The X-51A WaveRider hypersonic vehicle, powered by Pratt & Whitney Rocketdyne’s scramjet engine, achieved aviation history this week by making the longest-ever supersonic combustion ramjet-powered flight.
’This first test flight brings aviation closer than ever to the reality of regular, sustained hypersonic flight,’ said Curtis Berger, director of Hypersonic Programs, Pratt & Whitney Rocketdyne.
The X-51A programme is a collaborative effort between the US Air Force Research Laboratory, the Defense Advanced Research Projects Agency, Boeing and Pratt & Whitney Rocketdyne.
Charlie Brink, X-51A programme manager with the US Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, said: ’We equate this leap in engine technology as equivalent to the post-Second World War jump from propellers to jet engines.’
During its first flight, the unmanned WaveRider vehicle was carried beneath a US Air Force B-52 and dropped from an altitude of about 50,000ft over the Pacific Ocean, off southern California.
A solid rocket booster fired and propelled the cruiser to greater than Mach 4.5, creating the supersonic environment necessary to operate the engine.
The booster was then jettisoned and the Pratt & Whitney Rocketdyne SJY61 scramjet engine ignited, initially on gaseous ethylene fuel. Next, the engine transitioned to JP-7 jet fuel, the same fuel once carried by the SR-71 Blackbird.