In 1954 McDonnell Aircraft began development of test missiles based on the concept of aeroballistic or 'lifting body' flight.

Three McDonnell Hypersonic Missiles were launched from Cape Canaveral, Florida in 1959. Level flight was achieved at Mach 5 within the Earth's atmosphere. McDonnell's design proved to be a breakthrough in the development of aerospace vehicles capable of atmospheric maneuvering at hypersonic speeds.