Here, then, commences another long story of delay and disappointment in these efforts to obtain a successful launch.
Continuing The First Airplanes,
with a selection from Annual Report of Smithsonian Institution by Samuel Langley published in 1897. For works benefiting from the latest research see the “More information” section at the bottom of these pages. This selection are presented in 2.5 installments for 5 minute daily reading each.
Previously in The First Airplanes.
[Dr. Langley then describes his first attempts at building an aerodrome which should contain some form of engine and so support and drive itself by its own power. Over these models, none of them large enough to support a man, he worked for years. He finally succeeded in constructing a gasoline engine which combined sufficient strength with sufficient lightness, and in so balancing an aerodrome that he believed it could fly. He then secured an experimental station on the bank of the Potomac River, near Washington, that his machine might fall into the water rather than on land, and so escape destruction.]
And now the construction of a launch apparatus, dismissed for some years, was resumed. Nearly every form seemed to have been experimented with unsuccessfully in the smaller aerodromes. Most of the difficulties were connected with the fact that it is necessary for an aerodrome, as it is for a soaring bird, to have a certain considerable initial velocity before it can advantageously use its own mechanism for flight, and the difficulties of imparting this initial velocity with safety are surprisingly great, and in the open air are beyond all anticipation.
Here, then, commences another long story of delay and disappointment in these efforts to obtain a successful launch. . . . I pass over a long period of subsequent baffled effort, with the statement that numerous devices for launching were tried in vain and that nearly a year passed before one was effected.
Six trips from the laboratory to the Potomac station] and trials were made in the first six months of 1894 without securing a launch. On the 24th of October a new launching piece was tried for the first time, which embodied all the requisites whose necessity was taught by previous experience, and, saving occasional accidents, the launching was from this time forward accomplished with comparatively little difficulty.
The aerodromes were now, for the first time, put fairly in the air, and a new class of difficulties arose, due to a cause which was at first obscure — for two successive launches of the same aerodrome, under conditions as near alike as possible, would be followed by entirely different results. For example, in the first case it might be found rushing, not falling, forward and downward into the water under the impulse of its own engines; in the second case, with every condition from observation apparently the same, it might be found soaring upward until its wings made an angle of sixty degrees with the horizon, and, unable to sustain itself at such a slope, sliding backward into the water.
After much embarrassment the trouble was discovered to be due to the fact that the wings, though originally set at precisely the same angle in the two cases, were irregularly deflected by the upward pressure of the air, so that they no longer had the form which they appeared to possess but a moment before they were upborne by it, and so that a very minute difference, too small to be certainly noted, exaggerated by this pressure, might cause the wind of advance to strike either below or above the wing, and so produce the salient difference alluded to. When this was noticed all aerodromes were inverted, and sand was dredged uniformly over the wings until its weight represented that of the machine. The flexure of the wings under those circumstances must be nearly that in free air, and it was found to distort them beyond all anticipation. Here commences another series of trials, in which the wings were strengthened in various ways, but in none of which, without incurring a prohibitive weight, was it possible to make them strong enough. Various methods of guying them were tried, and they were rebuilt on different designs — a slow and expensive process. Finally, it may be said in anticipation (and largely through the skill of Mr. Reed, the foreman of the work), the wings were rendered strong enough without excessive weight, but a year or more passed in these and other experiments.
In the latter part of 1894 two steel aerodromes had already been built which sustained from forty to fifty per cent of. their dead-lift weight, and each of which was apparently supplied with much more than sufficient power for horizontal flight (the engine and all the moving parts, furnishing over one horse-power at the brake, weighed in one of these but twenty- six ounces) ; but it may be remarked that the boilers and engines in lifting this per cent of the weight, did so only at the best performance in the shop, and that nothing like this could be counted upon for regular performance in the open. Every experiment with the launch, when the aerodrome descended into the water, not gently, but impelled by the misdirected power of its own engines, resulted at this stage in severe strains and local injury, so that repairing, which was almost rebuilding, constantly went on; a hard but necessary condition attendant on the necessity of trial in the free air. It was gradually found that it was indispensable to make the frame stronger than had hitherto been done, though the absolute limit of strength consistent with weight seemed to have been already reached, and the year 1895 was chiefly devoted to the labor on the wings and what seemed at first the hopeless task of improving the construction so that it might be stronger without additional weight, when every gram of weight had already been scrupulously economized. With this went on attempts to carry the effective power of the burners, boilers, and engines farther, and modification of the internal arrangement and general disposition of the parts such that the wings could be placed farther forward or backward at pleasure, to more readily meet the conditions necessary for bringing the center of gravity under the center of pressure.
We want to take this site to the next level but we need money to do that. Please contribute directly by signing up at https://www.patreon.com/history