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 Ilya Muromets Air Shooting and Bomb-dropping School in Serpukhov. One Ilya Muromets S-22 replica exists in the Monino Air Force Museum near Moscow. Sikorsky Ilya Muromets The Sikorsky "Ilya Muromets" () (Sikorsky S-22, S-23, S-24, S-25, S-26 and S-27) were a class of Russian pre-World War I large four-engine commercial airliners and military heavy bombers used during World War I by the Russian Empire. The aircraft series was named after Ilya Muromets, a hero from Slavic mythology. The series was based on the Russky Vityaz or Le Grand, the world's first four-engined aircraft, designed by Igor Sikorsky. The Ilya Muromets aircraft as