B-17

U.S. B-17, or Flying Fortress also called Flying Fortress, U.S. heavy bomber used during World War II. The B-17 was designed by the Boeing Aircraft Company to specifications written in 1934. A prototype flew in 1935, and the craft was in small-scale production in 1937. The seventh substantial variation of the original design, the B-17G, was equipped with superchargers to allow it to cruise at 35,000 feet (10,670 m) at a maximum speed of 287 miles per hour (462 km/h). It was called the Flying Fortress because of the .50-calibre machine guns, 13 in all, that bristled from every corner. It could carry 6,000 pounds (2,720 kg) of bombs in its bomb bays and more on racks under the wings. With production augmented at two other plants, Douglas and Lockheed, Boeing turned out 12,731 Flying Fortresses, nearly all of which were used by the U.S. forces for high-level daylight bombing over Europe. The airplane's formidable arsenal led to the development of a highly effective defensive tactic: on a bombing mission, B-17s would form a large square, enabling their gunners to pour withering cross fire on intruding fighters.