After the end of World War II and during the Korean War, the helicopter demonstrated its versatility for hovering flight in support of ground troops and for rescue. However, the large diameter rotor required for hovering flight compromised forward flight speed, payload and range. Because of this, both the military services and the aircraft industries were conducting studies (costing over $200,000,000) of aircraft configurations that would provide an aircraft with both a hovering capability and a short takeoff and landing (V/STOL) capability. Flight controls should be similar to those in helicopters during hover and conventional aircraft in forward flight. Early in the 1950’s, the first generation of V/STOL aircraft emerged as tail sitters, wire hangers and hybrid helicopters. Technically they were considered a success since they flew with some degree of control and their performance as demonstrated for short periods at air shows was spectacular. However, V/STOL aircraft were clearly not developed sufficiently for operational use. Lockheed developed the XV-4A, Ryan developed the XV-5A lift-fan aircraft, Curtiss-Wright developed the X-19 and Bell developed the ducted-fan X-22. In Canada, the tilt-wing CL-84 was Canadair’s V/STOL demonstrator, while Germany’s Dornier Company developed the DO-31. The three major military services (Army, Navy and Air Force) considered that this flying hardware experience would support the development of a prototype V/STOL airplane that could augment helicopters in transport-type missions. If this prototype program was successful, an airplane based on the prototype experience could be developed. Professor Perkins of Princeton conducted a V/STOL study for the Department of Defense in 1959. This study helped create the XC-142A tilt-wing V/STOL program.
The three services jointly developed a Request for Proposal (RFP) for a V/STOL transport airplane that could be evaluated in an operational environment. The RFP was issued to all interested helicopter and aircraft manufacturers in January 1961, with manufacturers’ proposals due in April 1961. The U.S. Air Force was the procuring service.
Vought Helicopter Heritage
To view the film of the XC-142A Operational Stability Test of 1965 select link: