page_title: Variable-sweep wing
section_title: Origins
hierarchical_section_title: Variable-sweep wing / History / Origins
caption_attribution_description: English: General Dynamics F-111E "Aardvark"
context_page_description: A variable-sweep wing, colloquially known as a "swing wing", is an airplane wing, or set of wings, that may be swept back and then returned to its original straight position during flight. It allows the aircraft's shape to be modified in flight, and is therefore an example of a variable-geometry aircraft.
  A straight wing is most efficient for low-speed flight, but for an aircraft designed for transonic or supersonic flight it is essential that the wing is swept. Most aircraft that travel at those speeds usually have wings with a fixed sweep angle. These are simple and efficient wing designs for high speed flight, but there are performance tradeoffs. One is that the stalling speed becomes rather high, necessitating long runways. Another is that the aircraft's fuel consumption during subsonic cruise is higher than that of an unswept wing. These tradeoffs are particularly acute for naval carrier-based aircraft. A variable-sweep wing allows the pilot to use the optimum sweep angle for the aircraft's current speed, slow or fast. The more efficient sweep angles available offset the weight and volume penalties imposed by the wing's mechanical sweep mechanisms.
context_section_description: The earliest use of variable sweep was to trim the aeroplane for level flight. The Westland-Hill Pterodactyl IV of 1931 was a tailless design whose lightly swept wings could vary their sweep through a small angle during flight. This allowed longitudinal trim in the absence of a separate horizontal stabiliser. The idea would later be incorporated in Barnes Wallis's wing controlled aerodyne.
  In World War II German researchers discovered the advantages of the swept wing for transonic flight, and also its disadvantages at lower speeds. The Messerschmitt Me P.1101 was a research prototype developed to investigate the benefits of varying wing sweep. Its sweep angle could only be changed on the ground. However it was not yet completed when the war ended.
caption: F-111E on display at the Museum of Aviation, Robins AFB, United States
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