PL. 93. QUARTER-SIZE MODEL AERODROME AT END OF FLIGHT, AUGUST 8, 1903 [◊]
In describing this flight immediately after it was made, Professor John M. Manly, who took the photograph shown in Plate [87], said: “The flight of the small aerodrome was an event which all who saw it will remember for the rest of their lives. We were, of course, in a state of considerable nervous excitement and tension, for, after weeks of delay from high winds, rains, and [p261] other uncontrollable causes, at last we had a day ideally suited to the test. This was, to be sure, not the great test, the final test, the test of the man-carrying flyer, but it was felt by all to be of almost equal importance, for if the balancing of the small aerodrome was correct, the large one would maintain its equilibrium, and the problem of human flight would be solved practically as well as theoretically. That the weather was now favorable for the test filled us with excitement. Again and again the favorable moment had seemed to come, and had gone again before we could make ready for it. The aerodrome was rapidly carried to the upper works of the house-boat and the observers and helpers went hastily to their positions. The large tug-boat was stationed directly ahead, almost in the line of flight, and about a mile from the house-boat. Signals of readiness were exchanged, and with every sense astrain we awaited the supreme moment. The rocket gave the starting signal, and instantly there rushed towards us, moving smoothly, without a quiver of its wings, with no visible means of motion and no apparent effort, but with tremendous speed, the strange new inhabitant of the air. Onward it moved, looking like a huge white moth, but seeming no creature of this world, not only on account of its size, its ease of movement and its wonderful speed, but also because of its strange, uncanny beauty. It seemed visibly and gloriously alive as it advanced, growing rapidly larger and more impressive. Straight at us it came, and for a moment there was a wild fear that it would come right on and crush itself against the ponderous tug-boat. There was a half impulse to move the tug-boat out of its way, but the aerodrome seemed to realize its danger and rapidly, though not abruptly or violently, as if it had intelligence and power of self-direction, it checked its speed and circled to the right, descending slightly. Soon it quickened its speed again and went straight ahead for about ten seconds, when it again checked its flight and descended, circling once more. Once again it attempted to increase its speed and rise, but it was too near the water, and in a few moments the waves had wet its propellers and wings, and it sank, a poor, bedraggled creature. But the vision of its beauty and power and seeming intelligence and life will long remain with those who saw its flight.”
After removing the model-launching track so that the final arrangements could be completed for testing the large machine, many weeks of delay were experienced, almost entirely due to the unusually bad weather conditions which prevailed, and which were unprecedented for the time of the year. However, on September 3 the weather became more suitable, and the aerodrome being in readiness the metal frame of the large machine was hoisted to the top of the boat and placed on the launching car, and the wings, rudder, etc., were then hoisted up and properly assembled and everything made ready for a flight. The parties with the telephoto cameras were sent to their stations on the shore, where definite base lines had been marked out so that with the data as to [p262] altitude and azimuth, which these cameras automatically recorded, the speed, height, etc., of the machine in flight could be accurately computed. After stationing the tug-boats at proper points, so as to render assistance should the aerodrome come down into the water at a considerable distance from the house-boat, it was found, upon attempting to start the engine, that for some reason it would not operate. The sparking battery which had been placed at the extreme rear of the aerodrome was found to be giving such a weak spark that it would not ignite the mixture in the cylinders. Upon removing the connection which grounded the terminal of the battery to the framework and replacing it by a large copper wire leading up to the engine so as to decrease the resistance of the circuit it was found that the battery still would not give sufficient spark. A large quantity of dry cells, such as were used for the engine, had been procured to insure against delay from lack of batteries, but upon attempting to get a new set from this reserve supply it was found that they, as well as the set that was on the machine, had so deteriorated that instead of giving eighteen amperes on short circuit they would give only three, which was not a sufficient current to enable the engine to operate. No shop tests on the large engine had been made since the large aerodrome had been brought down the river, as no provision had been made for properly supporting the aerodrome in the house-boat in such a way as to permit the large propellers to whirl around without causing damage, and, therefore, the batteries which had hitherto proved to be suitable had not had any special test since they had been brought down the river. As no batteries suitable for use were on hand, and as none could be procured from a point nearer than Washington, the test had to be abandoned for the day and the aerodrome removed to the interior of the boat.
It was at first impossible to account for the rapid deterioration of so large a number of dry cells, but it was later found that the damp, penetrating fogs which had been experienced for nearly two months were responsible for it, and that in order to preserve the batteries in such a climate it was necessary to place them in metallic boxes which could be nearly, if not quite, hermetically sealed. New batteries were immediately procured from Washington, and before again mounting the aerodrome on the launching track provision was made for testing the engine inside the house-boat.
PL. 94. HOISTING WING OF FULL-SIZE AERODROME [◊]
Up to this time the wings had been stored inside the house-boat by suspending them from the ceiling, but the time required to hoist them to the upper works on top of the boat, after the main body of the aerodrome had been placed on the launching car preparatory to making a flight, had added so greatly to the delay, and consequently to the difficulty of getting the machine entirely ready for a flight while the weather conditions remained suitable for a test, that it was decided to build some framework on the upper works and cover it with canvas so as to provide some boxes in which the wings could be [p263] stored whenever it seemed probable that a flight would soon be possible. Some of the difficulties experienced in hoisting these wings from the interior of the boat to the upper works may be appreciated by an inspection of Plate [94], where one of them is seen just ready to be hoisted from the raft. Only one wing at a time could be handled on the raft, even when there was no appreciable wind or roughness of the water, so that in order to hoist all four wings the raft had to be hauled around from the door at the end of the boat to the side where the wing was hoisted, and back again four times every time the machine was assembled preparatory to a flight. The necessity for making occasional tests of the engine in order to make sure that no trouble would be again experienced in having proper batteries, etc., for the engine when the machine was again on the point of being launched also made it imperative to remove the wings from the interior of the house-boat, as the tremendous blasts of air from the propellers would certainly have wrecked the wings had they remained in the boat while the engine was being tested.
After the wings had been stored in the “wing boxes,” thorough tests of the engine were made, and before there came another day which was at all suitable for a trial, it was accidentally discovered that the glued joints in the cross-ribs of the large wings had been softened by the moisture of the fogs which had penetrated everything, and that the joints had all opened up and left the ribs in a practically useless condition.
It will be recalled from the description of these cross-ribs, Chapter VI [◊], that the rib is composed of two channel-shaped strips, the edges of which are glued together while the strips are bent over a form which causes the ribs to maintain the curved form desired after the glue has hardened. Recalling these facts, it will be readily understood that there is at all times a considerable strain on the glued joints due to the two strips of wood trying to straighten out, and, therefore, if the glue should at any time become softened sufficiently to allow one strip to slide along on the other, the joint would open up and the rib would consequently become straight. When the construction of the hollow ribs was first contemplated it was realized that although the hollow construction would enable the ribs to be strong, and at the same time exceedingly light, yet it would make it imperative that the ribs be covered with a water-proof varnish in order to prevent the glue from being softened when the aerodrome came down into the water, as it was expected from the first that it would do at the end of its flight. Considerable time and attention had, therefore, been given to this very problem of securing a suitable water-proof varnish, and ribs coated with the varnish which was finally used had been submerged in water for more than 24 hours in testing this very point, and no softening of the glue could be detected after this long submergence. It had, therefore, been felt that the ribs had been given a test which was much more severe than any conditions which [p264] were likely to be met with, since the aerodrome would, in no case which could be anticipated, be in the water for so long a period as 24 hours, and no trouble from this source need be anticipated.