Military

Boeing to Flight Test X-51A UAV

By Tish Drake | May 24, 2010

The Boeing X-51A WaveRider unmanned aerial vehicle will make its first hypersonic flight test attempt from Edwards Air Force Base on Tuesday, the airframer announced last week.

The UAV, which will be released from a B-52, is expected to fly autonomously for five minutes -- powered by a supersonic combustion ramjet (scramjet) motor -- accelerate to about Mach 6 and transmit large amounts of data to ground stations before it splashes down into the Pacific and breaks up, as planned. There are no plans to recover the flight test vehicle, one of four built, Boeing said.

"In those 300 seconds, we hope to learn more about hypersonic flight with a practical scramjet engine than all previous flight tests combined," said Charlie Brink, X-51A program manager with the Air Force Research Laboratory's Propulsion Directorate at Wright-Patterson Air Force Base. The longest previous hypersonic scramjet flight test, performed by a NASA X-43 in 2004, was faster, but lasted only about 10 seconds and used less logistically supportable hydrogen fuel.

The May 25 attempt will be the only hypersonic flight attempt this fiscal year, a change from the original test plan, which was to fly once in December 2009 and three more times in 2010. A combination of factors, including high demand for flight-test and range assets such as the B-52, contributed to the pause, according to Boeing.

"This is an experimental X-plane and it's a complicated test. We knew the original schedule was aggressive and we would need to be flexible," said Brink. "It's also expensive to keep a staff of engineers and support staff at the ready and then not be able to fly when supporting assets aren’t available. So we elected to make only one hypersonic try this spring and then pause for a few months to conserve funding."

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