Boeing B-17 Flying Fortress 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 against Douglas and Martin for a contract to build 200 bombers, the Boeing entry (prototype Model 299/XB-17) outperformed both competitors and exceeded the air corps' performance specifications. Although Boeing lost the contract (to the Douglas B-18 Bolo) because the prototype crashed, the air corps ordered 13 more B-17s for further evaluation. From its introduction in 1938, the B-17 Flying Fortress evolved through numerous design advances, becoming the third-most produced bomber of all time,
Military history of the United Kingdom during World War II fastest fighter became one of the central themes of World War II. The RAF underwent rapid expansion following the outbreak of war against Germany in 1939. This included the training in Canada of half of British and Commonwealth aircrews, some 167,000 men in all. The RAF also integrated Polish and other airmen who had escaped from Hitler's Europe. The combined bomber offensive was born out of the need to strike back at Germany during the years when the United Kingdom had no forces on the continent of Europe. Initially the bomber forces available for attacks were small, and the rules