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
Sikorsky S-5 during a country fair at Belaya Tzerkov, near Kiev. Between nine and ten flying hours were logged before the S-5 was lost in late fall. The crash was caused by fuel starvation due to debris (a mosquito) blocking the carburetor jet. Sikorsky S-5 The Sikorsky S-5 was an early Russian single seat biplane design by Igor Sikorsky, completed in late April 1911. The S-5 was powered by a Argus water-cooled engine turning a propeller Sikorsky designed and built himself. The fabric covering the wooden wings was tightened with pure alcohol and glue mixed with boiling water while the fuselage structure