Boeing's X-51 WaveRider has made aviation history by completing the longest ever supersonic* combustion ramjet-powered flight. The unmanned aerial vehicle (UAV) flew for almost three and a half minutes in the skies off the southern California coast on Wednesday, reaching an altitude of about 70,000 feet and hitting hypersonic (Mach 5) speeds.

The X-51 WaveRider scramjet (supersonic combustion ramjet) is being developed for the Air Force Research Laboratory and the Defense Advanced Research Projects Agency (DARPA) by Boeing and Pratt & Whitney Rocketdyne.

The goal of the program is to create a free-flying, scramjet-powered vehicle capable of operating continuously on jet fuel and achieving continuous hypersonic speeds - a challenge which program officials compare to "lighting a match in a hurricane and keeping it burning."

During its first autonomous flight, the X-51 was launched at 50,000 feet from under the wing of a B-52H Stratofortress before being accelerated to Mach 4.8 using a solid rocket booster from a U.S. Army tactical missile. The rocket then jettisoned and aircraft then flew under the power of its powered by its Pratt & Whitney Rocketdyne scramjet motor for around 200 seconds, burning a mix of ethylene and JP-7 jet fuel.

The flight is considered the first use of a practical hydrocarbon fueled scramjet in flight and smashes the previous record for a scramjet burn in a flight test was 12 seconds in a NASA X-43, which has achieved speeds speeds of Mach 9.8, or 7,000 mph.

"We are ecstatic to have accomplished most of our test points on the X-51A's very first hypersonic mission," said Charlie Brink, a X-51A program manager with the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio. "We equate this leap in engine technology as equivalent to the post-World War II jump from propeller-driven aircraft to jet engines."

While the flight is being hailed as a success, the terabytes of telemetry data transmitted by the X-51A to both ground systems and an airborne U.S. Navy P-3 Orion is yet to be analyzed.

"This is a new world record and sets the foundation for several hypersonic applications, including access to space, reconnaissance, strike, global reach and commercial transportation," said Joe Vogel, Boeing director of Hypersonics and X-51A program manager.

The Air Force officials plans to fly the three remaining X-51A flight test vehicles this year on virtually identical flight profiles.

* Supersonic speeds are defined as being above the speed of sound (Mach 1).

Via Boeing and USAF.

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