Bratukhin B-11

The Bratukhin B-11 was a prototype Soviet twin-rotor transport helicopter and the last design of the Bratukhin aircraft design bureau to be built.[1]

B-11
Top view of a B-11.
Role Transport helicopter
National origin Soviet Union
Manufacturer Bratukhin
First flight 1948
Number built 2

Development

The B-11 was similar to the design bureau's earlier B-5, a twin-rotor helicopter, with each rotor driven by an Ivchenko AI-26 radial engine.[1] Each engine was housed in a pod on an outrigger with the related rotor above.[1] Designed for a 1947 air force design competition for a general-purpose helicopter. Two prototypes were built and flown in June 1948, test flights showed a problem with rotor-blade stall at high speed and high resonant vibrations in the whole helicopter.[2] In August 1948 the first prototype was grounded for investigation, but limited testing carried on with the second to find the causes of the problems.[2]

On 13 December 1948 a blade on the right-hand rotor of the second prototype broke, and the subsequent crash killed the two crew.[2] The prototype was then re-designed and re-built to overcome the problems, but when flying resumed in 1949 the stall occurred again.[2] Bratukhin further modified the helicopter in May 1950 with new rotor blades, but development was soon abandoned, and soon after the design bureau was closed down.

Specifications

Data from [1]

General characteristics

  • Crew: 3
  • Length: 9.76 m (32 ft 0 in)
  • Empty weight: 3,398 kg (7,491 lb)
  • Max takeoff weight: 4,510 kg (9,943 lb)
  • Powerplant: 2 × Ivchenko AI-26G(F) radial piston engine
  • Main rotor diameter: 2× 10.00 m (32 ft 10 in)
  • Main rotor area: 74.71 m2 (804.2 sq ft)

Performance

  • Maximum speed: 155 km/h (96 mph, 84 kn) at 1500m (4920ft)
  • Range: 328 km (204 mi, 177 nmi)
  • Service ceiling: 2,550 m (8,370 ft)
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See also

Related development

Related lists

References

Notes
  1. Orbis 1985, p. 839
  2. Nemecek 1986, pp. 386-387

Bibliography
  • Nemecek, Vaclav (1986). The History of Soviet Aircraft from 1918. London: Willow Books. ISBN 0-00-218033-2.
  • The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.
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