Sikorsky R-5

The Sikorsky R-5, later redesignated H-5 and known inside the company as the S-48, with the civil S-51 and the British licence-built Westland Dragonfly, was a two-seat piston helicopter that Sikorsky designed as a larger and more capable successor to the R-4. It had a longer fuselage, a bigger rotor and a 450-horsepower Pratt and Whitney Wasp Junior radial engine, and the first prototype flew on 18 August 1943. The United States Army Air Forces, the Air Force, the Navy and the Coast Guard flew it, and the civil S-51 became the first helicopter operated commercially, starting in 1946. Production ended in 1951 after more than 300 had been built.