Mach 6 aircraft lost seconds after takeoff

The Air Force has suffered another setback to its attempts to build a plane that could reach anywhere in the world within an hour.

X-51A WaveRider hits Mach 5

The sleek X-51A WaveRider managed to achieve a top speed of Mach 5 at an altitude of 70,000 feet during a recent test flight by the US Air Force.