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BOK / Bureau of Special Constructions / Bureau Osobykh Konstruktsii
Bureau Osobykh Konstruktsii - Russian: Бюро Особых Конструкций - БОК
The Bureau of constructions created in 1931 as an operating unit within the Central Aero-Hydrodynamic Institute (TsAGI) with VA Chizhevski as director. This group was mainly focused on the development of unusual and record-setting aircraft.
In December 1930, the need to create a special department or a construction bureau for the projection of these aircraft was discussed.
By order of the RevVoyenSoviet of the USSR of the 27 of January of 1931 it was created a new department within the structure of the TsAGI which became designated Bureau of Special Constructions (BOK). The 32-year-old engineer Vladimir Antonovich Chizhevski was appointed head of the new department. As Chizhevski's assistants were selected NN Kashtanov, BI Karmanov, A. Ya. Lievin, II Tsiebrikov, VI Lapinski, VG Florov.
Among the BOK's working directions were the projection of autogyros, the investigations of airplanes with canard surfaces (known in the USSR as the “utka” (duck)), airplanes without a tail or flying wings and in a special way the creation of airplanes for the realization of stratospheric flights. In this sense, the main directions of work were:
Studies of the aerodynamics of high altitude aircraft;
Creation of pressurized cabins for the crew;
Development of the controls and organs of direction of the cabin;
Development of instrumentation for the cockpit;
Creation of comfort conditions for the crew;
Creation of a power plant capable of working reliably in rarefied air conditions and temperatures down to -70ºC.
The first works of the BOK were linked to the creation of the stratospheric plane SS and the sealed gondola for the luggage of the “USSR” stratocrat.
The creation of the BOK practically coincided with the restructuring of the experimental building in the USSR. The 27 of August of 1931 the TsKB and TsAGI were merged into one organization which was named TsKB-TsAGI and controlled directly by the OGPU. ES Paufler was appointed by the control structure and SV Ilyushin as technical director.
For the BOK, this new structure resulted in a problem of territoriality that led to not a few conflicts, since the productive decisions were approved in two territories separated from each other in Moscow. For this reason, the preparation of the gondola for the “USSR” stratostat was developed from October 1931 at Factory No.39 Menzhinski, while the stratospheric plane began to be built at the end of 1932 at the newly created Factory of Experimental Constructions (ZOK) of the TsAGI.
In February 1933 the BOK was fully transferred to the TsKB on the territory of Factory No.39, where construction of the aircraft was continued. The group of workers led by Chizhevski became Brigade No.3 of the TsKB.
In the summer of 1934 again the BOK was forced to move. On this occasion Chizhevski's group was transferred to Smolensk, to the base of Factory No.35, where finally and not without great difficulties, the SS could be finished.
In February 1938 the BOK was again transferred from Smolensk to the Moscow suburb of Podlipki, on the territory of KB-29. The Flight Experiment Station (LIS) KB-29 was dedicated to the development of flight tests and implementation of improvements in the VVS bomber fleet and was subordinated to the People's Commissariat for the Military Industry.
With the BOK's relocation to Podlipki, Chizhevski was appointed lead builder of the KB-29 and NN Kashtanov his replacement. At the same time in KB-29 the “Z” brigade led by the constructor VS Vaxmistrov was organized for the development of combined aircraft and the “D” brigade led by Privalov, dedicated to the study of transferring and launching loads from airplanes, with parachutes or without them.
In 1938 Podlipki continued the development of the BOK-7, BOK-11 and BOK-15 models. At the end of that year Chizhevski began the projection of a passenger variant based on the Ilyushin DB-3 bomber, equipped with a pressurized cabin. A short time later the NKAP proposed to use a Lisunov Li-2 (licensed version of the Douglas DC-3) for this purpose. Ultimately none of the variants came to be realized.
In February 1939 Chizhevski was arrested. Temporarily at the head of KB-29 was designated NN Kashtanov. In March 1939, as head of KB-29, PN Golubkov was appointed, who until then had served as director of Factory No.21. NN Kashtanov was appointed chief builder.
A short time later from Factory No.1 he was assigned to Podlipki A. Ya. Scherbakov, author of the pressurized cockpits for the Polikarpov I-15 and I-153 fighters. From that moment the KB-29 became the experimental organization for the projection and construction of airplanes with pressurized cabins.
In late 1939 the KB-29 was renamed NKAP Factory No. 289 under the leadership of PN Golubkov. The works related to the pressurized cabins were once again the subject of the BOK brigade.
In the first half of 1940, Pavel Osipovich Sukhoi's group moved to Factory No. 289 to develop the I-135 (Su-1) fighter. At this time also Scherbakov modified glider SK-9 of Sergei Korolev to adapt him a liquid reagent RDA-150 engine, making the rocket plane RP-318-1.
In 1940, government decisions cut off various experimental development jobs. By decision of the substitute of the NKAP commissioner for experimental aviation AS Yakovlev, received by the director of Factory No. 289 Golubkov on June 4, 1940, the preparation work for long-haul flights with BOK-15 aircraft was cancelled.
As of June 5, all investigative work related to the pressurized cabins was suspended, with the exception of the covers for the cabins of the BOK-15 copies. The last job related to "special" topics at Factory No.289 was the preparation of the I-153GK fighter.
In 1941 the BOK was dissolved and its employees assigned to the OKB of Pavel Osipovich Sukhoi.
Among the fundamental works of the BOK between 1935 and 1939 we can highlight:
BOK-1. Construction completion and testing;
BOK-2 (TsKB-5). Small experimental aircraft built by S. Krichevski and equipped with an M-11 engine. The BOK-2 was a sectioned wing design and hence it was known as RK or Razreznoe Krylo. This design tested the high lift wing. The BOK-2 was tested between 1935 and 1936.
BOK-3 (TsKB-9). This aircraft began to be built as a passenger plane for short lines with the name IS. Its construction was completed in Smolensk, at the BOK-3 factory, with variations in the exterior shape in relation to the initial project and M-48 power plant.
BOK-4. The information on this tailless aircraft model is unknown for sure. It is said to have been built as a scale model of the Kalinin K-12 tailless aircraft, despite exhibiting little overall resemblance to it.
BOK-5 (TsKB-13). Light flying wing with M-11 powerplant developed by Chizhevski. The BOK-5 projection work began in 1934. A prototype was built which demonstrated excellent flying qualities during tests carried out in 1937 - 1938. Development of the BOK-5 was abandoned after Chizhevski's arrest.
BOK-6. Twin-engine bomber project created using the flying wing formula tested on the BOK-5. The BOK-6 was conceived to use two M-34 radial engines and had to be armed by 6 ShKAS 7.62 mm machine guns and a load of 2000 kg of bombs. The development of this model was stopped due to the arrest of Chizhevski in early 1939.
BOK-7. Originally conceived as a stratospheric reconnaissance aircraft, it ended up being developed as a record-setting aircraft. It began to be projected in 1935 as a development of the BOK-1. It was used on the ground for crew training for the BOK-15.
BOK-8. Conceived as an armed development of the BOK-7 (the second copy). It did not occur.
BOK-10. Exploration version project on the BOK-7. It did not pass the project stage. With this name, a special fabric diving suit was also developed for high altitude flight. Work started in 1935
BOK-11. High altitude bomber developed on the BOK-7. It was used on the ground for crew training for the BOK-15.
BOK-12. Project for a twin - engine version of the BOK-7 conceived as an experimental flying laboratory. A large aperture camera for exploration was planned to be installed in the BOK-12 fuselage. It was never realized.
BOK-13. Project for a high altitude passenger plane with capacity for 6 people developed on the basis of the BOK-7.
BOK-15. A powerful stratospheric plane conceived in 1937 to set a new world record for flight distance. Two copies were built in 1939. The start of the Great Patriotic War prevented the flights from taking place.
KB-29 works from 1939 until its dissolution
Completion of two copies of BOK-15
Experimental modifications to two standard Ilyushin DB-3s with pressurized cabs
Development of pressurized cabins for the Polikarpov I-15 and I-16.
Modifications to the BOK-1.
New landing gear for the BOK-5.
Ski train for the BOK-7.
Armament installation in the BOK-11.
Design of a new wing for the BOK-15.
Development of the BOK-17 project based on the Ilyushin DB-3.

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