The arrowhead-shaped unmanned Falcon Hypersonic Technology Vehicle 2 (FHTV2)

A test flight of the 'world's fastest plane', the HTV-2, has ended in disaster after the vehicle crashed into the Pacific Ocean, it has been reported.

The U.S. military's Falcon HTV-2 - which travels 22 times faster than a commercial airliner and is rumoured to be capable of reaching any target in the world in less than an hour, was launched but a few minutes after it took off, the U.S. military lost contact with the aircraft.

The Falcon Hypersonic Test Vehicle 2 (HTV-2) - started a test flight from atop a Minotaur IV rocket on Thursday, before officials lost contact with the aircraft.

According to officials, the HTV-2, designed to be the fastest ever after aircraft, travelling at 13,000mph (21,000km/h), left Vandenberg Air Force Base in California and managed to separate from its launch vehicle successfully.

However while it was next expected to separate from its rocket near the top of its ascent and then glide back to earth, Darpa said that its monitoring stations lost contact with the aircraft around half an hour into the flight and within nine minutes, the craft stopped sending signals and is now believed to have plunged into the ocean.

A previous launch attempt was abandoned and plane designs changed in April due to a fault on board the aircraft when an on-board computer detected an anomaly and ordered the plane to ditch in the ocean for safety reasons.

A second attempt on Wednesday was delayed to Thursday because of poor weather conditions, but technical difficulties were once again in the way.

The plane is part of plans from the United States Department of Defence to build what it calls a "prompt global strike" capability, enabling it to hit global targets within an hour with conventional or nuclear warheads.

California