Los Angeles - The US Air Force began a flight test Tuesday for a hypersonic airplane capable of reaching six times the speed of sound, a military spokesman said.
Edwards Air Force Base spokesman John Haire told the Washington Post that the B-52 bomber carrying the experimental aircraft had taken off after 10 am in California, but gave no further details about the flight.
It was the third known test-flight for the X-51A Waverider, so named because it rides the shock waves caused by its high speed to reach even higher speeds.
Built by aerospace giant Boeing, and featuring a Scramjet engine built by California-based Pratt & Whitney, the nearly wingless craft achieves its incredible speeds by injecting hydrogen into the air stream rushing through its engines, with the resulting hot gases providing thrust.
Plans for the test flight had called for the Waverider to be dropped from its bay under the B-52's wing. A rocket booster was due to accelerate the aircraft to more than 7,000 kilometres per hour, before the Scramjet accelerates the craft to almost 10,000 kilometres per hour for a duration of five minutes.