High Quality Content by WIKIPEDIA articles! The Lockheed X-7 (dubbed the "Flying Stove Pipe") was an unmanned test bed for ramjet engines and missile guidance technology. It was carried aloft by a B-29 or B-50 Superfortress carrier aircraft. The booster rocket ignited after launch and propelled the vehicle to a speed of 1,000 mph (1,625 km/h). The booster was then jettisoned, and the underslung ramjet took over from that point. The X-7 eventually returned to Earth, its descent slowed by parachute. A maximum speed of 2,881 mph (4640 km/h / Mach 4.31) was attained, setting a record for fastest air-breathing aircraft at the time. A total of 130 X-7 flights were conducted from April 1951 to July 1960.