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-10 by another 3050 mm and the Gnome engine was replaced by a stronger Monosoupape engine, the S-10 served as both a reconnaissance and trainer on floats with the Baltic Fleet. Russian test pilot Gleb Alekhnovich set a Russian record by flying non-stop 500 km in 4 hours 56 minutes and 12 seconds with the S-10. Data from "History of aircraft construction in the USSR". Sikorsky S-10 The Sikorsky S-10 was a Russian Empiren military twin-float seaplane that served with the Baltic Fleet from the summer of 1913 to 1915. After Igor Sikorsky built the successful Sikorsky S-6 for the Russian