The trapezoidal or diamond wing is a high-performance wing configuration. It is a short (low aspect ratio) tapered wing having little or no overall sweep, such that the leading edge sweeps back and the trailing edge sweeps forwards. The trapezoidal design allows for a thin wing with low drag at high speeds, while maintaining high strength and stiffness. To date, all major aircraft to use this design have come from the United States.
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Early examples provided a solution to the problem of supersonic flight when engine power was limited. The wing of the Douglas X-3 Stiletto was extremely small and thin, giving low drag at supersonic speeds. The principle was adopted for various other X-planes and for Lockheed's widely-produced F-104 Starfighter high-speed, high-altitude interceptor. Lockheed used the design on many of its aircraft proposals in the 1950s, including the Lockheed CL-400 Suntan and early versions of their supersonic transport designs.
The small wing of the Starfighter was found to have good gust response at low level, providing a smooth ride at high subsonic speeds. Consequently the type was adopted for the ground-attack role, notably by the German Luftwaffe. However the small size of the wing also meant high take-off and landing speeds with minimal stability or control, and many pilots were killed during takeoff and landing accidents.
More recently, a larger and less highly loaded variant has been found to provide good all-round speed, load carrying and maneuvering characteristics for modern combat fighters such as the Lockheed F-22 Raptor and others. Its inherent light weight has also led to its adoption for the VTOL-capable F-35 Lightning II Joint Strike Fighter.