Bolkhovitinov DB-A / DBA / DB-2A
A decision was made to fly non-stop from Moscow to the USA and the DB-A was modified to fly, at an overload weight of 34,700 kg (76,500 lb), carry enough fuel to fly 8,440 km (5,244 miles). The red painted DB-A prototype under command of Sigizmund Levanevsky departed Moscow Shchyelkovo airport on the 12th of August 1937 on an attempt to fly to Fairbanks, Alaska. After 14hrs 32min the crew sent a radio message that one engine had failed and gave a revised ETA for Fairbanks, but nothing further was heard from the DB-A and the fate of the aircraft and crew remains a mystery.
A second aircraft with increased gross weight, improved airframe, re-designed nose and more power was completed and flown in March 1936 as the DB-2A. An order for 16 aircraft was placed late in 1937, with the designation DBA, but only twelve were completed due to the advent of the TB-7/Pe-8.
DB-A – The initial prototype aircraft, with M-34RN engines, lost on a non stop flight Moscow to Fairbanks, Alaska.
DB-2A – The second prototype with many detail improvements and M-34RNV engines.
DBA – Production aircraft ordered in 1937. Sixteen aircraft ordered, but only twelve completed, with M-34FRN engines plus turbo-chargers, rearwards retracting main undercarriage, gunners cockpits in the rear of the inner engine nacelles, and other modificatoions.
TK-1 TK ( - heavy cruiser) – Projected escort bomber with 11 crew, 3xShVAK + 3,000 rounds, 5xShKAS + 11,000 rounds and underwing rockets.