Swept Wing

A swept wing is a wing planform favored for high subsonic jet speeds first investigated in Germany from 1935 onwards until the end of the Second World War. Since the introduction of the MiG-15 and North American F-86 which demonstrated a decisive superiority over the slower first generation of straight-wing jet fighters during the Korean War, swept wings have become almost universal on all but the slowest jets (such as the A-10). Compared with straight wings common to propeller-powered aircraft, they have a "swept" wing root to wingtip direction angled beyond (usually aftward) the spanwise axis. This has the effect of delaying the drag rise caused by fluid compressibility near the speed of sound as swept wing fighters such as the F-86 were among the first to be able to exceed the speed of sound in a slight dive, and later in level flight.

Unusual variants of this design feature are forward sweep, variable sweep wings and pivoting wings. Swept wings as a means of reducing wave drag were first used on jet fighter aircraft, although many propeller-driven aircraft now also use the wing plan.

The angle of sweep which characterizes a swept wing is conventionally measured along the 25% chord line. If the 25% chord line varies in sweep angle, the leading edge is used; if that varies, the sweep is expressed in sections (e.g., 25 degrees from 0 to 50% span, 15 degrees from 50% to wingtip). Angle of sweep equals 1/2.