An unmanned U.S. military jet designed to fly at hypersonic speeds and travel from London to New York in just 45 minutes has failed during a trial as it crashed into the Pacific Ocean within seconds of its launch.

The test had called for a five-minute flight off the coast of southern California at Mach 6- up to 7,300 kmph — six times the speed of sound.

The X-51A Waverider was dropped from a B-52 bomber on Wednesday and launched by a rocket booster as planned but the flight was over in seconds after a control fin malfunctioned, said the U.S. Air Force in a statement. The faulty control fin meant that the vehicle’s flight ended before a specially-designed “Scramjet” engine could be ignited, it said.

“It is unfortunate that a problem with this subsystem caused a termination before we could light the Scramjet engine,” said Charlie Brink, Programme Manager for the project. “All our data showed we had created the right conditions for engine ignition and we were very hopeful to meet our test objectives,” he said in a statement.

The Waverider separated from the B-52 over Point Mugu naval sea range.

However after 16 seconds, a fault was identified with one of the cruiser control fins.

One of four X-51A vehicles remains after a series of tests with mixed results.

The Pentagon — which helped fund the project — has been testing hypersonic technologies in an effort to develop faster missiles. It has also been suggested the research could eventually help build a commercial plane with the promise of London to New York trips taking as little as less than an hour, or Tokyo to Paris journeys slightly more than double that time. For now only one X-51A vehicle remains and the Air Force has not yet decided whether to organise a fourth test.

The air travel distance between London and New York is around 5570 km.

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