Description:

The X-19 was a development of the Curtiss-Wright X-100, which had first demonstrated the radial force lift concept. The aircraft was intended to be a further development of this aircraft, and to be designated the X-200, but the U.S. Air Force contracted for conversion of two prototypes (designated X-19) as part of the Army/Navy/Air Force Tri-Service Assault Transport Program,

Source: AHS VSTOL Wheel, Curtiss-Wright X-19