The U.S. military launched an experimental hypersonic aircraft on its swan song test flight Wednesday (May 1), accelerating the craft to more than five times the speed of sound in the longest-ever mission for a vehicle of its kind.
A Boeing X-51A WaveRider unmanned hypersonic vehicle achieved the longest air-breathing, scramjet-powered hypersonic flight in history, flying for three and a half minutes on scramjet power at a top speed of Mach 5.1. The vehicle flew for a total time of more than six minutes.
A U.S. Air Force B-52H Stratofortress from Edwards Air Force Base released the X-51A from 50,000 feet above the Point Mugu Naval Air Warfare Center Sea Range at 10:55 a.m. Pacific time. After the B-52 released the X-51A, a solid rocket booster accelerated the vehicle to about Mach 4.8 before the booster and a connecting interstage were jettisoned. The vehicle reached Mach 5.1 powered by its supersonic combustion scramjet engine, which burned all its JP-7 jet fuel. The X-51A made a controlled dive into the Pacific Ocean at the conclusion of its mission. The test fulfilled all mission objectives.
The flight was the fourth X-51A test flight completed for the U.S. Air Force Research Laboratory. It exceeded the previous record set by the program in 2010.
The U.S. military has been studying hypersonic flight in order to develop new weapons capable of striking targets anywhere on Earth within an hour. In addition to the Air Force’s work with the X-51A, the Defense Advanced Research Projects Agency (DARPA) has launched two test flights of its HTV hypersonic bomber prototype, which reached Mach 20 in an August 2011 test flight before losing control.
While that 2011 HTV mission lasted nine minutes, the vehicle only demonstrated controlled flight for three minutes during the test. The HTV was also a glider vehicle, and not an air-breathing scramjet.