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
Sikorsky XP2S Sikorsky XP2S The Sikorsky XP2S was an American biplane patrol flying boat developed for the United States Navy during the early 1930s. After selling a small quantity of PS / RS patrol / transport amphibians to the Navy, Sikorsky (then a division of United Aircraft Corporation) endeavoured to interest the service in a patrol flying boat. Having received a development contract in mid-1930, Sikorsky delivered a complete aircraft for testing in June 1932. The XP2S-1, as the prototype was designated, was a two-bay, equal-span biplane of mixed construction. Its two R-1340 Wasp radial engines were mounted in a single nacelle