An aircraft designed by Boeing has made history by achieving the longest ever hypersonic flight by a jet-fuel powered aircraft.

The X-51A WaveRider flew for three-and-a-half minutes at five times the speed of sound, the US Air Force has confirmed.

The last of four unmanned experimental military aircraft built by Boeing flew at a top speed of Mach 5.1 over the Pacific Ocean on May 1, the Air Force said.

The total flight covered 230 nautical miles in just over six minutes before the hypersonic cruiser plunged into the ocean.

The Air Force says it was the longest of the four X-51A test flights and the longest air-breathing hypersonic flight ever.

The technology demonstration opens the door to future practical use of hypersonic jet-fuelled aircraft.

Previous aircraft developed by NASA used hydrogen as a fuel, but it would take a giant tank to fly for longer periods.

A video released by Boeing and the US Air Force showed the WaveRider dropping down from under the left wing of a B-52 bomber at an altitude of about 50,000 feet and then accelerating away, leaving behind a long vapour trail.

It accelerated to Mach 4.8 in about 26 seconds, powered by a solid rocket booster built by Pratt & Whitney Rocketdyne.

After separating from the booster, the cruiser’s scramjet engine lit and accelerated it to Mach 5.1 at 60,000 feet.

The vehicle continued to send back data to the control station at Edwards Air Force Base in California until it made a controlled dive into the Pacific Ocean.

The Air Force said the four X-51As were built to demonstrate the new technology, not as a prototype for a new weapon system.

The programme is aimed at paving the way to future hypersonic weapons, hypersonic intelligence, surveillance and reconnaissance, and future access to space, it said.

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