Edwards AFB, Calif -- The X-51A Waverider Scramjet Engine Demonstrator vehicle completed the longest ever, supersonic, combustion, ramjet-powered, hypersonic flight, during a mission performed off the coast of southern California. The more than 200-second burn by the Waverider's Pratt & Whitney Rocketdyne-built air breathing scramjet engine, accelerated the test vehicle to Mach 5.
The longest scramjet burn during a flight test lasted a mere 12 seconds (in a NASA X-43A). Air Force officials called the test an unqualified success, and considered the mission the first use of a practical hydrocarbon-fueled scramjet in flight. The X-51 departed Edwards AFB, at about 10 o'clock A.M,, carried aloft under the left wing of an Air Force Flight Test Center B-52H Stratofortress. The engine vehicle flew at 50,000 feet over the Point Mugu Naval Air Warfare Center Sea Range. Four seconds after the Waverider released from the B-52, an Army Tactical Missile solid rocket booster accelerated the X-51 to approximately Mach 4.8 before it and a connecting inter-stage jettisoned. At that point, the X-51’s SJY61 engine ignited. The successful flight reached an altitude of nearly 70,000 feet and a top speed of Mach 5.
The speed of sound consists of traveling a mile in 4.7 seconds or less. Mach speed is calculated by taking the speed of an object and dividing that by the speed of sound. Mach 1.0 or less is considered Subsonic; Transonic is defined as reaching Mach 1.0; faster than Mach 1.0 is Supersonic and faster than Mach 5.0 defines Hypersonic.