Bell H-12

The Bell R-12 (Model 48) was an American 1940s military utility helicopter built by Bell Helicopter company.

Development

During 1946 Bell Helicopter began development of a new helicopter, much larger, than Model 47. It was partly basing upon its construction, first of all, a rotor system, and was basically a scaled-up version of Model 47. The basic variant was civilian Model 42, but the United States Air Force got interested in the design and ordered development of its military variant, Model 48. Two prototypes were ordered as the XR-12. It was powered by a 540 hp Pratt & Whitney R-1340-AN-1 radial engine and seated five. A production batch of 34 helicopters was ordered, under a designation R-12A, but it was cancelled afterwards. Another enlarged prototype (the XR-12B, Model 48A) with seats for eight and a more powerful 600 hp R-1340-55 engine was also ordered. It was followed by ten pre-series helicopters YR-12B, with a redesigned cabin, with a glazed nose, instead of car-like nose^[1]. With a change in designation system the helicopter was re-designated the H-12. Test were not satisfactory, there were initially problems with the main rotor, and none were ordered.

Variants

XR-12

prototype, redesignated XH-12, two built.

R-12A

production version, 34 on order cancelled.

XR-12B

prototype with more powerful engine and increased seating, re-designated XH-12B, one built.

YR-12B

as XR-12B but with R-1340-55 engines, re-designated YH-12B, ten built.

XH-12

XR-12 re-designated in 1947.

XH-12B

XR-12B re-designated in 1947.

YH-12B

YR-12B re-designated in 1947.

Operators

 United States

• United States Air Force

Specifications (XR-12B)

General characteristics

• Crew: 2
• Capacity: 8
• Length: ft (12.06 m )(fuselage)
• Rotor diameter: 47 ft 6 in (14.48 m)
• Height: ft (3.43 m)
• Disc area: 1,772 ft² (164.62 m²)
• Loaded weight: lb (2854 kg)
• Max takeoff weight: 6,286 lb (2851 kg)
• Powerplant: 1 × Pratt & Whitney R-1340-55 Wasp radial piston, 600 hp (447 kW)
• Propellers: 1 rotor, 1 per engine

Performance

• Maximum speed: 105 mph (169 km/h)
• Cruise speed: 90 mph (145 km/h)
• Range: 300 miles (483 km)
• Service ceiling: ft (3960 m)
• Rate of climb: ft/s (2.28 m/s)

See also

Related development

• Bell Model 47
• Bell Model 42
• Agusta-Bell AB.102
  

Aircraft of comparable role, configuration and era

• Sikorsky H-19
  

References

• Andrade, John M. U.S.Military Aircraft Designation and Serials since 1909. Leicester, UK: Midland Counties Publications, 1979. ISBN 0-904597-22-9.
• The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). London, Orbis Publishing.
• Bell Model 48 retrieved 2-6-2008

External links

• Copter Ferry Hops To The Front, December 1950, Popular Science large and detailed article with rare photos