The Sikorsky S-72 Rotor Systems Research Aircraft (RSRA) was funded by NASA and the US Army to test advanced helicopter rotors in flight and featured detachable wings. Two S-72s were built and first flown in Stratford, CT on Oct 12, 1976. The first aircraft was delivered in July 1977 to NASA Wallops Island Flight Test Facility, VA and made its first full compound flighton April 10, 1978. The second S-72 was delivered to the NASA Ames Research Center in Fall 1978 and late joined by aircraft No. 1 in Sep 1979. Later used for RSRA/X-wing program 1986-1987. Msn 72-002 was NASA 546, 741 and N741NA.

The S-72 was an experimental high speed compound helicopter developed by Sikorsky for the US Army and NASA. Two were built and the program ran through the mid 1980s. This S-72, at last report, is located at the Moffett Field Museum.