LOS ANGELES — An unmanned experimental aircraft failed during an attempt to fly at six times the speed of sound in the latest setback for hypersonic flight. The X-51A Waverider was designed to reach Mach 6, or 3,600 mph, after being dropped by a B-52 bomber off the Southern California coast on Tuesday. Engineers hoped it would sustain its top speed for five minutes, twice as long as an X-51A has gone before.
But the Air Force said Wednesday that a faulty control fin prevented it from starting its exotic scramjet engine and it was lost. The Waverider successfully detached from the B-52 and fired the rocket booster as planned. Then its scramjet engine was supposed to take over as it attempted to climb to Mach 6, but that never happened. Fifteen seconds after separating from the rocket booster, the Waverider lost control, preventing a test of the scramjet engine. |