Variable-sweep wing

An aircraft wing whose angle of sweep changes in flight. Sweeping it back reduces drag at high speed; moving it forward improves low-speed lift and handling.

Wing sweep: The backward or forward angle of an aircraft wing’s leading edge relative to the fuselage. Variable-sweep designs alter this angle in flight to suit changing speed.
Grumman F-14 Tomcat: A U.S. Navy supersonic fighter whose wings automatically varied sweep across its flight envelope. Its automatic sweep system balanced carrier approaches with high-speed interception.
Messerschmitt P.1101: A late-World War II German jet prototype whose wing sweep could be adjusted on the ground. Its design helped inspire postwar American research into variable-sweep aircraft.
Fixed-wing aircraft: An aircraft supported by wings that remain fixed relative to its fuselage during flight. Fixed wings avoid the pivot hardware and structural penalties of changing sweep.
Quarter-chord sweep: The angle between an aircraft’s quarter-chord line and a line perpendicular to its longitudinal axis. This aerodynamic measure better predicts compressibility effects than leading-edge sweep alone.
General Dynamics F-111 Aardvark: A supersonic strike aircraft developed jointly by the United States Air Force and Navy. Its variable-sweep wings accommodated low-level penetration and high-speed flight.
Bell X-5: An experimental U.S. aircraft that demonstrated powered in-flight wing-sweep changes. It established that a pivoting wing could move safely between sweep settings during flight.
Delta wing: A triangular wing planform commonly used on high-speed aircraft. Delta wings achieve high-speed performance without movable sweep mechanisms.
Sweep theory: Aerodynamic theory describing how wing sweep changes airflow components perpendicular to a wing’s leading edge. It explains why sweeping a wing delays the rise in drag near transonic speeds.
Panavia Tornado: A European variable-sweep combat aircraft designed for low-level strike, air defense, and reconnaissance. Its mission flexibility depended on adapting sweep to different speeds and payloads.

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