Tupolev ANT-40 / SB-2 / Ar-2
|BOMBER||Virtual Aircraft Museum / USSR / Russia / Tupolev|
The two ANT-40 light bomber prototypes of Andrei N. Tupolev's design bureau were years ahead of their time when they first flew in October 1934: the all-metal construction, enclosed cockpit and retractable landing gear were then comparatively novel features. Indeed the ANT-40's maximum speed of 325km/h at operating height was faster than the biplane interceptor fighters that equipped most of the peacetime air forces. The initial production version as selected for export and service with the V-VS was based on the second prototype, and was known as the Tupolev SB-2 (skorostnoi bombardirovshchik, or fast bomber); the engines were two 619kW licence-built Hispano-Suiza 12Ybr engines, termed M-100 by Soviet industry, and initially they were fitted with two-bladed fixed-pitch propellers. The first SB-2s were passed to the V-VS's bomber aviation regiments in February 1936, and in October of that year the first of 210 were transferred with Soviet crews to Spain to fight on the side of the Republican air force against the insurgent Nationalists. Over Spain the performance of the SB-2 caused considerable concern to the Nationalist fighter units which were equipped with Heinkel He-51 and Fiat CR.32 biplanes, and the urgent call went out for fighters of better speed and climb properties. At the time SB-2s were passed to the Chinese Nationalist air force to fight aganst the Japanese, and to Czechoslovakia, where the type went into licensed manufacture as the B.71 bomber. In general the SB-2 performed well until faced with sterner fighter opposition, which occurred over Spain in 1938 and in particular over Finland during the Winter War of 1939-40, when many were shot down. Steps were taken to improve performance by installing the 641kW M-100A engine with variable-pitch propellers. Increased fuel capacity and two 716kW M-103 engines were installed in the Tupolev SB-2bis, the performance of which was improved by three-bladed VISh-22 propellers. In addition to the PS-40 and PS-41 transport versions the SB-RK (Arkhangelskii Ar-2) was a modified SB-2bis dive-bomber with reduced wing area and powered by two supercharged M-105R engines. The SB-2's record as a day bomber came to an abrupt end during the fierce fighting following the German invasion of the USSR on 22 June 1941. Those that were not destroyed on the ground ventured into the air on numerous and gallantly-flown missions over the front line, and paid a heavy price to the Luftwaffe's Messerschmitt Bf 109F fighters. Thereafter the SB-2 and SB-2bis bombers were relegated to night work with the V-VS and the Soviet naval air arm. Production amounted to 6,967 of all marks.