https://en.wikipedia.org/wiki/Sikorsky_CH-37_Mojave

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 utilizing 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-engined 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.

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short service life, all being withdrawn from service by the late 1960s, replaced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 1963 to assist in the recovery of
downed U.S. aircraft. 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 spy satellite film capsules descending
from space by parachute.


Role
Cargo helicopter

National origin
United States

Manufacturer
Sikorsky Aircraft

First flight
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

Specifications (CH-37 Mojave)

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

Performance
Maximum speed: 113 kn (130 mph; 209 km/h)
Cruise speed: 100 kn (115 mph; 185 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)




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