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,
Sikorsky S-19 performance and the aircraft was scrapped after a minor crash. Gotha WD.3 Sikorsky S-19 The Sikorsky S-19 was a Russian twin engine experimental prototype aircraft built late in 1916 by the Russian Baltic Railroad Car Works while Igor Sikorsky was chief engineer of the aircraft manufacturing division. The S-19 was a two bay sesquiplane powered by two Sunbeam Crusader water-cooled V-8 engines installed in push-pull configuration. Arranged as a twin-boom aircraft, it had a large rudder located in the center of the empenage. Two crewmembers occupied cockpits in the foreword most section of the booms in front of the lower