NASA Supercritical Wing - Winglets, Dryden history gallery

In the late 1970s Richard Whitcomb of Langley Research Center, Hampton Va., developed winglets, which reduced drag on aircraft wings. They were the third of his major aeronautical discoveries. In the 1960s, he had originated the supercritical wing, an airfoil shape that reduced drag at speeds just below Mach 1. In the 1950s, Whitcomb developed the area rule concept, discovering that a narrowing in the fuselage over the wing reduced high-speed drag at transonic speeds. Winglets typically have supercritical airfoils and serve as end plates on the wing that stop the spanwise airflow down the wing while diminishing wingtip vortices. They also "fool" the wing into behaving as if it had a longer span, making the wing more efficient without the performance penalties of a longer wing. Whitcomb selected the best winglet shape for flight tests on a KC-135 tanker. These were large vertical fins installed on the tanker's wing tips. The modified KC-135 was flight-tested at Dryden during 1979 and 1980 and the data showed that the winglets provided a 7 percent improvement in range over that of the standard KC-135. The economic advantage eventually led to adoption of winglets on light aircraft, business jets, airliners and heavy military transports. Winglets were also retrofitted on older aircraft. While the KC-135 winglets were large, subsequent designs were smaller and lighter. Whitcomb led a team of researchers to develop and test a series of unique geometric airfoil shapes, or wing designs, that could be applied to subsonic transport to reduce drag at high speeds. The result was the supercritical airfoil. Compared with a conventional wing, the supercritical wing is flatter on the top and rounder on the bottom with a downward curve at the trailing edge. Dryden research flights validated that aircraft using the supercritical wing see increased cruising speed, improved fuel efficiency (about 15 percent), and better flight range than those using conventional wings. As a result, supercritical wings are now common on most modern subsonic military and commercial transports. Photo Description F-8 Supercritical Wing aircraft flights demonstrated increased cruising speed, improved fuel efficiency of about 7 percent, and better flight range than those made with conventional wings. As a result, supercritical wings are now common on most modern subsonic commercial transports. NASA Photo
NASA Identifier: 299372main_EC73-3468_full