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@@ -0,0 +1,13344 @@ +The Project Gutenberg EBook of A History of Aeronautics, by E. Charles Vivian + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: A History of Aeronautics + +Author: E. Charles Vivian + +Posting Date: July 26, 2008 [EBook #874] +Release Date: April, 1997 + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK A HISTORY OF AERONAUTICS *** + + + + +Produced by Dianne Bean + + + + + +A HISTORY OF AERONAUTICS + +by E. 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 man, 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 case, 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 intimately 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 Kill 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 +8,000 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 100 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 half 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 Handley-Page 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 that 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-than-air +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 these observations 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 of Project Gutenberg's A History of Aeronautics, by E. 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