Tupolev SB

The Tupolev SB, formally the ANT-40 and also known as TsAGI-40, was a Soviet high-speed twin-engined, three-seat monoplane bomber that first flew in 1934. Designed in the Tupolev design bureau by a team led by A. A. Arkhangelski, it was the first modern stressed-skin aircraft built in quantity in the Soviet Union and, by the late 1930s, the most numerous bomber in the world. Its speed let it outpace most of the biplane fighters it met in the Spanish Civil War, where Soviet-supplied SBs earned the nickname Katyusha, and versions also fought in China, Mongolia, Finland and at the start of the German invasion in 1941, by which time faster fighters had made it obsolete. Production ran from 1936 to 1941 at Moscow and Irkutsk, with licence-built Avia B-71 aircraft in Czechoslovakia, for a total of about 6,945 built according to the article text. Civil, trainer and other secondary versions were also flown, and the design led to the Arkhangelsky Ar-2 dive bomber.