Sikorsky R-4 Sikorsky R-4 The Sikorsky R-4 is a two-seat helicopter designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass-produced helicopter and the first helicopter used by the United States Army Air Forces, the United States Navy, the United States Coast Guard and the United Kingdom's Royal Air Force and Royal Navy. In U.S. Navy and U.S. Coast Guard service, the helicopter was known as the Sikorsky HNS-1. In British service, it was known as the Hoverfly. The VS-316 was developed from the famous experimental VS-300 helicopter,
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