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-34 Sikorsky S-34 The Sikorsky S-34 was a 1920s American six-seat sesquiplane, designed and built by the Sikorsky Manufacturing Corporation. Only one was built but the design led to the successful Sikorsky S-38. The S-34 was a sesquiplane amphibian with a boat hull, being powered by two tractor Wright Whirlwind J-4 engines. It had a boom-mounted twin-rudder tail unit and room inside the hull for five passengers. During a test flight in November 1927 one engine failed and the S-34 crashed and sank. Igor Sikorksy and the others onboard escaped without injury but the S-34 was destroyed. It was the first