The Sikorsky R-4 was a two-place 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 to enter service with the United States Army Air Forces Navy and Coast Guard as well as for the United Kingdom's Royal Air Force and Royal Navy.
Made by Sikorsky Aircraft.
It is the successor of the Vought-Sikorsky VS-300 .