The US Air Force Research Laboratory's (AFRL) third test flight of the Boeing/Pratt & Whitney Rocketdyne X-51A Waverider hypersonic test vehicle on 14 August has ended in failure.
Though the test article was successfully launched from a Boeing B-52 bomber near Point Mugu, California, the vehicle developed a fault after only 16s of flight - before the X-51A separated from its rocket booster. When the X-51A did separate from the booster rocket 15s later, the USAF says it could not maintain control of the vehicle due to a faulty control fin. The vehicle subsequently crashed.
US Air Force
"It is unfortunate that a problem with this subsystem caused a termination before we could light the Scramjet engine," says Charlie Brink, the AFRL's X-51A programme manager. "All our data showed we had created the right conditions for engine ignition and we were very hopeful to meet our test objectives."
The USAF says "this particular control subsystem had proven reliable in the previous two flights of the X-51A including the historic May 2010 flight when the Waverider flew for more than three minutes at Mach 4.88 under scramjet power - nearly five times the speed of sound."
Programme officials will now have to evaluate exactly what went wrong. The USAF does have a spare X-51A vehicle remaining in its inventory, but AFRL officials have not yet decided if they will launch it.