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A supercruising aircraft is able to cruise at supersonic speeds efficiently without the use of afterburners. The first turbine-powered aircraft to exceed Mach 1 in level flight without afterburners was the P.1 prototype of the English Electric Lightning, on August 4, 1954. Afterburners, which most military aircraft use to travel at supersonic speeds, are very inefficient compared to conventional jet engine operation due to the low pressures typically found in the exhaust section. Therefore, in general, an aircraft which can supercruise has greater endurance at supersonic speeds than one which cannot. Furthermore, without a requirement to carry such a large quantity of fuel, a supercruise-capable aircraft can have a more favourable fuel fraction, the proportion of the plane's overall mass which is devoted to fuel. Of these aircraft, only the civilian Concorde and Tupolev actually spend most of their cruising time at supersonic speeds, and that many of the fighters listed can only marginally exceed the speed of sound without afterburner and may only be able to do so without an external weapons load. Concorde operationally used reheat (afterburners) in the transonic flight regime, although in fact was capable of just barely reach its top speed without (but not usefully due to the fuel use penalty of spending longer at high-drag transonic speeds). For military aircraft, the F-22 Raptor and Eurofighter Typhoon's supercruise capabilities, by contrast, are touted as a major performance advantage over other fighters. Even so, supercruising uses much more fuel to travel the same distance than at subsonic speeds: The Air Force Association estimates that use of supercruise for a 100 nautical mile dash as part of a mission would cut the F-22's combat radius from about 600 to about 400 nautical miles. However, this is still unconfirmed as the altitude and flight profile are classified (as are most of the F-22A's capabilities). There is no way to compare this with other aircraft; however, most aircraft using afterburner to fly at supersonic speeds will have exhausted their fuel supplies very rapidly. Another special case is the SR-71 spyplane. This aircraft's engines were designed for sustained and efficient operation at supersonic speeds using afterburners. This efficiency was mainly due to the higher operating speed of the aircraft. The afterburners acted essentially as ramjets and these types of engines achieve peak efficiency at around mach 3 due to the high compression ratio given by ram effect at these speeds. Aircraft with supercruise include:
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