CHAPTER VII
From time immemorial man has admired the aërial evolutions of wing-gifted creatures, and aspired to imitate them. But which evolutions should he attempt first? Which if any are practicable for the ponderous lord of creation? The question is still pertinent.
Nature in her bounty bewilders us with wondrous models. All about and overhead, with exquisite art, they challenge us to float or fly. Before the flower-bell drifts the ruby-throat, his long bill in the honey-hearted bloom; now bulletlike he leaps through boundless space. Why not adopt that style of locomotion? Call your rainbow equipage to the door, and take the family forth in purple state, to the music of melodious wheels.
If the humming bird will not serve, look above you. There rides the dark-winged master of aërial motion, throned like a god on the impetuous wind. Mark his majestic sweep as all day long, with unbeating pinion, he scours the wide plain and rugged regions of the hills, unwearied, reposeful, deliberate; now skimming the fragrant forest, or meadow; now scaling the precipice, or swinging above the abyss; now soaring cloudward beyond the range of human vision. There is a model for the ambitious and the brave!
Or turn to mid ocean when the hurricane, shearing the tops of the arched billows, scatters them in foam and spray over the watery chaos, and the big ship strains in the storm. See the long-winged albatross, white vision of joy in the darkness, careering all playfully round the imperiled vessel, and above the monstrous waves; wheeling in glad curves, frolicking in the face of the tempest, riding, without toil or trepidation, the rudest[19] winds a thousand miles over the sea. What a jocund pace for man!
Of all the charming modes of flight now possible to us it is certain that our ancestors could copy but one with any hope of success. Minus motive power they could not imitate the direct flight of the homing pigeon, much less the mid-air pause of the bumblebee floating round a daisy. Hence there remained to them only passive flight on nonvibrant wings. The gliding of vultures, of gulls, and of certain quadrupeds and fishes, they could imitate with profit; but when they essayed power flight they invariably and egregiously failed.
The art of aviation presents two main groups of fliers. The first comprises the various man kites, parachutes, gliding machines, soaring machines. These may be called passive flyers, because they carry no motive power, but ride passively on the air by the force of gravity or a towline.
The second group comprises the bird-like flap-wing machines, called orthopters by technical people; the screw-lift flyers, called helicopters; the aëroplanes, also called monoplanes, biplanes, triplanes, according to the number of superposed main lifting surfaces; and lastly the gyroplanes, whose sustaining surfaces may turn over and over, like a falling lath, or whirl round and round, like a boomerang. These all may be called dynamic, or power, flyers. The technical names, however, are not so important, as they are numerous; for the whole aëronautic nomenclature is in a formative, not to say chaotic, state. We may, therefore, like Adam, name the creatures as they pass before us for review or discussion.
Disregarding the crude essays at human flight, recorded in the early literature and history of many peoples, we may notice first the well authenticated sketches of Leonardo da Vinci. His fertile mind conceived three distinct devices for carrying a man in the air. But he and his successors for nearly four centuries could do little more than invent. For lack of motive power they could not navigate dynamic flyers, however ingeniously contrived.
Fig. 26.—Da Vinci’s Helicopter.
Da Vinci’s first design, as shown in Fig. 26, provides the operator with two wings to be actuated by the power of both arms and legs, through the agency of very ingenious harness. With this device an acrobat could fly forward and downward, to the delectation of a multitude; but he would have to be caught on something soft to escape injury. Since Leonardo’s day the experiment has been tried occasionally, with varied results, sometimes grotesque, sometimes tragic. He doubtless realized the impracticability of an orthopter actuated by human muscle, and yet he has had many followers. The orthopter is still a favorite device cultivated by a few persons who propose to work its wings by means of a gasoline motor. Doubtless the feat is physically possible, and may be accomplished in time.
Fig. 27.—Da Vinci’s
Parachute.
Da Vinci’s second flyer was a helicopter, as shown in Fig. 26. An aërial screw 96 feet in diameter was to be turned by a strong and nimble artist who might, by prodigious effort, lift himself for a short time. Though various small paper screws were made to ascend in the air, the larger enterprise was never seriously undertaken. Many subsequent inventors developed the same project; but the fellow turning the screw always found it dreadful toil and a hopelessly futile task. Of late the man-driven helicopter has been abandoned, but the motor-driven one is very much cultivated. Scores of inventors in recent years, aided by light motors, have been trying to screw boldly skyward, and some have succeeded in rising on a helicopter carrying one man.
Da Vinci’s third scheme for human flight, as shown in Fig. 27, was a framed sail on which a man could ride downward, if not upward. This device never fails to navigate with its confiding sailor. Sometimes he lands in one posture, again in another; but voyage he must, with the certainty of gravitation. Leonardo is, therefore, the father of the parachute. This, in turn, has had a varied offspring. The common parachute, the aërial glider, the soaring machine, or passive aëroplane, that rides the wind without motive power and without loss of energy.
The foregoing sketches by the great artist were made toward the year 1500, and there the science stood for nearly three centuries. Much speculation followed, but no substantial progress. Mathematicians proved by figures the inadequacy of the human muscle to achieve human flight. Dreamers demonstrated the same by launching themselves from high places, and breaking their bones on the unfeeling earth, before unpitying crowds. Finally came the balloon, giving a new impetus to an embryo art.
The earliest of Da Vinci’s aëronautic ideas to be practically realized was the parachute. The exact date of its first employment is not exactly known. In the year 1617 Fauste Veranzio published in Venice a good technical description of the construction and operation of the parachute, accompanied by a clear illustration, as shown in Fig. 28. But the first authentic account of a parachute descent of a human being is that given by Sebastien Lenormand. This dauntless inventor, on December 26, 1783, descended from the tower of the Montpelier Observatory, holding in either hand an umbrella sixty inches in diameter. A few days later he sent to the Academy of Lyons the following description of his improved parachute, illustrated in Fig. 29:
“I make a circle 14 feet in diameter with a heavy cord; I attach firmly all around, a cone of linen whose height is 6 feet; I double this cone with paper laid on the linen to render it impermeable to air; or better, instead of linen, taffeta covered with gum elastic. I place all about the cone small cords, which are attached below to a wicker frame, and forming with this frame an inverse truncated cone. Upon this frame I place myself. By this means I avoid the ribs and handle of the umbrella, which would add considerable weight. I am sure to risk so little that I offer to make the experiment myself, after once having tried the parachute with different weights to make sure of its solidity.”
Fig. 28.—Veranzio’s Parachute.
Previous to Lenormand’s experiments, Blanchard, the aëronaut, had dropped small parachutes from his balloon, sometimes carrying animals, but never a human being. For unaccountable reasons the world had to wait fourteen years longer to see a man make the new familiar parachute descent from a balloon. On October 22, 1797, in presence of a large crowd Jacques Garnerin ascended in a closed parachute to a height of 3,000 feet, then cut loose. The people were astonished and appalled; but they soon saw the umbrella-shaped canvas spread open and oscillate in the sky with its human freight. As it was but eight yards in diameter, it descended rapidly and struck the ground with violence, throwing Garnerin from his seat. He escaped with a bruised foot, mounted a horse, and returned to the starting point, where he received a lively ovation.
Fig. 29.—Lenormand’s Parachute, 1784.
After this experiment, parachute descents became popular the world over, and have been repeated up to the present time substantially without change. A slight improvement in the construction was made by cutting away the top of the canvas, thus allowing the air to escape sufficiently to check the oscillations; but no radical change in the design has come into general use. It would seem easy to have transformed the craft into a traveling parachute gliding down the sky like a great bird on out-stretched wings. Such a device would enable the aëronaut to sail some miles and direct his course in the air. If fair skill had been acquired it might have hastened the advent of human flight twenty years, so far as it is practicable without the aid of the internal combustion motor. For two decades ago Maxim produced an abundantly powerful steam engine; but could find no one to furnish him a manageable glider on which to mount it. Now, indeed, such gliders are available; but they were developed by aviators, not by balloonists, or parachutists, who should have effected that advance many years ago.
Curiously enough, Nature has furnished a traveling parachute which seems never to have been imitated by man, though not difficult to copy. It is a large two-winged seed, which when dropped in any poise, immediately rights itself, and glides gracefully through the air. The seeds grow on a tree in India, bearing the name Zanonia Macrocarpa, and when shaken from its branches look like so many sparrows sailing earthward in wide curves. Artificial gliders of this type are easy to construct, and would make interesting toys. However, if man has not copied such natural models, he has done much better, by making his gliders concave below instead of concave upward, as are the beautiful Indian seeds.
An interesting model of a traveling parachute, quite as efficient as the gauzy-winged seed, is shown in the accompanying figure. It is a sheet of paper twenty inches long by four inches wide, having a quarter inch strip of tin folded in its forward margin, and having its rear margin turned upward slightly, to steer the little craft from a too steep descent. In order to improve the stability of the paper plane, its sides may be bent upward. The model when dropped in any attitude quickly rights itself, and sails down a gently sloping course, the rear margin functioning as a rudder or tail.
Fig. 30.—Paper Traveling Parachute.
One of the earliest trustworthy and scientific accounts of experimentation with an aërial glider was given by Sir George Cayley in Nicholson’s Journal, in 1809 and 1810. After a careful study of the principles of stability, he, in 1808, constructed a glider spreading 300 square feet of surface and weighing with its load 140 pounds. It had wing surfaces slightly inclined to each other, and a tail inclined enough to determine a gentle downward course. “When any persons,” says Cayley, “ran forward in it with his full speed, taking advantage of a gentle breeze in front, it would bear him up so strongly as scarcely to allow him to touch the ground, and would frequently lift him up and carry him several yards together. It was beautiful to see this noble white bird sail majestically from a hill to any given point of the plain below it, with perfect steadiness and safety, according to the set of the rudder, merely by its own weight, descending in an angle of about 18° with the horizon.”
Sir George Cayley made a brave start in the science of dynamic flight, marshaling to it all the mechanical resources of his day. He applied the most reliable data of fluid resistance then available. He formulated the laws of equilibrium and control of a flying machine quite as well as any of his successors for two generations. He estimated the propulsive power required to carry a man, and computed the weight of the newly invented Bolton and Watt steam engine capable of supplying that power. He even conceived the idea of burning a gas or inflammable vapor behind a piston, thus anticipating the modern aëronautical motor. But the project as a whole was too formidable at that time for the genius of this one man, or of his generation of colleagues. Sailing flight they could have practiced with profit to the advancement of aviation, but power flight on a practicable scale had to await the long evolution of the internal combustion engine.
The next great advancement in the devices and principles of aviation was made by another Englishman, and a worthy successor to Sir George Cayley. In 1842 Mr. Henson patented the aërial equipage shown in the accompanying illustration. It was what in present-day parlance is called a monoplane, being in fact the first commercially planned aëroplane known to history. As seen at a glance it consisted of a large sustaining surface rigidly trussed and driven through the air by two propellers actuated by a steam engine. It was to be guided up and down by means of a horizontal rudder, and guided to the right and left by means of a vertical rudder, seconded by a keel cloth; both rudders being at the rear of the large plane. The machine was designed to be launched by running down an inclined plane or track. Fuller details of this first patent aëroplane are given in the following official description in the South Kensington Museum of a model aëroplane constructed by Henson and Stringfellow:
“The model consists of an extended surface, or aëroplane, of oiled silk or canvas, stretched upon a bamboo frame made rigid by trussing both above and below. A car is attached to the underside of the aëroplane to contain the steam engine, passengers, etc. It has three wheels to run freely upon when it reaches earth. Two propellers, three feet in diameter, are shown with their blades set at 45°. They are operated by endless cords from the engine. Behind these is a fan-shaped tail stretched upon a triangular frame capable of being opened out, closed, or moved up and down by means of cords and pulleys. By this latter arrangement ascent or descent was to be accomplished. A rudder for steering sideways is placed under the tail, and above the main aëroplane a sail was to be stretched between two masts rising from the car, to assist in maintaining the course. When in motion the front edge of the machine was to be raised in order to obtain the required air support. To start the model it was proposed to allow it to run down an incline—e.g., the side of a hill, the propellers being first set in motion. The velocity gained in the descent was expected to sustain it in its further progress, the engine overcoming the head resistance when in full flight. Experiments were eventually made on the Downs near Chard, in Somerset, and the night trials were abandoned, as the silk became saturated from a deposit of dew. After many day trials, down wide inclined rails, the model was found to be deficient in stable equilibrium for open-air experiments, little puffs of wind or ground currents being sufficient to destroy the balance. The actual machine was never constructed, but in 1847–48 F. Stringfellow built a model which is supposed to be the first flying machine to perform a successful flight.”
PLATE XII.
HENSON’S AËROPLANE.
ADER’S AËROPLANE.
Photo E. Levick, N. Y.
The creation of Henson’s flying machine at that early period is one of the most original and fruitful achievements in the century-long development of the modern aëroplane. Barring the torsional wing-tips invented more recently, it hardly differs in principle from the successful monoplane of to-day. The same mode of propulsion, the same mode of sustention, the same mode of launching and lighting, the same mode of steering and control. What has been added since is not so much original invention as perfection of detail through the combined efforts of many designers. After Cayley, Henson, as nearly as any one person was the inventor of the flying machine. He did not bring his conception to practical maturity, nor was that to be expected; but he did lay down the broad lines which have led others to success. His ideas still feature every practical aëroplane, and particularly every successful monoplane. Indeed, it is now possible to construct an aëroplane from Henson’s description that will fly, even in breezy weather, with a stability practically as good as that of the early Voisin and Antoinette machines before the use of the aileron or torsional wing was practiced. It is all a question of wise proportioning and sufficient motive power.
So much for Henson’s contrivance as an abstract invention. The concrete, full scale machine was to spread 6,000 square feet of surface, weigh 3,000 pounds, and be propelled by a high pressure steam engine of 25 or 30 horse power. The machine was not completed on a large scale, and wisely so; for it was inadequately powered, and, moreover, required many refinements of detail to make it entirely practical. These improvements had to be left to succeeding inventors with accumulated experience and resources.
In 1844 Mr. Henson began the construction of a steam-driven model, in partnership with his friend, Mr. Stringfellow, who designed the motor for it. They experimented together for some weeks with only meager success, but gaining valuable experience. A model of the Henson-Stringfellow machine is on exhibition at the South Kensington Museum.
In 1846 Stringfellow built a steam model aëroplane about the size of a large soaring bird, and weighing all together, with fuel and water, 6½ pounds. A special feature of this model was that its main surfaces were sloped like the wings of a bird, slightly concave below and feathered toward the back; thus making it more efficient and stable in flight. With a good head of steam, and propellers whirling, the model ran down a stretched wire, leaped into the air “and darted off in as fair a flight as it was possible to make, to a distance of about 40 yards.” Thus the first power-driven aëroplane to fly successfully was the little steam model constructed by Stringfellow in 1846.
Fig. 31.—Wenham’s Aëroplane, 1866.
In 1866, two decades after the flight of Stringfellow’s monoplane, Mr. F. H. Wenham, another Englishman illustrious in the annals of aëronautics, patented the multiplane; that is, an aëroplane comprising two or more superposed surfaces. This proved to be a valuable contribution to the art of aviation, and continues in use at the present time. The device furnished an increase of sustaining surface without enlargement of the ground plan. It moreover lends itself conveniently to a strong and simple trussing of the surfaces. Some designers protest that superposed surfaces blanket one another; but the advantages just named seem amply to compensate for this objectionable feature. If the surfaces be properly spaced, very little interference is found; moreover, any blanketing that may occur diminishes the drift as well as the lift,[20] though not necessarily in the same proportion.
Wenham’s aëroplane is illustrated in Fig. 31. The rider lies underneath the multiple wings, so as to diminish the resistance to progression through the air. The apparatus could thus be used as an aërial toboggan for coasting down the atmosphere. To prolong the flights two flappers actuated by a treadle were to be employed, their ends being hinged at a point above the operator’s back. Though the device was patented, no very serious efforts were made to operate it practically. Once, indeed, the inventor took his glider to a meadow and mounted it, during a lull in the evening wind, but soon a gust caught him up, carried him some distance from the ground and toppled him over sidewise, breaking some of the surfaces. The machine disclosed some good working principles; but it was inadequately ruddered, and too feebly constructed, to weather the buffets of the prevailing ground currents.
PLATE XIII.
STRINGFELLOW’S AËROPLANE (FRONT).
(Courtesy Smithsonian Institution.)
STRINGFELLOW’S AËROPLANE (SIDE).
(Courtesy Smithsonian Institution.)
Adopting the scheme of superposed surfaces then recently devised by Wenham, Mr. Stringfellow in 1868 constructed the interesting steam-driven model shown in Plate XIII. This consists essentially of three superposed planes, rigidly connected by rods and diagonal wires, propelled by a pair of screws actuated by a high pressure steam engine, and guided by a tail. The three planes aggregated 21 feet in length and 28 square feet in surface; totaling, with the tail, 36 square feet. The engine was rated at one third of one horse power. Its weight is not known, but may be roughly surmised from the fact that a separate engine exhibited simultaneously by Stringfellow weighed thirteen pounds per horse power. The model was entered for competition in the London Aëronautical Exhibition of 1868. In actual operation, however, it seems not to have excelled the monoplane of 1846; but still it is of much interest as being the prototype of the multiple-wing aëroplane now in common use. It seems to have been the first aëroplane having two or more sustaining surfaces joined by rods and stayed by diagonal cords after the manner of a Pratt truss. This historic little model was purchased by Professor Langley for the Smithsonian Institution, and is now to be seen suspended from the ceiling of the National Museum, beside Langley’s own models and Lilienthal’s epoch-making glider.
Fig. 32.—Penaud’s Aëroplane Toy, 1871.
In 1871 M. A. Penaud produced the interesting toy aëroplane shown in Fig. 32. The model is propelled horizontally forward by a single screw, actuated by twisted rubber, and is fastened, as shown, to the middle of a long stick or backbone. The center of mass of the machine is well to the front, tending to plunge the model earthward like a heavy-headed arrow; but this down-diving is promptly checked by the tiny rudder which is so inclined as to counteract the diving proclivity. That is to say the rudder dips so as to receive the aërial impact on its upper surface; which impact increases with the speed of flight and causes the bow to rise, until the weight before the wings just balances the impact on the rudder at the rear. The equilibrium is thus automatic, on the principle expounded by Sir George Cayley sixty years earlier. This quaint little bird when liberated in the Garden of the Tuileries flew a distance of 131 feet in eleven seconds, much to the delight of some members of the French Society for Aërial Navigation. It may be added that Penaud, who was a most promising and clever aëronautical inventor, contemplated a twin-screw monoplane large enough to carry two men, but died in his early manhood, before the project could be realized.
Fig. 33.—Tatin’s Aëroplane Model, 1879.
In 1879 M. Victor Tatin made some very promising tests with the model shown in Fig. 33, so promising, in fact, as to convince many that human flight was even then practicable. This little flyer was a twin-screw monoplane mounted on wheels, and actuated by an oscillating compressed air engine, the whole machine weighing 3.85 pounds, and supported by a silk plane measuring 16 by 75 inches. The central body of the aëroplane was a thin steel tube three feet long by four inches in diameter containing the compressed air, and weighing only one pound and a half, though strong enough to endure a pressure of twenty atmospheres. When the model was allowed to run round a board walk 46 feet in diameter, tethered to a stake at the center, it quickly acquired a speed of 18 miles an hour, rose in the air, and flew a distance of fifty feet.
A remarkable deduction from the very careful measurements made with this machine was that it carried at the rate of 110 pounds per tow line horse power, when flying at an angle of 8 to 10 degrees. Mr. Tatin concluded: “These experiments seem to demonstrate that there is no impracticability in the construction of a large apparatus for aviation, and that perhaps even now such machines could be practically used in aërial navigation. Such practical experiments being necessarily very costly, I must to my great regret, forego their undertaking, and I shall be satisfied if my own labors shall induce others to take up such an enterprise.”
Tatin’s faith in the practicability of a large aëroplane was later voiced by Mr. Chanute in his valuable book, Progress in Flying Machines, published in 1894, but now unfortunately out of print. Recalling that Maxim had recently produced a large motor weighing complete only ten pounds per horse power, he says: “Aviation seems to be practicably possible, if only the stability can be secured, and an adequate method of alighting be devised.” Since the above quoted facts and opinions were published, no competent man well informed in the science of aviation has for one moment doubted the feasibility of human flight.
Fig. 34.—Hargrave’s Model Screw Monoplane, 1891.
In 1891, twelve years after Tatin’s experiment, Lawrence Hargrave, of Sydney, Australia, made a similar compressed air monoplane, with a single-screw propeller, but without wheels for launching and lighting. The model, which is shown in Fig. 34, had a wing-spread of 20 square feet, weighed about three pounds, and flew 128 feet in eight seconds. The weight carried was at the rate of 90 pounds per horse power, a very encouraging result. Two years later he described a small steam engine which he had developed, weighing 10.7 pounds per horse power, and capable of driving the model about two miles, though he did not use it for that purpose, being engrossed with other researches.
One interesting outcome of his numerous experiments was the Hargrave Kite, now more familiarly known as the box kite. A good example of his kites is the type shown in Fig. 35. This consists of two arched biplanes mounted tandem on a backbone, or connecting framework. The kite floats steadily, and was thought suitable for the body of a flying machine to be driven by an engine and propeller. Thus meteorology is indebted to aëronautics for its most useful kite.
Fig. 35.—Hargrave’s Kite.
A very novel and interesting type of aëroplane model was tested by Mr. Horatio Phillips in 1893. After careful preliminary experiments with various forms of curved “sustainers,” or lifting surfaces, tested in a wind tunnel, to determine which were most suitable wing forms, he finally constructed the flying apparatus shown in [Plate XIV]. This consisted of a compound aëroplane composed of many superposed narrow curved slats, the whole resembling an open Venetian blind. These curved blades, or sustainers, measured 12 feet long, 1.5 inches wide, 2 inches apart, and were held in a frame sharpened to cleave the air with slight resistance. The entire aëroplane spread 136 square feet of lifting surface, and was mounted on a truck as shown, carrying a steam engine and boiler, to actuate a two blade propeller 6 feet in diameter. The whole apparatus weighed 330 pounds, to which a dead load was usually added, and ran around a circular wooden track 628 feet in circumference, being tethered at the center, as in Tatin’s experiment. The apparatus readily lifted itself, when running at a speed of 28 miles an hour, and carried at the rate of 72 pounds per horse power, the added load weighing at times nearly one fourth that of the machine itself. The ultimate purpose of the experiment was to prepare the way for a one-man aëroplane like that shown in the lower part of the figure. This latter model actually carried a man across a field in 1904, but was found defective in longitudinal balance, because perhaps of its inadequate horizontal rudder. Apparently Mr. Phillips had in 1904 a machine capable of well-balanced flight, if he had made the rudders large enough, and provided a mechanism for rotating the slats at either wing end, so as to control the lateral poise, as proposed by the present writer in 1893, for practically that same flier (see [page 229]).
Phillips’s aëroplane shows a distinct advance over its predecessors, even Wenham’s multiplane, because of the careful curving of the sustainers. Tatin’s flat wing machine had, indeed, shown a greater efficiency as a whole, but that was likely due to less proportionate body resistance. To Phillips we owe the introduction of superposed arched surfaces, now so commonly used in mechanical flight. Whether he was wise in using so many narrow wings, instead of a few broad ones, was a question to be answered by precise measurement.
Prof. S. P. Langley, like Mr. Hargrave, made numerous flying models, trying, in turn, the power of twisted rubber, compressed air and steam. He constructed scores of gauzy winged contrivances which flitted about like huge butterflies or birds, till their mission was accomplished—that of illustrating a scientific principle to his inquiring mind. One by one they came into existence, enjoyed an ephemeral life, and then were consigned to the aëronautical attic of the Smithsonian Institution, a storehouse of quaint flying creatures. It was a most interesting collection which well merited preservation as the “juvenile” creations of an illustrious man. But the first experiments of Langley, like the similar ones of Hargrave, were of value chiefly as training to the inventor himself; they were not important advances in the art of aviation. Such advances were to follow the long preliminary training.
PLATE XIV.
PHILLIPS’ TETHERED AËROPLANE.
PHILLIPS’ AËROPLANE.
On May 6, 1896, Dr. Langley launched the picturesque steam model, which, to his mind, first proved conclusively the practicability of mechanical flight. It was the crowning success, and, as he thought then, probably the termination of his aëronautic labors. “I have brought to a close,” says he, “the portion of the work which seemed to be peculiarly mine—the demonstration of the practicability of mechanical flight—and for the next stage, which is the commercial and practical development of the idea, it is probable that the world may look to others. The world, indeed, will be supine if it does not realize that a new possibility has come to it, and that the great universal highway overhead is now soon to be opened.”
As shown in [Plate XV], Langley’s first successful steam flying machine is a tandem monoplane[21] with twin screws amidships. It measures nearly 13 feet from tip to tip of its wings, about 16 feet along its entire length, and weighs with motor and propellers 30 pounds. The boiler weighs 5 pounds, the engine 26 ounces, and the power developed was between 1 and 1.5 horse power. The model is therefore somewhat larger than a large condor, and very much more powerful.
Being too small to carry a pilot, it was launched over water, to obviate wreckage on landing. The machine was capable of flying several miles continuously, but in the actual test on the Potomac River the flight was limited, in order to prevent the model passing beyond the shore. The flyer was placed on launching ways on the top of a houseboat, hurled rapidly forward by force of a spring, and liberated in space, with engine and propellers running at full speed. Its subsequent behavior has been graphically described by an eyewitness, Dr. Alexander Graham Bell, in the following passage, published in Nature, May 28, 1896:
“On the occasion referred to, the aërodrome, at a given signal, started from a platform about 20 feet above the water, and rose at first directly in the face of the wind, moving at all times with remarkable steadiness, and subsequently swung around in large curves of perhaps a hundred yards in diameter, and continuously ascending till its steam was exhausted, when at a lapse of about a minute and a half, and at a height which I judged to be between 80 and 100 feet in the air, the whole ceased turning, and the machine, deprived of the aid of its propellers, to my surprise did not fall, but settled down so softly and gently that it touched the water without the least shock, and was in fact immediately ready for another trial.
“In the second trial, which followed directly, it repeated in nearly every respect the actions of the first, except that the direction of its course was different. It ascended again in the face of the wind, afterward moving steadily and continually in large curves, accompanied with a rising motion and a lateral advance. Its motion was, in fact, so steady that I think a glass of water on its surface would have remained unspilled. When the steam gave out again it repeated for a second time the experience of the first trial when the steam had ceased, and settled gently and easily down. What height it reached at this trial I can not say, as I was not so favorably placed as in the first, but I had occasion to notice that this time its course took it over a wooded promontory, and I was relieved of some apprehension in seeing that it was already so high as to pass the tree tops by 20 or 30 feet. It reached the water in one minute and thirty-one seconds from the time it started, at a measured distance of over 900 feet from the point at which it rose.
PLATE XV.
LANGLEY’S STEAM MODEL.
(Courtesy Smithsonian Institution.)
LANGLEY’S GASOLENE MODEL.
(Courtesy Smithsonian Institution.)
LANGLEY’S TWO SURFACE GASOLENE MODEL.
(Courtesy Smithsonian Institution.)
“This, however, was by no means the length of its flight. I estimated from the diameter of the curve described, from the number of turns of the propellers, as given by the automatic counter, after due allowance for slip, and from other measures, that the actual length of flight on each occasion was slightly over 3,000 feet. It is at least safe to say that each exceeded half an English mile.
“From the time and distance, it will be noticed that the velocity was between 20 and 25 miles an hour, in a course which was constantly taking it ‘up hill.’ I may add that on a previous occasion, I have seen a far higher velocity attained by the same aërodrome when its course was horizontal.
“I have no desire to enter into detail further than I have done, but I can not but add that it seems to me that no one who was present on this interesting occasion, could have failed to recognize that the practicability of mechanical flight had been demonstrated.”
In passing it may be added that in 1899 this model was again flown successfully, having superposed surfaces; for its inventor all along recognized the structural advantage of the bridge trussing in biplanes. If he preferred the monoplane, or single-tier arrangement, it was because the best flights were obtained with such models.
Many persons now thought that Langley would do well to rest on his laurels, leaving to others the “commercial and practical development” of his ideas. But he had caught the aëronautic fever. Like many another poor son of fancy, he was haunted by magnificent dreams. Now, perhaps, was stirring in his mind that vision of his childhood when he lay on his back in the New England pasture and “watched a hawk soaring far up in the blue, and sailing for a long time without any motion of its wings, as though it needed no work to sustain it, but was kept up there by some miracle.” Mr. Andrew D. White declares that Professor Langley was a poet by nature. Whatever the dominant impulse, he followed his “aërodrome” like one possessed. It was the all engrossing pursuit of the latter years of his life, entailing how much vexation, toil and unjust censure!
In 1898 the Board of Ordinance and Fortification, after carefully studying the flights of 1896, appropriated $50,000 to enable Professor Langley to build a one-man flyer. He first tested a gasoline driven aëroplane having one fourth the linear dimensions of the man-carrying one. In external appearance this model resembled the steam “aërodrome,” described above, but was considerably larger. It spread 66 square feet of surface, weighed 58 pounds, and developed 2½ to 3 horse power. When ready for the test, August 8, 1903, this beautiful white-winged creature was taken to the middle of the Potomac, 40 miles below Washington, mounted on the launching ways, swiveled into the eye of the wind and shot forth like a stone from a catapult, her engine and propellers humming merrily.
The flight must have been very graceful and dignified, for it elicited commendation even from the squad of reporters present, men who customarily recorded such events with uncontrollable mirth and ridicule. Dr. Langley merely remarks: “This was the first time in history, so far as I know, that a successful flight of a mechanically sustained flying machine was seen in public.” It was also the first successful gasoline[22] aëroplane, and the forerunner of the host of flyers presently to spring up in all parts of the world. Its flight though very brief, owing to a surcharge of gasoline, was so satisfactory in all its dynamic features, that it seemed to justify an immediate launching of the one-man machine, with which like maneuvers were anticipated. As will appear in the sequel this prospect of fair sailing was beset with unsuspected shoals.
We have now traced the growth of the aëroplane from its earliest conception to the present time, as exemplified by working models. First came the parachute of da Vinci and others, whose sole function was to carry a weight softly to earth, with no provision for steadiness of motion, or control of direction. Then, in the beginning of the nineteenth century, arrived the gliders adjusted for steadiness, equilibrium and a predetermined slanting course in the air; beautiful passive birds, actuated by gravity, but riderless and awaiting the advent of artificial motive power. Then suddenly appeared Mr. Henson’s wonderful project; a large man-carrying aëroplane, provided with a motor, propellers, rudders, wheels for launching and landing—an impossible scheme for that day, but destined to be realized in the course of two generations. Henson’s idea was doubtless the most prolific in the history of aviation. After this followed the numerous instructive models, actuated by twisted rubber, steam, gasoline, compressed air—economic contrivances for ascertaining the secrets of propulsion, equilibrium and control, of the prospective man-flyer. These may be said to have demonstrated the practicability of man-flight, though many contemporaneous and allied experiments, to be noticed presently, all contributed to the triumphs subsequently achieved by the race of sanguine, daring and tireless inventors.
Fig. 36.—Launoy
and Bienvenu’s
Helicopter, 1784.
In this brief outline, the two other main types of flyers, the orthopters and helicopters, have been omitted. The orthopters, or wing flapping machines, have been very numerous, but have not yet approached practical success in use. Though a man-carrying orthopter has not yet been produced, an elegant pigeon-like model operated by rubber has been made by Pichancourt, which flies and balances nicely. The helicopters, or direct-lifting screws, have more than once raised their weight and that of the helicoptrist, or navigator. These latter, therefore, seem to be of sufficient interest to merit a short historical review.
Leonardo da Vinci, the fertile pioneer in aviation, missed one novel device worthy even of his genius. He constructed aërial screws of paper, but he did not endow them with motive force. Such an achievement was in his power, and would have ranked him with Archytas of Tarentum, who 400 b. c. invented the kite, and an artificial dove said to have flown, no one knows how. Having escaped da Vinci’s ingenuity, the power helicopter failed to materialize for three centuries, but finally appeared in France.
In 1784 Launoy and Bienvenu, the first a naturalist, the second a mechanician, exhibited before the French Academy the interesting toy shown in Fig. 36. This was the first power-driven helicopter, and is said to have lifted itself in the air quite readily. As may be observed it consists of two coaxial screws rotating in opposite directions actuated by the power of an elastic stick, like a bow. The screws were each about one foot in diameter and made of four feathers; one screw being fastened to the top of the rotating shaft, the other fastened to the bow, which rotated in the contrary direction. The little model excited much interest, particularly as its inventors expected to build a man-carrying helicopter on the same plan. The larger project was obviously without merit; for no combination of springs can maintain flight for more than a few seconds even on the most favorable scale.
A more powerful toy helicopter was produced by Mr. Horatio Phillips in England in 1842. This was a single aërial screw emitting jets of steam which compelled it to spin, on the principle of a lawn sprinkler, or a Hero engine. The whole apparatus weighed two pounds, and had screw blades inclined 20° to the horizon. The steam was generated by the combustion of charcoal, niter and gypsum, as in the fire extinguisher previously invented by the same ingenious man. The performance of this curious helicopter, is thus described by Mr. Phillips: “All being arranged, the steam was up in a few seconds, then the whole apparatus spun around like a top, and mounted into the air faster than any bird; to what height it ascended I have no means of ascertaining. The distance traveled was across two fields, where, after a long search, I found the machine minus the wings, which had been torn off from contact with the ground.”
“The distance traveled was across two fields.” For vagueness this surpasses the poet’s measure—“as far as oxen draw the plow in a day.” It would be most interesting to have an exact description of this classical experiment, when for the first time a flying machine rose in the air propelled by a heat motor. It would be desirable also to know the possibilities of such a helicopter, particularly since Prof. Cleveland Abbe has proposed to employ a like agent to carry meteorological instruments into the higher atmosphere.[23]
Fig. 37.—Forlanini’s Helicopter, 1878.
A still more ambitious helicopter was that shown in Fig. 37 invented by Professor Forlanini, an Italian Civil Engineer, and launched in 1878. The lower screw was fastened to the frame of a steam engine, the upper screw was attached to the crank shaft. Steam was supplied from the globe shown beneath, which was two thirds filled with water, and well heated over a separate fire just before an ascension. As the globe was merely a reservoir of hot water and steam, carrying neither fuel nor furnace, its power waned rapidly. The best flight lasted about twenty seconds, attaining a height of 42 feet. The apparatus weighed 77 pounds, spread 21.5 square feet of screw surface, and lifted about 26.4 pounds per horse power.
Many other helicopter models have been tried from time to time, with various sources of power, without, however, yielding any important results beyond those already given. But these were sufficiently encouraging. If a large machine could be made to lift as many pounds per horse power, it would be easy to build one competent to carry a man. That, indeed, has been done on several occasions. Of the various inventors who have built man-lifting helicopters M. Cornu and M. Bréguet, in France, seem to have been first to attain a measure of success. While their machines have raised a passenger directly from the ground, they have not yet maneuvered in horizontal flight with sufficient speed to be of practical service. However, a few helicoptrists in various countries are still industriously at work, and hope eventually to rival the aëroplanists in the mastery of flight. There will doubtless be room in the sky for both. Perhaps also there will be occupation and a mission for both.