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-18 leave the ground. Sikorsky S-18 The Sikorsky S-18 was a Russian twin engine aircraft designed by Igor Sikorsky and built by the Russian Baltic Railroad Car Works aviation division at Petrograd during World War I. The S-18 was a large three bay biplane fighter/interceptor powered by two Sunbeam Crusader V-8 water-cooled engines mounted on the lower wing in a pusher configuration. The aircraft featured armor protection for both crew members with the gunner/observer seated in the nose and armed with a single machine gun. The aircraft was very heavy and with the less than reliable Sunbeam engines neither example built