It lasted a mere five minutes, but the X-51A Waverider Scramjet last test flight on May 1st reached speeds of Mach 5.1 before crashing into the Pacific Ocean. Scramjets are seen by many aviation engineers as a less expensive alternative to rockets for launching payloads from Earth to the edge of space. They are air breathing propulsion systems that compress air traveling at supersonic speed without any deceleration, mix in fuel and produce a combustive force so strong that it pushes the aircraft to hypersonic speeds.
The U.S. Air Force had built four X-51As to test the viability of scramjet technology. The previous tests including the last in August 2012 had largely been disappointing. But this time the craft performed as expected traveling over 425 kilometers in 6 minutes pulling off the longest flight by a scramjet to date. With only four minutes of fuel on board the end result, a crash into the Pacific, was totally expected. The Air Force was able to harvest 370 seconds of flight data.
The X-51A uses a hydrocarbon-based fuel making it more compatible with other aviation technology managed by the Air Force. The aircraft was built by Boeing, the engines designed by Pratt & Whitney.
With the completion of this last flight the X-51A program comes to an end but it wasn’t the only hypersonic technology game in town. Defense Advanced Research Project Agency (DARPA) has tested two prototype hypersonic bombers with one achieving Mach 20 in an August 2011 test flight that lasted nine minutes. But the DARPA craft was a glider and not an air-breathing scramjet.
Scramjets may prove to be a useful mode of transport for future sub-orbital flights cutting down the time it would take to fly from Sydney, Australia to Toronto, Canada from almost 20 hours to a mere 3.