From Wikipedia
The Sikorsky CH-37 Mojave (company designation S-56) is an American large heavy-lift military helicopter of the 1950s. It entered service as the HR2S-1 Deuce with the USMC in 1956, and as the H-37A Mojave with the U.S. Army that same year. In the early 1960s, the designation was standardized to CH-37 for both services, with the HR2S-1 redesignated as CH-37C specifically.
Developed in the early 1950s, with its first flight in 1953, it filled a 1950 Navy requirement for an assault helicopter that could carry up to 20 Marines and haul combat equipment. The design includes a front-loading ramp with side opening clamshell doors on the nose. It was powered by two radial piston engines. It served in active military service well into the 1960s, including in Indochina, before being replaced.
