US aircraft hits mach 5.1

An unmanned US military aircraft has flown more than five times the speed of sound in a record breaking test flight, the US Air Force said on Friday.

The aircraft, called the X-51A Waverider, reached a speed of Mach 5.1 over the Pacific Ocean on Wednesday, traveling more than 230 nautical miles, or 426 kilometers, in just over six minutes according to the US Air Force website.

The aricraft was carried into the air by a B52 bomber and released at an elevation of around 50,000 feet, or 15,240 meters, after which a rocket booster accelerated the aircraft to a speed of Mach 4.8 in 26 seconds.At this point a supersonic ramjet pushed the aircraft up to Mach 5.1 at 60,000 feet (18,288 meters) before it plunged into the ocean.
Any speed above Mach 5 is generally referred to as hypersonic.

The test was the last and the longest of four experimental flights that were planned for the aircraft, which the US Air Force has said is a key achievement in advancing technology to deliver high-speed weapons strikes around the world.