Samuel Pierpont Langley - America's first aeronautical engineer

Author:

Anderson, Jr. John1

Affiliation:

1. National Air and Space Museum, Washington, DC

Publisher

American Institute of Aeronautics and Astronautics

Reference32 articles.

1. The most substantive data from Langley's plane-dropper tests is that wings with high aspect ratio produced more lift than wings with low aspect ratio. This is clearly seen in Fig. 3, taken from Exoeriments in Aerodvnamics, Here, the time required to fall 4 feet is plotted versus the horizontal velocity for three plates of equal weight and surface area but different aspect ratio. Clearly, at any given velocity, the higher the aspect ratio, the longer is the falling time. Although Langley was not the first to appreciate the aerodynamic efficiency of highaspect-ratio wings (Francis Wenham in England in 1866 was the first to point out this effect), he was the first to produce an organized set of definitive experimental data that clearly proved the superiority of such wings. Moreover, as we will discuss later, Langley later put this data to use in the design of his aerodromes. Note that the highest aspect ratio model shown in Fig. 3 is that consisting of two 18 x 4 inch planes; here, the aspect ratio of each plane is 4.5 - a fairly high value for the state-of-the-art at that time. Influenced by these results, Langley later designed his successful aerodrome #5 with a relatively high aspect ratio of 5. Lanalev's Power Law

2. This conclusion flies in the face of intuition, which is why Langley labeled it as "paradoxical0022. It was considered to be misleading at best by some contemporaries, and outright wrong by others. Crouch' states that Lilienthal and the Wright brothers rejected this conclusion outright. In a meeting of the British Association for the Advancement of Science at Oxford in August 1884, Langley presented a short paper summarizing his work and conclusions; he was criticized and taken to task by both Lord Kelvin and Lord Rayleigh - formidable opposition to say the least. Indeed, Langley has been derided for his power law to the present day.

3. However, it had already became clear to Langley that, to .convince the rest of the world that his conclusion was correct, he had to do more than conduct laboratory experiments. Indeed, during Langley's participation in the August 1894 meeting of the British Association for the Advancement of Science at Oxford, Lord Rayleigh commented that the ultimate proof of the validity of Langley's aerodynamic data would be "if he.succeeded in doing it (flying) he would be (proven) right." Rayleigh's comment was support for activities.that Langley already had underway - activities aimed at the design, construction, and flying of an actual heavierthan-air machine. Part I of the Lanalev Memoir on Mechanical Fliahtg published in 1911 - five years after Langley's death - was written by Langley in 1897. In the introduction to Part I, Langley wrote:

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1. Aerial Robotics;Springer Handbook of Robotics;2008

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