The United States Air Force has a serious need for speed. On May first their X-51A Waverider zoomed to an amazing Mach 5.1 – more than five times the speed of sound. While there was no pilot behind the stick of the hypersonic jet, the knowledge gained in developing and flying the X-51A paves the way for the hypersonics of the future.The X-51A was lifted from Edwards Air Force Base in California by a B-52H Stratofortress and was released at about 50,000 feet (15,000 meters). A solid rocket booster then kicked in to bring the X-51A to Mach 4.8 in 26 seconds. The solid rocket booster then separated and the X-51A’s air-breathing supersonic combustion ramjet – or scramjet – engine pushed it up the rest of the way to Mach 5.1 and up to an altitude of 60,000 feet (18,300 meters). Four minutes later its fuel supply had been used up and it nosed down, finally crashing (as planned) into the Pacific Ocean. In just over six minutes it had traveled over 230 nautical miles, making it the longest air-breathing hypersonic flight ever.