The Aerial Experiment Association, which was formed last summer by Dr. Alexander Graham Bell, has been actively engaged during the past three months in constructing an aeroplane. The machine, which is along the general lines of those now being built for the government by Mr. A. M. Herring and the Wright brothers, is shown in the accompanying illustrations. It consists of two superposed surfaces having a spread of 43 feet from tip to tip and a width of 6 1/2 feet from front to back at the center, which width gradually diminishes to 4 feet at the ends proper of the planes. The front edge of the upper plane extends out 4 feet beyond the last vertical connecting posts at each end, and the silk surface tapers back from this edge to the rear edge of the plane, and has several light ribs attached to it to give It stiffness. Thus the planes proper are 4 x 35 feet in size, which corresponds to a supporting surface of 280 square feet, while the flexible rear edges, etc., bring this up to a total of 385 square feet, which is also the weight of the machine fully equipped. Of this, 185 pounds represents the weight of the machine alone, and 200 that of the engine and propeller, filled fuel and all tanks, etc. Mr. F. W. Baldwin, M. E., who operated the aeroplane in its initial test, weighed 185 pounds, so that the total weight was 570 pounds, or 1.48 pounds for each square foot of supporting surface — a loading that was sufficiently light to make it possible for the aeroplane to rise at a speed of about 25 miles an hour and lift over 20 pounds per horse-power.

In constructing this machine for the purpose of experiment, every effort was made to reduce the head resistance as much as possible, and it was with this idea in view that the planes were curved and brought nearer together at their ends (the spacing apart is 6½ feet at the center and but 4 feet at the ends), so that the connecting posts could be shortened. These posts are somewhat oval in cross-section, their greatest width being from one-fourth to one-third of the distance back from the front edge. The large center posts are 4 inches from front to back and 1 inch thick; the next posts on either side are slightly smaller; and so on to the end ones, which are 1½ inches from front to back and have a maximum thickness of ½ inch.

The surfaces themselves are made of silk and contain pockets, in which are placed the curved, laminated wood strips extending from the front to the rear edge and giving the surfaces their curved form. Above each pair of posts a T-shaped wood strip extends from front to back, and helps to strengthen the structure. The spacing of the vertical posts also decreases from the center outward. The two center posts at the front and rear edges are about 22 inches apart. The first post on either side of these two is 6½ feet away, while the spacing between this and the next post is 5½ feet, and from here to the outer post about 5. The planes are connected together with diagonal guys of the finest piano wire procurable. They are trussed in both a vertical and horizontal direction.

The horizontal rudder, which is 8 feet long by 2 feet wide, is located at the front end of a suitable framework, which projects out 5 feet from the forward center posts. This framework is covered with silk in order to lessen the head resistance. The rudder is steadied at each end by rods, which run back to the planes. It is pivoted on a horizontal axis, and is operated by a vertical lever extending an equal distance above and below it and located at its center. A wire runs from one end of this lever around a pulley in the body framework, and back to the other end of the lever. Attached to the pulley is a small operating lever for turning the same and thus maneuvering the horizontal rudder. This rudder is worked by the left hand of the aviator, while the vertical rudder is operated in a similar manner by a lever convenient to the aviator’s right hand. The tail of the aeroplane consisted of but a single horizontal surface located 12 feet back of the rear edges of the planes. The dimensions of this tail were 14 feet 10 inches long by 3 feet wide, i.e., in a fore-and-aft direction. It was carried upon two long bamboo poles, which ran back horizontally from the lower plane, and which were well braced by other bamboo poles extending to the upper planes, and connected to the lower poles by spruce posts. This horizontal tail was also trussed on its under side to a vertical post, upon which was placed the vertical rudder.

Despite this trussing, the pressure upward against the tail was so great as to cause it to buckle on one side while the aeroplane was in the air, the result being that the machine veered sharply to the same side and landed, sliding sidewise on the ice and breaking one of the outer runners and its supporting post. The motor employed was an 8-cylinder Curtiss air-cooled engine of 40 horse-power. This engine was mounted on horizontal wood beams connecting the front and rear large center posts. It carried a light bicycle wheel on its front end as a flywheel, while the 6-foot propeller was mounted directly on the rear end of the crankshaft. The pitch of this propeller was 4 feet, and the number of revolutions per minute that it made while the aeroplane was in flight was probably in the neighborhood of 1,200. With the aeroplane held stationary and the motor running, a thrust of 130 pounds was obtained at about 1,000 R.P.M. The lower plane was notched at its rear edge in the center, to allow of the propeller revolving.

The 40-horse-power motor used had a bore and stroke of 35/8 and 3¼ inches respectively. This engine develops its full power at about 1,800 R.P.M., while at the speed at which it ran during the flight (viz., 1,200 R.P.M.) it developed only about 25 horse-power. The weight of this engine complete, without accessories, is but 145 pounds, while with a separate carburetor of 14 ounces weight upon each cylinder, and with the combined gasoline and all tank shown as well as including the propeller, the total weight was but 200 pounds. The engine had been thoroughly tested, driving a propeller and running the motor ice-boat illustrated in our last issue.

The idea of mounting the aeroplane upon runners and testing it upon the ice seems to be an excellent one, and to offer several advantages. Besides the two main runners of substantial construction, the next to the last vertical post at the rear of the surfaces was prolonged downward and fitted with a runner also, for the purpose of steadying the machine and keeping it on a level keel. A runner was also fitted to the vertical rudder post, but was subsequently removed.

Owing to the warm weather and the melting of the ice on Lake Keuka, near Hammondsport, N.Y., where the test was held, it was feared that it would be impossible to try the machine. Fortunately, however, a slight cold snap gave the experimenters a chance to make the trial; and on the 12th instant, upon its first test, the aeroplane flew a distance of 318 feet 11 inches, and apparently showed good stability. After running 200 feet, the machine rose to a height of 15 feet, and the trial could have been continued and made much longer had the horizontal tail not been damaged. The chief point to be noted is that no difficulty was experienced in getting up in the air with this machine, and in all probability in the near future it will be possible to make much more extended flights.

The Aerial Experiment Association, and especially those members who have been active in the construction of this new aeroplane, deserve great credit for designing and building a heavier-than-air machine that was able to fly at the first attempt, and we feel sure that in due time some valuable results will be obtained from the systematic experiments being carried on by this association. In the current issue of the SUPPLEMENT we have published a description of the experiments made by the association with Dr. Bell’s tetrahedral kite last fall. While the results were encouraging, it was not deemed wise to attempt to fit a motor to the tetrahedral cell aeroplane, so the latter was discarded for the time being, and experiments were begun with the usual two-surface type of aeroplane, the result being as detailed above.

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