2004: In its final flight, NASA’s B-52 #008 launch vehicle, the oldest plane in the USAF inventory, carried the X-43A mounted on a Pegasus booster into the air. The X-43A then broke its 4,780 MPH record achieved on 27 March. After separating from a Pegasus booster rocket at 110,000 feet, the scramjet engine accelerated the X-43 to 7,000 mph (Mach 9.8). With this flight, the Dryden Flight Research Center validated the operation of the supersonic-combustion ramjet, powered by liquid hydrogen and atmospheric oxygen.
