Bratukhin B-11
| Bratukhin B-11 | |
|---|---|
| 300px | |
| Top view of a B-11. | |
| Role | Transport helicopter |
| National origin | Soviet Union |
| Manufacturer | Bratukhin |
| First flight | 1948 |
| Number built | 2 |
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]
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 (8,366 ft)
See also
- Related development
- Related lists
References
Notes
Bibliography
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