Hypersonic aircraft crashes on test flight

A hypersonic aircraft billed as the "world's fastest plane" has crashed into the Pacific Ocean after engineers lost contact with it, according to a US defence agency.

The unmanned Falcon HTV-2, which is designed to travel 22 times faster than a commercial airliner at speeds of up to 13,000mph, was just nine minutes into a test flight on Thursday when, according to the plane's operators, the Defence Advanced Research Projects Agency, officials lost contact with it.

The agency is developing the aircraft with the capability to strike any part of the globe with a conventional warhead within one hour. It will travel at 20 times the speed of sound.

A rocket launched from an air-force base in California carried the Falcon HTV-2 to the edge of space for this flight, its second so far. Engineers also lost contact with the aircraft on its first test flight in 2010.

"We know how to insert the aircraft into atmospheric hypersonic flight," Air Force Major Chris Schulz of Darpa said. "We do not yet know how to achieve the desired control during the aerodynamic phase of flight. It's vexing."