TB-3 / ANT-6, A.N.Tupolev

Those images (~30k) appear in an article "Vakhmistrov's Zveno" posted at Alexej Gretchihine Russian Aviation Page

ngular mid-wing monoplane with fixed landing gear. A four-engined development of the TB-1. Frequently used designation TB-3-AM-34RN corresponds to TB-3 with modified Mikulin AM-34RN engines. For some time, the USSR had the largest heavy bomber force in the world and the TB-3 was one of the most impressive heavy bombers. Used as a "mother aircraft" in Zveno experiments.

There was a project of turboprop powered modification with GTU-3 engines as early as 1938-39!

Many were lost during Nazi surprise attack while on the ground, as well as during first weeks of the War due to complete obsolecense and lack of escort fighters. In WWII some were used as transports; they were retired after 1942.