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CH-37 Mojave

H-37 Mojave of the US Army in flight.
Role	Cargo helicopter Type of aircraft
National origin	United States
Manufacturer	Sikorsky Aircraft
First flight	18 December 1953
Introduction	July 1956
Retired	Late 1960s
Primary users	United States Army United States Marine Corps
Number built	154
Developed into	Sikorsky S-60 Westland Westminster

The Sikorsky CH-37 Mojave (company designation S-56) is an American large heavy-lift helicopter of the 1950s.

Design and development

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 and production deliveries of the HR2S-1 began in July 1956 to Marine Helicopter Squadron One (HMX-1), with a total of sixty aircraft being produced.

The United States Army evaluated the prototype in 1954 and ordered 94 examples as the CH-37A, the first being delivered in summer 1956. All Marine Corps and Army examples were delivered by mid-1960. Army examples were all upgraded to CH-37B status in the early 1960s, being given Lear auto-stabilization equipment and the ability to load and unload while hovering. In the 1962 unification of United States military aircraft designations, the USMC examples were redesignated from HR2S-1 to CH-37C.

At the time of delivery, the CH-37 was the largest helicopter in the Western world and it was Sikorsky's first twin-engine helicopter. Two Pratt & Whitney R-2800 Double Wasp radial engines were mounted in outboard pods that also contained the retractable landing gear. This left the fuselage free for cargo, which could be loaded and unloaded through large clamshell doors in the nose. The early models could carry a payload of either three M422 Mighty Mites (a lightweight jeep-like vehicle) or 26 troops. For storage, the main rotor blades folded back on the fuselage and the tail rotor mast folded forward on the fuselage.^[1]

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 subsequently employed in later military helicopters. This accounted for the type's fairly short service life, all being withdrawn from service by the late 1960s, replaced in Army service by the distantly related CH-54 Tarhe and in the Marine Corps by the CH-53 Sea Stallion.

Four CH-37Bs 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.^[2] 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 recover film capsules descending from space by parachute.^[3]

Variants

XHR2S-1: Prototype Assault Transport for the US Marine Corps, powered by two 1,900 hp (1,400 kW) R-2800-54 engines, four built.
HR2S-1: Production model for USMC with modified engine nacelles, twin mainwheels and dorsal fin, redesignated CH-37C in 1962, 55 built (order for additional 36 cancelled).
HR2S-1W: Airborne early warning aircraft for the US Navy, two built.
YH-37: One HR2S-1 helicopter evaluated by the US Army.
H-37A Mojave: Military transport version of the HR2S for the US Army, changes included dorsal fin and modified rotor head fairing, redesignated CH-37A in 1962, 94 built.
H-37B Mojave: All but four of the H-37As were modified with a redesigned cargo door, automatic stabilization equipment and crashproof fuel cells. Later redesignated CH-37B.
CH-37A: H-37A redesignated in 1962.
CH-37B: H-37B redesignated in 1962.
CH-37C: HR2S-1 redesignated in 1962.
S-56: Sikorsky company designation for H-37.

Derivatives and related projects

Sikorsky S-60: a prototype "sky-crane" with a skeletal fuselage with a crew cockpit at the front.
Westland Westminster: Unable to get government support for licence production of the civil S-56, Westland Aircraft used the S-56 control systems, rotors and gearbox as the basis for the Westminster but used their own tubular frame and twin 2,900 hp (2,200 kW) Napier Eland turboshafts for power in a flying test rig. 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

Surviving aircraft

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CH-37B (Army Ser. No. 55-644) is on display at the United States Army Aviation Museum at Fort Rucker, 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. 57-1651) is on display at the U.S. Army Transportation Museum at Fort Eustis, Virginia.
CH-37B (Army Ser. No. 58-0999) is on display at the Evergreen Aviation & Space Museum in McMinnville, Oregon.
CH-37C (BuNo 145864) is on display at the National Museum of Naval Aviation at Naval Air Station Pensacola, Florida.
CH-37B (Army Ser. No. 57-1646) is on display at the Classic Rotors Museum at the Ramona Airport, Ramona, CA.

Specifications (CH-37 Mojave)

Data from U.S. Army Aircraft Since 1947 ^[6]

General characteristics

Crew: three
Capacity: 26 troops or 24 stretchers
Length: 64 ft 3 in (19.58 m) fuselage
Height: 22 ft 0 in (6.71 m)
Empty weight: 20,831 lb (9,449 kg)
Max takeoff weight: 31,000 lb (14,061 kg)
Powerplant: 2 × Pratt & Whitney R-2800-54 Double Wasp 18-cylinder air-cooled radial piston engines, 2,100 hp (1,600 kW) each
Main rotor diameter: 72 ft 0 in (21.95 m)
Main rotor area: 4,072 sq ft (378.3 m²) blade section NACA 0012^[7]

Performance

Maximum speed: 113 kn (130 mph, 209 km/h)
Cruise speed: 100 kn (120 mph, 190 km/h)
Range: 126 nmi (145 mi, 233 km) with maximum payload
Service ceiling: 8,700 ft (2,700 m)
Rate of climb: 910 ft/min (4.6 m/s) ^[8]

References

External links

Sikorsky aircraft

Sikorsky aircraft
Fixed-wing aircraft (company designations)	S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-11 S-12 S-13 S-14 S-15 S-16 S-17 S-18 S-19 S-20 S-21 S-22 S-23 S-24 S-25 S-26 S-27 S-28 S-29-A S-30 S-31 S-32 S-33 S-34 S-35 S-36 S-37 S-38 S-39 S-40 S-41 S-42 S-43 VS-44 S-45
Fixed-wing aircraft (military designations)	C-6 C-28 JRS JR2S PS P2S RS XBLR-3 XPBS XSS XV-2
Helicopters (company designations)	VS-300 (S-46) S-47 S-48 S-49 S-50 S-51 S-52 S-53 S-54 S-55 S-56 S-57 S-58 S-59 S-60 S-61 S-61L/N S-61R S-62 S-63 S-64 S-65 S-66 S-67 S-68 S-69 S-70 S-71 S-72 S-73 S-74 S-75 S-76 S-80 S-92 S-95 S-97 S-100 S-102 S-103 S-300 S-333 S-434
Helicopters (military designations)	SH-3 Sea King HH-3E/F R-4 H-5 H-6 H-18 H-19 Chickasaw H-34 Chocataw CH-37 Mojave XH-39 HH-52A Seaguard CH-53 Sea Stallion CH-53E Super Stallion CH-53K King Stallion MH-53 CH-54 Tarhe UH-60 Black Hawk HH-60G Pave Hawk HH-60J/MH-60T MH-60R/S Seahawk SH-60B/F Seahawk H-60J/K VH-60 RAH-66 Comanche VH-92 Patriot CH-124 Sea King CH-148 Cyclone HLH
Experimental aircraft	Cypher/Cypher II Firefly Raider Raider X SB-1 X2 XBLR-3 XV-2

United States helicopter designations, Army/Air Force and Tri-Service systems

Numerical sequence used by USAAC/USAAF/USAF 1941–present; U.S. Army 1948–1956 and 1962–present; U.S. Navy 1962–present

Army/Air Force sequence
(1941–1962)

Prefix R-, 1941–1948	R-1 R-2 R-3 R-4 R-5 R-6 R-7 R-8 R-9 R-10 R-11 R-12 R-13 R-14 R-15 R-16
Prefix H-, 1948–1962	H-5 H-6 H-9 H-10 H-11 H-12 H-13 J H-15 H-16 H-17 H-18 H-19 H-20 H-21 H-22 H-23 H-24 H-25 H-26 H-27 H-28 H-29 H-30 H-31 H-32 H-33 H-34 H-35 H-36¹ H-37 H-38¹ H-39 H-40 H-41 H-42 H-43 H-44¹ H-45¹

Tri-service sequence
(1962–present)

1962 redesignations	H-13 F J H-19 H-21 H-23 H-25 H-34 H-37 H-43
New designations	H-46 H-47 H-48 H-49 H-50 H-51 H-52 H-53 CH-53/E/K HH-53/MH-53 H-54 H-55 H-56 H-57 H-58 H-59 H-60 UH-60 SH-60 HH-60 MH-60 H-61 H-62 H-63 H-64 H-65 H-66 H-67 H-68 H-69¹ H-70 H-71 H-72 H-73
Alternate sequence	H-1 AH-1/J/T/W/Z UH-1/N/Y H-2 G H-3 CH-3/HH-3 SH-3 H-4 H-5 H-6 AH-6 MH-6 OH-6
Non-sequential	H-90 H-92 CH-92/VH-92 H-139

¹ Not assigned

USN helicopter designations pre-1962

Helicopter, Anti-submarine

Bell	HSL
Sikorsky	HSS-1 HSS-2

Helicopter, Crane

McDonnell	HCH

Helicopter, Observation

Convertawings	HOC
Hiller	HOE
Gyrodyne	HOG
Kaman	HOK
Sikorsky	HOS HO2S HO3S HO4S HO5S

Helicopter, Trainer pre-1948

Sikorsky	HNS

Helicopter, Trainer 1948-1962

Hiller	HTE
Kaman	HTK
Bell	HTL

Helicopter, Transport 1944-1962

Boeing Vertol	HRB
McDonnell	HRH
Piasecki	HRP
Sikorsky	HRS HR2S HR3S

Helicopter, Utility pre-1949

McDonnell	HJD
McDonnell	HJH
Piasecki	HJP
Sikorsky	HJS

Helicopter, Utility 1950-1962

Kaman	HUK HU2K
Bell	HUL
McCulloch	HUM
Piasecki	HUP
Sikorsky	HUS HU2S

Authority control: National