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B-17 Flying Fortress, U.S. Heavy Bomber


Photograph
                  of restored B-17 Flying Fortress

National Museum of the USAF

Three-view diagram of B-17 from recognition
                  manual

U.S. Air Force. Via Wikimedia Commons


Boeing B-17E Flying Fortress


Specifications:


Crew

10

Dimensions

103’9” by 67’11” by 15’5”
1.62m by 22.50m by 5.84m

Wing area

1420 square feet
131.9 square meters

Weights

33,280-53,000 lbs
15,096-24,040 kg

Maximum speed      

317 mph at 25,000 feet.
510 km/h at 7620 m

Cruising speed

210 mph
338 km/h
Landing speed 84 mph
135 km/h

Climb rate

22 feet per second
6.7 m/s

Service ceiling

36,600 feet
11,155 m

Power plant

4 1200hp (895kW) Wright Cyclone R-1820-65 Cyclone 9-cylinder radial exhaust-turbocharged engines

Armament

1 nose 0.30 machine gun
2 waist 0.50 machine guns
2 paired dorsal turret 0.50 machine guns
2 paired ventral ball turret 0.50 machine guns
2 paired tail 0.50 machine guns

Bomb load

4,000 lbs (1815 kg) bombs or 820 gallon (3100 liter) bomb bay fuel tanks.

Range

2000 miles at 250 mph (3218 km at 402 km/h) with 4000lb (1800 kg) bomb load.
Up to 3400 miles (5500 km) with reduced bomb load and 400 gallon (1514 liter) auxiliary bomb bay fuel tank.

Maximum fuel

2780 gallons
10,520 liters

Production

12,731 of all types at Boeing Airplane Co, Seattle, WA; Vega Aircraft Corporation, Burbank, CA;
and Douglas Aircraft Company, Tulsa, Oklahoma.
  119 B-17B, C, and D
  512 B-17E
  3405 B-17F
  8680 B-17G

Variants

The B-17B, C, and D lacked tail guns and had a ventral blister rather than the ball turret. They also had smaller tails, which reduced stability for accurate bombing.

Beginning with the 113th production unit, the B-17E replaced the awkward remote controlled ventral ball turret with the Sperry ball turret used in all subsequent versions

The B-17F used R-1820-97 engines giving it an emergency speed of 314 mph (505 km/h), and it added two 0.50 waist guns. It had extra wing fuel cells ("Tokyo tanks") containing 1100 gallons and extending its range by about 1000 miles (1600 km).

The B-17G was the definitive model, with an added chin turret having two 0.50 machine guns for increased forward protection. However, its increased weight (38,000 lbs or 17,000 kg empty) reduced its cruising speed to little better than 160 mph (260 km/h) and its range by about 700 miles (1400 km).

The PB-1W was under development by the Navy at the time of the Japanese surrender. It would have carried a powerful airborne radar and fighter controllers, prefiguring the modern AWACS aircraft.

The B-17 Flying Fortress was the first true strategic bomber and the iconic American heavy bomber of the Second World War. It was an extremely rugged and reliable aircraft, with very sedate handling that allowed many a pilot to bring his badly damaged aircraft home. It was deployed by the thousands to Europe and was the backbone of the strategic bombing campaign against Germany until well into the war. However, the B-17 failed to live up to expectations that it could defend itself in enemy airspace, though it gave the Japanese a harder time than the Germans because the German fighters were armored and much sturdier than Japanese fighters. Its Norden bomb sight was amazingly accurate – in the absence of cloud cover, wind shear, and flak. Under real combat conditions, accuracy varied from fair to abysmal. The B-17 also never lived up to expectations that it could interdict shipping: Its crews found that hitting a moving target from five miles (8 km) up was almost impossible. However, under the right conditions, the B-17 could do massive damage to stationary targets, such as airfields, ports, and troop concentrations.

The aircraft had a long gestation, with elements of the design going back to the 1930 Model 200 Monomail, of which only two were built. Other projects that contributed elements to the design included the Model 215 YB-9 "Death Angel" twin engine bomber, the Model 247 twin engine transport, and the XB-15. Boeing barely recovered its costs on these experimental designs, with the YB-9 losing the Air Corps production contract to the Martin B-10 and the Model 247 losing out to the Douglas DC-2 and DC-3. Boeing took an additional enormous gamble in investing $275,000 in the Model 299, the prototype for the B-17, interpreting the Air Corps request for a "multiengine bomber" to include four-engine designs. The B-17 was dubbed the Flying Fortress by Seattle Times newspaper reporter Dick Williams when the prototype was rolled out for its first flight on 28 July 1935.

Boeing very nearly lost their gamble: When the prototype crashed on 30 October 1935, killing the test pilot, skepticism of the design grew in spite of an investigation showing the crash was due to failure to unlock the control surfaces. Working under the tight budgets of the Great Depression, the Air Corps initially purchased just thirteen YB-17s and allocated the rest of the bomber budget to purchasing 133 of the much cheaper, but also much less capable, B-18. However, many Air Corps officers regarded the B-17 equipped with the Norden bombsight as the embodiment of their doctrine of pinpoint strategic bombing. Thus, the Air Corps and Boeing found a common interest in promoting the new strategic bomber, and the initial thirteen YB-17s were given extensive publicity by both organizations.

An important publicity exercise was the Good Will Missions to South America. The first was flown on 15 February 1938 from Langley Field to Buenos Aires, Argentina, and participants included such future senior officers as Curtis LeMay and Caleb Haynes. The round trip took twelve days, broke records, and won the Mackay Trophty for that year. A second Good Will Mission to Brazil left on November 10.

The aircraft underwent extensive modification over its production run, so that the original B-17 and the B-17G hardly appeared to be the same aircraft. Early improvements included the YB-17A, the first turbosupercharged heavy bomber. The B-17C, which was the first model to see combat, incorporated some but not all of the lessons of the early years of the Second World War, while the B-17E was the first fully modernized model. Delivery of the B-17E was delayed by a dispute over the pricing of the model, and the awkward remote controlled ventral ball turret, which apparently never hit a target in anger, was not replaced with the more practical Sperry ball turret until 112 units had already been delivered Production was greatly expanded in late 1941 when Douglas and Lockheed Vega began manufacturing the B-17F under license. The XB-40, an otherwise unsuccessful escort version, demonstrated the value of a chin turret, and this was adopted for the definitive B-17G, which went into production in mid-1943. Most B-17s were equipped with bombing radar by the beginning of 1944.

As a long-range strategic bomber, the B-17 had a heating system and provisions for heated flight suits for its crew. It had four separate oxygen systems with sixteen outlets, plus walk-around bottles, with a total capacity of 72 man-hours. The crew were protected by patches of armor plating, with the pilots having the most protection (armored seats and forward and aft armored bulkheads and the ball turret gunner the least (a small seat patch).

Two squadrons of B-17s were in the Philippines when war broke out, with additional squadrons on the way. Many of those in the Philippines were the obsolescent C and D models, with their inadequate defensive armament, which were regarded by Boeing and the Air Corps as suitable only for training purposes. The reinforcements were diverted elsewhere (mostly Australia and the Netherlands East Indies) when it became clear that the Japanese were firmly in control of the air over Luzon. Over half of all B-17 crews were deployed to the Pacific during the first year of the war, but by mid-1943 the B-17 was being rapidly replaced by the B-24, whose longer range made it more suitable for the vast distances of the Pacific. The B-17 was also preferred for European service because of its perceived ruggedness and higher service ceiling. By September 1943, the B-17 had been completely withdrawn from regular squadron service in the Pacific, though a small number of B-17s converted to transport or air and sea rescue remained in the theater. No B-17Gs saw regular squadron service in the Pacific, though eight modified SB-16Gs saw service with 4 Emergency Rescue Squadron. Had the war continued longer, the PB-1W with its powerful airborne radar might have seen service in the invasion of Japan.

Though much emphasis was put on the B-17 as a coastal defense aircraft in the late 1930s, it proved a dismal failure in this role at Midway, where B-17s dropped 315 bombs on Japanese ships without scoring a single hit. On the other hand, the B-17 found an unexpected small role intercepting Japanese flying boats off Guadalcanal in the autumn of 1942, claiming two destroyed and one damaged. The B-17 had the advantages of greater speed and armament and comparable armor protection to the Mavis.

The B-17 remained in production until May 1945. The average cost of production dropped from $301,221 in 1939-1941 to $187,742 per unit when production ended.

Photo Gallery

B-17 preparing to land

U.S. Air Force

B-17 seen from above

U.S. Air Force

B-17 seen from below

U.S. Air Force

B-17 recognition manual page

U.S. Air Force

Close up of nose of B-17

U.S. Air Force

Cockpit of B-17

U.S. Air Force

Radio operator position of B-17

U.S. Air Force

Waist gunner positions of B-17

U.S. Air Force

Tailgunner position of B-17

U.S. Air Force

B-17 drops its bombs

U.S. Air Force

B-17D in flight

U.S. Air Force

B-17E in flight

U.S. Air Force


References

Bodie (1991)

Frank (1999)

Gamble (2010)
Gunston (1986)

Hess et al. (1998)

Jablonski (1965)

Johnson (2000)

Wilson (1998)



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