supersonic

Supersonic refers to speeds greater than the speed of sound in the surrounding medium. The boundary is defined by Mach number, with Mach 1 equal to the speed of sound. In dry air at sea level, the speed of sound is about 343 meters per second (1,125 feet per second), but it varies with temperature and altitude. Supersonic flight generally ranges from Mach 1 to approximately Mach 5; speeds above Mach 5 are often called hypersonic.

When an object travels faster than sound, it generates shock waves and a sonic boom heard on the ground. Drag and stability change markedly in this regime, and the transonic region—near Mach 1—can include both subsonic and supersonic flows on the aircraft.

Design for supersonic flight seeks to minimize wave drag via slender bodies, area ruling, sharp noses, and swept or delta wings. Jet propulsion may use afterburners for high thrust, and materials must withstand skin heating at altitude. Notable examples include the Bell X-1, which first broke the sound barrier in 1947; the Concorde and Tu-144 as supersonic transports; and military fighters such as the F-4 and F-14.

Supersonic flight offers high speeds but entails higher fuel consumption, louder sonic booms, and environmental concerns. Practical commercial supersonic travel faced regulatory and economic hurdles, so today most supersonic work is military or research-focused, with ongoing efforts to reduce noise and emissions.