Sweepback

Sweepback refers to a wing planform in which the wing’s leading edge is angled backward from the root toward the tip. The amount of sweep is described by the sweep angle, typically measured relative to a line perpendicular to the airplane’s fuselage. Sweepback can be applied to the entire wing or only to portions of it (cranked arrow designs).

The primary aerodynamic purpose of sweepback is to improve performance at high speeds. By reducing the component of airflow normal to the wing at transonic and supersonic speeds, sweepback delays the onset of shock-induced drag rise and increases the aircraft’s critical Mach number. This allows heavier, faster aircraft to operate efficiently. However, swept wings reduce effective wing area for a given span, raise induced drag at low speeds, and can alter stall behavior, making the wingtips more prone to stalling if not properly managed. Design features such as twist, tailored airfoils, leading-edge extensions, and high-lift devices are often used to mitigate these effects and preserve handling characteristics.

Variations include fixed swept wings, cranked-arrow planforms, and variable- or swing-wing configurations. Swing-wing aircraft, such as the F-14 Tomcat, Panavia Tornado, and B-1 Lancer, change sweep angle in flight to optimize performance across speed ranges. The concept has informed the design of many jet transports and fighters since the 1950s.

History: the idea was first analyzed by Adolf Busemann in the 1930s, with practical adoption on military and civilian jets in the postwar era as transonic speeds became common.