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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 clam shell 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.
Many ex-military models went onto civilian service in the 1970s. This was the biggest helicopter in the world to enter service at the time, and one of the earliest twin engine models. It was known for being noisy but earned a good reputation for reliability. The Navy adapted it to carry a naval radar, with two entering service as HR2S-1W.
The design led to a production attempt as the Westland Westminster in the United Kingdom; prototypes were produced, but it did not go into full production. The S-56 was also the basis for the S-60 Skycrane helicopter prototype.
Design and development
thumb|A HR2S-1
thumb|Loading a [[Dodge WC]]
thumb|A HR2S-1 with a M422 Mighty Mite
The S-56 came into being as an assault transport for the United States Marine Corps (USMC), with a capacity of 26 fully equipped Marines. An order for the aircraft was placed in 1951 using the U.S. Navy/U.S. Marine Corps designation of the time of HR2S. The first prototype, the XHR2S-1 flew in 1953. Production deliveries of the HR2S-1 "Deuce" began in July 1956 to Marine Helicopter Squadron One (HMX-1), with sixty aircraft being produced.
The HR2S-1 set three records in 1956: a speed record without payload of 162.7 mph (141.4 kts); an altitude record of 12,100 ft (3,688.1 meters) with a 11,023 lbs (5,000 kg) load; and a load carrying record of 13,227 lbs (6,000 kg) to 6,561 feet (2,000 meters).
The CH-37 was one of the last heavy helicopters to use piston engines, which were larger, heavier and less powerful than the turboshaft engines employed in later military helicopters. This accounted for the CH-37's fairly short service life, all being withdrawn from service by the late 1960s, replaced in Army service by the distantly related CH-54 Tarhe and in the Marine Corps by the CH-53 Sea Stallion.
Six CH-37C's were deployed to Vietnam in September 1965 to assist in the recovery of downed U.S. aircraft, serving in this role from Marble Mountain Air Facility until May 1967. They were very successful at this role, recovering over US$7.5 million worth of equipment, some of which was retrieved from behind enemy lines. The CH-37 was also used to perform mid-air recovery of rocket nose cones at the White Sands Missile Range.
154 were produced by the time production ended. Of those, 94 were H-37A, and 90 that were converted to H-37B, later CH-37A and B respectively. It remains the largest piston powered helicopter.
;HR2S-1
:Production model for the USMC with modified engine nacelles, twin mainwheels and dorsal fin. Redesignated CH-37C in 1962. 55 were built, with an order for an additional 36 cancelled.
;HR2S-1W
:Airborne early warning aircraft for the US Navy, two built.
;H-37
:The H-37 followed the HR2S-1 in 1954 as an army helicopter. 94 were built between 1954 and 1960. It is credited with a maximum speed of 126 mph. Due to vibration they changed to a six-bladed S-64 rotor. The private venture project was ended when Westland took over three British helicopter companies and their more advanced and funded projects.
Operators
;
- United States Army
- United States Marine Corps
- HMR(M)-461 1957–1966
- HMR(M)-462 1957–1965
- HMR(M)-463 1958–1959
Survivors
thumb|Closeup of the engine nacelle housing the Wasp radial engine at museum
- CH-37B (Army Ser. No. 55-0644) is on display at the United States Army Aviation Museum at Fort Novosel, Alabama.
- CH-37B (Army Ser. No. 58-1005) "Tired Dude" is on display at the Pima Air and Space Museum adjacent to Davis-Monthan Air Force Base in Tucson, Arizona.
- CH-37B (Army Ser. No. 58-0999) is on display at the Evergreen Aviation & Space Museum in McMinnville, Oregon.
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General characteristics
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|crew=three
|capacity=26 troops or 24 stretchers
|length ft=64
|length in=3
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|height ft=22
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|empty weight lb=20831
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|max takeoff weight lb=31000
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Powerplant
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|eng1 number=2
|eng1 name=Pratt & Whitney R-2800-54 Double Wasp
|eng1 type=18-cylinder air-cooled radial piston engines
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|eng1 hp=2100
|rot number=1
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|rot dia ft=72
|rot dia in=0
|rot area sqft=4072
|rot area note=blade section NACA 0012
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Performance
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|max speed kts=113
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|cruise speed kts=100
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|range nmi=126
|range note=with maximum payload
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|ceiling ft=8700
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|climb rate ftmin=910
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See also
- List of military aircraft of the United States
References
External links
- CH-37 Mojave US Army Aviation history fact sheet
- Information and Specs on the H-37
- Photos of CH-37's from 49th Avn Bn, CAL ARNG, and others
- HELIS.com Sikorsky S-56/H-37/HR2S Database