Boeing B-17 Flying Fortress

One of the most famous bomber aircraft of World War 2, the B-17 Flying Fortress was used in all theatres of war. One of the most famous Flying Fortresses was the Memphis Belle which was the first B-17 to complete it's tour of twenty five combat missions over Europe.

Responding to the specification released by the US Army in May 1934 calling for a multi-engine bomber which was able to carry a bomb load of 2,000lb over between 1,020 and 2,200 miles at a speed of 200 – 250 mph, with a deadline of August 1935 for a prototype of the plane to be ready for testing. Boeing submitted Model 299 which would be powered by four engines, design of the plane began midway through June 1934. And just over a year later on the 16th July 1935 at Boeing Field, Seattle the plane was introduced to the press, with the headlines the next day proclaiming a '15-ton Flying Fortress' leading to Boeing registering it as the Model 299 name.

Twelve days later on the 28th July 1935 the Boeing B-17 Flying Fortress made it's first flight, before being flown to Wright Field, Ohio for testing and evaluation a few weeks later. By making this flight the B-17 met two objectives of the US Army specification, firstly the journey was 2,100 miles long and was done at an average speed of 252 mph, which boded well for future testing. The prototype comprised armament of five machine guns and could carry more than double the required bomb load of 2,000lb with a 4,800lb maximum load and was powered by four 750-hp Pratt & Whitney R-1690 radial engines. However during testing a setback occurred on the 30th October 1935, when the prototype crashed on take-off, an investigation was to later conclude that the controls had been locked when take-off was attempted. Despite this setback the USAAC ordered thirteen YB-17s (later to be called Y1B-17s) as a result of the successful testing before the accident.

The 2nd December 1936 saw the first Y1B-17 fly, with a few improvements compared to the prototype, the plane would now be powered by 930-hp Wright GR-1820-39 Cyclone radials and could accommodate nine crew members. The USAAC's 2nd Bombardment Group based at Langley Field, Virginia received twelve Flying Fortresses during the first eight months of 1937. The other Y1B-17 of the thirteen originally ordered was sent for further testing at Wright Field. A fourteenth example had also been built for testing the strength of the airframe but was later fitted with 1,000-hp engines with turbochargers and after initial problems it finally flew on the 29th April 1938 with an improvement on it's maximum altitude and speed. With further testing providing the USAAC with proof that turbocharged engines were far more superior than normally aspirated engines, turbocharged engines would become standard on every future version of the B-17 Flying Fortress. As this new version was the first variant to enter operational service it was designated the B-17A. Following shortly after the B-17A was the B-17B, which whilst almost identical to the B-17A featured flaps and a large rudder. This first flew on the 27th June 1939 and just over a year later on the 21st July 1940 the new B-17C flew with 1,200-hp engines and two more machine guns, so the Flying Fortress was now protected by seven machine guns.

It was with the RAF that the Boeing B-17 Flying Fortress was to first experience combat during World War 2, designated Fortress I, twenty B-17C's equipped No. 90 Squadron during early 1941. On the 8th July 1941, they took part in their first RAF raid against the naval barracks at Wilhelmshaven, however bombing from 30,000ft they failed to hit the target. Over the next two months another 26 attacks were made on various German targets, and with eight Fortress I's lost due to combat or accidents the Fortress I proved unsatisfactory for use by Bomber Command for daylight bombing. The remaining Fortress I's were transferred to Coastal Command. As a result of the poor performance of the B-17 over Europe a number of areas where the plane could be improved were found, these included more defensive armament to combat attacks from Messerschmitt BF 109E and 109F fighters and a higher service celling.

By the end of 1941, the US was drawn into the Second World War after the Japanese attack on Pearl Harbour on the 7th December 1941. However large numbers of B-17 Flying Fortresses were sent to Britain to equip the USAAF's 8th Air Force, whilst the RAF were bombing by night the US were bombing by day.

Despite the introduction of the B-17D with additional armour and self-sealing tanks and the B-17E which after the operational experience of the RAF resulted in a major overhaul of the planes design leading to thirteen more machine guns mounted in three turrets, two power operated and one manual operated, in the nose, radio compartment and waist of the plane. This new variant flew for the first time on the 5th September 1941. The USAAF first raid over Europe was on the 17th August 1942 when eighteen Boeing B-17E Flying Fortresses escorted by Supermarine Spitfire's of the RAF attacked the marshalling yards at Rouen-Sotteville in France, only two aircraft sustained minor damage and the mission was a success.

Flying for the first time on the 30th May 1942, the B-17F featured a redesigned nose, more armour and increased fuel capacity. Along with the B-17E it would be the Fortress versions most extensively used by the 8th Air Force. However mounting losses during the daylight raids were to show that the Flying Fortress either on it's own or flying in formation could not defend themselves. Although the B-17G appeared with a gun turret in the nose section to limit the planes vulnerability to head on attacks, daylight raids deep into Germany were suspended, due to heavy losses. The introduction of the North American P-51 Mustang and Republic P-47 Thunderbolt equipped with external fuel tanks saw these missions resume and losses were reduced.

The Boeing B-17 Flying Fortress was used wherever US forces were. In the Pacific theatre of war they were used for close-support bombing, patrol and reconnaissance. A few B-17's were produced for special operations and purposes and despite production totalling 12,731, only a few hundred would stay in service at the conclusion of World War 2.

A B-17G is on display at RAF Museum London, Hendon

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Two B-17Gs are on display at IWM Duxford, including Sally B

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