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Technicalities: Rules to Fly By

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Gemini Sparkle

Key Takeaways:

  • Richard Whitcomb significantly influenced modern aircraft design through innovations such as the winglet, supercritical airfoil, and most notably, the transonic area rule.
  • Whitcomb's transonic area rule established that an airplane's wave drag near the speed of sound depends on its overall volume distribution, not just individual component shapes, leading to "Coke bottle" fuselage designs for drag reduction.
  • While Whitcomb is credited with the area rule's independent discovery and application, the core concept was first patented in Germany by Otto Frenzl in the mid-1940s; its principles remain vital in modern aircraft design for optimizing volume distribution.
  • The article distinguishes Whitcomb's transonic area rule, which addresses wave drag at high speeds, from the "poor man's area rule," a subsonic concept for minimizing interference drag by staggering components and smoothing flow channels.
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Aerodynamicists seldom earn long obits in the New York Times, but Richard Whitcomb, who died last Oct. 13 at 88, did. He left a conspicuous imprint on the design of modern airplanes. He was responsible for the winglet, the supercritical airfoil — which he designed not on a computer, as would be done today, but by laboriously reshaping a wind tunnel model with auto body filler — and the transonic area rule.

The story of the transonic area rule involves one of those “eureka moments” that we have learned to admire in all great tales of invention and discovery. It happened at the Langley, Virginia, headquarters of the National Advisory Committee for Aeronautics, which would become NASA a few years later. Whitcomb had been ruminating about the rapid increase in drag that airplanes experienced as they approached the speed of sound. He possessed uncommon insight into the behavior of air, a gift that must have been in part a happy congenital mixture of spatial visualization and kinesthetic empathy and in part acquired, as can people who, like Leonardo da Vinci, for some reason or other find rivers and streams, blowing leaves, smoke and clouds worthy of special attention. But a good instinct for subsonic aerodynamics does not serve at supersonic speeds. The supersonic domain, in the phrase a British novelist used about the past, “is a foreign country; they do things differently there.”

Peter Garrison

Peter Garrison taught himself to use a slide rule and tin snips, built an airplane in his backyard, and flew it to Japan. He began contributing to FLYING in 1968, and he continues to share his columns, ""Technicalities"" and ""Aftermath,"" with FLYING readers.

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