B-17 Flying Fortress
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| B-17 Flying Fortress | |
|---|---|
| Name | B-17 Flying Fortress |
| Caption | Boeing B-17G over Duxford |
| Role | Heavy bomber |
| Manufacturer | Boeing |
| First flight | 28 July 1935 |
| Introduced | 1938 |
| Retired | 1960s (USAF), later civilian |
| Primary user | United States Army Air Forces |
| Produced | 1936–1945 |
| Number built | 12,731 |
B-17 Flying Fortress The B-17 Flying Fortress was a four-engine heavy bomber developed by Boeing for the United States Army Air Corps and later fielded by the United States Army Air Forces during World War II. Renowned for ruggedness and defensive firepower, the type played central roles in strategic bombing campaigns over Nazi Germany, supporting operations linked to the Combined Bomber Offensive, the Eighth Air Force, and the Mediterranean Theater of Operations. Designed amid interwar aviation advances from firms such as Douglas Aircraft Company and Lockheed, the B-17 influenced postwar doctrine embraced by organizations including the United States Air Force and institutions like the National Air and Space Museum.
Design and Development
The B-17 emerged from a 1934 United States Army Air Corps request that led to Boeing proposals alongside competitors such as Consolidated Aircraft and Martin. Chief engineer Edgar Schmued and project teams at Boeing Field iterated on earlier monoplane designs influenced by the USS Akron era and transoceanic work by Pan American World Airways; prototypes like the Model 299 performed first flights at Kearney Field. Early design emphasized all-metal stressed-skin construction developed with suppliers including Pratt & Whitney for radial engines and aerodynamic research from the National Advisory Committee for Aeronautics. Continuous modification cycles produced successive blocks responding to operational feedback from units such as the 41st Bombardment Group and testing at Wright Field.
Operational History
Deployed before and during World War II, the B-17 was integral to daylight precision bombing doctrine advocated by figures like Haywood S. Hansell and organizations including the Eighth Air Force and Twelfth Air Force. Combat operations over Germany, Italy, and occupied France included participation in raids such as the Schweinfurt–Regensburg mission and the second raid on Berlin, often escorted by fighters fielded by P-51 Mustang units of the Fifth Air Force. Losses in early campaigns prompted tactics coordinated with commands like RAF Bomber Command and escorts from groups like the 356th Fighter Group. Postwar, surviving airframes served in roles with agencies such as the United States Geological Survey and civilian teams at events supported by the Experimental Aircraft Association.
Variants and Modifications
Production introduced numerous blocks—Model 299-derived B-17B through B-17G—each reflecting modifications from engineering offices at Boeing Wichita and maintenance depots like Tinker Air Force Base. Notable factory changes incorporated turrets supplied by firms such as Martin and radar suites developed by teams at MIT Radiation Laboratory. Field conversions produced reconnaissance versions used by Army Air Forces Photographic Units and electronic warfare adaptations tested in collaboration with Bell Telephone Laboratories and General Electric. Postwar modifications by civilian companies enabled cargo conversions for operators like Pan American and private collectors.
Armament and Defensive Systems
Defensive armament featured multiple machine-gun installations—nose, dorsal, ventral, waist, and tail turrets—manufactured by contractors including Bendix and Sperry Corporation and fired by gunners trained at bases like Lowry Field. Later blocks integrated the Sperry tail turret and the Emerson or Consolidated ball turret, while navigational and bombing systems incorporated Norden bombsights developed by engineers linked to Carl Norden and tested at Carlsbad Army Airfield. Electronic countermeasures and radar altimeters evolved with contributions from Raytheon and research units at Harvard University.
Production and Operators
Built primarily by Boeing with license production at plants operated by Douglas Aircraft Company, Lockheed Vega, and North American Aviation, total production exceeded 12,000 airframes assembled at facilities including Renton and Seattle Boeing Plant. Primary military operators were the United States Army Air Forces and later the United States Air Force, while international users and lend-lease recipients included units coordinated with Royal Air Force liaison offices and Allied squadrons attached to the Mediterranean Allied Air Forces. Postwar civil operators ranged from airline groups like Pan American World Airways to museums such as the National Museum of the United States Air Force.
Survivors and Preservation
Several B-17s survive worldwide in museums and airworthy collections maintained by organizations such as the Commemorative Air Force, the Experimental Aircraft Association, and the Imperial War Museum. Noteworthy surviving airframes are exhibited at the National Air and Space Museum, the American Air Museum in Britain, and at restoration facilities near Duxford and Evergreen Aviation & Space Museum. Preservation efforts often involve partnerships with heritage agencies like the Smithsonian Institution and veterans associations including the Veterans of Foreign Wars to maintain authenticity and flightworthiness for airshow participation.
Legacy and Cultural Impact
The B-17 symbolized American strategic airpower and entered popular culture through films like The Memphis Belle featured by studios such as Warner Bros. and documentaries produced by entities including the United States Army Air Forces Historical Division. Its operational stories are chronicled in works by historians associated with the Air Force Historical Research Agency and authors such as Ernie Pyle commentators, influencing memorials at sites like the National World War II Memorial and inspiring exhibitions at institutions like the Imperial War Museum Duxford. The aircraft shaped postwar aviation policy debates involving leaders from the Truman administration and informed design choices for successor bombers developed by firms like Boeing and Northrop Grumman.