Ilyushin Il-4
The Ilyushin Il-4 (DB-3F) (Russian: Ильюшин Ил-4 (ДБ-3Ф); NATO reporting name: Bob) is a Soviet twin-engined long-range bomber and torpedo bomber, widely used by the Soviet Air Force and Soviet Naval Aviation during World War II. == Design and development == In 1938, the Ilyushin design bureau redesigned the Ilyushin DB-3 to ease production and improve its performance, the revised version receiving the designation DB-3F (Forsirovanniye or "boosted"). The aircraft's internal structure, particularly the wings, was extensively changed, eliminating the need for hand finishing of the structure, and with duralumin replacing the large scale use of steel in the earlier version.