A three-seat, all-metal monoplane with a retractable landing gear system including a tail wheel.
This aircraft was designed in the Department of Aviation, Hydroaviation and Aircraft Prototype Engineering (AGOS) of the Central Aerohydrodynamic Institute (TsAGI) under the direction of A. N. Tupolev and A. A. Arkhangelski. A prototype ANT-40-1 made its first flight on 7 October 1934. Full-scale production of the aircraft under the designation of SB (meaning "High-Speed Bomber") was launched in February 1936.
When creating the new aircraft, the designers paid much attention to the plane's aerodynamic superiority, considering this one of the most important components necessary to obtain high speed. Many structural and technological decisions were made to improve the plane's aerodynamics. It was the first time that an aircraft of this class had smooth metal skin instead of more rigid, corrugated skin; also, new high-strength materials were introduced, flush riveting used, retractable landing gear installed, and crew cockpits enclosed. The SB included the most advanced achievements in the field of aerodynamics, aircraft materials, and technology. As a result, during tests, the ANT-40 prototype nearly matched the maximum speed of the I-16 fighter.
The first production SB planes had 750 hp Klimov М-100 twelve-cylinder, V-type, liquid-cooled engines (a licensed version of the French Hispano-Suiza 12Ybrs engine).
The engines were fitted with cowls featuring a frontal circular radiator which was completely covered by movable shutters which regulated the incoming air flow. The first production SBs were equipped with two-bladed, fixed-pitch metal propellers.
The SB's defensive armament included three gun posts: a starboard post, an upper post, and a hatch post. The starboard mount in the navigator's cockpit consisted of two 7.62 mm ShKAS machine guns with a total magazine capacity of 1,900 rounds. The TUR-9 upper turret was equipped with one ShKAS machine gun whose magazine capacity was 1,000 rounds. The LU hatch mount, with one ShKAS machine gun carrying 500 rounds, was intended for cover the aircraft's lower rear. All of the machine guns were belt-fed, which was also was a revolutionary innovation: the rest of the world mostly continued to use detachable magazines.
The bombing armament of the first-series SBs was housed only inside the bomb bay, on two DER-33 horizontal racks (on which FAB-500 or FAB-250 bombs could be suspended) or four DER-34 vertical racks (for FAB-100 bombs or bomb clusters). The plane's maximum bomb capacity was 600 kg (6 FAB-100 bombs, suspended vertically).