Supersonic aircraft

Aircraft that travels faster than the speed of sound

A supersonic aircraft is an aircraft capable of supersonic flight, that is, flying faster than the speed of sound (Mach 1). Supersonic aircraft were developed in the second half of the twentieth century. Supersonic aircraft have been used for research and military purposes, but only two supersonic aircraft, the Tupolev Tu 144 (first flown on December 31, 1968) and the Concorde (first flown on March 2, 1969), ever entered service for civil use as airliners. Fighter jets are the most common example of supersonic aircraft. The aerodynamics of supersonic flight is called compressible flow because of the compression associated with the shock waves or "sonic boom" created by any object traveling faster than sound. Aircraft flying at speeds above Mach 5 are called hypersonic aircraft.

The first aircraft to fly supersonic in level flight was the American Bell X 1 experimental plane which was powered by a thrust rocket powered by liquid oxygen and ethyl alcohol. Most supersonic aircraft have been military or experimental aircraft. Aviation research during World War II led to the creation of the first rocket and jet powered aircraft. Several claims of breaking the sound barrier during the war subsequently emerged. However, the first recognized flight exceeding the speed of sound by a manned aircraft in controlled level flight was performed on October 14, 1947 by the experimental Bell X 1 research rocket plane piloted by Chuck Yeager. The first production plane to break the sound barrier was an F 86 Canadair Sabre with the first supersonic woman pilot, Jacqueline Cochran, at the controls. According to David Masters, the DFS 346 prototype captured in Germany by the Soviets, after being released from a B 29 at 32800 ft (10000 m), reached 683 mph (1100 km/h) late in 1951, which would have exceeded Mach 1 at that height. The pilot in these flights was the German Wolfgang Ziese. On August 21, 1961, a Douglas DC 8 43 (registration N9604Z) exceeded Mach 1 in a controlled dive during a test flight at Edwards Air Force Base. The crew were William Magruder (pilot), Paul Patten (copilot), Joseph Tomich (flight engineer), and Richard H. Edwards (flight test engineer). This was the first intentional supersonic flight by a civilian airliner, and the only one ever performed by a civilian airliner other than the Concorde or Tu 144.]] A sonic boom is the sound associated with the shock waves created whenever an object traveling through the air travels faster than the speed of sound. Sonic booms generate significant amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear. The crack of a supersonic bullet passing overhead or the crack of a bullwhip are examples of a sonic boom in miniature. Sonic booms due to large supersonic aircraft can be particularly loud and startling, tend to awaken people, and may cause minor damage to some structures. They led to prohibition of routine supersonic flight over land. Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle the nuisance due to them may be reduced to the point that overland supersonic flight may become a practical option.

Supercruise is sustained supersonic flight of a supersonic aircraft with a useful cargo, passenger, or weapons load performed efficiently, which typically precludes the use of highly inefficient afterburners or "reheat". Many well known supersonic military aircraft not capable of supercruise can only maintain Mach 1+ flight in short bursts, typically with afterburners. Aircraft such as the SR 71 Blackbird are designed to cruise at supersonic speed with afterburners enabled. One of the best known examples of an aircraft capable of supercruise was Concorde. Due to its long service as a commercial airliner, Concorde holds the record for the most time spent in supercruise; more than all other aircraft combined.

Supersonic business jets (SSBJ) are a proposed class of small supersonic aircraft. None have yet flown. Typically intended to transport about ten passengers, SSBJs are about the same size as traditional subsonic business jets. Projects for both large scale and business jet (see lower) passenger supersonic and hypersonic airliners (Aerion SBJ, Spike S 512, HyperMach SonicStar, Next Generation Supersonic Transport, Tupolev Tu 444, Gulfstream X 54, LAPCAT, Reaction Engines LAPCAT A2, Zero Emission Hyper Sonic Transport, SpaceLiner, etc.) were proposed and now are under development.

Some supersonic strategic bombers, such as the Sukhoi T 4 are also capable of the reconnaissance role (although the Sukhoi remained a prototype). The Lockheed SR 71 Blackbird was specifically designed for the role, and was a larger development of the Lockheed A 12 reconnaissance aircraft which first flew in 1962.

Supersonic fighters and related aircraft are sometimes called fast jets. They make up the overwhelming majority of supersonic aircraft and some, such as the Mikoyan Gurevich MiG 21, Lockheed F 104 Starfighter and Dassault Mirage III, have been produced in large numbers. Many military supersonic fighters and similar aircraft of fourth and fifth generations are under development in several countries, including Russia, China, Japan, South Korea, India, Iran and the United States.