A Strange B-17 flying fortress
B-17, also called Flying Fortress, U.S. heavy bomber used during World War II. The B-17 was designed by the Boeing Aircraft Company in response to a 1934 Army Air Corps specification that called for a four-engined bomber at a time when two engines were the norm. The bomber was intended from the outset to attack strategic targets by precision daylight bombing, penetrating deep into enemy territory by flying above the effective range of antiaircraft artillery. Turbo-supercharged radial engines (a uniquely American development) were to give the necessary high-altitude performance, and heavy defensive armament was to provide protection against attacking fighters. Accuracy was to be achieved with the Norden bombsight, developed and fielded in great secrecy during the 1930s. The Norden consisted of a gyroscopically stabilized telescopic sight coupled to an electromechanical computer into which the bombardier fed inputs for altitude, atmospheric conditions, air speed, ground speed, and drift. During the bomb run, the sight was slaved to the automatic pilot to guide the aircraft to the precise release point. In the hands of a skilled bombardier, the Norden was a remarkably accurate sight. The first prototype bomber flew in mid-1935, and the B-17 entered small-scale production in 1937. Early versions proved to be more vulnerable to fighter attack than anticipated, but, by the time the B-17E version began to go into service shortly before the United States entered the war in 1941, the plane was equipped with turrets in the upper fuselage, belly, and tail. All but the last turret were power-operated, and each mounted a pair of 0.50-calibre (12.7-mm) machine guns. This increased firepower made the B-17 a formidable opponent for enemy fighters, particularly when flying in tightly stacked defensive formations for mutual protection. The basic element of a typical formation was a squadron “box” of 9 or 12 aircraft; three squadron boxes staggered vertically and horizontally formed a group, and three groups in trail formed a combat wing. In the event, the need to keep such tight defensive formations over Europe compromised the accuracy of the Norden bombsight, since individual bomb runs were not possible without breaking the formation. Whole bomb formations had to drop their loads on the lead bombardier’s command, and the inevitable small differences in timing and heading led to dispersed bomb patterns.
The Boeing B-17 Flying Fortress and the Consolidated B-24 were the United States’ two standard heavy bombers until the arrival of the Boeing B-29 Superfortress in 1944. The B-17 served in almost every theater of World War II, but it was used mostly by the US Eighth Air Force, based in the UK, to bombard German targets. The first missions were in daylight hours to improve accuracy, but this strategy plus a lack of adequate fighter coverage, resulted in very heavy losses of aircraft and crew. Its first bombing mission was with the RAF as Fortress Is, but it was hardly ready for war. As refinements progressed, along with better pilot training and tactics, it became a formidable weapon in the Allied war against Germany.
The Flying Fortress was designed in response to a USAAC competition, announced on August 6, 1934, to find a modern replacement for the assorted twin-engine Keystone biplane bombers and greater performance than the Martin B-10. While the performance of the B-10 was considered adequate at the time, the Keystones lumbered along at about 115 mph (185 km/h), were very unmaneuverable, lightly armed and carried only a limited bomb load.1 The requirement was for a multi-engine bomber to be used for coastal-defense.
Specifications required were:
Range of at least 1,020 miles (1,640 km).
Speed of 200 to 250 mph (322 to 402 km/h).
Bomb load of 2,000 lb (907 kg).
A Boeing design team began work on the Model 299 prototype in June 1934 and construction began in August of the same year. The most significant rival to the Model 299 was the Douglas DB-1, which was based on the Douglas DC-2. The third competitor was the Martin 146.
Read more here : http://www.aviation-history.com/boeing/b17.html
The Strange B-17 that terrified the Luftwaffe
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Credit to : FlakAlley