The BOK-1 (Byuro Osobykh Konstrooktsiy - bureau of special design), (a.k.a. SS (Stratosfernii Samolyet – stratospheric aircraft)), was an experimental high-altitude aircraft designed and built in the USSR from 1934.
| BOK-1 | |
|---|---|
| Role | High-Altitude research aircraft Type of aircraft |
| National origin | Soviet Union |
| First flight | summer 1936 |
| Number built | 1 |
| Developed from | Tupolev RD |
The BOK was formed as part of TsAGI (Tsentrahl'nyy Aerodinamicheskiy i Ghidrodinamicheskiy Institoot- central aerodynamics and hydrodynamics institute) on the orders of the Soviet Revolutionary Military Council in Dec 1930. One of the first tasks of BOK was to design and build the hermetically sealed gondola of the SSSR-1 high-altitude balloon. BOK engineers were sent to the Junkers factory at Dessau to study the Junkers Ju 49 which was the first aircraft fitted with a sealed cabin for high-altitude flight. The gondola for the SSSR-1 was designed, built and flown successfully to an altitude of 18,000m in 1933. The BOK was then assigned the task of applying the 'hermetic' cabin to an aircraft with the Tupolev RD chosen as the basis of the BOK-1. A sealed 1.8 m3 cylindrical cabin constructed from 1.8–2 mm (0.071–0.079 in) D1 light alloy was fitted to a modified RD airframe.
The cabin had convex bulkheads front and rear with the main entry hatch in the roof and emergency exit through a porthole at the rear. Seven portholes gave sufficient vision with five for the pilot and two for the radio operator/observer. A maximum design pressure differential of 0.22 kg/cm2 (3.2 lb/in2) held the cabin altitude at 8,000 m (26,000 ft) up to the aircraft ceiling of 14,000 m (46,000 ft). With the cabin structure sealed, cabin air was dumped overboard at a controlled rate through a dump valve and replaced with oxygen, from storage bottles, maintaining oxygen levels roughly constant. Heating was supplied through radiators in the engine cooling circuit, to keep the cabin between 15 and 18 °C.
The RD airframe was modified with reduced span wings, restressed structure for lower gross weight, fixed spatted single mainwheels, an M-34RN engine and three-bladed propeller, and later an M-34RNV engine and four-bladed propeller. Built at GAZ-35 the BOK-1 was first flown by I.F. Petrov in the summer of 1936 and reached a maximum altitude of 14,000 m in 1938.
Data from Gunston, Bill. “The Osprey Encyclopaedia of Russian Aircraft 1875–1995”. London, Osprey. 1995. ISBN 1-85532-405-9
General characteristics
Performance
Aircraft of comparable role, configuration, and era
Related lists
Soviet miscellaneous aircraft designations, 1923–1940 | |
|---|---|
| Autogyro (A) |
|
| Arctic aircraft (ARK) | |
| Cruiser flying boat (MK) | |
| Overhead tank destroyer (VIT) | |
| Descriptors | |
1 Not assigned | |