US hypersonic aircraft sustains Mach 5.1 flight

An aircraft resembling a shark-nosed missile detached from a flying B-52 bomber and shot above the Pacific Ocean at more than 4,800 km/h in a historic test flight by the US Air Force.

The unmanned X-51A WaveRider sped westward for four minutes, reaching Mach 5.1, or more than five times the speed of sound, before making a planned plunge into the ocean.

It flew for longer than any other aircraft of its kind and travelled more than 425 kilometres, reigniting decades-long efforts to develop a vehicle that could travel faster than a speeding bullet.

A passenger aircraft travelling at such a speed could fly from Los Angeles to New York in less than an hour.

The United States Air Force has been flirting with hypersonic technology for more than half a century with little success. Aerospace engineers say that harnessing technology capable of sustaining hypersonic speeds is crucial to the next generation of missiles, military aircraft, spacecraft and passenger planes.

The X-51A, built and tested in southern California, was powered by an air-breathing engine that has no moving parts.