SB-3Ant-2_Tupolev

Soviet twin-engine bomber was the backbone of VVS before and beginning of the Second World War, also participated on the Republican side during the Spanish Civil War, making long "Raids" to surprise bombing nationalists entering from the rear, at the time and thanks to its high speed acted almost total immunity due to lack of nationalist fighters with benefits in speed and climbing ability that locate in unique position to intercept these quick and elusive bombers, it is worth noting the weapons warehouse just behind the cockpit with vertical pumps (something also seen in the Heinkel He-111 bombers and bombers later in the Yak-9) to me in what I think is particularly strange and unorthodox, but stood behind the dorsal and ventral gunner attached to the bow that completed their defensive armament, two 12-cylinder engines water cooled radiators with individual bushings between bi-blade propellers and engine ( Another feature seen in aircraft of the First World War) had fully retractable landing gear, lacked self-sealing tanks which made ​​him easy prey once reached with few shots and had a large wing area in cutaway appreciable, unidentified author and taken from the web: