Top speed 169 km/h | Manufacturer Bell Helicopter | |
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The Bell R-12 (Model 48), redesignated as the Bell H-12, was an American 1940s military utility helicopter built by the Bell Helicopter company.
Contents
Design and development
During 1946, Bell Helicopter began development of a new utility helicopter, the Model 42, much larger than the Model 47, which utilized a scaled-up version of the Model 47's rotor system. Three prototypes were built but serious rotor problems and complexity of mechanical systems precluded production. The initial Model 42 variant was civilian, but the United States Air Force ordered the development of its military variant, the Model 48. Two prototypes were ordered as the XR-12, powered by a single 540 horsepower (403 kW) Pratt & Whitney R-1340-AN-1 radial engine and featuring seating for five. Of very similar construction to the Model 42, the Model 48 had a shorter rotor mast. A production batch of 34 helicopters was ordered, under the designation R-12A, but cancelled in 1947.
Another enlarged prototype (the XR-12B, Model 48A) with seats for eight plus two pilots and a more powerful 600 horsepower (447 kW) Pratt & Whitney R-1340-55 engine was also ordered, followed by ten pre-series YR-12B helicopters, with a glazed nose, instead of the car-like nose of the Model 42 and XR-12. While under flight test the helicopter was redesignated the H-12, but the results were not satisfactory, as there were major problems with the main rotor due to blade weaving and poor rotor governor performance.
Operational history
No production H-12 aircraft were built but the prototypes and preproduction aircraft were used for various test and development programs.
Variants
Operators
Specifications (XR-12B)
Data from Bell Aircraft since 1935
General characteristics
Performance