Stability of Aeroplanes.

(Washington, Government Printing Office, 1915). 8vo. As extracted from "the Annual Report of the Smithsonian Institution". A fine and clean copy. Pp. 209-216.

First printing of Orville Wright's speech on the longitudinal equilibrium, or how to keep the stability of aeroplanes, thus being one of the very first manuals on how to fly an aeroplane. "Although in learning to fly the beginner finds most difficulty in mastering the lateral control, it is his lack of knowledge of certain features of the fore-and-aft equilibrium that leads to most of the serious accidents". (From the introduction to the present speach).

The Wright brothers were early on aware of the importance of longitudinal control. Most of the early airplanes - the ones that could actually lift off ground - had the decisive flaw of having bad, in some cases non-existing, longitudinal control which eventually caused the airplanes to crash.
In the summer of 1910, the Wright Company introduced what would become their most popular aircraft - the Wright Model B. The Model B was a pusher biplane with wing warping to control roll, like their earlier aircraft. But unlike earlier aircrafts it also had a conventional tail assembly, which gave it better longitudinal stability, and it rested on wheels rather than skids, doing away with the need to launch the aircraft from a rail. This model was produced from 1910 through 1914. In 1911 the U.S. Congress made its first appropriation for military aviation. Four airplanes were ordered and numbers 3 and 4 were Wright Model B's. Both were accepted at Fort Sam Houston, Texas on April 17, 1911.

The two brothers were also investigating automatic stability systems. They devised a mechanism that could sense changes in attitude and longitude which would make compensating adjustments to keep the aircraft flying evenly in the desired direction. It consisted of a pendulum, which sensed and controlled roll or yaw, and a vane, which sensed the aircraft's pitch. They applied for a patent for this automatic stabilizing system on February 8, 1908.

"The culmination of the Wrights’ achievements came with Wilbur’s two flights at New York in 1909. On 29 September, taking off from and landing at Governors Island, he made a circuit of the Statue of Liberty; on 4 October he flew a twenty-one-mile course to Grant’s Tomb and back. After their triumph the brothers quietly turned to teaching others to fly and to directing the Wright Company. They now had many imitators and rivals, and were forced to defend their pioneer patent in the courts." (DSB).

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