Boeing B-17 Flying Fortress NAN10-50.jpg|thumb|B-17 modified for testing of the [[Pratt & Whitney T34|XT-34 turboprop]]. When testing concluded, the aircraft was restored to stock configuration as the "[[Liberty Belle (B-17)|Liberty Belle]]", but was lost in a post-forced-landing fire near [[Oswego, Illinois]] on 13 June 2011.]] [[Category:Boeing aircraft|B-17 Flying Fortress]] [[Category:United States bomber aircraft 1930–1939]] [[Category:Four-engined tractor aircraft]] [[Category:Low-wing aircraft]] [[Category:World War II bombers of the United States]] [[Category:Boeing B-17 Flying Fortress| ]] [[Category:Aircraft first flown in 1935]] Boeing B-17 Flying Fortress The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Competing
31st Flying Training Wing (World War II) for most of its operational service, it controlled contract pilot schools primarily in the Central United States. Until 1939, the Army Air Corps provided all flying training with military instructor pilots. Beginning in 1939, it contracted with nine civilian flying schools to provide primary flight training. Primary training consisted of a three-month course of 65 hours of flying instruction. As the United States prepared to enter World War II by expanding its number of flying squadrons, the number of contract primary schools increased. According to the contract, the government supplied students with training aircraft, flying clothes, textbooks, and equipment. The