The empty weight of the CH-37 was 20,800 pounds and the maximum takeoff weight was 31,000 pounds. This gave a useful load of just over 10,000 pounds. The useful load does not factor in fuel so that number is actually reduced further by how far/long the helicopter needs to fly…
Designed to fulfill a 1950 Marine Corps requirement for a series of large transport helicopters, for a decade the CH-37 Mojave held the distinction of being the largest helicopter flying outside the Soviet Union.
The CH-37 prototype first flew in 1953 and entered service in 1956 with the US Army and US Marine Corps.
‘Helicopters in the mid-1950s and prior were powered by piston engines because jet engines were still fairly new and really only applied to new fighter aircraft,’ says Tyler Monson, an aviation expert on Quora. ‘These piston engines were originally designed for WWII bombers and fighters and were large and heavy to provide as much power as possible. While other helicopters of the 1950s were powered by a single-piston engine placed in the nose, the CH-37 was designed with twin-piston engines mounted in pods beside the fuselage.
‘The transport and heavy lift mission of the CH-37 meant that lots of internal space was needed within the helicopter for personnel and any cargo that would not be slung beneath on a cable. The cockpit was raised at the front of the aircraft and the nose below it opened into the large cabin via clamshell doors and a loading ramp.
‘Now you can understand why the CH-37 looks the way it does. But simply being ugly does not make a bad helicopter, so what was the problem?
‘It was just too underpowered. Its two 18-cylinder Pratt & Whitney R-2800 Double Wasp engines put out 2100 horsepower each. That sounds like a lot because it is. These engines were very powerful but also very heavy. Each one weighed 2360 pounds alone which gave a power-to-weight ratio of 0.89.’
He continues;
‘The empty weight of the helicopter was 20,800 pounds and the maximum takeoff weight was 31,000 pounds. This gave a useful load of just over 10,000 pounds. The useful load does not factor in fuel so that number is actually reduced further by how far/long the helicopter needs to fly. Now you can see why the CH-37 proved underwhelming.
‘By 1959 the first turboshaft engine helicopters, such as the famous UH-1 Huey, entered production. These turboshafts were much smaller than their piston counterparts and with much better power-to-weight ratios. Now turbine helicopters (such as the HH-3, CH-46, CH-47, CH-54, and CH-53) were being produced that exceeded the CH-37 in nearly every stat. Speed, maximum takeoff weight and useful load, range, altitude, and size. These helicopters served alongside the relatively small numbers of CH-37s in Vietnam and in the late 1960s the CH-37 was retired completely.
‘The CH-53, for comparison to the CH-37 is as follows.
‘Entered service in 1966 with the US Navy and US Marine Corps. Powered by two General Electric turboshafts producing 3,925 horsepower each and a power-to-weight ratio of 5.5. An empty weight of 23,600 pounds and a maximum takeoff weight of 42,000 pounds gives a useful load of 18,400 pounds. The CH-53 could fly faster, higher, and further than the CH-37 and quickly took over in Marine’s heavy lift and transport duties.’
Monson concludes;
‘As for the few Mojaves left in Vietnam, they found a niche as a recovery helicopter, salvaging downed aircraft and equipment from the field.
‘After its retirement, it was either scrapped or found homes in museums and as static displays. It never found a career in the civilian world like the H-19 and H-34 did because it was just too large and too expensive. It might not be the absolute worst helicopter put into production but the timing of its introduction sure highlighted its deficiencies.’
Photo by U.S. Navy and U.S. Army