X-51A WaveRider's third flight foiled by cruiser control fin

The much-anticipated third flight of the X-51A WaveRider hypersonic technology demonstrator ended prematurely due to a control fin failure, potentially causing the programme to miss its goal of reaching Mach 6.

The aircraft was launched from a US Air Force (USAF) B-52 Stratofortress over Point Mugu Naval Air Warfare Center Sea Range on 14 August and the solid rocket booster fired as planned, said the USAF in a 15 August statement.

"However after 16 seconds, a fault was identified with one of the cruiser control fins. Once the X-51 separated from the rocket booster, approximately 15 seconds later, the cruiser was not able to maintain control due to the faulty control fin and was lost," the USAF said.

The aircraft serves as a test bed for new technology. It employs high-temperature materials, an airframe designed to 'ride' airwaves created by high-speed flight and an air-breathing hydrocarbon-fueled scramjet (supersonic combustion ramjet) engine.

A rocket booster is used to accelerate the vehicle to supersonic speeds and then the scramjet is engaged to reach hypersonic speeds greater than Mach 5.