X-43A Hypersonic Experimental Vehicle artist concept. X-43A Hypersonic Experimental Vehicle
NASA's X-43A hypersonic research aircraft became the first scramjet-powered aircraft to successfully operate in flight, in 2004.
NASA flew two integrated scramjets (the engine and airframe are necessary for each other in order to operate) in 2004, the first to a speed just shy of Mach 7, the second to a speed just under Mach 10. The most significant detail about the flights-apart from the successful operation of the engines themselves-was that on the first flight the engine developed enough thrust to overcome drag, and on the second, it developed enough thrust to cruise at Mach 10.
Unlike rockets, which must carry both their fuel and oxidizer, scramjets carry only fuel; they take oxygen from the atmosphere. This reduces weight, raising payload or increasing capability.
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