Dieselpunks.org | February 9, 2013
An outstanding mid-30s flying machine which became obsolete by the start of WWII
The two ANT-40 light bomber prototypes of Andrei N. Tupolev’s design bureau, designed and developed by a team led by A. A. Arkhangelski, 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 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. The version of the SB to be supplied to, and subsequently license-built as the Avia B-71 was fundamentally the SB 2M-100A but fitted with the Avia-built Hispano-Suiza 12-Ydrs engine. A single 7.92 mm ZB-30 machine gun supplanted the twin ShKAS machine guns in the nose and similar weapons were provided for the dorsal and ventral stations.
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.