Boeing YB-40 Flying Fortress Boeing YB-40 Flying Fortress The Boeing YB-40 Flying Fortress was a modification for operational testing purposes of the B-17 Flying Fortress bomber aircraft, converted to act as a heavily armed gunship for other bombers during World War II. At the time of its development, long-range fighter aircraft such as the North American P-51 Mustang were just entering quantity production, and thus were not yet available to accompany bombers all the way from England to Germany and back. Work on the prototype, Project V-139, began in September 1942 by converting the second production B-17F-1-BO (serial number 41-24341) built. Conversion work was
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