An artist's conception of the X-43A Hypersonic Experimental Vehicle, or "Hyper-X" in flight.
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An artist’s conception of the X-43A Hypersonic Experimental Vehicle, or “Hyper-X” in flight. The X-43A was developed to flight test a dual-mode ramjet/scramjet propulsion system at speeds from Mach 7 up to Mach 10 (7 to 10 times the speed of sound, which varies with temperature and altitude).1998NASA Illustration by Steve Lighthill› X-43A Project Description