Winglets

The initial theoretical concept goes back to times before even the Wright Brothers first took to the skies in 1905, but it was picked up and developed by Richard T. Whitcomb of NASA after the 1973 oil crisis � in order to reduce fuel consumption. The first tests were carried out in 1979/80 in cooperation with the U.S. Air Force. At almost the same time, but independent of any U.S. military organization, a private jet producer, LearJet exhibited a prototype in 1977: the LearJet 28 that featured the first winglets on a jet and a production aircraft. Flight tests made with and without winglets showed that the winglets increased range by about 6.5 percent and also improved directional stability for the LearJet- these two factors are the major reasons behind using this facility at any fixed wing aircraft ever since.

WINGTIP FENCES are a special variant of winglets, that extend both upward and downward from the tip of the wing.

BLENDED WINGLETS (the real �Winglets�) are the most popular winglet type, leveraged by Airbus, Boeing, Embraer, Bombardier but also by Russian Tupolev and Iljushin. Blended winglets were first introduced on the McDonnel Douglas MD-11 aircraft in 1990 with launch customer Finnair (it also features a smaller winglet at the bottom side of the wing).

RAKED WINGTIPS are the most recent winglet variants (they are probably better classified as special wings, though), where the tip of the wing has a higher degree of sweep than the rest of the wing.

As you can see, wingtips/winglets have developed and changed very much over the last 30 years, but are becoming the standard, which is not proven better by anything else than the wing designs of future aircraft by the largest airplane-makers that feature a built-in winglet at the tip of their new, revolutionary wings.

For the entire article and information see Airline World