Area Rule of High-Speed Aircraft Design
Invented by Richard T. Whitcomb, Class of 1943
In 1951, while working for the National Advisory Committee for Aeronautics (the forerunner of NASA), Whitcomb set out to learn why airplanes experienced more drag than conventional theory suggested they should when flying at transonic speeds (faster than sound).
He conducted a series of tests in the transonic wind tunnel at Langley Research Center in Virginia. While puzzling over the photos from those tests, he made a breakthrough that would fundamentally change the way high-speed aircraft were designed. His discovery led to his formulation of the Area Rule, which says that drag at high speeds is a function of an airplane's total cross-sectional area (essentially, the thickness of the fuselage). Because projections from the fuselage increase a plane's cross section, narrowing the fuselage where the wings and tail assembly attach reduces drag.
He tested a model with a pinched-waist design and found that it behaved exactly as he predicted; the model is now in the Smithsonian's National Air and Space Museum. The idea was soon tested for first time on a real plane: the Convair YF-102, a new delta-winged jet fighter that had not performed well at transonic speeds. The plane was lengthened and given the now-famous "Coke-bottle" fuselage; in the words of a test pilot, the redesigned plane "slipped right past the sound barrier and kept on going."
Whitcomb also developed the supercritical wing, which has a blunted leading edge, a flattened top and a trailing edge that curves downward. By delaying the onset of shock waves that appear on the upper portions of wings at high speeds, the design enables military aircraft and commercial jetliners to fly faster and more efficiently. Winglets, another Whitcomb invention, are airfoils that extend at an angle from the ends of wings. By reducing wingtip vortices that can cause drag and decrease lift, they produce greater fuel efficiency. These and other accomplishments have earned Whitcomb numerous honors, including the Collier Trophy, aviation's highest award.
For more information and a video on Richard T. Whitcomb, view this NASA page.