High Quality Content by WIKIPEDIA articles! 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.