Variable-sweep Wing

A variable-sweep wing, colloquially known as a "swing wing", is an aeroplane wing that may be swept back and then returned to its original position during flight. It allows the aircraft's planform to be modified in flight, and is therefore an example of a variable-geometry aircraft.

Typically, a swept wing is more suitable for high speeds, while an unswept wing is suitable for lower speeds, allowing the aircraft to carry more fuel and/or payload, as well as improving field performance. A variable-sweep wing allows a pilot to select the correct wing configuration for the plane's intended speed. The variable-sweep wing is most useful for those aircraft that are expected to function at both low and high speed, and for this reason it has been used primarily in military aircraft.

A number of successful and experimental designs were introduced from the 1940s into the 1970s; however, the recent advances in flight control technology and structural materials have allowed designers to closely tailor the aero-dynamics and structure of aircraft, removing the need for variable geometry to achieve the required performance.