High above the ocean off the southern California coast, the Air Force’s unmanned X-51A Waverider broke the speed record! After it’s release from a B-52 Stratofortress, the X-51A blew past Mach 6 for 200 seconds! The previous record for a hypersonic scramjet flight was a mere 12 seconds.

The flight happened Wednesday morning, with the X-51A being set loose at an altitude of 50,000 feet. After 200 seconds, the vehicle developed an anomaly and it’s flight was terminated. Air Force parlance for the blew it up with an onboard self-destruct device. But fear not, they had built four to test. The flight began first with the X-51A using a solid-fuel rocket motor, taking the vehicle to a speed of Mach 4.8. As it burnt out and separated, the scramjet took over.

Scramjet technology is relatively new, though was first proposed some 40 years ago. The idea is for an ‘air-breathing’ engine capable of hypersonic speeds, Mach 5 and beyond. Many believe that such engines could be used for both sub-orbital and ‘single-stage-to-orbit’ space-planes. Hydrogen was considered to be the best fuel, however, the X-51A proved this week that hydro-carbon based fuels can be used instead. The vehicle’s engine was initially ignited with ethylene and then switched to using JP-7, the same fuel used by the SR-71 Blackbird.

In 2004, the Air Force test flew the X-43, which was a hydrogen-fueled scramjet UAV. They only carried two pounds of hydrogen, which lasted for just 10 seconds. The two successful of three X-43 test flights achieved speeds of Mach 7+ and Mach 9.8. These vehicles were similarly launched by a B-52 using a Pegasus rocket motor, originally designed for an anti-satellite missile system. The main purpose was to obtain valuable data on hypersonic flight conditions and to test new materials capable of withstanding the great speeds and temperatures.

The Air Force confirms that the X-51A Waverider is an experimental cruise missile. Part of their ongoing ‘Prompt Global Strike’ program. Last month, another test vehicle, the X-37 was launched. Very little is known about it’s mission, other than it is a reusable space-plane capable of long-term orbital operations. Many amateur astronomers have recorded sightings of it recently as it is still in orbit after it’s initial launch on April 22nd using an Atlas V booster. Originally, it had been scheduled to be carried into space inside the Columbia space shuttle. After Columbia’s tragic loss, the X-37 was redesigned for conventional rocket boosters, such as the Atlas and Delta types.