Transcriber’s Note

Some spellings have been left as is e.g. Wavrille/Waville

Hyphenations have been standardised.

Changes made are noted at the [ end of the book.]

AIRCRAFT

Courtesy of Aerial Age Weekly.

The NC-4 flying-boat, showing the arrangement of the motors.

It is equipped with four Liberty 450 h.-p. engines. It flew from Rockaway, New York, to Plymouth, England, commanded by Lieutenant-Commander A. C. Read, U. S. N.

AIRCRAFT

ITS DEVELOPMENT IN WAR AND PEACE AND
ITS COMMERCIAL FUTURE

BY EVAN JOHN DAVID

ASSOCIATE EDITOR OF “FLYING”

FULLY ILLUSTRATED

NEW YORK
CHARLES SCRIBNER’S SONS
1919

Copyright, 1919, by
CHARLES SCRIBNER’S SONS

Copyright, 1919, by the Curtis Publishing Co.

Published September, 1919

TO
ALL WHO HELPED ME TO OBTAIN AN
EDUCATION

PREFACE

The object of this book is to explain the fundamental principles of aeronautics and to point out the historic development of both the heavier-than-air and the lighter-than-air craft. The treatment is simple. Technical phrases have been avoided wherever possible. Emphasis has been laid on the changes in the design or construction of aeroplanes and dirigibles, which show the evolution of flight and aircraft from early experiments with balloons and gliders to the transatlantic flights of the NC-4, the Vickers “Vimy” Bomber, and the R-34. Only those things have been singled out which indicated a step forward in the science of aeronautics. Emphasis is placed upon the commercial accomplishments of the aeroplane and the dirigible, and many of the present uses and future possibilities of aircraft as a commercial vehicle have been pointed out.

I am indebted to many sources for the information contained herein. Mr. Henry Woodhouse, the well-known aeronautical authority and editor of Flying Magazine and author of the text-books on military and naval aeronautics, has been the source of much of my information, and the volumes of Flying Magazine have supplied me with much historic data. Aerial Age Weeklyand Mr. G. Douglas Wardrop, the managing editor, have also been very helpful. The British periodicals Flight, The Aeroplane, and Aeronautics have furnished me with many facts regarding British aircraft. The articles of Mr. C. G. Grey, the editor of The Aeroplane, dealing with the growth of heavier-than-air machines, and of Mr. W. L. Wade on lighter-than-air craft, have been the source of many of the facts regarding the evolution of aircraft. Many other aeronautical authorities have afforded statistics, facts, etc.

Evan John David.

New York, August 12.

CONTENTS

ILLUSTRATIONS

AIRCRAFT

CHAPTER I

THE FIRST BALLOONS

THE DEVELOPMENT OF THE FREE BALLOON—THE CAPTIVE BALLOON—THE DIRIGIBLE—THE BLIMP—THE KITE BALLOON

Ever since man first noticed the flight of a bird through the air he has longed to fly. How often, during the countless ages of unrecorded time, he attempted to soar above the earth we cannot know. That he tried often and failed always we have ample proof; indeed, the phrase, “might as well try to fly,” expressed the acme of the impossible. That many scientific men for nearly two thousand years believed that eventually a mechanical means could be devised to lift man off the ground like the wings of a bird and to propel him through the air, we have evidence in their writings and the history of their lives.

Ancient mythology is full of stories of the heroes who attempted to imitate the flight of the fowls of the air. The earliest efforts of the aeronauts themselves appear to have been along this line. Naturally many of the experimenters lost their lives. A mere enumeration of their names would take too much space for this volume.

Perhaps these struggles to use wings suggested to the tight-rope walker Allard the possibility of performing a novel stunt. At any rate, in 1660 he successfully made several glides for exhibition purposes in France. Seventeen years later another Frenchman named Bosnier also made spectacular glides. These experiments, however, led to the invention of the glider, which finally developed into the aeroplane or the heavier-than-air machine.

A glider consists of a rigid rectangular plane constructed of frail framework, similar to a kite, and covered with linen or cloth, much like the wing of a modern aeroplane. This plane surface might be a dozen or more feet long and two or more feet wide. The early experimenters jumped off hills with this plane fastened to their arms or shoulders, and balancing themselves in the centre, glided several feet over the ground, keeping their equilibrium by means of their feet. Later two planes fastened together like a box-kite were employed, with the flier stretched out on his stomach on the lower planes. Lillienthal and even the Wright brothers learned most about longitudinal and lateral balance by gliding on gliders of the last type. A great deal of sport can be had with these man-carrying kites even to-day.

The experiments of the two French brothers, Joseph and Jacques Montgolfier, with paper bags inflated with hot air started a new period of development in aeronautics, for the paper bags suggested the silk ones, which were, of course, much lighter. On September 19, 1783, they gave an exhibition before the royal family at Versailles.

The authors of the first ascension, the first actual step in the conquest of the air, were two Frenchmen, Marquis d’Arlandes and Pilâtre de Roziers, who made the first ascension near Paris on November 21, 1783. From that time on free ballooning became a very popular sport. The escaping of the hot air or gas, forcing the balloon to descend too suddenly, led to the invention of the parachute as a means of descending slowly from the collapsing bag. The possibility of using this type of balloon for observation purposes was realized by the French, and the first recorded battle that the captive balloon was employed in was at Fleurus June 26, 1794, thus supplying “aerial eyes” for the French army to observe the movements of the Austrians.

The free balloon was, however, entirely at the mercy of the winds, and the captive balloon could not be moved about readily, so that it was thus limited in its sphere of observation, except when attached to some movable conveyance. This showed the necessity of inventing some means of propulsion and steering. The first experiments were attempts to row ordinary spherical balloons, as you would a boat, but the earliest record of any definite progress being achieved in forcing a lighter-than-air craft through the air was the experiment in France of two brothers named Robert in 1784. They constructed a melon-shaped balloon, 52 feet long and 32 feet in diameter, made of proofed silk. The gas employed was pure hydrogen. Underneath this envelope was suspended a long, narrow car, in general idea not unlike that used on some modern airships; and three pairs of oars with blades made like racquet-frames covered with silk, and a rudder of similar material, were the only implements for navigation.

The two brothers and their brother-in-law went up in the apparatus and succeeded in describing a curve of one kilometre radius, which showed, at any rate, that they could deviate slightly from the direction of the feeble wind then prevailing.

The development of the steam-engine was potent with suggestions for aerial navigation of a dirigible. Thus, on December 24, 1852, Henry Gifford, another Frenchman, first ascended in a dirigible balloon. It was spindle-shaped, 143 feet long and 39 feet in diameter. It was driven by a 3 horse-power steam-engine and an 11-foot screw propeller. He went out from the Hippodrome in Paris and made six miles per hour relative to the air and several successful landings. This was the first recorded dirigible flight.

A decade later, Tissandier, with a spindle-shaped balloon, much on the lines of those of his predecessors, succeeded in reaching a speed of eight miles an hour with the aid of an electric motor and a bichromate-of-potash battery.

Captain Charles Renard brought the airship another stage toward realization by building an envelope with a true stream-line. The method of suspending the car was of the type adopted by later builders, namely, to place an enormous sheet over the back of the airship and to attach suspensory cords to its edges. This airship had a cubic capacity of 66,000 feet, and was kept rigid by means of an internal air balloonet or interior gas-bag which was confined to a definite shape by an outer framework or cover. This balloonet was kept full by a fan-blower coupled to the motor.

The car was 108 feet long, and really served as a spar employed in later airships of what became known as the semirigid type.

An electric motor was installed, weighing 220 pounds, which developed 9 horse-power. The battery composed of chlorochromic salts, delivered one shaft horse-power for each 88 pounds, and this great weight seriously handicapped the performance of the airship. The first trials were made in 1884, and apparently within the limits of its propulsive power the airship was an unqualified success, so far as navigation was concerned. On one occasion it flew around Paris at an average speed of 14½ miles an hour.

As early as 1872 Herr Hanlein, in Germany, built an airship of quite reasonable proportions, propelled by a 6 horse-power Lenoir gas-engine. Apparently the engine was run on gas from the envelope. A speed of 10 miles an hour or so was achieved.

In 1879 Baumgartner and Wolfert built an airship with a Daimler benzine motor. An ascent was made at Leipzig in 1880, but owing to improper load distribution the vessel got out of control and was smashed on the ground.

The first rigid dirigible with aluminum framework was built by an Austrian named Schwartz in 1897. This was the prototype of the Zeppelin, and no practical rigid lighter-than-air ship could now be lifted by hydrogen unless it had an aluminum framework.

The invention of the gasoline engine was another tremendous advantage to the Zeppelin.

M. Santos Dumont built an extraordinary collection of small airships during a period of several years commencing in 1898. His first effort was a cylinder of varnished Japanese silk, 82½ feet long and 11 feet in diameter, with pointed ends, which gave it a capacity of about 6,300 cubic feet. It was fitted with the usual internal air balloonet and a 3½ horse-power motor-cycle engine weighing 66 pounds. The engine was fitted to an ordinary balloon basket, which hung beneath the envelope and drove a two-blade propeller. The pilot also sat in the basket. The poise of the vessel was controlled by shifting weights, and steering was effected with a silk rudder stretched over a steel frame. In September, 1898, this miniature airship left the Zoological Gardens at Paris in the face of a gentle wind, and performed all sorts of evolutions in the neighborhood.

M. Dumont’s No. 5 was fitted with a four-cylinder, air-cooled motor driving an enormous propeller of 26 feet in diameter, which gave a thrust of 120 pounds at 140 revolutions per minute. There is, however, some difference between this number of revolutions and the 1,400 per minute now generated by all the standard aeronautical motors. Among other novelties water ballast was used and piano wires replaced the old type suspension cords.

No account of the lighter-than-air machine would be complete without mentioning the man after whom the Zeppelins were named. As a matter of fact Count Zeppelin added nothing strikingly new to his airships—he simply made them much larger than any of their predecessors; thus increasing the net lifting power and multiplying the number of engines and the horse-power.

Count Ferdinand von Zeppelin first began to experiment in 1898. His first rigid dirigible was 410 feet and the gas-bags contained 400,000 cubic feet of hydrogen, and the net lifting power, after allowing for the engines, fuel, gear, etc., was about two tons. The framework was of aluminum latticework divided into seventeen compartments, fifteen of which had gas-bags. Two cars were attached and in each was a 16 horse-power German Daimler gasoline motor driving two propellers, and the machine gained a speed of 15 miles an hour, which was far in advance of any airship of that period.

By this time practically all the fundamentals of construction of dirigibles had been incorporated in these airships. Further refinements were made, more engines and balloonets added, and the length of the dirigible and the volume of hydrogen gas used for inflation was increased, as was also the horse-power, but nothing more in the way of radical changes was employed to the end of the Great War. Therefore a description of the Zeppelin which was brought down in England will serve as an excellent idea of the size of these mammoth airships.

The Zeppelin forced to land in Essex measured from 650 feet to 680 feet in length and measured 72 feet across its largest diameter. The vessel was of the stream-line form, with a blunt, rounded nose, and a tail that tapered off to a sharp point. The framework was made of longitudinal latticework girders, connected together at intervals by circumferential latticework ties, all made of an aluminum alloy resembling duraluminum. The whole was braced together and stiffened by a system of wires, arrangements being provided by which they could be tightened up when required. The weight of the framework is reckoned to be about 9 tons, or barely a fifth of the total of 50 tons attributed to the airship complete with engines, fuel, guns, and crew. There were 24 balloonets arranged within the framework, and the hydrogen capacity was 2,000,000 cubic feet.

A cat-walk, an arched passage with a footway nine inches wide, running along the keel enabled the crew, which consisted of twenty-two men, to move about the ship and get from one gondola to another. This footway was covered with wood, a material which, however, was evidently avoided as much as possible in the construction of the ship. The gondolas, made of aluminum alloy, were four in number; one was placed forward on the centre line, two were amidships, one on each side, and the fourth was aft, again on the centre line.

The vessel was propelled—at a speed, it is thought, of about sixty miles an hour in still air—by means of six Maybach-Mercedes gasoline engines of 240 horse-power each, or 1,440 horse-power in all. Each had six vertical cylinders with overhead valves and water cooling, and weighed about 1,000 pounds. They were connected each to a propeller shaft through a clutch and change-speed gear, and also to a dynamo used either for lighting or for furnishing power to the wireless installation. One of these engines with its propeller was placed at the back of the large forward gondola, two were in the amidships gondolas, and three were in the aft gondola. In the last case one of the propellers was in the centre line of the ship, and the shafts of the other two were stayed out, one on either side. With the object of minimizing air resistance the stays were provided with a light but strong casing of two or three ply wood, shaped in stream-line form. The gasoline tanks had a capacity of 2,000 gallons, and the propeller shafts were carried in ball bearings. The date, July 14, 1916, marked on one of them, is thought to indicate the date of the launching or commissioning of the vessel.

Forward of the engine-room of the forward gondola, but separated from it by a small air space, was first the wireless operator’s cabin and then the commander’s room. The latter was the navigating platform, and in it were concentrated the controls of the elevators and rudder at the stern, the arrangement for equalizing the levels in the gasoline and water tanks, the engine-room telegraphs, and the switchboard of the electrical gear for releasing the bombs. Provision was made for carrying sixty of the latter in a compartment amidships, and there was a sliding shutter, worked from the commander’s cabin, which was withdrawn to allow them to fall freely. Nine machine-guns were carried. Two of these, of 0.5-inch bore, were mounted on the top of the vessel, and six of a smaller caliber were placed in the gondolas—two in the forward, one each in the amidships ones, and two in the aft one. The ninth was carried in the tail.

The separate gas-bags were a decided advantage over the free balloon and earlier airships which carried all the gas in one compartment, for if the latter sprang a leak for any reason it had to descend, whereas the Zeppelin could keep afloat with several of the separate compartments in a complete state of collapse.

Since the Zeppelin, like all airships, is buoyed up by hydrogen gas which is .008 lighter than air, the dirigible was sent up by the simple expedient of increasing the volume of gas in the envelope until the vessel arose. This was done by releasing the gas for storage-tanks into the gas-bags. In order to head the nose up, air was kept in certain of the rear bags, thus making the tail heavier than the forward part, which naturally rose first. Steering was done by means of the rudder or the engines, or both, and the airship was kept on an even keel by use of the lateral planes. The airship could be brought down by forcing the gas out of the bags into the gas-tanks, thus decreasing the volume and by increasing the air in the various compartments.

This airship had a flying radius of 800 miles and could climb to 12,000 feet, and could carry a useful load of four tons and could remain in the air for fifty hours. Without a doubt it is one of the largest rigid dirigibles ever built.

Courtesy of Flying Magazine.

Observation balloon about to ascend.

These balloons were stationed at intervals along the battle-fronts.

Owing to the great amount of material used, the immense cost, and the time necessary to construct a Zeppelin, under the urgent demands of war, the British built and developed a small rigid dirigible measuring between 200 and 250 feet in length, buoyed up by two balloonets, one front and back, and carrying a fuselage and one aeromotor, and propeller situated directly under the cigar-shaped airship. These vessels made about fifty miles an hour, carried two men, were fitted with wireless, and made excellent scouts over the North Sea and waters contiguous to allied territory, looking for submarines. These air-vessels were called Blimps.

The kite balloon was cigar-shaped and non-rigid, with only a basket suspended underneath. It was attached to a rope and was lifted by the gas and the wind which passed under the fins, which extended from the sides near the rear. It combined the principle of the free balloon and the man-lifting kites.

These balloons were used very extensively in the Great War for observation purposes. Suspended at the end of a cable attached to a donkey-engine or a windlass at an altitude of 3,000 feet, they afforded the best observation for artillery-fire, and by means of the telephone in the basket the observer could keep headquarters well informed of troop movements within a radius of many miles.

Naturally it was the special delight of the aeroplanes to dive down on these stationary balloons and by means of incendiary bullets to ignite the gas. It was dangerous work for the heavier-than-air machines, for all the way down the antiaircraft guns blazed away. It was also dangerous work for the observers in the imprisoned balloon, who often had to jump with their parachutes in order to escape.

Thus by 1918 man had devised an aircraft that could propel him through the air faster than the eagle, farther than the sea-gull, and soar aloft higher than the lark! No wonder he felt that no mechanical feat was impossible.

CHAPTER II

THE AEROPLANE

EXPERIMENTS WITH PLANES—LILLIENTHAL’S GLIDER—LANGLEY’S AERODROME—SUCCESS OF THE WRIGHTS—FIRST AEROPLANE FLIGHTS

The evolution of the heavier-than-air flying-machine, like that of the lighter-than-air, covers a long period of time, and was fraught with many difficulties and dangers. For ages many scientific men played with the idea, but owing to the lack of motive power light enough to be mounted on a glider yet supplying sufficient strength to drive a set of planes through the air at 45 miles an hour, very little progress was made until the perfection of the steam-engine and the development of the gasoline motor. Indeed, such things as lateral and longitudinal balance of planes, as well as steering by rudder, could only be worked out to a successful conclusion by man-carrying gliders moving at a sufficient velocity to keep them off the ground. Since no mechanical device driven by man could supply this want, the science lacked practical development until the last quarter of a century.

Perhaps the acrobatic tight-rope walker Allard, in 1660, was the first to make long glides during an exhibition of his profession. But nothing of material advantage to the science was accomplished.

In 1809 Sir George Cayley, an Englishman, planned an aeroplane with oblique planes, resting on a wheeled chassis, fitted with propellers, motors, and steering devices. The machine was never built.

In 1843 another Englishman, Samuel Henderson, designed and patented an “aerial steam carriage,” which was to be an aeroplane of immense size to be used for passenger carrying. Like the former it was never built.

M. Strongfellow, another Englishman, designed a triplane, which he fitted with a tail and two propellers. A triplane differs from a biplane only in that a third plane is superimposed over the second plane at the same distance as the second plane was above the first or monoplane. This model was shown at the exhibition of the Aeronautical Society of Great Britain in 1868. As in the case of previous inventors, nothing in this model indicated that he had any comprehension of the principles of stability or knowledge of the lifting capacity of surfaces, or the power required for dynamic flight.

In 1872 a French inventor, named Alphonse Penaud, constructed a small monoplane. It was only a toy—two flimsy wings actuated by a twisting rubber—but it had fore-and-aft stability. These model aeroplanes, however, aided the science materially by demonstrating the necessity for stability before planes could be steered through space. Subsequently, in 1875, Penaud took out a patent on a monoplane fitted with two propellers and having controlling devices. But this was not built, principally because it would have required a light motor, and the lightest available at that time weighed over 60 pounds per horse-power. To-day most aeromotors weigh less than two pounds per horse-power.

Louis Pierre Mouillard, a Frenchman, who had observed that large birds in flight, while seeming at rest, could go forward against the wind without a stroke of the wings, constructed a number of gliders built on the principle of bird wings, and experimented with gliding. He published a work called “L’Empire de l’Air,” which inspired many late experiments with gliders.

The net results of all these designs and experiments of these inventors demonstrated that thin, rigid surfaces of a certain shape, structure, and design could support weights when driven through the air at a sufficient velocity. Further than that they contributed practically nothing to the science of aviation.

As a matter of fact, it was toward the close of the nineteenth century before means were found to make an aeroplane rise from the ground, maintain its equilibrium. These latter-day pioneers of aviation were divided into two schools. The first sought to achieve soaring flights by means of large kitelike apparatus, which enabled them to fly in the air against winds, their machines being lifted up and supported by the inertia of the air as kites are. The second sought to develop power flight, that is, to send their kitelike machines through the air at high speed, being tracted or propelled by revolving screws actuated by motor power.

The most prominent experimenters of the first glider school were Otto Lillienthal, a German, P. L. Pitcher, an Englishman, Octave Chanute, and J. J. Montgomery.

Lillienthal was the first man to accomplish successful flights by means of artificial wing surfaces. In 1894, after much experimenting, he constructed rigid wings which he held to his shoulders. He used to run down hills with them until the velocity he was moving at would catch the air and lift him completely off the ground. By observation of birds he saw that their wings were arched, which suggested reason for failures of previous experiments in this line; so afterward his planes were arched also. He was the first man to be lifted off the ground by plane surfaces, and to demonstrate that arched surfaces were necessary to sustained flight of heavier-than-air craft.

To the rigid wings Lillienthal fastened a rigid tail and this constituted his glider. There were no control levers and the only way he could steer was by shifting the balance, by use of his legs, in one direction or another. By means of an artificial hill he had constructed he could coast downward for some distance without striking the ground. He was unfortunately killed in one of these experiments in 1896.

Chanute’s experiments in gliding were similar to Lillienthal’s, but they were conducted on the sand-dunes along Lake Michigan, near Chicago. His apparatus was more strongly constructed, of trussed biplane type—a construction suggested to him by his experience in bridge building, and one which persists to-day as the basis of strength in our present military biplanes. In design it was similar to a box kite, and it was the kind which the Wrights adopted for their experiments.

The leaders of the second school were: Clement Ader (1890-97), Sir Hiram Stevens Maxim (1890-94), and Samuel Pierpont Langley (1895-1903).

Clement Ader, the famous French scientist, under the auspices of the French Government, conducted experiments from 1890 to 1897. In 1890 he filled his Arion, a boat-shaped machine with two propellers, with a steam-engine, but the apparatus never flew. He finished his next machine in 1897 after six years of hard work. It was large enough to carry a man, but, like its predecessor, it never left the ground, and the French Government refused to support his experiments further.

While Ader was making his experiments in France, Sir Hiram S. Maxim was at work constructing a large multiplane for the English Government, which he fitted with two steam-engines of 175 horse-power. But like Ader’s experiments it toppled over at the first trial and was badly damaged, and the British Government refused further backing.

The experience of Samuel Pierpont Langley in America is not unlike the experience of Ader in France and Maxim in England. He was employed by the Board of Ordnance and Fortification of the United States army to construct the “Aerodrome” of his own invention. Congress appropriated $50,000 for the purpose. Langley’s machine was a tandem monoplane, 48 feet from tip to tip, and 52 feet from bowsprit to the end of its tail. It was fitted with a 50 horse-power engine and weighed 830 pounds. The trials of this aerodrome, two attempts to launch it, were made on October 7 and December 8, 1903. On both occasions the aerodrome became entangled in the defective launching apparatus, and was thrown headlong into the Potomac River—on which the launching trials were made. Following the last failure, when the aerodrome was wrecked, the press ridiculed the whole enterprise, and Congress refused to appropriate money for further experiments. The Langley aerodrome, fitted with a Curtiss motor and Curtiss controls, flew in 1913-14.

As with experiments of the first school they did not attain practical results. The machines were usually wrecked at the first trial without giving any clew to the nature or whereabouts of the trouble. Although Langley’s machines were reconstructed and flown later this should not detract in any way from the fame of the Wright brothers, Orville and Wilbur, who really were the first to construct an aeroplane which was driven by a gasoline motor, lifting a man off the ground, and pursuing a steered and sustained flight through the air.

The experiments of Lillienthal and his death in his glider were the direct incentives to the Wright brothers to conduct their investigations with gliders. The Lillienthal way of balancing the planes by swinging his legs they judged to be a poor means of controlling the direction of the flight. So they set out to discover another method of controlling the stability of the planes. Their experiments began in the fall of 1900 at Kitty Hawk, North Carolina, as Mr. Henry Woodhouse, the aeronautical authority, has pointed out. They took all the theories of flight and tried them one by one, only to find, after two years of hard, discouraging work, that they were based more or less on guesswork. Thereupon they cast aside old theories and patiently put the apparatus through innumerable gliding tests, ever changing, adding, modifying—setting down the results; after each glide comparing, changing again and again, until they finally constructed a glider which was easy to balance both laterally and longitudinally. But in order to control fore-and-aft balance they had to eliminate Lillienthal’s method of swinging his legs and substitute a horizontal elevator. This elevator was raised and lowered by a lever operated by the pilot stretched out on the centre of the lower wing of the glider. This device kept the glider level with respect to the ground. In fact, this elevator was absolutely necessary to prevent the planes from diving up or down, for if the pilot found the glider pitching too much forward, tending to dive, he would tilt the elevator upward by means of the lever, thus pulling the nose of the glider back into its proper position. At first the Wrights built the elevator in front of the planes so that they could see and study its effect. They soon discovered that the control of the glider was much better with the elevator. This elevator has been incorporated as a standard fin on the tail of the fuselage of every aeroplane and is one of the chief factors in steering up or down.

Having completely mastered this most important step, the Wrights next took up the problem of lateral control. The natural tendency of the glider was to flop about like a kite with too light a tail. In order to correct this lateral instability the Wrights determined to make the air itself, rather than gravity, supply this balance, instead of Lillienthal’s method of swinging his legs from side to side by observing closely the way in which a pigeon secures its lateral balance by varying the angle of attack with its two wings, whereby one wing would lift more forcibly than the other, thereby turning the bird in any direction around any given axis of flight. In order to accomplish this variation the Wrights made the ends of the glider loose while the rest remained rigid. Then by a system of wires operated from a lever they could warp these wing ends of the glider, one to present a greater angle of attack to the air and the other a smaller angle, just as the pigeon did. In other words, by pulling down the rear edge of the tip of one wing and by pulling up the extreme edge of the other the angles of the wings were varied with respect to the way in which they cut through the air on very much the same principles as the tail elevator on the fuselage. Also, if a flat surface moves through the air horizontal to the ground, if you tipped the rear edge upward the air would strike it on that edge and have a tendency to force it down, thus forcing the forward edge upward. To pull it in the other direction would cause the opposite effect. The Wrights were first to incorporate this in a glider or aeroplane. They patented it, and although a hinge, called an aileron, was later attached to the end of the wings of an aeroplane to produce the same effect and at the same time to allow more rigid construction of the ends of the wings, nevertheless this idea was distinctly a Wright discovery and innovation.

Courtesy of Flying Magazine.

The Wright flyer after the epoch-making flight at Kitty Hawk, N. C., December, 1903.

This was the first successful motor-driven heavier-than-air craft to lift a man off the ground and carry him over a steered course. It had one 16 h.-p. motor with a chain-drive to two propellers. The elevators were in front of the machine. The plane resembles a glider or a box kite and the wings could be warped for steering.

But that was not all the Wright brothers did to make man-flight over a sustained and steered course in a heavier-than-air machine possible. Directional control or power to steer the glider in a straight line or to vary it had not yet been acquired, so the Wrights installed a vertical rudder which they also operated by lever, just as the rudder on a power-boat is controlled, and the effect on directional steering was the same. Indeed, passage through the medium of the air is in many ways similar to passage through water. Thus the moment the glider swerved from right to left the rudder was pulled in the opposite direction and the planes came back to the steered course.

But this was not invented at once nor installed until after the Wrights discovered that whenever the glider was in flight the effect of warping the wings to control the rolling had a serious unexpected secondary effect, namely, a tendency for the high wing, which they desired to bring down, to advance faster through the air than the low wing, and solely by its higher velocity to develop a higher lifting capacity and thus to neutralize the benefit of the warp. After much experimenting they hit upon the rudder idea and that corrected the difficulty.

Thus the Wrights gained complete mastery of the glider; they could steer it up and down, turn it from right to left, and bring it back safely to the earth. This is the basis of the Wright patents to-day.

The next thing to be done was to install upon an aeroplane a power plant sufficient to drive it through the air fast enough to make the air lift it off the ground and sustain it in the “liquid blue” until the pilot saw fit to glide to the earth again. This was by no means a simple matter, for from 1900, when the Wrights began their glider experiments, to 1903, when they made their first flight, the gasoline motor was in its impotent infancy. They set about building a small light motor, however, to install in their planes.

In the meantime they experimented further with wing surfaces. Langley and Chanute had proved flat wings inefficient and curved wings necessary for lifting capacity. Of course, those early experimenters did not know how much those curvatures affected the climbing angle of a glider, so the Wrights set out to find out by using the wind-tunnel method and testing scale models in the same, with a blast of air generated by an engine-driven fan. This tunnel was cylindrical in form, sixteen inches in diameter. The smaller models of wings were hung in the centre, the air-blast turned on, and the balance arm, which projected into the tunnel and on which the wings were mounted, measured the air forces and the efficiency of the varied wing shapes from the standpoint of rounded wing tips and curvature.

Data acquired in experimenting with their six-inch model biplane in this determined them to build their aeroplane on that scale, even though it was discovered that two wings together were less efficient than one wing by itself. The rigidity of two wings added a safety factor, so they adopted the biplane or two-plane surface rather than the monoplane or one-plane surface.

In these experiments the Wrights also discovered that all surfaces shaped like a fish offered less resistance to the air than blunter obtuse surfaces, so they adopted the stream-line method in construction of struts or supports to the two wings, so that now all surfaces that cut the air in the forward progress of the planes are rounded off so that the air slips off with the least resistance. This was an important discovery, for later when the enclosed fuselage or body in which the aviator sits was constructed it had much to do in determining its shape and design.

Propellers had already been experimented with as a means of propulsion through the air. Because of the low horse-power at which they were driven very little scientific data as to propeller efficiency had been compiled. Because the first motor constructed by the Wrights had only 16 horse-power at maximum speed, which soon fell off to 12 horse-power, the two propellers mounted on their first machine developed a high propeller efficiency. To-day propeller efficiency has reached approximately 70 per cent of efficiency, and much study has been devoted to the propeller.

Because no gasoline motor was in existence light enough to mount on their glider the Wrights built their own in their shops in Dayton. It was a four-cylinder water-cooled upright motor, and it could develop 12 horse-power. The engine was mounted on the rear of the planes of the glider and by a chain drive propelled the two blades mounted in the rear of the two planes, thus making a pusher type of aeroplane. The estimate of the total weight of the machine and the operator was between 750 and 800 pounds.

With this machine, on December 17, 1903, Wilbur Wright made the world’s first sustained steered flight of 852 feet in 59 seconds in a heavier-than-air machine. To them really belongs the honor of having invented the aeroplane and of having demonstrated the feasibility of navigating the air in a heavier-than-air machine. It is true that the Frenchman M. Bleriot was the man who covered the fuselage, put the engine in front of the aviator, and constructed a monoplane similar in shape to a bird. Nevertheless, it is the Wrights who built the aeroplane which met all the fundamental requirements of flight through the air.

CHAPTER III

WHY AN AEROPLANE FLIES

THE HELICOPTER—THE ORNITHOPTER—WING SURFACE—FLYING SPEED—LANDING SPEED—EFFECT OF MOTORS—THE SEAPLANE

The heavier-than-air machines are divided into three classes. The helicopter is a machine which theorists of that school believe can fly straight up into the sky because its air screw propeller works on a vertical axis. This type of aircraft has never been successful, for the reason that the propeller does not lift. It simply pulls a stream-lined surface through the air. The lifting must be done by planes.

The ornithopter is another heavier-than-air craft which seeks to fly by flapping wings like a bird. The effort to build this type of machine is as old as human desire to imitate the fowls of the air and it has been as unsuccessful as the helicopter.

Before we begin to discuss the aeroplane we must remember that before a modern machine leaves the ground it must be moving at least thirty-five miles an hour with respect to the air. This forcing of the edges of these broad-pitching, curved surfaces through the air at such a velocity naturally drives the air downward and these particles of atmosphere react in exactly the same degree upward, thus forcing the planes and the attached apparatus upward. Therefore, as long as the aeroplane rushes through the air at that or greater speed the thousands of cubic feet of air forced down beneath the wings deliver up a reaction that results in complete support. When an aircraft fails to move at that velocity it loses “flying speed” and falls to the earth. The net result of this reaction is called “lift,” and as long as the machine sweeps forward at that momentum it has lift. The engine, of course, must supply this forward movement, and when it stalls, the heavier-than-air machine must glide to a landing-place or fall perpendicular to the ground.

To understand why a heavier-than-air machine flies it is necessary to remember that air or atmosphere has many of the characteristics of water. Indeed, like the ocean, its pressure varies at different altitudes. At sea-level a cubic foot in dry weather weighs 0.0807 pounds, but at a mile above sea-level it weighs only 0.0619 pounds, and at five miles 0.0309 pounds per cubic foot and so on up. Therefore machines designed to fly at sea-level often fail to get off the ground at 12,000 feet above the sea in such countries as Mexico.

Air also has motion. Its tendency to remain motionless is called inertia, and its characteristic desire to reoccupy its normal amount of space is known as its elasticity, and the tendency of the particles of air to resist separation is described as its viscosity. Thus we see that air has practically the same characteristics as water, only it is much lighter.

Without going into a technical discussion of all the forces that enter into the flight of an aeroplane we must, however, realize that if the pressure of the atmosphere is uniform in all directions, in order to make the air forced under a wing or plane lift more than the air above forces down, the wing of the plane must be curved in such a way that the forward motion of the edge of the wing causes the air underneath to force any particle of the surface upward, while the upper surface is relieved of the pressure. This is done by curving the surface of the planes so that the under surface is concave while the upper part is almost convex, like the outspread wing of a bird. When this wing is forced horizontally through the air it creates a vacuum immediately behind the upper or convex part, the under pressure is still constant and the surface is lifted upward. That is why a plane covered with a curved surface will fly and a plane with a flat surface will not. In short, a curved surface when moving through atmosphere causes eddies in the air, and if the curvature of the wings is properly calculated, it leaves a vacuum near the rear edge of the surface of the plane and it climbs upward. The smaller the angle the smaller the lift or climbing power of the plane. Thus a 15-degree angle will lift one pound; if reduced to 10 degrees it will only lift two-thirds of a pound, but because a wing is curved a plane could fly at several degrees less than 0 degree, but its “stalling” or critical angle beyond which it is not safe to go is 15 degrees.

It must be borne in mind that the larger the wing surface the larger load the aeroplane can carry, for the lift of a heavier-than-air machine depends entirely on the number of square feet of surface in the plane or wings. The larger the planes the more power is required to force them through the air and the less easy they are to manœuvre and land. The Nieuports, Spads, Sopwiths, and Fokkers, with their small wing spread of less than 30 feet, made them much easier to fly, even though they land faster than the “big busses.” Therefore every pound of weight added to an aeroplane decreases its speed proportionately and requires an equivalent increase in horse-power to force it through the air. Of course, an increase of speed gives an increase in lift, so by doubling the speed of a plane you increase the lift just four times.

There are, however, a number of factors which tend to decrease the progress of a machine through the air: the head resistance of the fuselage, the motor, the struts, the wires, the landing-gear, etc. These things do not add to the lift and are described as “dead-head” resistance. Stream-line, or the tapering of all surfaces which resist the air, helps reduce this resistance, so that the design of the plane has much to do with its speed, also as to whether the plane can climb faster than fly straight ahead. Naturally the horse-power of the motor determines the flying speed of the aeroplane as much as any other factor.

To lift a plane off the ground it must be travelling at least 35 miles an hour with respect to the air, as we have pointed out before. So if a gale is blowing 20 miles an hour the aeroplane may be lifted off the ground when moving no faster than 15 miles an hour with respect to the earth. Likewise unless a machine is moving 35 miles an hour it will lose flying speed and fall to the ground.

Machines do not all land at the same speed. The famous Morane monoplane skimmed along the ground at anywhere from 45 to 90 miles an hour. It is manifestly impossible to do more than suggest the fundamental principles of aeroplane flight here. To be sure, the type of aircraft has, as we have indicated, much to do with why and how it flies. Because of its similarity to the bird and owing to the lack of struts, etc., to increase the head resistance the monoplane or single-wing plane is the fastest machine. The absence of struts and the few bracing wires brings a greater strain on the wings and increases its chances of breaking. The biplane, with its two parallel wings separated by struts, is more easily braced and proportionately stronger. The lift is also greater, due to the additional wing surface. The vacuum made over the lower wing is interfered with by the upper plane, and thus neutralizes somewhat the lifting and flying efficiency of the upper wing. Since a plane must reverse all its stresses when looping, the double supports of the biplane make it less susceptible to doubling up and falling. These are some of the reasons for the popularity of the biplane.

The triplane is so called because it has three tiers of wing surfaces set one above the other. This allows for even greater strength in construction, and despite the resistance several very fast-climbing triplanes have been built. The famous Caproni triplanes with three motors have a wing spread of 127 feet. Many biplanes and flying-boats also have approximately 126-foot wing spread. The well-known Handley Page bomber and the NC-1, NC-2, NC-3, NC-4 Naval Flying Boats, which tried the Atlantic flight, had a similar wing spread.

In the war the small aeroplane of the monoplane or biplane type with a small wing spread and equipped with a rotary motor, whose nine or more cylinders revolved with the propeller, or a small V-type motor, was called a scout. These biplanes seldom had a wing spread of over 28 feet and the horse-power of the rotary motors seldom developed more than 150 horse-power, whereas the stationary motors for these same machines generated as much as 300 horse-power, as in the case of the Hispano-Suiza. These machines were used for fighting because they made as high as 150 miles an hour and responded so easily to the slightest movement of the “joy stick” and, consequently, manœuvred so readily. Since trick flying was absolutely essential to air duels these machines were best for this purpose and for quickly getting information of troop movements.

The next larger size, seating two men and driven by the same types of motors or even larger twelve-cylinder Rolls-Royce or Liberty motors, but with a wing spread of from 34 to 48 feet, was used for taking photographs, directing artillery-fire, and general reconnaissance in war. The multimotored machines, with a wing spread of anywhere from 48 to 150 feet, were used for bombing at night or during the day. Owing to the size of these machines and because of their slow-flying speed they were easy to land. Some of the scouts weighed, with petrol and two hours’ fuel, less than 1,000 pounds, whereas the four-motored bombers, with 127-foot wing spread, weighed over six tons and could carry a useful load of three tons.

The hydroaeroplane does not differ fundamentally from the aeroplane as regards flying principles. In structure it may be a biplane or triplane, but owing to the supports necessary to carry the pontoons it cannot be easily attached to a monoplane. Structurally, it differs from the aeroplane only in having pontoons or a boat substituted for wheels and landing chassis. Owing to the surfaces presented by the pontoons or the hull of the boat, looping is practically eliminated and the spread of these flying craft is much slower than land machines.

Although M. Fabre conducted experiments with aeroplanes carrying floats instead of wheels, Mr. Glenn H. Curtiss was the first to successfully construct and fly a hydroplane. At the time of his flight down the Hudson River from Albany to New York he equipped his plane with a light boat to protect himself in case of a forced landing on the water. Encouraged by this experiment under the Alexander Graham Bell Aerial Experiment Association, and by later attaching a canoe, he succeeded in landing and getting off the water. Later he built a hydroaeroplane and flew successfully at San Diego, Cal., thus establishing America as the land which invented and developed the seaplane and flying-boat.

Structurally, the modern seaplane has two small pontoons on the end of each wing and a small boat in the centre, or sometimes only two pontoons in all which are side by side near the fuselage. The flying-boat has one large boat instead of a fuselage, with a small pontoon on the end of each wing. The former is used for fast flying, but owing to the air resistance to the pontoons, and especially to the boats, the speed cannot be compared to that of the scout aeroplanes. Moreover, they are much harder to do stunts with and few are known to have looped the loop. Like the big land bombers the flying-boats may be equipped with as many as three motors. One of these has carried as many as fifty passengers at one time.

Contrary to the accepted notion, these flying-boats are very hard to land on the sea because it is so difficult to calculate the position of the wave when you strike—both are moving so rapidly.

As we have already seen that due to the fact that a heavier-than-air machine must be moving at least 35 miles an hour to get off the ground or water, a strong and powerful motor is absolutely essential to make aeroplane flying possible. We have already discovered that the Wrights had to construct their own motor because none was light enough for an aeroplane. Their 16 horse-power single-cylinder engine weighed over 200 pounds. To-day the Liberty is rated at from 400 to 450 horse-power, and it weighs less than two pounds per horse-power. An Italian aeronautical engine develops 700 horse-power, and one sixteen-cylinder American motor generates 900 horse-power. This shows the tremendous development of the motor for modern flying.

A Shortt “pusher” seaplane equipped with a one-and-a-half-pounder gun.

From a photograph by Bain News Service.

British-built Curtiss flying-boat, at Brighton, England.

But, aside from the matter of weight and horse-power, the aeromotor has been called upon to perform at altitudes of as high as 30,000 feet as efficiently as on the ground. Since the atmospheric pressure at that height weighs a great deal less than at sea-level the flow of gasoline and lubricants is very much decreased, so that the efficiency of the motor may fall off proportionately. To meet these requirements the aviation motor must be especially designed, and since the vibration of the propeller shakes the frail frame on which the engine is mounted, the materials must have the greatest strength and resistance.

Nevertheless, in both types of motor, the rotary air-cooled and the stationary V type, the engineers have succeeded in making engines that would climb still higher than the 30,500 ceiling already made, if the aviators could stand the cold or have enough hydrogen to keep them from fainting.

The motor then is the heart of the heavier-than-air machine, and when it stops the aeroplane must volplane or fall to the earth, a slave to the laws of gravity.

CHAPTER IV

LEARNING TO FLY

EARLY METHODS—DEVELOPMENT OF SCHOOLS—STUDYING STRUCTURE OF PLANES, MOTORS, THEORY OF FLIGHT, AERODYNAMICS, MAP READING—FRENCH SYSTEM—GOSPORT SYSTEM

From the time of the first flight of the Wright brothers in 1903 to the breaking out of the Great War in July, 1914, the art of flying an aeroplane was not taught systematically either in private or military schools, primarily because flying in a heavier-than-air machine was regarded by civilians as a very dangerous sport and by military authorities as hardly more than a dubious scout for locating troop or train movements. For that reason very few civilians were induced to take up aviation except a few of the more daring sportsmen. Consequently, civilian flying on a large scale did not flourish.

It is true, however, that several small schools attached to manufacturing plants did attempt to teach the rudiments of flight and aircraft construction. These schools did not prosper because only a few pupils who wished to give exhibition flights attended, and the art of flying and aircraft development suffered.

In England several schools were started with indifferent success for the same reason as obtained in America, and in France and Germany, aside from a few aviators who were striving for new world’s records, most of the flying training was in the army. Therefore most of the great fliers, like the Wrights, Beachy, Martin, Curtiss, Farman, Bleriot, Garros, Vedrines, Graham-White, Sopwith, A. V. Roe—to mention only a very few—learned to fly themselves. For that reason the toll of lives taken in flying was high. Nevertheless, that did not stop these daring fliers from stunting and exploring all the aerial manœuvres possible with a heavier-than-air machine. As a result Pegout looped the loop; Ruth Law flew at night; Bleriot crossed the channel; Garros the Mediterranean Sea; Vedrines flew from Paris via Constantinople to Cairo; and in July, 1914, Heinrich Oelerich climbed to 26,246 feet altitude in Germany, and in the same month another German flew for twenty-four hours one minute, without stopping.

Meanwhile France had trained several hundred aviators for her army and Germany had five or six hundred trained fliers, including those in the Zeppelin service. The United States army had hardly more than fifty fliers when the Mexican trouble broke out, and only half a dozen aeroplanes to use on the Mexican border.

As soon as the war began and aircraft demonstrated that the side which got control of the air could put out the eyes of the opposing army and that the great struggle might be decided in the air, all the belligerent nations began to train aviators for the war in the air.

France was the first to develop a school of flying, and the French method, with slight variations, was adopted by England and the United States. A description of their method will give a comprehensive conception of the training necessary for a military flier in the war.

Early in the war most of the army, navy, and private aviation schools of the United States adopted the penguin system of learning to fly. That method, invented by the French, consisted of using as a training-machine an aeroplane that had so small a wing spread or so weak a motor that it merely hopped five or six feet off the ground when the motor was wide open. The small wing spread caused it to zigzag along the ground like a drunken man. For those reasons, perhaps, it was named after the penguin, which does not remain long on the ground or in the air and which has an irregular gait.

The first step in learning to fly consists in studying the structure of the aeroplane and of the aeronautical engine, and aerodynamics, or the science of the forces that aid or hinder the flight of heavier-than-air machines. During the last half-dozen years many of the manufacturers of aircraft maintained schools in order to encourage men to learn the art of flying, and have given their pupils the chance to study at first hand the designing, the building, and the assembling of aeroplanes and hydroplanes. That has given the pupils a thorough knowledge of every detail of the aircraft—an invaluable asset to an aviator who has been compelled to make a forced landing far from a repair-shop. In the “ground” schools conducted by the United States Government for instructing aviation officers at the various institutions, like Cornell, Massachusetts Institute of Technology, and Princeton, a great deal of time was devoted to assembling aeroplanes.

Most of the manufacturers of aircraft in this country do not make the motors used to propel their aeroplanes. The aeronautical motor is one of the most difficult machines to build successfully. A motor that runs as smoothly as a watch on the ground may hesitate and sputter at an altitude of a thousand feet, and at three thousand feet may stop altogether. Engineers say that that is because the change in temperature and in atmospheric pressure causes a difference in carburization. All these things the prospective flier had to learn as well as the reasons for the same.

Contrary to the general notion, the construction of the aeronautical motor differs radically from that of the automobile engine. In point of weight the difference is marked. Seldom is any stipulation made that limits the weight of the automobile motor in proportion to the amount of horse-power; a few pounds more or less is not an important consideration in a pleasure-car or a motor-truck. But in an aeroplane every ounce of superfluous weight must be eliminated from the engine, which must nevertheless be strong enough to withstand the most violent strain.

The aeroplane motor is subject to far greater strains than the automobile motor is. Except during a race, one rarely runs the engine of an automobile at its maximum speed; the aeroplane motor, on the contrary, usually runs at full speed from the moment the aeroplane starts until the motor is shut off and begins to volplane down to the earth. It is true that you can regulate the aeroplane engine by the throttle to run from as low as three hundred revolutions a minute to as high as sixteen hundred; but except when testing the motor there is rarely any reason for slowing it up while in the air. The load that the propeller of an aeroplane carries is much less than the load that the shaft of an automobile carries, but, on account of the frail structure of the plane, the vibration is much more violent. A battle plane seldom weighs more than two thousand pounds, and a scouting machine of the Nieuport type tips the scales at not more than one thousand pounds.

For these reasons aircraft require special kinds of motors. The V type is so called because the cylinders are set in the form of that letter; the rotary motor has the cylinders arranged in a circle like the spokes of a wheel, and it revolves on its shaft like the propeller. The rotary motor is used in scouting machines because it is light. The revolving engine also revolves on its shaft, but it has a great many more cylinders arranged side by side like the cylinders of an automobile engine. It is much heavier than the rotary type; it may have as many as thirty-two cylinders.

Of course, a knowledge of the automobile engine was an aid to the prospective aviator; for, except in the process of cooling and the revolution of the cylinders, the principles of the automobile motor and those of the aeroplane are identical.

At aviation schools the pupils went thoroughly into all those things and supplemented their knowledge by continually mounting and dismounting engines and examining their most intricate parts. The schools also kept on hand large aeroplane models, which the students took apart and put together again. In the classroom the prospective aviators studied the mathematics and the theory of aerodynamics. All this work was very important, for an aeroplane is such a nicely balanced machine that if it is not perfectly constructed mathematically it will not fly safely.

For example, if the tail plane or flat, finlike surface that projects from the sides of the tail of the body, or fuselage, has too much “incidence,” or, in other words, is slanted at too sharp an angle downward, it has a tendency in flight to lift the rear of the machine and to make it dive. A seaplane, when properly constructed, is so evenly balanced that, when the crane that lifts it off the mother ship holds it suspended in the air, the machine is equipoised like a bird with wings spread in flight. If the plane is heavier on one side than on the other, it will, while “banking,” or turning a corner, slide toward the centre of the circle; that sometimes causes a “tail spin,” in which the machine whirls round as if it had been caught in a whirlpool. That is a very difficult situation, for an aviator usually ends in a smash at the bottom of the whirlpool unless the pilot has altitude enough to flatten out his plane before it gets too close to the ground. These things were all taught before the novice went up in the air.

Map reading and air navigation were the next studies in military aviation schools. First, the student learned how to judge the height of hills and the size of towns from different altitudes, so that when flying he could tell what part of the country he was passing over. Many of the schools perched the prospective fliers high in the air in a classroom and spread out a miniature landscape made of dirt and sand on a map beneath them so they could get practice in perspective.

Of course, when an aviator is lost in the fog or above the clouds he needs to use all the instruments on board to find his position. For that purpose drift instruments are mounted on aircraft; those tell how much the air-currents, which have the same effect on aircraft as the tide has on a boat, have driven him off his course. A compass indicates the direction in which he is travelling, and other instruments show him whether his machine is climbing, diving, or “banking”; the aneroid barometer indicates the altitude. It is essential, of course, for the aviator to know how to read those instruments correctly. Without the information they give him, he might not know, if flying at night or in a cloud, that his craft was climbing at a dangerous angle until wrenches or other loose implements began to fall out of the machine.

As the next step in the training the student learns the controls. To do that he runs the “taxi” or “lawn-mower,” as the training-machine is called, up and down the field. The “hopping” of this machine familiarizes him with “getting off” and landing, and with the noise of the propeller. After he has learned to steer his machine in a straight line, he takes longer “hops” until he is thoroughly familiar with the “joy stick” which pulls the elevators or ailerons up or down or operates the rudder.

Soon afterward the student went up with an instructor for a long flight. The purpose of the flight was to get the pupil used to higher altitudes and to the motion of the aeroplane, and to give him a chance to watch his teacher actually running the machine. Strange to relate, many who have felt an uncontrollable desire to jump off high buildings have no such feeling while in an aeroplane. That is because they sit and look out horizontally instead of perpendicularly downward, and because they move at such tremendous speed.

After several trips of that kind, the instructor let the student handle the controls until he could climb, dive, and “bank,” or turn the machine in the air. But the pupil was not permitted to land a machine until near the end of his course; for next to getting out of a tail spin, a dive, or a side slip, landing was the hardest task in flying. Statistics show that more aviators have been killed in making landings than in any other way. Many of the accidents, of course, were caused by the nature of the ground, for when the engine of the aeroplane stops, the aviator has to volplane or glide down wherever he can.

One of the difficulties of landing is owing to the fact that even training-machines cannot land at a slower speed than thirty-five miles an hour. If the wheels of the aeroplane, when they first touch ground, do not skim over the surface of the field, the machine is liable to “nose in” and turn a somersault. Indeed, that is why the pusher type of training-machine, with the propeller in the rear of the pilot, is being abandoned for the tractor machine, which has the propeller in front. If an accident does occur with a tractor the engine does not “climb your back.” One of the greatest dangers of flying a seaplane is due to the fact that the engine is installed not in the hull but high above the aviators’ heads, upon which it is apt to fall in case of a crash.

The student was next permitted to fly alone. Most machines were so strongly built that accidents were seldom caused by breakage, although, of course, before each flight the aviator and his mechanic critically examined his machine for broken parts. With a reasonable amount of care straight flying by daylight was comparatively safe.

In the French aviation schools, before the military birdman could pass his final examinations, he had to climb twice to an altitude of six thousand feet and spend an hour at a ten-thousand-foot altitude. If he passed that test successfully, he had to fly over a triangular course of one hundred and fifty miles and land at each corner of the triangle.

Before he could fly his machine on the battle-front the French flier had to know how to loop, to fall or dive at such a steep angle that his machine actually dropped through the air for several hundred feet before it flattened out—a tremendous strain on the wings of a machine—to side slip or round a curve with his machine banked at such an angle that it gradually slid toward the centre of the circle, to climb or tail dive at such a pitch that the aircraft actually slips backward tail foremost. Indeed, in the last days of training the student was encouraged to practise all kinds of stunts and tricks, for when an enemy descended on you from the clouds above and was sitting on your tail weaving a wreath of bullets from a machine-gun round you, your only chance of escape was by means of a loop, a dive, a side slip, or a roll.

Another interesting test a pilot had to undergo before he got his license to do battle was to ascend fifteen hundred feet, cut off all power, and volplane down in a spiral to a fixed point. To perform the manœuvre successfully required great skill. All the members of the famous Lafayette Escadrille had to undergo those tests before becoming fighting aviators, and Americans who received their final training in France had to go through the same training.

In our government flying-schools at Mineola in Long Island and the other flying-fields in Texas and other parts of the country, at San Diego in California, the students were put to similar tests of skill. In the private civilian schools, however, instructors rarely attempt to teach their pupils more than straight flying. But most aviators agree that every flyer ought to know the “stunts” in order to meet successfully any extraordinary situation that may confront him.

Of course the training for aerial observers, wireless operators, and photographers was very different from that of the pilots. In each case the instruction was peculiar to the science they were to practise, and it had little to do with aviation, only in so far as it was actually affected by flying. The men who took the pictures had to make a study of the science of photography. The same was true of the wireless operator. The observer, however, had to study topography and the use of the machine-gun, and target practice such as characterized the work of the pilot. In different countries this differed with the methods developed there. In England the pilot often shot at toy balloons in the air while chasing them with his machine or at targets on the ground. The same method was employed by the United States. Nearly all the great aces in the war were very clever shots, and Major Bishop attributed most of his success to his skill with the machine-gun.

Finally the Gosport system of training aviators was adopted by the British and the American armies because it permitted the training of tens of thousands of fliers at the same time. The principles taught were the same as those enumerated above. The system, however, reduces the time spent on each operation to the minimum, specifying the number of hours to be spent on each step in the course. Here is a sample of the outline of the training under that system:

STANDARD OF TRAINING

Part 1. Pilots—Flying Wings

1. Ground Instruction.

• 1. Buzzing and Panneau
• 2. Artillery Observation
• 3. Gunnery
• 4. Aerial Navigation
• 5. Engine Running
• 6. Photography
• 7. Bombing and Camera Obscura
• 8. Air Force Knowledge
• 9. Engines and Rigging, Workshops Course
• 10. Drill and P. T.

2. Air Tests.

• 1. Flying Instruction
• 2. Formation Flying
• 3. Cross Country
• 4. Reconnaissance
• 5. Photography
• 6. Bombing (Camera Obscura)
• 7. Ring Sights and Camera Gun
• 8. Altitude Test and Cloud Flying
• 9. Aerial Navigation

3. Appendices.

• A Flying Instruction
• B Formation Flying
• C Cross Country
• D Bombing
• E Wireless
• F Gunnery
• G Ring Sights and Camera Gun
• H Aerial Navigation
• I Photography

To insure a certain amount of continuous practice the following minimum times will be spent on ground subjects. It must be realized, however, that efficiency, and not time spent, is the ultimate passing standard.

Lectures will be given covering—

(1) All questions on above subjects.

(2) Practical wireless covering knowledge useful to a pilot.

(3) All ground signals as given on new Artillery Observation card, 40-W.O.-2584.

Thus every step in the education of the flier was provided for and thus the United States turned out over 10,000 aviators.

CHAPTER V

AEROPLANE DEVELOPMENT, 1903 TO 1918

ADER’S EXPERIMENTS—MAXIM’S MULTIPLANE—DUMONT’S AEROPLANE—WRIGHTS’ 1908 PLANE—VOISIN PUSHER—BLERIOT’S MONOPLANE—AVRO TRIPLANE—FARMAN’S AILERONS—OTHER TYPES

Although the Wright brothers made their first flight in a heavier-than-air machine in December, 1903, it was not until September 15, 1904, that Orville Wright, flying the Wright biplane, succeeded in making the first turn, September 25 before they made the first circle, and October 4, 1905, before they managed to stay in the air for over half an hour. Moreover, it was not until 1908 that they made their first public flights.

Long before the Wrights first flew at Kitty Hawk military men realized the value of observation from the air, and balloons attached to cables had been used for that purpose in the Franco-Prussian and Boer wars for discovering the movement and disposition of troops. Clement Ader, however, was the first to succeed in securing an appropriation for the construction of a heavier-than-air machine which was to fly in any direction like a bird. In 1890 he induced the French Government to appropriate $100,000 for the construction of such an engine. After many experiments his machine failed to get off the ground, and in 1897, after seven years of hard work, the French Government refused to appropriate any more money.

In 1905, however, as soon as the same government heard of the sustained manœuvred flight of 33 minutes, 17 seconds, done by the Wrights, they negotiated for the acquisition of the machine, provided it could attain a height of 3,000 feet. But at that time the Wrights had not flown over three hundred feet, nor risen above one hundred feet, and could not promise to fill the French requirements.

The British Government had also given Sir Hiram Maxim an appropriation for constructing a flying-machine about the same time that the French Government was financing Ader. Maxim built one of the multiplane type, measuring 120 feet, equipped with two steam-engines of 170 horse-power and weighing 7,000 pounds, but like Ader’s experiment it never got off the ground.

We have already noted the appropriations made by the United States Government to Samuel P. Langley for his aerodrome. It was the United States Government, upon the recommendation of President Theodore Roosevelt, which first ordered a military aeroplane in December, 1907, giving definite specifications for the same. The machine was required to carry two persons weighing 350 pounds and fuel enough for a 125-mile flight, with a speed of at least 40 miles per hour.

The Wrights were the only persons to submit bids and they delivered a machine which Orville Wright flew at Fort Myer in September, 1908, making a new record of one hour, fourteen minutes, twenty seconds. An accident prevented the fulfilling of the two-passenger-carrying requirement. In August, 1909, however, the Wright biplane, with a wing spread of 40 feet and equipped with a 25 horse-power engine, flew one hour and twenty-three minutes with Lieutenant Frank P. Lahm as a passenger.

The success of the Wrights naturally stimulated the French, Alberto Santos-Dumont, the Brazilian, who had experimented successfully with lighter-than-air craft, first circling the Eiffel Tower, while Louis Bleriot, the Voisin brothers, Captain Louis Ferber, Henry Farman, Leon brothers, Delagrange, and others began to experiment with aeroplanes.

In 1906 Santos-Dumont flew 700 feet in an aeroplane in one sustained flight and in 1908 the Wrights visited France and gave public demonstration flights at Pau and other places. Their machine was a biplane driven by a small four-cylinder water-cooled engine and two large propellers. These were both actuated by chains gearing on the engine-shaft, one chain being crossed so as to make its propeller revolve in the direction opposite to the other, thus giving proper balance to the driving force. Alongside the engine and slightly in front of it was the pilot’s seat, and there was also a seat for a passenger in between, exactly in the centre, so that the added weight would not alter the balance.

Unlike present-day aeroplanes, this machine had no horizontal tail behind the main planes, and so it was called the “tail-first” type, or “Canard” or “duck,” owing to its long projection forward which resembled the neck of that bird. This type did not steer easily and was abandoned.

The 1908 Wright Plane

The Wright machine had vertical rudders aft, and relied on the two big elevator planes forward for its up and down steering. Its lateral, or rolling, movements were controlled by warping or twisting the wings so that while the angle of the wings on one side was increased and gave more lift, the angle on the other side decreased and gave less lift, thus enabling the pilot to right the machine. The elevators were controlled by means of a lever on the left-hand side of the pilot, the warp by a lever on his right, while by waggling the jointed top of the right-hand lever he also controlled the rudder. This complicated system of control was very difficult to master.

In 1910 the Wrights attached a horizontal tail at right angles to their rudder, and in 1911 they dropped the front elevators entirely. When the United States entered the war, Orville Wright, as engineer for the Dayton-Wright Company, supervised the building of the famous DH4’s, making several thousands of them for shipment to France.

Unlike many machines that followed, the Wright 1908 was launched from a carriage which ran on a rail until the planes were lifted into the air, leaving the carriage on the ground. This same principle was used for launching planes from battleships, although it is now abandoned.

Meanwhile Charles and Gabriel Voisin had successfully developed their machine. On March 21, 1909, Mr. Farman flew a little over a mile at Issy, near Paris, successfully turning, and on May 30 Leon Delagrange covered eight miles at Rome, and finally on September 21 he flew forty-one miles without stopping at Issy.

This Voisin biplane differed from the Wrights’ in that it followed the box-kite principle. It had a box-kite tail to which the rudders were mounted, while the wings had vertical partitions and the plane had no lateral controls, with the result that it could not fly in any kind of a wind without coming to grief. The first machine had a 50 horse-power Antoinette engine and the latter ones a 40 horse-power Vivinus—an ordinary automobile engine, heavy but reliable.

In 1909 the famous Gnome rotary engine appeared. It had 11 cylinders set like the spokes of a wheel; one was fitted to a Voisin biplane by M. Louis Paulhan. There were several innovations on this machine. The under-carriage and tail-booms and much of the understructure was made of steel tubing. Its greatest contribution to the modern aeroplane was the steering-wheel. This was operated by a rod or joy stick, which ran from the front elevator to a wheel in front of the pilot which was pushed forward to force the nose of the machine down, and pulled back to force it up. This made steering much easier. The rudders were worked by wires leading to a pivoted bar on which the pilot’s feet rested. Pushing the right foot steered to the right, pushing the left foot steered to the left—which was also a very natural motion. This method of construction has been maintained to this day on all machines. The Voisin was the first “pusher” type of machine with single propeller in the rear of the engine and the plane. The Voisin was always heavy, but in 1915 it was built in large numbers for bombing purposes because the forward nacelle or nest which held the observer and gunner afforded such an unobstructed range of vision for the observer.

To M. Louis Bleriot goes the honor of first constructing monoplanes and of putting the engine in the nose of the machine with a tractor screw in front of it. He also first designed the fish-shaped, or stream-line, body, with the tail and elevator planes horizontally and the vertical rudder fixed at the rear end of the fuselage. This was the first successful tractor aeroplane with the propeller in front.

In 1909 M. Bleriot came to the fore with his type X1 machine, the prototype of all successful monoplanes. In this he incorporated the Wright idea of warping the wings to give lateral control, and so produced the first monoplane to be controllable in all directions. With this type of machine, equipped with a 28 horse-power three-cylinder Anzani air-cooled engine, M. Bleriot himself flew over the Channel on July 25, 1909. His type X1 model, with a few structural details, was the first to loop the loop regularly in 1912. After 1909, when fitted with Gnome or Le Rhone rotary engines, the performance of the machine was greatly improved. Since the Bleriot under-carriage, excellent for its purpose, could not be made so as to be pushed rapidly through the air, it was abandoned.

M. Bleriot introduced the stick form of control, so that by moving the control stick forward or backward the nose of the machine moved down or up. Pushing the stick to the right forced the right wing down, moving it to the left pushed the left wing down. The rudder was worked by the feet as in the Voisin. Thus a natural movement was given to all the controls and a great step forward was made.

The 1909 and 1910 Avro

Meanwhile in England Aylwin Verdon Roe was experimenting under strictly limited conditions. In 1908 he had got off the ground in a Canard-type biplane, and in the fall of that year he built a tractor biplane, and in the summer of the next year he had it completed. His engine was a 9 horse-power J. A. P. motorcycle engine, the lowest power which has ever flown an aeroplane. It was also the first successful triplane.

In general lines and plan the machine is the prototype of the modern tractor biplanes and triplanes; it had warping wings, tail elevators, and a rudder astern, while the control was by rudder and stick, similar to the Bleriot.

This little machine was further developed in 1909 and 1910. Later Mr. Roe abandoned the triplane for the biplane, which he fitted with a Green engine of the vertical-cylinder type, which was the first of its kind installed in an aeroplane. Thereafter the triplane practically disappeared till it was revived by Glenn Curtiss, as well as British, French, and German designers during the war.

They are great climbers and attain great speed in flying. The small 1910 Avro, equipped with a V water-cooled engine, was the forerunner of the single-seated fighters of the last days of the war.

Because of its fast-climbing ability the 80 horse-power Avro and the Sopwith Snipe were used for the defense of such cities as London and Paris against Zeps and aeroplanes. The large two-seater Avro, with only an 80 horse-power Gnome, flew over 80 miles an hour. As a war-machine early in the conflict it did excellent work bombing. Later, with slightly higher power, it was a very good training-machine. Among two-seated biplanes it marked as great an advance as did the Sopwith Tabloid. Among single-seaters, for the reason that it had been carefully lightened without loss of strength and all details for stream-line had been observed, the same is true.

The Farman Brothers’ Plane

While M. Bleriot was developing his monoplanes, Henry Farman left the Voisin brothers and began experimenting on his own account. The result of his experiments was first seen at the Great Rheims meeting when his Gnome-engine biplane appeared, and on November 9, 1909, he made a new world record of 145 miles in four hours, eighteen minutes, forty-five seconds! Like the Wrights’, his machine had a front elevator stuck out forward, but the vertical partitions had disappeared from the wings, though retained in the tail. The whole machine was built of wood, so that it was very much lighter than the Voisin. Its most remarkable step forward, however, was the use of balancing flappers, usually called ailerons, fitted into the rear edge of each wing. These ailerons were pulled down on one side to give that side extra lift when the machine tilted down on that side. Thus the ailerons had the same effect as warping the wings, and as it then became unnecessary to twist the wing itself, it became possible to build the whole wing structure as a fixed box-girder structure of wood and wire. This was lighter and stronger than was safe with a warping wing. For this reason aileron control is used on all aeroplanes of to-day.

The Farman biplane was fitted with the stick control used by M. Bleriot, the stick working wires fore and aft for the elevator and lateral for the ailerons. A rudder-bar for the feet operated the rudder wires. This was the beginning of the present-day idea of the pusher biplane.

In 1911 Farman abandoned the front elevator and used only the elevator control that was used by monoplanes, and he put the pilot and observer out in front of the machine so that the range of vision was entirely uninterrupted. Later this was covered and called a nacelle or nest by the French. Here the machine-gun was mounted in the days of the World War.

In 1912 Maurice Farman, a brother of Henry, built a machine independent of his brother. He constructed a deep nacelle, giving greater comfort to the pilot. It had a forward rudder, and because long horns supported the rudder, it was called the mechanical cow. When this front elevator was abolished later, it was known as the “Shorthorn.” This was the prototype of the “gun busses” and early war training-machines in England.

In 1913 Henry Farman’s pusher design began to take on its ultimate form. The whole machine was more compact. The nacelle sheltered the pilot better, and the machine did not look as detached from tail and elevator as formerly. The general effect was more workmanlike and less flattened out. This type was ultimately combined with the “Shorthorn” by Maurice Farman into a machine nicknamed the Horace, a combination of Henry and Maurice. In 1917 it was used as a means of training and aerial travel rather than as a fighting-machine.

The 1909 Antoinette Monoplane

The Antoinette monoplane was evolved from the early experiments of MM. Gastambide and Mangin, and designed by the famous M. Levavasseur, the engine as well as the aeroplane. This is the plane in which Herbert Latham failed to cross the English Channel by only a few hundred yards. At the Rheims meeting in August, 1909, it was in full working order, and during the last few days of the meet there was a continual fight for the distance and duration records between Latham of the Antoinette, Henry Farman of the Farman, and Paulhan of the Voisin. The Antoinette was much the fastest, but its engine always failed to hold out long enough to beat the others. However, the Antoinette proved in other respects to be the fastest flying-machine of the year.

It was the first machine in which real care was taken to gain a correct stream-line form. The wings were king-post girders. The body was largely a box-girder composed of three-ply wood. The tail was separated from the rest of the plane by uncovered longerons.

Unfortunately, the internal structure of later machines of this type was weak, so that there were many fatal results from breaking in the air. The control was also very hard to learn. One wheel worked the warping of the wings, another worked the elevator, and there was a rudder-bar for the feet. In spite of this the plane was very beautiful to look at.

The 1910 Breguet

The first successful machine of this type was designed by M. Breguet, a French engineer, who had begun experimenting in 1908, and it appeared the latter part of 1910. The first of the year he produced a machine which was nicknamed the “coffee-pot,” because it was enclosed entirely in aluminum. This was developed later into a bombing-machine which had many interesting features. It was almost entirely constructed of steel tubes covered with aluminum plates, which led some to call it an armored aeroplane, which it was not. The tail, which was one piece with the rudder, was carried on a huge universal joint at the tip of the body, so that it swivelled up or down or sideways in response to the controls. The wings had one huge steel tubular spar, and as a result only one row of interplane struts.

The under-carriage had a shock-absorber of a pneumatic-spring construction, which was highly satisfactory, and was the prototype of the elastic-rubber devices.

The machine was heavy, but it was fast and a great weight-carrier. Because of minor defects in detail the machine never was generally used, but it was the first step toward the big tractor biplane of to-day. The Breguet 1913 seaplane, equipped with a Salmson engine, 200 horse-power, was one of the first to utilize large horse-power and was thus the forerunner of the huge flying-boat of to-day.

The Nieuport

In 1911 the brothers Charles and Edouard de Nieuport produced the monoplane more commonly known as the Nieuport. The fuselage was a very thick body, tapering well to rear. The pilot and passenger sat close together, with only their heads and shoulders visible above the fuselage. All unnecessary obstruction was removed to reduce head resistance. The under-carriage consisted only of three V’s of steel tube, of stream-line section, connected to a single longitudinal skid, thus diminishing it to a noteworthy degree.

This made a very fast machine. With only a seven-cylinder, 50 horse-power Gnome engine it travelled 70 miles an hour, and with a fourteen-cylinder, double-row, 50 horse-power Gnome, rated at 100 horse-power but actually developing 70 horse-power, it reached between 80 and 90 miles an hour. M. Weyman, in the James Gordon Bennett race in the Isle of Sheppey, made an average speed of 79.5 miles an hour, so that allowing for the corners, he must have done around 90 miles an hour on straights.

The fast modern tractor biplanes show the influence of the flat stream-lined, all-inclusive body of the Nieuport.

The most remarkable of the small machines of 1916 was the Nieuport biplane, with the 90 horse-power engine and later the 110 horse-power Le Rhone engine. This was similar to the German Fokker, an excellent fighting-machine, and a direct successor of the Sopwith Tabloid. It was noteworthy for the odd V formed by the struts between the wings.

The 1912 B. E. (British Experimental)

In 1912 the British Government, realizing the importance of the aeroplane as a war-machine for scouting purposes, established the Royal Aircraft Factory at Farnborough, with Geoffrey de Havilland, one of the early British experimenters, as designer. Machines of his invention have been called D. H.’s. His 1912 aeroplane contains some of the ideas embodied in the Avro, Breguet, and the Nieuport. The machine had the lightness of a Nieuport, the stream-line of a Breguet, and the stability of an Avro. It was very light for its size and capacity, and with a 70 horse-power Renault engine it attained a speed of about 70 miles an hour, and it responded in the air and on the ground in a manner never before attained. It was the prototype of a long line of Royal Aircraft Factory designs, through all the range of B. E.’s on to the R. E. series and the S. E. series.

The initials B. E. originally stood for Bleriot Experimental, as M. Bleriot was officially credited with having originated the tractor-type aeroplane. Later B. E. was understood to indicate British Experimental. The subsequent development into R. E. indicated Reconnaissance Experimental, these being large biplanes with water-cooled engines and more tank capacity, intended for long-distance flights. S. E. indicates Scouting Experimental, the idea being that fast single-seaters would be used for scouting. They were, however, only used for fighting.

Another R. A. F. series is the F. E. or large pusher biplane, descended from the Henry Farman. The initials stood originally for Farman Experimental, but now stand for Fighting Experimental, the type being variants of the Vickers Gun Bus.

The 1914 B. E. 2c

Just before the war broke out the British R. A. F. produced an uncapsizable biplane nicknamed “Stability Jane.” Officially she was known as the B. E. 2c and was another type of Mr. De Havilland’s original B. E. Once it was in the air the machine flew itself and the pilot had only to keep it on its course. It was so slow in speed and manœuvring that it was called the “suicide bus,” yet the type was useful for certain purposes.

The 1912 Deperdussin

A very small monoplane, designed by MM. Bechereau and Koolhoven for the Deperdussin firm to compete in the James Gordon Bennett race at Rheims, proved to be the fastest machine built to the close of 1912. It was a tiny plane with a fourteen-cylinder, 100 horse-power Gnome engine. It covered 126½ miles in an hour—the first time a man had ever travelled faster than two miles a minute for a whole hour—and won the race. Allowing for corners, it must have flown well over 130 miles an hour on the straight course.

The little machine was stream-lined, even to the extent of placing a stream-lined support behind the pilot’s head. Two wheels, an axle, and four carefully stream-lined struts made up the under-carriage. The plane was remarkable for having its fuselage built wholly of three-ply wood, built on a mould without any bracing inside. It was the prototype of all the very high-speed machines of to-day. In 1916-17 the three-ply fuselage was adopted in all German fighting-machines and this country is gradually appreciating the improvement and has made many fuselages of three-ply wood.

The 1912 Curtiss Flying-Boat

But perhaps the most remarkable achievement of 1912 was the Curtiss flying-boat. Glenn Curtiss, who won the James Gordon Bennett race in 1909, had succeeded in rising from the water in 1911 with a similar biplane fitted with a central pontoon float instead of a wheeled under-carriage. This he made into a genuine flying-boat, consisting of a proper hydroplane-boat, with wings and engine superimposed. All the great modern flying-boats have descended from this, and it is the forerunner of the great passenger-carrying seaplanes of the future. Curtiss is also credited with the invention of ailerons.

The 1912 Short Seaplane

Another type of seaplane was also developed in 1912 when, after many trials, the Short brothers, of Eastchurch, England, built a successful seagoing biplane, equipped with twin floats instead of the ordinary landing-gear. This, with only an 80 horse-power Gnome engine, was the first flying-machine to arise from or alight on any kind of sea.

The 1912 Taube

The German Taube was yet another development of 1912. This plane is so called because the wings are swept back and curved up at the tips like those of a dove. The builders were Herr Wels and Herr Etrich, of Austria, in 1908. Herr Etrich took the design to Germany, where it was adopted by Herr Rumpler.

This machine was designed to be inherently stable, that is, uncapsizable, and it was successful to a great degree. If it had altitude enough it generally succeeded when falling in recovering its proper position before striking the ground. Other builders had striven for inherent stability, but had failed to get beyond a certain point. Owing to the greater financial support obtainable in Germany the 1912 type Taube lasted, with small changes, far into 1915, when it was succeeded by the large German biplanes, which had greater speed and carrying power. Several machines in Britain and the United States have attained a considerable reputation as having inherent stability.

The 1913 Sopwith Tabloid

T. O. M. Sopwith, Harry G. Hawker, the Australian pilot who first went to Newfoundland to fly the Atlantic, and Mr. Sigrist, Mr. Sopwith’s chief engineer, turned out early in 1913 an extremely small tractor biplane, equipped with an 80 horse-power Gnome engine, which surprised the aeronautical world by doing a top speed of 95 miles per hour and a climb of 15,000 feet in ten minutes, while it could fly as slowly as 45 miles per hour. It was achieved by skilfully reducing the weight, paying close attention to the designing of the wings, and by carefully stream-lining external parts. All the modern high-speed fighting-biplanes, such as the “Camels,” “Snipes,” “Kittens,” “Bullets,” “Hawks,” and others, are descended from the original “Tabloid,” so called because it had so many good points concentrated in it. Because of its fast-climbing ability it was used for the defense of such cities as London and Paris against the Zeps and aeroplanes.

The 1914 Vickers Gun Bus

The first genuine gun-carrying biplane, designed and built by Vickers, London, came early in 1914. Clearly of Farman inspiration, it had an especially strong nacelle to stand the working of a heavy gun. Equipped with a 100 horse-power Gnome engine it made over 70 miles an hour. It was known everywhere as the “Gun Bus,” and the name stuck to the whole class.

The 1914 German Albatross Biplane

Meanwhile the Germans were busy developing machines, so that another development of 1914 was the Albatross tractor biplane, with a six-cylinder vertical water-cooled Mercedes engine of 100 horse-power. This engine was the ancestor of the Liberty engine and of all the big German tractor biplanes. The plane resembled the French Breguets and British Avros of 1910.

The 1915 Twin Caudron

The first aeroplane to fly with consistent success equipped with more than one engine was the twin-motored Caudron, with two 110 horse-power Le Rhone engines. Various other similar experiments had been made and some machines were designed which afterward made good. The French twin Caudron, however, may claim to be the first twin-engined aeroplane. The engines were placed one on each side of the fuselage but inaccessible to the pilot.

The huge four-motored Handley Page bomber.

This machine carried 40 passengers at one time over London and has flown from London, via Cairo and Bagdad, to India. It has a wing spread of 126 feet.

The 1916 Twin Handley Page

In 1916 the British Handley Page machine with 100-foot wing spread, driven by two Rolls-Royce motors of 250 horse-power, performed many remarkable bomb-carrying feats for long distance. A later machine, with 127-foot wing spread and four engines, flew via Cairo and Bagdad to Delhi, India, and still another carried a piano over the Channel. A large fleet of these bombers were ready to attack Berlin when the armistice was signed.

The 1917 Spad

The Spad was designed by M. Bechereau, of Deperdussin fame. It and the Albatross D3 model were both descended from the Deperdussin, the Nieuport, and the Tabloid. The Spad superseded the Nieuport as a fighting scout on the West Front because of its superior speed when driven by a Salmson engine.

The 1917 D. H. 4

The 1917 D. H. 4 was designed by De Havilland, and the S. E. 5 was built by his successors at the Royal Aircraft Factory. Both were descendants of the B. E., as is the Bristol Fighter, built by the British and Colonial Aeroplane Company, of British, and designed by Captain Barnwell.

The German Gotha, which bombed London so often, was a descendant of the Caudron and the Handley Page twin-engine planes.

In 1917 Italy produced her famous three-engined Caproni triplane, driven by three Fiat 1,000 horse-power engines. It had 150-foot wing spread and was used for bombing purposes. S. I. A. and Pomilio were smaller fighting-machines, equipped with Fiat engines. All of these machines were exhibited in the United States and many Caproni triplanes were built in this country.

CHAPTER VI

DEVELOPMENT OF THE AEROPLANE FOR WAR PURPOSES

GERMAN AERIAL PREPAREDNESS—PRIZES GIVEN FOR AERONAUTICS BY VARIOUS GOVERNMENTS—FIRST USE OF PLANES IN WAR—FIRST AIRCRAFT ARMAMENT

There is no gainsaying the fact that Germany, in her eagerness to develop every engine of war further than any other nation, so that when “Der Tag” came she would be mechanically superior and thus able to quickly crush any adversary, instantly saw the advantage that control of the air would give her.

For that reason, as soon as the Wrights began to demonstrate in France, in 1908, the feasibility of the aeroplane as a scout, the Germans realized the importance of the aeroplane as an adjunct of the dirigible, whose development they had already been committed to since 1900, when Count Ferdinand Zeppelin built his first rigid lighter-than-air craft. Since aeronautic motors had to be used on both types of aircraft, and since the speed and flying radius depended on the efficiency of the engine, the Germans set about to develop them.

The French War Department had in 1910 laid down rules and regulations for a competition to develop aeronautics. They specified that the aeroplane and engine should be made in France, and that the distance of flight must at least be 186 miles, carrying 660 pounds of useful load, or three passengers, and to attain an altitude of 1,640 feet. The sum of 100,000 francs was to be paid for the machine which accomplished this feat, and 20 other machines of the same type were to be bought for 40,000 francs each. In the lists of that year 34 aeroplanes of as many designs were built, but only 8 passed the tests. Weyman’s Nieuport with a Gnome engine attained an average speed of 116 miles an hour.

As a result of this contest England, Germany, and Austria established aeroplane meets for 1912. England offered 10,000 pounds in prizes. Prince Henry of Prussia urged the German Government to appropriate $7,000,000 for military aeronautics. On January 27, 1912, the Kaiser offered 50,000 marks in prizes to develop aeromotors. The Aerial League of Germany started a public subscription which brought in 7,234,506 marks. The purpose of the league was to train a large number of pilots for a reserve and to encourage general development of aeronautics in Germany.

This proved to be a great success, for by the end of 1913, 370 additional German pilots had been trained, making a total of over 600. Meanwhile, German constructors increased from 20 to 50 in the same period of time.

The development of aeronautics under the auspices of the Aerial League induced the Reichstag to appropriate $35,000,000 to be expended during the next five years for military aeronautics. This was by far the most liberal appropriation made for war aeronautics by any government in Europe.

Under this encouragement, by the middle of July, 1914, the German aviators broke all the world’s records, making a total of over 100 new records of all kinds. The non-stop endurance record of 24 hours, 12 minutes was made by Reinhold Boehm, and Heinrich Oelrich attained a new ceiling at 26,246 feet. Herr Landsman covered 1,335 miles in one day, making the world’s record for distance covered by one man in one day. Roland Garros held the world’s record of 19,200 feet before Otto Linnekogel made 21,654.

The stream-lining of aircraft and the development of the Mercedes and Benz gasoline motors under the incentive to win the Kaiser’s prize was the big factor in this aeronautic progress. Not only did the Germans make new aviation records, but they also won the Grand Prix race in Paris, 1913, with engines the details of which were most jealously guarded, defeating the best English and French machines. Indeed, the Mercedes motor used on Zeppelin, aeroplane, and automobile was the same in fundamentals.

To Americans who are familiar with the difficulties we experienced in the early days of our entrance into the World War in getting quantity production with the Liberty motor, it is evident from the fact that the Germans had three large factories filled with tools, dies, gigs, etc., for quantity production of the Benz, Mercedes, and Maybach engines, that Germany believed that she had control of the air in June, 1914. She had already broken all the world’s records in road-racing, as well as in the air, and she had more than a score of Zeppelins and over 500 standardized planes.

Naturally, the preparations of the Germans did not fail to attract attention in France. Races and aeronautic contests at military manœuvres, besides aero expositions, were held by the French, and the success of the Paris-Madrid and Paris-Rome race in 1911 influenced the French Chamber of Deputies to appropriate 11,000,000 francs for military aviation. The Kaiser’s prize and Prince Henry of Prussia’s recommendation of $7,500,000 appropriation for German aviation caused the Paris Matin to start a national subscription by donating 50,000 francs for an aeronautic fund similar to that subscribed by Germany.

In 1911 Mr. Robert J. Collier loaned his aeroplane to the United States Government to be used for scout duty on the Mexican frontier.

In February, 1912, during the Italian-Turkish War, the Italians used one aeroplane for locating the position of the Arabs, and several bombs were dropped without any attempt to do any more than guess at the place where they would land. As a matter of fact, they fell far from their objectives, and served no military purpose further than to frighten the horses. In locating the distribution of troops, however, this aeroplane was most valuable.

For that reason many military men even thought that the aeroplane, because of the velocity at which it moved, could not be of much value other than for scouting, and as no guns had been successfully mounted on aircraft before the World War, the aeroplane was not regarded as an offensive weapon. Indeed, that was one of the developments of the war.

The first attempts to mount a machine-gun on an aeroplane were made in France on a Morane monoplane. In order to shoot over the propeller a steel scaffolding was erected, and the pilot was supposed to stand up to sight his gun. This was impracticable, and the structure retarded the vision of the pilot and the speed of the aeroplane.

In the early days of the war pilots seldom flew over 3,000 feet high, and since there were no machine-guns mounted in a practical way, the pilots could only content themselves with firing revolvers at one another. The only thing they had to fear was rifle-shot and the trajectory of artillery. The few antiaircraft guns had no greater range than 3,000 feet, and, as a matter of fact, most of the reconnaissance work done at Verdun in the first six months of 1916 was at 3,000 feet altitude.

The first historic record of a machine-gun mounted on an aeroplane was in the despatch telling of the death of the French aviator Garaix on August 15, 1914, by the aerobus Paul Schmitt. Garaix had 200 rounds of ammunition. In December of that year the 160 horse-power Breguet piloted by Moineau mounted a machine-gun. The French pusher Voisins, with no obstruction of vision to the gunner in the nacelle, afforded an excellent opportunity for the use of machine-guns. Moreover, most of the aeroplanes brought down in the early days of the war were the victims of engine trouble or shots from rifles on the ground. A staff report of October 5, 1914, of the Germans relates that the French aviator Frantz, flying a Voisin with his mechanic Quenault, shot down a German Aviatic plane with two aviators from 1,500 metres altitude, killing the two Germans. For this feat Sergeant Frantz received the Military Medal, the first decoration given a French flier in the war.

On October 7 Captain Blaise and Sergeant Gaubert, in a Maurice Farman, with a rifle shot down Lieutenant Finger, a Boche who had defended himself with a revolver. Captain Blaise expended eight shots before he got the German flier.

The first recorded equipment of a machine-gun on a German machine was on October 25, 1914, when a Taube near Amiens opened fire on a Henry Farman machine piloted by Corporal Strebick and his mechanic, who were directing artillery-fire. The Germans first used a Mauser gun for their aeroplanes.

Meanwhile, the need for having a machine-gun fixed stationary on the aircraft and armed by manœuvring the aeroplane became more evident. Roland Garros, who was the first to fly across the Mediterranean Sea from France to Tunis, Africa, mounted a gun to shoot through the propeller on February 1, 1915. In order to protect the blades from the bullets, he had the propeller-tip covered with steel. Thus, when the bullets hit, they were deflected. Only 7 per cent hit the blades, however.

This was a crude way of mounting the gun, and it was Garros’s mechanician who worked out the method of gearing up the machine-gun so that it shot its 600 bullets between the revolutions of the propeller. This enabled the so-called single-seater scout tractors, with propeller in front, to fly armed with a machine-gun mounted over the hood of the engine, directly in front of the aviator. It was also the beginning of the use of the aeroplane as a fighter in aerial duels and in contact patrol of later days when it descended to attack troops in the trenches and trains on the tracks.

January 1, 1915, was the date of mounting the first Lewis machine-gun on a Nieuport aeroplane to shoot over the propeller. The Germans copied this with their Parabellum light gun, but it was not till July, 1915, that the German Fokker first appeared with a synchronized machine-gun mounted on it. Since a propeller revolves 1,400 times a minute, a blade passes the nose of the gun 2,800 times a minute, and the machine-guns were geared to shoot about 400 shots a minute, so that one shot passes through to every seven strokes of the propeller-blade. Sometimes, however, as many as two guns were synchronized to shoot through the same propeller. A push-button on the steering-bar fires the gun while the pilot keeps his eye on the enemy through the telescope in front of him.

The Lewis gun is an air-cooled, gas-operated, magazine-fed gun, weighing 26 pounds with the jacket and 18 pounds without. The facility with which the gun can be manœuvred into any position or angle makes it a very efficient aeroplane gun. The ability of this gun to function automatically, and the speed with which it operates, is due to the use of a detachable drum-shaped, rotating magazine which holds 47 or 97 cartridges each. When the magazine is placed in position it needs no more attention until all the cartridges are empty, when the magazine is snatched off and another is stuck on. This gun is the invention of Colonel Isaac Lewis, a retired American army officer.

The Vickers is an English gun, belt-fed, water-cooled, recoil-operated. It can shoot from 300 to 500 shots a minute. Since all the shells are in a belt it can be fired continuously until the 500 shots have been used up. Its water-cooled devices were dispensed with on the aeroplanes.

The German Maxim is similar to the Vickers. The Lewis shoots .33 and Vickers and Maxim .30 ammunition. In the beginning of the war the Colt gas-operated gun was also used on aeroplanes, as were also the Hotchkiss and Benet-Mercier. The first gun shooting 400 shots a minute was similar to the Vickers.

Owing to the ease with which the cotton-belts containing the cartridges on Vickers guns jam, it was used only for fixed positions in front, whereas the Lewis was employed in the observer’s nacelle and other positions which required sudden change in the aim. As many as half a dozen machine-guns were mounted on some of the large bombers in the last days of the war.

Many attempts to mount cannon on aircraft have been made, but owing to the recoil, the room necessary for mounting and manipulating, and the speed with which the gunner and the target move through the air, not much success was attained.

Captain Georges Guynemer, the first great French flier to down more than fifty Hun planes, is credited with mounting a one-pounder on his Nieuport, single-seater. It could not shoot through the propeller, so it was arranged to shoot through the hub. The gun was built into the crank-case, the barrel protruding two inches beyond the hub. It is said that Guynemer brought down his forty-ninth, fiftieth, fifty-first, and fifty-second victims with this type of gun; but because of the fifty pounds extra weight above that of the machine-gun it was an impediment.

Attempts to use on aeroplanes the Davis non-recoil gun, invented by Commander Davis of the United States navy, have not been entirely successful. The two-pounder is 10 feet long, weighs 75 pounds, and shoots 1.575 shell with a velocity of 1,200 feet a second. The 3-inch Davis fires a 12-pound shell and weighs 130 pounds.

Several other guns have been used, and with the increase in the size of planes there ought to be much increase in the size of aeroplane guns.

CHAPTER VII

DEVELOPMENT OF THE LIBERTY AND OTHER MOTORS

DEBATE IN REGARD TO ORIGIN OF LIBERTY MOTOR—LIBERTY-ENGINE CONFERENCE, DESIGN, AND TEST—MAKERS OF PARTS—HISPANO-SUIZA MOTOR—ROLLS-ROYCE—OTHER MOTORS