Sikorsky R-4 end of the boom near the tail rotor while others had it positioned at the midpoint of the boom. Additionally, some had short "stub" exhaust pipes from the engine while others had a much longer one which extended vertically and then aft above the main landing gear struts. 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
Igor Sikorsky war-torn Europe, and particularly Russia, ravaged by the October Revolution and Civil War, he immigrated to the United States, arriving in New York on March 30, 1919. In the U.S., Sikorsky first worked as a school teacher and a lecturer, while looking for an opportunity to work in the aviation industry. In 1932, he joined the faculty of the University of Rhode Island to form an aeronautical engineering program and remained with the university until 1948. He also lectured at the University of Bridgeport. In 1923, Sikorsky formed the Sikorsky Manufacturing Company in Roosevelt, New York. He was helped by