The decision to abandon the "Tomahawk" in favor of more "Hueys" did not mark the end of the Army's involvement with the "Seasprite", for in mid-1964 a single UH-2A was selected for use in a joint Army-Navy helicopter research programme intended to explore the mechanics and techniques of high-speed rotor- borne flight. Under an Army Transportation Research Command contract the Seasprite was fitted with a General Electric YJ85 turbojet engine in addition to its existing T58 turboshaft and, so equipped, reached level-flight speeds in excess of 345kph. In early 1965 the craft was fitted with wings, and in subsequent test flights increased its top speed to more than 360kph. The extensive tests conducted with the 'Compound Seasprite' were of enormous value in determining the capabilities and limitations of high-speed compound rotorcraft. Upon completion of the test programme in early 1966 the aircraft was returned to its original configuration and sent back to the fleet.
S.Harding "U.S.Army Aircraft since 1947", 1990
Technical data for YUH-2
Crew: 3, engine: 1 x General Electric T58-GE-8 turboshaft, rated at 930kW + 1 x General Electric YJ-85 turbojet, rated at 1128kg, main rotor diameter: 13.41m, fuselage length: 11.15m, height: 4.11m, take-off weight: 5050kg, empty weight: 3247kg, max speed: 360km/h, cruising speed: 305km/h, service ceiling: 6065m, range: 725km