OKB-1 140 - Development

Development

The '140' was a reconnaissance/bomber aircraft, derived from the OKB-1 EF 131 with home-grown Soviet turbojet engines. The initial version, a tactical jet bomber, with a secondary reconnaissance role, was initiated as the EF-140 by Dr. Brunholf Baade, at OKB-1, in 1947. The six Jumo 004 engines of the EF-131 were replaced by two Mikulin AM-TKRD-01 axial flow turbojets, rated at 32.372 kN (7,280 lb) thrust, in large nacelles attached to the underside of the wing at the same position. Using the airframe of the second EF-131 prototype, the '140' was very similar in appearance, with the classic Junkers style crew compartment in the nose, wings swept forward 19deg50min with marked dihedral, and the under-slung engine nacelles extending forward of the leading-edge. Construction was of aluminium alloy stressed skin, with a semi-monocoque fuselage, wings with multiple spars covered with stressed skin panels, and high strength steel for highly stressed parts. Defensive armament consisted of a VDB-6 dorsal and NDB-1M ventral remotely controlled turrets controlled by the gunner, in the rear of the crew compartment, using upper and lower periscopes. The prototype was completed quickly and ready for flight tests by late September 1948 after being disassembled and transported to Tyoplyy Stan airfield on the outskirts of Moscow. First flight took place on 30 September 1948, but early test flights were disrupted by severe problems with the fuel control units of the AM-TKRD-01 engines. A replacement ship-set were fitted and testing continued till manufacturers test were completed on 24 May 1949.

Council of Ministers directive No. 1886-696 called for development of 140 as a tactical reconnaissance aircraft powered by two Klimov VK-1 centrifugal flow turbo-jets. During the design work for the '140-R' the deficiencies highlighted by flight testing of the '140' were addressed as well as the addition of wing-tip mounted fuel tanks and new nacelles for the VK-1 engines, and the fitting of DT-V1 and DT-N1 turrets, replacing those of the '140', armed with 2 × 23mm cannon each. Flight testing of '140-R' commenced on 20 October at a specially built airfield near the GOZ-1 factory at Borki, (the German workers were not admitted to Tyoplyy Stan for security reasons), where four flights were carried out, all of which suffered from severe vibration of the wings.

The final variant of '140' was the '140-B/R', which was a reconnaissance bomber, powered by the same engines but with increased weights and reduced performance. Design work, static tests, construction were complete and ground testing of the aircraft partially completed when all work on '140-R' and '140-B/R' aircraft was terminated by Council of Ministers directive No. 2474-974 issued on 18 June 1950.