Sikorsky S-72 Sikorsky S-72 The Sikorsky S-72 was an experimental hybrid helicopter/fixed-wing aircraft developed by helicopter manufacturer Sikorsky Aircraft. The Rotor Systems Research Aircraft (RSRA) was developed by Sikorsky for NASA and the Army. The RSRA was developed to allow the inflight measurement of helicopter rotor characteristics. The airframe was developed using an existing Sikorsky S-61 main rotor, an S-61 roller gearbox, and a highly modified Sikorsky S-67 airframe. The RSRA could be fitted with TF34 turbofans and wings to allow compound helicopter configurations to be experimentally investigated at speeds up to . In addition, it could fly as a fixed-wing aircraft
Igor Sikorsky first flight on May 13, 1913. In recognition for his accomplishment, he was awarded an honorary degree in engineering from Saint Petersburg Polytechnical Institute in 1914. Sikorsky took the experience from building the Russky Vityaz to develop the S-22 "Ilya Muromets" airliner. Due to outbreak of World War I, he redesigned it as the world's first four-engined bomber, for which he was decorated with the Order of St. Vladimir. After World War I, Igor Sikorsky briefly became an engineer for the French forces in Russia, during the Russian Civil War. Seeing little opportunity for himself as an aircraft designer in