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 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 military, he tried to build another successful aircraft for them. The S-10 was a modified S-6B built by the Russo-Baltic Carriage Factory. Approximately sixteen production versions of the S-10 were built. It had a less powerful engine and generally weaker structure than the S-6. They had either an 80 HP Gnome Monosoupape or a 100 HP Argus Motoren engine. Some were deployed on the