Tupolev DB-1

The Tupolev DB-1 was a Soviet long-range bomber developed in the 1930s. It was developed from the Tupolev ANT-25 distance record-breaking aircraft. Development was prolonged and it was recognized as obsolete by the time it was in production. Only eighteen were built and all were withdrawn from service in 1937.

Development
The possibilities of exchanging some of the fuel of the ANT-25 for bombs and/or cameras was recognized early in its development and the VVS issued a requirement for an aircraft to carry 1000 kg over an operational radius of 2000 km at a speed of 200 km/h. The Tupolev OKB had prepared a design and built a mock-up by August 1933, using the internal designation of ANT-36, and the VVS approved both. Series production of a first batch of 24, out of a planned total of 50, was initiated in the new Factory No. 18 at Voronezh in 1934, but only a total of 18 were built before the program was canceled.

The airframe, engine and crew compartments were retained from the ANT-25 almost unchanged, although the co-pilot's and navigator's positions were each given one 7.62 mm DA machine gun for defense. The DB-1 (long-range bomber model 1), as it was designated in VVS service, was given a smooth skin and a bomb bay was built in the wing center section that carried ten 100 kg FAB-100 bombs nose-up. An AFA-14 camera was mounted in the rear cockpit, but other cameras could be carried in lieu of the bombs.

Operational history
The DB-1's first flight was in 1934, but the first production aircraft wasn't tested until the autumn of 1935. It was rejected by the VVS because of poor manufacturing quality. Only ten aircraft were placed into service by the VVS which equipped one regiment based near the factory at Voronezh. All of these were retired by the VVS in 1937.

Variants
The remainder of these aircraft were used for a variety of tasks. One was fitted with the first flight-cleared Charomskii AN-1 diesel engine for flight testing. The change in the center of gravity caused many problems and the undercarriage had to be made non-retractable. Two others were selected in 1938 for distance record attempts with all-female crews, but an Ilyushin DB-3 was ultimately chosen instead.