Aircraft designed to fly at six times the speed of sound

The Associated Press Published Wednesday, August 15, 2012 10:49AM EDT

U.S. Air Force, X-51A WaveRider, hypersonic flight

In this July 17, 2009 photo provided by the U.S. Air Force, an X-51A WaveRider hypersonic flight test vehicle is uploaded to an Air Force Flight Test Center B-52 for fit testing at Edwards Air Force Base. (AP / U.S. Air Force, Chad Bellay)

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EDWARDS AIR FORCE BASE, Calif. -- The Air Force planned a key test Tuesday of an experimental aircraft designed to fly at six times the speed of sound, or about 3,600 mph.

The unmanned X-51 WaveRider was expected to reach Mach 6 after it's dropped by a B-52 bomber and takes 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.

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.

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.