The Sikorsky CH-37 Mojave (company designation S-56) was a large heavy-lift helicopter by the standards of the 1950s. The S-56 came into being as an assault transport for the United States Marine Corps (USMC), with a capacity of 26 fully-equipped troops; the order was placed in 1951, the first prototype flew in 1953, and production deliveries of the HR2S began in July 1956 to the Marine Corps' HMX-1, sixty aircraft in total being produced. WIKI LINK Marines debarking from a Sikorsky HR2S-1 helicopter. In 1962 it was redesignated CH-37C. 1956. A combination of two pictures of the Sikorsky HR2S-1W with AN/APS-20E radar. Two aircraft (BuNos 141646/141647) were built. 1957. CH-37B in flight.