Variable-Sweep Wing

A variable-sweep wing, commonly called a swing wing, is an aircraft wing that can change its sweep angle in flight, letting a straight, low-speed-efficient configuration sweep back into a high-speed, low-drag configuration for transonic or supersonic flight and then return, combining advantages that a fixed wing shape cannot offer across a full flight envelope. The British Westland-Hill Pterodactyl IV of 1931 was the earliest aircraft to vary its wing sweep, though only for trim control, and wartime Germany's Messerschmitt Me P.1101 studied variable sweep using ground-adjustable positions; the American Bell X-5 became the first aircraft to vary its wing sweep successfully in flight, and the General Dynamics F-111, entering service in the 1960s, was the first production aircraft built with variable-sweep wings. Development of new variable-sweep designs largely ceased after the 1980s as computer-controlled flaps and improved materials made fixed wings more practical for the same purposes, and the Soviet Tupolev Tu-160 of 1987 remains the last new variable-sweep design, though Russia resumed producing it in 2021.