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 1912. In early 1912, Igor Sikorsky became Chief Engineer of the aircraft division for the Russian Baltic Railroad Car Works ("Russko-Baltiisky Vagonny Zavod" or "R-BVZ") in Saint Petersburg. His work at R-BVZ included the construction of the first four-engine aircraft, the S-21 "Russky Vityaz", which he initially called "Le Grand" when fitted with just two engines, then as the "Bolshoi Baltisky" (The Great Baltic) when fitted with four engines for the first time, each wing panel's pair of powerplants in a "push-pull" tandem configuration previous to the four tractor-engined "Russki Vityaz". He also served as the test pilot for its