Just after World War II, Ryan engineers wondered whether the Ryan/U.S. Navy FR-1 Fireball, which had a thrust-to-weight ratio of 1 at low fuel quantities, would take off vertically. The United States Navy's Bureau of Aeronautics in 1947 awarded Ryan a contract, originally under the designation F3R,The Aeroplane, Volume 87, 1954. to investigate the development of a vertically launched jet fighter. This was part of a program to evaluate the feasibility of submarine-based aircraft. Ryan conducted remote controlled VTOL tethered rig tests from 1947 to 1950 and a flying rig in 1951. Ryan was awarded an Air Force contract in 1953 to develop an actual flying jet-powered VTOL aircraft, which was given the designation X-13. The aircraft was designed using calculations on a REAC 100, and two prototypes were ultimately built.
