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 VS-44 Sikorsky VS-44 The Sikorsky VS-44 was a large four-engined flying boat built in the United States in the early 1940s by Sikorsky Aircraft. The VS-44 was designed primarily for the transatlantic passenger market, with a capacity of 40+ passengers. Three units were produced: "Excalibur", "Excambian", and "Exeter". In the early 1930s, the primary mode of long-distance air travel over oceans was in flying boats, due to the ease of constructing docking facilities on shore without having to construct runways, and the possibility of malfunction forcing a sea landing. One flying boat designer was Russian immigrant Igor Sikorsky who had founded