The Lockheed X-7 (dubbed the "Flying Stove Pipe") is an American unmanned test bed of the 1950s for ramjet engines and missile guidance technology.

It was the basis for the later Lockheed AQM-60 Kingfisher, a system used to test American air defenses against nuclear missile attack.

The X-7 was called into production by the United States Air Force requirement for the development of an unmanned ramjet test plane with a top speed of at least Mach 3 (3,200 km/h; 2,000 mph).

[1] Being the testbed for several yearlong projects, the X-7 underwent many structural changes to adapt more closely for its intended purpose.

[3] During the testing of the SAMs, the X-7 outperformed the missiles and a very small number of critical hits were achieved.

The use of steel was due to the inability of aluminum to endure air friction heating at hypersonic speeds, years before the widespread introduction of titanium.