circular mile on a machine designed and built in Great Britain +and piloted by a British subject. Moore-Brabazon's earliest +flights were made in France on a Voisin biplane in 1908, and he +brought this machine over to England, to the Aero Club grounds +at Shellness, but soon decided that he would pilot a British +machine instead. An order was placed for a Short machine, and +this, fitted with a 50-60 horse-power Green engine, was used for +the circular mile, which won a prize of L1,000 offered by the +Daily Mail, the feat being accomplished on October 30th, 1909. +Five days later, Moore-Brabazon achieved the longest flight up +to that time accomplished on a British-built machine, covering +three and a half miles. In connection with early flying in +England, it is claimed that A. V. Roe, flying 'Avro B,',' on +June 8th, 1908, was actually the first man to leave the ground, +this being at Brooklands, but in point of fact Cody antedated +him. + +No record of early British fliers could be made without the name +of C. S. Rolls, a son of Lord Llangattock, on June 2nd, 1910, +he flew across the English Channel to France, until he was duly +observed over French territory, when he returned to England +without alighting. The trip was made on a Wright biplane, and +was the third Channel crossing by air, Bleriot having made the +first, and Jacques de Lesseps the second. Rolls was first to +make the return journey in one trip. He was eventually killed +through the breaking of the tail-plane of his machine in +descending at a flying meeting at Bournemouth. The machine was +a Wright biplane, but the design of the tail-plane--which, by +the way, was an addition to the machine, and was not even +sanctioned by the Wrights--appears to have been carelessly +executed, and the plane itself was faulty in construction. The +breakage caused the machine to overturn, killing Rolls, who was +piloting it. + + + +XIV. RHEIMS, AND AFTER + +The foregoing brief--and necessarily incomplete--survey of the +early British group of fliers has taken us far beyond some of +the great events of the early days of successful flight, and it +is necessary to go back to certain landmarks in the history of +aviation, first of which is the great meeting at Rheims in 1909. +Wilbur Wright had come to Europe, and, flying at Le Mans and +Pau--it was on August 8th, 1908, that Wilbur Wright made the +first of his ascents in Europe--had stimulated public interest +in flying in France to a very great degree. Meanwhile, Orville +Wright, flying at Fort Meyer, U.S.A., with Lieutenant Selfridge +as a passenger, sustained an accident which very nearly cost him +his life through the transmission gear of the motor breaking. +Selfridge was killed and Orville Wright was severely injured--it +was the first fatal accident with a Wright machine. + +Orville Wright made a flight of over an hour on September 9th, +1908, and on December 31st of that year Wilbur flew for 2 hours +19 minutes. Thus, when the Rheims meeting was organised--more +notable because it was the first of its kind, there were already +records waiting to be broken. The great week opened on August +22nd, there being thirty entrants, including all the most famous +men among the early fliers in France. Bleriot, fresh from his +Channel conquest, was there, together with Henry Farman, +Paulhan, Curtiss, Latham, and the Comte de Lambert, first pupil +of the Wright machine in Europe to achieve a reputation as an +aviator. + +'To say that this week marks an epoch in the history of the +world is to state a platitude. Nevertheless, it is worth +stating, and for us who are lucky enough to be at Rheims during +this week there is a solid satisfaction in the idea that we are +present at the making of history. In perhaps only a few years +to come the competitions of this week may look pathetically +small and the distances and speeds may appear paltry. +Nevertheless, they are the first of their kind, and that is +sufficient.' + +So wrote a newspaper correspondent who was present at the famous +meeting, and his words may stand, being more than mere +journalism; for the great flying week which opened on August +22nd, 1909, ranks as one of the great landmarks in the history +of heavier-than-air flight. The day before the opening of the +meeting a downpour of rain spoilt the flying ground; Sunday +opened with a fairly high wind, and in a lull M. Guffroy turned +out on a crimson R.E.P. monoplane, but the wheels of his +undercarriage stuck in the mud and prevented him from rising in +the quarter of an hour allowed to competitors to get off the +ground. Bleriot, following, succeeded in covering one side of +the triangular course, but then came down through grit in the +carburettor. Latham, following him with thirteen as the number +of his machine, experienced his usual bad luck and came to earth +through engine trouble after a very short flight. Captain +Ferber, who, owing to military regulations, always flew under +the name of De Rue, came out next with his Voisin biplane, but +failed to get off the ground; he was followed by Lefebvre on a +Wright biplane, who achieved the success of the morning by +rounding the course--a distance of six and a quarter miles--in +nine minutes with a twenty mile an hour wind blowing. His +flight finished the morning. + +Wind and rain kept competitors out of the air until the evening, +when Latham went up, to be followed almost immediately by the +Comte de Lambert. Sommer, Cockburn (the only English +competitor), Delagrange, Fournier, Lefebvre, Bleriot, +Bunau-Varilla, Tissandier, Paulhan, and Ferber turned out after +the first two, and the excitement of the spectators at seeing so +many machines in the air at one time provoked wild cheering. +The only accident of the day came when Bleriot damaged his +propeller in colliding with a haycock. + +The main results of the day were that the Comte de Lambert flew +30 kilometres in 29 minutes 2 seconds; Lefebvre made the +ten-kilometre circle of the track in just a second under 9 +minutes, while Tissandier did it in 9 1/4 minutes, and Paulhan +reached a height of 230 feet. Small as these results seem to us +now, and ridiculous as may seem enthusiasm at the sight of a few +machines in the air at the same time, the Rheims Meeting remains +a great event, since it proved definitely to the whole world +that the conquest of the air had been achieved. + +Throughout the week record after record was made and broken. +Thus on the Monday, Lefebvre put up a record for rounding the +course and Bleriot beat it, to be beaten in turn by Glenn +Curtiss on his Curtiss-Herring biplane. On that day, too, +Paulhan covered 34 3/4 miles in 1 hour 6 minutes. On the next +day, Paulhan on his Voisin biplane took the air with Latham, and +Fournier followed, only to smash up his machine by striking an +eddy of wind which turned him over several times. On the +Thursday, one of the chief events was Latham's 43 miles +accomplished in 1 hour 2 minutes in the morning and his 96.5 +miles in 2 hours 13 minutes in the afternoon, the latter flight +only terminated by running out of petrol. On the Friday, the +Colonel Renard French airship, which had flown over the ground +under the pilotage of M. Kapfarer, paid Rheims a second visit; +Latham manoeuvred round the airship on his Antoinette and finally +left it far behind. Henry Farman won the Grand Prix de Champagne +on this day, covering 112 miles in 3 hours, 4 minutes, 56 +seconds, Latham being second with his 96.5 miles flight, and +Paulhan third. + +On the Saturday, Glenn Curtiss came to his own, winning the +Gordon-Bennett Cup by covering 20 kilometres in 15 minutes +50.6 seconds. Bleriot made a good second with 15 minutes 56.2 +seconds as his time, and Latham and Lefebvre were third and +fourth. Farman carried off the passenger prize by carrying two +passengers a distance of 6 miles in 10 minutes 39 seconds. On +the last day Delagrange narrowly escaped serious accident +through the bursting of his propeller while in the air, Curtiss +made a new speed record by travelling at the rate of over 50 +miles an hour, and Latham, rising to 500 feet, won the altitude +prize. + +These are the cold statistics of the meeting; at this length of +time it is difficult to convey any idea of the enthusiasm of the +crowds over the achievements of the various competitors, while +the incidents of the week, comic and otherwise, are nearly +forgotten now even by those present in this making of history. +Latham's great flight on the Thursday was rendered a breathless +episode by a downpour of rain when he had covered all but a +kilometre of the record distance previously achieved by Paulhan, +and there was wild enthusiasm when Latham flew on through the +rain until he had put up a new record and his petrol had run +out. Again, on the Friday afternoon, the Colonel Renard took +the air together with a little French dirigible, Zodiac III; +Latham was already in the air directly over Farman, who was also +flying, and three crows which turned out as rivals to the human +aviators received as much cheering for their appearance as had +been accorded to the machines, which doubtless they could not +understand. Frightened by the cheering, the crows tried to +escape from the course, but as they came near the stands, the +crowd rose to cheer again and the crows wheeled away to make a +second charge towards safety, with the same result; the crowd +rose and cheered at them a third and fourth time; between ten +and fifteen thousand people stood on chairs and tables and waved +hats and handkerchiefs at three ordinary, everyday crows. One +thoughtful spectator, having thoroughly enjoyed the funny side +of the incident, remarked that the ultimate mastery of the air +lies with the machine that comes nearest to natural flight. +This still remains for the future to settle. + +Farman's world record, which won the Grand Prix de Champagne, +was done with a Gnome Rotary Motor which had only been run on +the test bench and was fitted to his machine four hours before +he started on the great flight. His propeller had never been +tested, having only been completed the night before. The +closing laps of that flight, extending as they did into the +growing of the dusk, made a breathlessly eerie experience for +such of the spectators as stayed on to watch--and these were +many. Night came on steadily and Farman covered lap after lap +just as steadily, a buzzing, circling mechanism with something +relentless in its isolated persistency. + +The final day of the meeting provided a further record in the +quarter million spectators who turned up to witness the close of +the great week. Bleriot, turning out in the morning, made a +landing in some such fashion as flooded the carburettor and +caused it to catch fire. Bleriot himself was badly burned, +since the petrol tank burst and, in the end, only the metal +parts of the machine were left. Glenn Curtis tried to beat +Bleriot's time for a lap of the course, but failed. In the +evening, Farman and Latham went out and up in great circles, +Farman cleaving his way upward in what at the time counted for a +huge machine, on circles of about a mile diameter. His first +round took him level with the top of the stands, and, in his +second, he circled the captive balloon anchored in the middle of +the grounds. After another circle, he came down on a long glide, +when Latham's lean Antoinette monoplane went up in circles more +graceful than those of Farman. 'Swiftly it rose and swept round +close to the balloon, veered round to the hangars, and out over +to the Rheims road. Back it came high over the stands, the +people craning their necks as the shrill cry of the engine drew +nearer and nearer behind the stands. Then of a sudden, the +little form appeared away up in the deep twilight blue vault of +the sky, heading straight as an arrow for the anchored balloon. +Over it, and high, high above it went the Antoinette, seemingly +higher by many feet than the Farman machine. Then, wheeling in +a long sweep to the left, Latham steered his machine round past +the stands, where the people, their nerve-tension released on +seeing the machine descending from its perilous height of 500 +feet, shouted their frenzied acclamations to the hero of the +meeting. + +'For certainly "Le Tham," as the French call him, was the +popular hero. He always flew high, he always flew well, and his +machine was a joy to the eye, either afar off or at close +quarters. The public feeling for Bleriot is different. +Bleriot, in the popular estimation, is the man who fights +against odds, who meets the adverse fates calmly and with good +courage, and to whom good luck comes once in a while as a reward +for much labour and anguish, bodily and mental. Latham is the +darling of the Gods, to whom Fate has only been unkind in the +matter of the Channel flight, and only then because the honour +belonged to Bleriot. + +'Next to these two, the public loved most Lefebvre, the joyous, +the gymnastic. Lefebvre was the comedian of the meeting. When +things began to flag, the gay little Lefebvre would trot out to +his starting rail, out at the back of the judge's enclosure +opposite the stands, and after a little twisting of propellers +his Wright machine would bounce off the end of its starting rail +and proceed to do the most marvellous tricks for the benefit of +the crowd, wheeling to right and left, darting up and down, now +flying over a troop of the cavalry who kept the plain clear of +people and sending their horses into hysterics, anon making +straight for an unfortunate photographer who would throw himself +and his precious camera flat on the ground to escape +annihilation as Lefebvre swept over him 6 or 7 feet off the +ground. Lefebvre was great fun, and when he had once found that +his machine was not fast enough to compete for speed with the +Bleriots, Antoinettes, and Curtiss, he kept to his metier of +amusing people. The promoters of the meeting owe Lefebvre a +debt of gratitude, for he provided just the necessary comic +relief.'--(The Aero, September 7th, 1909.) + +It may be noted, in connection with the fact that Cockburn was +the only English competitor at the meeting, that the Rheims +Meeting did more than anything which had preceded it to waken +British interest in aviation. Previously, heavier-than-air +flight in England had been regarded as a freak business by the +great majority, and the very few pioneers who persevered toward +winning England a share in the conquest of the air came in for +as much derision as acclamation. Rheims altered this; it taught +the world in general, and England in particular, that a serious +rival to the dirigible balloon had come to being, and it +awakened the thinking portion of the British public to the fact +that the aeroplane had a future. + +The success of this great meeting brought about a host of +imitations of which only a few deserve bare mention since, +unlike the first, they taught nothing and achieved little. +There was the meeting at Boulogne late in September of 1909, of +which the only noteworthy event was Ferber's death. There was a +meeting at Brescia where Curtiss again took first prize for +speed and Rougier put up a world's height record of 645 feet. +The Blackpool meeting followed between 18th and 23rd of +October, 1909, forming, with the exception of Doncaster, the +first British Flying Meeting. Chief among the competitors were +Henry Farman, who took the distance prize, Rougier, Paulhan, and +Latham, who, by a flight in a high wind, convinced the British +public that the theory that flying was only possible in a calm +was a fallacy. A meeting at Doncaster was practically +simultaneous with the Blackpool week; Delagrange, Le Blon, +Sommer, and Cody were the principal figures in this event. It +should be added that 130 miles was recorded as the total flown +at Doncaster, while at Blackpool only 115 miles were flown. +Then there were Juvisy, the first Parisian meeting, +Wolverhampton, and the Comte de Lambert's flight round the +Eiffel Tower at a height estimated at between 1,200 and 1,300 +feet. This may be included in the record of these aerial +theatricals, since it was nothing more. + +Probably wakened to realisation of the possibilities of the +aeroplane by the Rheims Meeting, Germany turned out its first +plane late in 1909. It was known as the Grade monoplane, and +was a blend of the Bleriot and Santos-Dumont machines, with a +tail suggestive of the Antoinette type. The main frame took the +form of a single steel tube, at the forward end of which was +rigged a triangular arrangement carrying the pilot's seat and +the landing wheels underneath, with the wing warping wires and +stays above. The sweep of the wings was rather similar to the +later Taube design, though the sweep back was not so pronounced, +and the machine was driven by a four-cylinder, 20 horse-power, +air-cooled engine which drove a two-bladed tractor propeller. +In spite of Lilienthal's pioneer work years before, this was the +first power-driven German plane which actually flew. + +Eleven months after the Rheims meeting came what may be reckoned +the only really notable aviation meeting on English soil, in the +form of the Bournemouth week, July 10th to 16th, 1910. This +gathering is noteworthy mainly in view of the amazing advance +which it registered on the Rheims performances. Thus, in the +matter of altitude, Morane reached 4,107 feet and Drexel came +second with 2,490 feet. Audemars on a Demoiselle monoplane made +a flight of 17 miles 1,480 yards in 27 minutes 17.2 seconds, a +great flight for the little Demoiselle. Morane achieved a speed +of 56.64 miles per hour, and Grahame White climbed to 1,000 feet +altitude in 6 minutes 36.8 seconds. Machines carrying the Gnome +engine as power unit took the great bulk of the prizes, and +British-built engines were far behind. + +The Bournemouth Meeting will always be remembered with regret +for the tragedy of C. S. Rolls's death, which took place on +the Tuesday, the second day of the meeting. The first +competition of the day was that for the landing prize; Grahame +White, Audemars, and Captain Dickson had landed with varying +luck, and Rolls, following on a Wright machine with a tail-plane +which ought never to have been fitted and was not part of the +Wright design, came down wind after a left-hand turn and turned +left again over the top of the stands in order to land up wind. +He began to dive when just clear of the stands, and had dropped +to a height of 40 feet when he came over the heads of the people +against the barriers. Finding his descent too steep, he pulled +back his elevator lever to bring the nose of the machine up, +tipping down the front end of the tail to present an almost flat +surface to the wind. Had all gone well, the nose of the machine +would have been forced up, but the strain on the tail and its +four light supports was too great; the tail collapsed, the wind +pressed down the biplane elevator, and the machine dived +vertically for the remaining 20 feet of the descent, hitting the +ground vertically and crumpling up. Major Kennedy, first to +reach the debris, found Rolls lying with his head doubled under +him on the overturned upper main plane; the lower plane had been +flung some few feet away with the engine and tanks under it. +Rolls was instantaneously killed by concussion of the brain. + +Antithesis to the tragedy was Audemars on his Demoiselle, which +was named 'The Infuriated Grasshopper.' Concerning this, it was +recorded at the time that 'Nothing so excruciatingly funny as +the action of this machine has ever been seen at any aviation +ground. The little two-cylinder engine pops away with a sound +like the frantic drawing of ginger beer corks; the machine +scutters along the ground with its tail well up; then down comes +the tail suddenly and seems to slap the ground while the front +jumps up, and all the spectators rock with laughter. The whole +attitude and the jerky action of the machine suggest a +grasshopper in a furious rage, and the impression is intensified +when it comes down, as it did twice on Wednesday, in long grass, +burying its head in the ground in its temper.'--(The Aero, July, +1910.) + +The Lanark Meeting followed in August of the same year, and with +the bare mention of this, the subject of flying meetings may he +left alone, since they became mere matters of show until there +came military competitions such as the Berlin Meeting at the end +of August, 1910, and the British War office Trials on Salisbury +Plain, when Cody won his greatest triumphs. The Berlin meeting +proved that, from the time of the construction of the first +successful German machine mentioned above, to the date of the +meeting, a good number of German aviators had qualified for +flight, but principally on Wright and Antoinette machines, though +by that time the Aviatik and Dorner German makes had taken the +air. The British War office Trials deserve separate and longer +mention. + +In 1910 in spite of official discouragement, Captain Dickson +proved the value of the aeroplane for scouting purposes by +observing movements of troops during the Military Manoeuvres on +Salisbury Plain. Lieut. Lancelot Gibbs and Robert Loraine, +the actor-aviator, also made flights over the manoeuvre area, +locating troops and in a way anticipating the formation and work +of the Royal Flying Corps by a usefulness which could not be +officially recognised. + + + +XV. THE CHANNEL CROSSING + +It may be said that Louis Bleriot was responsible for the second +great landmark in the history of successful flight. The day when +the brothers Wright succeeded in accomplishing power-driven +flight ranks as the first of these landmarks. Ader may or may +not have left the ground, but the wreckage of his 'Avion' at the +end of his experiment places his doubtful success in a different +category from that of the brothers Wright and leaves them the +first definite conquerors, just as Bleriot ranks as first +definite conqueror of the English Channel by air. + +In a way, Louis Bleriot ranks before Farman in point of time; +his first flapping-wing model was built as early as 1900, and +Voisin flew a biplane glider of his on the Seine in the very +early experimental days. Bleriot's first four machines were +biplanes, and his fifth, a monoplane, was wrecked almost +immediately after its construction. Bleriot had studied +Langley's work to a certain extent, and his sixth construction +was a double monoplane based on the Langley principle. A month +after he had wrecked this without damaging himself-- for Bleriot +had as many miraculous escapes as any of the other fliers-he +brought out number seven, a fairly average monoplane. It was in +December of 1907 after a series of flights that he wrecked this +machine, and on its successor, in July of 1908, he made a +flight of over 8 minutes. Sundry flights, more or less +successful, including the first cross-country flight from Toury +to Artenay, kept him busy up to the beginning of November, 1908, +when the wreckage in a fog of the machine he was flying sent him +to the building of 'number eleven,' the famous cross-channel +aeroplane. + +Number eleven was shown at the French Aero Show in the Grand +Palais and was given its first trials on the 18th January, 1909. +It was first fitted with a R.E.P. motor and had a lifting area +of 120 square feet, which was later increased to 150 square +feet. The framework was of oak and poplar spliced and +reinforced with piano wire; the weight of the machine was 47 +lbs. and the undercarriage weight a further 60 lbs., this +consisting of rubber cord shock absorbers mounted on two wheels. +The R.E.P. motor was found unsatisfactory, and a three-cylinder +Anzani of 105 mm. bore and 120 mm. stroke replaced it. An +accident seriously damaged the machine on June 2nd, but Bleriot +repaired it and tested it at Issy, where between June 19th and +June 23rd he accomplished flights of 8, 12, 15, 16, and 36 +minutes. On July 4th he made a 50-minute flight and on the 13th +flew from Etampes to Chevilly. + +A few further details of construction may be given: the wings +themselves and an elevator at the tail controlled the rate of +ascent and descent, while a rudder was also fitted at the tail. +The steering lever, working on a universally jointed +shaft--forerunner of the modern joystick--controlled both the +rudder and the wings, while a pedal actuated the elevator. The +engine drove a two-bladed tractor screw of 6 feet 7 inches +diameter, and the angle of incidence of the wings was 20 +degrees. Timed at Issy, the speed of the machine was given as 36 +miles an hour, and as Bleriot accomplished the Channel flight of +20 miles in 37 minutes, he probably had a slight following wind. + +The Daily Mail had offered a prize of L1,000 for the first +Cross-Channel flight, and Hubert Latham set his mind on winning +it. He put up a shelter on the French coast at Sangatte, +half-way between Calais and Cape Blanc Nez. From here he made +his first attempt to fly to England on Monday the 19th of July. +He soared to a fair height, circling, and reached an estimated +height of about 900 feet as he came over the water with every +appearance of capturing the Cross-Channel prize. The luck which +dogged his career throughout was against him, for, after he had +covered some 8 miles, his engine stopped and he came down to the +water in a series of long glides. It was discovered afterward +that a small piece of wire had worked its way into a vital part +of the engine to rob Latham of the honour he coveted. The tug +that came to his rescue found him seated on the fuselage of his +Antoinette, smoking a cigarette and waiting for a boat to take +him to the tug. It may be remarked that Latham merely assumed +his Antoinette would float in case he failed to make the English +coast; he had no actual proof. + +Bleriot immediately entered his machine for the prize and took +up his quarters at Barraques. On Sunday, July 25th, 1909, +shortly after 4 a.m., Bleriot had his machine taken out from its +shelter and prepared for flight. He had been recently injured +in a petrol explosion and hobbled out on crutches to make his +cross-Channel attempt; he made two great circles in the air to +try the machine, and then alighted. 'In ten minutes I start +for England,' he declared, and at 4.35 the motor was started up. +After a run of 100 yards, the machine rose in the air and got a +height of about 100 feet over the land, then wheeling sharply +seaward and heading for Dover. + +Bleriot had no means of telling direction, and any change of +wind might have driven him out over the North Sea, to be lost, +as were Cecil Grace and Hamel later on. Luck was with him, +however, and at 5.12 a.m. of that July Sunday, he made his +landing in the North Fall meadow, just behind Dover Castle. +Twenty minutes out from the French coast, he lost sight of the +destroyer which was patrolling the Channel, and at the same time +he was out of sight of land without compass or any other means +of ascertaining his direction. Sighting the English coast, he +found that he had gone too far to the east, for the wind +increased in strength throughout the flight, this to such an +extent as almost to turn the machine round when he came over +English soil. Profiting by Latham's experience, Bleriot had +fitted an inflated rubber cylinder a foot in diameter by 5 feet +in length along the middle of his fuselage, to render floating a +certainty in case he had to alight on the water. + +Latham in his camp at Sangatte had been allowed to sleep through +the calm of the early morning through a mistake on the part of a +friend, and when his machine was turned out--in order that he +might emulate Bleriot, although he no longer hoped to make the +first flight, it took so long to get the machine ready and +dragged up to its starting-point that there was a 25 mile an +hour wind by the time everything was in readiness. Latham was +anxious to make the start in spite of the wind, but the +Directors of the Antoinette Company refused permission. It was +not until two days later that the weather again became +favourable, and then with a fresh machine, since the one on +which he made his first attempt had been very badly damaged in +being towed ashore, he made a circular trial flight of about 5 +miles. In landing from this, a side gust of wind drove the nose +of the machine against a small hillock, damaging both propeller +blades and chassis, and it was not until evening that the damage +was repaired. + +French torpedo boats were set to mark the route, and Latham set +out on his second attempt at six o'clock. Flying at a height of +200 feet, he headed over the torpedo boats for Dover and seemed +certain of making the English coast, but a mile and a half out +from Dover his engine failed him again, and he dropped to the +water to be picked up by the steam pinnace of an English warship +and put aboard the French destroyer Escopette. + +There is little to choose between the two aviators for courage +in attempting what would have been considered a foolhardy feat a +year or two before. Bleriot's state, with an abscess in the +burnt foot which had to control the elevator of his machine, +renders his success all the more remarkable. His machine was +exhibited in London for a time, and was afterwards placed in the +Conservatoire des Arts et Metiers, while a memorial in stone, +copying his monoplane in form, was let into the turf at the +point where he landed. + +The second Channel crossing was not made until 1910, a year of +new records. The altitude record had been lifted to over 10,000 +feet, the duration record to 8 hours 12 minutes, and the +distance for a single flight to 365 miles, while a speed of over +65 miles an hour had been achieved, when Jacques de Lesseps, son +of the famous engineer of Suez Canal and Panama fame, crossed +from France to England on a Bleriot monoplane. By this time +flying had dropped so far from the marvellous that this second +conquest of the Channel aroused but slight public interest in +comparison with Bleriot's feat. + +The total weight of Bleriot's machine in Cross Channel trim was +660 lbs., including the pilot and sufficient petrol for a three +hours' run; at a speed of 37 miles an hour, it was capable of +carrying about 5 lbs. per square foot of lifting surface. It +was the three-cylinder 25 horse-power Anzani motor which drove +the machine for the flight. Shortly after the flight had been +accomplished, it was announced that the Bleriot firm would +construct similar machines for sale at L400 apiece--a good +commentary on the prices of those days. + +On June the 2nd, 1910, the third Channel crossing was made by C. +S. Rolls, who flew from Dover, got himself officially observed +over French soil at Barraques, and then flew back without +landing. He was the first to cross from the British side of the +Channel and also was the first aviator who made the double +journey. By that time, however, distance flights had so far +increased as to reduce the value of the feat, and thenceforth +the Channel crossing was no exceptional matter. The honour, +second only to that of the Wright Brothers, remains with Bleriot. + + + +XVI. LONDON TO MANCHESTER + +The last of the great contests to arouse public enthusiasm was +the London to Manchester Flight of 1910. As far back as 1906, +the Daily Mail had offered a prize of L10,000 to the first +aviator who should accomplish this journey, and, for a long time, +the offer was regarded as a perfectly safe one for any person or +paper to make--it brought forth far more ridicule than belief. +Punch offered a similar sum to the first man who should swim the +Atlantic and also for the first flight to Mars and back within a +week, but in the spring of 1910 Claude Grahame White and Paulhan, +the famous French pilot, entered for the 183 mile run on which +the prize depended. Both these competitors flew the Farman +biplane with the 50 horse-power Gnome motor as propulsive power. +Grahame White surveyed the ground along the route, and the L. & +N. W. Railway Company, at his request, whitewashed the sleepers +for 100 yards on the north side of all junctions to give him his +direction on the course. The machine was run out on to the +starting ground at Park Royal and set going at 5.19 a.m. on April +23rd. After a run of 100 yards, the machine went up over +Wormwood Scrubs on its journey to Normandy, near Hillmorten, +which was the first arranged stopping place en route; Grahame +White landed here in good trim at 7.20 a.m., having covered 75 +miles and made a world's record cross country flight. At 8.15 he +set off again to come down at Whittington, four miles short of +Lichfield, at about 9.20, with his machine in good order except +for a cracked landing skid. Twice, on this second stage of the +journey, he had been caught by gusts of wind which turned the +machine fully round toward London, and, when over a wood near +Tamworth, the engine stopped through a defect in the balance +springs of two exhaust valves; although it started up again +after a 100 foot glide, it did not give enough power to give him +safety in the gale he was facing. The rising wind kept him on +the ground throughout the day, and, though he hoped for better +weather, the gale kept up until the Sunday evening. The men in +charge of the machine during its halt had attempted to hold the +machine down instead of anchoring it with stakes and ropes, and, +in consequence of this, the wind blew the machine over on its +back, breaking the upper planes and the tail. Grahame White had +to return to London, while the damaged machine was prepared for +a second flight. The conditions of the competition enacted that +the full journey should be completed within 24 hours, which made +return to the starting ground inevitable. + +Louis Paulhan, who had just arrived with his Farman machine, +immediately got it unpacked and put together in order to be +ready to make his attempt for the prize as soon as the weather +conditions should admit. At 5.31 p.m., on April 27th, he went +up from Hendon and had travelled 50 miles when Grahame White, +informed of his rival's start, set out to overtake him. Before +nightfall Paulhan landed at Lichfield, 117 miles from London, +while Grahame White had to come down at Roden, only 60 miles out. +The English aviator's chance was not so small as it seemed, for, +as Latham had found in his cross-Channel attempts, engine failure +was more the rule than the exception, and a very little thing +might reverse the relative positions. + +A special train accompanied Paulhan along the North-Western +route, conveying Madame Paulhan, Henry Farman, and the mechanics +who fitted the Farman biplane together. Paulhan himself, who +had flown at a height of 1,000 feet, spent the night at +Lichfield, starting again at 4.9 a.m. On the 28th, passing +Stafford at 4.45, Crewe at 5.20, and landing at Burnage, near +Didsbury, at 5.32, having had a clean run. + +Meanwhile, Grahame White had made a most heroic attempt to beat +his rival. An hour before dawn on the 28th, he went to the +small field in which his machine had landed, and in the darkness +managed to make an ascent from ground which made starting +difficult even in daylight. Purely by instinct and his +recollection of the aspect of things the night before, he had to +clear telegraph wires and a railway bridge, neither of which he +could possibly see at that hour. His engine, too, was +faltering, and it was obvious to those who witnessed his start +that its note was far from perfect. + +At 3.50 he was over Nuneaton and making good progress; between +Atherstone and Lichfield the wind caught him and the engine +failed more and more, until at 4.13 in the morning he was forced +to come to earth, having covered 6 miles less distance than in +his first attempt. It was purely a case of engine failure, for, +with full power, he would have passed over Paulhan just as the +latter was preparing for the restart. Taking into consideration +the two machines, there is little doubt that Grahame White +showed the greater flying skill, although he lost the prize. +After landing and hearing of Paulhan's victory, on which he +wired congratulations, he made up his mind to fly to Manchester +within the 24 hours. He started at 5 o'clock in the afternoon +from Polesworth, his landing place, but was forced to land at +5.30 at Whittington, where he had landed on the previous +Saturday. The wind, which had forced his descent, fell again +and permitted of starting once more; on this third stage he +reached Lichfield, only to make his final landing at 7.15 p.m., +near the Trent Valley station. The defective running of the +Gnome engine prevented his completing the course, and his Farman +machine had to be brought back to London by rail. + +The presentation of the prize to Paulhan was made the occasion +for the announcement of a further competition, consisting of a +1,000 mile flight round a part of Great Britain. In this, +nineteen competitors started, and only four finished; the end of +the race was a great fight between Beaumont and Vedrines, both +of whom scorned weather conditions in their determination to +win. Beaumont made the distance in a flying time of 22 hours 28 +minutes 19 seconds, and Vedrines covered the journey in a little +over 23 1/2 hours. Valentine came third on a Deperdussin +monoplane and S. F. Cody on his Cathedral biplane was fourth. +This was in 1911, and by that time heavier-than-air flight had +so far advanced that some pilots had had war experience in the +Italian campaign in Tripoli, while long cross-country flights +were an everyday event, and bad weather no longer counted. + + + +XVII. A SUMMARY, TO 1911 + +There is so much overlapping in the crowded story of the first +years of successful power-driven flight that at this point it is +advisable to make a concise chronological survey of the chief +events of the period of early development, although much of this +is of necessity recapitulation. The story begins, of course, +with Orville Wright's first flight of 852 feet at Kitty Hawk on +December 19th, 1903. The next event of note was Wright's flight +of 11.12 miles in 18 minutes 9 seconds at Dayton, Ohio, on +September 26th, 1905, this being the first officially recorded +flight. On October 4th of the same year, Wright flew 20.75 miles +in 33 minutes 17 seconds, this being the first flight of over 20 +miles ever made. Then on September 14th 1906, Alberto +Santos-Dumont made a flight of eight seconds on the second +heavier-than-air machine he had constructed. It was a big +box-kite-like machine; this was the second power-driven aeroplane +in Europe to fly, for although Santos-Dumont's first machine +produced in 1905 was reckoned an unsuccessful design, it had +actually got off the ground for brief periods. Louis Bleriot +came into the ring on April 5th, 1907, with a first flight of 6 +seconds on a Bleriot monoplane, his eighth but first successful +construction. + +Henry Farman made his first appearance in the history of aviation +with a flight of 935 feet on a Voisin biplane on October 15th +1907. On October 25th, in a flight of 2,530 feet, he made the +first recorded turn in the air, and on March 29th, 1908, carrying +Leon Delagrange on a Voisin biplane, he made the first passenger +flight. On April 10th of this year, Delagrange, in flying 1 1/2 +miles, made the first flight in Europe exceeding a mile in +distance. He improved on this by flying 10 1/2 miles at Milan on +June 22nd, while on July 8th, at Turin, he took up Madame +Peltier, the first woman to make an aeroplane flight. + +Wilbur Wright, coming over to Europe, made his first appearance +on the Continent with a flight of 1 3/4 minutes at Hunaudieres, +France, on August 8th, 1908. On September 6th, at Chalons, he +flew for 1 hour 4 minutes 26 seconds with a passenger, this +being the first flight in which an hour in the air was exceeded +with a passenger on board. + +on September 12th 1908, Orville Wright, flying at Fort Meyer, +U.S.A., with Lieut. Selfridge as passenger, crashed his +machine, suffering severe injuries, while Selfridge was killed. +This was the first aeroplane fatality. On October 30th, 1908, +Farman made the first cross-country flight, covering the +distance of 17 miles between Bouy and Rheims. The next day, +Louis Bleriot, in flying from Toury to Artenay, made two +landings en route, this being the first cross-country flight +with landings. On the last day of the year, Wilbur Wright won +the Michelin Cup at Auvours with a flight of 90 miles, which, +lasting 2 hours 20 minutes 23 seconds, exceeded 2 hours in the +air for the first time. + +On January 2nd, 1909, S. F. Cody opened the New Year by making +the first observed flight at Farnborough on a British Army +aeroplane. It was not until July 18th of 1909 that the first +European height record deserving of mention was put up by +Paulhan, who achieved a height of 450 feet on a Voisin +biplane. This preceded Latham's first attempt to fly the +Channel by two days, and five days later, on the 25th of the +month, Bleriot made the first Channel crossing. The Rheims +Meeting followed on August 22nd, and it was a great day for +aviation when nine machines were seen in the air at once. It +was here that Farman, with a 118 mile flight, first exceeded +the hundred miles, and Latham raised the height record +officially to 500 feet, though actually he claimed to have +reached 1,200 feet. On September 8th, Cody, flying from +Aldershot, made a 40 mile journey, setting up a new +cross-country record. On October 19th the Comte de Lambert +flew from Juvisy to Paris, rounded the Eiffel Tower and flew +back. J. T. C. Moore-Brabazon made the first circular mile +flight by a British aviator on an all-British machine in Great +Britain, on October 30th, flying a Short biplane with a Green +engine. Paulhan, flying at Brooklands on November 2nd, +accomplished 96 miles in 2 hours 48 minutes, creating a British +distance record; on the following day, Henry Farman made a +flight of 150 miles in 4 hours 22 minutes at Mourmelon, and on +the 5th of the month, Paulhan, flying a Farman biplane, made a +world's height record of 977 feet. This, however, was not to +stand long, for Latham got up to 1,560 feet on an Antoinette at +Mourmelon on December 1st. December 31st witnessed the first +flight in Ireland, made by H. Ferguson on a monoplane which he +himself had constructed at Downshire Park, Lisburn. + +These, thus briefly summarised, are the principal events up to +the end of 1909. 1910 opened with tragedy, for on January 4th +Leon Delagrange, one of the greatest pilots of his time, was +killed while flying at Pau. The machine was the Bleriot XI which +Delagrange had used at the Doncaster meeting, and to which +Delagrange had fitted a 50 horse-power Gnome engine, increasing +the speed of the machine from its original 30 to 45 miles per +hour. With the Rotary Gnome engine there was of necessity a +certain gyroscopic effect, the strain of which proved too much +for the machine. Delagrange had come to assist in the +inauguration of the Croix d'Hins aerodrome, and had twice lapped +the course at a height of about 60 feet. At the beginning of +the third lap, the strain of the Gnome engine became too great +for the machine; one wing collapsed as if the stay wires had +broken, and the whole machine turned over and fell, killing +Delagrange. + +On January 7th Latham, flying at Mourmelon, first made the +vertical kilometre and dedicated the record to Delagrange, this +being the day of his friend's funeral. The record was +thoroughly authenticated by a large registering barometer which +Latham carried, certified by the officials of the French Aero +Club. Three days later Paulhan, who was at Los Angeles, +California, raised the height record to 4,146 feet. + +On January 25th the Brussels Exhibition opened, when the +Antoinette monoplane, the Gaffaux and Hanriot monoplanes, +together with the d'Hespel aeroplane, were shown; there were +also the dirigible Belgica and a number of interesting aero +engines, including a German airship engine and a four-cylinder +50 horse-power Miesse, this last air-cooled by means of 22 +fans driving a current of air through air jackets surrounding +fluted cylinders. + +On April 2nd Hubert Le Blon, flying a Bleriot with an Anzani +engine, was killed while flying over the water. His machine was +flying quite steadily, when it suddenly heeled over and came +down sideways into the sea; the motor continued running for some +seconds and the whole machine was drawn under water. When boats +reached the spot, Le Blon was found lying back in the driving +seat floating just below the surface. He had done good flying +at Doncaster, and at Heliopolis had broken the world's speed +records for 5 and 10 kilometres. The accident was attributed +to fracture of one of the wing stay wires when running into a +gust of wind. + +The next notable event was Paulhan's London-Manchester flight, +of which full details have already been given. In May Captain +Bertram Dickson, flying at the Tours meeting, beat all the +Continental fliers whom he encountered, including Chavez, the +Peruvian, who later made the first crossing of the Alps. +Dickson was the first British winner of international aviation +prizes. + +C. S. Rolls, of whom full details have already been given, was +killed at Bournemouth on July 12th, being the first British +aviator of note to be killed in an aeroplane accident. His +return trip across the Channel had taken place on June 2nd. +Chavez, who was rapidly leaping into fame, as a pilot, raised +the British height record to 5,750 feet while flying at +Blackpool on August 3rd. On the 11th of that month, Armstrong +Drexel, flying a Bleriot, made a world's height record of 6,745 +feet. + +It was in 1910 that the British War office first began fully to +realise that there might be military possibilities in +heavier-than-air flying. C. S. Rolls had placed a Wright +biplane at the disposal of the military authorities, and Cody, +as already recorded, had been experimenting with a biplane type +of his own for some long period. Such development as was +achieved was mainly due to the enterprise and energy of Colonel +J. E. Capper, C.B., appointed to the superintendency of the +Balloon Factory and Balloon School at Farnborough in 1906. +Colonel Capper's retirement in 1910 brought (then) Mr Mervyn +O'Gorman to command, and by that time the series of successes of +the Cody biplane, together with the proved efficiency of the +aeroplane in various civilian meetings, had convinced the +British military authorities that the mastery of the air did not +lie altogether with dirigible airships, and it may be said that +in 1910 the British War office first began seriously to consider +the possibilities of the aeroplane, though two years more were +to elapse before the formation of the Royal Flying Corps marked +full realisation of its value. + +A triumph and a tragedy were combined in September of 1910. On +the 23rd of the month, Georges Chavez set out to fly across the +Alps on a Bleriot monoplane. Prizes had been offered by the +Milan Aviation Committee for a flight from Brigue in Switzerland +over the Simplon Pass to Milan, a distance of 94 miles with a +minimum height of 6,600 feet above sea level. Chavez started at +1.30 p.m. On the 23rd, and 41 minutes later he reached +Domodossola, 25 miles distant. Here he descended, numbed with +the cold of the journey; it was said that the wings of his +machine collapsed when about 30 feet from the ground, but +however this may have been, he smashed the machine on landing, +and broke both legs, in addition to sustaining other serious +injuries. He lay in hospital until the 27th September, when he +died, having given his life to the conquest of the Alps. His +death in the moment of success was as great a tragedy as were +those of Pilcher and Lilienthal. + +The day after Chavez's death, Maurice Tabuteau flew across the +Pyrenees, landing in the square at Biarritz. On December 30th, +Tabuteau made a flight of 365 miles in 7 hours 48 minutes. +Farman, on December 18th, had flown for over 8 hours, but his +total distance was only 282 miles. The autumn of this year was +also noteworthy for the fact that aeroplanes were first +successfully used in the French Military Manoeuvres. The +British War Office, by the end of the year, had bought two +machines, a military type Farman and a Paulhan, ignoring British +experimenters and aeroplane builders of proved reliability. +These machines, added to an old Bleriot two-seater, appear to +have constituted the British aeroplane fleet of the period. + +There were by this time three main centres of aviation in +England, apart from Cody, alone on Laffan's Plain. These three +were Brooklands, Hendon, and the Isle of Sheppey, and of the +three Brooklands was chief. Here such men as Graham Gilmour, +Rippen, Leake, Wickham, and Thomas persistently experimented. +Hendon had its own little group, and Shellbeach, Isle of +Sheppey, held such giants of those days as C. S. Rolls and +Moore Brabazon, together with Cecil Grace and Rawlinson. One or +other, and sometimes all of these were deserted on the occasion +of some meeting or other, but they were the points where the +spade work was done, Brooklands taking chief place. 'If you want +the early history of flying in England, it is there,' one of the +early school remarked, pointing over toward Brooklands course. + +1911 inaugurated a new series of records of varying character. +On the 17th January, E. B. Ely, an American, flew from the shore +of San Francisco to the U.S. cruiser Pennsylvania, landing on the +cruiser, and then flew back to the shore. The British military +designing of aeroplanes had been taken up at Farnborough by G. H. +de Havilland, who by the end of January was flying a machine of +his own design, when he narrowly escaped becoming a casualty +through collision with an obstacle on the ground, which swept the +undercarriage from his machine. + +A list of certified pilots of the countries of the world was +issued early in 1911, showing certificates granted up to the +end of 1910. France led the way easily with 353 pilots; England +came next with 57, and Germany next with 46; Italy owned 32, +Belgium 27, America 26, and Austria 19; Holland and Switzerland +had 6 aviators apiece, while Denmark followed with 3, Spain with +2, and Sweden with 1. The first certificate in England was that +of J. T. C. Moore-Brabazon, while Louis Bleriot was first on +the French list and Glenn Curtiss, first holder of an American +certificate, also held the second French brevet. + +On the 7th March, Eugene Renaux won the Michelin Grand Prize by +flying from the French Aero Club ground at St Cloud and landing +on the Puy de Dome. The landing, which was one of the +conditions of the prize, was one of the most dangerous +conditions ever attached to a competition; it involved dropping +on to a little plateau 150 yards square, with a possibility of +either smashing the machine against the face of the mountain, or +diving over the edge of the plateau into the gulf beneath. The +length of the journey was slightly over 200 miles and the height +of the landing point 1,465 metres, or roughly 4,500 feet above +sea-level. Renaux carried a passenger, Doctor Senoucque, a +member of Charcot's South Polar Expedition. + +The 1911 Aero Exhibition held at Olympia bore witness to the +enormous strides made in construction, more especially by +British designers, between 1908 and the opening of the Show. +The Bristol Firm showed three machines, including a military +biplane, and the first British built biplane with tractor screw. +The Cody biplane, with its enormous size rendering it a +prominent feature of the show, was exhibited. Its designer +anticipated later engines by expressing his desire for a motor +of 150 horse-power, which in his opinion was necessary to get +the best results from the machine. The then famous Dunne +monoplane was exhibited at this show, its planes being V-shaped +in plan, with apex leading. It embodied the results of very +lengthy experiments carried out both with gliders and +power-driven machines by Colonel Capper, Lieut. Gibbs, and +Lieut. Dunne, and constituted the longest step so far taken in +the direction of inherent stability. + +Such forerunners of the notable planes of the war period as the +Martin Handasyde, the Nieuport, Sopwith, Bristol, and Farman +machines, were features of the show; the Handley-Page monoplane, +with a span of 32 feet over all, a length of 22 feet, and a +weight of 422 lbs., bore no relation at all to the twin-engined +giant which later made this firm famous. In the matter of +engines, the principal survivals to the present day, of which +this show held specimens, were the Gnome, Green, Renault +air-cooled, Mercedes four-cylinder dirigible engine of 115 +horse-power, and 120 horsepower Wolseley of eight cylinders for +use with dirigibles. + +On April 12th, of 1911, Paprier, instructor at the Bleriot +school at Hendon, made the first non-stop flight between London +and Paris. He left the aerodrome at 1.37 p.m., and arrived at +Issy-les-Moulineaux at 5.33 p.m., thus travelling 250 miles in a +little under 4 hours. He followed the railway route practically +throughout, crossing from Dover to nearly opposite Calais, +keeping along the coast to Boulogne, and then following the Nord +Railway to Amiens, Beauvais, and finally Paris. + +In May, the Paris-Madrid race took place; Vedrines, flying a +Morane biplane, carried off the prize by first completing the +distance of 732 miles. The Paris-Rome race of 916 miles was won +in the same month by Beaumont, flying a Bleriot monoplane. In +July, Koenig won the German National Circuit race of 1,168 miles +on an Albatross biplane. This was practically simultaneous with +the Circuit of Britain won by Beaumont, who covered 1,010 miles +on a Bleriot monoplane, having already won the +Paris-Brussels-London-Paris Circuit of 1,080 miles, this also on +a Bleriot. It was in August that a new world's height record of +11,152 feet was set up by Captain Felix at Etampes, while +on the 7th of the month Renaux flew nearly 600 miles on a +Maurice Farman machine in 12 hours. Cody and Valentine were +keeping interest alive in the Circuit of Britain race, although +this had long been won, by determinedly plodding on at finishing +the course. + +On September 9th, the first aerial post was tried between Hendon +and Windsor, as an experiment in sending mails by aeroplane. +Gustave Hamel flew from Hendon to Windsor and back in a strong +wind. A few days later, Hamel went on strike, refusing to carry +further mails unless the promoters of the Aerial Postal Service +agreed to pay compensation to Hubert, who fractured both his legs +on the 11th of the month while engaged in aero postal work. The +strike ended on September 25th, when Hamel resumed mail-carrying +in consequence of the capitulation of the Postmaster-General, who +agreed to set aside L500 as compensation to Hubert. + +September also witnessed the completion in America of a flight +across the Continent, a distance of 2,600 miles. The only +competitor who completed the full distance was C. P. Rogers, +who was disqualified through failing to comply with the time +limit. Rogers needed so many replacements to his machine on the +journey that, expressing it in American fashion, he arrived with +practically a dfferent aeroplane from that with which he +started. + +With regard to the aerial postal service, analysis of the matter +carried and the cost of the service seemed to show that with a +special charge of one shilling for letters and sixpence for post +cards, the revenue just balanced the expenditure. It was not +possible to keep to the time-table as, although the trials were +made in the most favourable season of the year, aviation was not +sufficiently advanced to admit of facing all weathers and +complying with time-table regulations. + +French military aeroplane trials took place at Rheims in +October, the noteworthy machines being Antoinette, Farman, +Nieuport, and Deperdussin. The tests showed the Nieuport +monoplane with Gnome motor as first in position; the Breguet +biplane was second, and the Deperdussin monoplanes third. The +first five machines in order of merit were all engined with the +Gnome motor. + +The records quoted for 1911 form the best evidence that can +be given of advance in design and performance during the year. +It will be seen that the days of the giants were over; design +was becoming more and more standardised and aviation not so much +a matter of individual courage and even daring, as of the +reliability of the machine and its engine. This was the first +year in which the twin-engined aeroplane made its appearance, +and it was the year, too, in which flying may be said to have +grown so common that the 'meetings' which began with Rheims were +hardly worth holding, owing to the fact that increase in height +and distance flown rendered it no longer necessary for a +would-be spectator of a flight to pay half a crown and enter an +enclosure. Henceforth, flying as a spectacle was very little to +be considered; its commercial aspects were talked of, and to a +very slight degree exploited, but, more and more, the fact that +the aeroplane was primarily an engine of war, and the growing +German menace against the peace of the world combined to point +the way of speediest development, and the arrangements for the +British Military Trials to be held in August, 1912, showed that +even the British War office was waking up to the potentialities +of this new engine of war. + + + +XVIII. A SUMMARY, TO 1914 + +Consideration of the events in the years immediately preceding +the War must be limited to as brief a summary as possible, this +not only because the full history of flying achievements is +beyond the compass of any single book, but also because, viewing +the matter in perspective, the years 1903-1911 show up as far +more important as regards both design and performance. From +1912 to August of 1914, the development of aeronautics was +hindered by the fact that it had not progressed far enough to +form a real commercial asset in any country. The meetings which +drew vast concourses of people to such places as Rheims and +Bournemouth may have been financial successes at first, but, as +flying grew more common and distances and heights extended, a +great many people found it other than worth while to pay for +admission to an aerodrome. The business of taking up passengers +for pleasure flights was not financially successful, and, +although schemes for commercial routes were talked of, the +aeroplane was not sufficiently advanced to warrant the +investment of hard cash in any of these projects. There was a +deadlock; further development was necessary in order to secure +financial aid, and at the same time financial aid was necessary +in order to secure further development. Consequently, neither +was forthcoming. + +This is viewing the matter in a broad and general sense; there +were firms, especially in France, but also in England and +America, which looked confidently for the great days of flying to +arrive, and regarded their sunk capital as investment which would +eventually bring its due return. But when one looks back on +those years, the firms in question stand out as exceptions to the +general run of people, who regarded aeronautics as something +extremely scientific, exceedingly dangerous, and very expensive. +The very fame that was attained by such pilots as became +casualties conduced to the advertisement of every death, and the +dangers attendant on the use of heavier-than-air machines became +greatly exaggerated; considering the matter as one of number of +miles flown, even in the early days, flying exacted no more toll +in human life than did railways or road motors in the early +stages of their development. But to take one instance, when C. +S. Rolls was killed at Bournemouth by reason of a faulty +tail-plane, the fact was shouted to the whole world with almost +as much vehemence as characterised the announcement of the +Titanic sinking in mid-Atlantic. + +Even in 1911 the deadlock was apparent; meetings were falling +off in attendance, and consequently in financial benefit to the +promoters; there remained, however, the knowledge--for it was +proved past question--that the aeroplane in its then stage of +development was a necessity to every army of the world. France +had shown this by the more than interest taken by the French +Government in what had developed into an Air Section of the +French army; Germany, of course, was hypnotised by Count +Zeppelin and his dirigibles, to say nothing of the Parsevals +which had been proved useful military accessories; in spite of +this, it was realised in Germany that the aeroplane also had its +place in military affairs. England came into the field with the +military aeroplane trials of August 1st to 15th, 1912, barely two +months after the founding of the Royal Flying Corps. + +When the R.F.C. was founded--and in fact up to two years after +its founding--in no country were the full military +potentialities of the aeroplane realised; it was regarded as an +accessory to cavalry for scouting more than as an independent +arm; the possibilities of bombing were very vaguely considered, +and the fact that it might be possible to shoot from an +aeroplane was hardly considered at all. The conditions of the +British Military Trials of 1912 gave to the War office the +option of purchasing for L1,000 any machine that might be +awarded a prize. Machines were required, among other things, to +carry a useful load of 350 lbs. in addition to equipment, with +fuel and oil for 4 1/2-hours; thus loaded, they were required to +fly for 3 hours, attaining an altitude of 4,500 feet, maintaining +a height of 1,500 feet for 1 hour, and climbing 1,000 feet from +the ground at a rate of 200 feet per minute, 'although 300 feet +per minute is desirable.' They had to attain a speed of not less +than 55 miles per hour in a calm, and be able to plane down to +the ground in a calm from not more than 1,000 feet with engine +stopped, traversing 6,000 feet horizontal distance. For those +days, the landing demands were rather exacting; the machine +should be able to rise without damage from long grass, clover, or +harrowed land, in 100 yards in a calm, and should be able to land +without damage on any cultivated ground, including rough ploughed +land, and, when landing on smooth turf in a calm, be able to pull +up within 75 yards of the point of first touching the ground. It +was required that pilot and observer should have as open a view +as possible to front and flanks, and they should be so shielded +from the wind as to be able to communicate with each other. +These are the main provisions out of the set of conditions laid +down for competitors, but a considerable amount of leniency was +shown by the authorities in the competition, who obviously wished +to try out every machine entered and see what were its +capabilities. + +The beginning of the competition consisted in assembling the +machines against time from road trim to flying trim. Cody's +machine, which was the only one to be delivered by air, took 1 +hour and 35 minutes to assemble; the best assembling time was +that of the Avro, which was got into flying trim in 14 minutes 30 +seconds. This machine came to grief with Lieut. Parke as pilot, +on the 7th, through landing at very high speed on very bad +ground; a securing wire of the under-carriage broke in the +landing, throwing the machine forward on to its nose and then +over on its back. Parke was uninjured, fortunately; the damaged +machine was sent off to Manchester for repair and was back again +on the 16th of August. + +It is to be noted that by this time the Royal Aircraft Factory +was building aeroplanes of the B.E. and F.E. types, but at the +same time it is also to be noted that British military interest +in engines was not sufficient to bring them up to the high level +attained by the planes, and it is notorious that even the +outbreak of war found England incapable of providing a really +satisfactory aero engine. In the 1912 Trials, the only machines +which actually completed all their tests were the Cody biplane, +the French Deperdussin, the Hanriot, two Bleriots and a Maurice +Farman. The first prize of L4,000, open to all the world, went +to F. S. Cody's British-built biplane, which complied with all +the conditions of the competition and well earned its official +acknowledgment of supremacy. The machine climbed at 280 feet per +minute and reached a height of 5,000 feet, while in the landing +test, in spite of its great weight and bulk, it pulled up on +grass in 56 yards. The total weight was 2,690 lbs. when fully +loaded, and the total area of supporting surface was 500 square +feet; the motive power was supplied by a six-cylinder 120 +horsepower Austro-Daimler engine. The second prize was taken by +A. Deperdussin for the French-built Deperdussin monoplane. Cody +carried off the only prize awarded for a British-built plane, +this being the sum of L1,000, and consolation prizes of L500 each +were awarded to the British Deperdussin Company and The British +and Colonial Aeroplane Company, this latter soon to become famous +as makers of the Bristol aeroplane, of which the war honours are +still fresh in men's minds. + +While these trials were in progress Audemars accomplished the +first flight between Paris and Berlin, setting out from Issy +early in the morning of August 18th, landing at Rheims to refill +his tanks within an hour and a half, and then coming into bad +weather which forced him to land successively at Mezieres, +Laroche, Bochum, and finally nearly Gersenkirchen, where, owing +to a leaky petrol tank, the attempt to win the prize offered for +the first flight between the two capitals had to be abandoned +after 300 miles had been covered, as the time limit was +definitely exceeded. Audemars determined to get through to +Berlin, and set off at 5 in the morning of the 19th, only to be +brought down by fog; starting off again at 9.15 he landed at +Hanover, was off again at 1.35, and reached the Johannisthal +aerodrome in the suburbs of Berlin at 6.48 that evening. + +As early as 1910 the British Government possessed some ten +aeroplanes, and in 1911 the force developed into the Army Air +Battalion, with the aeroplanes under the control of Major J. H. +Fulton, R.F.A. Toward the end of 1911 the Air Battalion was +handed over to (then) Brig.-Gen. D. Henderson, Director of +Military Training. On June 6th, 1912, the Royal Flying Corps was +established with a military wing under Major F. H. Sykes and a +naval wing under Commander C. R. Samson. A joint Naval and +Military Flying School was established at Upavon with Captain +Godfrey M. Paine, R.N., as Commandant and Major Hugh Trenchard +as Assistant Commandant. The Royal Aircraft Factory brought out +the B.E. and F.E. types of biplane, admittedly superior to any +other British design of the period, and an Aircraft Inspection +Department was formed under Major J. H. Fulton. The military +wing of the R.F.C. was equipped almost entirely with machines +of Royal Aircraft Factory design, but the Navy preferred to +develop British private enterprise by buying machines from +private firms. On July 1st, 1914 the establishment of the Royal +Naval Air Service marked the definite separation of the military +and naval sides of British aviation, but the Central Flying +School at Upavon continued to train pilots for both services. + +It is difficult at this length of time, so far as the military +wing was concerned, to do full justice to the spade work done by +Major-General Sir David Henderson in the early days. Just before +war broke out, British military air strength consisted officially +of eight squadrons, each of 12 machines and 13 in reserve, with +the necessary complement of road transport. As a matter of fact, +there were three complete squadrons and a part of a fourth which +constituted the force sent to France at the outbreak of war. The +value of General Henderson's work lies in the fact that, in spite +of official stinginess and meagre supplies of every kind, he +built up a skeleton organisation so elastic and so well thought +out that it conformed to war requirements as well as even the +German plans fitted in with their aerial needs. On the 4th of +August, 1914, the nominal British air strength of the military +wing was 179 machines. Of these, 82 machines proceeded to +France, landing at Amiens and flying to Maubeuge to play their +part in the great retreat with the British Expeditionary Force, +in which they suffered heavy casualties both in personnel and +machines. The history of their exploits, however, belongs to the +War period. + +The development of the aeroplane between 1912 and 1914 can be +judged by comparison of the requirements of the British War +Office in 1912 with those laid down in an official memorandum +issued by the War Office in February, 1914. This latter +called for a light scout aeroplane, a single-seater, with fuel +capacity to admit of 300 miles range and a speed range of from +50 to 85 miles per hour. It had to be able to climb 3,500 feet +in five minutes, and the engine had to be so constructed that +the pilot could start it without assistance. At the same time, +a heavier type of machine for reconnaissance work was called +for, carrying fuel for a 200 mile flight with a speed range of +between 35 and 60 miles per hour, carrying both pilot and +observer. It was to be equipped with a wireless telegraphy set, +and be capable of landing over a 30 foot vertical obstacle and +coming to rest within a hundred yards' distance from the +obstacle in a wind of not more than 15 miles per hour. A third +requirement was a heavy type of fighting aeroplane accommodating +pilot and gunner with machine gun and ammunition, having a speed +range of between 45 and 75 miles per hour and capable of +climbing 3,500 feet in 8 minutes. It was required to carry fuel +for a 300 mile flight and to give the gunner a clear field of +fire in every direction up to 30 degrees on each side of the +line of flight. Comparison of these specifications with those +of the 1912 trials will show that although fighting, scouting, +and reconnaissance types had been defined, the development of +performance compared with the marvellous development of the +earlier years of achieved flight was small. + +Yet the records of those years show that here and there an +outstanding design was capable of great things. On the 9th +September, 1912, Vedrines, flying a Deperdussin monoplane at +Chicago, attained a speed of 105 miles an hour. On August 12th, +G. de Havilland took a passenger to a height of 10,560 feet +over Salisbury Plain, flying a B.E. biplane with a 70 +horse-power Renault engine. The work of de Havilland may be +said to have been the principal influence in British military +aeroplane design, and there is no doubt that his genius was in +great measure responsible for the excellence of the early B.E. +and F.E. types. + +on the 31st May, 1913, H. G. Hawker, flying at Brooklands, +reached a height of 11,450 feet on a Sopwith biplane engined with +an 80 horse-power Gnome engine. On June 16th, with the same type +of machine and engine, he achieved 12,900 feet. On the 2nd +October, in the same year, a Grahame White biplane with 120 +horse-power Austro-Daimler engine, piloted by Louis Noel, made a +flight of just under 20 minutes carrying 9 passengers. In France +a Nieuport monoplane piloted by G. Legagneaux attained a height +of 6,120 metres, or just over 20,070 feet, this being the world's +height record. It is worthy of note that of the world's aviation +records as passed by the International Aeronautical Federation up +to June 30th, 1914, only one, that of Noel, is credited to Great +Britain. + +Just as records were made abroad, with one exception, so were +the really efficient engines. In England there was the Green +engine, but the outbreak of war found the Royal Flying Corps +with 80 horse-power Gnomes, 70 horse-power Renaults, and one or +two Antoinette motors, but not one British, while the Royal +Naval Air Service had got 20 machines with engines of similar +origin, mainly land planes in which the wheeled undercarriages +had been replaced by floats. France led in development, and +there is no doubt that at the outbreak of war, the French +military aeroplane service was the best in the world. It was +mainly composed of Maurice Farman two-seater biplanes and +Bleriot monoplanes-- the latter type banned for a period on +account of a number of serious accidents that took place in 1912 + +America had its Army Aviation School, and employed Burgess-Wright +and Curtiss machines for the most part. In the pre-war years, +once the Wright Brothers had accomplished their task, America's +chief accomplishment consisted in the development of the 'Flying + +Boat,' alternatively named with characteristic American +clumsiness, 'The Hydro-Aeroplane.' In February of 1911, Glenn +Curtiss attached a float to a machine similar to that with which +he won the first Gordon-Bennett Air Contest and made his first +flying boat experiment. From this beginning he developed the +boat form of body which obviated the use and troubles of +floats--his hydroplane became its own float. + +Mainly owing to greater engine reliability the duration records +steadily increased. By September of 1912 Fourny, on a Maurice +Farman biplane, was able to accomplish a distance of 628 miles +without a landing, remaining in the air for 13 hours 17 minutes +and just over 57 seconds. By 1914 this was raised by the German +aviator, Landemann, to 21 hours 48 3/4 seconds. The nature of +this last record shows that the factors in such a record had +become mere engine endurance, fuel capacity, and capacity of the +pilot to withstand air conditions for a prolonged period, rather +than any exceptional flying skill. + +Let these years be judged by the records they produced, and even +then they are rather dull. The glory of achievement such as +characterised the work of the Wright Brothers, of Bleriot, and +of the giants of the early days, had passed; the splendid +courage, the patriotism and devotion of the pilots of the War +period had not yet come to being. There was progress, past +question, but it was mechanical, hardly ever inspired. The +study of climatic conditions was definitely begun and +aeronautical meteorology came to being, while another development +already noted was the fitting of wireless telegraphy to +heavier-than-air machines, as instanced in the British War +office specification of February, 1914. These, however, were +inevitable; it remained for the War to force development beyond +the inevitable, producing in five years that which under normal +circumstances might easily have occupied fifty --the aeroplane of +to-day; for, as already remarked, there was a deadlock, and any +survey that may be made of the years 1912-1914, no matter how +superficial, must take it into account with a view to retaining +correct perspective in regard to the development of the +aeroplane. + +There is one story of 1914 that must be included, however +briefly, in any record of aeronautical achievement, since it +demonstrates past question that to Professor Langley really +belongs the honour of having achieved a design which would ensure +actual flight, although the series of accidents which attended +his experiments gave to the Wright Brothers the honour of first +leaving the earth and descending without accident in a +power-driven heavier-than-air machine. In March, 1914, Glenn +Curtiss was invited to send a flying boat to Washington for the +celebration of 'Langley Day,' when he remarked, 'I would like to +put the Langley aeroplane itself in the air.' In consequence of +this remark, Secretary Walcot of the Smithsonian Institution +authorised Curtiss to re-canvas the original Langley aeroplane +and launch it either under its own power or with a more recent +engine and propeller. Curtiss completed this, and had the +machine ready on the shores of Lake Keuka, Hammondsport, N.Y., by +May. The main object of these renewed trials was to show whether +the original Langley machine was capable of sustained free flight +with a pilot, and a secondary object was to determine more fully +the advantages of the tandem monoplane type; thus the aeroplane +was first flown as nearly as possible in its original condition, +and then with such modifications as seemed desirable. The only +difference made for the first trials consisted in fitting floats +with connecting trusses; the steel main frame, wings, rudders, +engine, and propellers were substantially as they had been in +1903. The pilot had the same seat under the main frame and the +same general system of control. He could raise or lower the +craft by moving the rear rudder up and down; he could steer +right or left by moving the vertical rudder. He had no ailerons +nor wing-warping mechanism, but for lateral balance depended on +the dihedral angle of the wings and upon suitable movements of +his weight or of the vertical rudder. + +After the adjustments for actual flight had been made in the +Curtiss factory, according to the minute descriptions contained +in the Langley Memoir on Mechanical Flight, the aeroplane was +taken to the shore of Lake Keuka, beside the Curtiss hangars, +and assembled for launching. On a clear morning (May 28th) and +in a mild breeze, the craft was lifted on to the water by a +dozen men and set going, with Mr Curtiss at the steering wheel, +esconced in the little boat-shaped car under the forward part of +the frame. The four-winged craft, pointed somewhat across the +wind, went skimming over the waveless, then automatically headed +into the wind, rose in level poise, soared gracefully for 150 +feet, and landed softly on the water near the shore. Mr Curtiss +asserted that he could have flown farther, but, being unused to +the machine, imagined that the left wings had more resistance +than the right. The truth is that the aeroplane was perfectly +balanced in wing resistance, but turned on the water like a +weather vane, owing to the lateral pressure on its big rear +rudder. Hence in future experiments this rudder was made +turnable about a vertical axis, as well as about the horizontal +axis used by Langley. Henceforth the little vertical rudder +under the frame was kept fixed and inactive.[*] + +That the Langley aeroplane was subsequently fitted with an 80 +horse-power Curtiss engine and successfully flown is of little +interest in such a record as this, except for the fact that with +the weight nearly doubled by the new engine and accessories the +machine flew successfully, and demonstrated the perfection of +Langley's design by standing the strain. The point that is of +most importance is that the design itself proved a success and +fully vindicated Langley's work. At the same time, it would be +unjust to pass by the fact of the flight without according to +Curtiss due recognition of the way in which he paid tribute to +the genius of the pioneer by these experiments. + +[*] Smithsonian Publications No. 2329. + + + +XIX. THE WAR PERIOD--I + +Full record of aeronautical progress and of the accomplishments +of pilots in the years of the War would demand not merely a +volume, but a complete library, and even then it would be barely +possible to pay full tribute to the heroism of pilots of the war +period. There are names connected with that period of which the +glory will not fade, names such as Bishop, Guynemer, Boelcke, +Ball, Fonck, Immelmann, and many others that spring to mind as +one recalls the 'Aces' of the period. In addition to the +pilots, there is the stupendous development of the +machines--stupendous when the length of the period in which it +was achieved is considered. + +The fact that Germany was best prepared in the matter of +heavier-than-air service machines in spite of the German faith +in the dirigible is one more item of evidence as to who forced +hostilities. The Germans came into the field with well over 600 +aeroplanes, mainly two-seaters of standardised design, and with +factories back in the Fatherland turning out sufficient new +machines to make good the losses. There were a few +single-seater scouts built for speed, and the two-seater +machines were all fitted with cameras and bomb-dropping gear. +Manoeuvres had determined in the German mind what should be the +uses of the air fleet; there was photography of fortifications +and field works; signalling by Very lights; spotting for the +guns, and scouting for news of enemy movements. The methodical +German mind had arranged all this beforehand, but had not allowed +for the fact that opponents might take counter-measures which +would upset the over-perfect mechanism of the air service just as +effectually as the great march on Paris was countered by the +genius of Joffre. + +The French Air Force at the beginning of the War consisted of +upwards of 600 machines. These, unlike the Germans, were not +standardised, but were of many and diverse types. In order to +get replacements quickly enough, the factories had to work on +the designs they had, and thus for a long time after the +outbreak of hostilities standardisation was an impossibility. +The versatility of a Latin race in a measure compensated for +this; from the outset, the Germans tried to overwhelm the French +Air Force, but failed, since they had not the numerical +superiority, nor--this equally a determining factor--the +versatility and resource of the French pilots. They calculated +on a 50 per cent superiority to ensure success; they needed more +nearly 400 per cent, for the German fought to rule, avoiding +risks whenever possible, and definitely instructed to save both +machines and pilots wherever possible. French pilots, on the +other hand, ran all the risks there were, got news of German +movements, bombed the enemy, and rapidly worked up a very +respectable antiaircraft force which, whatever it may have +accomplished in the way of hitting German planes, got on the +German pilots' nerves. + +It has already been detailed how Britain sent over 82 planes as +its contribution to the military aerial force of 1914. These +consisted of Farman, Caudron, and Short biplanes, together with +Bleriot, Deperdussin and Nieuport monoplanes, certain R.A.F. +types, and other machines of which even the name barely survives +--the resourceful Yankee entitles them 'orphans.' It is on +record that the work of providing spares might have been rather +complicated but for the fact that there were none. + +There is no doubt that the Germans had made study of aerial +military needs just as thoroughly as they had perfected their +ground organisation. Thus there were 21 illuminated aircraft +stations in Germany before the War, the most powerful being at +Weimar, where a revolving electric flash of over 27 million +candle-power was located. Practically all German aeroplane +tests in the period immediately preceding the War were of a +military nature, and quite a number of reliability tests were +carried out just on the other side of the French frontier. +Night flying and landing were standardised items in the German +pilot's course of instruction while they were still experimental +in other countries, and a system of signals was arranged which +rendered the instructional course as perfect as might be. + +The Belgian contribution consisted of about twenty machines fit +for active service and another twenty which were more or less +useful as training machines. The material was mainly French, +and the Belgian pilots used it to good account until German +numbers swamped them. France, and to a small extent England, +kept Belgian aviators supplied with machines throughout the War. + +The Italian Air Fleet was small, and consisted of French machines +together with a percentage of planes of Italian origin, of which +the design was very much a copy of French types. It was not +until the War was nearing its end that the military and naval +services relied more on the home product than on imports. This +does not apply to engines, however, for the F.I.A.T. and S.C.A.T. + +were equal to practically any engine of Allied make, both in +design and construction. + +Russia spent vast sums in the provision of machines: the giant +Sikorsky biplane, carrying four 100 horsepower Argus motors, +was designed by a young Russian engineer in the latter part of +1913, and in its early trials it created a world's record by +carrying seven passengers for 1 hour 54 minutes. Sikorsky also +designed several smaller machines, tractor biplanes on the lines +of the British B.E. type, which were very successful. These +were the only home productions, and the imports consisted mainly +of French aeroplanes by the hundred, which got as far as the +docks and railway sidings and stayed there, while German +influence and the corruption that ruined the Russian Army helped +to lose the War. A few Russian aircraft factories were got into +operation as hostilities proceeded, but their products were +negligible, and it is not on record that Russia ever learned to +manufacture a magneto. + +The United States paid tribute to British efficiency by adopting +the British system of training for its pilots; 500 American +cadets were trained at the School of Military Aeronautics at +oxford, in order to form a nucleus for the American aviation +schools which were subsequently set up in the United States and +in France. As regards production of craft, the designing of the +Liberty engine and building of over 20,000 aeroplanes within a +year proves that America is a manufacturing country, even under +the strain of war. + +There were three years of struggle for aerial supremacy, the +combatants being England and France against Germany, and the +contest was neck and neck all the way. Germany led at the +outset with the standardised two-seater biplanes manned by +pilots and observers, whose training was superior to that +afforded by any other nation, while the machines themselves were +better equipped and fitted with accessories. All the early +German aeroplanes were designated Taube by the uninitiated, and +were formed with swept-back, curved wings very much resembling +the wings of a bird. These had obvious disadvantages, but the +standardisation of design and mass production of the German +factories kept them in the field for a considerable period, and +they flew side by side with tractor biplanes of improved design. +For a little time, the Fokker monoplane became a definite threat +both to French and British machines. It was an improvement on +the Morane French monoplane, and with a high-powered engine it +climbed quickly and flew fast, doing a good deal of damage for a +brief period of 1915. Allied design got ahead of it and finally +drove it out of the air. + +German equipment at the outset, which put the Allies at a +disadvantage, included a hand-operated magneto engine-starter +and a small independent screw which, mounted on one of the main +planes, drove the dynamo used for the wireless set. Cameras +were fitted on practically every machine; equipment included +accurate compasses and pressure petrol gauges, speed and height +recording instruments, bomb-dropping fittings and sectional +radiators which facilitated repairs and gave maximum engine +efficiency in spite of variations of temperature. As counter to +these, the Allied pilots had resource amounting to impudence. +In the early days they carried rifles and hand grenades and +automatic pistols. They loaded their machines down, often at +their own expense, with accessories and fittings until their +aeroplanes earned their title of Christmas trees. They played +with death in a way that shocked the average German pilot of the +War's early stages, declining to fight according to rule and +indulging in the individual duels of the air which the German +hated. As Sir John French put it in one of his reports, they +established a personal ascendancy over the enemy, and in this +way compensated for their inferior material. + +French diversity of design fitted in well with the initiative +and resource displayed by the French pilots. The big Caudron +type was the ideal bomber of the early days; Farman machines +were excellent for reconnaissance and artillery spotting; the +Bleriots proved excellent as fighting scouts and for aerial +photography; the Nieuports made good fighters, as did the Spads, +both being very fast craft, as were the Morane-Saulnier +monoplanes, while the big Voisin biplanes rivalled the Caudron +machines as bombers. + +The day of the Fokker ended when the British B.E.2.C. aeroplane +came to France in good quantities, and the F.E. type, together +with the De Havilland machines, rendered British aerial +superiority a certainty. Germany's best reply--this was about +1916--was the Albatross biplane, which was used by Captain Baron +von Richthofen for his famous travelling circus, manned by +German star pilots and sent to various parts of the line to +hearten up German troops and aviators after any specially bad +strafe. Then there were the Aviatik biplane and the Halberstadt +fighting scout, a cleanly built and very fast machine with a +powerful engine with which Germany tried to win back superiority +in the third year of the War, but Allied design kept about three +months ahead of that of the enemy, once the Fokker had been +mastered, and the race went on. Spads and Bristol fighters, +Sopwith scouts and F.E.'s played their part in the race, and +design was still advancing when peace came. + +The giant twin-engined Handley-Page bomber was tried out, proved +efficient, and justly considered better than anything of its +kind that had previously taken the field. Immediately after the +conclusion of its trials, a specimen of the type was delivered +intact at Lille for the Germans to copy, the innocent pilot +responsible for the delivery doing some great disservice to his +own cause. The Gotha Wagon-Fabrik Firm immediately set to work +and copied the Handley-Page design, producing the great Gotha +bombing machine which was used in all the later raids on England +as well as for night work over the Allied lines. + +How the War advanced design may be judged by comparison of the +military requirements given for the British Military Trials of +1912, with performances of 1916 and 1917, when the speed of the +faster machines had increased to over 150 miles an hour and +Allied machines engaged enemy aircraft at heights ranging up to +22,000 feet. All pre-war records of endurance, speed, and climb +went by the board, as the race for aerial superiority went on. + +Bombing brought to being a number of crude devices in the first +year of the War. Allied pilots of the very early days carried up +bombs packed in a small box and threw them over by hand, while, a +little later, the bombs were strung like apples on wings and +undercarriage, so that the pilot who did not get rid of his load +before landing risked an explosion. Then came a properly +designed carrying apparatus, crude but fairly efficient, and with +1916 development had proceeded as far as the proper bomb-racks +with releasing gear. + +Reconnaissance work developed, so that fighting machines went as +escort to observing squadrons and scouting operations were +undertaken up to 100 miles behind the enemy lines; out of this +grew the art of camouflage, when ammunition dumps were painted +to resemble herds of cows, guns were screened by foliage or +painted to merge into a ground scheme, and many other schemes +were devised to prevent aerial observation. Troops were moved by +night for the most part, owing to the keen eyes of the air +pilots and the danger of bombs, though occasionally the aviator +had his chance. There is one story concerning a British pilot +who, on returning from a reconnaissance flight, observed a +German Staff car on the road under him; he descended and bombed +and machine--gunned the car until the German General and his +chauffeur abandoned it, took to their heels, and ran like +rabbits. Later still, when Allied air superiority was assured, +there came the phase of machine-gunning bodies of enemy troops +from the air. Disregarding all antiaircraft measures, machines +would sweep down and throw battalions into panic or upset the +military traffic along a road, demoralising a battery or a +transport train and causing as much damage through congestion of +traffic as with their actual machine-gun fire. Aerial +photography, too, became a fine art; the ordinary long focus +cameras were used at the outset with automatic plate changers, +but later on photographing aeroplanes had cameras of wide angle +lens type built into the fuselage. These were very simply +operated, one lever registering the exposure and changing the +plate. In many cases, aerial photographs gave information which +the human eye had missed, and it is noteworthy that photographs +of ground showed when troops had marched over it, while the +aerial observer was quite unable to detect the marks left by +their passing. + +Some small mention must be made of seaplane activities, which, +round the European coasts involved in the War, never ceased. +The submarine campaign found in the spotting seaplane its +greatest deterrent, and it is old news now how even the deeply +submerged submarines were easily picked out for destruction from +a height and the news wirelessed from seaplane to destroyer, +while in more than one place the seaplane itself finished the +task by bomb dropping. It was a seaplane that gave Admiral +Beatty the news that the whole German Fleet was out before the +Jutland Battle, news which led to a change of plans that very +nearly brought about the destruction of Germany's naval power. +For the most part, the seaplanes of the War period were heavier +than the land machines and, in the opinion of the land pilots, +were slow and clumsy things to fly. This was inevitable, for +their work demanded more solid building and greater reliability. +To put the matter into Hibernian phrase, a forced landing at sea +is a much more serious matter than on the ground. Thus there +was need for greater engine power, bigger wingspread to support +the floats, and fuel tanks of greater capacity. The flying +boats of the later War period carried considerable crews, were +heavily armed, capable of withstanding very heavy weather, and +carried good loads of bombs on long cruises. Their work was not +all essentially seaplane work, for the R.N.A.S. was as well +known as hated over the German airship sheds in Belgium and +along the Flanders coast. As regards other theatres of War, +they rendered valuable service from the Dardanelles to the +Rufiji River, at this latter place forming a principal factor in +the destruction of the cruiser Konigsberg. Their spotting work +at the Dardanelles for the battleships was responsible for +direct hits from 15 in. guns on invisible targets at ranges of +over 12,000 yards. Seaplane pilots were bombing specialists, +including among their targets army headquarters, ammunition +dumps, railway stations, submarines and their bases, docks, +shipping in German harbours, and the German Fleet at +Wilhelmshaven. Dunkirk, a British seaplane base, was a sharp +thorn in the German side. + +Turning from consideration of the various services to the +exploits of the men composing them, it is difficult to +particularise. A certain inevitable prejudice even at this +length of time leads one to discount the valour of pilots in the +German Air Service, but the names of Boelcke, von Richthofen, +and Immelmann recur as proof of the courage that was not wanting +in the enemy ranks, while, however much we may decry the Gotha +raids over the English coast and on London, there is no doubt +that the men who undertook these raids were not deficient in the +form of bravery that is of more value than the unthinking valour +of a minute which, observed from the right quarter, wins a +military decoration. + +Yet the fact that the Allied airmen kept the air at all in the +early days proved on which side personal superiority lay, for +they were outnumbered, out-manoeuvred, and faced by better +material than any that they themselves possessed; yet they won +their fights or died. The stories of their deeds are endless; +Bishop, flying alone and meeting seven German machines and +crashing four; the battle of May 5th, 1915, when five heroes +fought and conquered twenty-seven German machines, ranging in +altitude between 12,000 and 3,000 feet, and continuing the +extraordinary struggle from five until six in the evening. +Captain Aizlewood, attacking five enemy machines with such +reckless speed that he rammed one and still reached his +aerodrome safely--these are items in a long list of feats of +which the character can only be realised when it is fully +comprehended that the British Air Service accounted for some +8,ooo enemy machines in the course of the War. Among the French +there was Captain Guynemer, who at the time of his death had +brought down fifty-four enemy machines, in addition to many +others of which the destruction could not be officially +confirmed. There was Fonck, who brought down six machines in +one day, four of them within two minutes. + +There are incredible stories, true as incredible, of shattered +men carrying on with their work in absolute disregard of +physical injury. Major Brabazon Rees, V.C., engaged a big +German battle-plane in September of 1915 and, single-handed, +forced his enemy out of action. Later in his career, with a +serious wound in the thigh from which blood was pouring, he kept +up a fight with an enemy formation until he had not a round of +ammunition left, and then returned to his aerodrome to get his +wound dressed. Lieutenants Otley and Dunning, flying in the +Balkans, engaged a couple of enemy machines and drove them off, +but not until their petrol tank had got a hole in it and Dunning +was dangerously wounded in the leg. Otley improvised a +tourniquet, passed it to Dunning, and, when the latter had +bandaged himself, changed from the observer's to the pilot's +seat, plugged the bullet hole in the tank with his thumb and +steered the machine home. + +These are incidents; the full list has not been, and can never +be recorded, but it goes to show that in the pilot of the War +period there came to being a new type of humanity, a product of +evolution which fitted a certain need. Of such was Captain +West, who, engaging hostile troops, was attacked by seven +machines. Early in the engagement, one of his legs was +partially severed by an explosive bullet and fell powerless into +the controls, rendering the machine for the time unmanageable. +Lifting his disabled leg, he regained control of the machine, +and although wounded in the other leg, he manoeuvred his machine +so skilfully that his observer was able to get several good +bursts into the enemy machines, driving them away. Then, +desperately wounded as he was, Captain West brought the machine +over to his own lines and landed safely. He fainted from loss +of blood and exhaustion, but on regaining consciousness, +insisted on writing his report. Equal to this was the exploit +of Captain Barker, who, in aerial combat, was wounded in the +right and left thigh and had his left arm shattered, +subsequently bringing down an enemy machine in flames, and then +breaking through another hostile formation and reaching the +British lines. + +In recalling such exploits as these, one is tempted on and on, +for it seems that the pilots rivalled each other in their +devotion to duty, this not confined to British aviators, but +common practically to all services. Sufficient instances have +been given to show the nature of the work and the character of +the men who did it. + +The rapid growth of aerial effort rendered it necessary in +January of 1915 to organise the Royal Flying Corps into +separate wings, and in October of the same year it was +constituted in Brigades. In 1916 the Air Board was formed, +mainly with the object of co-ordinating effort and ensuring both +to the R.N.A.S. and to the R.F.C. adequate supplies of material +as far as construction admitted. Under the presidency of Lord +Cowdray, the Air Board brought about certain reforms early in +1917, and in November of that year a separate Air Ministry was +constituted, separating the Air Force from both Navy and Army, +and rendering it an independent force. On April 1st, 1918, the +Royal Air Force came into existence, and unkind critics in the +Royal Flying Corps remarked on the appropriateness of the date. +At the end of the War, the personnel of the Royal Air Force +amounted to 27,906 officers, and 263,842 other ranks. Contrast +of these figures with the number of officers and men who took +the field in 1914 is indicative of the magnitude of British +aerial effort in the War period. + + + +XX. THE WAR PERIOD--II + +There was when War broke out no realisation on the part of the +British Government of the need for encouraging the enterprise of +private builders, who carried out their work entirely at +their-own cost. The importance of a supply of British-built +engines was realised before the War, it is true, and a +competition was held in which a prize of L5,000 was offered for +the best British engine, but this awakening was so late that the +R.F.C. took the field without a single British power plant. +Although Germany woke up equally late to the need for home +produced aeroplane engines, the experience gained in building +engines for dirigibles sufficed for the production of aeroplane +power plants. The Mercedes filled all requirements together +with the Benz and the Maybach. There was a 225 horsepower Benz +which was very popular, as were the 100 horse-power and 170 +horse-power Mercedes, the last mentioned fitted to the Aviatik +biplane of 1917. The Uberursel was a copy of the Gnome and +supplied the need for rotary engines. + +In Great Britain there were a number of aeroplane constructing +firms that had managed to emerge from the lean years 1912-1913 +with sufficient manufacturing plant to give a hand in making up +the leeway of construction when War broke out. Gradually the +motor-car firms came in, turning their body-building departments +to plane and fuselage construction, which enabled them to turn +out the complete planes engined and ready for the field. The +coach-building trade soon joined in and came in handy as +propeller makers; big upholstering and furniture firms and scores +of concerns that had never dreamed of engaging in aeroplane +construction were busy on supplying the R.F.C. By 1915 hundreds +of different firms were building aeroplanes and parts; by 1917 +the number had increased to over 1,000, and a capital of over a +million pounds for a firm that at the outbreak of War had +employed a score or so of hands was by no means uncommon. Women +and girls came into the work, more especially in plane +construction and covering and doping, though they took their +place in the engine shops and proved successful at acetylene +welding and work at the lathes. It was some time before Britain +was able to provide its own magnetos, for this key industry had +been left in the hands of the Germans up to the outbreak of War, +and the 'Bosch' was admittedly supreme--even now it has never +been beaten, and can only be equalled, being as near perfection +as is possible for a magneto. + +One of the great inventions of the War was the synchronisation +of engine-timing and machine gun, which rendered it possible to +fire through the blades of a propeller without damaging them, +though the growing efficiency of the aeroplane as a whole and of +its armament is a thing to marvel at on looking back and +considering what was actually accomplished. As the efficiency +of the aeroplane increased, so anti-aircraft guns and +range-finding were improved. Before the War an aeroplane +travelling at full speed was reckoned perfectly safe at 4,000 +feet, but, by the first month of 1915, the safe height had gone +up to 9,000 feet, 7,000 feet being the limit of rifle and machine +gun bullet trajectory; the heavier guns were not sufficiently +mobile to tackle aircraft. At that time, it was reckoned that +effective aerial photography ceased at 6,000 feet, while +bomb-dropping from 7,000-8,000 feet was reckoned uncertain except +in the case of a very large target. The improvement in +anti-aircraft devices went on, and by May of 1916, an aeroplane +was not safe under 15,000 feet, while anti-aircraft shells had +fuses capable of being set to over 20,000 feet, and bombing from +15,000 and 16,000 feet was common. It was not till later that +Allied pilots demonstrated the safety that lies in flying very +near the ground, this owing to the fact that, when flying swiftly +at a very low altitude, the machine is out of sight almost before +it can be aimed at. + +The Battle of the Somme and the clearing of the air preliminary +to that operation brought the fighting aeroplane pure and simple +with them. Formations of fighting planes preceded reconnaissance +craft in order to clear German machines and observation balloons +out of the sky and to watch and keep down any further enemy +formations that might attempt to interfere with Allied +observation work. The German reply to this consisted in the +formation of the Flying Circus, of which Captain Baron von +Richthofen's was a good example. Each circus consisted of a +large formation of speedy machines, built specially for fighting +and manned by the best of the German pilots. These were sent to +attack at any point along the line where the Allies had got a +decided superiority. + +The trick flying of pre-war days soon became an everyday matter; +Pegoud astonished the aviation world before the War by first +looping the loop, but, before three years of hostilities had +elapsed, looping was part of the training of practically every +pilot, while the spinning nose dive, originally considered fatal, +was mastered, and the tail slide, which consisted of a machine +rising nose upward in the air and falling back on its tail, +became one of the easiest 'stunts' in the pilot's repertoire. +Inherent stability was gradually improved, and, from 1916 onward, +practically every pilot could carry on with his machine-gun or +camera and trust to his machine to fly itself until he was free +to attend to it. There was more than one story of a machine +coming safely to earth and making good landing on its own account +with the pilot dead in his cock-pit. + +Toward the end of the War, the Independent Air Force was formed +as a branch of the R.A.F. with a view to bombing German bases +and devoting its attention exclusively to work behind the enemy +lines. Bombing operations were undertaken by the R.N.A.S. as +early as 1914-1915 against Cuxhaven, Dusseldorf, and +Friedrichshavn, but the supply of material was not sufficient to +render these raids continuous. A separate Brigade, the 8th, was +formed in 1917 to harass the German chemical and iron +industries, the base being in the Nancy area, and this policy +was found so fruitful that the Independent Force was constituted +on the 8th June, 1918. The value of the work accomplished by +this force is demonstrated by the fact that the German High +Command recalled twenty fighting squadrons from the Western +front to counter its activities, and, in addition, took troops +away from the fighting line in large numbers for manning +anti-aircraft batteries and searchlights. The German press of +the last year of the War is eloquent of the damage done in +manufacturing areas by the Independent Force, which, had +hostilities continued a little longer, would have included Berlin +in its activities. + +Formation flying was first developed by the Germans, who made +use of it in the daylight raids against England in 1917. Its +value was very soon realised, and the V formation of wild geese +was adopted, the leader taking the point of the V and his +squadron following on either side at different heights. The air +currents set up by the leading machines were thus avoided by +those in the rear, while each pilot had a good view of the +leader's bombs, and were able to correct their own aim by the +bursts, while the different heights at which they flew rendered +anti-aircraft gun practice less effective. Further, machines +were able to afford mutual protection to each other and any +attacker would be met by machine-gun fire from three or four +machines firing on him from different angles and heights. In +the later formations single-seater fighters flew above the +bombers for the purpose of driving off hostile craft. Formation +flying was not fully developed when the end of the War brought +stagnation in place of the rapid advance in the strategy and +tactics of military air work. + + + +XXI. RECONSTRUCTION + +The end of the War brought a pause in which the multitude of +aircraft constructors found themselves faced with the possible +complete stagnation of the industry, since military activities +no longer demanded their services and the prospects of +commercial flying were virtually nil. That great factor in +commercial success, cost of plant and upkeep, had received no +consideration whatever in the War period, for armies do not +count cost. The types of machines that had evolved from the War +were very fast, very efficient, and very expensive, although the +bombers showed promise of adaptation to commercial needs, and, +so far as other machines were concerned, America had already +proved the possibilities of mail-carrying by maintaining a mail +service even during the War period. + +A civil aviation department of the Air Ministry was formed in +February of 1919 with a Controller General of Civil Aviation +at the head. This was organised into four branches, one dealing +with the survey and preparation of air routes for the British +Empire, one organising meteorological and wireless telegraphy +services, one dealing with the licensing of aerodromes, machines +for passenger or goods carrying and civilian pilots, and one +dealing with publicity and transmission of information +generally. A special Act of Parliament 264 entitled 'The Air +Navigation Acts, 1911-1919,' was passed on February 27th, and +commercial flying was officially permitted from May 1st, 1919. + +Meanwhile the great event of 1919, the crossing of the +Atlantic by air, was gradually ripening to performance. In +addition to the rigid airship, R.34, eight machines entered for +this flight, these being a Short seaplane, Handley-Page, +Martinsyde, Vickers-Vimy, and Sopwith aeroplanes, and three +American flying boats, N.C.1, N.C.3, and N.C.4. The Short +seaplane was the only one of the eight which proposed to make +the journey westward; in flying from England to Ireland, before +starting on the long trip to Newfoundland, it fell into the sea +off the coast of Anglesey, and so far as it was concerned the +attempt was abandoned. + +The first machines to start from the Western end were the three +American seaplanes, which on the morning of May 6th left +Trepassy, Newfoundland, on the 1,380 mile stage to Horta in the +Azores. N.C.1 and N.C.3 gave up the attempt very early, but +N.C.4, piloted by Lieut.-Commander Read, U.S.N., made Horta on +May 17th and made a three days' halt. On the 20th the second +stage of the journey to Ponta Delgada, a further 190 miles, was +completed and a second halt of a week was made. On the 27th, +the machine left for Lisbon, 900 miles distant, and completed +the journey in a day. On the 30th a further stage of 340 miles +took N.C.4 on to Ferrol, and the next day the last stage of 420 +miles to Plymouth was accomplished. + +Meanwhile, H. G. Hawker, pilot of the Sopwith biplane, together +with Commander Mackenzie Grieve, R.N., his navigator, found the +weather sufficiently auspicious to set out at 6.48 p.m. On +Sunday, May 18th, in the hope of completing the trip by the +direct route before N.C.4 could reach Plymouth. They set out +from Mount Pearl aerodrome, St John's, Newfoundland, and vanished +into space, being given up as lost, as Hamel was lost immediately +before the War in attempting to fly the North Sea. There was a +week of dead silence regarding their fate, but on the following +Sunday morning there was world-wide relief at the news that the +plucky attempt had not ended in disaster, but both aviators had +been picked up by the steamer Mary at 9.30 a.m. on the morning of +the 19th, while still about 750 miles short of the conclusion of +their journey. Engine failure brought them down, and they planed +down to the sea close to the Mary to be picked up; as the vessel +was not fitted with wireless, the news of their rescue could not +be communicated until land was reached. An equivalent of half +the L10,000 prize offered by the Daily Mail for the non-stop +flight was presented by the paper in recognition of the very +gallant attempt, and the King conferred the Air Force Cross on +both pilot and navigator. + +Raynham, pilot of the Martinsyde competing machine, had the bad +luck to crash his craft twice in attempting to start before he +got outside the boundary of the aerodrome. The Handley-Page +machine was withdrawn from the competition, and, attempting to +fly to America, was crashed on the way. + +The first non-stop crossing was made on June 14th-15th in 16 +hours 27 minutes, the speed being just over 117 miles per hour. +The machine was a Vickers-Vimy bomber, engined with two +Rolls-Royce Eagle VIII's, piloted by Captain John Alcock, D.S.C., +with Lieut. Arthur Whitten-Brown as navigator. The journey was +reported to be very rough, so much so at times that Captain +Alcock stated that they were flying upside down, and for the +greater part of the time they were out of sight of the sea. Both +pilot and navigator had the honour of knighthood conferred on +them at the conclusion of the journey. + +Meanwhile, commercial flying opened on May 8th (the official +date was May 1st) with a joy-ride service from Hounslow of Avro +training machines. The enterprise caught on remarkably, and the +company extended their activities to coastal resorts for the +holiday season--at Blackpool alone they took up 10,000 +passengers before the service was two months old. Hendon, +beginning passenger flights on the same date, went in for +exhibition and passenger flying, and on June 21st the aerial +Derby was won by Captain Gathergood on an Airco 4R machine with +a Napier 450 horse-power 'Lion' engine; incidentally the speed +of 129.3 miles per hour was officially recognised as constituting +the world's record for speed within a closed circuit. On July +17th a Fiat B.R. biplane with a 700 horse-power engine landed at +Kenley aerodrome after having made a non-stop flight of 1,100 +miles. The maximum speed of this machine was 160 miles per +hour, and it was claimed to be the fastest machine in existence. +On August 25th a daily service between London and Paris was +inaugurated by the Aircraft Manufacturing Company, Limited, who +ran a machine each way each day, starting at 12.30 and due to +arrive at 2.45 p.m. The Handley-Page Company began a similar +service in September of 1919, but ran it on alternate days +with machines capable of accommodating ten passengers. The +single fare in each case was fixed at 15 guineas and the parcel +rate at 7s. 6d. per pound. + +Meanwhile, in Germany, a number of passenger services had been +in operation from the early part of the year; the Berlin-Weimar +service was established on February 5th and Berlin-Hamburg on +March 1st, both for mail and passenger carrying. Berlin-Breslau +was soon added, but the first route opened remained most +popular, 538 flights being made between its opening and the +end of April, while for March and April combined, the +Hamburg-Berlin route recorded only 262 flights. All three +routes were operated by a combine of German aeronautical firms +entitled the Deutsch Luft Rederie. The single fare between +Hamburg and Berlin was 450 marks, between Berlin and Breslau 500 +marks, and between Berlin and Weimar 450 marks. Luggage was +carried free of charge, but varied according to the weight of +the passenger, since the combined weight of both passenger and +luggage was not allowed to exceed a certain limit. + +In America commercial flying had begun in May of 1918 with the +mail service between Washington, Philadelphia, and New York, +which proved that mail carrying is a commercial possibility, and +also demonstrated the remarkable reliability of the modern +aeroplane by making 102 complete flights out of a possible total +of 104 in November, 1918, at a cost of 0.777 of a dollar per +mile. By March of 1919 the cost per mile had gone up to 1.28 +dollars; the first annual report issued at the end of May showed +an efficiency of 95.6 per cent and the original six aeroplanes +and engines with which the service began were still in regular +use. + +In June of 1919 an American commercial firm chartered an +aeroplane for emergency service owing to a New York harbour +strike and found it so useful that they made it a regular +service. The Travellers Company inaugurated a passenger flying +boat service between New York and Atlantic City on July 25th, the +fare, inclusive of 35 lbs. of luggage, being fixed at L25 each +way. + +Five flights on the American continent up to the end of 1919 +are worthy of note. On December 13th, 1918, Lieut. D. Godoy of +the Chilian army left Santiago, Chili, crossed the Andes at a +height of 19,700 feet and landed at Mendoza, the capital of the +wine-growing province of Argentina. On April 19th, 1919, Captain +E. F. White made the first non-stop flight between New York and +Chicago in 6 hours 50 minutes on a D.H.4 machine driven by a +twelve-cylinder Liberty engine. Early in August Major Schroeder, +piloting a French Lepere machine flying at a height of 18,400 +feet, reached a speed of 137 miles per hour with a Liberty motor +fitted with a super-charger. Toward the end of August, Rex +Marshall, on a Thomas-Morse biplane, starting from a height of +17,000 feet, made a glide of 35 miles with his engine cut off, +restarting it when at a height of 600 feet above the ground. +About a month later R. Rohlfe, piloting a Curtiss triplane, broke +the height record by reaching 34,610 feet. + + + +XXII. 1919-20 + +Into the later months of 1919 comes the flight by Captain +Ross-Smith from England to Australia and the attempt to make the +Cape to Cairo voyage by air. The Australian Government had +offered a prize of L10,000 for the first flight from England to +Australia in a British machine, the flight to be accomplished in +720 consecutive hours. Ross-Smith, with his brother, Lieut. +Keith Macpherson Smith, and two mechanics, left Hounslow in a +Vickers-Vimy bomber with Rolls-Royce engine on November 12th and +arrived at Port Darwin, North Australia, on the 10th December, +having completed the flight in 27 days 20 hours 20 minutes, thus +having 51 hours 40 minutes to spare out of the 720 allotted +hours. + +Early in 1920 came a series of attempts at completing the +journey by air between Cairo and the Cape. Out of four +competitors Colonel Van Ryneveld came nearest to making the +journey successfully, leaving England on a standard Vickers-Vimy +bomber with Rolls-Royce engines, identical in design with the +machine used by Captain Ross-Smith on the England to Australia +flight. A second Vickers-Vimy was financed by the Times +newspaper and a third flight was undertaken with a Handley-Page +machine under the auspices of the Daily Telegraph. The Air +Ministry had already prepared the route by means of three survey +parties which cleared the aerodromes and landing grounds, +dividing their journey into stages of 200 miles or less. Not +one of the competitors completed the course, but in both this +and Ross-Smith's flight valuable data was gained in respect of +reliability of machines and engines, together with a mass of +meteorological information. + +The Handley-Page Company announced in the early months of 1920 +that they had perfected a new design of wing which brought about +a twenty to forty per cent improvement in lift rate in the year. +When the nature of the design was made public, it was seen to +consist of a division of the wing into small sections, each with +its separate lift. A few days later, Fokker, the Dutch +inventor, announced the construction of a machine in which all +external bracing wires are obviated, the wings being of a very +deep section and self-supporting. The value of these two +inventions remains to be seen so far as commercial flying is +concerned. + +The value of air work in war, especially so far as the Colonial +campaigns in which British troops are constantly being engaged is +in question, was very thoroughly demonstrated in a report issued +early in 1920 with reference to the successful termination of the +Somaliland campaign through the intervention of the Royal Air +Force, which between January 21st and the 31st practically +destroyed the Dervish force under the Mullah, which had been a +thorn in the side of Britain since 1907. Bombs and machine-guns +did the work, destroying fortifications and bringing about the +surrender of all the Mullah's following, with the exception of +about seventy who made their escape. + +Certain records both in construction and performance had +characterised the post-war years, though as design advances and +comes nearer to perfection, it is obvious that records must get +fewer and farther between. The record aeroplane as regards size +at the time of its construction was the Tarrant triplane, which +made its first--and last--flight on May 28th, 1919. The total +loaded weight was 30 tons, and the machine was fitted with six +400 horse-power engines; almost immediately after the trial +flight began, the machine pitched forward on its nose and was +wrecked, causing fatal injuries to Captains Dunn and Rawlings, +who were aboard the machine. A second accident of similar +character was that which befell the giant seaplane known as the +Felixstowe Fury, in a trial flight. This latter machine was +intended to be flown to Australia, but was crashed over the +water. + +On May 4th, 1920, a British record for flight duration and +useful load was established by a commercial type Handley-Page +biplane, which, carrying a load of 3,690 lbs., rose to a height +of 13,999 feet and remained in the air for 1 hour 20 minutes. +On May 27th the French pilot, Fronval, flying at Villacoublay in +a Morane-Saulnier type of biplane with Le Rhone motor, put up an +extraordinary type of record by looping the loop 962 times in 3 +hours 52 minutes 10 seconds. Another record of the year of +similar nature was that of two French fliers, Boussotrot and +Bernard, who achieved a continuous flight of 24 hours 19 minutes +7 seconds, beating the pre-war record of 21 hours 48 3/4 seconds +set up by the German pilot, Landemann. Both these records are +likely to stand, being in the nature of freaks, which demonstrate +little beyond the reliability of the machine and the capacity for +endurance on the part of its pilots. + +Meanwhile, on February 14th, Lieuts. Masiero and Ferrarin left +Rome on S.V.A. Ansaldo V. machines fitted with 220 horse-power +S.V.A. motors. On May 30th they arrived at Tokio, having flown +by way of Bagdad, Karachi, Canton, Pekin, and Osaka. Several +other competitors started, two of whom were shot down by Arabs in +Mesopotamia. + +Considered in a general way, the first two years after the +termination of the Great European War form a period of transition +in which the commercial type of aeroplane was gradually evolved +from the fighting machine which was perfected in the four +preceding years. There was about this period no sense of +finality, but it was as experimental, in its own way, as were the +years of progressing design which preceded the war period. Such +commercial schemes as were inaugurated call for no more note than +has been given here; they have been experimental, and, with the +possible exception of the United States Government mail service, +have not been planned and executed on a sufficiently large scale +to furnish reliable data on which to forecast the prospects of +commercial aviation. And there is a school rapidly growing up +which asserts that the day of aeroplanes is nearly over. The +construction of the giant airships of to-day and the successful +return flight of R34 across the Atlantic seem to point to the +eventual triumph, in spite of its disadvantages, of the dirigible +airship. + +This is a hard saying for such of the aeroplane industry as +survived the War period and consolidated itself, and it is but +the saying of a section which bases its belief on the fact that, +as was noted in the very early years of the century, the +aeroplane is primarily a war machine. Moreover, the experience +of the War period tended to discredit the dirigible, since, +before the introduction of helium gas, the inflammability of its +buoyant factor placed it at an immense disadvantage beside the +machine dependent on the atmosphere itself for its lift. + +As life runs to-day, it is a long time since Kipling wrote his +story of the airways of a future world and thrust out a prophecy +that the bulk of the world's air traffic would be carried by +gas-bag vessels. If the school which inclines to belief in the +dirigible is right in its belief, as it well may be, then the +foresight was uncannily correct, not only in the matter of the +main assumption, but in the detail with which the writer +embroidered it. + +On the constructional side, the history of the aeroplane is +still so much in the making that any attempt at a critical +history would be unwise, and it is possible only to record fact, +leaving it to the future for judgment to be passed. But, in a +general way, criticism may be advanced with regard to the place +that aeronautics takes in civilisation. In the past hundred +years, the world has made miraculously rapid strides materially, +but moral development has not kept abreast. Conception of the +responsibilities of humanity remains virtually in a position of +a hundred years ago; given a higher conception of life and its +responsibilities, the aeroplane becomes the crowning achievement +of that long series which James Watt inaugurated, the last step +in intercommunication, the chain with which all nations are +bound in a growing prosperity, surely based on moral wellbeing. +Without such conception of the duties as well as the rights of +life, this last achievement of science may yet prove the weapon +that shall end civilisation as men know it to-day, and bring +this ultra-material age to a phase of ruin on which saner people +can build a world more reasonable and less given to groping +after purely material advancement. + + + +PART II + +1903-1920: PROGRESS IN DESIGN +BY LIEUT.-COL. W. LOCKWOOD MARSH + +I. THE BEGINNINGS + +Although the first actual flight of an aeroplane was made by the +Wrights on December 17th 1903, it is necessary, in considering +the progress of design between that period and the present day, +to go back to the earlier days of their experiments with +'gliders,' which show the alterations in design made by them in +their step-bystep progress to a flying machine proper, and give +a clear idea of the stage at which they had arrived in the art +of aeroplane design at the time of their first flights. + +They started by carefully surveying the work of previous +experimenters, such as Lilienthal and Chanute, and from the +lesson of some of the failures of these pioneers evolved certain +new principles which were embodied in their first glider, built +in 1900. In the first place, instead of relying upon the +shifting of the operator's body to obtain balance, which had +proved too slow to be reliable, they fitted in front of the main +supporting surfaces what we now call an 'elevator,' which could +be flexed, to control the longitudinal balance, from where the +operator lay prone upon the main supporting surfaces. The second +main innovation which they incorporated in this first glider, and +the principle of which is still used in every aeroplane in +existence, was the attainment of lateral balance by warping the +extremities of the main planes. The effect of warping or pulling +down the extremity of the wing on one side was to increase its +lift and so cause that side to rise. In the first two gliders +this control was also used for steering to right and left. Both +these methods of control were novel for other than model work, as +previous experimenters, such as Lilienthal and Pilcher, had +relied entirely upon moving the legs or shifting the position of +the body to control the longitudinal and lateral motions of their +gliders. For the main supporting surfaces of the glider the +biplane system of Chanute's gliders was adopted with certain +modifications, while the curve of the wings was founded upon the +calculations of Lilienthal as to wind pressure and consequent +lift of the plane. + +This first glider was tested on the Kill Devil Hill sand-hills +in North Carolina in the summer of 1900 and proved at any +rate the correctness of the principles of the front elevator and +warping wings, though its designers were puzzled by the fact +that the lift was less than they expected; whilst the 'drag'(as +we call it), or resistance, was also considerably lower than +their predictions. The 1901 machine was, in consequence, nearly +doubled in area--the lifting surface being increased from 165 to +308 square feet--the first trial taking place on July 27th, +1901, again at Kill Devil Hill. It immediately appeared that +something was wrong, as the machine dived straight to the +ground, and it was only after the operator's position had been +moved nearly a foot back from what had been calculated as the +correct position that the machine would glide--and even then the +elevator had to be used far more strongly than in the previous +year's glider. After a good deal of thought the apparent +solution of the trouble was finally found. + +This consisted in the fact that with curved surfaces, while at +large angles the centre of pressure moves forward as the angle +decreases, when a certain limit of angle is reached it travels +suddenly backwards and causes the machine to dive. The Wrights +had known of this tendency from Lilienthal's researches, but had +imagined that the phenomenon would disappear if they used a +fairly lightly cambered--or curved--surface with a very abrupt +curve at the front. Having discovered what appeared to be the +cause they surmounted the difficulty by 'trussing down' the +camber of the wings, with the result that they at once got back +to the old conditions of the previous year and could control the +machine readily with small movements of the elevator, even being +able to follow undulations in the ground. They still found, +however, that the lift was not as great as it should have been; +while the drag remained, as in the previous glider, surprisingly +small. This threw doubt on previous figures as to wind +resistance and pressure on curved surfaces; but at the same time +confirmed (and this was a most important result) Lilienthal's +previously questioned theory that at small angles the pressure +on a curved surface instead of being normal, or at right angles +to, the chord is in fact inclined in front of the perpendicular. +The result of this is that the pressure actually tends to draw +the machine forward into the wind--hence the small amount of +drag, which had puzzled Wilbur and Orville Wright. + +Another lesson which was learnt from these first two years of +experiment, was that where, as in a biplane, two surfaces are +superposed one above the other, each of them has somewhat less +lift than it would have if used alone. The experimenters were +also still in doubt as to the efficiency of the warping method +of controlling the lateral balance as it gave rise to certain +phenomena which puzzled them, the machine turning towards the +wing having the greater angle, which seemed also to touch the +ground first, contrary to their expectations. Accordingly, on +returning to Dayton towards the end of 1901, they set +themselves to solve the various problems which had appeared and +started on a lengthy series of experiments to check the previous +figures as to wind resistance and lift of curved surfaces, +besides setting themselves to grapple with the difficulty of +lateral control. They accordingly constructed for themselves at +their home in Dayton a wind tunnel 16 inches square by 6 feet +long in which they measured the lift and 'drag' of more than two +hundred miniature wings. In the course of these tests they for +the first time produced comparative results of the lift of +oblong and square surfaces, with the result that they +re-discovered the importance of 'aspect ratio'--the ratio of +length to breadth of planes. As a result, in the next year's +glider the aspect ration of the wings was increased from the +three to one of the earliest model to about six to one, which is +approximately the same as that used in the machines of to-day. +Further than that, they discussed the question of lateral +stability, and came to the conclusion that the cause of the +trouble was that the effect of warping down one wing was to +increase the resistance of, and consequently slow down, that +wing to such an extent that its lift was reduced sufficiently to +wipe out the anticipated increase in lift resulting from the +warping. From this they deduced that if the speed of the warped +wing could be controlled the advantage of increasing the angle +by warping could be utilised as they originally intended. They +therefore decided to fit a vertical fin at the rear which, if the +machine attempted to turn, would be exposed more and more to the +wind and so stop the turning motion by offering increased +resistance. + +As a result of this laboratory research work the third Wright +glider, which was taken to Kill Devil Hill in September, 1902, +was far more efficient aerodynamically than either of its two +predecessors, and was fitted with a fixed vertical fin at the +rear in addition to the movable elevator in front. According to +Mr Griffith Brewer,[*] this third glider contained 305 square +feet of surface; though there may possibly be a mistake here, as +he states[**] the surface of the previous year's glider to have +been only 290 square feet, whereas Wilbur Wright himself[***] +states it to have been 308 square feet. The matter is not, +perhaps, save historically, of much importance, except that the +gliders are believed to have been progressively larger, and +therefore if we accept Wilbur Wright's own figure of the surface +of the second glider, the third must have had a greater area +than that given by Mr Griffith Brewer. Unfortunately, no +evidence of the Wright Brothers themselves on this point is +available. + +[*] Fourth Wilbur Wright Memorial Lecture, Aeronautical Journal, +Vol. XX, No. 79, page 75. + +[**] Ibid. page 73. + +[***] Ibid. pp. 91 and 102. + +The first glide of the 1902, season was made on September 17th +of that year, and the new machine at once showed itself an +improvement on its predecessors, though subsequent trials showed +that the difficulty of lateral balance had not been entirely +overcome. It was decided, therefore, to turn the vertical fin +at the rear into a rudder by making it movable. At the same +time it was realised that there was a definite relation between +lateral balance and directional control, and the rudder controls +and wing-warping wires were accordingly connected This ended the +pioneer gliding experiments of Wilbur and Orville Wright--though +further glides were made in subsequent years--as the following +year, 1903, saw the first power-driven machine leave the ground. + +To recapitulate--in the course of these original experiments the +Wrights confirmed Lilienthal's theory of the reversal of the +centre of pressure on cambered surfaces at small angles of +incidence: they confirmed the importance of high aspect ratio +in respect to lift: they had evolved new and more accurate +tables of lift and pressure on cambered surfaces: they were the +first to use a movable horizontal elevator for controlling +height: they were the first to adjust the wings to different +angles of incidence to maintain lateral balance: and they were +the first to use the movable rudder and adjustable wings in +combination. + +They now considered that they had gone far enough to justify +them in building a power-driven 'flier,' as they called their +first aeroplane. They could find no suitable engine and so +proceeded to build for themselves an internal combustion engine, +which was designed to give 8 horse-power, but when completed +actually developed about 12-15 horse-power and weighed 240 lbs. +The complete machine weighed about 750 lbs. Further details of +the first Wright aeroplane are difficult to obtain, and even +those here given should be received with some caution. The +first flight was made on December 17th 1903, and lasted 12 +seconds. Others followed immediately, and the fourth lasted 59 +seconds, a distance of 852 feet being covered against a 20-mile +wind. + +The following year they transferred operations to a field +outside Dayton, Ohio (their home), and there they flew a +somewhat larger and heavier machine with which on September 20th +1904, they completed the first circle in the air. In this +machine for the first time the pilot had a seat; all the +previous experiments having been carried out with the operator +lying prone on the lower wing. This was followed next year by +another still larger machine, and on it they carried out many +flights. During the course of these flights they satisfied +themselves as to the cause of a phenomenon which had puzzled +them during the previous year and caused them to fear that they +had not solved the problem of lateral control. They found that +on occasions--always when on a turn--the machine began to slide +down towards the ground and that no amount of warping could stop +it. Finally it was found that if the nose of the machine was +tilted down a recovery could be effected; from which they +concluded that what actually happened was that the machine, +'owing to the increased load caused by centrifugal force,' had +insufficient power to maintain itself in the air and therefore +lost speed until a point was reached at which the controls +became inoperative. In other words, this was the first +experience of 'stalling on a turn,' which is a danger against +which all embryo pilots have to guard in the early stages of +their training. + +The 1905 machine was, like its predecessors, a biplane with a +biplane elevator in front and a double vertical rudder in rear. +The span was 40 feet, the chord of the wings being 6 feet and +the gap between them about the same. The total area was about +600 square feet which supported a total weight of 925 lbs.; +while the motor was 12 to 15 horse-power driving two propellers +on each side behind the main planes through chains and giving +the machine a speed of about 30 m.p.h. one of these chains was +crossed so that the propellers revolved in opposite directions +to avoid the torque which it was feared would be set up if they +both revolved the same way. The machine was not fitted with a +wheeled undercarriage but was carried on two skids, which also +acted as outriggers to carry the elevator. Consequently, a +mechanical method of launching had to be evolved and the machine +received initial velocity from a rail, along which it was drawn +by the impetus provided by the falling of a weight from a wooden +tower or 'pylon.' As a result of this the Wright aeroplane in +its original form had to be taken back to its starting rail +after each flight, and could not restart from the point of +alighting. Perhaps, in comparison with French machines of more +or less contemporary date (evolved on independent lines in +ignorance of the Americans' work), the chief feature of the +Wright biplane of 1905 was that it relied entirely upon the +skill of the operator for its stability; whereas in France some +attempt was being made, although perhaps not very successfully, +to make the machine automatically stable laterally. The +performance of the Wrights in carrying a loading of some 60 lbs. +per horse-power is one which should not be overlooked. The wing +loading was about 1 1/2 lbs. per square foot. + +About the same time that the Wrights were carrying out their +power-driven experiments, a band of pioneers was quite +independently beginning to approach success in France. In +practically every case, however, they started from a somewhat +different standpoint and took as their basic idea the cellular +(or box) kite. This form of kite, consisting of two superposed +surfaces connected at each end by a vertical panel or curtain of +fabric, had proved extremely successful for man-carrying +purposes, and, therefore, it was little wonder that several minds +conceived the idea of attempting to fly by fitting a series of +box-kites with an engine. The first to achieve success was M. +Santos-Dumont, the famous Brazilian pioneer-designer of airships, +who, on November 12th, 1906, made several flights, the last of +which covered a little over 700 feet. Santos-Dumont's machine +consisted essentially of two box-kites, forming the main wings, +one on each side of the body, in which the pilot stood, and at +the front extremity of which was another movable box-kite to act +as elevator and rudder. The curtains at the ends were intended +to give lateral stability, which was further ensured by setting +the wings slightly inclined upwards from the centre, so that when +seen from the front they formed a wide V. This feature is still +to be found in many aeroplanes to-day and has come to be known +as the 'dihedral.' The motor was at first of 24 horse-power, for +which later a 50 horse-power Antoinette engine was substituted; +whilst a three-wheeled undercarriage was provided, so that the +machine could start without external mechanical aid. The +machine was constructed of bamboo and steel, the weight being as +low as 352 lbs. The span was 40 feet, the length being 33 feet, +with a total surface of main planes of 860 square feet. It will +thus be seen--for comparison with the Wright machine--that the +weight per horse-power (with the 50 horse-power engine) was only +7 lbs., while the wing loading was equally low at 1/2 lb. per +square foot. + +The main features of the Santos-Dumont machine were the box-kite +form of construction, with a dihedral angle on the main planes, +and the forward elevator which could be moved in any direction +and therefore acted in the same way as the rudder at the rear of +the Wright biplane. It had a single propeller revolving in the +centre behind the wings and was fitted with an undercarriage +incorporated in the machine. + +The other chief French experimenters at this period were the +Voisin Freres, whose first two machines--identical in +form--were sold to Delagrange and H. Farman, which has sometimes +caused confusion, the two purchasers being credited with the +design they bought. The Voisins, like the Wrights, based their +designs largely on the experimental work of Lilienthal, Langley, +Chanute, and others, though they also carried out tests on the +lifting properties of aerofoils in a wind tunnel of their own. +Their first machines, like those of Santos-Dumont, showed the +effects of experimenting with box-kites, some of which they had +built for M. Ernest Archdeacon in 1904. In their case the +machine, which was again a biplane, had, like both the others +previously mentioned, an elevator in front--though in this case +of monoplane form--and, as in the Wright, a rudder was fitted in +rear of the main planes. The Voisins, however, fitted a fixed +biplane horizontal 'tail'--in an effort to obtain a measure of +automatic longitudinal stability--between the two surfaces of +which the single rudder worked. For lateral stability they +depended entirely on end curtains between the upper and lower +surfaces of both the main planes and biplane tail surfaces. +They, like Santos-Dumont, fitted a wheeled undercarriage, so +that the machine was self-contained. The Voisin machine, then, +was intended to be automatically stable in both senses; whereas +the Wrights deliberately produced a machine which was entirely +dependent upon the pilot's skill for its stability. The +dimensions of the Voisin may be given for comparative purposes, +and were as follows: Span 33 feet with a chord (width from back +to front) of main planes of 6 1/2 feet, giving a total area of +430 square feet. The 50 horse-power Antoinette engine, which was +enclosed in the body (or 'nacelle ') in the front of which the +pilot sat, drove a propeller behind, revolving between the +outriggers carrying the tail. The total weight, including Farman +as pilot, is given as 1,540 lbs., so that the machine was much +heavier than either of the others; the weight per horse-power +being midway between the Santos-Dumont and the Wright at 31 lbs. +per square foot, while the wing loading was considerably greater +than either at 3 1/2 lbs. per square foot. The Voisin machine +was +experimented with by Farman and Delagrange from about June 1907 +onwards, and was in the subsequent years developed by Farman; and +right up to the commencement of the War upheld the principles of +the box-kite method of construction for training purposes. The +chief modification of the original design was the addition of +flaps (or ailerons) at the rear extremities of the main planes to +give lateral control, in a manner analogous to the wing-warping +method invented by the Wrights, as a result of which the end +curtains between the planes were abolished. An additional +elevator was fitted at the rear of the fixed biplane tail, which +eventually led to the discarding of the front elevator +altogether. During the same period the Wright machine came into +line with the others by the fitting of a wheeled undercarriage +integral with the machine. A fixed horizontal tail was also +added to the rear rudder, to which a movable elevator was later +attached; and, finally, the front elevator was done away with. +It will thus be seen that having started from the very different +standpoints of automatic stability and complete control by the +pilot, the Voisin (as developed in the Farman) and Wright +machines, through gradual evolution finally resulted in +aeroplanes of similar characteristics embodying a modicum of +both features. + +Before proceeding to the next stage of progress mention should +be made of the experimental work of Captain Ferber in France. +This officer carried out a large number of experiments with +gliders contemporarily with the Wrights, adopting--like +them--the Chanute biplane principle. He adopted the front +elevator from the Wrights, but immediately went a step farther +by also fitting a fixed tail in rear, which did not become a +feature of the Wright machine until some seven or eight years +later. He built and appeared to have flown a machine fitted +with a motor in 1905, and was commissioned to go to America by +the French War Office on a secret mission to the Wrights. +Unfortunately, no complete account of his experiments appears to +exist, though it can be said that his work was at least as +important as that of any of the other pioneers mentioned. + + + +II. MULTIPLICITY OF IDEAS + +In a review of progress such as this, it is obviously +impossible, when a certain stage of development has been +reached, owing to the very multiplicity of experimenters, to +continue dealing in anything approaching detail with all the +different types of machines; and it is proposed, therefore, from +this point to deal only with tendencies, and to mention +individuals merely as examples of a class of thought rather than +as personalities, as it is often difficult fairly to allocate +the responsibility for any particular innovation. + +During 1907 and 1908 a new type of machine, in the monoplane, +began to appear from the workshops of Louis Bleriot, Robert +Esnault-Pelterie, and others, which was destined to give rise to +long and bitter controversies on the relative advantages of the +two types, into which it is not proposed to enter here; though +the rumblings of the conflict are still to be heard by +discerning ears. Bleriot's early monoplanes had certain new +features, such as the location of the pilot, and in some cases +the engine, below the wing; but in general his monoplanes, +particularly the famous No. XI on which the first Channel +crossing was made on July 25th, 1909, embodied the main +principles of the Wright and Voisin types, except that the +propeller was in front of instead of behind the supporting +surfaces, and was, therefore, what is called a 'tractor' in +place of the then more conventional 'pusher.' Bleriot aimed at +lateral balance by having the tip of each wing pivoted, though he +soon fell into line with the Wrights and adopted the warping +system. The main features of the design of Esnault-Pelterie's +monoplane was the inverted dihedral (or kathedral as this was +called in Mr S. F. Cody's British Army Biplane of 1907) on the +wings, whereby the tips were considerably lower than the roots at +the body. This was designed to give automatic lateral stability, +but, here again, conventional practice was soon adopted and the +R.E.P. monoplanes, which became well-known in this country +through their adoption in the early days by Messrs Vickers, were +of the ordinary monoplane design, consisting of a tractor +propeller with wire-stayed wings, the pilot being in an enclosed +fuselage containing the engine in front and carrying at its rear +extremity fixed horizontal and vertical surfaces combined with +movable elevators and rudder. Constructionally, the R.E.P. +monoplane was of extreme interest as the body was constructed of +steel. The Antoinette monoplane, so ably flown by Latham, was +another very famous machine of the 1909-1910 period, though its +performance were frequently marred by engine failure; which was +indeed the bugbear of all these early experimenters, and it is +difficult to say, after this lapse of time, how far in many cases +the failures which occurred, both in performances and even in the +actual ability to rise from the ground, were due to defects in +design or merely faults in the primitive engines available. The +Antoinette aroused admiration chiefly through its graceful, +birdlike lines, which have probably never been equalled; but its +chief interest for our present purpose lies in the novel method +of wing-staying which was employed. Contemporary monoplanes +practically all had their wings stayed by wires to a post in the +centre above the fuselage, and, usually, to the undercarriage +below. In the Antoinette, however, a king post was introduced +half-way along the wing, from which wires were carried to the +ends of the wings and the body. This was intended to give +increased strength and permitted of a greater wing-spread and +consequently improved aspect ratio. The same system of +construction was adopted in the British Martinsyde monoplanes of +two or three years later. + +This period also saw the production of the first triplane, which +was built by A. V. Roe in England and was fitted with a J.A.P. +engine of only 9 horse-power--an amazing performance which +remains to this day unequalled. Mr Roe's triplane was chiefly +interesting otherwise for the method of maintaining longitudinal +control, which was achieved by pivoting the whole of the three +main planes so that their angle of incidence could be altered. +This was the direct converse of the universal practice of +elevating by means of a subsidiary surface either in front or +rear of the main planes. + +Recollection of the various flying meetings and exhibitions +which one attended during the years from 1909 to 1911, or even +1912 are chiefly notable for the fact that the first thought on +seeing any new type of machine was not as to what its +'performance'--in speed, lift, or what not--would be; but +speculation as to whether it would leave the ground at all when +eventually tried. This is perhaps the best indication of the +outstanding characteristic of that interim period between the +time of the first actual flights and the later period, +commencing about 1912, when ideas had become settled and it +was at last becoming possible to forecast on the drawing-board +the performance of the completed machine in the air. Without +going into details, for which there is no space here, it is +difficult to convey the correct impression of the chaotic state +which existed as to even the elementary principles of aeroplane +design. All the exhibitions contained large numbers--one had +almost written a majority--of machines which embodied the most +unusual features and which never could, and in practice never +did, leave the ground. At the same time, there were few who +were sufficiently hardy to say certainly that this or that +innovation was wrong; and consequently dozens of inventors in +every country were conducting isolated experiments on both good +and bad lines. All kinds of devices, mechanical and otherwise, +were claimed as the solution of the problem of stability, and +there was even controversy as to whether any measure of +stability was not undesirable; one school maintaining that the +only safety lay in the pilot having the sole say in the attitude +of the machine at any given moment, and fearing danger from the +machine having any mind of its own, so to speak. There was, as +in most controversies, some right on both sides, and when we +come to consider the more settled period from 1912 to the +outbreak of the War in 1914 we shall find how a compromise was +gradually effected. + +At the same time, however, though it was at the time difficult +to pick out, there was very real progress being made, and, +though a number of 'freak' machines fell out by the wayside, the +pioneer designers of those days learnt by a process of trial and +error the right principles to follow and gradually succeeded in +getting their ideas crystallised. + +In connection with stability mention must be made of a machine +which was evolved in the utmost secrecy by Mr J. W. Dunne in a +remote part of Scotland under subsidy from the War office. This +type, which was constructed in both monoplane and biplane form, +showed that it was in fact possible in 1910 and 1911 to design an +aeroplane which could definitely be left to fly itself in the +air. One of the Dunne machines was, for example flown from +Farnborough to Salisbury Plain without any control other than the +rudder being touched; and on another occasion it flew a complete +circle with all controls locked automatically assuming the +correct bank for the radius of turn. The peculiar form of wing +used, the camber of which varied from the root to the tip, gave +rise however, to a certain loss in efficiency, and there was also +a difficulty in the pilot assuming adequate control when desired. +Other machines designed to be stable--such as the German Etrich +and the British Weiss gliders and Handley-Page monoplanes--were +based on the analogy of a wing attached to a certain seed found +in Nature (the 'Zanonia' leaf), on the righting effect of +back-sloped wings combined with upturned (or 'negative') tips. +Generally speaking, however, the machines of the 1909-1912 period +relied for what automatic stability they had on the principle of +the dihedral angle, or flat V, both longitudinally and laterally. +Longitudinally this was obtained by setting the tail at a +slightly smaller angle than the main planes. + +The question of reducing the resistance by adopting 'stream-line' +forms, along which the air could flow uninterruptedly without the +formation of eddies, was not at first properly realised, though +credit should be given to Edouard Nieuport, who in 1909 produced +a monoplane with a very large body which almost completely +enclosed the pilot and made the machine very fast, for those +days, with low horse-power. On one of these machines C. T. +Weyman won the Gordon-Bennett Cup for America in 1911 and +another put up a fine performance in the same race with only a 30 +horse-power engine. The subject, was however, early taken up by +the British Advisory Committee for Aeronautics, which was +established by the Government in 1909, and designers began to +realise the importance of streamline struts and fuselages towards +the end of this transition period. These efforts were at first +not always successful and showed at times a lack of understanding +of the problems involved, but there was a very marked improvement +during the year 1912. At the Paris Aero Salon held early in that +year there was a notable variety of ideas on the subject; whereas +by the time of the one held in October designs had considerably +settled down, more than one exhibitor showing what were called +'monocoque' fuselages completely circular in shape and having +very low resistance, while the same show saw the introduction of +rotating cowls over the propeller bosses, or 'spinners,' as they +came to be called during the War. A particularly fine example of +stream-lining was to be found in the Deperdussin monoplane on +which Vedrines won back the Gordon-Bennett Aviation Cup from +America at a speed of 105.5 m.p.h.--a considerable improvement on +the 78 m.p.h. of the preceding year, which was by no means +accounted for by the mere increase in engine power from 100 +horse-power to 140 horse-power. This machine was the first in +which the refinement of 'stream-lining' the pilot's head, which +became a feature of subsequent racing machines, was introduced. +This consisted of a circular padded excresence above the cockpit +immediately behind the pilot's head, which gradually tapered off +into the top surface of the fuselage. The object was to give the +air an uninterrupted flow instead of allowing it to be broken up +into eddies behind the head of the pilot, and it also provided a +support against the enormous wind-pressure encountered. This +true stream-line form of fuselage owed its introduction to the +Paulhan-Tatin 'Torpille' monoplane of the Paris Salon of early +1917. Altogether the end of the year 1912 began to see the +disappearance of 'freak' machines with all sorts of original +ideas for the increase of stability and performance. Designs had +by then gradually become to a considerable extent standardised, +and it had become unusual to find a machine built which would +fail to fly. The Gnome engine held the field owing to its +advantages, as the first of the rotary type, in lightness and +ease of fitting into the nose of a fuselage. The majority of +machines were tractors (propeller in front) although a +preference, which died down subsequently, was still shown for the +monoplane over the biplane. This year also saw a great increase +in the number of seaplanes, although the 'flying boat' type had +only appeared at intervals and the vast majority were of the +ordinary aeroplane type fitted with floats in place of the land +undercarriage; which type was at that time commonly called +'hydro-aeroplane.' The usual horse power was 50--that of the +smallest Gnome engine--although engines of 100 to 140 horse-power +were also fitted occasionally. The average weight per +horse-power varied from 18 to 25 lbs., while the wing-loading was +usually in the neighbourhood of 5 to 6 lbs. per square foot. The +average speed ranged from 65-75 miles per hour. + + + +III. PROGRESS ON STANDARDISED LINES + +In the last section an attempt has been made to show how, during +what was from the design standpoint perhaps the most critical +period, order gradually became evident out of chaos, +ill-considered ideas dropped out through failure to make good, +and, though there was still plenty of room for improvement in +details, the bulk of the aeroplanes showed a general similarity +in form and conception. There was still a great deal to be +learnt in finding the best form of wing section, and performances +were still low; but it had become definitely possible to say that +flying had emerged from the chrysalis stage and had become a +science. The period which now began was one of scientific +development and improvement--in performance, manoeuvrability, +and general airworthiness and stability. + +The British Military Aeroplane Competition held in the summer of +1912 had done much to show the requirements in design by giving +possibly the first opportunity for a definite comparison of the +performance of different machines as measured by impartial +observers on standard lines--albeit the methods of measuring were +crude. These showed that a high speed--for those days--of 75 +miles an hour or so was attended by disadvantages in the form of +an equally fast low speed, of 50 miles per hour or more, and +generally may be said to have given designers an idea what to aim +for and in what direction improvements were required. In fact, +the most noticeable point perhaps of the machines of this time +was the marked manner in which a machine that was good in one +respect would be found to be wanting in others. It had not yet +been possible to combine several desirable attributes in one +machine. The nearest approach to this was perhaps to be found +in the much discussed Government B.E.2 machine, which was +produced from the Royal Aircraft Factory at Farnborough, in the +summer of 1912. Though considerably criticized from many points +of view it was perhaps the nearest approach to a machine of +all-round efficiency that had up to that date appeared. The +climbing rate, which subsequently proved so important for +military purposes, was still low, seldom, if ever, exceeding 400 +feet per minute; while gliding angles (ratio of descent to +forward travel over the ground with engine stopped) little +exceeded 1 in 8. + +The year 1912 and 1913 saw the subsequently all-conquering +tractor biplane begin to come into its own. This type, which +probably originated in England, and at any rate attained to its +greatest excellence prior to the War from the drawing offices of +the Avro Bristol and Sopwith firms, dealt a blow at the monoplane +from which the latter never recovered. + +The two-seater tractor biplane produced by Sopwith and piloted +by H. G. Hawker, showed that it was possible to produce a +biplane with at least equal speed to the best monoplanes, whilst +having the advantage of greater strength and lower landing +speeds. The Sopwith machine had a top speed of over 80 miles an +hour while landing as slowly as little more than 30 miles an +hour; and also proved that it was possible to carry 3 passengers +with fuel for 4 hours' flight with a motive power of only 80 +horse-power. This increase in efficiency was due to careful +attention to detail in every part, improved wing sections, clean +fuselage-lines, and simplified undercarriages. At the same +time, in the early part of 1913 a tendency manifested itself +towards the four-wheeled undercarriage, a pair of smaller wheels +being added in front of the main wheels to prevent overturning +while running on the ground; and several designs of +oleo-pneumatic and steel-spring undercarriages were produced in +place of the rubber shock-absorber type which had up till then +been almost universal. + +These two statements as to undercarriage designs may appear to +be contradictory, but in reality they do not conflict as they +both showed a greater attention to the importance of good +springing, combined with a desire to avoid complication and a +mass of struts and wires which increased head resistance. + +The Olympia Aero Show of March, 1913, also produced a machine +which, although the type was not destined to prove the best for +the purpose for which it was designed, was of interest as being +the first to be designed specially for war purposes. This was +the Vickers 'Gun-bus,' a 'pusher' machine, with the propeller +revolving behind the main planes between the outriggers carrying +the tail, with a seat right in front for a gunner who was +provided with a machine gun on a swivelling mount which had a +free field of fire in every direction forward. The device which +proved the death-blow for this type of aircraft during the war +will be dealt with in the appropriate place later, but the +machine should not go unrecorded. + +As a result of a number of accidents to monoplanes the +Government appointed a Committee at the end of 1912 to inquire +into the causes of these. The report which was presented in +March, 1913, exonerated the monoplane by coming to the +conclusion that the accidents were not caused by conditions +peculiar to monoplanes, but pointed out certain desiderata in +aeroplane design generally which are worth recording. They +recommended that the wings of aeroplanes should be so internally +braced as to have sufficient strength in themselves not to +collapse if the external bracing wires should give way. The +practice, more common in monoplanes than biplanes, of carrying +important bracing wires from the wings to the undercarriage was +condemned owing to the liability of damage from frequent +landings. They also pointed out the desirability of duplicating +all main wires and their attachments, and of using stranded +cable for control wires. Owing to the suspicion that one +accident at least had been caused through the tearing of the +fabric away from the wing, it was recommended that fabric should +be more securely fastened to the ribs of the wings, and that +devices for preventing the spreading of tears should be +considered. In the last connection it is interesting to note +that the French Deperdussin firm produced a fabric wing-covering +with extra strong threads run at right-angles through the fabric +at intervals in order to limit the tearing to a defined area. + +In spite, however, of the whitewashing of the monoplane by the +Government Committee just mentioned, considerable stir was +occasioned later in the year by the decision of the War office +not to order any more monoplanes; and from this time forward +until the War period the British Army was provided exclusively +with biplanes. Even prior to this the popularity of the +monoplane had begun to wane. At the Olympia Aero Show in March, +1913, biplanes for the first time outnumbered the +'single-deckers'(as the Germans call monoplanes); which had the +effect of reducing the wing-loading. In the case of the +biplanes exhibited this averaged about 4 1/2 lbs. per square +foot, while in the case of the monoplanes in the same exhibition +the lowest was 5 1/2 lbs., and the highest over 8 1/2 lbs. per +square foot of area. It may here be mentioned that it was not +until the War period that the importance of loading per +horse-power was recognised as the true criterion of aeroplane +efficiency, far greater interest being displayed in the amount +of weight borne per unit area of wing. + +An idea of the state of development arrived at about this time +may be gained from the fact that the Commandant of the Military +Wing of the Royal Flying Corps in a lecture before the Royal +Aeronautical Society read in February, 1913, asked for +single-seater scout aeroplanes with a speed of 90 miles an hour +and a landing speed of 45 miles an hour--a performance which +even two years later would have been considered modest in the +extreme. It serves to show that, although higher performances +were put up by individual machines on occasion, the general +development had not yet reached the stage when such performances +could be obtained in machines suitable for military purposes. +So far as seaplanes were concerned, up to the beginning of 1913 +little attempt had been made to study the novel problems +involved, and the bulk of the machines at the Monaco Meeting in +April, 1913, for instance, consisted of land machines fitted with +floats, in many cases of a most primitive nature, without other +alterations. Most of those which succeeded in leaving the water +did so through sheer pull of engine power; while practically all +were incapable of getting off except in a fair sea, which enabled +the pilot to jump the machine into the air across the trough +between two waves. Stability problems had not yet been +considered, and in only one or two cases was fin area added at +the rear high up, to counterbalance the effect of the floats low +down in front. Both twin and single-float machines were used, +while the flying boat was only just beginning to come into being +from the workshops of Sopwith in Great Britain, Borel-Denhaut in +France, and Curtiss in America. In view of the approaching +importance of amphibious seaplanes, mention should be made of the +flying boat (or 'bat boat' as it was called, following Rudyard +Kipling) which was built by Sopwith in 1913 with a wheeled +landing-carriage which could be wound up above the bottom surface +of the boat so as to be out of the way when alighting on water. + +During 1913 the (at one time almost universal) practice +originated by the Wright Brothers, of warping the wings for +lateral stability, began to die out and the bulk of aeroplanes +began to be fitted with flaps (or 'ailerons') instead. This +was a distinct change for the better, as continually warping the +wings by bending down the extremities of the rear spars was +bound in time to produce 'fatigue' in that member and lead to +breakage; and the practice became completely obsolete during the +next two or three years. + +The Gordon-Bennett race of September, 1913, was again won by +a Deperdussin machine, somewhat similar to that of the previous +year, but with exceedingly small wings, only 107 square feet in +area. The shape of these wings was instructive as showing how +what, from the general utility point of view, may be +disadvantageous can, for a special purpose, be turned to +account. With a span of 21 feet, the chord was 5 feet, giving +the inefficient 'aspect ratio' of slightly over 4 to 1 only. +The object of this was to reduce the lift, and therefore the +resistance, to as low a point as possible. The total weight was +1,500 lbs., giving a wing-loading of 14 lbs. per square foot--a +hitherto undreamt-of figure. The result was that the machine +took an enormously long run before starting; and after touching +the ground on landing ran for nearly a mile before stopping; but +she beat all records by attaining a speed of 126 miles per +hour. Where this performance is mainly interesting is in +contrast to the machines of 1920, which with an even higher +speed capacity would yet be able to land at not more than 40 or +50 miles per hour, and would be thoroughly efficient flying +machines. + +The Rheims Aviation Meeting, at which the Gordon-Bennett race +was flown, also saw the first appearance of the Morane 'Parasol' +monoplane. The Morane monoplane had been for some time an +interesting machine as being the only type which had no fixed +surface in rear to give automatic stability, the movable +elevator being balanced through being hinged about one-third of +the way back from the front edge. This made the machine +difficult to fly except in the hands of experts, but it was very +quick and handy on the controls and therefore useful for racing +purposes. In the 'Parasol' the modification was introduced of +raising the wing above the body, the pilot looking out beneath +it, in order to give as good a view as possible. + +Before passing to the year 1914 mention should be made of the +feat performed by Nesteroff, a Russian, and Pegoud, a French +pilot, who were the first to demonstrate the possibilities of +flying upside-down and looping the loop. Though perhaps not +coming strictly within the purview of a chapter on design +(though certain alterations were made to the top wing-bracing of +the machine for this purpose) this performance was of extreme +importance to the development of aviation by showing the +possibility of recovering, given reasonable height, from any +position in the air; which led designers to consider the extra +stresses to which an aeroplane might be subjected and to take +steps to provide for them by increasing strength where +necessary. + +When the year 1914 opened a speed of 126 miles per hour had been +attained and a height of 19,600 feet had been reached. The +Sopwith and Avro (the forerunner of the famous training machine +of the War period) were probably the two leading tractor +biplanes of the world, both two-seaters with a speed variation +from 40 miles per hour up to some 90 miles per hour with 80 +horse-power engines. The French were still pinning their faith +mainly to monoplanes, while the Germans were beginning to come +into prominence with both monoplanes and biplanes of the 'Taube' +type. These had wings swept backward and also upturned at the +wing-tips which, though it gave a certain measure of automatic +stability, rendered the machine somewhat clumsy in the air, and +their performances were not on the whole as high as those of +either France or Great Britain. + +Early in 1914 it became known that the experimental work of +Edward Busk--who was so lamentably killed during an experimental +flight later in the year--following upon the researches of +Bairstow and others had resulted in the production at the Royal +Aircraft Factory at Farnborough of a truly automatically stable +aeroplane. This was the 'R.E.' (Reconnaissance Experimental), a +development of the B.E. which has already been referred to. The +remarkable feature of this design was that there was no +particular device to which one could point out as the cause of +the stability. The stable result was attained simply by detailed +design of each part of the aeroplane, with due regard to its +relation to, and effect on, other parts in the air. Weights and +areas were so nicely arranged that under practically any +conditions the machine tended to right itself. It did not, +therefore, claim to be a machine which it was impossible to +upset, but one which if left to itself would tend to right itself +from whatever direction a gust might come. When the principles +were extended to the 'B.E. 2c' type (largely used at the outbreak +of the War) the latter machine, if the engine were switched of f +at a height of not less than 1,000 feet above the ground, would +after a few moments assume its correct gliding angle and glide +down to the ground. + +The Paris Aero Salon of December, 1913, had been remarkable +chiefly for the large number of machines of which the chassis and +bodywork had been constructed of steel-tubing; for the excess of +monoplanes over biplanes; and (in the latter) predominance of +'pusher' machines (with propeller in rear of the main planes) +compared with the growing British preference for 'tractors' (with +air screw in front). Incidentally, the Maurice Farman, the last +relic of the old type box-kite with elevator in front appeared +shorn of this prefix, and became known as the 'short-horn' in +contradistinction to its front-elevatored predecessor which, +owing to its general reliability and easy flying capabilities, +had long been affectionately called the 'mechanical cow.' The +1913 Salon also saw some lingering attempts at attaining +automatic stability by pendulum and other freak devices. + +Apart from the appearance of 'R.E.1,' perhaps the most notable +development towards the end of 1913 was the appearance of the +Sopwith 'Tabloid 'tractor biplane. This single-seater machine, +evolved from the two-seater previously referred to, fitted with a +Gnome engine of 80 horse-power, had the, for those days, +remarkable speed of 92 miles an hour; while a still more +notable feature was that it could remain in level flight at not +more than 37 miles per hour. This machine is of particular +importance because it was the prototype and forerunner of the +successive designs of single-seater scout fighting machines +which were used so extensively from 1914 to 1918. It was also +probably the first machine to be capable of reaching a height of +1,000 feet within one minute. It was closely followed by the +'Bristol Bullet,' which was exhibited at the Olympia Aero Show +of March, 1914. This last pre-war show was mainly remarkable +for the good workmanship displayed--rather than for any distinct +advance in design. In fact, there was a notable diversity in +the types displayed, but in detailed design considerable +improvements were to be seen, such as the general adoption of +stranded steel cable in place of piano wire for the mail bracing + + + +IV. THE WAR PERIOD + +Up to this point an attempt has been made to give some idea of +the progress that was made during the eleven years that had +elapsed since the days of the Wrights' first flights. Much +advance had been made and aeroplanes had settled down, +superficially at any rate, into more or less standardised forms +in three main types--tractor monoplanes, tractor biplanes, and +pusher biplanes. Through the application of the results of +experiments with models in wind tunnels to full-scale machines, +considerable improvements had been made in the design of wing +sections, which had greatly increased the efficiency of +aeroplanes by raising the amount of 'lift' obtained from the +wing compared with the 'drag' (or resistance to forward motion) +which the same wing would cause. In the same way the shape of +bodies, interplane struts, etc., had been improved to be of +better stream-line shape, for the further reduction of +resistance; while the problems of stability were beginning to be +tolerably well understood. Records (for what they are worth) +stood at 21,000 feet as far as height was concerned, 126 miles +per hour for speed, and 24 hours duration. That there was +considerable room for development is, however, evidenced by a +statement made by the late B. C. Hucks (the famous pilot) in +the course of an address delivered before the Royal Aeronautical +Society in July, 1914. 'I consider,' he said, 'that the present +day standard of flying is due far more to the improvement in +piloting than to the improvement in machines.... I consider +those (early 1914) machines are only slight improvements on the +machines of three years ago, and yet they are put through +evolutions which, at that time, were not even dreamed of. I can +take a good example of the way improvement in piloting has +outdistanced improvement in machines--in the case of myself, my +'looping' Bleriot. Most of you know that there is very little +difference between that machine and the 50 horse-power Bleriot +of three years ago.' This statement was, of course, to some +extent an exaggeration and was by no means agreed with by +designers, but there was at the same time a germ of truth in it. +There is at any rate little doubt that the theory and practice +of aeroplane design made far greater strides towards becoming an +exact science during the four years of War than it had done +during the six or seven years preceding it. + +It is impossible in the space at disposal to treat of this +development even with the meagre amount of detail that has been +possible while covering the 'settling down' period from 1911 to +1914, and it is proposed, therefore, to indicate the improvements +by sketching briefly the more noticeable difference in various +respects between the average machine of 1914 and a similar +machine of 1918. + +In the first place, it was soon found that it was possible to +obtain greater efficiency and, in particular, higher speeds, +from tractor machines than from pusher machines with the air +screw behind the main planes. This was for a variety of reasons +connected with the efficiency of propellers and the possibility +of reducing resistance to a greater extent in tractor machines +by using a 'stream-line' fuselage (or body) to connect the main +planes with the tail. Full advantage of this could not be +taken, however, owing to the difficulty of fixing a machine-gun +in a forward direction owing to the presence of the propeller. +This was finally overcome by an ingenious device (known as an +'Interrupter gear') which allowed the gun to fire only when +none of the propeller blades was passing in front of the muzzle. +The monoplane gradually fell into desuetude, mainly owing to the +difficulty of making that type adequately strong without it +becoming prohibitively heavy, and also because of its high +landing speed and general lack of manoeuvrability. The triplane +was also little used except in one or two instances, and, +practically speaking, every machine was of the biplane tractor +type. + +A careful consideration of the salient features leading to +maximum efficiency in aeroplanes--particularly in regard to +speed and climb, which were the two most important military +requirements--showed that a vital feature was the reduction in +the amount of weight lifted per horse-power employed; which in +1914 averaged from 20 to 25 lbs. This was effected both by +gradual increase in the power and size of the engines used and +by great improvement in their detailed design (by increasing +compression ratio and saving weight whenever possible); with the +result that the motive power of single-seater aeroplanes rose +from 80 and 100 horse-power in 1914 to an average of 200 to 300 +horse-power, while the actual weight of the engine fell from 3 +1/2-4 lbs. per horse-power to an average of 2 1/2 lbs. per +horse-power. This meant that while a pre-war engine of 100 +horse-power would weigh some 400 lbs., the 1918 engine developing +three times the power would have less than double the weight. +The result of this improvement was that a scout aeroplane at the +time of the Armistice would have 1 horse-power for every 8 lbs. +of weight lifted, compared with the 20 or 25 lbs. of its 1914 +predecessors. This produced a considerable increase in the rate +of climb, a good postwar machine being able to reach 10,000 feet +in about 5 minutes and 20,000 feet in under half an hour. The +loading per square foot was also considerably increased; this +being rendered possible both by improvement in the design of wing +sections and by more scientific construction giving increased +strength. It will be remembered that in the machine of the very +early period each square foot of surface had only to lift a +weight of some 1 1/2 to 2 lbs., which by 1914 had been increased +to about 4 lbs. By 1918 aeroplanes habitually had a loading of 8 +lbs. or more per square foot of area; which resulted in great +increase in speed. Although a speed of 126 miles per hour had +been attained by a specially designed racing machine over a short +distance in 1914, the average at that period little exceeded, if +at all, 100 miles per hour; whereas in 1918 speeds of 130 miles +per hour had become a commonplace, and shortly afterwards a speed +of over 166 miles an hour was achieved. + +In another direction, also, that of size, great developments +were made. Before the War a few machines fitted with more than +one engine had been built (the first being a triple +Gnome-engined biplane built by Messrs Short Bros. at Eastchurch +in 1913), but none of large size had been successfully produced, +the total weight probably in no case exceeding about 2 tons. In +1916, however, the twin engine Handley-Page biplane was +produced, to be followed by others both in this country and +abroad, which represented a very great increase in size and, +consequently, load-carrying capacity. By the end of the War +period several types were in existence weighing a total of 10 +tons when fully loaded, of which some 4 tons or more represented +'useful load' available for crew, fuel, and bombs or passengers. +This was attained through very careful attention to detailed +design, which showed that the material could be employed more +efficiently as size increased, and was also due to the fact that +a large machine was not liable to be put through the same +evolutions as a small machine, and therefore could safely be +built with a lower factor of safety. Owing to the fact that a +wing section which is adopted for carrying heavy loads usually +has also a somewhat low lift to drag ratio, and is not therefore +productive of high speed, these machines are not as fast as +light scouts; but, nevertheless, they proved themselves capable +of achieving speeds of 100 miles an hour or more in some cases; +which was faster than the average small machine of 1914. + +In one respect the development during the War may perhaps have +proved to be somewhat disappointing, as it might have been +expected that great improvements would be effected in metal +construction, leading almost to the abolition of wooden +structures. Although, however, a good deal of experimental work +was done which resulted in overcoming at any rate the worst of +the difficulties, metal-built machines were little used (except +to a certain extent in Germany) chiefly on account of the need +for rapid production and the danger of delay resulting from +switching over from known and tried methods to experimental +types of construction. The Germans constructed some large +machines, such as the giant Siemens-Schukhert machine, entirely +of metal except for the wing covering, while the Fokker and +Junker firms about the time of the Armistice in 1918 both +produced monoplanes with very deep all-metal wings (including +the covering) which were entirely unstayed externally, depending +for their strength on internal bracing. In Great Britain cable +bracing gave place to a great extent to 'stream-line wires,' +which are steel rods rolled to a more or less oval section, +while tie-rods were also extensively used for the internal +bracing of the wings. Great developments in the economical use +of material were also made in the direction of using built-up +main spars for the wings and interplane struts; spars composed +of a series of layers (or 'laminations') of different pieces of +wood also being used. + +Apart from the metallic construction of aeroplanes an enormous +amount of work was done in the testing of different steels and +light alloys for use in engines, and by the end of the War +period a number of aircraft engines were in use of which the +pistons and other parts were of such alloys; the chief +difficulty having been not so much in the design as in the +successful heat-treatment and casting of the metal. + +An important development in connection with the inspection and +testing of aircraft parts, particularly in the case of metal, +was the experimental application of X-ray photography, which +showed up latent defects, both in the material and in +manufacture, which would otherwise have passed unnoticed. This +method was also used to test the penetration of glue into the +wood on each side of joints, so giving a measure of the +strength; and for the effect of 'doping' the wings, dope being a +film (of cellulose acetate dissolved in acetone with other +chemicals) applied to the covering of wings and bodies to render +the linen taut and weatherproof, besides giving it a smooth +surface for the lessening of 'skin friction' when passing rapidly +through the air. + +An important result of this experimental work was that it in +many cases enabled designers to produce aeroplane parts from +less costly material than had previously been considered +necessary, without impairing the strength. It may be mentioned +that it was found undesirable to use welded joints on aircraft +in any part where the material is subjectto a tensile or bending +load, owing to the danger resulting from bad workmanship causing +the material to become brittle--an effect which cannot be +discovered except by cutting through the weld, which, of course, +involves a test to destruction. Written, as it has been, in +August, 1920, it is impossible in this chapter to give any +conception of how the developments of War will be applied to +commercial aeroplanes, as few truly commercial machines have yet +been designed, and even those still show distinct traces of the +survival of war mentality. When, however, the inevitable +recasting of ideas arrives, it will become evident, whatever the +apparent modification in the relative importance of different +aspects of design, that enormous advances were made under the +impetus of War which have left an indelible mark on progress. + +We have, during the seventeen years since aeroplanes first took +the air, seen them grow from tentative experimental structures +of unknown and unknowable performance to highly scientific +products, of which not only the performances (in speed, +load-carrying capacity, and climb) are known, but of which the +precise strength and degree of stability can be forecast with +some accuracy on the drawing board. For the rest, with the +future lies--apart from some revolutionary change in fundamental +design--the steady development of a now well-tried and well-found +engineering structure. + + + +PART III + +AEROSTATICS + +I. BEGINNINGS + +Francesco Lana, with his 'aerial ship,' stands as one of the +first great exponents of aerostatics; up to the time of the +Montgolfier and Charles balloon experiments, aerostatic and +aerodynamic research are so inextricably intermingled that it +has been thought well to treat of them as one, and thus the work +of Lana, Veranzio and his parachute, Guzman's frauds, and the +like, have already been sketched. In connection with Guzman, +Hildebrandt states in his Airships Past and Present, a fairly +exhaustive treatise on the subject up to 1906, the year of its +publication, that there were two inventors--or +charlatans--Lorenzo de Guzman and a monk Bartolemeo Laurenzo, +the former of whom constructed an unsuccessful airship out of a +wooden basket covered with paper, while the latter made certain +experiments with a machine of which no description remains. A +third de Guzman, some twenty-five years later, announced that he +had constructed a flying machine, with which he proposed to fly +from a tower to prove his success to the public. The lack of +record of any fatal accident overtaking him about that time +seems to show that the experiment was not carried out. + +Galien, a French monk, published a book L'art de naviguer dans +l'air in 1757, in which it was conjectured that the air at high +levels was lighter than that immediately over the surface of +the earth. Galien proposed to bring down the upper layers of +air and with them fill a vessel, which by Archimidean principle +would rise through the heavier atmosphere. If one went high +enough, said Galien, the air would be two thousand times as +light as water, and it would be possible to construct an +airship, with this light air as lifting factor, which should be +as large as the town of Avignon, and carry four million +passengers with their baggage. How this high air was to be +obtained is matter for conjecture--Galien seems to have thought +in a vicious circle, in which the vessel that must rise to +obtain the light air must first be filled with it in order to +rise. + +Cavendish's discovery of hydrogen in 1776 set men thinking, and +soon a certain Doctor Black was suggesting that vessels might be +filled with hydrogen, in order that they might rise in the air. +Black, however, did not get beyond suggestion; it was Leo +Cavallo who first made experiments with hydrogen, beginning with +filling soap bubbles, and passing on to bladders and special +paper bags. In these latter the gas escaped, and Cavallo was +about to try goldbeaters' skin at the time that the Montgolfiers +came into the field with their hot air balloon. + +Joseph and Stephen Montgolfier, sons of a wealthy French paper +manufacturer, carried out many experiments in physics, and +Joseph interested himself in the study of aeronautics some time +before the first balloon was constructed by the brothers--he is +said to have made a parachute descent from the roof of his house +as early as 1771, but of this there is no proof. Galien's idea, +together with study of the movement of clouds, gave Joseph some +hope of achieving aerostation through Galien's schemes, and the +first experiments were made by passing steam into a receiver, +which, of course, tended to rise--but the rapid condensation of +the steam prevented the receiver from more than threatening +ascent. The experiments were continued with smoke, which +produced only a slightly better effect, and, moreover, the paper +bag into which the smoke was induced permitted of escape through +its pores; finding this method a failure the brothers desisted +until Priestley's work became known to them, and they conceived +the use of hydrogen as a lifting factor. Trying this with paper +bags, they found that the hydrogen escaped through the pores of +the paper. + +Their first balloon, made of paper, reverted to the hot-air +principle; they lighted a fire of wool and wet straw under the +balloon--and as a matter of course the balloon took fire after +very little experiment; thereupon they constructed a second, +having a capacity of 700 cubic feet, and this rose to a height +of over 1,000 feet. Such a success gave them confidence, and +they gave their first public exhibition on June 5th, 1783, with +a balloon constructed of paper and of a circumference of 112 +feet. A fire was lighted under this balloon, which, after +rising to a height of 1,000 feet, descended through the cooling +of the air inside a matter of ten minutes. At this the Academie +des Sciences invited the brothers to conduct experiments in +Paris. + +The Montgolfiers were undoubtedly first to send up balloons, but +other experimenters were not far behind them, and before they +could get to Paris in response to their invitation, Charles, a +prominent physicist of those days, had constructed a balloon of +silk, which he proofed against escape of gas with rubber--the +Roberts had just succeeded in dissolving this substance to +permit of making a suitable coating for the silk. With a +quarter of a ton of sulphuric acid, and half a ton of iron +filings and turnings, sufficient hydrogen was generated in four +days to fill Charles's balloon, which went up on August 28th, +1783. Although the day was wet, Paris turned out to the number +of over 300,000 in the Champs de Mars, and cannon were fired to +announce the ascent of the balloon. This, rising very rapidly, +disappeared amid the rain clouds, but, probably bursting through +no outlet being provided to compensate for the escape of gas, +fell soon in the neighbourhood of Paris. Here peasants, +ascribing evil supernatural influence to the fall of such a +thing from nowhere, went at it with the implements of their +craft--forks, hoes, and the like--and maltreated it severely, +finally attaching it to a horse's tail and dragging it about +until it was mere rag and scrap. + +Meanwhile, Joseph Montgolfier, having come to Paris, set about +the construction of a balloon out of linen; this was in three +diverse sections, the top being a cone 30 feet in depth, the +middle a cylinder 42 feet in diameter by 26 feet in depth, and +the bottom another cone 20 feet in depth from junction with the +cylindrical portion to its point. The balloon was both lined +and covered with paper, decorated in blue and gold. Before ever +an ascent could be attempted this ambitious balloon was caught +in a heavy rainstorm which reduced its paper covering to pulp +and tore the linen at its seams, so that a supervening strong +wind tore the whole thing to shreds. + +Montgolfier's next balloon was spherical, having a capacity of +52,000 cubic feet. It was made from waterproofed linen, and on +September 19th, 1783, it made an ascent for the palace courtyard +at Versailles, taking up as passengers a cock, a sheep, and a +duck. A rent at the top of the balloon caused it to descend +within eight minutes, and the duck and sheep were found none the +worse for being the first living things to leave the earth in a +balloon, but the cock, evidently suffering, was thought to have +been affected by the rarefaction of the atmosphere at the +tremendous height reached--for at that time the general opinion +was that the atmosphere did not extend more than four or five +miles above the earth's surface. It transpired later that the +sheep had trampled on the cock, causing more solid injury than +any that might be inflicted by rarefied air in an eight-minute +ascent and descent of a balloon. + +For achieving this flight Joseph Montgolfier received from the +King of France a pension of of L40, while Stephen was given +the order of St Michael, and a patent of nobility was granted to +their father. They were made members of the Legion d'Honneur, +and a scientific deputation, of which Faujas de Saint-Fond, who +had raised the funds with which Charles's hydrogen balloon was +constructed, presented to Stephen Montgolfier a gold medal +struck in honour of his aerial conquest. Since Joseph appears +to have had quite as much share in the success as Stephen, the +presentation of the medal to one brother only was in +questionable taste, unless it was intended to balance Joseph's +pension. + +Once aerostation had been proved possible, many people began the +construction of small balloons--the wholehole thing was regarded +as a matter of spectacles and a form of amusement by the great +majority. A certain Baron de Beaumanoir made the first balloon +of goldbeaters' skin, this being eighteen inches in diameter, and +using hydrogen as a lifting factor. Few people saw any +possibilities in aerostation, in spite of the adventures of the +duck and sheep and cock; voyages to the moon were talked and +written, and there was more of levity than seriousness over +ballooning as a rule. The classic retort of Benjamin Franklin +stands as an exception to the general rule: asked what was the +use of ballooning--'What's the use of a baby?' he countered, and +the spirit of that reply brought both the dirigible and the +aeroplane to being, later. + +The next noteworthy balloon was one by Stephen Montgolfier, +designed to take up passengers, and therefore of rather large +dimensions, as these things went then. The capacity was 100,000 +cubic feet, the depth being 85 feet, and the exterior was very +gaily decorated. A short, cylindrical opening was made at the +lower extremity, and under this a fire-pan was suspended, above +the passenger car of the balloon. On October 15th, 1783, +Pilatre de Rozier made the first balloon ascent--but the balloon +was held captive, and only allowed to rise to a height of 80 +feet. But, a little later in 1783, Rozier secured the honour +of making the first ascent in a free balloon, taking up with him +the Marquis d'Arlandes. It had been originally intended that +two criminals, condemned to death, should risk their lives in +the perilous venture, with the prospect of a free pardon if they +made a safe descent, but d'Arlandes got the royal consent to +accompany Rozier, and the criminals lost their chance. Rozier +and d'Arlandes made a voyage lasting for twenty-five minutes, +and, on landing, the balloon collapsed with such rapidity as +almost to suffocate Rozier, who, however, was dragged out to +safety by d'Arlandes. This first aerostatic journey took place +on November 21st, 1783. + +Some seven months later, on June 4th, 1784, a Madame Thible +ascended in a free balloon, reaching a height of 9,000 feet, and +making a journey which lasted for forty-five minutes--the great +King Gustavus of Sweden witnessed this ascent. France grew used +to balloon ascents in the course of a few months, in spite of +the brewing of such a storm as might have been calculated to +wipe out all but purely political interests. Meanwhile, +interest in the new discovery spread across the Channel, and on +September 15th, 1784, one Vincent Lunardi made the first balloon +voyage in England, starting from the Artillery Ground at +Chelsea, with a cat and dog as passengers, and landing in a +field in the parish of Standon, near Ware. There is a rather +rare book which gives a very detailed account of this first +ascent in England, one copy of which is in the library of the +Royal Aeronautical Society; the venturesome Lunardi won a +greater measure of fame through his exploit than did Cody for +his infinitely more courageous and--from a scientific point of +view--valuable first aeroplane ascent in this country. + +The Montgolfier type of balloon, depending on hot air for its +lifting power, was soon realised as having dangerous +limitations. There was always a possibility of the balloon +catching fire while it was being filled, and on landing there +was further danger from the hot pan which kept up the supply of +hot air on the voyage --the collapsing balloon fell on the pan, +inevitably. The scientist Saussure, observing the filling of +the balloons very carefully, ascertained that it was rarefaction +of the air which was responsible for the lifting power, and not +the heat in itself, and, owing to the rarefaction of the air at +normal temperature at great heights above the earth, the limit +of ascent for a balloon of the Montgolfier type was estimated by +him at under 9,000 feet. Moreover, since the amount of fuel +that could be carried for maintaining the heat of the balloon +after inflation was subject to definite limits, prescribed by +the carrying capacity of the balloon, the duration of the +journey was necessarily limited just as strictly. + +These considerations tended to turn the minds of those +interested in aerostation to consideration of the hydrogen +balloon evolved by Professor Charles. Certain improvements had +been made by Charles since his first construction; he employed +rubber-coated silk in the construction of a balloon of 30 feet +diameter, and provided a net for distributing the pressure +uniformly over the surface of the envelope; this net covered the +top half of the balloon, and from its lower edge dependent ropes +hung to join on a wooden ring, from which the car of the balloon +was suspended--apart from the extension of the net so as to +cover in the whole of the envelope, the spherical balloon of +to-day is virtually identical with that of Charles in its method +of construction. He introduced the valve at the top of the +balloon, by which escape of gas could be controlled, operating +his valve by means of ropes which depended to the car of the +balloon, and he also inserted a tube, of about 7 inches +diameter, at the bottom of the balloon, not only for purposes of +inflation, but also to provide a means of escape for gas in case +of expansion due to atmospheric conditions. + +Sulphuric acid and iron filings were used by Charles for filling +his balloon, which required three days and three nights for the +generation of its 14,000 cubic feet of hydrogen gas. The +inflation was completed on December 1st, 1783, and the fittings +carried included a barometer and a grapnel form of anchor. In +addition to this, Charles provided the first 'ballon sonde' in +the form of a small pilot balloon which he handed to Montgolfier +to launch before his own ascent, in order to determine the +direction and velocity of the wind. It was a graceful compliment +to his rival, and indicated that, although they were both working +to the one end, their rivalry was not a matter of bitterness. + +Ascending on December 1st, 1783, Charles took with him one of +the brothers Robert, and with him made the record journey up to +that date, covering a period of three and three-quarter hours, +in which time they journeyed some forty miles. Robert then +landed, and Charles ascended again alone, reaching such a height +as to feel the effects of the rarefaction of the air, this very +largely due to the rapidity of his ascent. Opening the valve at +the top of the balloon, he descended thirty-five minutes after +leaving Robert behind, and came to earth a few miles from the +point of the first descent. His discomfort over the rapid +ascent was mainly due to the fact that, when Robert landed, he +forgot to compensate for the reduction of weight by taking in +further ballast, but the ascent proved the value of the tube at +the bottom of the balloon envelope, for the gas escaped very +rapidly in that second ascent, and, but for the tube, the +balloon must inevitably have burst in the air, with fatal +results for Charles. + +As in the case of aeroplane flight, as soon as the balloon was +proved practicable the flight across the English Channel was +talked of, and Rozier, who had the honour of the first flight, +announced his intention of being first to cross. But Blanchard, +who had an idea for a 'flying car,' anticipated him, and made a +start from Dover on January 7th, 1785, taking with him an +American doctor named Jeffries. Blanchard fitted out his craft +for the journey very thoroughly, taking provisions, oars, and +even wings, for propulsion in case of need. He took so much, in +fact, that as soon as the balloon lifted clear of the ground the +whole of the ballast had to be jettisoned, lest the balloon +should drop into the sea. Half-way across the Channel the +sinking of the balloon warned Blanchard that he had to part with +more than ballast to accomplish the journey, and all the +equipment went, together with certain books and papers that were +on board the car. The balloon looked perilously like +collapsing, and both Blanchard and Jeffries began to undress in +order further to lighten their craft--Jeffries even proposed a +heroic dive to save the situation, but suddenly the balloon rose +sufficiently to clear the French coast, and the two voyagers +landed at a point near Calais in the Forest of Gaines, where a +marble column was subsequently erected to commemorate the great +feat. + +Rozier, although not first across, determined to be second, and +for that purpose he constructed a balloon which was to owe its +buoyancy to a combination of the hydrogen and hot air +principles. There was a spherical hydrogen balloon above, and +beneath it a cylindrical container which could be filled with +hot air, thus compensating for the leakage of gas from the +hydrogen portion of the balloon--regulating the heat of his +fire, he thought, would give him perfect control in the matter of +ascending and descending. + +On July 6th, 1785, a favourable breeze gave Rozier his +opportunity of starting from the French coast, and with a +passenger aboard he cast off in his balloon, which he had named +the 'Aero-Montgolfiere.' There was a rapid rise at first, and +then for a time the balloon remained stationary over the land, +after which a cloud suddenly appeared round the balloon, +denoting that an explosion had taken place. Both Rozier and his +companion were killed in the fall, so that he, first to leave +the earth by balloon, was also first victim to the art of +aerostation. + +There followed, naturally, a lull in the enthusiasm with which +ballooning had been taken up, so far as France was concerned. +In Italy, however, Count Zambeccari took up hot-air ballooning, +using a spirit lamp to give him buoyancy, and on the first +occasion when the balloon car was set on fire Zambeccari let +down his passenger by means of the anchor rope, and managed to +extinguish the fire while in the air. This reduced the buoyancy +of the balloon to such an extent that it fell into the Adriatic +and was totally wrecked, Zambeccari being rescued by fishermen. +He continued to experiment up to 1812, when he attempted to +ascend at Bologna; the spirit in his lamp was upset by the +collision of the car with a tree, and the car was again set on +fire. Zambeccari jumped from the car when it was over fifty feet +above level ground, and was killed. With him the Rozier type of +balloon, combining the hydrogen and hot air principles, +disappeared; the combination was obviously too dangerous to be +practical. + +The brothers Robert were first to note how the heat of the sun +acted on the gases within a balloon envelope, and it has since +been ascertained that sun rays will heat the gas in a balloon to +as much as 80 degrees Fahrenheit greater temperature than the +surrounding atmosphere; hydrogen, being less affected by change +of temperature than coal gas, is the most suitable filling +element, and coal gas comes next as the medium of buoyancy. This +for the free and non-navigable balloon, though for the airship, +carrying means of combustion, and in military work liable to +ignition by explosives, the gas helium seems likely to replace +hydrogen, being non-combustible. + +In spite of the development of the dirigible airship, there +remains work for the free, spherical type of balloon in the +scientific field. Blanchard's companion on the first Channel +crossing by balloon, Dr Jeffries, was the first balloonist to +ascend for purely scientific purposes; as early as 1784 he made +an ascent to a height of 9,000 feet, and observed a fall in +temperature of from degrees--at the level of London, where he +began his ascent--to 29 degrees at the maximum height reached. +He took up an electrometer, a hydrometer, a compass, a +thermometer, and a Toricelli barometer, together with bottles of +water, in order to collect samples of the air at different +heights. In 1785 he made a second ascent, when trigonometrical +observations of the height of the balloon were made from the +French coast, giving an altitude of 4,800 feet. + +The matter was taken up on its scientific side very early in +America, experiments in Philadelphia being almost simultaneous +with those of the Montgolfiers in France. The flight of Rozier +and d'Arlandes inspired two members of the Philadelphia +Philosophical Academy to construct a balloon or series of +balloons of their own design; they made a machine which consisted +of no less than 47 small hydrogen balloons attached to a wicker +car, and made certain preliminary trials, using animals as +passengers. This was followed by a captive ascent with a man as +passenger, and eventually by the first free ascent in America, +which was undertaken by one James Wilcox, a carpenter, on +December 28th, 1783. Wilcox, fearful of falling into a river, +attempted to regulate his landing by cutting slits in some of the +supporting balloons, which was the method adopted for regulating +ascent or descent in this machine. He first cut three, and then, +finding that the effect produced was not sufficient, cut three +more, and then another five--eleven out of the forty-seven. The +result was so swift a descent that he dislocated his wrist on +landing. + + A NOTE ON BALLONETS OR AIR BAGS. + +Meusnier, toward the end of the eighteenth century, was first to +conceive the idea of compensating for the loss of gas due to +expansion by fitting to the interior of a free balloon a +ballonet, or air bag, which could be pumped full of air so as to +retain the shape and rigidity of the envelope. + +The ballonet became particularly valuable as soon as airship +construction became general, and it was in the course of advance +in Astra Torres design that the project was introduced of using +the ballonets in order to give inclination from the horizontal. +In the earlier Astra Torres, trimming was accomplished by moving +the car fore and aft--this in itself was an advance on the +separate 'sliding weigh' principle--and this was the method +followed in the Astra Torres bought by the British Government +from France in 1912 for training airship pilots. Subsequently, +the two ballonets fitted inside the envelope were made to serve +for trimming by the extent of their inflation, and this method of +securing inclination proved the best until exterior rudders, and +greater engine power, supplanted it, as in the Zeppelin and, in +fact, all rigid types. + +In the kite balloon, the ballonet serves the purpose of a +rudder, filling itself through the opening being kept pointed +toward the wind--there is an ingenious type of air scoop with +non-return valve which assures perfect inflation. In the S.S. +type of airship, two ballonets are provided, the supply of air +being taken from the propeller draught by a slanting aluminium +tube to the underside of the envelope, where it meets a +longitudinal fabric hose which connects the two ballonet air +inlets. In this hose the non-return air valves, known as +'crab-pots,' are fitted, on either side of the junction with the +air-scoop. Two automatic air valves, one for each ballonet, are +fitted in the underside of the envelope, and, as the air +pressure tends to open these instead of keeping them shut, the +spring of the valve is set inside the envelope. Each spring is +set to open at a pressure of 25 to 28 mm. + + + +II. THE FIRST DIRIGIBLES + +Having got off the earth, the very early balloonists set about +the task of finding a means of navigating the air but, lacking +steam or other accessory power to human muscle, they failed to +solve the problem. Joseph Montgolfier speedily exploded the +idea of propelling a balloon either by means of oars or sails, +pointing out that even in a dead calm a speed of five miles an +hour would be the limit achieved. Still, sailing balloons were +constructed, even up to the time of Andree, the explorer, who +proposed to retard the speed of the balloon by ropes dragging on +the ground, and then to spread a sail which should catch the +wind and permit of deviation of the course. It has been proved +that slight divergences from the course of the wind can be +obtained by this means, but no real navigation of the air could +be thus accomplished. + +Professor Wellner, of Brunn, brought up the idea of a sailing +balloon in more practical fashion in 1883. He observed that +surfaces inclined to the horizontal have a slight lateral motion +in rising and falling, and deduced that by alternate lowering +and raising of such surfaces he would be able to navigate the +air, regulating ascent and descent by increasing or decreasing +the temperature of his buoyant medium in the balloon. He +calculated that a balloon, 50 feet in diameter and 150 feet in +length, with a vertical surface in front and a horizontal +surface behind, might be navigated at a speed of ten miles per +hour, and in actual tests at Brunn he proved that a single rise +and fall moved the balloon three miles against the wind. His +ideas were further developed by Lebaudy in the construction of +the early French dirigibles. + +According to Hildebrandt,[*] the first sailing balloon was built +in 1784 by Guyot, who made his balloon egg-shaped, with the +smaller end at the back and the longer axis horizontal; oars +were intended to propel the craft, and naturally it was a +failure. Carra proposed the use of paddle wheels, a step in the +right direction, by mounting them on the sides of the car, but +the improvement was only slight. Guyton de Morveau, entrusted +by the Academy of Dijon with the building of a sailing balloon, +first used a vertical rudder at the rear end of his +construction--it survives in the modern dirigible. His +construction included sails and oars, but, lacking steam or +other than human propulsive power, the airship was a failure +equally with Guyot's. + +[*] Airships Past and Present. + +Two priests, Miollan and Janinet, proposed to drive balloons +through the air by the forcible expulsion of the hot air in the +envelope from the rear of the balloon. An opening was made +about half-way up the envelope, through which the hot air was to +escape, buoyancy being maintained by a pan of combustibles in +the car. Unfortunately, this development of the Montgolfier type +never got a trial, for those who were to be spectators of the +first flight grew exasperated at successive delays, and in the +end, thinking that the balloon would never rise, they destroyed +it. + +Meusnier, a French general, first conceived the idea of +compensating for loss of gas by carrying an air bag inside the +balloon, in order to maintain the full expansion of the +envelope. The brothers Robert constructed the first balloon in +which this was tried and placed the air bag near the neck of the +balloon which was intended to be driven by oars, and steered by +a rudder. A violent swirl of wind which was encountered on the +first ascent tore away the oars and rudder and broke the ropes +which held the air bag in position; the bag fell into the +opening of the neck and stopped it up, preventing the escape of +gas under expansion. The Duc de Chartres, who was aboard, +realised the extreme danger of the envelope bursting as the +balloon ascended, and at 16,000 feet he thrust a staff through +the envelope--another account says that he slit it with his +sword--and thus prevented disaster. The descent after this rip +in the fabric was swift, but the passengers got off without +injury in the landing. + +Meusnier, experimenting in various ways, experimented with +regard to the resistance offered by various shapes to the air, +and found that an elliptical shape was best; he proposed to make +the car boat--shaped, in order further to decrease the +resistance, and he advocated an entirely rigid connection +between the car and the body of the balloon, as indispensable to +a dirigible.[*] He suggested using three propellers, which were +to be driven by hand by means of pulleys, and calculated that a +crew of eighty would be required to furnish sufficient motive +power. Horizontal fins were to be used to assure stability, and +Meusnier thoroughly investigated the pressures exerted by gases, +in order to ascertain the stresses to which the envelope would be +subjected. More important still, he went into detail with +regard to the use of air bags, in order to retain the shape of +the balloon under varying pressures of gas due to expansion and +consequent losses; he proposed two separate envelopes, the inner +one containing gas, and the space between it and the outer one +being filled with air. Further, by compressing the air inside +the air bag, the rate of ascent or descent could be regulated. +Lebaudy, acting on this principle, found it possible to pump air +at the rate of 35 cubic feet per second, thus making good loss +of ballast which had to be thrown overboard. + +[*] Hildebrandt. + +Meusnier's balloon, of course, was never constructed, but his +ideas have been of value to aerostation up to the present time. +His career ended in the revolutionary army in 1793, when he was +killed in the fighting before Mayence, and the King of Prussia +ordered all firing to cease until Meusnier had been buried. No +other genius came forward to carry on his work, and it was +realised that human muscle could not drive a balloon with +certainty through the air; experiment in this direction was +abandoned for nearly sixty years, until in 1852 Giffard +brought the first practicable power-driven dirigible to being. + +Giffard, inventor of the steam injector, had already made +balloon ascents when he turned to aeronautical propulsion, and +constructed a steam engine of 5 horsepower with a weight of only +100 lbs.--a great achievement for his day. Having got his +engine, he set about making the balloon which it was to drive; +this he built with the aid of two other enthusiasts, diverging +from Meusnier's ideas by making the ends pointed, and keeping the +body narrowed from Meusnier's ellipse to a shape more resembling +a rather fat cigar. The length was 144 feet, and the greatest +diameter only 40 feet, while the capacity was 88,000 cubic feet. +A net which covered the envelope of the balloon supported a +spar, 66 feet in length, at the end of which a triangular sail +was placed vertically to act as rudder. The car, slung 20 feet +below the spar, carried the engine and propeller. Engine and +boiler together weighed 350 lbs., and drove the 11 foot +propeller at 110 revolutions per minute. + +As precaution against explosion, Giffard arranged wire gauze in +front of the stoke-hole of his boiler, and provided an exhaust +pipe which discharged the waste gases from the engine in a +downward direction. With this first dirigible he attained to a +speed of between 6 and 8 feet per second, thus proving that the +propulsion of a balloon was a possibility, now that steam had +come to supplement human effort. + +Three years later he built a second dirigible, reducing the +diameter and increasing the length of the gas envelope, with a +view to reducing air resistance. The length of this was 230 +feet, the diameter only 33 feet, and the capacity was 113,000 +cubic feet, while the upper part of the envelope, to which the +covering net was attached, was specially covered to ensure a +stiffening effect. The car of this dirigible was dropped rather +lower than that of the first machine, in order to provide more +thoroughly against the danger of explosions. Giffard, with a +companion named Yon as passenger, took a trial trip on this +vessel, and made a journey against the wind, though slowly. In +commencing to descend, the nose of the envelope tilted upwards, +and the weight of the car and its contents caused the net to +slip, so that just before the dirigible reached the ground, the +envelope burst. Both Giffard and his companion escaped with very +slight injuries. + +Plans were immediately made for the construction of a third +dirigible, which was to be 1,970 feet in length, 98 feet in +extreme diameter, and to have a capacity of 7,800,000 cubic feet +of gas. The engine of this giant was to have weighed 30 tons, +and with it Giffard expected to attain a speed of 40 miles per +hour. Cost prevented the scheme being carried out, and Giffard +went on designing small steam engines until his invention of the +steam injector gave him the funds to turn to dirigibles again. +He built a captive balloon for the great exhibition in London in +1868, at a cost of nearly L30,000, and designed a dirigible +balloon which was to have held a million and three quarters +cubic feet of gas, carry two boilers, and cost about L40,000. +The plans were thoroughly worked out, down to the last detail, +but the dirigible was never constructed. Giffard went blind, and +died in 1882--he stands as the great pioneer of dirigible +construction, more on the strength of the two vessels which he +actually built than on that of the ambitious later conceptions +of his brain. + +In 1872 Dupuy de Lome, commissioned by the French government, +built a dirigible which he proposed to drive by man-power--it +was anticipated that the vessel would be of use in the siege of +Paris, but it was not actually tested till after the conclusion +of the war. The length of this vessel was 118 feet, its +greatest diameter 49 feet, the ends being pointed, and the +motive power was by a propeller which was revolved by the +efforts of eight men. The vessel attained to about the same +speed as Giffard's steam-driven airship; it was capable of +carrying fourteen men, who, apart from these engaged in driving +the propeller, had to manipulate the pumps which controlled the +air bags inside the gas envelope. + +In the same year Paul Haenlein, working in Vienna, produced an +airship which was a direct forerunner of the Lebaudy type, 164 +feet in length, 30 feet greatest diameter, and with a cubic +capacity of 85,000 feet. Semi-rigidity was attained by placing +the car as close to the envelope as possible, suspending it by +crossed ropes, and the motive power was a gas engine of the +Lenoir type, having four horizontal cylinders, and giving about +5 horse-power with a consumption of about 250 cubic feet of gas +per hour. This gas was sucked from the envelope of the balloon, +which was kept fully inflated by pumping in compensating air to +the air bags inside the main envelope. A propeller, 15 feet in +diameter, was driven by the Lenoir engine at 40 revolutions per +minute. This was the first instance of the use of an internal +combustion engine in connection with aeronautical experiments. + +The envelope of this dirigible was rendered airtight by means of +internal rubber coating, with a thinner film on the outside. +Coal gas, used for inflation, formed a suitable fuel for the +engine, but limited the height to which the dirigible could +ascend. Such trials as were made were carried out with the +dirigible held captive, and a speed of I 5 feet per second was +attained. Full experiment was prevented through funds running +low, but Haenlein's work constituted a distinct advance on all +that had been done previously. + +Two brothers, Albert and Gaston Tissandier, were next to enter +the field of dirigible construction; they had experimented with +balloons during the Franc-Prussian War, and had attempted to get +into Paris by balloon during the siege, but it was not until +1882 that they produced their dirigible. + +This was 92 feet in length and 32 feet in greatest diameter, +with a cubic capacity of 37,500 feet, and the fabric used was +varnished cambric. The car was made of bamboo rods, and in +addition to its crew of three, it carried a Siemens dynamo, with +24 bichromate cells, each of which weighed 17 lbs. The motor +gave out 1 1/2 horse-power, which was sufficient to drive the +vessel at a speed of up to 10 feet per second. This was not so +good as Haenlein's previous attempt and, after L2,000 had been +spent, the Tissandier abandoned their experiments, since a 5-mile +breeze was sufficient to nullify the power of the motor. + +Renard, a French officer who had studied the problem of +dirigible construction since 1878, associated himself first with +a brother officer named La Haye, and subsequently with another +officer, Krebs, in the construction of the second dirigible to +be electrically-propelled. La Haye first approached Colonel +Laussedat, in charge of the Engineers of the French Army, with a +view to obtaining funds, but was refused, in consequence of the +practical failure of all experiments since 1870. Renard, with +whom Krebs had now associated himself, thereupon went to +Gambetta, and succeeded in getting a promise of a grant of +L8,000 for the work; with this promise Renard and Krebs set to +work. + +They built their airship in torpedo shape, 165 feet in length, +and of just over 27 feet greatest diameter--the greatest diameter +was at the front, and the cubic capacity was 66,000 feet. The +car itself was 108 feet in length, and 4 1/2 feet broad, covered +with silk over the bamboo framework. The 23 foot diameter +propeller was of wood, and was driven by an electric motor +connected to an accumulator, and yielding 8.5 horsepower. The +sweep of the propeller, which might have brought it in contact +with the ground in landing, was counteracted by rendering it +possible to raise the axis on which the blades were mounted, and +a guide rope was used to obviate damage altogether, in case of +rapid descent. There was also a 'sliding weight' which was +movable to any required position to shift the centre of gravity +as desired. Altogether, with passengers and ballast aboard, the +craft weighed two tons. + +In the afternoon of August 8th, 1884, Renard and Krebs ascended +in the dirigible--which they had named 'La France,' from the +military ballooning ground at Chalais-Meudon, making a circular +flight of about five miles, the latter part of which was in the +face of a slight wind. They found that the vessel answered well +to her rudder, and the five-mile flight was made successfully in +a period of 23 minutes. Subsequent experimental flights +determined that the air speed of the dirigible was no less than +14 1/2 miles per hour, by far the best that had so far been +accomplished in dirigible flight. Seven flights in all were +made, and of these five were completely successful, the +dirigible returning to its starting point with no difficulty. On +the other two flights it had to be towed back. + +Renard attempted to repeat his construction on a larger scale, +but funds would not permit, and the type was abandoned; the +motive power was not sufficient to permit of more than short +flights, and even to the present time electric motors, with +their necessary accumulators, are far too cumbrous to compete +with the self-contained internal combustion engine. France had +to wait for the Lebaudy brothers, just as Germany had to wait +for Zeppelin and Parseval. + +Two German experimenters, Baumgarten and Wolfert, fitted a +Daimler motor to a dirigible balloon which made its first ascent +at Leipzig in 1880. This vessel had three cars, and placing a +passenger in one of the outer cars[*] distributed the load +unevenly, so that the whole vessel tilted over and crashed to +the earth, the occupants luckily escaping without injury. After +Baumgarten's death, Wolfert determined to carry on with his +experiments, and, having achieved a certain measure of success, +he announced an ascent to take place on the Tempelhofer Field, +near Berlin, on June 12th, 1897. The vessel, travelling with +the wind, reached a height of 600 feet, when the exhaust of the +motor communicated flame to the envelope of the balloon, and +Wolfert, together with a passenger he carried, was either killed +by the fall or burnt to death on the ground. Giffard had taken +special precautions to avoid an accident of this nature, and +Wolfert, failing to observe equal care, paid the full penalty. + +[*] Hildebrandt. + +Platz, a German soldier, attempting an ascent on the Tempelhofer +Field in the Schwartz airship in 1897, merely proved the +dirigible a failure. The vessel was of aluminium, 0.008 inch +in thickness, strengthened by an aluminium lattice work; the +motor was two-cylindered petrol-driven; at the first trial the +metal developed such leaks that the vessel came to the ground +within four miles of its starting point. Platz, who was aboard +alone as crew, succeeded in escaping by jumping clear before the +car touched earth, but the shock of alighting broke up the +balloon, and a following high wind completed the work of full +destruction. A second account says that Platz, finding the +propellers insufficient to drive the vessel against the wind, +opened the valve and descended too rapidly. + +The envelope of this dirigible was 156 feet in length, and the +method of filling was that of pushing in bags, fill them with +gas, and then pulling them to pieces and tearing them out of the +body of the balloon. A second contemplated method of filling +was by placing a linen envelope inside the aluminium casing, +blowing it out with air, and then admitting the gas between the +linen and the aluminium outer casing. This would compress the +air out of the linen envelope, which was to be withdrawn when +the aluminium casing had been completely filled with gas. + +All this, however, assumes that the Schwartz type--the first +rigid dirigible, by the way--would prove successful. As it +proved a failure on the first trial, the problem of filling it +did not arise again. + +By this time Zeppelin, retired from the German army, had begun +to devote himself to the study of dirigible construction, and, a +year after Schwartz had made his experiment and had failed, he +got together sufficient funds for the formation of a +limitedliability company, and started on the construction of the +first of his series of airships. The age of tentative +experiment was over, and, forerunner of the success of the +heavier-than-air type of flying machine, successful dirigible +flight was accomplished by Zeppelin in Germany, and by +Santos-Dumont in France. + + + +III. SANTOS-DUMONT + +A Brazilian by birth, Santos-Dumont began in Paris in the year +1898 to make history, which he subsequently wrote. His book, My +Airships, is a record of his eight years of work on +lighter-than-air machines, a period in which he constructed no +less than fourteen dirigible balloons, beginning with a cubic +capacity of 6,350 feet, and an engine of 3 horse-power, and +rising to a cubic capacity of 71,000 feet on the tenth dirigible +he constructed, and an engine of 60 horse-power, which was +fitted to the seventh machine in order of construction, the one +which he built after winning the Deutsch Prize. + +The student of dirigible construction is recommended to +Santos-Dumont's own book not only as a full record of his work, +but also as one of the best stories of aerial navigation that +has ever been written. Throughout all his experiments, he +adhered to the non-rigid type; his first dirigible made its +first flight on September 18th, 1898, starting from the Jardin +d'Acclimatation to the west of Paris; he calculated that his 3 +horse-power engine would yield sufficient power to enable him to +steer clear of the trees with which the starting-point was +surrounded, but, yielding to the advice of professional +aeronauts who were present, with regard to the placing of the +dirigible for his start, he tore the envelope against the trees. +Two days later, having repaired the balloon, he made an ascent of +1,300 feet. In descending, the hydrogen left in the balloon +contracted, and Santos-Dumont narrowly escaped a serious accident +in coming to the ground. + +His second machine, built in the early spring of 1899, held over +7,000 cubic feet of gas and gave a further 44 lbs. of ascensional +force. The balloon envelope was very long and very narrow; the +first attempt at flight was made in wind and rain, and the +weather caused sufficient contraction of the hydrogen for a wind +gust to double the machine up and toss it into the trees near its +starting-point. The inventor immediately set about the +construction of 'Santos-Dumont No. 3,' on which he made a number +of successful flights, beginning on November 13th, 1899. On the +last of his flights, he lost the rudder of the machine and made a +fortunate landing at Ivry. He did not repair the balloon, +considering it too clumsy in form and its motor too small. +Consequently No. 4 was constructed, being finished on the 1st, +August, 1900. It had a cubic capacity of 14,800 feet, a length +of 129 feet and greatest diameter of 16.7 feet, the power +plant being a 7 horse-power Buchet motor. Santos-Dumont sat on +a bicycle saddle fixed to the long bar suspended under the +machine, which also supported motor propeller, ballast; and +fuel. The experiment of placing the propeller at the stem +instead of at the stern was tried, and the motor gave it a speed +of 100 revolutions per minute. Professor Langley witnessed the +trials of the machine, which proved before the members of the +International Congress of Aeronautics, on September 19th, that +it was capable of holding its own against a strong wind. + +Finding that the cords with which his dirigible balloon cars were +suspended offered almost as much resistance to the air as did +the balloon itself, Santos-Dumont substituted piano wire and +found that the alteration constituted greater progress than many +a more showy device. He altered the shape and size of his No. 4 +to a certain extent and fitted a motor of 12 horse-power. +Gravity was controlled by shifting weights worked by a cord; +rudder and propeller were both placed at the stern. In +Santos-Dumont's book there is a certain amount of confusion +between the No. 4 and No. 5 airships, until he explains that +'No. 5' is the reconstructed 'No. 4.' It was with No. 5 that +he won the Encouragement Prize presented by the Scientific +Commission of the Paris Aero Club. This he devoted to the first +aeronaut who between May and October of 1900 should start from +St Cloud, round the Eiffel Tower, and return. If not won in +that year, the prize was to remain open the following year from +May 1st to October 1st, and so on annually until won. This was a +simplification of the conditions of the Deutsch Prize itself, the +winning of which involved a journey of 11 kilometres in 30 +minutes. + +The Santos-Dumont No. 5, which was in reality the modified No. 4 +with new keel, motor, and propeller, did the course of the +Deutsch Prize, but with it Santos-Dumont made no attempt to win +the prize until July of 1901, when he completed the course in 40 +minutes, but tore his balloon in landing. On the 8th August, +with his balloon leaking, he made a second attempt, and narrowly +escaped disaster, the airship being entirely wrecked. Thereupon +he built No. 6 with a cubic capacity of 22,239 feet and a lifting +power of 1,518 lbs. + +With this machine he won the Deutsch Prize on October 19th, +1901, starting with the disadvantage of a side wind of 20 feet +per second. He reached the Eiffel Tower in 9 minutes and, +through miscalculating his turn, only just missed colliding +with it. He got No. 6 under control again and succeeded in +getting back to his starting-point in 29 1/2 minutes, thus +winning the 125,000 francs which constituted the Deutsch Prize, +together with a similar sum granted to him by the Brazilian +Government for the exploit. The greater part of this money was +given by Santos-Dumont to charities. + +He went on building after this until he had made fourteen +non-rigid dirigibles; of these No. 12 was placed at the disposal +of the military authorities, while the rest, except for one that +was sold to an American and made only one trip, were matters of +experiment for their maker. His conclusions from his experiments +may be gathered from his own work:-- + +'On Friday, 31st July, 1903, Commandant Hirschauer and +Lieutenant-Colonel Bourdeaux spent the afternoon with me at my +airship station at Neuilly St James, where I had my three newest +airships--the racing 'No. 7,' the omnibus 'No. 10,' and the +runabout 'No. 9'--ready for their study. Briefly, I may say +that the opinions expressed by the representatives of the +Minister of War were so unreservedly favourable that a practical +test of a novel character was decided to be made. Should the +airship chosen pass successfully through it the result will be +conclusive of its military value. + +'Now that these particular experiments are leaving my exclusively +private control I will say no more of them than what has been +already published in the French press. The test will probably +consist of an attempt to enter one of the French frontier towns, +such as Belfort or Nancy, on the same day that the airship +leaves Paris. It will not, of course, be necessary to make the +whole journey in the airship. A military railway wagon may be +assigned to carry it, with its balloon uninflated, with tubes of +hydrogen to fill it, and with all the necessary machinery and +instruments arranged beside it. At some station a short +distance from the town to be entered the wagon may be uncoupled +from the train, and a sufficient number of soldiers accompanying +the officers will unload the airship and its appliances, +transport the whole to the nearest open space, and at once begin +inflating the balloon. Within two hours from quitting the train +the airship may be ready for its flight to the interior of the +technically-besieged town. + +'Such may be the outline of the task--a task presented +imperiously to French balloonists by the events of 1870-1, and +which all the devotion and science of the Tissandier brothers +failed to accomplish. To-day the problem may be set with better +hope of success. All the essential difficulties may be revived +by the marking out of a hostile zone around the town that must +be entered; from beyond the outer edge of this zone, then, the +airship will rise and take its flight--across it. + +'Will the airship be able to rise out of rifle range? I have +always been the first to insist that the normal place of the +airship is in low altitudes, and I shall have written this book +to little purpose if I have not shown the reader the real +dangers attending any brusque vertical mounting to considerable +heights. For this we have the terrible Severo accident before +our eyes. In particular, I have expressed astonishment at +hearing of experimenters rising to these altitudes without +adequate purpose in their early stages of experience with +dirigible balloons. All this is very different, however, from a +reasoned, cautious mounting, whose necessity has been foreseen +and prepared for.' + +Probably owing to the fact that his engines were not of +sufficient power, Santos-Dumont cannot be said to have solved +the problem of the military airship, although the French +Government bought one of his vessels. At the same time, he +accomplished much in furthering and inciting experiment with +dirigible airships, and he will always rank high among the +pioneers of aerostation. His experiments might have gone +further had not the Wright brothers' success in America and +French interest in the problem of the heavier-than-air machine +turned him from the study of dirigibles to that of the +aeroplane, in which also he takes high rank among the pioneers, +leaving the construction of a successful military dirigible to +such men as the Lebaudy brothers, Major Parseval, and Zeppelin. + + + +IV. THE MILITARY DIRIGIBLE + +Although French and German experiment in connection with the +production of an airship which should be suitable for military +purposes proceeded side by side, it is necessary to outline the +development in the two countries separately, owing to the +differing character of the work carried out. So far as France +is concerned, experiment began with the Lebaudy brothers, +originally sugar refiners, who turned their energies to airship +construction in 1899. Three years of work went to the production +of their first vessel, which was launched in 1902, having been +constructed by them together with a balloon manufacturer named +Surcouf and an engineer, Julliot. The Lebaudy airships were +what is known as semi-rigids, having a spar which ran +practically the full length of the gas bag to which it was +attached in such a way as to distribute the load evenly. The +car was suspended from the spar, at the rear end of which both +horizontal and vertical rudders were fixed, whilst stabilising +fins were provided at the stern of the gas envelope itself. The +first of the Lebaudy vessels was named the 'Jaune'; its length +was 183 feet and its maximum diameter 30 feet, while the cubic +capacity was 80,000 feet. The power unit was a 40 horse-power +Daimler motor, driving two propellers and giving a maximum speed +of 26 miles per hour. This vessel made 29 trips, the last of +which took place in November, 1902, when the airship was wrecked +through collision with a tree. + +The second airship of Lebaudy construction was 7 feet longer +than the first, and had a capacity of 94,000 cubic feet of gas +with a triple air bag of 17,500 cubic feet to compensate for +loss of gas; this latter was kept inflated by a rotary fan. The +vessel was eventually taken over by the French Government and +may be counted the first dirigible airship considered fit on its +tests for military service. + +Later vessels of the Lebaudy type were the 'Patrie' and +'Republique,' in which both size and method of construction +surpassed those of the two first attempts. The 'Patrie' was +fitted with a 60 horse-power engine which gave a speed of 28 +miles an hour, while the vessel had a radius of 280 miles, +carrying a crew of nine. In the winter of 1907 the 'Patrie' was +anchored at Verdun, and encountered a gale which broke her hold +on her mooring-ropes. She drifted derelict westward across +France, the Channel, and the British Isles, and was lost in the +Atlantic. + +The 'Republique' had an 80 horse-power motor, which, however, +only gave her the same speed as the 'Patrie.' She was launched +in July, 1908, and within three months came to an end which +constituted a tragedy for France. A propeller burst while the +vessel was in the air, and one blade, flying toward the +envelope, tore in it a great gash; the airship crashed to earth, +and the two officers and two non-commissioned officers who were +in the car were instantaneously killed. + +The Clement Bayard, and subsequently the Astra-Torres, +non-rigids, followed on the early Lebaudys and carried French +dirigible construction up to 1912. The Clement Bayard was a +simple non-rigid having four lobes at the stern end to assist +stability. These were found to retard the speed of the airship, +which in the second and more successful construction was driven +by a Clement Bayard motor of l00 horse-power at a speed of 30 +miles an hour. On August 23rd, 1909, while being tried for +acceptance by the military authorities, this vessel achieved a +record by flying at a height of 5,000 feet for two hours. The +Astra-Torres non-rigids were designed by a Spaniard, Senor +Torres, and built by the Astra Company. The envelope was of +trefoil shape, this being due to the interior rigging from the +suspension band; the exterior appearance is that of two lobes +side by side, overlaid by a third. The interior rigging, which +was adopted with a view to decreasing air resistance, supports a +low-hung car from the centre of the envelope; steering is +accomplished by means of horizontal planes fixed on the envelope +at the stern, and vertical planes depending beneath the envelope, +also at the stern end. + +One of the most successful of French pre-war dirigibles was a +Clement Bayard built in 1912. In this twin propellers were +placed at the front and horizontal and vertical rudders in a +sort of box formation under the envelope at the stern. The +envelope was stream-lined, while the car of the machine was +placed well forward with horizontal controlling planes above it +and immediately behind the propellers. This airship, which was +named 'Dupuy de Lome,' may be ranked as about the most +successful non-rigid dirigible constructed prior to the War. + +Experiments with non-rigids in Germany was mainly carried on by +Major Parseval, who produced his first vessel in 1906. The main +feature of this airship consisted in variation in length of the +suspension cables at the will of the operator, so that the +envelope could be given an upward tilt while the car remained +horizontal in order to give the vessel greater efficiency in +climbing. In this machine, the propeller was placed above and +forward of the car, and the controlling planes were fixed +directly to the envelope near the forward end. A second vessel +differed from the first mainly in the matter of its larger size, +variable suspension being again employed, together with a similar +method of control. The vessel was moderately successful, and +under Major Parseval's direction a third was constructed for +passenger carrying, with two engines of 120 horsepower, each +driving propellers of 13 feet diameter. This was the most +successful of the early German dirigibles; it made a number of +voyages with a dozen passengers in addition to its crew, as well +as proving its value for military purposes by use as a scout +machine in manoeuvres. Later Parsevals were constructed of +stream-line form, about 300 feet in length, and with engines +sufficiently powerful to give them speeds up to 50 miles an hour. + +Major Von Gross, commander of a Balloon Battalion, produced +semi-rigid dirigibles from 1907 onward. The second of these, +driven by two 75 horse-power Daimler motors, was capable of a +speed of 27 miles an hour; in September of 1908 she made a trip +from and back to Berlin which lasted 13 hours, in which period +she covered 176 miles with four passengers and reached a height +of 4,000 feet. Her successor, launched in April of 1909, +carried a wireless installation, and the next to this, driven by +four motors of 75 horse-power each, reached a speed of 45 miles +an hour. As this vessel was constructed for military purposes, +very few details either of its speed or method of construction +were made public. + +Practically all these vessels were discounted by the work of +Ferdinand von Zeppelin, who set out from the first with the idea +of constructing a rigid dirigible. Beginning in 1898, he built a +balloon on an aluminium framework covered with linen and silk, +and divided into interior compartments holding linen bags which +were capable of containing nearly 400,000 cubic feet of +hydrogen. The total length of this first Zeppelin airship was +420 feet and the diameter 38 feet. Two cars were rigidly +attached to the envelope, each carrying a 16 horse-power motor, +driving propellers which were rigidly connected to the aluminium +framework of the balloon. Vertical and horizontal screws were +used for lifting and forward driving and a sliding weight was +used to raise or lower the stem of the vessel out of the +horizontal in order to rise or descend without altering the load +by loss of ballast or the lift by loss of gas. + +The first trial of this vessel was made in July of 1900, and was +singularly unfortunate. The winch by which the sliding weight +was operated broke, and the balloon was so bent that the working +of the propellers was interfered with, as was the steering. A +speed of 13 feet per second was attained, but on descending, the +airship ran against some piles and was further damaged. Repairs +were completed by the end of September, 1900, and on a second +trial flight made on October 21st a speed of 30 feet per second +was reached. + +Zeppelin was far from satisfied with the performance of this +vessel, and he therefore set about collecting funds for the +construction of a second, which was completed in 1905. By this +time the internal combustion engine had been greatly improved, +and without any increase of weight, Zeppelin was able to instal +two motors of 85 horse-power each. The total capacity was +367,000 cubic feet of hydrogen, carried in 16 gas bags inside +the framework, and the weight of the whole construction was 9 +tons--a ton less than that of the first Zeppelin airship. Three +vertical planes at front and rear controlled horizontal +steering, while rise and fall was controlled by horizontal +planes arranged in box form. Accident attended the first trial +of this second airship, which took place over the Bodensee on +November 30th, 1905, 'It had been intended to tow the raft, to +which it was anchored, further from the shore against the wind. +But the water was too low to allow the use of the raft. The +balloon was therefore mounted on pontoons, pulled out into the +lake, and taken in tow by a motor-boat. It was caught by a +strong wind which was blowing from the shore, and driven ahead +at such a rate that it overtook the motor-boat. The tow rope +was therefore at once cut, but it unexpectedly formed into knots +and became entangled with the airship, pulling the front end +down into the water. The balloon was then caught by the wind +and lifted into the air, when the propellers were set in motion. +The front end was at this instant pointing in a downward +direction, and consequently it shot into the water, where it was +found necessary to open the valves.'[*] + +[*] Hildebrandt, Airships Past and Present. + +The damage done was repaired within six weeks, and the second +trial was made on January 17th, 1906. The lifting force was too +great for the weight, and the dirigible jumped immediately to +1,500 feet. The propellers were started, and the dirigible +brought to a lower level, when it was found possible to drive +against the wind. The steering arrangements were found too +sensitive, and the motors were stopped, when the vessel was +carried by the wind until it was over land--it had been intended +that the trial should be completed over water. A descent was +successfully accomplished and the dirigible was anchored for the +night, but a gale caused it so much damage that it had to be +broken up. It had achieved a speed of 30 feet per second with +the motors developing only 36 horse-power and, gathering from +this what speed might have been accomplished with the full 170 +horse-power, Zeppelin set about the construction of No. 3, with +which a number of successful voyages were made, proving the value +of the type for military purposes. + +No. 4 was the most notable of the early Zeppelins, as much on +account of its disastrous end as by reason of any superior merit +in comparison with No. 3. The main innovation consisted in +attaching a triangular keel to the under side of the envelope, +with two gaps beneath which the cars were suspended. Two Daimler +Mercedes motors of 110 horse-power each were placed one in each +car, and the vessel carried sufficient fuel for a 60-hour cruise +with the motors running at full speed. Each motor drove a pair +of three-bladed metal propellers rigidly attached to the +framework of the envelope and about 15 feet in diameter. There +was a vertical rudder at the stern of the envelope and horizontal +controlling planes were fixed on the sides of the envelope. The +best performances and the end of this dirigible were summarised +as follows by Major Squier:-- + +'Its best performances were two long trips performed during the +summer of 1908. The first, on July 4th, lasted exactly 12 +hours, during which time it covered a distance of 235 miles, +crossing the mountains to Lucerne and Zurich, and returning to +the balloon-house near Friedrichshafen, on Lake Constance. The +average speed on this trip was 32 miles per hour. On August +4th, this airship attempted a 24-hour flight, which was one of +the requirements made for its acceptance by the Government. It +left Friedrichshafen in the morning with the intention of +following the Rhine as far as Mainz, and then returning to its +starting-point, straight across the country. A stop of 3 hours +30 minutes was made in the afternoon of the first day on the +Rhine, to repair the engine. On the return, a second stop was +found necessary near Stuttgart, due to difficulties with the +motors, and some loss of gas. While anchored to the ground, a +storm arose which broke loose the anchorage, and, as the balloon +rose in the air, it exploded and took fire (due to causes which +have never been actually determined and published) and fell to +the ground, where it was completely destroyed. On this journey, +which lasted in all 31 hours 15 minutes, the airship was in the +air 20 hours 45 minutes, and covered a total distance of 378 +miles. + +'The patriotism of the German nation was aroused. Subscriptions +were immediately started, and in a short space of time a quarter +of a million pounds had been raised. A Zeppelin Society was +formed to direct the expenditure of this fund. Seventeen +thousand pounds has been expended in purchasing land near +Friedrichshafen; workshops were erected, and it was announced +that within one year the construction of eight airships of the +Zeppelin type would be completed. Since the disaster to +'Zeppelin IV.' the Crown Prince of Germany made a trip in +'Zeppelin No. 3,' which had been called back into service, and +within a very few days the German Emperor visited Friedrichshafen +for the purpose of seeing the airship in flight. He decorated +Count Zeppelin with the order of the Black Eagle. German +patriotism and enthusiasm has gone further, and the "German +Association for an Aerial Fleet" has been organised in +sections throughout the country. It announces its intention of +building 50 garages (hangars) for housing airships.' + +By January of 1909, with well over a quarter of a million in +hand for the construction of Zeppelin airships, No. 3 was again +brought out, probably in order to maintain public enthusiasm in +respect of the possible new engine of war. In March of that +year No. 3 made a voyage which lasted for 4 hours over and in +the vicinity of Lake Constance; it carried 26 passengers for a +distance of nearly 150 miles. + +Before the end of March, Count Zeppelin determined to voyage +from Friedrichshafen to Munich, together with the crew of the +airship and four military officers. Starting at four in the +morning and ascertaining their route from the lights of railway +stations and the ringing of bells in the towns passed over, the +journey was completed by nine o'clock, but a strong south-west +gale prevented the intended landing. The airship was driven +before the wind until three o'clock in the afternoon, when it +landed safely near Dingolfing; by the next morning the wind had +fallen considerably and the airship returned to Munich and +landed on the parade ground as originally intended. At about +3.30 in the afternoon, the homeward journey was begun, +Friedrichshafen being reached at about 7.30. + +These trials demonstrated that sufficient progress had been made +to justify the construction of Zeppelin airships for use with +the German army. No. 3 had been manoeuvred safely if not +successfully in half a gale of wind, and henceforth it was known +as 'SMS. Zeppelin I.,' at the bidding of the German Emperor, +while the construction of 'SMS. Zeppelin II.' was rapidly +proceeded with. The fifth construction of Count Zeppelin's was +446 feet in length, 42 1/2 feet in diameter, and contained +530,000 cubic feet of hydrogen gas in 17 separate compartments. +Trial flights were made on the 26th May, 1909, and a week later +she made a record voyage of 940 miles, the route being from Lake +Constance over Ulm, Nuremberg, Leipzig, Bitterfeld, Weimar, +Heilbronn, and Stuttgart, descending near Goppingen; the time +occupied in the flight was upwards of 38 hours. + +In landing, the airship collided with a pear-tree, which damaged +the bows and tore open two sections of the envelope, but repairs +on the spot enabled the return journey to Friedrichshafen to be +begun 24 hours later. In spite of the mishap the Zeppelin had +once more proved itself as a possible engine of war, and +thenceforth Germany pinned its faith to the dirigible, only +developing the aeroplane to such an extent as to keep abreast of +other nations. By the outbreak of war, nearly 30 Zeppelins had +been constructed; considerably more than half of these were +destroyed in various ways, but the experiments carried on with +each example of the type permitted of improvements being made. +The first fatality occurred in September, 1913, when the +fourteenth Zeppelin to be constructed, known as Naval Zeppelin +L.1, was wrecked in the North Sea by a sudden storm and her +crew of thirteen were drowned. About three weeks after this, +Naval Zeppelin L.2, the eighteenth in order of building, +exploded in mid-air while manoeuvring over Johannisthal. She +was carrying a crew of 25, who were all killed. + +By 1912 the success of the Zeppelin type brought imitators. +Chief among them was the Schutte-Lanz, a Mannheim firm, which +produced a rigid dirigible with a wooden framework, wire braced. +This was not a cylinder like the Zeppelin, but reverted to the +cigar shape and contained about the same amount of gas as the +Zeppelin type. The Schutte-Lanz was made with two gondolas +rigidly attached to the envelope in which the gas bags were +placed. The method of construction involved greater weight than +was the case with the Zeppelin, but the second of these vessels, +built with three gondolas containing engines, and a navigating +cabin built into the hull of the airship itself, proved quite +successful as a naval scout until wrecked on the islands off the +coast of Denmark late in 1914. The last Schutte-Lanz to be +constructed was used by the Germans for raiding England, and was +eventually brought down in flames at Cowley. + + + +V. BRITISH AIRSHIP DESIGN + +As was the case with the aeroplane, Great Britain left France +and Germany to make the running in the early days of airship +construction; the balloon section of the Royal Engineers was +compelled to confine its energies to work with balloons pure and +simple until well after the twentieth century had dawned, and +such experiments as were made in England were done by private +initiative. As far back as 1900 Doctor Barton built an airship +at the Alexandra Palace and voyaged across London in it. Four +years later Mr E. T. Willows of Cardiff produced the first +successful British dirigible, a semi-rigid 74 feet in length and +18 feet in diameter, engined with a 7 horse-power Peugot +twin-cylindered motor. This drove a two-bladed propeller at the +stern for propulsion, and also actuated a pair of auxiliary +propellers at the front which could be varied in their direction +so as to control the right and left movements of the airship. +This device was patented and the patent was taken over by the +British Government, which by 1908 found Mr Willow's work of +sufficient interest to regard it as furnishing data for +experiment at the balloon factory at Farnborough. In 1909, +Willows steered one of his dirigibles to London from Cardiff in +a little less than ten hours, making an average speed of over 14 +miles an hour. The best speed accomplished was probably +considerably greater than this, for at intervals of a few miles, +Willows descended near the earth to ascertain his whereabouts +with the help of a megaphone. It must be added that he carried +a compass in addition to his megaphone. He set out for Paris in +November of 1910, reached the French coast, and landed near +Douai. Some damage was sustained in this landing, but, after +repair, the trip to Paris was completed. + +Meanwhile the Government balloon factory at Farnborough began +airship construction in 1907; Colonel Capper, R.E., and S. F. +Cody were jointly concerned in the production of a semi-rigid. +Fifteen thicknesses of goldbeaters' skin--about the most +expensive covering obtainable--were used for the envelope, which +was 25 feet in diameter. A slight shower of rain in which the +airship was caught led to its wreckage, owing to the absorbent +quality of the goldbeaters' skin, whereupon Capper and Cody set +to work to reproduce the airship and its defects on a larger +scale. The first had been named 'Nulli Secundus' and the second +was named 'Nulli Secundus II.' Punch very appropriately +suggested that the first vessel ought to have been named 'Nulli +Primus,' while a possible third should be christened 'Nulli +Tertius.' 'Nulli Secundus II.' was fitted with a 100 horse-power +engine and had an envelope of 42 feet in diameter, the +goldbeaters' skin being covered in fabric and the car being +suspended by four bands which encircled the balloon envelope. +In October of 1907, 'Nulli Secundus II.' made a trial flight +from Farnborough to London and was anchored at the Crystal +Palace. The wind sprung up and took the vessel away from its +mooring ropes, wrecking it after the one flight. + +Stagnation followed until early in 1909, when a small airship +fitted with two 12 horse-power motors and named the 'Baby' was +turned out from the balloon factory. This was almost +egg-shaped, the blunt end being forward, and three inflated fins +being placed at the tail as control members. A long car with +rudder and elevator at its rear-end carried the engines and +crew; the 'Baby' made some fairly successful flights and gave a +good deal of useful data for the construction of later vessels. + +Next to this was 'Army Airship 2A 'launched early in 1910 and +larger, longer, and narrower in design than the Baby. The +engine was an 80 horse-power Green motor which drove two pairs +of propellers; small inflated control members were fitted at the +stern end of the envelope, which was 154 feet in length. The +suspended car was 84 feet long, carrying both engines and crew, +and the Willows idea of swivelling propellers for governing the +direction was used in this vessel. In June of that year a new, +small-type dirigible, the 'Beta,' was produced, driven by a 30 +horse-power Green engine with which she flew over 3,000 miles. +She was the most successful British dirigible constructed up to +that time, and her successor, the 'Gamma,' was built on similar +lines. The 'Gamma' was a larger vessel, however, produced in +1912, with flat, controlling fins and rudder at the rear end of +the envelope, and with the conventional long car suspended at +some distance beneath the gas bag. By this time, the mooring +mast, carrying a cap of which the concave side fitted over the +convex nose of the airship, had been originated. The cap was +swivelled, and, when attached to it, an airship was held nose on +to the wind, thus reducing by more than half the dangers +attendant on mooring dirigibles in the open. + +Private subscription under the auspices of the Morning Post got +together sufficient funds in 1910 for the purchase of a Lebaudy +airship, which was built in France, flown across the Channel, and +presented to the Army Airship Fleet. This dirigible was 337 feet +long, and was driven by two 135 horse-power Panhard motors, each +of which actuated two propellers. The journey from Moisson to +Aldershot was completed at a speed of 36 miles an hour, but the +airship was damaged while being towed into its shed. On May of +the following year, the Lebaudy was brought out for a flight, +but, in landing, the guide rope fouled in trees and sheds and +brought the airship broadside on to the wind; she was driven into +some trees and wrecked to such an exteent that rebuilding was +considered an impossibility. A Clement Bayard, bought by the +army airship section, became scrap after even less flying than +had been accomplished by the Lebaudy. + +In April of 1910,, the Admiralty determined on a naval air +service, and set about the production of rigid airships which +should be able to compete with Zeppelins as naval scouts. The +construction was entrusted to Vickers, Ltd., who set about the +task at their Barrow works and built something which, when tested +after a year's work, was found incapable of lifting its own +weight. This defect was remedied by a series of alterations, and +meanwhile the unofficial title of 'Mayfly' was given to the +vessel. + +Taken over by the Admiralty before she had passed any flying +tests, the 'Mayfly' was brought out on September 24th, 1911, for +a trial trip, being towed out from her shed by a tug. When ha]f +out from the shed, the envelope was caught by a light +cross-wind, and, in spite of the pull from the tug, the great +fabric broke in half, nearly drowning the crew, who had to dive +in order to get clear of the wreckage. + +There was considerable similarity in form, though not in +performance, between the Mayfly and the prewar Zeppelin. The +former was 510 feet in length, cylindrical in form, with a +diameter of 48 feet, and divided into 19 gas-bag compartments. +The motive power consisted of two 200 horse-power Wolseley +engines. After its failure, the Naval Air Service bought an +Astra-Torres airship from France and a Parseval from Germany, +both of which proved very useful in the early days of the War, +doing patrol work over the Channel before the Blimps came into +being. + +Early in 1915 the 'Blimp' or 'S.S.' type of coastal airship +was evolved in response to the demand for a vessel which could +be turned out quickly and in quantities. There was urgent +demand, voiced by Lord Fisher, for a type of vessel capable of +maintaining anti-submarine patrol off the British coasts, and +the first S.S. airships were made by combining a gasbag with +the most available type of aeroplane fuselage and engine, and +fitting steering gear. The 'Blimp' consisted of a B.E. fuselage +with engine and geared-down propeller, and seating for pilot and +observer, attached to an envelope about 150 feet in length. +With a speed of between 35 and 40 miles an hour, the 'Blimp' had +a cruising capacity of about ten hours; it was fitted with +wireless set, camera, machine-gun, and bombs, and for submarine +spotting and patrol work generally it proved invaluable, though +owing to low engine power and comparatively small size, its uses +were restricted to reasonably fair weather. For work farther out +at sea and in all weathers, airships known as the coast patrol +type, and more commonly as 'coastals,' were built, and later the +'N.S.' or North Sea type, still larger and more weather-worthy, +followed. By the time the last year of the War came, Britain +led the world in the design of non-rigid and semi-rigid +dirigibles. The 'S.S.' or 'Blimp' had been improved to a speed +of 50 miles an hour, carrying a crew of three, and the endurance +record for the type was 18 1/2 hours, while one of them had +reached a height of 10,000 feet. The North Sea type of +non-rigid was capable of travelling over 20 hours at full speed, +or forty hours at cruising speed, and the number of non-rigids +belonging to the British Navy exceeded that of any other +country. + +It was owing to the incapacity--apparent or real-- of the +British military or naval designers to produce a satisfactory +rigid airship that the 'N.S.' airship was evolved. The first of +this type was produced in 1916, and on her trials she was voted +an unqualified success, in consequence of which the building of +several more was pushed on. The envelope, of 360,000 cubic feet +capacity, was made on the Astra-Torres principle of three lobes, +giving a trefoil section. The ship carried four fins, to three +of which the elevator and rudder flaps were attached; petrol +tanks were placed inside the envelope, under which was rigged a +long covered-in car, built up of a light steel tubular framework +35 feet in length. The forward portion was covered with +duralumin sheeting, an aluminium alloy which, unlike aluminium +itself, is not affected by the action of sea air and water, and +the remainder with fabric laced to the framework. Windows and +port-holes were provided to give light to the crew, and the +controls and navigating instruments were placed forward, with the +sleeping accommodation aft. The engines were mounted in a power +unit structure, separate from the car and connected by wooden +gang ways supported by wire cables. A complete electrical +installation of two dynamos and batteries for lights, signalling +lamps, wireless, telephones, etc., was carried, and the motive +power consisted of either two 250 horse-power Rolls-Royce engines +or two 240 horse-power Fiat engines. The principal dimensions of +this type are length 262 feet, horizontal diameter 56 feet 9 +inches, vertical diameter 69 feet 3 inches. The gross lift is +24,300 lbs. and the disposable lift without crew, petrol, oil, +and ballast 8,500 lbs. The normal crew carried for patrol work +was ten officers and men. This type holds the record of 101 +hours continuous flight on patrol duty. + +In the matter of rigid design it was not until 1913 that the +British Admiralty got over the fact that the 'Mayfly' would not, +and decided on a further attempt at the construction of a rigid +dirigible. The contract for this was signed in March of 1914; +work was suspended in the following February and begun again in +July, 1915, but it was not until January of 1917 that the +ship was finished, while her trials were not completed until +March of 1917, when she was taken over by the Admiralty. The +details of the construction and trial of this vessel, known as +'No. 9,' go to show that she did not quite fill the contract +requirements in respect of disposable lift until a number of +alterations had been made. The contract specified that a speed +of at least 45 miles per hour was to be attained at full engine +power, while a minimum disposable lift of 5 tons was to be +available for movable weights, and the airship was to be capable +of rising to a height of 2,000 feet. Driven by four Wolseley +Maybach engines of 180 horse-power each, the lift of the vessel +was not sufficient, so it was decided to remove the two engines +in the after car and replace them by a single engine of 250 +horsepower. With this the vessel reached the contract speed of +45 miles per hour with a cruising radius of 18 hours, equivalent +to 800 miles when the engines were running at full speed. The +vessel served admirably as a training airship, for, by the time +she was completed, the No. 23 class of rigid airship had come to +being, and thus No. 9 was already out of date. + +Three of the 23 class were completed by the end of 1917; it was +stipulated that they should be built with a speed of at least 55 +miles per hour, a minimum disposable lift of 8 tons, and a +capability of rising at an average rate of not less than 1,000 +feet per minute to a height of 3,000 feet. The motive power +consisted of four 250 horse-power Rolls-Royce engines, one in +each of the forward and after cars and two in a centre car. +Four-bladed propellers were used throughout the ship. + +A 23X type followed on the 23 class, but by the time two ships +had been completed, this was practically obsolete. The No. 31 +class followed the 23X; it was built on Schutte-Lanz lines, 615 +feet in length, 66 feet diameter, and a million and a half cubic +feet capacity. The hull was similar to the later types of +Zeppelin in shape, with a tapering stern and a bluff, rounded +bow. Five cars each carrying a 250 horse-power Rolls-Royce +engine, driving a single fixed propeller, were fitted, and on +her trials R.31 performed well, especially in the matter of +speed. But the experiment of constructing in wood in the +Schutte-Lanz way adopted with this vessel resulted in failure +eventually, and the type was abandoned. + +Meanwhile, Germany had been pushing forward Zeppelin design and +straining every nerve in the improvement of rigid dirigible +construction, until L.33 was evolved; she was generally known as +a super-Zeppelin, and on September 24th, 1916, six weeks +after her launching, she was damaged by gun-fire in a raid over +London, being eventually compelled to come to earth at Little +Wigborough in Essex. The crew gave themselves up after having +set fire to the ship, and though the fabric was totally +destroyed, the structure of the hull remained intact, so that +just as Germany was able to evolve the Gotha bomber from the +HandleyPage delivered at Lille, British naval constructors were +able to evolve the R.33 type of airship from the Zeppelin +framework delivered at Little Wigborough. Two vessels, R.33 and +R.34, were laid down for completion; three others were also put +down for construction, but, while R.33 and R.34 were built +almost entirely from the data gathered from the wrecked L.33, +the three later vessels embody more modern design, including a +number of improvements, and more especially greater disposable +lift. It has been commented that while the British authorities +were building R.33 and R.34, Germany constructed 30 Zeppelins on +4 slips, for which reason it may be reckoned a matter for +congratulation that the rigid airship did not decide the fate of +the War. The following particulars of construction of the R.33 +and R.34 types are as given by Major Whale in his survey of +British Airships:-- + +'In all its main features the hull structure of R.33 and R.34 +follows the design of the wrecked German Zeppelin airship L.33. +'The hull follows more nearly a true stream-line shape than in +the previous ships constructed of duralumin, in which a greater +proportion of the greater length was parallel-sided. The +Germans adopted this new shape from the Schutte-Lanz design and +have not departed from this practice. This consists of a short, +parallel body with a long, rounded bow and a long tapering stem +culminating in a point. The overall length of the ship is 643 +feet with a diameter of 79 feet and an extreme height of 92 +feet. + +'The type of girders in this class has been much altered from +those in previous ships. The hull is fitted with an internal +triangular keel throughout practically the entire length. This +forms the main corridor of the ship, and is fitted with a +footway down the centre for its entire length. It contains water +ballast and petrol tanks, bomb storage and crew accommodation, +and the various control wires, petrol pipes, and electric leads +are carried along the lower part. + +'Throughout this internal corridor runs a bridge girder, from +which the petrol and water ballast tanks are supported. These +tanks are so arranged that they can be dropped clear of the +ship. Amidships is the cabin space with sufficient room for a +crew of twenty-five. Hammocks can be swung from the bridge +girder before mentioned. + +'In accordance with the latest Zeppelin practice, monoplane +rudders and elevators are fitted to the horizontal and vertical +fins. + +'The ship is supported in the air by nineteen gas bags, which +give a total capacity of approximately two million cubic feet of +gas. The gross lift works out at approximately 59 1/2 tons, of +which the total fixed weight is 33 tons, giving a disposable +lift of 26 1/2 tons. + +'The arrangement of cars is as follows: At the forward end the +control car is slung, which contains all navigating instruments +and the various controls. Adjoining this is the wireless cabin, +which is also fitted for wireless telephony. Immediately aft of +this is the forward power car containing one engine, which gives +the appearance that the whole is one large car. + +'Amidships are two wing cars, each containing a single engine. +These are small and just accommodate the engines with sufficient +room for mechanics to attend to them. Further aft is another +larger car which contains an auxiliary control position and two +engines. + +'It will thus be seen that five engines are installed in the +ship; these are all of the same type and horsepower, namely, 250 +horse-power Sunbeam. R.33 was constructed by Messrs Armstrong, +Whitworth, Ltd.; while her sister ship R.34 was built by Messrs +Beardmore on the Clyde.' + +Of the two vessels, R.34 appeared rather more airworthy than her +sister ship; the lift of the ship justified the carrying of a +greater quantity of fuel than had been provided for, and, as she +was considered suitable for making a Transatlantic crossing, +extra petrol tanks were fitted in the hull and a new type of +outer cover was fitted with a view to her making the Atlantic +crossing. She made a 21-hour cruise over the North of England +and the South of Scotland at the end of May, 1919, and +subsequently went for a longer cruise over Denmark, the Baltic, +and the north coast of Germany, remaining in the air for 56 hours +in spite of very bad weather conditions. Finally, July 2nd was +selected as the starting date for the cross Atlantic flight; the +vessel was commanded by Major G. H. Scott, A.F.C., with Captain +G. S. Greenland as first officer, Second-Lieut. H. F. Luck as +second officer, and Lieut. J. D. Shotter as engineer officer. +There were also on board Brig.-Gen. E. P. Maitland, representing +the Air Ministry, Major J. E. M. Pritchard, representing the +Admiralty, and Lieut.-Col. W. H. Hemsley of the Army Aviation +Department. In addition to eight tons of petrol, R.34 carried a +total number of 30 persons from East Fortune to Long Island, N.Y. + +There being no shed in America capable of accommodating the +airship, she had to be moored in the open for refilling with fuel +and gas, and to make the return journey almost immediately. + +Brig.-Gen. Maitland's account of the flight, in itself a record +as interesting as valuable, divides the outward journey into two +main stages, the first from East Fortune to Trinity Bay, +Newfoundland, a distance of 2,050 sea miles, and the second and +more difficult stage to Mineola Field, Long Island, 1,080 sea +miles. An easy journey was experienced until Newfoundland was +reached, but then storms and electrical disturbances rendered it +necessary to alter the course, in consequence of which petrol +began to run short. Head winds rendered the shortage still more +acute, and on Saturday, July 5th, a wireless signal was sent out +asking for destroyers to stand by to tow. However, after an +anxious night, R.33 landed safely at Mineola Field at 9.55 a.m. +on July 6th, having accomplished the journey in 108 hours 12 +minutes. + +She remained at Mineola until midnight of July 9th, when, +although it had been intended that a start should be made by +daylight for the benefit of New York spectators, an approaching +storm caused preparations to be advanced for immediate +departure. She set out at 5.57 a.m. by British summer time, +and flew over New York in the full glare of hundreds of +searchlights before heading out over the Atlantic. A following +wind assisted the return voyage, and on July 13th, at 7.57 a.m., +R.34 anchored at Pulham, Norfolk, having made the return journey +in 75 hours 3 minutes, and proved the suitability of the +dirigible for Transatlantic commercial work. R.80, launched on +July 19th, 1920, afforded further proof, if this were needed. + +It is to be noted that nearly all the disasters to airships have +been caused by launching and landing-- the type is safe enough +in the air, under its own power, but its bulk renders it +unwieldy for ground handling. The German system of handling +Zeppelins in and out of their sheds is, so far, the best +devised: this consists of heavy trucks running on rails through +the sheds and out at either end; on descending, the trucks are +run out, and the airship is securely attached to them outside +the shed; the trucks are then run back into the shed, taking the +airship with them, and preventing any possibility of the wind +driving the envelope against the side of the shed before it is +safely housed; the reverse process is adopted in launching, +which is thus rendered as simple as it is safe. + + + +VI. THE AIRSHIP COMMERCIALLY + +Prior to the war period, between the years 1910 and 1914, a +German undertaking called the Deutsche Luftfahrt Actien +Gesellschaft conducted a commercial Zeppelin service in which +four airships known as the Sachsan, Hansa, Victoria Louise, and +Schwaben were used. During the four years of its work, the +company carried over 17,000 passengers, and over 100,000 miles +were flown without incurring one fatality and with only minor +and unavoidable accidents to the vessels composing the service. +Although a number of English notabilities made voyages in these +airships, the success of this only experiment in commercial +aerostation seems to have been forgotten since the war. There +was beyond doubt a military aim in this apparently peaceful use +of Zeppelin airships; it is past question now that all Germany's +mechanical development in respect of land sea, and air transport +in the years immediately preceding the war, was accomplished +with the ulterior aim of military conquest, but, at the same +time, the running of this service afforded proof of the +possibility of establishing a dirigible service for peaceful +ends, and afforded proof too, of the value of the dirigible as a +vessel of purely commercial utility. + +In considering the possibility of a commercial dirigible +service, it is necessary always to bear in mind the +disadvantages of first cost and upkeep as compared with the +aeroplane. The building of a modern rigid is an exceedingly +costly undertaking, and the provision of an efficient supply of +hydrogen gas to keep its compartments filled is a very large +item in upkeep of which the heavier-than-air machine goes free. +Yet the future of commercial aeronautics so far would seem to +lie with the dirigible where very long voyages are in question. +No matter how the aeroplane may be improved, the possibility of +engine failure always remains as a danger for work over water. +In seaplane or flying boat form, the danger is still present in +a rough sea, though in the American Transatlantic flight, N.C.3, +taxi-ing 300 miles to the Azores after having fallen to the +water, proved that this danger is not so acute as is generally +assumed. Yet the multiple-engined rigid, as R.34 showed on her +return voyage, may have part of her power plant put out of +action altogether and still complete her voyage very +successfully, which, in the case of mail carrying and services +run strictly to time, gives her an enormous advantage over the +heavier-than-air machine. + +'For commercial purposes,' General Sykes has remarked, 'the +airship is eminently adapted for long distance journeys +involving non-stop flights. It has this inherent advantage over +the aeroplane, that while there appears to be a limit to the +range of the aeroplane as at present constructed, there is +practically no limit whatever to that of the airship, as this +can be overcome by merely increasing the size. It thus appears +that for such journeys as crossing the Atlantic, or crossing the +Pacific from the west coast of America to Australia or Japan, +the airship will be peculiarly suitable. It having been +conceded that the scope of the airship is long distance travel, +the only type which need be considered for this purpose is the +rigid. The rigid airship is still in an embryonic state, but +sufficient has already been accomplished in this country, and +more particularly in Germany, to show that with increased +capacity there is no reason why, within a few years' time, +airships should not be built capable of completing the circuit +of the globe and of conveying sufficient passengers and +merchandise to render such an undertaking a paying proposition.' + +The British R.38 class, embodying the latest improvements in +airship design outside Germany, gives a gross lift per airship +of 85 tons and a net lift of about 45 tons. The capacity of +the gas bags is about two and three-quarter million cubic feet, +and, travelling at the rate of 45 miles per hour, the cruising +range of the vessel is estimated at 8.8 days. Six engines, each +of 350 horse-power, admit of an extreme speed of 70 miles per +hour if necessary. + +The last word in German design is exemplified in the rigids L.70 +and L.71, together with the commercial airship 'Bodensee.' +Previous to the construction of these, the L.65 type is +noteworthy as being the first Zeppelin in which direct drive of +the propeller was introduced, together with an improved and +lighter type of car. L.70 built in 1918 and destroyed by the +British naval forces, had a speed of about 75 miles per hour; +L.71 had a maximum speed of 72 miles per hour, a gas bag +capacity of 2,420,000 cubic feet, and a length of 743 feet, +while the total lift was 73 tons. Progress in design is best +shown by the progress in useful load; in the L.70 and L.71 +class, this has been increased to 58.3 per cent, while in the +Bodensee it was ever higher. + +As was shown in R.34's American flight, the main problem in +connection with the commercial use of dirigibles is that of +mooring in the open. The nearest to a solution of this problem, +so far, consists in the mast carrying a swivelling cap; this has +been tried in the British service with a non-rigid airship, +which was attached to a mast in open country in a gale of 52 +miles an hour without the slightest damage to the airship. In +its commercial form, the mast would probably take the form of a +tower, at the top of which the cap would revolve so that the +airship should always face the wind, the tower being used for +embarkation and disembarkation of passengers and the provision +of fuel and gas. Such a system would render sheds unnecessary +except in case of repairs, and would enormously decrease the +establishment charges of any commercial airship. + +All this, however, is hypothetical. Remains the airship of +to-day, developed far beyond the promise of five years ago, +capable, as has been proved by its achievements both in Britain +and in Germany, of undertaking practically any given voyage with +success. + + + +VII. KITE BALLOONS + +As far back as the period of the Napoleonic wars, the balloon +was given a place in warfare, but up to the Franco-Prussian +Prussian War of 1870-71 its use was intermittent. The Federal +forces made use of balloons to a small extent in the American +Civil War; they came to great prominence in the siege of Paris, +carrying out upwards of three million letters and sundry carrier +pigeons which took back messages into the besieged city. +Meanwhile, as captive balloons, the German and other armies used +them for observation and the direction of artillery fire. In +this work the ordinary spherical balloon was at a grave +disadvantage; if a gust of wind struck it, the balloon was blown +downward and down wind, generally twirling in the air and +upsetting any calculations and estimates that might be made by +the observers, while in a wind of 25 miles an hour it could not +rise at all. The rotatory movement caused by wind was stopped +by an experimenter in the Russo-Japanese war, who fixed to the +captive observation balloons a fin which acted as a rudder. This +did not stop the balloon from being blown downward and away from +its mooring station, but this tendency was overcome by a +modification designed in Germany by the Parseval-Siegsfield +Company, which originated what has since become familiar as the +'Sausage' or kite balloon. This is so arranged that the forward +end is tilted up into the wind, and the underside of the gas +bag, acting as a plane, gives the balloon a lifting tendency in +a wind, thus counteracting the tendency of the wind to blow it +downward and away from its mooring station. Smaller bags are +fitted at the lower and rear end of the balloon with openings +that face into the wind; these are thus kept inflated, and they +serve the purpose of a rudder, keeping the kite balloon steady +in the air. + +Various types of kite balloon have been introduced; the original +German Parseval-Siegsfield had a single air bag at the stern +end, which was modified to two, three, or more lobes in later +varieties, while an American experimental design attempted to do +away with the attached lobes altogether by stringing out a +series of small air bags, kite fashion, in rear of the main +envelope. At the beginning of the War, Germany alone had kite +balloons, for the authorities of the Allied armies con-sidered +that the bulk of such a vessel rendered it too conspicuous a +mark to permit of its being serviceable. The Belgian arm alone +possessed two which, on being put into service, were found +extremely useful. The French followed by constructing kite +balloons at Chalais Meudon, and then, after some months of +hostilities and with the example of the Royal Naval Air Service +to encourage them, the British military authorities finally took +up the construction and use of kite balloons for +artillery-spotting and general observation purposes. Although +many were brought down by gun-fire, their uses far outweighed +their disadvantages, and toward the end of the War, hardly a +mile of front was without its 'Sausage.' + +For naval work, kite balloons were carried in a specially +constructed hold in the forepart of certain vessels; when +required for use, the covering of the hold was removed, the +kite balloon inflated and released to the required height by +means of winches as in the case of the land work. The +perfecting of the 'Coastal' and N.S. types of airship, together +with the extension of wireless telephony between airship and +cruiser or other warship, in all probability will render the use +of the kite balloon unnecessary in connection with naval +scouting. But, during the War, neither wireless telephony nor +naval airships had developed sufficiently to render the Navy +independent of any means that might come to hand, and the +fitting of kite balloons in this fashion filled a need of the +times. + +A necessary accessory of the kite balloon is the parachute, +which has a long history. Da Vinci and Veranzio appear to have +been the first exponents, the first in the theory and the latter +in the practice of parachuting. Montgolfier experimented at +Annonay before he constructed his first hot air-balloon, and in +1783 a certain Lenormand dropped from a tree in a parachute. +Blanchard the balloonist made a spectacle of parachuting, and +made it a financial success; Cocking, in 1836, attempted to use +an inverted form of parachute; taken up to a height of 3,000 +feet, he was cut adrift, when the framework of the parachute +collapsed and Cocking was killed. + +The rate of fall is slow in parachuting to the ground. Frau +Poitevin, making a descent from a height of 6,000 feet, took 45 +minutes to reach the ground, and, when she alighted, her +husband, who had taken her up, had nearly got his balloon packed +up. Robertson, another parachutist is said to have descended +from a height of 10,000 feet in 35 minutes, or at a rate of +nearly 5 feet per second. During the War Brigadier-General +Maitland made a parachute descent from a height of 10,000 feet, +the time taken being about 20 minutes. + +The parachute was developed considerably during the War period, +the main requirement, that of certainty in opening, being +considerably developed. Considered a necessary accessory for +kite balloons, the parachute was also partially adopted for use +with aeroplanes in the later War period, when it was contended +that if a machine were shot down in flames, its occupants would +be given a far better chance of escape if they had parachutes. +Various trials were made to demonstrate the extreme efficiency +of the parachute in modern form, one of them being a descent +from the upper ways of the Tower Bridge to the waters of the +Thames, in which short distance the 'Guardian Angel' type of +parachute opened and cushioned the descent for its user. + +For dirigibles, balloons, and kite balloons the parachute is +an essential. It would seem to be equally essential in the case +of heavier-than-air machines, but this point is still debated. +Certainly it affords the occupant of a falling aeroplane a +chance, no matter how slender, of reaching the ground in safety, +and, for that reason, it would seem to have a place in aviation +as well as in aerostation. + + + +PART IV. ENGINE DEVELOPMENT + +I. THE VERTICAL TYPE + +The balloon was but a year old when the brothers Robert, in 1784 +attempted propulsion of an aerial vehicle by hand-power, +and succeeded, to a certain extent, since they were able to make +progress when there was only a slight wind to counteract their +work. But, as may be easily understood, the manual power +provided gave but a very slow speed, and in any wind it all the +would-be airship became an uncontrolled balloon. + +Henson and Stringfellow, with their light steam engines, were +first to attempt conquest of the problem of mechanical +propulsion in the air; their work in this direction is so fully +linked up with their constructed models that it has been +outlined in the section dealing with the development of the +aeroplane. But, very shortly after these two began, there came +into the field a Monsieur Henri Giffard, who first achieved +success in the propulsion by mechanical means of dirigible +balloons, for his was the first airship to fly against the wind. +He employed a small steam-engine developing about 3 horse-power +and weighing 350 lbs. with boiler, fitting the whole in a car +suspended from the gas-bag of his dirigible. The propeller which +this engine worked was 11 feet in diameter, and the inventor, who +made several flights, obtained a speed of 6 miles an hour against +a slight wind. The power was not sufficient to render the +invention practicable, as the dirigible could only be used in +calm weather, but Giffard was sufficiently encouraged by his +results to get out plans for immense dirigibles, which through +lack of funds he was unable to construct. When, later, his +invention of the steam-injector gave him the means he desired, he +became blind, and in 1882 died, having built but the one famous +dirigible. + +This appears to have been the only instance of a steam engine +being fitted to a dirigible; the inherent disadvantage of this +form of motive power is that a boiler to generate the steam must +be carried, and this, together with the weight of water and +fuel, renders the steam engine uneconomical in relation to the +lift either of plane or gas-bag. Again, even if the weight +could be brought down to a reasonable amount, the attention +required by steam plant renders it undesirable as a motive power +for aircraft when compared with the internal combustion engine. + +Maxim, in Artificial and Natural Flight, details the engine +which he constructed for use with his giant experimental flying +machine, and his description is worthy of reproduction since it +is that of the only steam engine besides Giffard's, and apart +from those used for the propulsion of models, designed for +driving an aeroplane. 'In 1889,' Maxim says, 'I had my +attention drawn to some very thin, strong, and comparatively +cheap tubes which were being made in France, and it was only +after I had seen these tubes that I seriously considered the +question of making a flying machine. I obtained a large +quantity of them and found that they were very light, that they +would stand enormously high pressures, and generate a very large +quantity of steam. Upon going into a mathematical calculation of +the whole subject, I found that it would be possible to make a +machine on the aeroplane system, driven by a steam engine, which +would be sufficiently strong to lift itself into the air. I +first made drawings of a steam engine, and a pair of these +engines was afterwards made. These engines are constructed, for +the most part, of a very high grade of cast steel, the cylinders +being only 3/32 of an inch thick, the crank shafts hollow, and +every part as strong and light as possible. They are compound, +each having a high-pressure piston with an area of 20 square +inches, a low-pressure piston of 50.26 square inches, and a +common stroke of 1 foot. When first finished they were found to +weigh 300 lbs. each; but after putting on the oil cups, felting, +painting, and making some slight alterations, the weight was +brought up to 320 lbs. each, or a total of 640 lbs. for the +two engines, which have since developed 362 horsepower with a +steam pressure of 320 lbs. per square inch.' + +The result is remarkable, being less than 2 lbs. weight per +horse-power, especially when one considers the state of +development to which the steam engine had attained at the time +these experiments were made. The fining down of the internal +combustion engine, which has done so much to solve the problems +of power in relation to weight for use with aircraft, had not +then been begun, and Maxim had nothing to guide him, so far as +work on the part of his predecessors was concerned, save the +experimental engines of Stringfellow, which, being constructed +on so small a scale in comparison with his own, afforded little +guidance. Concerning the factor of power, he says: 'When first +designing this engine, I did not know how much power I might +require from it. I thought that in some cases it might be +necessary to allow the high-pressure steam to enter the +low-pressure cylinder direct, but as this would involve a +considerable loss, I constructed a species of injector. This +injector may be so adjusted (hat when the steam in the boiler +rises above a certain predetermined point, say 300 lbs., to the +square inch, it opens a valve and escapes past the high-pressure +cylinder instead of blowing off at the safety valve. In +escaping through this valve, a fall of about 200 lbs. pressure +per square inch is made to do work on the surrounding steam and +drive it forward in the pipe, producing a pressure on the +low-pressure piston considerably higher than the back-pressure +on the high-pressure piston. In this way a portion of the work +which would otherwise be lost is utilised, and it is possible, +with an unlimited supply of steam, to cause the engines to +develop an enormous amount of power.' + +With regard to boilers, Maxim writes, + +'The first boiler which I made was constructed something on the +Herreshof principle, but instead of having one simple pipe in +one very long coil, I used a series of very small and light +pipes, connected in such a manner that there was a rapid +circulation through the whole--the tubes increasing in size and +number as the steam was generated. I intended that there should +be a pressure of about 100 lbs. more on the feed water end of +the series than on the steam end, and I believed that this +difference in pressure would be sufficient to ensure direct and +positive circulation through every tube in the series. The first +boiler was exceedingly light, but the workmanship, as far as +putting the tubes together was concerned, was very bad, and it +was found impossible to so adjust the supply of water as to make +dry steam without overheating and destroying the tubes. + +'Before making another boiler I obtained a quantity of copper +tubes, about 8 feet long, 3/8 inch external diameter, and 1/50 of +an inch thick. I subjected about 100 of these tubes to an +internal pressure of 1 ton per square inch of cold kerosene oil, +and as none of them leaked I did not test any more, but +commenced my experiments by placing some of them in a white-hot +petroleum fire. I found that I could evaporate as much as 26 +1/2 lbs. of water per square foot of heating surface per hour, +and that with a forced circulation, although the quantity of +water passing was very small but positive, there was no danger +of overheating. I conducted many experiments with a pressure of +over 400 lbs. per square inch, but none of the tubes failed. +I then mounted a single tube in a white-hot furnace, also with a +water circulation, and found that it only burst under steam at a +pressure of 1,650 lbs. per square inch. A large boiler, +having about 800 square feet of heating surface, including the +feed-water heater, was then constructed. This boiler is about 4 +1/2 feet wide at the bottom, 8 feet long and 6 feet high. It +weighs, with the casing, the dome, and the smoke stack and +connections, a little less than 1,000 lbs. The water first +passes through a system of small tubes--1/4 inch in diameter and +1/60 inch thick--which were placed at the top of the boiler and +immediately over the large tubes.... This feed-water heater is +found to be very effective. It utilises the heat of the +products of combustion after they have passed through the boiler +proper and greatly reduces their temperature, while the +feed-water enters the boiler at a temperature of about 250 F. A +forced circulation is maintained in the boiler, the feed-water +entering through a spring valve, the spring valve being adjusted +in such a manner that the pressure on the water is always 30 +lbs. per square inch in excess of the boiler pressure. This +fall of 30 lbs. in pressure acts upon the surrounding hot water +which has already passed through the tubes, and drives it down +through a vertical outside tube, thus ensuring a positive and +rapid circulation through all the tubes. This apparatus is +found to act extremely well.' + +Thus Maxim, who with this engine as power for his large +aeroplane achieved free flight once, as a matter of experiment, +though for what distance or time the machine was actually off +the ground is matter for debate, since it only got free by +tearing up the rails which were to have held it down in the +experiment. Here, however, was a steam engine which was +practicable for use in the air, obviously, and only the rapid +success of the internal combustion engine prevented the +steam-producing type from being developed toward perfection. + +The first designers of internal combustion engines, knowing +nothing of the petrol of these days, constructed their examples +with a view to using gas as fuel. As far back as 1872 Herr Paul +Haenlein obtained a speed of about 10 miles an hour with a +balloon propelled by an internal combustion engine, of which the +fuel was gas obtained from the balloon itself. The engine in +this case was of the Lenoir type, developing some 6 horse-power, +and, obviously, Haenlein's flights were purely experimental and +of short duration, since he used the gas that sustained him and +decreased the lifting power of his balloon with every stroke of +the piston of his engine. No further progress appears to have +been made with the gas-consuming type of internal combustion +engine for work with aircraft; this type has the disadvantage of +requiring either a gas-producer or a large storage capacity for +the gas, either of which makes the total weight of the power +plant much greater than that of a petrol engine. The latter type +also requires less attention when working, and the fuel is more +convenient both for carrying and in the matter of carburation. + +The first airship propelled by the present-day type of internal +combustion engine was constructed by Baumgarten and Wolfert in +1879 at Leipzig, the engine being made by Daimler with a view to +working on benzine--petrol as a fuel had not then come to its +own. The construction of this engine is interesting since it was +one of the first of Daimler's make, and it was the development +brought about by the experimental series of which this engine +was one that led to the success of the motor-car in very few +years, incidentally leading to that fining down of the internal +combustion engine which has facilitated the development of the +aeroplane with such remarkable rapidity. Owing to the faulty +construction of the airship no useful information was obtained +from Daimler's pioneer installation, as the vessel got out of +control immediately after it was first launched for flight, and +was wrecked. Subsequent attempts at mechanically-propelled +flight by Wolfert ended, in 1897, in the balloon being set on +fire by an explosion of benzine vapour, resulting in the death +of both the aeronauts. + +Daimler, from 1882 onward, devoted his attention to the +perfecting of the small, high-speed petrol engine for motor-car +work, and owing to his efforts, together with those of other +pioneer engine-builders, the motorcar was made a success. In a +few years the weight of this type of engine was reduced from near +on a hundred pounds per horse-power to less than a tenth of that +weight, but considerable further improvement had to be made +before an engine suitable for use with aircraft was evolved. + +The increase in power of the engines fitted to airships has made +steady progress from the outset; Haenlein's engine developed +about 6 horse-power; the Santos-Dumont airship of 1898 was +propelled by a motor of 4 horse-power; in 1902 the Lebaudy +airship was fitted with an engine of 40 horse-power, while, in +1910, the Lebaudy brothers fitted an engine of nearly 300 +horsepower to the airship they were then constructing--1,400 +horse-power was common in the airships of the War period, and +the later British rigids developed yet more. + +Before passing on to consideration of the petrol-driven type of +engine, it is necessary to accord brief mention to the dirigible +constructed in 1884 by Gaston and Albert Tissandier, who at +Grenelle, France, achieved a directed flight in a wind of 8 +miles an hour, obtaining their power for the propeller from 1 1/3 +horse-power Siemens electric motor, which weighed 121 lbs. and +took its current from a bichromate battery weighing 496 lbs. A +two-bladed propeller, 9 feet in diameter, was used, and the +horse-power output was estimated to have run up to 1 1/2 as the +dirigible successfully described a semicircle in a wind of 8 +miles an hour, subsequently making headway transversely to a wind +of 7 miles an hour. The dirigible with which this motor was used +was of the conventional pointed-end type, with a length of 92 +feet, diameter of 30 feet, and capacity of 37,440 cubic feet of +gas. Commandant Renard, of the French army balloon corps, +followed up Tissandier's attempt in the next year--1885--making a +trip from Chalais-Meudon to Paris and returning to the point of +departure quite successfully. In this case the motive power was +derived from an electric plant of the type used by the +Tissandiers, weighing altogether 1,174 lbs., and developing 9 +horsepower. A speed of 14 miles an hour was attained with this +dirigible, which had a length of 165 feet, diameter of 27 feet, +and capacity of 65,836 cubic feet of gas. + +Reverting to the petrol-fed type again, it is to be noted that +Santos-Dumont was practically the first to develop the use of +the ordinary automobile engine for air work--his work is of such +importance that it has been considered best to treat of it as +one whole, and details of the power plants are included in the +account of his experiments. Coming to the Lebaudy brothers and +their work, their engine of 1902 was a 40 horse-power Daimler, +four-cylindered; it was virtually a large edition of the Daimler +car engine, the arrangement of the various details being on the +lines usually adopted for the standard Daimler type of that +period. The cylinders were fully water-jacketed, and no special +attempt toward securing lightness for air work appears to have +been made. + +The fining down of detail that brought weight to such limits as +would fit the engine for work with heavier-than-air craft +appears to have waited for the brothers Wright. Toward the end +of 1903 they fitted to their first practicable flying machine the +engine which made the historic first aeroplane flight; this +engine developed 30 horse-power, and weighed only about 7 lbs. +per horse-power developed, its design and workmanship being far +ahead of any previous design in this respect, with the exception +of the remarkable engine, designed by Manly, installed in +Langley's ill-fated aeroplane--or 'aerodrome,' as he preferred to +call it--tried in 1903. + +The light weight of the Wright brothers' engine did not +necessitate a high number of revolutions per minute to get the +requisite power; the speed was only 1,300 revolutions per +minute, which, with a piston stroke of 3.94 inches, was quite +moderate. Four cylinders were used, the cylinder diameter being +4.42 inches; the engine was of the vertical type, arranged to +drive two propellers at a rate of about 350 revolutions per +minute, gearing being accomplished by means of chain drive from +crank-shaft end to propeller spindle. + +The methods adopted by the Wrights for obtaining a light-weight +engine were of considerable interest, in view of the fact that +the honour of first achieving flight by means of the driven plane +belongs to them--unless Ader actually flew as he claimed. The +cylinders of this first Wright engine were separate castings of +steel, and only the barrels were jacketed, this being done by +fixing loose, thin aluminium covers round the outside of each +cylinder. The combustion head and valve pockets were cast +together with the cylinder barrel, and were not water cooled. +The inlet valves were of the automatic type, arranged on the tops +of the cylinders, while the exhaust valves were also overhead, +operated by rockers and push-rods. The pistons and piston rings +were of the ordinary type, made of cast-iron, and the connecting +rods were circular in form, with a hole drilled down the middle +of each to reduce the weight. + +Necessity for increasing power and ever lighter weight in +relation to the power produced has led to the evolution of a +number of different designs of internal combustion engines. It +was quickly realised that increasing the number of cylinders on +an engine was a better way of getting more power than that of +increasing the cylinder diameter, as the greater number of +cylinders gives better torque-even turning effect--as well as +keeping down the weight--this latter because the bigger +cylinders must be more stoutly constructed than the small sizes; +this fact has led to the construction of engines having as many +as eighteen cylinders, arranged in three parallel rows in order +to keep the length of crankshaft within reasonable limits. The +aero engine of to-day may, roughly, be divided into four +classes: these are the V type, in which two rows of cylinders +are set parallel at a certain angle to each other; the radial +type, which consists of cylinders arranged radially and +remaining stationary while the crankshaft revolves; the rotary, +where the cylinders are disposed round a common centre and +revolve round a stationary shaft, and the vertical type, of four +or six cylinders--seldom more than this--arranged in one row. A +modification of the V type is the eighteen-cylindered engine-- +the Sunbeam is one of the best examples--in which three rows of +cylinders are set parallel to each other, working on a common +crankshaft. The development these four types started with that +of the vertical--the simplest of all; the V, radial, and rotary +types came after the vertical, in the order given. + +The evolution of the motor-car led to the adoption of the +vertical type of internal combustion engine in preference to any +other, and it followed naturally that vertical engines should be +first used for aeroplane propulsion, as by taking an engine that +had been developed to some extent, and adapting it to its new +work, the problem of mechanical flight was rendered easier than +if a totally new type had had to be evolved. It was quickly +realised--by the Wrights, in fact-that the minimum of weight per +horse-power was the prime requirement for the successful +development of heavier-than-air machines, and at the same time +it was equally apparent that the utmost reliability had to be +obtained from the engine, while a third requisite was economy, +in order to reduce the weight of petrol necessary for flight. + +Daimler, working steadily toward the improvement of the internal +combustion engine, had made considerable progress by the end of +last century. His two-cylinder engine of 1897 was approaching +to the present-day type, except as regards the method of +ignition; the cylinders had 3.55 inch diameter, with a 4.75 inch +piston stroke, and the engine was rated at 4.5 brake horse-power, +though it probably developed more than this in actual running at +its rated speed of 800 revolutions per minute. Power was limited +by the inlet and exhaust passages, which, compared with +present-day practice, were very small. The heavy castings of +which the engine was made up are accounted for by the necessity +for considering foundry practice of the time, for in 1897 +castings were far below the present-day standard. The crank-case +of this two-cylinder vertical Daimler engine was the only part +made of aluminium, and even with this no attempt was made to +attain lightness, for a circular flange was cast at the bottom to +form a stand for the engine during machining and erection. The +general design can be followed from the sectional views, and +these will show, too, that ignition was by means of a hot tube on +the cylinder head, which had to be heated with a blow-lamp before +starting the engine. With all its well known and hated troubles, +at that time tube ignition had an advantage over the magneto, and +the coil and accumulator system, in reliability; sparking plugs, +too, were not so reliable then as they are now. Daimler fitted a +very simple type of carburettor to this engine, consisting only +of a float with a single jet placed in the air passage. It may +be said that this twin-cylindered vertical was the first of the +series from which has been evolved the Mercedes-Daimler car and +airship engines, built in sizes up to and even beyond 240 +horse-power. + +In 1901 the development of the petrol engine was still so slight +that it did not admit of the construction, by any European +maker, of an engine weighing less than 12 lbs. per horse-power. +Manly, working at the instance of Professor Langley, produced a +five-cylindered radial type engine, in which both the design and +workmanship showed a remarkable advance in construction. At 950 +revolutions per minute it developed 52.4 horse-power, weighing +only 2.4 pounds per horse-power; it was a very remarkable +achievement in engine design, considering the power developed in +relation to the total weight, and it was, too, an interruption +in the development of the vertical type which showed that there +were other equally great possibilities in design. + +In England, the first vertical aero-engine of note was that +designed by Green, the cylinder dimensions being 4.15 inch +diameter by 4.75 stroke--a fairly complete idea of this engine +can be obtained from the accompanying diagrams. At a speed of +1,160 revolutions per minute it developed 35 brake horse-power, +and by accelerating up to 1,220 revolutions per minute a maximum +of 40 brake horse-power could be obtained--the first-mentioned +was the rated working speed of the engine for continuous runs. +A flywheel, weighing 23.5 lbs., was fitted to the engine, and +this, together with the ignition system, brought the weight up +to 188 lbs., giving 5.4 lbs. per horse-power. In comparison with +the engine fitted to the Wrights' aeroplane a greater power was +obtained from approximately the same cylinder volume, and an +appreciable saving in weight had also been effected. The +illustration shows the arrangement of the vertical valves at the +top of the cylinder and the overhead cam shaft, while the +position of the carburettor and inlet pipes can be also seen. +The water jackets were formed by thin copper casings, each +cylinder being separate and having its independent jacket rigidly +fastened to the cylinder at the top only, thus allowing for free +expansion of the casing; the joint at the bottom end was formed +by sliding the jacket over a rubber ring. Each cylinder was +bolted to the crank-case and set out of line with the crankshaft, +so that the crank has passed over the upper dead centre by the +time that the piston is at the top of its stroke when receiving +the full force of fuel explosion. The advantage of this +desaxe setting is that the pressure in the cylinder acts on the +crank-pin with a more effective leverage during that part of the +stroke when that pressure is highest, and in addition the side +pressure of the piston on the cylinder wall, due to the thrust of +the connecting rod, is reduced. Possibly the charging of the +cylinder is also more complete by this arrangement, owing to the +slower movement of the piston at the bottom of its stroke +allowing time for an increased charge of mixture to enter the +cylinder. + +A 60 horse-power engine was also made, having four vertical +cylinders, each with a diameter of 5.5 inches and stroke of 5.75 +inches, developing its rated power at 1,100 revolutions per +minute. By accelerating up to 1,200 revolutions per minute 70 +brake horsepower could be obtained, and a maximum of 80 brake +horse-power was actually attained with the type. The flywheel, +fitted as with the original 35 horse-power engine, weighed 37 +lbs.; with this and with the ignition system the total weight of +the engine was only 250 lbs., or 4.2 lbs. per horse-power at +the normal rating. In this design, however, low weight in +relation to power was not the ruling factor, for Green gave more +attention to reliability and economy of fuel consumption, which +latter was approximately 0.6 pint of petrol per brake +horse-power per hour. Both the oil for lubricating the bearings +and the water for cooling the cylinders were circulated by +pumps, and all parts of the valve gear, etc., were completely +enclosed for protection from dust. + +A later development of the Green engine was a six-cylindered +vertical, cylinder dimensions being 5.5 inch diameter by 6 inch +stroke, developing 120 brake horsepower when running at 1,250 +revolutions per minute. The total weight of the engine with +ignition system 398 was 440 lbs., or 3.66 lbs. per horse-power. +One of these engines was used on the machine which, in 1909, won +the prize of L1,000 for the first circular mile flight, and it +may be noted, too, that S. F. Cody, making the circuit of England +in 1911, used a four-cylinder Green engine. Again, it was a +Green engine that in 1914 won the L5,000 prize offered for the +best aero engine in the Naval and Military aeroplane engine +competition. + +Manufacture of the Green engines, in the period of the War, had +standardised to the production of three types. Two of these were +six-cylinder models, giving respectively 100 and 150 brake +horse-power, and the third was a twelve-cylindered model rated +at 275 brake horse-power. + +In 1910 J. S. Critchley compiled a list showing the types of +engine then being manufactured; twenty-two out of a total of +seventy-six were of the four-cylindered vertical type, and in +addition to these there were two six-cylindered verticals. +The sizes of the four-cylinder types ranged from 26 up to 118 +brake horse-power; fourteen of them developed less than 50 +horse-power, and only two developed over 100 horse-power. + +It became apparent, even in the early stages of heavier-than-air +flying, that four-cylinder engines did not produce the even +torque that was required for the rotation of the power shaft, +even though a flywheel was fitted to the engine. With this type +of engine the breakage of air-screws was of frequent occurrence, +and an engine having a more regular rotation was sought, both +for this and to avoid the excessive vibration often experienced +with the four-cylinder type. Another, point that forced itself +on engine builders was that the increased power which was +becoming necessary for the propulsion of aircraft made an +increase in the number of cylinders essential, in order to obtain +a light engine. An instance of the weight reduction obtainable +in using six cylinders instead of four is shown in Critchley's +list, for one of the four-cylinder engines developed 118.5 brake +horse-power and weighed 1,100 lbs., whereas a six-cylinder engine +by the same manufacturer developed 117.5 brake horse-power with a +weight of 880 lbs., the respective cylinder dimensions being +7.48 diameter by 9.06 stroke for the four-cylinder engine, and +6.1 diameter by 7.28 stroke for the six-cylinder type. + +A list of aeroplane engines, prepared in 1912 by Graham Clark, +showed that, out of the total number of 112 engines then +being manufactured, forty-two were of the vertical type, and of +this number twenty-four had four-cylinders while sixteen were +six-cylindered. The German aeroplane engine trials were held a +year later, and sixty-six engines entered the competition, +fourteen of these being made with air-cooled cylinders. All of +the ten engines that were chosen for the final trials were of +the water-cooled type, and the first place was won by a Benz +four-cylinder vertical engine which developed 102 brake +horse-power at 1,288 revolutions per minute. The cylinder +dimensions of this engine were 5.1 inch diameter by 7.1 inch +stroke, and the weight of the engine worked out at 3.4 lbs. per +brake horse-power. During the trials the full-load petrol +consumption was 0.53 pint per horse-power per hour, and the +amount of lubricating oil used was 0.0385 pint per brake +horse-power per hour. In general construction this Benz engine +was somewhat similar to the Green engine already described; the +overhead valves, fitted in the tops of the cylinders, were +similarly arranged, as was the cam-shaft; two springs were +fitted to each of the valves to guard against the possibility of +the engine being put out of action by breakage of one of the +springs, and ignition was obtained by two high-tension magnetos +giving simultaneous sparks in each cylinder by means of two +sparking plugs--this dual ignition reduced the possibility of +ignition troubles. The cylinder jackets were made of welded +sheet steel so fitted around the cylinder that the head was also +water-cooled, and the jackets were corrugated in the middle to +admit of independent expansion. Even the lubrication system was +duplicated, two sets of pumps being used, one to circulate the +main supply of lubricating oil, and the other to give a +continuous supply of fresh oil to the bearings, so that if the +supply from one pump failed the other could still maintain +effective lubrication. + +Development of the early Daimler type brought about the +four-cylinder vertical Mercedes-Daimler engine of 85 horse-power, +with cylinders of 5.5 diameter with 5.9 inch stroke, the +cylinders being cast in two pairs. The overhead arrangement of +valves was adopted, and in later designs push-rods were +eliminated, the overhead cam-shaft being adopted in their place. +By 1914 the four-cylinder Mercedes-Daimler had been partially +displaced from favour by a six-cylindered model, made in two +sizes; the first of these gave a nominal brake horse-power of 80, +having cylinders of 4.1 inches diameter by 5.5 inches stroke; the +second type developed 100 horse-power with cylinders 4.7 inches +in diameter and 5.5 inches stroke, both types being run at 1,200 +revolutions per minute. The cylinders of both these types were +cast in pairs, and, instead of the water jackets forming part of +the casting, as in the design of the original four-cylinder +Mercedes-Daimler engine, they were made of steel welded to +flanges on the cylinders. Steel pistons, fitted with cast-iron +rings, were used, and the overhead arrangement of valves and +cam-shaft was adopted. About 0.55 pint per brake horse-power per +hour was the usual fuel consumption necessary to full load +running, and the engine was also economical as regards the +consumption of lubricating oil, the lubricating system being +'forced' for all parts, including the cam-shaft. The shape of +these engines was very well suited for work with aircraft, being +narrow enough to admit of a streamline form being obtained, while +all the accessories could be so mounted as to produce little or +no wind resistance, and very little obstruction to the pilot's +view. + +The eight-cylinder Mercedes-Daimler engine, used for airship +propulsion during the War, developed 240 brake horse-power at +1,100 revolutions per minute; the cylinder dimensions were 6.88 +diameter by 6.5 stroke--one of the instances in which the short +stroke in relation to bore was very noticeable. + +Other instances of successful vertical design-the types already +detailed are fully sufficient to give particulars of the type +generally--are the Panhard, Chenu, Maybach, N.A.G., Argus, +Mulag, and the well-known Austro-Daimler, which by 1917 was +being copied in every combatant country. There are also the +later Wright engines, and in America the Wisconsin six-cylinder +vertical, weighing well under 4 lbs. per horse-power, is +evidence of the progress made with this first type of aero +engine to develop. + + + +II. THE VEE TYPE + +An offshoot from the vertical type, doubling the power of this +with only a very slight--if any--increase in the length of +crankshaft, the Vee or diagonal type of aero engine leaped to +success through the insistent demand for greater power. +Although the design came after that of the vertical engine, by +1910, according to Critchley's list of aero engines, there +were more Vee type engines being made than any other type, +twenty-five sizes being given in the list, with an average +rating of 57.4 brake horse-power. + +The arrangement of the cylinders in Vee form over the +crankshaft, enabling the pistons of each pair of opposite +cylinders to act upon the same crank pin, permits of a very +short, compact engine being built, and also permits of reduction +of the weight per horsepower, comparing this with that of the +vertical type of engine, with one row of cylinders. Further, at +the introduction of this type of engine it was seen that +crankshaft vibration, an evil of the early vertical engines, was +practically eliminated, as was the want of longitudinal +stiffness that characterised the higher-powered vertical +engines. + +Of the Vee type engines shown in Critchley's list in 1910 +nineteen different sizes were constructed with eight cylinders, +and with horse-powers ranging from thirty to just over the +hundred; the lightest of these weighed 2.9 lbs. per +horse-power--a considerable advance in design on the average +vertical engine, in this respect of weight per horse-power. +There were also two sixteen-cylinder engines of Vee design, the +larger of which developed 134 horse-power with a weight of only 2 +lbs. per brake horse-power. Subsequent developments have +indicated that this type, with the further development from it of +the double-Vee, or engine with three rows of cylinders, is likely +to become the standard design of aero engine where high powers +are required. The construction permits of placing every part so +that it is easy of access, and the form of the engine implies +very little head resistance, while it can be placed on the +machine--supposing that machine to be of the single-engine +type--in such a way that the view of the pilot is very little +obstructed while in flight. + +An even torque, or great uniformity of rotation, is transmitted +to the air-screw by these engines, while the design also permits +of such good balance of the engine itself that vibration is +practically eliminated. The angle between the two rows of +cylinders is varied according to the number of cylinders, in +order to give working impulses at equal angles of rotation and +thus provide even torque; this angle is determined by dividing +the number of degrees in a circle by the number of cylinders in +either row of the engine. In an eight-cylindered Vee type +engine, the angle between the cylinders is 90 degrees; if it is +a twelve-cylindered engine, the angle drops to 60 degrees. + +One of the earliest of the British-built Vee type engines was an +eight-cylinder 50 horse-power by the Wolseley Company, +constructed in 1908 with a cylinder bore of 3.75 inches and +stroke of 5 inches, running at a normal speed of 1,350 +revolutions per minute. With this engine, a gearing was +introduced to enable the propeller to run at a lower speed than +that of the engine, the slight loss of efficiency caused by the +friction of the gearing being compensated by the slower speed of +the air-screw, which had higher efficiency than would have been +the case if it had been run at the engine speed. The ratio of +the gearing--that is, the speed of the air-screw relatively to +that of the engine, could be chosen so as to suit exactly the +requirements of the air-screw, and the gearing itself, on this +engine, was accomplished on the half-speed shaft actuating the +valves. + +Very soon after this first design had been tried out, a second +Vee type engine was produced which, at 1,200 revolutions per +minute, developed 60 horse-power; the size of this engine was +practically identical with that of its forerunner, the only +exception being an increase of half an inch in the cylinder +stroke--a very long stroke of piston in relation to the bore of +the cylinder. In the first of these two engines, which was +designed for airship propulsion, the weight had been about 8 +lbs. per brake horse-power, no special attempt appearing to +have been made to fine down for extreme lightness; in this 60 +horse-power design, the weight was reduced to 6.1 lbs. per +horse-power, counting the latter as normally rated; the +engine actually gave a maximum of 75 brake horse-power, reducing +the ratio of weight to power very considerably below the figure +given. + +The accompanying diagram illustrates a later Wolseley model, end +elevation, the eight-cylindered 120 horse-power Vee type aero +engine of the early war period. With this engine, each crank +pin has two connecting rods bearing on it, these being placed +side by side and connected to the pistons of opposite cylinders +and the two cylinders of the pair are staggered by an amount +equal to the width of the connecting rod bearing, to afford +accommodation for the rods. The crankshaft was a nickel chrome +steel forging, machined hollow, with four crank pins set at 180 +degrees to each other, and carried in three bearings lined with +anti-friction metal. The connecting rods were made of tubular +nickel chrome steel, and the pistons of drawn steel, each being +fitted with four piston rings. Of these the two rings nearest to +the piston head were of the ordinary cast-iron type, while the +others were of phosphor bronze, so arranged as to take the side +thrust of the piston. The cylinders were of steel, arranged in +two groups or rows of four, the angular distance between them +being 90 degrees. In the space above the crankshaft, between the +cylinder rows, was placed the valve-operating mechanism, together +with the carburettor and ignition system, thus rendering this a +very compact and accessible engine. The combustion heads of the +cylinders were made of cast-iron, screwed into the steel cylinder +barrels; the water-jacket was of spun aluminium, with one end +fitting over the combustion head and the other free to slide on +the cylinder; the water-joint at the lower end was made tight by +a Dermatine ring carried between small flanges formed on the +cylinder barrel. Overhead valves were adopted, and in order to +make these as large as possible the combustion chamber was made +slightly larger in diameter than the cylinder, and the valves set +at an angle. Dual ignition was fitted in each cylinder, coil and +accumulator being used for starting and as a reserve in case of +failure of the high-tension magneto system fitted for normal +running. There was a double set of lubricating pumps, ensuring +continuity of the oil supply to all the bearings of the engine. + +The feature most noteworthy in connection with the running of +this type of engine was its flexibility; the normal output of +power was obtained with 1,150 revolutions per minute of the +crankshaft, but, by accelerating up to 1,400 revolutions, a +maximum of 147 brake horse-power could be obtained. The weight +was about 5 lbs. per horse-power, the cylinder dimensions being +5 inches bore by 7 inches stroke. Economy in running was +obtained, the fuel consumption being 0.58 pint per brake +horse-power per hour at full load, with an expenditure of about +0.075 pint of lubricating oil per brake horse-power per hour. + +Another Wolseley Vee type that was standardised was a 90 +horse-power eight-cylinder engine running at 1,800 revolutions +per minute, with a reducing gear introduced by fitting the air +screw on the half-speed shaft. First made semi-cooled--the +exhaust valve was left air-cooled, and then entirely +water-jacketed--this engine demonstrated the advantage of full +water cooling, for under the latter condition the same power was +developed with cylinders a quarter of an inch less in diameter +than in the semi-cooled pattern; at the same time the weight was +brought down to 4 1/2 lbs. per horsepower. + +A different but equally efficient type of Vee design was the +Dorman engine, of which an end elevation is shown; this +developed 80 brake horse-power at a speed of 1,300 revolutions +per minute, with a cylinder bore of 5 inches; each cylinder was +made in cast-iron in one piece with the combustion chamber, the +barrel only being water-jacketed. Auxiliary exhaust ports were +adopted, the holes through the cylinder wall being uncovered by +the piston at the bottom of its stroke--the piston, 4.75 inches +in length, was longer than its stroke, so that these ports were +covered when it was at the top of the cylinder. The exhaust +discharged through the ports into a belt surrounding the +cylinder, the belts on the cylinders being connected so that the +exhaust gases were taken through a single pipe. The air was +drawn through the crank case, before reaching the carburettor, +this having the effect of cooling the oil in the crank case as +well as warming the air and thus assisting in vaporising the +petrol for each charge of the cylinders. The inlet and exhaust +valves were of the overhead type, as may be gathered from the +diagram, and in spite of cast-iron cylinders being employed a +light design was obtained, the total weight with radiator, +piping, and water being only 5.5 lbs. per horse-power. + +Here was the antithesis of the Wolseley type in the matter of +bore in relation to stroke; from about 1907 up to the beginning +of the war, and even later, there was controversy as to which +type--that in which the bore exceeded the stroke, or vice +versa--gave greater efficiency. The short-stroke enthusiasts +pointed to the high piston speed of the long-stroke type, while +those who favoured the latter design contended that full power +could not be obtained from each explosion in the short-stroke +type of cylinder. It is now generally conceded that the +long-stroke engine yields higher efficiency, and in addition to +this, so far as car engines are concerned, the method of rating +horse-power in relation to bore without taking stroke into +account has given the long-stroke engine an advantage, actual +horse-power with a long stroke engine being in excess of the +nominal rating. This may have had some influence on aero engine +design, but, however this may have been, the long-stroke engine +has gradually come to favour, and its rival has taken second +place. + +For some time pride of place among British Vee type engines was +held by the Sunbeam Company, which, owing to the genius of Louis +Coatalen, together with the very high standard of construction +maintained by the firm, achieved records and fame in the middle +and later periods of the war. Their 225 horse-power +twelve-cylinder engine ran at a normal speed of 2,000 revolutions +per minute; the air screw was driven through gearing at half this +speed, its shaft being separate from the timing gear and carried +in ball-bearings on the nose-piece of the engine. The cylinders +were of cast-iron, entirely water-cooled; a thin casing formed +the water-jacket, and a very light design was obtained, the +weight being only 3.2 lbs. per horse-power. The first engine of +Sunbeam design had eight cylinders and developed 150 horse-power +at 2,000 revolutions per minute; the final type of Vee design +produced during the war was twelve-cylindered, and yielded 310 +horse-power with cylinders 4.3 inches bore by 6.4 inches stroke. +Evidence in favour of the long-stroke engine is afforded in this +type as regards economy of working; under full load, working at +2,000 revolutions per minute, the consumption was 0.55 pints of +fuel per brake horse-power per hour, which seems to indicate that +the long stroke permitted of full use being made of the power +resulting from each explosion, in spite of the high rate of speed +of the piston. + +Developing from the Vee type, the eighteen-cylinder 475 brake +horse-power engine, designed during the war, represented +for a time the limit of power obtainable from a single plant. +It was water-cooled throughout, and the ignition to each +cylinder was duplicated; this engine proved fully efficient, and +economical in fuel consumption. It was largely used for +seaplane work, where reliability was fully as necessary as high +power. + +The abnormal needs of the war period brought many British firms +into the ranks of Vee-type engine-builders, and, apart from +those mentioned, the most notable types produced are the +Rolls-Royce and the Napier. The first mentioned of these firms, +previous to 1914 had concentrated entirely on car engines, and +their very high standard of production in this department of +internal combustion engine work led, once they took up the +making of aero engines, to extreme efficiency both of design and +workmanship. The first experimental aero engine, of what became +known as the 'Eagle' type, was of Vee design--it was completed +in March of 1915--and was so successful that it was standardised +for quantity production. How far the original was from the +perfection subsequently ascertained is shown by the steady +increase in developed horse-power of the type; originally +designed to develop 200 horse-power, it was developed and +improved before its first practical trial in October of 1915, +when it developed 255 horsepower on a brake test. Research and +experiment produced still further improvements, for, without any +enlargement of the dimensions, or radical alteration in design, +the power of the engine was brought up to 266 horse-power by +March of 1916, the rate of revolutions of 1,800 per minute being +maintained throughout. July, 1916 gave 284 horse-power; by the +cud of the year this had been increased to 322 horse-power; by +September of 1917 the increase was to 350 horse-power, and by +February of 1918 then 'Eagle' type of engine was rated at 360 +horse-power, at which standard it stayed. But there is no more +remarkable development in engine design than this, a 75 per cent +increase of power in the same engine in a period of less than +three years. + +To meet the demand for a smaller type of engine for use on +training machines, the Rolls-Royce firm produced the 'Hawk' +Vee-type engine of 100 horsepower, and, intermediately between +this and the 'Eagle,' the 'Falcon' engine came to being with an +original rated horse-power of 205 at 1,800 revolutions per +minute, in April of 1916. Here was another case of growth of +power in the same engine through research, almost similar to +that of the 'Eagle' type, for by July of 1918 the 'Falcon' was +developing 285 horse-power with no radical alteration of +design. Finally, in response to the constant demand for +increase of power in a single plant, the Rolls-Royce company +designed and produced the 'Condor' type of engine, which yielded +600 horse-power on its first test in August of 1918. The +cessation of hostilities and consequent falling off in the +demand for extremely high-powered plants prevented the 'Condor' +being developed to its limit, as had been the 'Falcon' and +'Eagle' types. + +The 'Eagle 'engine was fitted to the two Handley-Page +aeroplanes--which made flights from England to India--it was +virtually standard on the Handley-Page bombers of the later War +period, though to a certain extent the American 'Liberty' engine +was also used. Its chief record, however, is that of being the +type fitted to the Vickers-Vimy aeroplane which made the first +Atlantic flight, covering the distance of 1,880 miles at a speed +averaging 117 miles an hour. + +The Napier Company specialised on one type of engine from the +outset, a power plant which became known as the 'Lion' engine, +giving 450 horse-power with twelve cylinders arranged in three +rows of four each. Considering the engine as 'dry,' or without +fuel and accessories, an abnormally light weight per +horse-power--only 1.89 lbs.--was attained when running at the +normal rate of revolution. The cylinders and water-jackets are +of steel, and there is fitted a detachable aluminium cylinder +head containing inlet and exhaust valves and valve actuating +mechanism; pistons are of aluminium alloy, and there are two +inlet and two exhaust valves to each cylinder, the whole of the +valve mechanism being enclosed in an oil-tight aluminium case. +Connecting rods and crankshaft are of steel, the latter being +machined from a solid steel forging and carried in five roller +bearings and one plain bearing at the forward end. The front end +of the crank-case encloses reduction gear for the propeller +shaft, together with the shaft and bearings. There are two +suction and one pressure type oil pumps driven through gears at +half-engine speed, and two 12 spark magnetos, giving 2 sparks in +each cylinder. + +The cylinders are set with the central row vertical, and the two +side rows at angles of 60 degrees each; cylinder bore is 5 1/2 +inches, and stroke 5 1/8 inches; the normal rate of revolution +is 1,350 per minute, and the reducing gear gives one revolution +of the propeller shaft to 1.52 revolutions of crankshaft. Fuel +consumption is 0.48lbs. of fuel per brake horse-power hour at +full load, and oil consumption is 0.020 lbs. per brake horsepower +hour. The dry weight of the engine, complete with propeller +boss, carburettors, and induction pipes, is 850 lbs., and the +gross weight in running order, with fuel and oil for six hours +working, is 2,671 lbs., exclusive of cooling water. + +To this engine belongs an altitude record of 30,500 feet, made at +Martlesham, near Ipswich, on January 2nd, 1919, by Captain Lang, +R.A.F., the climb being accomplished in 66 minutes 15 seconds. +Previous to this, the altitude record was held by an Italian +pilot, who made 25,800 feet in an hour and 57 minutes in 1916. +Lang's climb was stopped through the pressure of air, at the +altitude he reached, being insufficient for driving the small +propellers on the machine which worked the petrol and oil pumps, +or he might have made the height said to have been attained by +Major Schroeder on February 27th, 1920, at Dayton, Ohio. +Schroeder is said to have reached an altitude of 36,020 feet on a +Napier biplane, and, owing to failure of the oxygen supply, to +have lost consciousness, fallen five miles, righted his machine +when 2,000 feet in the air, and alighted successfully. Major +Schroeder is an American. + +Turning back a little, and considering other than British design +of Vee and double-Vee or 'Broad arrow' type of engine, the +Renault firm from the earliest days devoted considerable +attention to the development of this type, their air-cooled +engines having been notable examples from the earliest days of +heavier-than-air machines. In 1910 they were making three sizes +of eight-cylindered Vee-type engines, and by 1915 they had +increased to the manufacture of five sizes, ranging from 25 to +100 brake horse-power, the largest of the five sizes having +twelve cylinders but still retaining the air-cooled principle. +The De Dion firm, also, made Vee-type engines in 1914, being +represented by an 80 horse-power eight-cylindered engine, +air-cooled, and a 150 horse-power, also of eight cylinders, +water-cooled, running at a normal rate of 1,600 revolutions per +minute. Another notable example of French construction was the +Panhard and Levassor 100 horse-power eight-cylinder Vee engine, +developing its rated power at 1,500 revolutions per minute, and +having the--for that time--low weight of 4.4 lbs. per +horse-power. + +American Vee design has followed the British fairly cclosely; +the Curtiss Company produced originally a 75 horse-power +eight-cylinder Vee type running at 1,200 revolutions per minute, +supplementing this with a 170 horse-power engine running at +1,600 revolutions per minute, and later with a twelve-cylinder +model Vee type, developing 300 horse-power at 1,500 revolutions +per minute, with cylinder bore of 5 inches and stroke of 7 +inches. An exceptional type of American design was the Kemp Vee +engine of 80 horse-power in which the cylinders were cooled by a +current of air obtained from a fan at the forward end of the +engine. With cylinders of 4.25 inches bore and 4.75 inches +stroke, the rater power was developed at 1,150 revolutions per +minute, and with the engine complete the weight was only 4.75 +lbs. per horse-power. + + + +III. THE RADIAL TYPE + +The very first successful design of internal combustion aero +engine made was that of Charles Manly, who built a five-cylinder +radial engine in 1901 for use with Langley's 'aerodrome,' as the +latter inventor decided to call what has since become known as +the aeroplane. Manly made a number of experiments, and finally +decided on radial design, in which the cylinders are so rayed +round a central crank-pin that the pistons act successively upon +it; by this arrangement a very short and compact engine is +obtained, with a minimum of weight, and a regular crankshaft +rotation and perfect balance of inertia forces. + +When Manly designed his radial engine, high speed internal +combustion engines were in their infancy, and the difficulties in +construction can be partly realised when the lack of +manufacturing methods for this high-class engine work, and the +lack of experimental data on the various materials, are taken +into account. During its tests, Manly's engine developed 52.4 +brake horsepower at a speed of 950 revolutions per minute, with +the remarkably low weight of only 2.4 lbs. per horsepower; this +latter was increased to 3.6 lbs. when the engine was completed by +the addition of ignition system, radiator, petrol tank, and all +accessories, together with the cooling water for the cylinders. + +In Manly's engine, the cylinders were of steel, machined outside +and inside to 1/16 of an inch thickness; on the side of cylinder, +at the top end, the valve chamber was brazed, being machined +from a solid forging, The casing which formed the water-jacket +was of sheet steel, 1/50 of an inch in thickness, and this also +was brazed on the cylinder and to the valve chamber. Automatic +inlet valves were fitted, and the exhaust valves were operated +by a cam which had two points, 180 degrees apart; the cam was +rotated in the opposite direction to the engine at one-quarter +engine speed. Ignition was obtained by using a one-spark coil +and vibrator for all cylinders, with a distributor to select the +right cylinder for each spark--this was before the days of the +high-tension magneto and the almost perfect ignition systems that +makers now employ. The scheme of ignition for this engine was +originated by Manly himself, and he also designed the sparking +plugs fitted in the tops of the cylinders. Through fear of +trouble resulting if the steel pistons worked on the steel +cylinders, cast iron liners were introduced in the latter, 1/16 +of an inch thick. + +The connecting rods of this engine were of virtually the same +type as is employed on nearly all modern radial engines. The +rod for one cylinder had a bearing along the whole of the crank +pin, and its end enclosed the pin; the other four rods had +bearings upon the end of the first rod, and did not touch the +crank pin. The accompanying diagram shows this construction, +together with the means employed for securing the ends of the +four rods--the collars were placed in position after the rods +had been put on. The bearings of these rods did not receive any +of the rubbing effect due to the rotation of the crank pin, the +rubbing on them being only that of the small angular displacement +of the rods during each revolution; thus there was no difficulty +experienced with the lubrication. + +Another early example of the radial type of engine was the +French Anzani, of which type one was fitted to the machine with +which Bleriot first crossed the English Channel--this was of 25 +horse-power. The earliest Anzani engines were of the +three-cylinder fan type, one cylinder being vertical, and the +other two placed at an angle of 72 degrees on each side, as the +possibility of over-lubrication of the bottom cylinders was +feared if a regular radial construction were adopted. In order +to overcome the unequal balance of this type, balance weights +were fitted inside the crank case. + +The final development of this three-cylinder radial was the 'Y' +type of engine, in which the cylinders were regularly disposed +at 120 degrees apart, the bore was 4.1, stroke 4.7 inches, and +the power developed was 30 brake horse-power at 1,300 +revolutions per minute. + +Critchley's list of aero engines being constructed in 1910 shows +twelve of the radial type, with powers of between 14 and 100 +horse-power, and with from three to ten cylinder--this last is +probably the greatest number of cylinders that can be +successfully arranged in circular form. Of the twelve types of +1910, only two were water-cooled, and it is to be noted that +these two ran at the slowest speeds and had the lowest weight per +horse-power of any. + +The Anzani radial was considerably developed special attention +being paid to this type by its makers and by 1914 the Anzani +list comprised seven different sizes of air-cooled radials. Of +these the largest had twenty cylinders, developing 200 brake +horse-power--it was virtually a double radial--and the smallest +was the original 30 horse-power three-cylinder design. A +six-cylinder model was formed by a combination of two groups of +three cylinders each, acting upon a double-throw crankshaft; the +two crank pins were set at 180 degrees to each other, and the +cylinder groups were staggered by an amount equal to the +distance between the centres of the crank pins. Ten-cylinder +radial engines are made with two groups of five cylinders acting +upon two crank pins set at 180 degrees to each other, the largest +Anzani 'ten' developed 125 horsepower at 1,200 revolutions per +minute, the ten cylinders being each 4.5 inches in bore with +stroke of 5.9 inches, and the weight of the engine being 3.7 lbs. +per horse-power. In the 200 horse-power Anzani radial the +cylinders are arranged in four groups of five each, acting on two +crank pins. The bore of the cylinders in this engine is the same +as in the three-cylinder, but the stroke is increased to 5.5 +inches. The rated power is developed at 1,300 revolutions per +minute, and the engine complete weighs 3.4 lbs. per horse-power. + +With this 200 horse-power Anzani, a petrol consumption of as low +as 0.49 lbs. of fuel per brake horse-power per hour has been +obtained, but the consumption of lubricating oil is +compensatingly high, being up to one-fifth of the fuel used. The +cylinders are set desaxe with the crank shaft, and are of +cast-iron, provided with radiating ribs for air-cooling; they are +attached to the crank case by long bolts passing through bosses +at the top of the cylinders, and connected to other bolts at +right angles through the crank case. The tops of the cylinders +are formed flat, and seats for the inlet and exhaust valves are +formed on them. The pistons are cast-iron, fitted with ordinary +cast-iron spring rings. An aluminium crank case is used, being +made in two halves connected together by bolts, which latter also +attach the engine to the frame of the machine. The crankshaft +is of nickel steel, made hollow, and mounted on ball-bearings in +such a manner that practically a combination of ball and plain +bearings is obtained; the central web of the shaft is bent to +bring the centres of the crank pins as close together as +possible, leaving only room for the connecting rods, and the pins +are 180 degrees apart. Nickel steel valves of the cone-seated, +poppet type are fitted, the inlet valves being automatic, and +those for the exhaust cam-operated by means of push-rods. With +an engine having such a number of cylinders a very uniform +rotation of the crankshaft is obtained, and in actual running +there are always five of the cylinders giving impulses to the +crankshaft at the same time. + +An interesting type of pioneer radial engine was the Farcot, in +which the cylinders were arranged in a horizontal plane, with a +vertical crankshaft which operated the air-screw through bevel +gearing. This was an eight-cylinder engine, developing 64 +horse-power at 1,200 revolutions per minute. The R.E.P. type,in +the early days, was a 'fan' engine, but the designer, M. Robert +Pelterie, turned from this design to a seven-cylinder radial, +which at 1,100 revolutions per minute gave 95 horse-power. +Several makers entered into radial engine development in the +years immediately preceding the War, and in 1914 there were some +twenty-two different sizes and types, ranging from 30 to 600 +horse-power, being made, according to report; the actual +construction of the latter size at this time, however, is +doubtful. + +Probably the best example of radial construction up to the +outbreak of War was the Salmson (Canton-Unne) water-cooled, of +which in 1914 six sizes were listed as available. Of these +the smallest was a seven-cylinder 90 horse-power engine, and the +largest, rated at 600 horse-power, had eighteen cylinders. +These engines, during the War, were made under license by the +Dudbridge Ironworks in Great Britain. + +The accompanying diagram shows the construction of the cylinders +in the 200 horse-power size, showing the method of cooling, and +the arrangement of the connecting rods. A patent planetary gear, +also shown in the diagram, gives exactly the same stroke to all +the pistons. The complete engine has fourteen cylinders, of +forged steel machined all over, and so secured to the crank +case that any one can be removed without parting the crank case. +The water-jackets are of spun copper, brazed on to the cylinder, +and corrugated so as to admit of free expansion; the water is +circulated by means of a centrifugal pump. The pistons are of +cast-iron, each fitted with three rings, and the connecting rods +are of high grade steel, machined all over and fitted with +bushes of phosphor bronze; these rods are connected to a central +collar, carried on the crank pin by two ball-bearings. The +crankshaft has a single throw, and is made in two parts to allow +the cage for carrying the big end-pins of the connecting rods to +be placed in position. + +The casing is in two parts, on one of which the brackets for +fixing the engine are carried, while the other part carries the +valve-gear. Bolts secure the two parts together. The +mechanically-operated steel valves on the cylinders are each +fitted with double springs and the valves are operated by rods +and levers. Two Zenith carburettors are fitted on the rear half +of the crank case, and short induction pipes are led to each +cylinder; each of the carburettors is heated by the exhaust +gases. Ignition is by two high-tension magnetos, and a +compressed air self-starting arrangement is provided. Two oil +pumps are fitted for lubricating purposes, one of which forces +oil to the crankshaft and connecting-rod bearings, while the +second forces oil to the valve gear, the cylinders being so +arranged that the oil which flows along the walls cannot flood +the lower cylinders. This engine operates upon a six-stroke +cycle, a rather rare arrangement for internal combustion engines +of the electrical ignition type; this is done in order to obtain +equal angular intervals for the working impulses imparted to the +rotating crankshaft, as the cylinders are arranged in groups of +seven, and all act upon the one crankshaft. The angle, +therefore, between the impulses is 77 1/7 degrees. A diagram is +inset giving a side view of the engine, in order to show the +grouping of the cylinders. + +The 600 horse-power Salmson engine was designed with a view to +fitting to airships, and was in reality two nine-cylindered +engines, with a gear-box connecting them; double air-screws were +fitted, and these were so arranged that either or both of them +might be driven by either or both engines; in addition to this, +the two engines were complete and separate engines as regards +carburation and ignition, etc., so that they could be run +independently of each other. The cylinders were exceptionally +'long stroke,' being 5.9 inches bore to 8.27 inches stroke, and +the rated power was developed at 1,200 revolutions per minute, +the weight of the complete engine being only 4.1 lbs. per +horse-power at the normal rating. + +A type of engine specially devised for airship propulsion is +that in which the cylinders are arranged horizontally instead of +vertically, the main advantages of this form being the reduction +of head resistance and less obstruction to the view of the +pilot. A casing, mounted on the top of the engine, supports the +air-screw, which is driven through bevel gearing from the upper +end of the crankshaft. With this type of engine a better rate +of air-screw efficiency is obtained by gearing the screw down to +half the rate of revolution of the engine, this giving a more +even torque. The petrol consumption of the type is very low, +being only 0.48 lbs. per horse-power per hour, and equal +economy is claimed as regards lubricating oil, a consumption of +as little as 0.04 lbs. per horse-power per hour being claimed. + +Certain American radial engines were made previous to 1914, the +principal being the Albatross six-cylinder engines of 50 and 100 +horse-powers. Of these the smaller size was air-cooled, with +cylinders of 4.5 inches bore and 5 inches stroke, developing the +rated power at 1,230 revolutions per minute, with a weight of +about 5 lbs. per horse-power. The 100 horse-power size had +cylinders of 5.5 inches bore, developing its rated power at 1,230 +revolutions per minute, and weighing only 2.75 lbs. per +horse-power. This engine was markedly similar to the +six-cylindered Anzani, having all the valves mechanically +operated, and with auxiliary exhaust ports at the bottoms of the +cylinders, overrun by long pistons. These Albatross engines had +their cylinders arranged in two groups of three, with each group +of three pistons operating on one of two crank pins, each +180 degrees apart. + +The radial type of engine, thanks to Charles Manly, had the +honour of being first in the field as regards aero work. Its +many advantages, among which may be specially noted the very +short crankshaft as compared with vertical, Vee, or 'broad arrow' +type of engine, and consequent greater rigidity, ensure it +consideration by designers of to-day, and render it certain that +the type will endure. Enthusiasts claim that the 'broad arrow' +type, or Vee with a third row of cylinders inset between the +original two, is just as much a development from the radial +engine as from the vertical and resulting Vee; however this may +be, there is a place for the radial type in air-work for as long +as the internal combustion engine remains as a power plant. + + + +IV. THE ROTARY TYPE + +M. Laurent Seguin, the inventor of the Gnome rotary aero engine, +provided as great a stimulus to aviation as any that was given +anterior to the war period, and brought about a great advance in +mechanical flight, since these well-made engines gave a +high-power output for their weight, and were extremely smooth +in running. In the rotary design the crankshaft of the engine +is stationary, and the cylinders, crank case, and all their +adherent parts rotate; the working is thus exactly opposite in +principle to that of the radial type of aero engine, and the +advantage of the rotary lies in the considerable flywheel effect +produced by the revolving cylinders, with consequent evenness of +torque. Another advantage is that air-cooling, adopted in all +the Gnome engines, is rendered much more effective by the +rotation of the cylinders, though there is a tendency to +distortion through the leading side of each cylinder being more +efficiently cooled than the opposite side; advocates of other +types are prone to claim that the air resistance to the +revolving cylinders absorbs some 10 per cent of the power +developed by the rotary engine, but that has not prevented the +rotary from attaining to great popularity as a prime mover. + +There were, in the list of aero engines compiled in 1910, +five rotary engines included, all air-cooled. Three of these +were Gnome engines, and two of the make known as 'International.' +They ranged from 21.5 to 123 horse-power, the latter being rated +at only 1.8 lbs. weight per brake horse-power, and having +fourteen cylinders, 4.33 inches in diameter by 4.7 inches stroke. +By 1914 forty-three different sizes and types of rotary engine +were being constructed, and in 1913 five rotary type engines were +entered for the series of aeroplane engine trials held in +Germany. Minor defects ruled out four of these, and only the +German Bayerischer Motoren Flugzeugwerke completed the seven-hour +test prescribed for competing engines. Its large fuel +consumption barred this engine from the final trials, the +consumption being some 0.95 pints per horse-power per hour. The +consumption of lubricating oil, also was excessive, standing at +0.123 pint per horse-power per hour. The engine gave 37.5 +effective horse-power during its trial, and the loss due to air +resistance was 4.6 horse-power, about 11 per cent. The +accompanying drawing shows the construction of the engine, in +which the seven cylinders are arranged radially on the crank +case; the method of connecting the pistons to the crank pins can +be seen. The mixture is drawn through the crank chamber, and to +enter the cylinder it passes through the two automatic valves in +the crown of the piston; the exhaust valves are situated in the +tops of the cylinders, and are actuated by cams and push-rods. +Cooling of the cylinder is assisted by the radial rings, and the +diameter of these rings is increased round the hottest part of +the cylinder. When long flights are undertaken the advantage of +the light weight of this engine is more than counterbalanced by +its high fuel and lubricating oil consumption, but there are +other makes which are much better than this seven-cylinder German +in respect of this. + +Rotation of the cylinders in engines of this type is produced by +the side pressure of the pistons on the cylinder walls, and in +order to prevent this pressure from becoming abnormally large it +is necessary to keep the weight of the piston as low as possible, +as the pressure is produced by the tangential acceleration and +retardation of the piston. On the upward stroke the +circumferential velocity of the piston is rapidly increased, +which causes it to exert a considerable tangential pressure on +the side of the cylinder, and on the return stroke there is a +corresponding retarding effect due to the reduction of the +circumferential velocity of the piston. These side pressures +cause an appreciable increase in the temperatures of the +cylinders and pistons, which makes it necessary to keep the +power rating of the engines fairly low. + +Seguin designed his first Gnome rotary as a 34 horse-power +engine when run at a speed of 1,300 revolutions per minute. It +had five cylinders, and the weight was 3.9 lbs. per horse-power. +A seven-cylinder model soon displaced this first engine, and +this latter, with a total weight of 165 lbs., gave 61.5 +horse-power. The cylinders were machined out of solid nickel +chrome-steel ingots, and the machining was carried out so that +the cylinder walls were under 1/6 of an inch in thickness. The +pistons were cast-iron, fitted each with two rings, and the +automatic inlet valve to the cylinder was placed in the crown of +the piston. The connecting rods, of 'H' section, were of nickel +chrome-steel, and the large end of one rod, known as the +'master-rod' embraced the crank pin; on the end of this rod six +hollow steel pins were carried, and to these the remaining six +connecting-rods were attached. The crankshaft of the engine was +made of nickel chrome-steel, and was in two parts connected +together at the crank pin; these two parts, after the master-rod +had been placed in position and the other connecting rods had +been attached to it, were firmly secured. The steel crank case +was made in five parts, the two central ones holding the +cylinders in place, and on one side another of the five castings +formed a cam-box, to the outside of which was secured the +extension to which the air-screw was attached. On the other +side of the crank case another casting carried the thrust-box, +and the whole crank case, with its cylinders and gear, was +carried on the fixed crank shaft by means of four ball-bearings, +one of which also took the axial thrust of the air-screw. + +For these engines, castor oil is the lubricant usually adopted, +and it is pumped to the crankshaft by means of a gear-driven oil +pump; from this shaft the other parts of the engine are +lubricated by means of centrifugal force, and in actual practice +sufficient unburnt oil passes through the cylinders to lubricate +the exhaust valve, which partly accounts for the high rate of +consumption of lubricating oil. A very simple carburettor of +the float less, single-spray type was used, and the mixture was +passed along the hollow crankshaft to the interior of the crank +case, thence through the automatic inlet valves in the tops of +the pistons to the combustion chambers of the cylinders. +Ignition was by means of a high-tension magneto specially geared +to give the correct timing, and the working impulses occurred at +equal angular intervals of 102.85 degrees. The ignition was +timed so that the firing spark occurred when the cylinder was 26 +degrees before the position in which the piston was at the outer +end of its stroke, and this timing gave a maximum pressure in +the cylinder just after the piston had passed this position. + +By 1913, eight different sizes of the Gnome engine were being +constructed, ranging from 45 to 180 brake horse-power; four of +these were single-crank engines one having nine and the other +three having seven cylinders. The remaining four were +constructed with two cranks; three of them had fourteen +cylinders apiece, ranged in groups of seven, acting on the +cranks, and the one other had eighteen cylinders ranged in two +groups of nine, acting on its two cranks. Cylinders of the +two-crank engines are so arranged (in the fourteen-cylinder +type) that fourteen equal angular impulses occur during each +cycle; these engines are supported on bearings on both sides of +the engine, the air-screw being placed outside the front +support. In the eighteen-cylinder model the impulses occur at +each 40 degrees of angular rotation of the cylinders, securing +an extremely even rotation of the air-screw. + +In 1913 the Gnome Monosoupape engine was introduced, a model in +which the inlet valve to the cylinder was omitted, while the +piston was of the ordinary cast-iron type. A single exhaust +valve in the cylinder head was operated in a manner similar to +that on the previous Gnome engines, and the fact of this being +the only valve on the cylinder gave the engine its name. Each +cylinder contained ports at the bottom which communicated with +the crank chamber, and were overrun by the piston when this +was approaching the bottom end of its stroke. During the +working cycle of the engine the exhaust valve was opened early +to allow the exhaust gases to escape from the cylinder, so that +by the time the piston overran the ports at the bottom the +pressure within the cylinder was approximately equal to that in +the crank case, and practically no flow of gas took place in +either direction through the ports. The exhaust valve remained +open as usual during the succeeding up-stroke of the piston, and +the valve was held open until the piston had returned through +about one-third of its downward stroke, thus permitting fresh air +to enter the cylinder. The exhaust valve then closed, and the +downward motion of the piston, continuing, caused a partial +vacuum inside the cylinder; when the piston overran the ports, +the rich mixture from the crank case immediately entered. The +cylinder was then full of the mixture, and the next upward stroke +of the piston compressed the charge; upon ignition the working +cycle was repeated. The speed variation of this engine was +obtained by varying the extent and duration of the opening of the +exhaust valves, and was controlled by the pilot by hand-operated +levers acting on the valve tappet rollers. The weight per +horsepower of these engines was slightly less than that of the +two-valve type, while the lubrication of the gudgeon pin and +piston showed an improvement, so that a lower lubricating oil +consumption was obtained. The 100 horse-power Gnome Monosoupape +was built with nine cylinders, each 4.33 inches bore by 5.9 +inches stroke, and it developed its rated power at 1,200 +revolutions per minute. + +An engine of the rotary type, almost as well known as the Gnome, +is the Clerget, in which both cylinders and crank case are made +of steel, the former having the usual radial fins for cooling. +In this type the inlet and exhaust valves are both located in +the cylinder head, and mechanically operated by push-rods and +rockers. Pipes are carried from the crank case to the inlet +valve casings to convey the mixture to the cylinders, a +carburettor of the central needle type being used. The +carburetted mixture is taken into the crank case chamber in a +manner similar to that of the Gnome engine. Pistons of +aluminium alloy, with three cast-iron rings, are fitted, the top +ring being of the obturator type. The large end of one of the +nine connecting rods embraces the crank pin and the pressure is +taken on two ball-bearings housed in the end of the rod. This +carries eight pins, to which the other rods are attached, and the +main rod being rigid between the crank pin and piston pin +determines the position of the pistons. Hollow connecting-rods +are used, and the lubricating oil for the piston pins passes from +the crankshaft through the centres of the rods. Inlet and +exhaust valves can be set quite independently of one another--a +useful point, since the correct timing of the opening of these +valves is of importance. The inlet valve opens 4 degrees from +top centre and closes after the bottom dead centre of the piston; +the exhaust valve opens 68 degrees before the bottom centre and +closes 4 degrees after the top dead centre of the piston. The +magnetos are set to give the spark in the cylinder at 25 degrees +before the end of the compression stroke--two high-tension +magnetos are used: if desired, the second one can be adjusted to +give a later spark for assisting the starting of the engine. The +lubricating oil pump is of the valveless two-plunger type, so +geared that it runs at seven revolutions to 100 revolutions of +the engine; by counting the pulsations the speed of the engine +can be quickly calculated by multiplying the pulsations by 100 +and dividing by seven. In the 115 horse-power nine-cylinder +Clerget the cylinders are 4.7 bore with a 6.3 inches stroke, and +the rated power of the engine is obtained at 1,200 revolutions +per minute. The petrol consumption is 0.75 pint per horse-power +per hour. + +A third rotary aero engine, equally well known with the +foregoing two, is the Le Rhone, made in four different sizes +with power outputs of from 50 to 160 horse-power; the two +smaller sizes are single crank engines with seven and nine +cylinders respectively, and the larger sizes are of double-crank +design, being merely the two smaller sizes doubled--fourteen and +eighteen-cylinder engines. The inlet and exhaust valves are +located in the cylinder head, and both valves are mechanically +operated by one push-rod and rocker, radial pipes from crank +case to inlet valve casing taking the mixture to the cylinders. +The exhaust valves are placed on the leading, or air-screw side, +of the engine, in order to get the fullest possible cooling +effect. The rated power of each type of engine is obtained at +1,200 revolutions per minute, and for all four sizes the +cylinder bore is 4.13 inches, with a 5.5 inches piston stroke. +Thin cast-iron liners are shrunk into the steel cylinders in +order to reduce the amount of piston friction. Although the Le +Rhone engines are constructed practically throughout of steel, +the weight is only 2.9 lbs. per horse-power in the +eighteen-cylinder type. + +American enterprise in the construction of the rotary type is +perhaps best illustrated in the 'Gyro 'engine; this was first +constructed with inlet valves in the heads of the pistons, after +the Gnome pattern, the exhaust valves being in the heads of the +cylinders. The inlet valve in the crown of each piston was +mechanically operated in a very ingenious manner by the +oscillation of the connecting-rod. The Gyro-Duplex engine +superseded this original design, and a small cross-section +illustration of this is appended. It is constructed in seven and +nine-cylinder sizes, with a power range of from 50 to 100 +horse-power; with the largest size the low weight of 2.5 lbs.. +per horse-power is reached. The design is of considerable +interest to the internal combustion engineer, for it embodies a +piston valve for controlling auxiliary exhaust ports, which also +acts as the inlet valve to the cylinder. The piston uncovers the +auxiliary ports when it reaches the bottom of its stroke, and at +the end of the power stroke the piston is in such a position that +the exhaust can escape over the top of it. The exhaust valve in +the cylinder head is then opened by means of the push-rod and +rocker, and is held open until the piston has completed its +upward stroke and returned through more than half its subsequent +return stroke. When the exhaust valve closes, the cylinder has a +charge of fresh air, drawn in through the exhaust valve, and the +further motion of the piston causes a partial vacuum; by the time +the piston reaches bottom dead centre the piston-valve has moved +up to give communication between the cylinder and the crank case, +therefore the mixture is drawn into the cylinder. Both the +piston valve and exhaust valve are operated by cams formed on the +one casting, which rotates at seven-eighths engine speed for the +seven-cylinder type, and nine-tenths engine speed for the +nine-cylinder engines. Each of these cams has four or five +points respectively, to suit the number of cylinders. + +The steel cylinders are machined from solid forgings and +provided with webs for air-cooling as shown. Cast-iron pistons +are used, and are connected to the crankshaft in the same manner +as with the Gnome and Le Rhone engines. Petrol is sprayed into +the crank case by a small geared pump and the mixture is taken +from there to the piston valves by radial pipes. Two separate +pumps are used for lubrication, one forcing oil to the crank-pin +bearing and the other spraying the cylinders. + +Among other designs of rotary aero engines the E.J.C. is +noteworthy, in that the cylinders and crank case of this engine +rotate in opposite directions, and two air-screws are used, one +being attached to the end of the crankshaft, and the other to the +crank case. Another interesting type is the Burlat rotary, in +which both the cylinders and crankshaft rotate in the same +direction, the rotation of the crankshaft being twice that of the +cylinders as regards speed. This engine is arranged to work on +the four-stroke cycle with the crankshaft making four, and the +cylinders two, revolutions per cycle. + +It would appear that the rotary type of engine is capable of but +little more improvement--save for such devices as these of the +last two engines mentioned, there is little that Laurent Seguin +has not already done in the Gnome type. The limitation of the +rotary lies in its high fuel and lubricating oil consumption, +which renders it unsuited for long-distance aero work; it was, +in the war period, an admirable engine for such short runs as +might be involved in patrol work 'over the lines,' and for +similar purposes, but the watercooled Vee or even vertical, with +its much lower fuel consumption, was and is to be preferred for +distance work. The rotary air-cooled type has its uses, and for +them it will probably remain among the range of current types +for some time to come. Experience of matters aeronautical is +sufficient to show, however, that prophecy in any direction is +most unsafe. + + + +V. THE HORIZONTALLY-OPPOSED ENGINE + +Among the first internal combustion engines to be taken into use +with aircraft were those of the horizontally-opposed four-stroke +cycle type, and, in every case in which these engines were used, +their excellent balance and extremely even torque rendered them +ideal-until the tremendous increase in power requirements +rendered the type too long and bulky for placing in the fuselage +of an aeroplane. As power increased, there came a tendency +toward placing cylinders radially round a central crankshaft, +and, as in the case of the early Anzani, it may be said that the +radial engine grew out of the horizontal opposed piston type. +There were, in 1910--that is, in the early days of small power +units, ten different sizes of the horizontally opposed engine +listed for manufacture, but increase in power requirements +practically ruled out the type for air work. + +The Darracq firm were the leading makers of these engines in +1910; their smallest size was a 24 horsepower engine, with two +cylinders each of 5.1 inches bore by 4.7 inches stroke. This +engine developed its rated power at 1,500 revolutions per +minute, and worked out at a weight of 5 lbs. per horse-power. +With these engines the cranks are so placed that two regular +impulses are given to the crankshaft for each cycle of working, +an arrangement which permits of very even balancing of the +inertia forces of the engine. The Darracq firm also made a +four-cylindered horizontal opposed piston engine, in which two +revolutions were given to the crankshaft per revolution, at +equal angular intervals. + +The Dutheil-Chambers was another engine of this type, and had +the distinction of being the second largest constructed. At +1,000 revolutions per minute it developed 97 horse-power; its +four cylinders were each of 4.93 inches bore by 11.8 inches +stroke--an abnormally long stroke in comparison with the bore. +The weight--which owing to the build of the engine and its length +of stroke was bound to be rather high, actually amounted to 8.2 +lbs. per horse-power. Water cooling was adopted, and the engine +was, like the Darracq four-cylinder type, so arranged as to give +two impulses per revolution at equal angular intervals of +crankshaft rotation. + +One of the first engines of this type to be constructed in +England was the Alvaston, a water-cooled model which was made in +20, 30, and 50 brake horse-power sizes, the largest being a +four-cylinder engine. All three sizes were constructed to run +at 1,200 revolutions per minute. In this make the cylinders +were secured to the crank case by means of four long tie bolts +passing through bridge pieces arranged across the cylinder +heads, thus relieving the cylinder walls of all longitudinal +explosion stresses. These bridge pieces were formed from chrome +vanadium steel and milled to an 'H' section, and the bearings +for the valve-tappet were forged solid with them. Special +attention was given to the machining of the interiors of the +cylinders and the combustion heads, with the result that the +exceptionally high compression of 95 lbs. per square inch was +obtained, giving a very flexible engine. The cylinder heads +were completely water-jacketed, and copper water-jackets were +also fitted round the cylinders. The mechanically operated +valves were actuated by specially shaped cams, and were so +arranged that only two cams were required for the set of eight +valves. The inlet valves at both ends of the engine were +connected by a single feed-pipe to which the carburettor was +attached, the induction piping being arranged above the engine +in an easily accessible position. Auxiliary air ports were +provided in the cylinder walls so that the pistons overran them +at the end of their stroke. A single vertical shaft running in +ball-bearings operated the valves and water circulating pump, +being driven by spiral gearing from the crankshaft at half +speed. In addition to the excellent balance obtained with this +engine, the makers claimed with justice that the number of +working parts was reduced to an absolute minimum. + +In the two-cylinder Darracq, the steel cylinders were machined +from solid, and auxiliary exhaust ports, overrun by the piston +at the inner end of its stroke, were provided in the cylinder +walls, consisting of a circular row of drilled holes--this +arrangement was subsequently adopted on some of the Darracq +racing car engines. The water jackets were of copper, soldered +to the cylinder walls; both the inlet and exhaust valves were +located in the cylinder heads, being operated by rockers and +push-rods actuated by cams on the halftime shaft driven from one +end of the crankshaft. Ignition was by means of a high-tension +magneto, and long induction pipes connected the-ends of the +cylinders to the carburettor, the latter being placed underneath +the engine. Lubrication was effected by spraying oil into the +crank case by means of a pump, and a second pump circulated the +cooling water. + +Another good example of this type of engine was the Eole, which +had eight opposed pistons, each pair of which was actuated by a +common combustion chamber at the centre of the engine, two +crankshafts being placed at the outer ends of the engine. This +reversal of the ordinary arrangement had two advantages; it +simplified induction, and further obviated the need for cylinder +heads, since the explosion drove at two piston heads instead of +at one piston head and the top of the cylinder; against this, +however, the engine had to be constructed strongly enough to +withstand the longitudinal stresses due to the explosions, as +the cranks are placed on the outer ends and the cylinders and +crank-cases take the full force of each explosion. Each +crankshaft drove a separate air-screw. + +This pattern of engine was taken up by the Dutheil-Chambers firm +in the pioneer days of aircraft, when the firm in question +produced seven different sizes of horizontal engines. The +Demoiselle monoplane used by Santos-Dumont in 1909 was fitted +with a two-cylinder, horizontally-opposed Dutheil-Chambers +engine, which developed 25 brake horse-power at a speed of +1,100 revolutions per minute, the cylinders being of 5 inches +bore by 5.1 inches stroke, and the total weight of the engine +being some 120 lbs. The crankshafts of these engines were +usually fitted with steel flywheels in order to give a very even +torque, the wheels being specially constructed with wire spokes. +In all the Dutheil-Chambers engines water cooling was adopted, +and the cylinders were attached to the crank cases by means of +long bolts passing through the combustion heads. + +For their earliest machines, the Clement-Bayard firm constructed +horizontal engines of the opposed piston type. The best known of +these was the 30 horse-power size, which had cylinders of 4.7 +inches diameter by 5.1 inches stroke, and gave its rated power +at 1,200 revolutions per minute. In this engine the steel +cylinders were secured to the crank case by flanges, and +radiating ribs were formed around the barrel to assist the +air-cooling. Inlet and exhaust valves were actuated by +push-rods and rockers actuated from the second motion shaft +mounted above the crank case; this shaft also drove the +high-tension magneto with which the engine was fitted. A ring +of holes drilled round each cylinder constituted auxiliary ports +which the piston uncovered at the inner end of its stroke, and +these were of considerable assistance not only in expelling +exhaust gases, but also in moderating the temperature of the +cylinder and of the main exhaust valve fitted in the cylinder +head. A water-cooled Clement-Bayard horizontal engine was also +made, and in this the auxiliary exhaust ports were not embodied; +except in this particular, the engine was very similar to the +water-cooled Darracq. + +The American Ashmusen horizontal engine, developing 100 +horse-power, is probably the largest example of this type +constructed. It was made with six cylinders arranged on each +side of a common crank case, with long bolts passing through the +cylinder heads to assist in holding them down. The induction +piping and valve-operating gear were arranged below the engine, +and the half-speed shaft carried the air-screw. + +Messrs Palons and Beuse, Germans, constructed a light-weight, +air-cooled, horizontally-opposed engine, two-cylindered. In +this the cast-iron cylinders were made very thin, and were +secured to the crank case by bolts passing through lugs cast on +the outer ends of the cylinders; the crankshaft was made hollow, +and holes were drilled through the webs of the connecting-rods +in order to reduce the weight. The valves were fitted to the +cylinder heads, the inlet valves being of the automatic type, +while the exhaust valves were mechanically operated from the +cam-shaft by means of rockers and push-rods. Two carburettors +were fitted, to reduce the induction piping to a minimum; one +was attached to each combustion chamber, and ignition was by the +normal high-tension magneto driven from the halftime shaft. + +There was also a Nieuport two-cylinder air-cooled horizontal +engine, developing 35 horse-power when running at 1,300 +revolutions per minute, and being built at a weight of 5.1 lbs. +per horse-power. The cylinders were of 5.3 inches diameter by +5.9 inches stroke; the engine followed the lines of the Darracq +and Dutheil-Chambers pretty closely, and thus calls for no +special description. + +The French Kolb-Danvin engine of the horizontal type, first +constructed in 1905, was probably the first two-stroke cycle +engine designed to be applied to the propulsion of aircraft; it +never got beyond the experimental stage, although its trials +gave very good results. Stepped pistons were adopted, and the +charging pump at one end was used to scavenge the power cylinder +at the other ends of the engine, the transfer ports being formed +in the main casting. The openings of these ports were +controlled at both ends by the pistons, and the location of the +ports appears to have made it necessary to take the exhaust from +the bottom of one cylinder and from the top of the other. The +carburetted mixture was drawn into the scavenging cylinders, and +the usual deflectors were cast on the piston heads to assist in +the scavenging and to prevent the fresh gas from passing out of +the exhaust ports. + + + +VI. THE TWO-STROKE CYCLE ENGINE + +Although it has been little used for aircraft propulsion, the +possibilities of the two-stroke cycle engine render some study +of it desirable in this brief review of the various types of +internal combustion engine applicable both to aeroplanes and +airships. Theoretically the two-stroke cycle engine--or as it +is more commonly termed, the 'two-stroke,' is the ideal power +producer; the doubling of impulses per revolution of the +crankshaft should render it of very much more even torque than +the four-stroke cycle types, while, theoretically, there should +be a considerable saving of fuel, owing to the doubling of the +number of power strokes per total of piston strokes. In +practice, however, the inefficient scavenging of virtually every +two-stroke cycle engine produced nullifies or more than +nullifies its advantages over the four-stroke cycle engine; in +many types, too, there is a waste of fuel gases through the +exhaust ports, and much has yet to be done in the way of +experiment and resulting design before the two-stroke cycle +engine can be regarded as equally reliable, economical, and +powerful with its elder brother. + +The first commercially successful engine operating on the +two-stroke cycle was invented by Mr Dugald Clerk, who in 1881 +proved the design feasible. As is more or less generally +understood, the exhaust gases of this engine are discharged from +the cylinder during the time that the piston is passing the +inner dead centre, and the compression, combustion, and +expansion of the charge take place in similar manner to that of +the four-stroke cycle engine. The exhaust period is usually +controlled by the piston overrunning ports in the cylinder at +the end of its working stroke, these ports communicating direct +with the outer air--the complication of an exhaust valve is thus +obviated; immediately after the escape of the exhaust gases, +charging of the cylinder occurs, and the fresh gas may be +introduced either through a valve in the cylinder head or +through ports situated diametrically opposite to the exhaust +ports. The continuation of the outward stroke of the piston, +after the exhaust ports have been closed, compresses the charge +into the combustion chamber of the cylinder, and the ignition of +the mixture produces a recurrence of the working stroke. + +Thus, theoretically, is obtained the maximum of energy with the +minimum of expenditure; in practice, however, the scavenging of +the power cylinder, a matter of great importance in all internal +combustion engines, is often imperfect, owing to the opening of +the exhaust ports being of relatively short duration; clearing +the exhaust gases out of the cylinder is not fully accomplished, +and these gases mix with the fresh charge and detract from its +efficiency. Similarly, owing to the shorter space of time +allowed, the charging of the cylinder with the fresh mixture is +not so efficient as in the four-stroke cycle type; the fresh +charge is usually compressed slightly in a separate +chamber--crank case, independent cylinder, or charging pump, and +is delivered to the working cylinder during the beginning of the +return stroke of the piston, while in engines working on the +four-stroke cycle principle a complete stroke is devoted to the +expulsion of the waste gases of the exhaust, and another full +stroke to recharging the cylinder with fresh explosive mixture. + +Theoretically the two-stroke and the four-stroke cycle engines +possess exactly the same thermal efficiency, but actually this +is modified by a series of practical conditions which to some +extent tend to neutralise the very strong case in favour of the +two-stroke cycle engine. The specific capacity of the engine +operating on the two-stroke principle is theoretically twice +that of one operating on the four-stroke cycle, and +consequently, for equal power, the former should require only +about half the cylinder volume of the latter; and, owing to the +greater superficial area of the smaller cylinder, relatively, +the latter should be far more easily cooled than the larger +four-stroke cycle cylinder; thus it should be possible to get +higher compression pressures, which in turn should result in +great economy of working. Also the obtaining of a working +impulse in the cylinder for each revolution of the crankshaft +should give a great advantage in regularity of rotation--which +it undoubtedly does--and the elimination of the operating gear +for the valves, inlet and exhaust, should give greater +simplicity of design. + +In spite of all these theoretical--and some practical--advantages +the four-stroke cycle engine was universally adopted for aircraft +work; owing to the practical equality of the two principles of +operation, so far as thermal efficiency and friction losses are +concerned, there is no doubt that the simplicity of design (in +theory) and high power output to weight ratio (also in theory) +ought to have given the 'two-stroke' a place on the aeroplane. +But this engine has to be developed so as to overcome its +inherent drawbacks; better scavenging methods have yet to be +devised--for this is the principal drawback--before the +two-stroke can come to its own as a prime mover for aircraft. + +Mr Dugald Clerk's original two-stroke cycle engine is indicated +roughly, as regards principle, by the accompanying diagram, from +which it will be seen that the elimination of the ordinary inlet +and exhaust valves of the four-stroke type is more than +compensated by a separate cylinder which, having a piston worked +from the connecting-rod of the power cylinder, was used to +charging, drawing the mixture from the carburettor past the +valve in the top of the charging cylinder, and then forcing it +through the connecting pipe into the power cylinder. The inlet +valves both on the charging and the power cylinders are +automatic; when the power piston is near the bottom of its +stroke the piston in the charging cylinder is compressing the +carburetted air, so that as soon as the pressure within the +power cylinder is relieved by the exit of the burnt gases +through the exhaust ports the pressure in the charging cylinder +causes the valve in the head of the power cylinder to open, and +fresh mixture flows into the cylinder, replacing the exhaust +gases. After the piston has again covered the exhaust ports the +mixture begins to be compressed, thus automatically closing the +inlet valve. Ignition occurs near the end of the compression +stroke, and the working stroke immediately follows, thus giving +an impulse to the crankshaft on every down stroke of the piston. +If the scavenging of the cylinder were complete, and the cylinder +were to receive a full charge of fresh mixture for every stroke, +the same mean effective pressure as is obtained with four-stroke +cycle engines ought to be realised, and at an equal speed of +rotation this engine should give twice the power obtainable from +a four-stroke cycle engine of equal dimensions. This result was +not achieved, and, with the improvements in construction brought +about by experiment up to 1912, the output was found to be only +about fifty per cent more than that of a four-stroke cycle engine +of the same size, so that, when the charging cylinder is +included, this engine has a greater weight per horse-power, while +the lowest rate of fuel consumption recorded was 0.68 lb. per +horse-power per hour. + +In 1891 Mr Day invented a two-stroke cycle engine which used the +crank case as a scavenging chamber, and a very large number of +these engines have been built for industrial purposes. The +charge of carburetted air is drawn through a non-return valve +into the crank chamber during the upstroke of the piston, and +compressed to about 4 lbs. pressure per square inch on the +down stroke. When the piston approaches the bottom end of its +stroke the upper edge first overruns an exhaust port, and almost +immediately after uncovers an inlet port on the opposite side of +the cylinder and in communication with the crank chamber; the +entering charge, being under pressure, assists in expelling the +exhaust gases from the cylinder. On the next upstroke the +charge is compressed into the combustion space of the cylinder, +a further charge simultaneously entering the crank case to be +compressed after the ignition for the working stroke. To +prevent the incoming charge escaping through the exhaust ports +of the cylinder a deflector is formed on the top of the piston, +causing the fresh gas to travel in an upward direction, thus +avoiding as far as possible escape of the mixture to the +atmosphere. From experiments conducted in 1910 by Professor +Watson and Mr Fleming it was found that the proportion of fresh +gases which escaped unburnt through the exhaust ports diminished +with increase of speed; at 600 revolutions per minute about 36 +per cent of the fresh charge was lost; at 1,200 revolutions per +minute this was reduced to 20 per cent, and at 1,500 revolutions +it was still farther reduced to 6 per cent. + +So much for the early designs. With regard to engines of this +type specially constructed for use with aircraft, three designs +call for special mention. Messrs A. Gobe and H. Diard, Parisian +engineers, produced an eight-cylindered two-stroke cycle engine +of rotary design, the cylinders being co-axial. Each pair of +opposite pistons was secured together by a rigid connecting rod, +connected to a pin on a rotating crankshaft which was mounted +eccentrically to the axis of rotation of the cylinders. The +crankshaft carried a pinion gearing with an internally toothed +wheel on the transmission shaft which carried the air-screw. The +combustible mixture, emanating from a common supply pipe, was led +through conduits to the front ends of the cylinders, in which the +charges were compressed before being transferred to the working +spaces through ports in tubular extensions carried by the +pistons. These extensions had also exhaust ports, registering +with ports in the cylinder which communicated with the outer air, +and the extensions slid over depending cylinder heads attached to +the crank case by long studs. The pump charge was compressed in +one end of each cylinder, and the pump spaces each delivered +into their corresponding adjacent combustion spaces. The charges +entered the pump spaces during the suction period through +passages which communicated with a central stationary supply +passage at one end of the crank case, communication being cut off +when the inlet orifice to the passage passed out of register with +the port in the stationary member. The exhaust ports at the +outer end of the combustion space opened just before and closed a +little later than the air ports, and the incoming charge assisted +in expelling the exhaust gases in a manner similar to that of the +earlier types of two-stroke cycle engine; The accompanying rough +diagram assists in showing the working of this engine. + +Exhibited in the Paris Aero Exhibition of 1912, the Laviator +two-stroke cycle engine, six-cylindered, could be operated either +as a radial or as a rotary engine, all its pistons acting on a +single crank. Cylinder dimensions of this engine were 3.94 +inches bore by 5.12 inches stroke, and a power output of 50 +horse-power was obtained when working at a rate of 1,200 +revolutions per minute. Used as a radial engine, it developed +65 horse-power at the same rate of revolution, and, as the total +weight was about 198 lbs., the weight of about 3 lbs. per +horse-power was attained in radial use. Stepped pistons were +employed, the annular space between the smaller or power piston +and the walls of the larger cylinder being used as a charging +pump for the power cylinder situated 120 degrees in rear of it. +The charging cylinders were connected by short pipes to ports in +the crank case which communicated with the hollow crankshaft +through which the fresh gas was supplied, and once in each +revolution each port in the case registered with the port in the +hollow shaft. The mixture which then entered the charging +cylinder was transferred to the corresponding working +cylinder when the piston of that cylinder had reached the end of +its power stroke, and immediately before this the exhaust ports +diametrically opposite the inlet ports were uncovered; scavenging +was thus assisted in the usual way. The very desirable feature +of being entirely valveless was accomplished with this engine, +which is also noteworthy for exceedingly compact design. + +The Lamplough six-cylinder two-stroke cycle rotary, shown at the +Aero Exhibition at Olympia in 1911, had several innovations, +including a charging pump of rotary blower type. With the six +cylinders, six power impulses at regular intervals were given on +each rotation; otherwise, the cycle of operations was carried +out much as in other two-stroke cycle engines. The pump +supplied the mixture under slight pressure to an inlet port in +each cylinder, which was opened at the same time as the exhaust +port, the period of opening being controlled by the piston. The +rotary blower sucked the mixture from the carburettor and +delivered it to a passage communicating with the inlet ports in +the cylinder walls. A mechanically-operated exhaust valve was +placed in the centre of each cylinder head, and towards the end +of the working stroke this valve opened, allowing part of the +burnt gases to escape to the atmosphere; the remainder was +pushed out by the fresh mixture going in through the ports at +the bottom end of the cylinder. In practice, one or other of +the cylinders was always taking fresh mixture while working, +therefore the delivery from the pump was continuous and the +mixture had not to be stored under pressure. + +The piston of this engine was long enough to keep the ports +covered when it was at the top of the stroke, and a bottom ring +was provided to prevent the mixture from entering the crank +case. In addition to preventing leakage, this ring no doubt +prevented an excess of oil working up the piston into the +cylinder. As the cylinder fired with every revolution, the +valve gear was of the simplest construction, a fixed cam lifting +each valve as the cylinder came into position. The spring of +the exhaust valve was not placed round the stem in the usual +way, but at the end of a short lever, away from the heat of the +exhaust gases. The cylinders were of cast steel, the crank case +of aluminium, and ball-bearings were fitted to the crankshaft, +crank pins, and the rotary blower pump. Ignition was by means +of a high-tension magneto of the two-spark pattern, and with a +total weight of 300 lbs. the maximum output was 102 brake +horse-power, giving a weight of just under 3 lbs. per +horse-power. + +One of the most successful of the two-stroke cycle engines was +that designed by Mr G. F. Mort and constructed by the New +Engine Company. With four cylinders of 3.69 inches bore by 4.5 +inches stroke, and running at 1,250 revolutions per minute, this +engine developed 50 brake horse-power; the total weight of the +engine was 155 lbs., thus giving a weight of 3.1 lbs. per +horse-power. A scavenging pump of the rotary type was employed, +driven by means of gearing from the engine crankshaft, and in +order to reduce weight to a minimum the vanes were of aluminium. +This engine was tried on a biplane, and gave very satisfactory +results. + +American design yields two apparently successful two-stroke +cycle aero engines. A rotary called the Fredericson engine was +said to give an output of 70 brake horse-power with five +cylinders 4.5 inches diameter by 4.75 inches stroke, running +at 1,000 revolutions per minute. Another, the Roberts +two-stroke cycle engine, yielded 100 brake horse-power from six +cylinders of the stepped piston design; two carburettors, each +supplying three cylinders, were fitted to this engine. Ignition +was by means of the usual high-tension magneto, gear-driven from +the crankshaft, and the engine, which was water-cooled, was of +compact design. + +It may thus be seen that the two-stroke cycle type got as far as +actual experiment in air work, and that with considerable +success. So far, however, the greater reliability of the +four-stroke cycle has rendered it practically the only aircraft +engine, and the two-stroke has yet some way to travel before it +becomes a formidable competitor, in spite of its admitted +theoretical and questioned practical advantages. + + + +VII. ENGINES OF THE WAR PERIOD + +The principal engines of British, French, and American design +used in the war period and since are briefly described under the +four distinct types of aero engine; such notable examples as the +Rolls-Royce, Sunbeam, and Napier engines have been given special +mention, as they embodied--and still embody--all that is best in +aero engine practice. So far, however, little has been said +about the development of German aero engine design, apart from +the early Daimler and other pioneer makes. + +At the outbreak of hostilities in 1914, thanks to subsidies to +contractors and prizes to aircraft pilots, the German aeroplane +industry was in a comparatively flourishing condition. There +were about twenty-two establishments making different types of +heavier-thanair machines, monoplane and biplane, engined for the +most part with the four-cylinder Argus or the six-cylinder +Mercedes vertical type engines, each of these being of 100 +horse-power--it was not till war brought increasing demands on +aircraft that the limit of power began to rise. Contemporary +with the Argus and Mercedes were the Austro-Daimler, Benz, and +N.A.G., in vertical design, while as far as rotary types were +concerned there were two, the Oberursel and the Stahlhertz; of +these the former was by far the most promising, and it came to +virtual monopoly of the rotary-engined plane as soon as the war +demand began. It was practically a copy of the famous Gnome +rotary, and thus deserves little description. + +Germany, from the outbreak of war, practically, concentrated on +the development of the Mercedes engine; and it is noteworthy +that, with one exception, increase of power corresponding with +the increased demand for power was attained without increasing +the number of cylinders. The various models ranged between 75 +and 260 horse-power, the latter being the most recent production +of this type. The exception to the rule was the eight-cylinder +240 horse-power, which was replaced by the 260 horse-power +six-cylinder model, the latter being more reliable and but very +slightly heavier. Of the other engines, the 120 horsepower +Argus and the 160 and 225 horse-power Benz were the most used, +the Oberursel being very largely discarded after the Fokker +monoplane had had its day, and the N.A.G. and Austro-Daimler +Daimler also falling to comparative disuse. It may be said that +the development of the Mercedes engine contributed very largely +to such success as was achieved in the war period by German +aircraft, and, in developing the engine, the builders were +careful to make alterations in such a way as to effect the least +possible change in the design of aeroplane to which they were to +be fitted. Thus the engine base of the 175 horse-power model +coincided precisely with that of the 150 horse-power model, and +the 200 and 240 horse-power models retained the same base +dimensions. It was estimated, in 1918, that well over eighty +per cent of German aircraft was engined with the Mercedes type. + +In design and construction, there was nothing abnormal about the +Mercedes engine, the keynote throughout being extreme +reliability and such simplification of design as would permit of +mass production in different factories. Even before the war, +the long list of records set up by this engine formed practical +application of the wisdom of this policy; Bohn's flight of 24 +hours 10 minutes, accomplished on July 10th and 11th, 1914, +9is an instance of this--the flight was accomplished on an +Albatross biplane with a 75 horsepower Mercedes engine. The +radial type, instanced in other countries by the Salmson and +Anzani makes, was not developed in Germany; two radial engines +were made in that country before the war, but the Germans seemed +to lose faith in the type under war conditions, or it may have +been that insistence on standardisation ruled out all but the +proved examples of engine. + +Details of one of the middle sizes of Mercedes motor, the 176 +horse-power type, apply very generally to the whole range; this +size was in use up to and beyond the conclusion of hostilities, +and it may still be regarded as characteristic of modern (1920) +German practice. The engine is of the fixed vertical type, +has six cylinders in line, not off-set, and is water-cooled. +The cam shaft is carried in a special bronze casing, seated on +the immediate top of the cylinders, and a vertical shaft is +interposed between crankshaft and camshaft, the latter being +driven by bevel gearing. + +On this vertical connecting-shaft the water pump is located, +serving to steady the motion of the shaft. Extending immediately +below the camshaft is another vertical shaft, driven by bevel +gears from the crank-shaft, and terminating in a worm which +drives the multiple piston oil pumps. + +The cylinders are made from steel forgings, as are the valve +chamber elbows, which are machined all over and welded together. +A jacket of light steel is welded over the valve elbows and +attached to a flange on the cylinders, forming a water-cooling +space with a section of about 7/16 of an inch. The cylinder +bore is 5.5 inches, and the stroke 6.29 inches. The cylinders +are attached to the crank case by means of dogs and long through +bolts, which have shoulders near their lower ends and are bolted +to the lower half of the crank chamber. A very light and rigid +structure is thus obtained, and the method of construction won +the flattery of imitation by makers of other nationality. + +The cooling system for the cylinders is extremely efficient. +After leaving the water pump, the water enters the top of the +front cylinders and passes successively through each of the six +cylinders of the row; short tubes, welded to the tops of the +cylinders, serve as connecting links in the system. The Panhard +car engines for years were fitted with a similar cooling system, +and the White and Poppe lorry engines were also similarly +fitted; the system gives excellent cooling effect where it is +most needed, round the valve chambers and the cylinder heads. + +The pistons are built up from two pieces; a dropped forged steel +piston head, from which depend the piston pin bosses, is +combined with a cast-iron skirt, into which the steel head is +screwed. Four rings are fitted, three at the upper and one at +the lower end of the piston skirt, and two lubricating oil +grooves are cut in the skirt, in addition to the ring grooves. +Two small rivets retain the steel head on the piston skirt after +it has been screwed into position, and it is also welded at two +points. The coefficient of friction between the cast-iron and +steel is considerably less than that which would exist between +two steel parts, and there is less tendency for the skirt to +score the cylinder walls than would be the case if all steel were +used--so noticeable is this that many makers, after giving steel +pistons a trial, discarded them in favour of cast-iron; the Gnome +is an example of this, being originally fitted with a steel +piston carrying a brass ring, discarded in favour of a cast-iron +piston with a percentage of steel in the metal mixture. In the +Le Rhone engine the difficulty is overcome by a cast-iron liner +to the cylinders. + +The piston pin of the Mercedes is of chrome nickel steel, and is +retained in the piston by means of a set screw and cotter pin. +The connecting rods, of I section, are very short and rigid, +carrying floating bronze bushes which fit the piston pins at the +small end, and carrying an oil tube on each for conveying oil +from the crank pin to the piston pin. + +The crankshaft is of chrome nickel steel, carried on seven +bearings. Holes are drilled through each of the crank pins and +main bearings, for half the diameter of the shaft, and these are +plugged with pressed brass studs. Small holes, drilled through +the crank cheeks, serve to convey lubricant from the main +bearings to the crank pins. The propeller thrust is taken by a +simple ball thrust bearing at the propeller end of the +crankshaft, this thrust bearing being seated in a steel retainer +which is clamped between the two halves of the crank case. At +the forward end of the crankshaft there is mounted a master +bevel gear on six splines; this bevel floats on the splines +against a ball thrust bearing, and, in turn, the thrust is taken +by the crank case cover. A stuffing box prevents the loss of +lubricant out of the front end of the crank chamber, and an oil +thrower ring serves a similar purpose at the propeller end of the +crank chamber. + +With a motor speed of 1,450 r.p.m., the vertical shaft at the +forward end of the motor turns at 2,175 r.p.m., this being the +speed of the two magnetos and the water pump. The lower +vertical shaft bevel gear and the magneto driving gear are made +integral with the vertical driving shaft, which is carried in +plain bearings in an aluminium housing. This housing is clamped +to the upper half of the crank case by means of three studs. +The cam-shaft carries eighteen cams, these being the inlet and +exhaust cams, and a set of half compression cams which are +formed with the exhaust cams and are put into action when +required by means of a lever at the forward end of the +cam-shaft. The cam-shaft is hollow, and serves as a channel for +the conveyance of lubricating oil to each of the camshaft +bearings. At the forward end of this shaft there is also +mounted an air pump for maintaining pressure on the fuel supply +tank, and a bevel gear tachometer drive. + +Lubrication of the engine is carried out by a full pressure +system. The oil is pumped through a single manifold, with seven +branches to the crankshaft main bearings, and then in turn +through the hollow crankshaft to the connecting-rod big ends and +thence through small tubes, already noted, to the small end +bearings. The oil pump has four pistons and two double valves +driven from a single eccentric shaft on which are mounted four +eccentrics. The pump is continuously submerged in oil; in order +to avoid great variations in pressure in the oil lines there is +a piston operated pressure regulator, cut in between the pump +and the oil lines. The two small pistons of the pump take fresh +oil from a tank located in the fuselage of the machine; one of +these delivers oil to the cam shaft, and one delivers to the +crankshaft; this fresh oil mixes with the used oil, returns to +the base, and back to the main large oil pump cylinders. By +means of these small pump pistons a constant quantity of oil is +kept in the motor, and the oil is continually being freshened by +means of the new oil coming in. All the oil pipes are very +securely fastened to the lower half of the crank case, and some +cooling of the oil is effected by air passing through channels +cast in the crank case on its way to the carburettor. + +A light steel manifold serves to connect the exhaust ports of +the cylinders to the main exhaust pipe, which is inclined about +25 degrees from vertical and is arranged to give on to the +atmosphere just over the top of the upper wing of the aeroplane. + +As regards carburation, an automatic air valve surrounds the +throat of the carburettor, maintaining normal composition of +mixture. A small jet is fitted for starting and running without +load. The channels cast in the crank chamber, already alluded +to in connection with oil-cooling, serve to warm the air before +it reaches the carburettor, of which the body is water-jacketed. + +Ignition of the engine is by means of two Bosch ZH6 magnetos, +driven at a speed of 2,175 revolutions per minute when the engine +is running at its normal speed of 1,450 revolutions. The maximum +advance of spark is 12 mm., or 32 degrees before the top dead +centre, and the firing order of the cylinders is 1,5,3,6,2,4. + +The radiator fitted to this engine, together with the +water-jackets, has a capacity of 25 litres of water, it is +rectangular in shape, and is normally tilted at an angle of 30 +degrees from vertical. Its weight is 26 kg., and it offers but +slight head resistance in flight. + +The radial type of engine, neglected altogether in Germany, was +brought to a very high state of perfection at the end of the +War period by British makers. Two makes, the Cosmos Engineering +Company's 'Jupiter' and 'Lucifer,' and the A.B.C. 'Wasp II' and +'Dragon Fly 1A' require special mention for their light weight +and reliability on trials. + +The Cosmos 'Jupiter' was--for it is no longer being made--a 450 +horse-power nine-cylinder radial engine, air-cooled, with the +cylinders set in one single row; it was made both geared to +reduce the propeller revolutions relatively to the crankshaft +revolutions, and ungeared; the normal power of the geared type +was 450 horse-power, and the total weight of the engine, +including carburettors, magnetos, etc., was only 757 lbs.; the +engine speed was 1,850 revolutions per minute, and the propeller +revolutions were reduced by the gearing to 1,200. Fitted to a +'Bristol Badger' aeroplane, the total weight was 2,800 lbs., +including pilot, passenger, two machine-guns, and full military +load; at 7,000 feet the registered speed, with corrections for +density, was 137 miles per hour; in climbing, the first 2,000 +feet was accomplished in 1 minute 4 seconds; 4,000 feet was +reached in 2 minutes 10 seconds; 6,000 feet was reached in 3 +minutes 33 seconds, and 7,000 feet in 4 minutes 15 seconds. +It was intended to modify the plane design and fit a new +propeller, in order to attain even better results, but, if +trials were made with these modifications, the results are not +obtainable. + +The Cosmos 'Lucifer' was a three-cylinder radial type engine of +100 horse-power, inverted Y design, made on the simplest possible +principles with a view to quantity production and extreme +reliability. The rated 100 horse-power was attained at 1,600 +revolutions per minute, and the cylinder dimensions were 5.75 +bore by 6.25 inches stroke. The cylinders were of aluminium and +steel mixture, with aluminium heads; overhead valves, operated by +push rods on the front side of the cylinders, were fitted, and a +simple reducing gear ran them at half engine speed. The crank +case was a circular aluminium casting, the engine being attached +to the fuselage of the aeroplane by a circular flange situated at +the back of the case; propeller shaft and crankshaft were +integral. Dual ignition was provided, the generator and +distributors being driven off the back end of the engine and the +distributors being easily accessible. Lubrication was by means +of two pumps, one scavenging and one suction, oil being fed under +pressure from the crankshaft. A single carburettor fed all three +cylinders, the branch pipe from the carburettor to the circular +ring being provided with an exhaust heater. The total weight of +the engine, 'all on,' was 280 lbs. + +The A.B.C. 'Wasp II,' made by Walton Motors, Limited, is a +seven-cylinder radial, air-cooled engine, the cylinders having a +bore of 4.75 inches and stroke 6.25 inches. The normal brake +horse-power at 1,650 revolutions is 160, and the maximum 200 at +a speed of 1,850 revolutions per minute. Lubrication is by +means of two rotary pumps, one feeding through the hollow +crankshaft to the crank pin, giving centrifugal feed to big end +and thence splash oiling, and one feeding to the nose of the +engine, dropping on to the cams and forming a permanent sump for +the gears on the bottom of the engine nose. Two carburettors +are fitted, and two two-spark magnetos, running at one and +three-quarters engine speed. The total weight of this engine is +350 lbs., or 1.75 lbs. per horse-power. Oil consumption at 1,850 +revolutions is .03 pints per horse-power per hour, and petrol +consumption is .56 pints per horsepower per hour. The engine +thus shows as very economical in consumption, as well as very +light in weight. + +The A.B.C. 'Dragon Fly 1A 'is a nine-cylinder radial engine +having one overhead inlet and two overhead exhaust valves per +cylinder. The cylinder dimensions are 5.5 inches bore by 6.5 +inches stroke, and the normal rate of speed, 1,650 revolutions +per minute, gives 340 horse-power. The oiling is by means of +two pumps, the system being practically identical with that of +the 'Wasp II.' Oil consumption is .021 pints per brake +horse-power per hour, and petrol consumption .56 pints--the +same as that of the 'Wasp II.' The weight of the complete +engine, including propeller boss, is 600 lbs., or 1,765 lbs. +per horse-power. + +These A.B.C. radials have proved highly satisfactory on tests, +and their extreme simplicity of design and reliability commend +them as engineering products and at the same time demonstrate +the value, for aero work, of the air-cooled radial +design--when this latter is accompanied by sound workmanship. +These and the Cosmos engines represent the minimum of weight per +horse-power yet attained, together with a practicable degree of +reliability, in radial and probably any aero engine design. + + + + APPENDIX A + +GENERAL MENSIER'S REPORT ON THE TRIALS OF CLEMENT ADER'S AVION. + + Paris, October 21, 1897. + +Report on the trials of M. Clement Ader's aviation apparatus. + +M. Ader having notified the Minister of War by letter, July 21, +1897, that the Apparatus of Aviation which he had agreed to +build under the conditions set forth in the convention of July +24th, 1894, was ready, and therefore requesting that trials be +undertaken before a Committee appointed for this purpose as per +the decision of August 4th, the Committee was appointed as +follows:-- + +Division General Mensier, Chairman; Division General Delambre, +Inspector General of the Permanent Works of Coast Defence, +Member of the Technical Committee of the Engineering Corps; +Colonel Laussedat, Director of the Conservatoire des Arts et +Metiers; Sarrau, Member of the Institute, Professor of +Mechanical Engineering at the Polytechnic School; Leaute, Member +of the Institute, Professor of Mechanical Engineering at the +Polytechnique School. + +Colonel Laussedat gave notice at once that his health and work +as Director of the Conservatoire des Arts et Metiers did not +permit him to be a member of the Committee; the Minister +therefore accepted his resignation on September 24th, and +decided not to replace him. + +Later on, however, on the request of the Chairman of the +Committee, the Minister appointed a new member General Grillon, +commanding the Engineer Corps of the Military Government of +Paris. + +To carry on the trials which were to take place at the camp of +Satory, the Minister ordered the Governor of the Military Forces +of Paris to requisition from the Engineer Corps, on the request +of the Chairman of the Committee, the men necessary to prepare +the grounds at Satory. + +After an inspection made on the 16th an aerodrome was chosen. +M. Ader's idea was to have it of circular shape with a width of +40 metres and an average diameter of 450 metres. The preliminary +work, laying out the grounds, interior and exterior +circumference, etc., was finished at the end of August; the work +of smoothing off the grounds began September 1st with forty-five +men and two rollers, and was finished on the day of the first +tests, October 12th. + +The first meeting of the Committee was held August 18th in M. +Ader's workshop; the object being to demonstrate the machine to +the Committee and give all the information possible on the tests +that were to be held. After a careful examination and after +having heard all the explanations by the inventor which were +deemed useful and necessary, the Committee decided that the +apparatus seemed to be built with a perfect understanding of the +purpose to be fulfilled as far as one could judge from a study +of the apparatus at rest; they therefore authorised M. Ader to +take the machine apart and carry it to the camp at Satory so as +to proceed with the trials. + +By letter of August 19th the Chairman made report to the Minister +of the findings of the Committee. + +The work on the grounds having taken longer than was anticipated, +the Chairman took advantage of this delay to call the Committee +together for a second meeting, during which M. Ader was to run +the two propulsive screws situated at the forward end of the +apparatus. + +The meeting was held October 2nd. It gave the Committee an +opportunity to appreciate the motive power in all its details; +firebox, boiler, engine, under perfect control, absolute +condensation, automatic fuel and feed of the liquid to be +vaporised, automatic lubrication and scavenging; everything, in +a word, seemed well designed and executed. + +The weights in comparison with the power of the engine realised +a considerable advance over anything made to date, since the two +engines weighed together realised 42 kg., the firebox and boiler +60 kg., the condenser 15 kg., or a total of 117 kg. for +approximately 40 horse-power or a little less than 3 kg. per +horse-power. + +One of the members summed up the general opinion by saying: +'Whatever may be the result from an aviation point of view, a +result which could not be foreseen for the moment, it was +nevertheless proven that from a mechanical point of view M. +Ader's apparatus was of the greatest interest and real +ingeniosity. He expressed a hope that in any case the machine +would not be lost to science.' + +The second experiment in the workshop was made in the presence +of the Chairman, the purpose being to demonstrate that the +wings, having a spread of 17 metres, were sufficiently strong +to support the weight of the apparatus. With this object in +view, 14 sliding supports were placed under each one of these, +representing imperfectly the manner in which the wings would +support the machine in the air; by gradually raising the +supports with the slides, the wheels on which the machine rested +were lifted from the ground. It was evident at that time that +the members composing the skeleton of the wings supported the +apparatus, and it was quite evident that when the wings were +supported by the air on every point of their surface, the stress +would be better equalised than when resting on a few supports, +and therefore the resistance to breakage would be considerably +greater. + +After this last test, the work on the ground being practically +finished, the machine was transported to Satory, assembled and +again made ready for trial. + +At first M. Ader was to manoeuvre the machine on the ground at +a moderate speed, then increase this until it was possible to +judge whether there was a tendency for the machine to rise; and +it was only after M. Ader had acquired sufficient practice that +a meeting of the Committee was to be called to be present at the +first part of the trials; namely, volutions of the apparatus on +the ground. + +The first test took place on Tuesday, October 12th, in the +presence of the Chairman of the Committee. It had rained a good +deal during the night and the clay track would have offered +considerable resistance to the rolling of the machine; +furthermore, a moderate wind was blowing from the south-west, +too strong during the early part of the afternoon to allow of +any trials. + +Toward sunset, however, the wind having weakened, M. Ader +decided to make his first trial; the machine was taken out of +its hangar, the wings were mounted and steam raised. M. Ader +in his seat had, on each side of him, one man to the right and +one to the left, whose duty was to rectify the direction of the +apparatus in the event that the action of the rear wheel as a +rudder would not be sufficient to hold the machine in a straight +course. + +At 5.25 p.m. the machine was started, at first slowly and then +at an increased speed; after 250 or 300 metres, the two men who +were being dragged by the apparatus were exhausted and forced to +fall flat on the ground in order to allow the wings to pass over +them, and the trip around the track was completed, a total of +1,400 metres, without incident, at a fair speed, which could be +estimated to be from 300 to 400 metres per minute. +Notwithstanding M. Ader's inexperience, this being the first +time that he had run his apparatus, he followed approximately +the chalk line which marked the centre of the track and he +stopped at the exact point from which he started. + +The marks of the wheels on the ground, which was rather soft, +did not show up very much, and it was clear that a part of the +weight of the apparatus had been supported by the wings, though +the speed was only about one-third of what the machine could do +had M. Ader used all its motive power; he was running at a +pressure of from 3 to 4 atmospheres, when he could have used 10 +to 12. + +This first trial, so fortunately accomplished, was of great +importance; it was the first time that a comparatively heavy +vehicle (nearly 400 kg., including the weight of the operator, +fuel, and water) had been set in motion by a tractive apparatus, +using the air solely as a propelling medium. The favourable +report turned in by the Committee after the meeting of October +2nd was found justified by the results demonstrated on the +grounds, and the first problem of aviation, namely, the creation +of efficient motive power, could be considered as solved, since +the propulsion of the apparatus in the air would be a great deal +easier than the traction on the ground, provided that the second +part of the problem, the sustaining of the machine in the air, +would be realised. + +The next day, Wednesday the 13th, no further trials were made +on account of the rain and wind. + +On Thursday the 14th the Chairman requested that General +Grillon, who had just been appointed a member of the Committee, +accompany him so as to have a second witness. + +The weather was fine, but a fairly strong, gusty wind was +blowing from the south. M. Ader explained to the two members +of the Committee the danger of these gusts, since at two points +of the circumference the wind would strike him sideways. The +wind was blowing in the direction A B, the apparatus starting +from C, and running in the direction shown by the arrow. The +first dangerous spot would be at B. The apparatus had been kept +in readiness in the event of the wind dying down. Toward sunset +the wind seemed to die down, as it had done on the evening of +the 12th. M. Ader hesitated, which, unfortunately, further +events only justified, but decided to make a new trial. + +At the start, which took place at 5.15 p.m., the apparatus, +having the wind in the rear, seemed to run at a fairly regular +speed; it was, nevertheless, easy to note from the marks of the +wheels on the ground that the rear part of the apparatus had been +lifted and that the rear wheel, being the rudder, had not been in +constant contact with the ground. When the machine came to the +neighbourhood of B, the two members of the Committee saw the +machine swerve suddenly out of the track in a semicircle, lean +over to the right and finally stop. They immediately proceeded +to the point where the accident had taken place and endeavoured +to find an explanation for the same. The Chairman finally +decided as follows: + +M. Ader was the victim of a gust of wind which he had feared as +he explained before starting out; feeling himself thrown out of +his course, he tried to use the rudder energetically, but at that +time the rear wheel was not in contact with the ground, and +therefore did not perform its function; the canvas rudder, which +had as its purpose the manoeuvring of the machine in the air, did +not have sufficient action on the ground. It would have been +possible without any doubt to react by using the propellers at +unequal speed, but M. Ader, being still inexperienced, had not +thought of this. Furthermore, he was thrown out of his course so +quickly that he decided, in order to avoid a more serious +accident, to stop both engines. This sudden stop produced the +half-circle already described and the fall of the machine on its +side. + +The damage to the machine was serious; consisting at first sight +of the rupture of both propellers, the rear left wheel and the +bending of the left wing tip. It will only be possible to +determine after the machine is taken apart whether the engine, +and more particularly the organs of transmission, have been put +out of line. + +Whatever the damage may be, though comparatively easy to repair, +it will take a certain amount of time, and taking into +consideration the time of year it is evident that the tests will +have to be adjourned for the present. + +As has been said in the above report, the tests, though +prematurely interrupted, have shown results of great importance, +and though the final results are hard to foresee, it would seem +advisable to continue the trials. By waiting for the return of +spring there will be plenty of time to finish the tests and it +will not be necessary to rush matters, which was a partial cause +of the accident. The Chairman of the Committee personally has +but one hope, and that is that a decision be reached accordingly. + + Division General, + Chairman of the Committee, + Mensier. + +Boulogne-sur-Seine, October 21st, 1897. + + Annex to the Report of October 21st. + +General Grillon, who was present at the trials of the 14th, and +who saw the report relative to what happened during that day, +made the following observations in writing, which are reproduced +herewith in quotation marks. The Chairman of the Committee does +not agree with General Grillon and he answers theseobservations +paragraph by paragraph. + +1. 'If the rear wheel (there is only one of these) left but +intermittent tracks on the ground, does that prove that the +machine has a tendency to rise when running at a certain speed?' + +Answer.--This does not prove anything in any way, and I was very +careful not to mention this in my report, this point being +exactly what was needed and that was not demonstrated during the +two tests made on the grounds. + +'Does not this unequal pressure of the two pair of wheels on the +ground show that the centre of gravity of the apparatus is +placed too far forward and that under the impulse of the +propellers the machine has a tendency to tilt forward, due to +the resistance of the air?' + +Answer.--The tendency of the apparatus to rise from the rear +when it was running with the wind seemed to be brought about by +the effects of the wind on the huge wings, having a spread of 17 +metres, and I believe that when the machine would have faced the +wind the front wheels would have been lifted. + +During the trials of October 12th, when a complete circuit of +the track was accomplished without incidents, as I and Lieut. +Binet witnessed, there was practically no wind. I was therefore +unable to verify whether during this circuit the two front +wheels or the rear wheel were in constant contact with the +ground, because when the trial was over it was dark (it was +5.30) and the next day it was impossible to see anything because +it had rained during the night and during Wednesday morning. +But what would prove that the rear wheel was in contact with the +ground at all times is the fact that M. Ader, though +inexperienced, did not swerve from the circular track, which +would prove that he steered pretty well with his rear +wheel--this he could not have done if he had been in the air. + +In the tests of the 12th, the speed was at least as great as on +the 14th. + +2. 'It would seem to me that if M. Ader thought that his rear +wheels were off the ground he should have used his canvas rudder +in order to regain his proper course; this was the best way of +causing the machine to rotate, since it would have given an +angular motion to the front axle.' + +Answer.--I state in my report that the canvas rudder whose +object was the manoeuvre of the apparatus in the air could have +no effect on the apparatus on the ground, and to convince +oneself of this point it is only necessary to consider the small +surface of this canvas rudder compared with the mass to be +handled on the ground, a weight of approximately 400 kg. +According to my idea, and as I have stated in my report, M. Ader +should have steered by increasing the speed on one of his +propellers and slowing down the other. He admitted afterward +that this remark was well founded, but that he did not have time +to think of it owing to the suddenness of the accident. + +3. 'When the apparatus fell on its side it was under the sole +influence of the wind, since M. Ader had stopped the machine. +Have we not a result here which will always be the same when the +machine comes to the ground, since the engines will always have +to be stopped or slowed down when coming to the ground? Here +seems to be a bad defect of the apparatus under trial.' + +Answer.--I believe that the apparatus fell on its side after +coming to a stop, not on account of the wind, but because the +semicircle described was on rough ground and one of the wheels +had collapsed. + Mensier. +October 27th, 1897. + + + + APPENDIX B + +Specification and Claims of Wright Patent, No. 821393. +Filed March 23rd, 1903. Issued May 22nd, 1906. Expires May +22nd, 1923. + +To all whom it may concern. + +Be it known that we, Orville Wright and Wilbur Wright, citizens +of the United States, residing in the city of Dayton, county of +Montgomery, and State of Ohio, have invented certain new and +useful Improvements in Flying Machines, of which the following +is a specification. + +Our invention relates to that class of flying-machines in which +the weight is sustained by the reactions resulting when one or +more aeroplanes are moved through the air edgewise at a small +angle of incidence, either by the application of mechanical +power or by the utilisation of the force of gravity. + +The objects of our invention are to provide means for +maintaining or restoring the equilibrium or lateral balance of +the apparatus, to provide means for guiding the machine both +vertically and horizontally, and to provide a structure +combining lightness, strength, convenience of construction and +certain other advantages which will hereinafter appear. + +To these ends our invention consists in certain novel features, +which we will now proceed to describe and will then particularly +point out in the claims. In the accompanying drawings, Figure I +1 is a perspective view of an apparatus embodying our invention +in one form. Fig. 2 is a plan view of the same, partly in +horizontal section and partly broken away. Fig. 3 is a side +elevation, and Figs. 4 and 5 are detail views, of one form of +flexible joint for connecting the upright standards with the +aeroplanes. + +In flying machines of the character to which this invention +relates the apparatus is supported in the air by reason of the +contact between the air and the under surface of one or more +aeroplanes, the contact surface being presented at a small angle +of incidence to the air. The relative movements of the air and +aeroplane may be derived from the motion of the air in the form +of wind blowing in the direction opposite to that in which the +apparatus is travelling or by a combined downward and forward +movement of the machine, as in starting from an elevated +position or by combination of these two things, and in either +case the operation is that of a soaring-machine, while power +applied to the machine to propel it positively forward will +cause the air to support the machine in a similar manner. In +either case owing to the varying conditions to be met there are +numerous disturbing forces which tend to shift the machine from +the position which it should occupy to obtain the desired +results. It is the chief object of our invention to provide +means for remedying this difficulty, and we will now proceed to +describe the construction by means of which these results are +accomplished. + +In the accompanying drawing we have shown an apparatus embodying +our invention in one form. In this illustrative embodiment the +machine is shown as comprising two parallel superposed +aeroplanes, 1 and 2, may be embodied in a structure having a +single aeroplane. Each aeroplane is of considerably greater width +from side to side than from front to rear. The four corners of +the upper aeroplane are indicated by the reference letters a, b, +c, and d, while the corresponding corners of the lower aeroplane +2 are indicated by the reference letters e, f, g, and h. The +marginal lines ab and ef indicate the front edges of the +aeroplanes, the lateral margins of the upper aeroplane are +indicated, respectively, by the lines ad and bc, the lateral +margins of the lower aeroplane are indicated, respectively, by +the lines eh and fg, while the rear margins of the upper and +lower aeroplanes are indicated, respectively, by the lines cd and +gh. + +Before proceeding to a description of the fundamental theory of +operation of the structure we will first describe the preferred +mode of constructing the aeroplanes and those portions of the +structure which serve to connect the two aeroplanes. + +Each aeroplane is formed by stretching cloth or other suitable +fabric over a frame composed of two parallel transverse spars 3, +extending from side to side of the machine, their ends being +connected by bows 4 extending from front to rear of the machine. +The front and rear spars 3 of each aeroplane are connected by a +series of parallel ribs 5, which preferably extend somewhat +beyond the rear spar, as shown. These spars, bows, and ribs are +preferably constructed of wood having the necessary strength, +combined with lightness and flexibility. Upon this framework +the cloth which forms the supporting surface of the aeroplane is +secured, the frame being enclosed in the cloth. The cloth for +each aeroplane previous to its attachment to its frame is cut on +the bias and made up into a single piece approximately the size +and shape of the aeroplane, having the threads of the fabric +arranged diagonally to the transverse spars and longitudinal +ribs, as indicated at 6 in Fig. 2. Thus the diagonal threads of +the cloth form truss systems with the spars and ribs, the threads +constituting the diagonal members. A hem is formed at the rear +edge of the cloth to receive a wire 7, which is connected to the +ends of the rear spar and supported by the rearwardly-extending +ends of the longitudinal ribs 5, thus forming a +rearwardly-extending flap or portion of the aeroplane. This +construction of the aeroplane gives a surface which has very +great strength to withstand lateral and longitudinal strains, at +the same time being capable of being bent or twisted in the +manner hereinafter described. + +When two aeroplanes are employed, as in the construction +illustrated, they are connected together by upright standards 8. +These standards are substantially rigid, being preferably +constructed of wood and of equal length, equally spaced along +the front and rear edges of the aeroplane, to which they are +connected at their top and bottom ends by hinged joints or +universal joints of any suitable description. We have shown one +form of connection which may be used for this purpose in Figs. 4 +and 5 of the drawings. In this construction each end of the +standard 8 has secured to it an eye 9 which engages with a hook +10, secured to a bracket plate 11, which latter plate is in +turn fastened to the spar 3. Diagonal braces or stay-wires 12 +extend from each end of each standard to the opposite ends of +the adjacent standards, and as a convenient mode of attaching +these parts I have shown a hook 13 made integral with the hook +10 to receive the end of one of the stay-wires, the other +stay-wire being mounted on the hook 10. The hook 13 is shown +as bent down to retain the stay-wire in connection to it, while +the hook 10 is shown as provided with a pin 14 to hold the +staywire 12 and eye 9 in position thereon. It will be seen that +this construction forms a truss system which gives the whole +machine great transverse rigidity and strength, while at the +same time the jointed connections of the parts permit the +aeroplanes to be bent or twisted in the manner which we will now +proceed to describe. + +15 indicates a rope or other flexible connection extending +lengthwise of the front of the machine above the lower +aeroplane, passing under pulleys or other suitable guides 16 at +the front corners e and f of the lower aeroplane, and extending +thence upward and rearward to the upper rear corners c and d, of +the upper aeroplane, where they are attached, as indicated at +17. To the central portion of the rope there is connected a +laterally-movable cradle 18, which forms a means for moving the +rope lengthwise in one direction or the other, the cradle being +movable toward either side of the machine. We have devised this +cradle as a convenient means for operating the rope 15, and the +machine is intended to be generally used with the operator lying +face downward on the lower aeroplane, with his head to the +front, so that the operator's body rests on the cradle, and the +cradle can be moved laterally by the movements of the operator's +body. It will be understood, however, that the rope 15 may be +manipulated in any suitable manner. + +19 indicates a second rope extending transversely of the +machine along the rear edge of the body portion of the lower +aeroplane, passing under suitable pulleys or guides 20 at the +rear corners g and h of the lower aeroplane and extending thence +diagonally upward to the front corners a and b of the upper +aeroplane, where its ends are secured in any suitable manner, as +indicated at 21. + +Considering the structure so far as we have now described it, +and assuming that the cradle 18 be moved to the right in Figs. +1 and 2, as indicated by the arrows applied to the cradle in +Fig. 1 and by the dotted lines in Fig. 2, it will be seen that +that portion of the rope 15 passing under the guide pulley at +the corner e and secured to the corner d will be under tension, +while slack is paid out throughout the other side or half of the +rope 15. The part of the rope 15 under tension exercises a +downward pull upon the rear upper corner d of the structure and +an upward pull upon the front lower corner e, as indicated by +the arrows. This causes the corner d to move downward and the +corner e to move upward. As the corner e moves upward it +carries the corner a upward with it, since the intermediate +standard 8 is substantially rigid and maintains an equal +distance between the corners a and e at all times. Similarly, +the standard 8, connecting the corners d and h, causes the +corner h to move downward in unison with the corner d. Since +the corner a thus moves upward and the corner h moves downward, +that portion of the rope 19 connected to the corner a will be +pulled upward through the pulley 20 at the corner h, and the +pull thus exerted on the rope 19 will pull the corner b on the +other wise of the machine downward and at the same time pull the +corner g at said other side of the machine upward. This results +in a downward movement of the corner b and an upward movement of +the corner c. Thus it results from a lateral movement of the +cradle 18 to the right in Fig. 1 that the lateral margins ad +and eh at one side of the machine are moved from their normal +positions in which they lie in the normal planes of their +respective aeroplanes, into angular relations with said normal +planes, each lateral margin on this side of the machine being +raised above said normal plane at its forward end and depressed +below said normal plane at its rear end, said lateral margins +being thus inclined upward and forward. At the same time a +reverse inclination is imparted to the lateral margins bc end fg +at the other side of the machine, their inclination being +downward and forward. These positions are indicated in dotted +lines in Fig. 1 of the drawings. A movement of the cradle 18 in +the opposite direction from its normal position will reverse the +angular inclination of the lateral margins of the aeroplanes in +an obvious manner. By reason of this construction it will be +seen that with the particular mode of construction now under +consideration it is possible to move the forward corner of the +lateral edges of the aeroplane on one side of the machine either +above or below the normal planes of the aeroplanes, a reverse +movement of the forward corners of the lateral margins on the +other side of the machine occurring simultaneously. During this +operation each aeroplane is twisted or distorted around a line +extending centrally across the same from the middle of one +lateral margin to the middle of the other lateral margin, the +twist due to the moving of the lateral margins to different +angles extending across each aeroplane from side to side, so that +each aeroplane surface is given a helicoidal warp or twist. We +prefer this construction and mode of operation for the reason +that it gives a gradually increasing angle to the body of each +aeroplane from the centre longitudinal line thereof outward to +the margin, thus giving a continuous surface on each side of the +machine, which has a gradually increasing or decreasing angle of +incidence from the centre of the machine to either side. We wish +it to be understood, however, that our invention is not limited +to this particular construction, since any construction whereby +the angular relations of the lateral margins of the aeroplanes +may be varied in opposite directions with respect to the normal +planes of said aeroplanes comes within the scope of our +invention. Furthermore, it should be understood that while the +lateral margins of the aeroplanes move to different angular +positions with respect to or above and below the normal planes of +said aeroplanes, it does not necessarily follow that these +movements bring the opposite lateral edges to different angles +respectively above and below a horizontal plane since the normal +planes of the bodies of the aeroplanes are inclined to the +horizontal when the machine is in flight, said inclination being +downward from front to rear, and while the forward corners on one +side of the machine may be depressed below the normal planes of +the bodies of the aeroplanes said depression is not necessarily +sufficient to carry them below the horizontal planes passing +through the rear corners on that side. Moreover, although we +prefer to so construct the apparatus that the movements of the +lateral margins on the opposite sides of the machine are equal in +extent and opposite m direction, yet our invention is not limited +to a construction producing this result, since it may be +desirable under certain circumstances to move the lateral margins +on one side of the machine just described without moving the +lateral margins on the other side of the machine to an equal +extent in the opposite direction. Turning now to the purpose of +this provision for moving the lateral margins of the aeroplanes +in the manner described, it should be premised that owing to +various conditions of wind pressure and other causes the body of +the machine is apt to become unbalanced laterally, one side +tending to sink and the other side tending to rise, the machine +turning around its central longitudinal axis. The provision +which we have just described enables the operator to meet this +difficulty and preserve the lateral balance of the machine. +Assuming that for some cause that side of the machine which lies +to the left of the observer in Figs. 1 and 2 has shown a +tendency to drop downward, a movement of the cradle 18 to the +right of said figures, as herein before assumed, will move the +lateral margins of the aeroplanes in the manner already +described, so that the margins ad and eh will be inclined +downward and rearward, and the lateral margins bc and fg will be +inclined upward and rearward with respect to the normal planes +of the bodies of the aeroplanes. With the parts of the machine +in this position it will be seen that the lateral margins ad +and eh present a larger angle of incidence to the resisting +air, while the lateral margins on the other side of the machine +present a smaller angle of incidence. Owing to this fact, the +side of the machine presenting the larger angle of incidence +will tend to lift or move upward, and this upward movement will +restore the lateral balance of the machine. When the other side +of the machine tends to drop, a movement of the cradle 18 in the +reverse direction will restore the machine to its normal lateral +equilibrium. Of course, the same effect will be produced in the +same way in the case of a machine employing only a single +aeroplane. + +In connection with the body of the machine as thus operated we +employ a vertical rudder or tail 22, so supported as to turn +around a vertical axis. This rudder is supported at the rear +ends on supports or arms 23, pivoted at their forward ends to +the rear margins of the upper and lower aeroplanes, respectively. +These supports are preferably V-shaped, as shown, so that their +forward ends are comparatively widely separated, their pivots +being indicated at 24. Said supports are free to swing upward at +their free rear ends, as indicated in dotted lines in Fig. 3, +their downward movement being limited in any suitable manner. +The vertical pivots of the rudder 22 are indicated at 25, and one +of these pivots has mounted thereon a sheave or pulley 26, around +which passes a tiller-rope 27, the ends of which are extended out +laterally and secured to the rope 19 on opposite sides of the +central point of said rope. By reason of this construction the +lateral shifting of the cradle 18 serves to turn the rudder to +one side or the other of the line of flight. It will be observed +in this connection that the construction is such that the rudder +will always be so turned as to present its resisting surface on +that side of the machine on which the lateral margins of the +aeroplanes present the least angle of resistance. The reason of +this construction is that when the lateral margins of the +aeroplanes are so turned in the manner hereinbefore described as +to present different angles of incidence to the atmosphere, that +side presenting the largest angle of incidence, although being +lifted or moved upward in the manner already described, at the +same time meets with an increased resistance to its forward +motion, while at the same time the other side of the machine, +presenting a smaller angle of incidence, meets with less +resistance to its forward motion and tends to move forward more +rapidly than the retarded side. This gives the machine a +tendency to turn around its vertical axis, and this tendency if +not properly met will not only change the direction of the front +of the machine, but will ultimately permit one side thereof to +drop into a position vertically below the other side with the +aero planes in vertical position, thus causing the machine to +fall. The movement of the rudder, hereinbefore described, +prevents this action, since it exerts a retarding influence on +that side of the machine which tends to move forward too rapidly +and keeps the machine with its front properly presented to the +direction of flight and with its body properly balanced around +its central longitudinal axis. The pivoting of the supports 23 +so as to permit them to swing upward prevents injury to the +rudder and its supports in case the machine alights at such an +angle as to cause the rudder to strike the ground first, the +parts yielding upward, as indicated in dotted lines in Fig. 3, +and thus preventing injury or breakage. We wish it to be +understood, however, that we do not limit ourselves to the +particular description of rudder set forth, the essential being +that the rudder shall be vertical and shall be so moved as to +present its resisting surface on that side of the machine which +offers the least resistance to the atmosphere, so as to +counteract the tendency of the machine to turn around a vertical +axis when the two sides thereof offer different resistances to +the air. + +From the central portion of the front of the machine struts 28 +extend horizontally forward from the lower aeroplane, and struts +29 extend downward and forward from the central portion of the +upper aeroplane, their front ends being united to the struts 28, +the forward extremities of which are turned up, as indicated at +30. These struts 28 and 29 form truss-skids projecting in front +of the whole frame of the machine and serving to prevent the +machine from rolling over forward when it alights. The struts 29 +serve to brace the upper portion of the main frame and resist its +tendency to move forward after the lower aeroplane has been +stopped by its contact with the earth, thereby relieving the rope +19 from undue strain, for it will be understood that when the +machine comes into contact with the earth, further forward +movement of the lower portion thereof being suddenly arrested, +the inertia of the upper portion would tend to cause it to +continue to move forward if not prevented by the struts 29, and +this forward movement of the upper portion would bring a very +violent strain upon the rope 19, since it is fastened to the +upper portion at both of its ends, while its lower portion is +connected by the guides 20 to the lower portion. The struts 28 +and 29 also serve to support the front or horizontal rudder, the +construction of which we will now proceed to describe. + +The front rudder 31 is a horizontal rudder having a flexible +body, the same consisting of three stiff crosspieces or sticks +32, 33, and 34, and the flexible ribs 35, connecting said +cross-pieces and extending from front to rear. The frame thus +provided is covered by a suitable fabric stretched over the same +to form the body of the rudder. The rudder is supported from +the struts 29 by means of the intermediate cross-piece 32, which +is located near the centre of pressure slightly in front of a +line equidistant between the front and rear edges of the rudder, +the cross-piece 32 forming the pivotal axis of the rudder, so as +to constitute a balanced rudder. To the front edge of the +rudder there are connected springs 36 which springs are +connected to the upturned ends 30 of the struts 28, the +construction being such that said springs tend to resist any +movement either upward or downward of the front edge of the +horizontal rudder. The rear edge of the rudder lies immediately +in front of the operator and may be operated by him in any +suitable manner. We have shown a mechanism for this purpose +comprising a roller or shaft 37, which may be grasped by the +operator so as to turn the same in either direction. Bands 38 +extend from the roller 37 forward to and around a similar roller +or shaft 39, both rollers or shafts being supported in suitable +bearings on the struts 28. The forward roller or shaft has +rearwardly-extending arms 40, which are connected by links 41 +with the rear edge of the rudder 31. The normal position of the +rudder 31 is neutral or substantially parallel with the +aeroplanes 1 and 2; but its rear edge may be moved upward or +downward, so as to be above or below the normal plane of said +rudder through the mechanism provided for that purpose. It will +be seen that the springs 36 will resist any tendency of the +forward edge of the rudder to move in either direction, so that +when force is applied to the rear edge of said rudder the +longitudinal ribs 35 bend, and the rudder thus presents a +concave surface to the action of the wind either above or below +its normal plane, said surface presenting a small angle of +incidence at its forward portion and said angle of incidence +rapidly increasing toward the rear. This greatly increases the +efficiency of the rudder as compared with a plane surface of +equal area. By regulating the pressure on the upper and lower +sides of the rudder through changes of angle and curvature in +the manner described a turning movement of the main structure +around its transverse axis may be effected, and the course of +the machine may thus be directed upward or downward at the will +of the operator and the longitudinal balance thereof maintained. + +Contrary to the usual custom, we place the horizontal rudder in +front of the aeroplanes at a negative angle and employ no +horizontal tail at all. By this arrangement we obtain a forward +surface which is almost entirely free from pressure under +ordinary conditions of flight, but which even if not moved at +all from its original position becomes an efficient +lifting-surface whenever the speed of the machine is +accidentally reduced very much below the normal, and thus +largely counteracts that backward travel of the centre of +pressure on the aeroplanes which has frequently been productive +of serious injuries by causing the machine to turn downward and +forward and strike the ground head-on. We are aware that a +forward horizontal rudder of different construction has been +used in combination with a supporting surface and a rear +horizontal-rudder; but this combination was not intended to +effect and does not effect the object which we obtain by the +arrangement hereinbefore described. + +We have used the term 'aeroplane' in this specification and the +appended claims to indicate the supporting surface or supporting +surfaces by means of which the machine is sustained in the air, +and by this term we wish to be understood as including any +suitable supporting surface which normally is substantially +flat, although. Of course, when constructed of cloth or other +flexible fabric, as we prefer to construct them, these surfaces +may receive more or less curvature from the resistance of the +air, as indicated in Fig. 3. + +We do not wish to be understood as limiting ourselves strictly +to the precise details of construction hereinbefore described +and shown in the accompanying drawings, as it is obvious that +these details may be modified without departing from the +principles of our invention. For instance, while we prefer the +construction illustrated in which each aeroplane is given a +twist along its entire length in order to set its opposite +lateral margins at different angles, we have already pointed out +that our invention is not limited to this form of construction, +since it is only necessary to move the lateral marginal +portions, and where these portions alone are moved only those +upright standards which support the movable portion require +flexible connections at their ends. + +Having thus fully described our invention, what we claim as new, +and desire to secure by Letters Patent, is:-- + +1. In a flying machine, a normally flat aeroplane having +lateral marginal portions capable of movement to different +positions above or below the normal plane of the body of the +aeroplane, such movement being about an axis transverse to the +line of flight, whereby said lateral marginal portions may be +moved to different angles relatively to the normal plane of the +body of the aeroplane, so as to present to the atmosphere +different angles of incidence, and means for so moving said +lateral marginal portions, substantially as described. + +2. In a flying machine, the combination, with two normally +parallel aeroplanes, superposed the one above the other, of +upright standards connecting said planes at their margins, the +connections between the standards and aeroplanes at the lateral +portions of the aeroplanes being by means of flexible joints, +each of said aeroplanes having lateral marginal portions capable +of movement to different positions above or below the normal +plane of the body of the aeroplane, such movement being about an +axis transverse to the line of flight, whereby said lateral +marginal portions may be moved to different angles relatively to +the normal plane of the body of the aeroplane, so as to present +to the atmosphere different angles of incidence, the standards +maintaining a fixed distance between the portions of the +aeroplanes which they connect, and means for imparting such +movement to the lateral marginal portions of the aeroplanes, +substantially as described. + +3. In a flying machine, a normally flat aeroplane having +lateral marginal portions capable of movement to different +positions above or below the normal plane of the body of the +aeroplane, such movement being about an axis transverse to the +line of flight, whereby said lateral marginal portions may be +moved to different angles relatively to the normal plane of the +body of the aeroplane, and also to different angles relatively +to each other, so as to present to the atmosphere different +angles of incidence, and means for simultaneously imparting such +movement to said lateral marginal portions, substantially as +described. + +4. In a flying machine, the combination, with parallel +superposed aeroplanes, each having lateral marginal portions +capable of movement to different positions above or below the +normal plane of the body of the aeroplane, such movement being +about an axis transverse to the line of flight, whereby said +lateral marginal portions may be moved to different angles +relatively to the normal plane of the body of the aeroplane, and +to different angles relatively to each other, so as to present +to the atmosphere different angles of incidence, of uprights +connecting said aeroplanes at their edges, the uprights +connecting the lateral portions of the aeroplanes being +connected with said aeroplanes by flexible joints, and means for +simultaneously imparting such movement to said lateral marginal +portions, the standards maintaining a fixed distance between the +parts which they connect, whereby the lateral portions on the +same side of the machine are moved to the same angle, +substantially as described. + +5. In a flying machine, an aeroplane having substantially the +form of a normally flat rectangle elongated transversely to the +line of flight, in combination which means for imparting to the +lateral margins of said aeroplane a movement about an axis lying +in the body of the aeroplane perpendicular to said lateral +margins, and thereby moving said lateral margins into different +angular relations to the normal plane of the body of the +aeroplane, substantially as described. + +6. In a flying machine, the combination, with two superposed +and normally parallel aeroplanes, each having substantially the +form of a normally flat rectangle elongated transversely to the +line of flight, of upright standards connecting the edges of +said aeroplanes to maintain their equidistance, those standards +at the lateral portions of said aeroplanes being connected +therewith by flexible joints, and means for simultaneously +imparting to both lateral margins of both aeroplanes a movement +about axes which are perpendicular to said margins and in the +planes of the bodies of the respective aeroplanes, and thereby +moving the lateral margins on the opposite sides of the machine +into different angular relations to the normal planes of the +respective aeroplanes, the margins on the same side of the +machine moving to the same angle, and the margins on one side of +the machine moving to an angle different from the angle to which +the margins on the other side of the machine move, substantially +as described. + +7. In a flying machine, the combination, with an aeroplane, and +means for simultaneously moving the lateral portions thereof +into different angular relations to the normal plane of the body +of the aeroplane and to each other, so as to present to the +atmosphere different angles of incidence, of a vertical rudder, +and means whereby said rudder is caused to present to the wind +that side thereof nearest the side of the aeroplane having the +smaller angle of incidence and offering the least resistance to +the atmosphere, substantially as described. + +8. In a flying machine, the combination, with two superposed +and normally parallel aeroplanes, upright standards connecting +the edges of said aeroplanes to maintain their equidistance, +those standards at the lateral portions of said aeroplanes being +connected therewith by flexible joints, and means for +simultaneously moving both lateral portions of both aeroplanes +into different angular relations to the normal planes of the +bodies of the respective aeroplanes, the lateral portions on one +side of the machine being moved to an angle different from that +to which the lateral portions on the other side of the machine +are moved, so as to present different angles of incidence at the +two sides of the machine, of a vertical rudder, and means +whereby said rudder is caused to present to the wind that side +thereof nearest the side of the aeroplanes having the smaller +angle of incidence and offering the least resistance to the +atmosphere, substantially as described. + +9. In a flying machine, an aeroplane normally flat and +elongated transversely to the line of flight, in combination +with means for imparting to said aeroplane a helicoidal warp +around an axis transverse to the line of flight and extending +centrally along the body aeroplane in the direction of the +elongation aeroplane, substantially as described. + +10. In a flying machine, two aeroplanes, each normally flat and +elongated transversely to the line of flight, and upright +standards connecting the edges of said aeroplanes to maintain +their equidistance, the connections between said standards and +aeroplanes being by means of flexible joints, in combination +with means for simultaneously imparting to each of said +aeroplanes a helicoidal warp around an axis transverse to the +line of flight and extending centrally along the body of the +aeroplane in the direction of the aeroplane, substantially as +described. + +11. In a flying machine, two aeroplanes, each normally flat +and elongated transversely to the line of flight, and upright +standards connecting the edges of said aeroplanes to maintain +their equidistance, the connections between such standards and +aeroplanes being by means of flexible joints, in combination +with means for simultaneously imparting to each of said +aeroplanes a helicoidal warp around an axis transverse to the +line of flight and extending centrally along the body of the +aeroplane in the direction of the elongation of the +aeroplane, a vertical rudder, and means whereby said rudder is +caused to present to the wind that side thereof nearest the side +of the aeroplanes having the smaller angle of incidence and +offering the least resistance to the atmosphere, substantially +as described. + +12. In a flying machine, the combination, with an aeroplane, of +a normally flat and substantially horizontal flexible rudder, +and means for curving said rudder rearwardly and upwardly or +rearwardly and downwardly with respect to its normal plane, +substantially as described. + +13. In a flying machine, the combination, with an aeroplane, of +a normally flat and substantially horizontal flexible rudder +pivotally mounted on an axis transverse to the line of flight +near its centre, springs resisting vertical movement of the +front edge of said rudder, and means for moving the rear edge of +said rudder, above or below the normal plane thereof, +substantially as described. + +14. A flying machine comprising superposed connected aeroplanes +means for moving the opposite lateral portions of said +aeroplanes to different angles to the normal planes thereof, a +vertical rudder, means for moving said vertical rudder toward +that side of the machine presenting the smaller angle of +incidence and the least resistance to the atmosphere, and a +horizontal rudder provided with means for presenting its upper +or under surface to the resistance of the atmosphere, +substantially as described. + +15. A flying machine comprising superposed connected +aeroplanes, means for moving the opposite lateral portions of +said aeroplanes to different angles to the normal planes +thereof, a vertical rudder, means for moving said vertical +rudder toward that side of the machine presenting the smaller +angle of incidence and the least resistance to the atmosphere, +and a horizontal rudder provided with means for presenting its +upper or under surface to the resistance of the atmosphere, said +vertical rudder being located at the rear of the machine and +said horizontal rudder at the front of the machine, +substantially as described. + +16. In a flying machine, the combination, with two superposed +and connected aeroplanes, of an arm extending rearward from each +aeroplane, said arms being parallel and free to swing upward at +their rear ends, and a vertical rudder pivotally mounted in the +rear ends of said arms, substantially as described. + +17. A flying machine comprising two superposed aeroplanes, +normally flat but flexible, upright standards connecting the +margins of said aeroplanes, said standards being connected to +said aeroplanes by universal joints, diagonal stay-wires +connecting the opposite ends of the adjacent standards, a rope +extending along the front edge of the lower aeroplane, passing +through guides at the front corners thereof, and having its ends +secured to the rear corners of the upper aeroplane, and a rope +extending along the rear edge of the lower aeroplane, passing +through guides at the rear corners thereof, and having its ends +secured to the front corners of the upper aeroplane, +substantially as described. + +18. A flying machine comprising two superposed aeroplanes, +normally flat but flexible, upright standards connecting the +margins of said aeroplanes, said standards being connected to +said aeroplanes by universal joints, diagonal stay-wires +connecting the opposite ends of the adjacent standards, a rope +extending along the front edge of the lower aeroplane, passing +through guides at the front corners thereof, and having its ends +secured to the rear corners of the upper aeroplane, and a rope +extending along the rear edge of the lower aeroplane, passing +through guides at the rear corners thereof, and having its ends +secured to the front corners of the upper aeroplane, in +combination with a vertical rudder, and a tiller-rope connecting +said rudder with the rope extending along the rear edge of the +lower aeroplane, substantially as described. + ORVILLE WRIGHT. + WILBUR WRIGHT. +Witnesses: +Chas. E. Taylor. +E. Earle Forrer. + + + + APPENDIX C + +Proclamation published by the French Government on balloon +ascents, 1783. + + NOTICE TO THE PUBLIC! PARIS, 27TH AUGUST, 1783. + +On the Ascent of balloons or globes in the air. The one +in question has been raised in Paris this day, 27th August, +1783, at 5 p.m., in the Champ de Mars. + +A Discovery has been made, which the Government deems it right to +make known, so that alarm be not occasioned to the people. + +On calculating the different weights of hot air, hydrogen gas, +and common air, it has been found that a balloon filled with +either of the two former will rise toward heaven till it is in +equilibrium with the surrounding air, which may not happen until +it has attained a great height. + +The first experiment was made at Annonay, in Vivarais, MM. +Montgolfier, the inventors; a globe formed of canvas and paper, +105 feet in circumference, filled with heated air, reached an +uncalculated height. The same experiment has just been renewed +in Paris before a great crowd. A globe of taffetas or light +canvas covered by elastic gum and filled with inflammable air, +has risen from the Champ de Mars, and been lost to view in the +clouds, being borne in a north-westerly direction. One cannot +foresee where it will descend. + +It is proposed to repeat these experiments on a larger scale. +Any one who shall see in the sky such a globe, which resembles +'la lune obscurcie,' should be aware that, far from being an +alarming phenomenon, it is only a machine that cannot possibly +cause any harm, and which will some day prove serviceable to the +wants of society. + +(Signed) DE SAUVIGNY. +LENOIR. + + + + + +End Project Gutenberg Etext of A History of Aeronautics + diff --git a/old/haero10.zip b/old/haero10.zip Binary files differnew file mode 100644 index 0000000..d9257f8 --- /dev/null +++ b/old/haero10.zip |