The world's fastest plane, which travels at 22 times the speed of a commercial jet, was launched by the US military on Thursday - before it subsequently crashed into the ocean.

The unmanned Falcon HTV-2 travels at more than 13,000 MPH, and is capable of reaching Sydney from London in less than one hour.

The plane was attached to a rocket and before lifting off from Vandenberg Air Force Base in California.

After detaching from the rocket at the edge of space, the plane was guided by engineers on a flight during which it travelled at around 20 times the speed of sound and withstand temperatures of 2,000C.

Unfortunately the plane later crashed unexpectedly after 36 minutes.

Before the flight researchers conducting the test had admitted that they were not quite sure how the plane will handle.

Air Force Major Chris Schulz said: "It's time to conduct another flight test to validate our assumptions and gain further insight into extremely high Mach regimes that we cannot fully replicate on the ground."

"Only flight testing reveals the harsh and uncertain reality."

A previous test flight in April after the plane, which flew for just over two minutes at 16,700 MPH, failed and intentionally crashed into the ocean for safety reasons.

The US Defence Agency's Twitter page will be providing live updates of the launch throughout the day.