The Conference on Aerial Navigation in Chicago in August, 1893 brought out a number of experimenters whose ventures had theretofore been unpublished.
One of these, Mr. E. C. Huffaker of Tennessee, had been experimenting with a model somewhat resembling the "effigy" of Mr. Lancaster. It consisted in a rectangular surface of fabric made concavo-convex by a rigid front spar with curved ribs at right angles thereto, so as to resemble the cross-section of a soaring bird s wing A cross stick attached thereto carried a balancing horizontal tail, the center of gravity being determined at the front by loading with lead. The area of sustaining surface was 2 sq. ft., and when held by the cross stick at arm's length overhead, vibrating between two fingers and
facing a wind of 35 miles per hour (6 lbs. pressure at right angles), the weight sustained (or lift) was estimated at 2 lbs. to the square foot, or that corresponding to an angle of 10° upon a flat plane, while in point of fact the model seemed to be horizontal, and the force required to hold it in the wind was very small.
When the model was let go in a steady breeze it would rise to a height of 12 or 15 ft., slowly retreating from the wind but always facing it; then, tipping slightly forward it would descend into the face of the wind, all these effects being easily explained in a horizontal current.
When projected forward by hand, the model would sail away in steady flight with a velocity of about 17 miles per hour, and then descend on a gradient of about 1 in 15. If thrust rapidly forward it would rise some 8 or 10 ft.. and then, hanging suspended for a moment, it sailed forward to the ground.
These experiments are interesting as confirming what has hitherto been said concerning the greater lift appertaining to concavo-convex surfaces, and it is to be hoped that they will be continued.
The other experimenter was Mr. J. J. Montgomery, of California. He had, some years previously, constructed a soaring apparatus, consisting of two wings, each 10 ft. long by an average width of 4 1/2 ft., united together by a framework to which a seat was suspended, and provided with a horizontal tail which could be elevated or depressed by pulleys. The wings were arched beneath, like those of a gull, and afforded a sustaining area of about 90 sq. ft. The weight of the apparatus was 40 lbs., and that of the experimenter some 130 lbs. more.
Mr. Montgomery took this apparatus to the top of a hill nearly a mile long, which gradually sloped at an angle of about 10°, and placing himself within the central framework, the rods of which he grasped with each hand, ready to sit down, he faced a sea breeze steadily blowing from 8 to 12 miles an hour, and gave a jump into the air without previous running.
He found himself at once launched upon the wind, and glided gently forward, almost horizontally at first, and then descended to the ground, finding that he could mean while direct his course by leaning to one side or the other. The total distance glided was about 100 ft., and the sensation was that of firm yet yielding and soft support, being quite similar to the experience of M. Mouillard, as already described, except that there was no apprehension of disaster.
Mr. Montgomery carried his machine back to the top of the hill and prepared to repeat the experiment but as soon as he got into position the apparatus began to sway and to twist about in the wind; one side dipped downward, caught on a small shrub, and, as quick as a flash, the operator was tossed some 8 or 10 ft. into the air, overturned, and thrown down headlong. He fortunately fell without serious injury, and found, as soon as he recovered himself, that one side of his machine was smashed past mending.
This experience led him to design and build a second soaring apparatus, in which he endeavored to relieve undue pressure upon either side by providing a diagonal hinge in each wing, along which the rear triangle might fold back (it was restrained by a spring) and yield to a wind gust. This apparatus measured some 132 sq. ft. of sustaining surface, and weighed 45 lbs. It was not successful; several trials were made, but no effective lift could be obtained with it. This was attributed to the fact that the wings had been made true planes (flat) instead of being arched underneath as in the first machine.
So a third apparatus was designed and built. The wings were each 12 ft. long by an average width of 6 ft., and were given the cross-section and front sinuosity of those of a soaring vulture. They were so built and braced as to allow rotation in a socket at the front of the frame which supported the seat. A hinged tail was added, as in the two previous trials, and the machine weighed 50 lbs.
This last apparatus proved an entire failure, as no lifting effect could be obtained from the wind sufficient to carry the 180 lbs. it was designed to bear. Mr. Montgomery then turned his attention to other matters, but he has since made a more careful and complete study of the principles involved, and he expects to resume his experiments.
The foregoing pages comprise all the experiments, the result of which has been published, which the writer has been able to collate, and which he has considered of sufficient importance to be described in this account of ÏProgress in Flying Machines." Other important experiments are pending or in partial progress; but the designers of these have as yet given out no information for publication, and indeed could scarcely do so concerning tentative plans, subject to constant modifications.
The writer has gathered from the newspapers, accounts of some other experiments, but these seem to be so erroneously or vaguely described that no instruction could be obtained by republishing them. It has been the aim of the writer throughout to gather all the information possible but only to publish that which was reliable and instructive.
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