Tupolev SB 2 M 103 late model

The Tupolev ANT-40, also known by its service name Tupolev SB (Russian: Скоростной бомбардировщик – Skorostnoi Bombardirovschik – high speed bomber) and development co-name TsAGI-40, was a high speed twin-engined three-seat monoplane bomber, first flown in 1934. The Tupolev design was advanced but lacked refinement, much to the dismay of crews, maintenance personnel, and Stalin, who pointed out that "there are no trivialities in aviation".

Numerically the most important bomber in the world in the late 1930s, the SB was the first modern stressed skin aircraft produced in quantity in the Soviet Union and probably the most formidable bomber of the mid-1930s. It was produced in the Soviet Union and was also built under license in Czechoslovakia. Many versions saw extensive action in Spain, the Republic of China, Mongolia, Finland and at the beginning of World War II against Germany in 1941.

Later version with water cooled inline engines.