Francis Herbert Wenham

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Francis Herbert Wenham (1824-1908) was an early aviation scientist and founding member of the Aeronautical Society of Great Britain. As an engineer he worked on various aspects of propulsion. In 1856, Wenham made a steamboat expedition up the Nile river with photographer Francis Firth.[1] He also worked on photography, microscopes, and binoculars.

In 1866, Wenham secured Patent GB-1866-1571 for an aircraft with multiple parallel planes, and gave an influential lecture on lift and air resistance at the first meeting of the Aeronautical Society. Throughout his career, he emphasized the efficiency of using long and narrow wings (to maximize lift and minimize weight).[2]

He is credited with inventing the wind tunnel, which he used to test his inventions.[3] He was supported in this endeavor by the Aeronautical Society, which created a subscription fund to gather "data on which a true science of aeronautics can be founded". John Browning of Penn's Marine Engineering Works, Greenwich, was hired to construct the apparatus, using a steam-driven fan. A balance and springs were included to allow the experimenter to measure lift and drag of the test object. Wenham's tests mostly dealt with flat planes—aerodynamically inefficient compared with natural wings or later airfoil designs.[4] Using the wind tunnel, Wenham provided experimental evidence for a crucial revision to Newtonian doctrine, demonstrating that air resistance for a plate moving through fluid varies in proportion not to the square of the sine of its angle with the movement vector, but simply to the sine itself.[5]

References

  1. Bill Jay, "Up the Nile with Francis Frith: Francis H. Wenham, 1824-1908", British Journal of Photography, 8 January 1982.
  2. John D. Anderson, Jr.,A History of Aerodynamics: And Its Impact on Flying Machines , p. 121
  3. Donald D. Baals and William R. Corliss, "Whirling Arms and the First Wind Tunnels" in Wind Tunnels of NASA, 1981.
  4. Hallion, 2003, pp. 116–117.
  5. Hallion, 2003, pp. 102–103. "Interpretation of one of Newton's propositions in his landmark Principia Mathematica indicated that in calculating the resistance of a plate set in a flow, one had to square the sine of the angle formed by the plate and the relative flow. Fortunately this concept, the so-called Newtonian sine-squared law proved incorrect: the resistance force acting on the plate is proportional to the sine of the angle, not the square of the sine of the angle. Squaring the sine implied drastic increases in drag as the angle of attack increased. If true, this would have demanded construction of totally impractical flying machines having enormous wings that could furnish the requisite lift for an airplane only while operating at minimal angles of attack. Hence it would have called into question whether a successful airplane could ever be built. After further examining Newton's work, later researchers fortunately recognized the error, realizing that wings could operate quite well at modest angles of incidence, and Francis Wenham experimentally disproved this bogus "law" in his first wind-tunnel tests. Nevertheless, it continued to haunt aeronautics even into the early twentieth century, used by ill-meaning critics to assert flight's 'impossibility'.

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