The legendary B-17 American heavy bombers were rightly called Flying Fortresses. This four-engined heavy bomber was an all-metal hero, an extremely durable aircraft that could return to the airfield with just one engine, riddled with bullets.
But the early models of the B-17 had a significant blind spot in the rear, so fighter support was required. To solve this problem, the B-17E was produced, and a turret with two 12.7mm machine guns was installed in the tail section of the aircraft. To do this the fuselage size had to be increased. In addition, to improve control of the plane, the tail was broadened and a larger vertical fin was installed.
Although it lost some speed when compared to the B-17D, the new model faired favorably with its new protection and thus became the first truly mass-produced B-17. From September 5, 1941 to May 1942, 512 aircraft were made on the production line, before the development of the B-17F.