A second test of a hypersonic unmanned aircraft failed Thursday when contact was lost shortly after takeoff, the Defense Advanced Research Projects Agency said. No details were given.

A Minotaur IV Lite rocket carrying the Falcon Hypersonic Technology Vehicle 2 lifted off Thursday morning from Vandenberg Air Force in California and successfully released the aircraft, DARPA said.

The glide mission was to have lasted about 30 minutes, but it seems the HTV failed once again, despite the tweaks DARPA made after the first launch in April 2010 went awry. That aircraft crashed into the Pacific Ocean just nine minutes after takeoff and was never recovered.

Before Thursday's attempt, DARPA said it would not build another Falcon HTV should it fail again.

The Falcon HTV is an unmanned aircraft that was billed as flying at Mach 20 -- 20 times the speed of sound, up to 13,000 miles per hour. It was said to be fast enough to travel from Los Angeles to New York in just 12 minutes and withstand temperatures hotter than the melting point of steel.

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