sweptback

Sweptback refers to a wing or other lifting surface whose edges are angled backward from the root toward the tips. In aviation, swept-back geometry is common on many jet aircraft and is sometimes described by the sweep angle, the angle between the wing’s leading edge and a line perpendicular to the aircraft’s longitudinal axis.

The primary aerodynamic rationale for sweep is to improve performance at higher subsonic and transonic speeds. By tilting the wing backward, the component of airspeed acting perpendicular to the leading edge is reduced, which delays the onset of shock waves and the associated drag rise as aircraft approach the speed of sound. However, sweep also lowers the wing’s maximum lift coefficient and can alter stall characteristics, often requiring a larger wing area or different tapering and twist to maintain acceptable low-speed handling. Structural considerations, such as increased bending and torsional loads, also influence sweep design.

Variants and related concepts include cranked-arrow wings, where the wing root and tip have different sweep angles to balance lift distribution and stall behavior, and variable-geometry or swing wings, which can change sweep in flight. Swing-wing configurations were used on several aircraft to optimize performance across a wide speed range, most famously on some military bombers and fighters.

Historically, swept wings were studied in the 1930s and 1940s, with early research credited to Adolf Busemann. They became standard on commercial jet airliners in the 1950s and 1960s, and continue to be a foundational concept in modern aerodynamics, sometimes complemented by advanced designs such as supercritical or natural-laminar-flow wings to optimize performance within swept configurations.