Unmanned Airplane to Reach 6 Times the Speed of Sound

The United States Air Force planned a key test Tuesday of an experimental aircraft designed to fly at six times the speed of sound, which is about 3,600 mph (6,000 kph).

The unmanned X-51 WaveRider was expected to reach Mach 6 after being dropped by a B-52 bomber and taking flight off the Southern California coast near Point Mugu. Engineers hoped the X-51 would sustain its top speed for five minutes, twice as long as it's gone before, NBC reported.

The B-52 took to the skies Tuesday, but no other information about the test flight was available, John Haire, a spokesman for Edwards Air Force Base in California, said in an email.

Public affairs officials at Wright-Patterson Air Force Base in Ohio, who are in charge of the X-51 development project, provided no updates either.

Last year, in its most recent test, the X-51 fell for about four seconds before its booster rocket ignited, but the aircraft failed to separate from the rocket and plunged into the ocean.

Designed by Boeing Co., the aircraft is intended to allow the Pentagon to deliver strikes around the globe within minutes.

Eventually, the X-51's hypersonic propulsion technology may be applied to civil aviation as well for such a speed would pull a trip from London to New York down to one hour.

"Is it going to happen in two or three years? No," Imperial College aeronautical engineer Paul Bruce told Britain's ITV News. "Could it happen in 10, 20 years? I think the answer is probably yes, if there's enough of a market there."