on the Gorgon IV. The ramjet Gorgon IVs, made by Glenn Martin, were tested in 1948 and 1949 at Naval Air Station Point Mugu. The ramjet was designed at the University of Southern California and manufactured by the Marquardt Aircraft Company. The engine was 7 ft long and 20 in in diameter and was positioned below the missile.

In the early 1950s the US developed a Mach 4+ ramjet under the Lockheed X-7