View source for Engineering:Boeing B-17 Flying Fortress

{{Short description|American WWII-era heavy bomber}}
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<!-- This article is a part of Wikipedia:WikiProject Aircraft. Please see Wikipedia:WikiProject Aircraft/page content for recommended layout. -->
{|{{Infobox aircraft begin
 |name = B-17 Flying Fortress
 |image = File:B17 - Chino Airshow 2014 (framed).jpg
 |image_border = 
 |caption = A B-17G, ''Sentimental Journey'', performing at the 2014 Chino Airshow in Chino, California
}}{{Infobox aircraft type
 |type = [[Engineering:Heavy bomber|Heavy bomber]]
 |national origin = United States
 |manufacturer = [[Company:Boeing|Boeing]]
 |designer = 
 |first flight = 28 July 1935<ref name= "first flight" />
 |introduced = April 1938
 |retired = 1968 ({{wipe|Brazilian Air Force}})
 |status = Retired
 |primary user = {{wipe|United States Army Air Forces}}
 |more users = {{wipe|Royal Air Force}}
 |produced = 1936–1945
 |number built = 12,731<ref name= "Yenne.p8" /><ref>Angelucci and Matricardi 1988, p. 46.</ref>
 |developed from = 
 |variants with their own articles = {{plainlist|
* [[Engineering:Boeing XB-38 Flying Fortress|Boeing XB-38 Flying Fortress]]
* [[Engineering:Boeing YB-40 Flying Fortress|Boeing YB-40 Flying Fortress]]
* [[Engineering:Boeing C-108 Flying Fortress|Boeing C-108 Flying Fortress]]
}}
 |developed into = [[Engineering:Boeing 307 Stratoliner|Boeing 307 Stratoliner]]
}}
|}

The '''Boeing B-17 Flying Fortress''' is an American four-engined [[Engineering:Heavy bomber|heavy bomber]] developed in the 1930s for the United States Army Air Corps (USAAC). A fast and high-flying bomber of its era, the B-17 was used primarily in the European Theater of Operations and dropped more bombs than any other aircraft during [[Social:World War II|World War II]]. It is the [[Engineering:List of most-produced aircraft|third-most produced bomber]] of all time, behind the American four-engined [[Engineering:Consolidated B-24 Liberator|Consolidated B-24 Liberator]] and the German multirole, twin-engined [[Engineering:Junkers Ju 88|Junkers Ju 88]]. It was also employed as a transport, antisubmarine aircraft, drone controller, and search-and-rescue aircraft.

In a USAAC competition, [[Company:Boeing|Boeing's]] prototype Model 299/XB-17 outperformed two other entries but crashed, losing the initial 200-bomber contract to the [[Engineering:Douglas B-18 Bolo|Douglas B-18 Bolo]]. Still, the Air Corps ordered 13 more B-17s for further evaluation, which were introduced into service in 1938. The B-17 evolved through numerous design advances<ref>Parker 2013, pp. 35, 40–48.</ref><ref>Herman 2012, pp. 292–299, 305, 333.</ref> but from its inception, the USAAC (later, the USAAF) promoted the aircraft as a strategic weapon. It was a relatively fast, high-flying, long-range bomber with heavy defensive armament at the expense of bombload. It also developed a reputation for toughness based upon stories and photos of badly damaged B-17s safely returning to base.

The B-17 saw early action in the Pacific War, where it conducted raids against Japanese shipping and airfields.<ref>Parker 2013, p. 41.</ref> But it was primarily employed by the {{wipe|United States Army Air Forces}} in the daylight component of the Allied strategic bombing campaign over Europe, complementing RAF Bomber Command's night bombers in attacking German industrial, military and civilian targets.<ref name="Carey Pointblank" /> Of the roughly {{Nowrap|1.5 million tons}} of bombs dropped on [[Place:Nazi Germany|Nazi Germany]] and its occupied territories by Allied aircraft, over {{Nowrap|640 000 tons}} (42.6%) were dropped from B-17s.<ref name= "Yenne.p46" />

As of November 2022, four aircraft remain airworthy, none flown in combat. Dozens more are in storage or on static display, the oldest of which is ''The Swoose'', a B-17D which was flown in combat in the Pacific on the first day of the United States' involvement in World War II.

== Development ==

=== Origins ===
{{multiple image
| direction = vertical
| width     = 220
| image1    =Boeing XB-17 (Model 299).jpg
| caption1  = Model 299 ''NX13372''
| image2    =Boeing XB-17 (Model 299) nose turret with gun.jpg
| caption2  = [[Engineering:Gun turret#Aircraft|Gun turret]] atop the Model 299's nose glazing
| image3    =Boeing Model 299 crash.jpg
| caption3  = Crashed Model 299
| image4    =Boeing Y1B-17 in flight.jpg
| caption4  = Boeing Y1B-17 in flight
<!-- Please do not add more images here as it disrupts the spacing -->
}}
On 8 August 1934, the USAAC tendered a proposal for a multiengine bomber to replace the [[Engineering:Martin B-10|Martin B-10]]. The Air Corps was looking for a bomber capable of reinforcing the air forces in Hawaii, Panama, and Alaska.<ref name="Tate.p164" /> Requirements were for it to carry a "useful bombload" at an altitude of {{convert|10000|ft|m|abbr=on}} for 10 hours with a top speed of at least {{convert|200|mph|km/h|abbr=on}}.<ref name="Swan Mil p74" />

They also desired, but did not require, a bomber with a range of {{convert|2000|mi|km|-2|abbr=on}} and a speed of {{convert|250|mph|km/h|abbr=on}}. The competition for the air corps contract was to be decided by a "fly-off" between Boeing's design, the [[Engineering:Douglas B-18 Bolo|Douglas DB-1]], and the Martin Model 146 at Wilbur Wright Field in Dayton, Ohio.

The prototype B-17, with the Boeing factory designation of Model 299, was designed by a team of engineers led by E. Gifford Emery and Edward Curtis Wells, and was built at Boeing's own expense.<ref name="WoF p41" /> It combined features of the company's experimental [[Engineering:Boeing XB-15|XB-15]] bomber and [[Engineering:Boeing 247|247]] transport.<ref name="Swan Mil p74" /> The B-17's armament consisted of five .30 caliber (7.62&nbsp;mm) [[Engineering:Machine gun|machine gun]]s, with a payload up to {{convert|4800|lb|kg|abbr=on}} of bombs on two racks in the bomb bay behind the cockpit. The aircraft was powered by four Pratt & Whitney R-1690 Hornet radial engines, each producing {{convert|750|hp|kW|-2|abbr=on}} at {{convert|7000|ft|m|-2|abbr=on}}.<ref name="Bowers Boeing p291-2" />

The first flight of the Model 299 was on {{Nowrap|28 July}} 1935 with Boeing chief test pilot Leslie Tower at the controls.<ref name="first flight" /><ref name="Sal.p46" /> The day before, Richard Williams, a reporter for ''The Seattle Times'', coined the name "Flying Fortress" when – observing the large number of machine guns sticking out from the new aircraft – he described it as a "15-ton flying fortress" in a picture caption.<ref>Freeman 1993, p. 8.</ref> The most distinctive mount was in the nose, which allowed the single machine gun to be fired toward nearly all frontal angles.<ref>[https://books.google.com/books?id=WSgDAAAAMBAJ&pg=PA24 "Army's Biggest Bomber Has Rotating Nose"]. ''Popular Science Monthly'', August 1937.</ref>

Boeing was quick to see the value of the name and had it trademarked for use.{{NoteTag |1 = The ''Air Corps News Letter'', however, notes in its edition of 1 January 1938 ([http://newpreview.afnews.af.mil/shared/media/document/AFD-110421-039.pdf ACNL Vol. XXI, No. 1, p. 7] {{webarchive|url=https://web.archive.org/web/20150903213218/http://newpreview.afnews.af.mil/shared/media/document/AFD-110421-039.pdf |date=3 September 2015 }}) an attempt by the Langley Field correspondent to apply the appellation "Jeep" to the B-17, which it objected to as "not befitting" the aircraft and adding, "Why not let the term 'Flying Fortress' suffice?"}} Boeing also claimed in some of the early press releases that Model 299 was the first combat aircraft that could continue its mission if one of its four engines failed.<ref>[https://books.google.com/books?id=wN8DAAAAMBAJ&pg=PA519 "Giant Bomber Flies Four Miles Per Minute"]. ''Popular Mechanics'', October 1935.</ref> On {{Nowrap|20 August 1935}}, the prototype flew from Seattle to Wright Field in nine hours and three minutes with an average cruising speed of {{convert|252|mph|km/h}}, much faster than the competition.<ref name="NYTimes.299Record" />

At the fly-off, the four-engined Boeing's performance was superior to those of the twin-engine DB-1 and Model 146. In March 1935 Army Chief of Staff General Douglas MacArthur created GHQ Air Force and promoted lieutenant colonel Frank Maxwell Andrews to brigadier general to become the head of GHQ Air Force. MacArthur and Andrews both believed that the capabilities of large four-engined aircraft exceeded those of shorter-ranged, twin-engine aircraft, and that the B-17 was better suited to new, emerging USAAC doctrine.<ref name="Zamzow.33" /><ref>{{cite web|url=https://media.defense.gov/2016/Mar/14/2001480192/-1/-1/0/0908GHQ.PDF|title=GHQ Air Force: This strange arrangement in 1935 split the Air Corps into two camps—but it led the way to an independent Air Force Page 64-66|work=Air Force Magazine|date=September 2008|access-date=January 3, 2024}}</ref> Their opinions were shared by the air corps procurement officers, and even before the competition had finished, they suggested buying 65 B-17s.<ref name="Tate 165" /><ref name="Zamzow.34" />

On 30 October 1935, a test flight determining the rate of climb and service ceiling was planned. The command pilot was Major Ployer Peter Hill, Wright Field Material Division Chief of the Flying Branch, his first flight in the Model 299. Copilot was Lieutenant Donald Putt, while Boeing chief test pilot Leslie R. Tower was behind the pilots in an advisory role. Also on board were Wright Field test observer John Cutting and mechanic Mark Koegler. Tragically, the plane stalled and spun into the ground soon after takeoff, bursting into flames. Though initially surviving the impact, Hill died within a few hours, and Tower on 19 November. Post-accident interviews with Tower and Putt determined the control surface gust lock had not been released.<ref name="Museum"/> Doyle notes, "The loss of Hill and Tower, and the Model 299, was directly responsible for the creation of the modern written [[Medicine:Checklist|checklist]] used by pilots to this day."<ref>{{cite book |last1=Doyle |first1=David |title=B-17 Flying Fortress, Vol. 1: Boeing's Model 299 through B-17D in World War II |date=2020 |publisher=Schiffer Publishing, Ltd. |location=Atglen |isbn=9780764359552 |pages=6–7}}</ref><ref name="Checks"/>

The crashed Model 299 could not finish the evaluation, thus disqualifying it from the competition.<ref name="Zamzow.34" /> While the Air Corps was still enthusiastic about the aircraft's potential, Army officials were daunted by its cost;<ref name="Sal.p48" /> Douglas quoted a unit price of $58,200 ({{inflation|US-GDP|58200|1935|r=-3|fmt=eq}}) based on a production order of 220 aircraft, compared with $99,620 ({{inflation|US-GDP|99620|1935|r=-3|fmt=eq}} ) from Boeing.<ref name="Francillon Doug p201-2" /> MacArthur's successor, Army Chief of Staff Malin Craig, canceled the order for 65 YB-17s and ordered 133 of the twin-engined Douglas B-18 Bolo, instead. Secretary of War Harry Hines Woodring in October 1938 decided that no four-engine bombers, including B-17s, would be purchased by the War Department in 1939. <ref name="Tate 165" /><ref name="Zamzow.34" /><ref>{{cite web|url= https://www.airandspaceforces.com/article/rise-of-the-air-corps|title=Rise of the Air Corps|work=Air & Space Forces Magazine|date=May 12, 2022|access-date=January 3, 2024}}</ref>
{{blockquote|The loss was not total... But Boeing's hopes for a substantial bomber contract were dashed.|Peter Bowers, 1976<ref name="Bowers1976.p37">Bowers 1976, p. 37.</ref>}}

=== Initial orders ===
[[File:B17F - Woman workers at the Douglas Aircraft Company plant, Long Beach, Calif.jpg|thumb|Installation of fixtures and assemblies on a tail fuselage section of a B-17 at the Douglas plant in Long Beach, California, October 1942]]
[[File:B-17B Bombers at March Field, California prior to 7 December 1941.jpg|thumb|B-17Bs at March Field, California, prior to attack on Pearl Harbor, with framed nose glazing of the style retained through the B-17E model]]
[[File:B-17 at Mighty 8th Air Force Museum, Pooler, GA, US.jpg|thumb|Nose of a B-17G being restored at the Mighty Eighth Air Force Museum ]]

Despite the crash, the USAAC had been impressed by the prototype's performance, and on {{Nowrap|17 January}} 1936, through a legal loophole,<ref name="Erickson"/><ref name="Meilinger" /> the Air Corps ordered 13 YB-17s (designated Y1B-17 after November 1936 to denote its special F-1 funding) for service testing.<ref name="Zamzow.34" /> The YB-17 incorporated a number of significant changes from the Model 299, including more powerful Wright R-1820-39 Cyclone engines. Although the prototype was company-owned and never received a military serial (the B-17 designation itself did not appear officially until January 1936, nearly three months after the prototype crashed),<ref name="Bowers1976.p12" /> the term "XB-17" was retroactively applied to the ''NX13372's'' airframe and has entered the lexicon to describe the first Flying Fortress.

Between 1 March and 4 August 1937, 12 of the 13 Y1B-17s were delivered to the 2nd Bombardment Group at Langley Field in Virginia for operational development and flight tests.<ref name="Swan Mil p75" /> One suggestion adopted was the use of a preflight checklist to avoid accidents such as that which befell the Model 299.<ref name="Meilinger" /><ref name="Checks2" />{{NoteTag|The idea of a pilot's checklist spread to other crew members, other air corps aircraft types, and eventually throughout the aviation world. ''Life'' published the lengthy B-17 checklist in its 24 August 1942 issue.<ref>[https://books.google.com/books?id=fk4EAAAAMBAJ&pg=PA65 "B-17 checklist"]. ''Life'', 24 August 1942.</ref>}} In one of their first missions, three B-17s, directed by lead navigator Lieutenant Curtis LeMay, were sent by General Andrews to "intercept" and photograph the Italian ocean liner ''Rex'' {{convert|610|mi|km}} off the Atlantic coast.<ref name="Zamzow.47" /> The mission was successful and widely publicized.<ref name="Maurer" /><ref name="USAF Rex" /> The 13th Y1B-17 was delivered to the Material Division at Wright Field, Ohio, to be used for flight testing.<ref name="Y1B-17" />

A 14th Y1B-17 (''37-369''), originally constructed for ground testing of the airframe's strength, was upgraded by Boeing with exhaust-driven General Electric turbo-superchargers, and designated Y1B-17A. Designed by Sanford Moss, engine exhaust gases turned the turbine's steel-alloy blades, forcing high-pressure ram air into the Wright Cyclone GR-1820-39 engine supercharger.<ref>{{cite web |url = https://aviationshoppe.com/manuals/wwii_aircraft_superchargers/wwii_aircraft_turbosupercharger.html |title = World War II – General Electric Turbosupercharges |website = aviationshoppe.com |access-date = 8 June 2017 |archive-date = 8 October 2019 |archive-url = https://web.archive.org/web/20191008054906/https://aviationshoppe.com/manuals/wwii_aircraft_superchargers/wwii_aircraft_turbosupercharger.html |url-status = dead }}</ref> Scheduled to fly in 1937, it encountered problems with the turbochargers, and its first flight was delayed until {{Nowrap|29 April}} 1938.<ref name="Donald" /> The aircraft was delivered to the Army on {{Nowrap|31 January}} 1939.<ref name="Bowers Boeing p293-4" /> Once service testing was complete, the Y1B-17s and Y1B-17A were redesignated B-17 and B-17A, respectively, to signify the change to operational status.<ref name="Wixley p23" />  The Y1B-17A had a maximum speed of {{convert|311|mph|kph}}, at its best operational altitude, compared to {{convert|239|mph|kph}} for the Y1B-17. Also, the Y1B-17A's new service ceiling was more than {{convert|2|miles|km}} higher at {{convert|38000|ft|m}}, compared to the Y1B-17's {{convert|27800|ft|m}}. These turbo-superchargers were incorporated into the B-17B.<ref>{{cite book |last1=Caidin |first1=Martin |title=Flying Forts: The B-17 in World War II |date=1968 |publisher=Bantam Books |location=New York |isbn=9780553287806 |pages=80, 95–99}}</ref>

Opposition to the Air Corps' ambitions for the acquisition of more B-17s faded, and in late 1937, 10 more aircraft designated B-17B were ordered to equip two bombardment groups, one on each U.S. coast.<ref name="B-17B" /> Improved with larger flaps and rudder and a well-framed, 10 panel plexiglass nose, the B-17Bs were delivered in five small batches between July 1939 and March 1940. In July 1940, an order for 512 B-17s was issued,<ref name="Pop1" /> but at the time of the attack on Pearl Harbor, fewer than 200 were in service with the army.<ref name="Meilinger" />

A total of 155 B-17s of all variants were delivered between {{nowrap|11 January}} 1937 and {{nowrap|30 November}} 1941, but production quickly accelerated, with the B-17 once holding the record for the highest production rate for any large aircraft.<ref name="Serling.p55" />{{NoteTag|Quote: "At the peak of production, Boeing was rolling out as many as 363 B-17s a month, averaging between 14 and 16 Forts a day, the most incredible production rate for large aircraft in aviation history." This production rate was, however, surpassed by that of the [[Engineering:Consolidated B-24 Liberator|Consolidated B-24 Liberator]].}} The aircraft went on to serve in every World War&nbsp;II combat zone, and by the time production ended in May 1945, 12,731 B-17s had been built by Boeing, [[Company:Douglas Aircraft Company|Douglas]], and [[Company:Vega Aircraft Corporation|Vega]] (a subsidiary of [[Company:Lockheed Corporation|Lockheed]]).<ref name="Yenne.p6" /><ref>Herman, Arthur. ''Freedom's Forge: How American Business Produced Victory in World War II'', pp. 292–99, 305, Random House, New York, 2012. {{ISBN|978-1-4000-6964-4}}.</ref><ref>Parker 2013, pp. 35, 40–48, 59, 74.</ref><ref>Borth 1945, pp. 70–71, 83, 92, 256, 268–69.</ref>
{{blockquote|Though the crash of the prototype 299 in 1935 had almost wiped out Boeing, now it was seen as a boon. Instead of building models based on experimental engineering, Boeing had been hard at work developing their bomber and now had versions ready for production far better than would have been possible otherwise. One of the most significant weapons of World War II would be ready, but only by a hair.|Jeff Ethell, 1985<ref name="Pop1" />}}

== Design and variants ==
{{Main|Engineering:List of Boeing B-17 Flying Fortress variants}}

[[File:Boeing XB-17 blister turret.jpg|thumb|Waist position gun blister of Model 299, not adopted for production]]

{| class="wikitable floatright" style="text-align:center; width:30em" 
|+ Production numbers
! Variant
! Produced
! First flight
|-
| Model 299 || style="text-align:right;| 1 || 28 July 1935<ref name="first flight" />
|- style="background:#f5faff;"
| YB-17 || style="text-align:right;| 13 || 2 December 1936<ref name="Bowers Boeing p292" />
|-
| YB-17A || style="text-align:right;| 1 || 29 April 1938<ref name="Donald" />
|- style="background:#f5faff;"
| B-17B || style="text-align:right;| 39 || 27 June 1939<ref name="Bowers boeing p294" />
|-
| B-17C || style="text-align:right;| 38 || 21 July 1940<ref name="Bowers Boeing p295" />
|- style="background:#f5faff;"
| B-17D || style="text-align:right;| 42 || 3 February 1941<ref name="Swan Mil p76" />
|-
| B-17E || style="text-align:right;| 512 || 5 September 1941<ref name="Bowers Boeing p297" />
|- style="background:#f5faff;"
| B-17F (total) || style="text-align:right;| '''3,405''' || 30 May 1942<ref name="Bowers Boeing p299" /><ref name="Swan Mil p78" />
|-
| B-17F-BO || style="text-align:right;| 2,300 || <ref name="Bowers Boeing p299" />
|- style="background:#f5faff;"
| B-17F-DL || style="text-align:right;| 605 || <ref name="Bowers Boeing p299" />
|-
| B-17F-VE || style="text-align:right;| 500 || <ref name="Bowers Boeing p299" />
|- style="background:#f5faff;"
| B-17G (total) || style="text-align:right;| '''8,680''' || 16 August 1943 <!--- what is this?---<Osborne, Story, page 98/>---->
|-
| B-17G-BO || style="text-align:right;| 4,035 ||
|- style="background:#f5faff;"||
| B-17G-DL || style="text-align:right;| 2,395 ||
|-
| B-17G-VE || style="text-align:right;| 2,250 ||
|- style="background:#f5faff;"
| Total || style="text-align:right;| '''12,731''' ||
|-
| colspan="3" style="text-align:left;" font-size: 70%| B-17s were built at Boeing Plant 2, Seattle, Washington (BO), Lockheed-Vega, Burbank, California (VE) and Douglas Aircraft, Long Beach, California (DL)<ref>Yenne, Bill, ''B-17 at War'': p. 16; Zenith Press; 2006: {{ISBN|978-0760325223}}</ref>
|}

The aircraft went through several alterations in each of its design stages and variants. Of the 13 YB-17s ordered for service testing, 12 were used by the 2nd Bomb Group at Langley Field, Virginia, to develop heavy bombing techniques, and the 13th was used for flight testing at the Material Division at Wright Field, Ohio.<ref name="Y1B-17" /> Experiments on this aircraft led to the use of a quartet of General Electric turbo-superchargers, which later became standard on the B-17 line. A 14th aircraft, the YB-17A, originally destined for ground testing only and upgraded with the turbochargers,<ref name="flightinter" /> was redesignated B-17A after testing had finished.<ref name="Bowers Boeing p293-4" /><ref name="Wixley p23" />

As the production line developed, Boeing engineers continued to improve upon the basic design. To enhance performance at slower speeds, the B-17B was altered to include larger [[Engineering:Rudder|rudder]]s and flaps.<ref name="Bowers boeing p294" /> The B-17C changed from three bulged, oval-shaped gun blisters to two flush, oval-shaped gun window openings, and on the lower fuselage, a single "bathtub" gun gondola housing,<ref name="Bowers Boeing p295" /> which resembled the similarly configured and located ''Bodenlafette''/"Bola" ventral defensive emplacement on the German [[Engineering:Heinkel He 111|Heinkel He 111]]P-series medium bomber.

While models A through D of the B-17 were designed defensively, the large-tailed B-17E was the first model primarily focused on offensive warfare.<ref name="flightinter" /> The B-17E was an extensive revision of the Model 299 design: The fuselage was extended by {{convert|10|ft|m|abbr=on}}; a much larger rear fuselage, vertical tailfin, rudder, and horizontal stabilizer were added; [[Social:Tail gunner|a gunner's position was added in the new tail]];{{NoteTag| During the crash investigation of [[Engineering:Boeing 307 Stratoliner#Operational history|Boeing 307 Stratoliner NX19901]], it was found that two B-17s had already spun from lack of directional stability. British combat experience with the B-17 was also showing the need for a tail gunner. Boeing was not willing to add a turret because they did not want to disrupt the clean aerodynamics. The inadequate directional stability exposed by two spin incidents and a crash, brought about a redesigned vertical stabilizer and dorsal fin. A compromise for the tail turret resulted in handheld tail guns. The combination created a successful design. Not only were defensive needs solved, but the improved lateral stability made precision high altitude bombing possible.<ref>{{cite web |url=https://www.thisdayinaviation.com/tag/boeing-model-307-stratoliner/ |title=Boeing Model 307 Stratoliner |website=Archives – This Day in Aviation |access-date=2021-06-19}}</ref><ref>{{cite web |url=http://www.b17queenofthesky.com/variants/prototype.php?id=10&tle=B-17E |website=B-17 Queen of the Sky |title=B-17E page |access-date=2021-06-19 |archive-date=21 June 2021 |archive-url=https://web.archive.org/web/20210621212650/http://b17queenofthesky.com/variants/prototype.php?id=10&tle=B-17E |url-status=dead }}</ref>}} the nose (especially the bombardier's framed, 10-panel nose glazing) remained relatively the same as the earlier B through D versions had; a [[Company:Sperry Corporation|Sperry]] electrically powered manned dorsal [[Engineering:Aircraft gun turret|gun turret]] just behind the cockpit was added; a similarly powered (also built by Sperry) manned ventral ball turret just aft of the bomb bay – replaced the relatively hard-to-use, Sperry model 645705-D<ref>B-17 Erection and Maintenance Manual 01-20EE-2</ref> remotely operated ventral turret on the earliest examples of the E variant. These modifications resulted in a 20% increase in aircraft weight.<ref name="flightinter" /> The B-17's turbocharged Wright R-1820 Cyclone 9 engines were upgraded to increasingly more powerful versions of the same powerplants throughout its production, and similarly, the number of machine gun emplacement locations was increased.<ref name="WoF p56-7" />

[[File:An Army sentry guards new B-17 F (Flying Fortress) bombers at the airfield of Boeing's Seattle plant. The ship will... - NARA - 196372.jpg|thumb|left|Boeing-built B-17Fs, with the clear-view two-piece Plexiglas bombardier's nose.]]
The B-17F variant was the primary version used the Eighth Air Force to face the Germans in 1943, and standardized the manned Sperry ball turret for ventral defense, also replacing the earlier, 10-panel framed bombardier's nose glazing from the B subtype with an enlarged, nearly frameless Plexiglas bombardier's nose enclosure for improved forward vision.

Two experimental versions of the B-17 were flown under different designations, the XB-38 'Flying Fortress' and the YB-40 'Flying Fortress.' The XB-38 was an engine testbed for Allison V-1710 liquid-cooled engines, should the Wright engines normally used on the B-17 become unavailable. The only prototype XB-38 to fly crashed on its ninth flight, and the concept was abandoned. The Allison V-1710 was reallocated to fighter aircraft.<ref name="Francillon Lock p213-5" /><ref name="WoF p66" />

The [[Engineering:Boeing YB-40 Flying Fortress|YB-40]] was a heavily armed modification of the standard B-17 used before the [[Engineering:North American P-51 Mustang|North American P-51 Mustang]], an effective long-range fighter, became available to act as escort. Additional armament included an additional dorsal turret in the radio room, a remotely operated and fired Bendix-built "chin turret" directly below the bombardier's accommodation, and twin 50 caliber (12.7 mm) guns in each of the waist positions. The ammunition load was over 11,000 rounds. All of these modifications made the YB-40 well over {{convert|10000|lb|abbr=on}} heavier than a fully loaded B-17F. The YB-40s with their greater weight, had trouble keeping up with the lighter bombers once they had dropped their bombs, so the project was abandoned and finally phased out in July 1943.<ref name="WoF 62-3,5" /><ref name="Francillon Lock p212" /><ref name="Bowers Boeing p307-8" /> The final production blocks of the B-17F from Douglas' plants did, however, adopt the YB-40's "chin turret", giving them a much-improved forward defense capability.<ref>{{cite web |url=http://www.b17queenofthesky.com/variants/prototype.php?id=12&tle=B-17F |title=B17 – Queen of the Sky – The B-17F |last=Lyman |first=Troy |date=12 May 2003 |website=Troy Lyman's B-17 Flying Fortress Site |access-date=24 June 2014 |archive-date=9 August 2014 |archive-url=https://web.archive.org/web/20140809192902/http://b17queenofthesky.com/variants/prototype.php?id=12&tle=B-17F |url-status=dead }}</ref>
[[File:B-17G Nose in Detail.jpg|upright|thumb|left|B-17G nose detail]]

By the time the definitive B-17G appeared, the number of guns had been increased from seven to 13, the designs of the gun stations were finalized, and other adjustments were completed. The B-17G was the final version of the Flying Fortress, incorporating all changes made to its predecessor, the B-17F,<ref name="flightinter" /> and in total, 8,680 were built,<ref name="WoF p63-4" /> the last (by Lockheed) on {{Nowrap|28 July}} 1945.<ref name="Francillon Lock p211" /> Many B-17Gs were converted for other missions such as cargo hauling, engine testing, and reconnaissance.<ref name="Bowers Boeing p286-7" /> Initially designated SB-17G, a number of B-17Gs were also converted for search-and-rescue duties, later to be redesignated B-17H.<ref name="Bowers Boeing p303-4" />

[[File:Boeing SB-17G.jpg|thumb|Postwar SB-17G-95DL (ser. no. ''44-83722''), assigned to the 2nd ERS as a search-and-rescue aircraft, beside a Stinson L-5]]

Late in World War&nbsp;II, at least 25 B-17s were fitted with radio controls and television cameras, loaded with {{convert|20000|lb|abbr=on}} of high explosives and designated BQ-7 "Aphrodite missiles" for Operation Aphrodite against bombing-resistant German bunkers. The operation, which involved remotely flying the Aphrodite drones onto their targets by accompanying CQ-17 "mothership" control aircraft, was approved on {{nowrap|26 June}} 1944, and assigned to the 388th Bombardment Group stationed at RAF Fersfield, a satellite of RAF Knettishall.<ref name="Ramsey" />

The first four drones were sent to Mimoyecques (V-3 site), the Siracourt V-1 bunker, and the V-2 Blockhaus d'Éperlecques at Watten, and La Coupole at Wizernes on 4 August, causing little damage and two pilots were killed. On August 12,  a [[Engineering:Consolidated B-24 Liberator|Consolidated B-24 Liberator]], part of the United States Navy's contribution ("Project Anvil"), en route for [[Finance:Heligoland|Heligoland]] piloted by Lieutenant Joseph P. Kennedy Jr. (future U.S. president [[Biography:John F. Kennedy|John F. Kennedy]]'s elder brother) exploded over the Blyth estuary. Blast damage was caused over a radius of {{convert|5|mi}}. Naval flights stopped but a few more missions were flown by the USAAF. The Aphrodite project was effectively scrapped in early 1945.<ref name="Ramsey">Ramsey, Winston G. "The V-Weapons". London: ''After the Battle'', Number 6, 1974, pp. 20–21.</ref>

== Operational history ==
[[File:B-17E 19 BG.jpg|thumb|Boeing B-17E Flying Fortress of the 19th Bombardment Group USAAF, summer 1942]]
[[File:Living Legends.jpg|thumb|B-17 Flying Fortresses from the 398th Bombardment Group flying a bombing mission to Neumünster, Germany, on 13 April 1945.]]

The B-17 began operations in World War&nbsp;II with the {{wipe|Royal Air Force}} (RAF) in 1941, and in the Southwest Pacific with the U.S. Army. The 19th Bombardment Group had deployed to Clark Field in the Philippines a few weeks before the Japanese attack on Pearl Harbor as the first of a planned heavy bomber buildup in the Pacific. Half of the group's B-17s were wiped out on 8 December 1941 when they were caught on the ground during refueling and rearming for a planned attack on Japanese airfields on Formosa. The small force of B-17s operated against the Japanese invasion force until they were withdrawn to Darwin, in Australia's Northern Territory. In early 1942, the 7th Bombardment Group began arriving in Java with a mixed force of B-17s and LB-30/B-24s.<ref name="Edmonds">Edmonds, Walter. ''They Fought With They Had''. 1951, pp. 1–314.{{page needed|date=May 2015}}</ref> A squadron of B-17s from this force detached to the Middle East to join the First Provisional Bombardment Group, thus becoming the first American B-17 squadron to go to war against the Germans.{{citation needed|date=May 2015}} After the defeat in Java, the 19th withdrew to Australia, where it continued in combat until it was sent home by General George C. Kenney when he arrived in Australia in mid-1942.<ref>Kenney, George C. ''General Kenney Reports''. New York: Duell, Sloan and Pierce, 1949.</ref> In July 1942, the first USAAF B-17s were sent to England to join the Eighth Air Force. Later that year, two groups moved to Algeria to join Twelfth Air Force for operations in North Africa. The B-17s were primarily involved in the daylight precision strategic bombing campaign against German targets ranging from U-boat pens, docks, warehouses, and airfields to industrial targets such as aircraft factories.<ref name="Cravens, Wesley 1956">Cravens, Wesley ''Army Air Forces in WW II''. Washington, D.C.: Office of Air Force History, 1956.</ref> In the campaign against German aircraft forces in preparation for the invasion of France, B-17 and B-24 raids were directed against German aircraft production while their presence drew the Luftwaffe fighters into battle with Allied fighters.<ref name="Carey Pointblank" />

During World War II, the B-17 equipped 32 overseas combat groups, inventory peaking in August 1944 at 4,574 USAAF aircraft worldwide.<ref name="Baugher Squads" /> The British heavy bombers, the [[Engineering:Avro Lancaster|Avro Lancaster]] and [[Engineering:Handley Page Halifax|Handley Page Halifax]], dropped 608,612 long tons (681,645 short tons) and 224,207 long tons (251,112 short tons)<ref>{{cite web|url=http://www.raf.mod.uk/rafbramptonwytonhenlow/aboutus/handleypagehalifax.cfm|title=Handley Page Halifax|archive-url=https://web.archive.org/web/20080530210057/http://www.raf.mod.uk/rafbramptonwytonhenlow/aboutus/handleypagehalifax.cfm|archive-date=30 May 2008|website=RAF.mod.uk|access-date=4 October 2019}}</ref> respectively.

=== RAF use ===
[[File:B-17C with RAF colors.jpg|thumb|RAF Fortress I serial ''AN529'', with He 111H-style "bathtub" ventral gondola]]
The RAF entered World War II with no heavy bomber of its own in service; the biggest available were long-range medium bombers such as the [[Engineering:Vickers Wellington|Vickers Wellington]], which could carry up to {{convert|4500|lb|kg}} of bombs.<ref name="Andrews & Morgan p340" /> While the [[Engineering:Short Stirling|Short Stirling]] and [[Engineering:Handley Page Halifax|Handley Page Halifax]] became its primary bombers by 1941, in early 1940, the RAF agreed with the U.S. Army Air Corps to acquire 20 B-17Cs, which were given the service name Fortress I. Their first operation, against Wilhelmshaven on {{Nowrap|8 July}} 1941 was unsuccessful.<ref name="Yenne.p23" /><ref name="Chant" /> On {{Nowrap|24 July}} three B-17s of 90 Squadron took part in a raid on the German capital ship Gneisenau and Prinz Eugen anchored in Brest from {{convert|30,000|ft|m|abbr=on}}, to draw German fighters away from 18 [[Engineering:Handley Page Hampden|Handley Page Hampden]]s attacking at lower altitudes, and in time for 79 Vickers Wellingtons to attack later with the German fighters refueling. The operation did not work as expected, with 90 Squadron's Fortresses being unopposed.<ref name="Chorlton p38">Chorlton ''Aeroplane'' January 2013, p. 38.</ref><ref name="hardest p122-3">Richards 1995, pp. 122–23.</ref>{{sfn|Garzke|Dulin|pp=159–60}}

By September, the RAF had lost eight B-17Cs in combat and had experienced numerous mechanical problems, and Bomber Command abandoned daylight bombing raids using the Fortress I because of the aircraft's poor performance. The experience showed both the RAF and USAAF that the B-17C was not ready for combat, and that improved defenses, larger bomb loads, and more accurate bombing methods were required. However, the USAAF continued using the B-17 as a day bomber, despite misgivings by the RAF that attempts at daylight bombing would be ineffective.<ref name="Weigley.338" />

As use by Bomber Command had been curtailed, the RAF transferred its remaining Fortress&nbsp;I aircraft to Coastal Command for use as a long-range maritime patrol aircraft.<ref name="Stitt 1" /> These were augmented starting in July 1942 by 45 Fortress Mk IIA (B-17E) followed by 19 Fortress Mk II (B-17F) and three Fortress Mk III (B-17G). A Fortress IIA from No. 206 Squadron RAF sank U-627 on {{Nowrap|27 October}} 1942, the first of 11 U-boat kills credited to RAF Fortress bombers during the war.<ref name="Wynn.93" />

As sufficient Consolidated Liberators finally became available, Coastal Command withdrew the Fortress from the Azores, transferring the type to the meteorological reconnaissance role. Three squadrons undertook Met profiles from airfields in Iceland, Scotland, and England, gathering data for vital weather forecasting purposes.

The RAF's No. 223 Squadron, as part of [[Organization:No. 100 Group RAF|100 Group]], operated several Fortresses equipped with an electronic warfare system known as "Airborne Cigar" (ABC). This was operated by German-speaking radio operators to identify and jam German ground controllers' broadcasts to their nightfighters. They could also pose as ground controllers themselves to steer nightfighters away from the bomber streams.<ref>{{cite news|url=https://www.telegraph.co.uk/news/main.jhtml?view=DETAILS&grid=&xml=/news/2007/12/13/db1301.xml|archive-url=https://web.archive.org/web/20071214211240/http://www.telegraph.co.uk/news/main.jhtml?view=DETAILS&grid=&xml=%2Fnews%2F2007%2F12%2F13%2Fdb1301.xml|url-status=dead|archive-date=14 December 2007|title=Obituaries: John Hereford|newspaper=The Daily Telegraph|date=13 December 2007|access-date=8 July 2021}}</ref>

=== Initial USAAF operations over Europe ===
[[File:Marks and letters on the tails of B-17 during WWII in Europe.jpg|thumb|Marks and letters on the tails of B-17 during WWII in Europe]]

The air corps – renamed {{wipe|United States Army Air Forces}} (USAAF) on 20 June 1941 – used the B-17 and other bombers to bomb from high altitudes with the aid of the then-secret [[Norden bombsight]], known as the "Blue Ox",<ref>{{cite news |url=https://www.nps.gov/articles/second-generation-norden-bombsight-vault.htm |title=Second-Generation Norden Bombsight Vault |work=National Park Service |access-date=2 July 2017}}</ref><ref>"Blue Ox." ''National Geographic Magazine'', Vol. LXXXIII, Number One, January 1943, p. 7, Ad(i).</ref> which was an optical electromechanical gyrostabilized [[Analog computer|analog computer]].<ref>Peterson, Paul. ''Ludington Daily News'', 16 April 1994, p. 1.</ref> The device was able to determine, from variables put in by the bombardier, the point at which the aircraft's bombs should be released to hit the target. The bombardier essentially took over flight control of the aircraft during the bomb run, maintaining a level altitude during the final moments before release.<ref name="Baugher B-17B" />

The USAAF began building up its air forces in Europe using B-17Es soon after entering the war. The first Eighth Air Force units arrived in High Wycombe, England, on {{Nowrap|12 May}} 1942, to form the 97th Bomb Group.<ref name="Northstar" /> On {{Nowrap|17 August}} 1942, 12 B-17Es of the 97th, with the lead aircraft piloted by Major Paul Tibbets and carrying Brigadier General Ira Eaker as an observer, were close escorted by four squadrons of RAF [[Engineering:Supermarine Spitfire|Spitfire IXs]] (and a further five squadrons of Spitfire Vs to cover the withdrawal) on the first USAAF heavy bomber raid over Europe, against the large railroad marshalling yards at Rouen-Sotteville in France, while a further six aircraft flew a diversionary raid along the French coast.<ref name="WoF p59-0" /><ref name="AAF combat" /> The operation, carried out in good visibility, was a success, with only minor damage to one aircraft, unrelated to enemy action, and half the bombs landing in the target area.<ref>{{citation |chapter-url=http://www.ibiblio.org/hyperwar/AAF/I/AAF-I-18.html |chapter=Chapter 18: Rouen-Sotteville, No. 1, 17 August 1942 |volume=I: Plans & Early Operations, January 1939 to August 1942 |pages=662–63 |author1=Arthur B. Gerguson |editor=Craven W |editor2=Cate, J |title=The Army Air Forces in WWII}}</ref> The raid helped allay British doubts about the capabilities of American heavy bombers in operations over Europe.{{citation needed|date=October 2017}}

Two additional groups arrived in Britain at the same time, bringing with them the first B-17Fs, which served as the primary AAF heavy bomber fighting the Germans until September 1943. As the raids of the American bombing campaign grew in numbers and frequency, German interception efforts grew in strength (such as during the attempted bombing of Kiel on 13 June 1943<ref name="Bowman.7" />), such that unescorted bombing missions came to be discouraged.<ref name="Weigley 339" />

=== Combined offensive ===
The two different strategies of the American and British bomber commands were organized at the Casablanca Conference in January 1943. The resulting "Combined Bomber Offensive" weakened the Wehrmacht, destroyed German morale, and established air superiority through Operation Pointblank's destruction of German fighter strength in preparation for a ground offensive.<ref name="Carey Pointblank" /> The USAAF bombers attacked by day, with British operations – chiefly against industrial cities – by night.<ref>{{Cite web|last=November 1998|first=Brian Todd Carey|date=2006-06-12|title=How Allied Air Attacks Evolved During World War II|url=https://www.historynet.com/how-allied-air-attacks-evolved-during-world-war-ii.htm|access-date=2021-03-24|website=HistoryNet|language=en-US}}</ref>

[[File:B-17F formation over Schweinfurt, Germany, August 17, 1943.jpg|left|thumb|B-17F formation over Schweinfurt, Germany, {{Nowrap|17 August}} 1943]]
[[File:B-17F Radar Bombing over Germany 1943.jpg|left|thumb|Boeing B-17F [[Engineering:Radar|radar]] bombing through clouds: Bremen, Germany, on {{Nowrap|13 November}} 1943]]

Operation Pointblank opened with attacks on targets in Western Europe. General Ira C. Eaker and the Eighth Air Force placed highest priority on attacks on the German aircraft industry, especially fighter assembly plants, engine factories, and ball-bearing manufacturers.<ref name="Carey Pointblank" /> Attacks began in April 1943 on heavily fortified key industrial plants in [[Place:Bremen|Bremen]] and Recklinghausen.<ref name="Bowman.8" />

Since the airfield bombings were not appreciably reducing German fighter strength, additional B-17 groups were formed, and Eaker ordered major missions deeper into Germany against important industrial targets. The 8th Air Force then targeted the ball-bearing factories in Schweinfurt, hoping to cripple the war effort there. The first raid on {{Nowrap|17 August}} 1943 did not result in critical damage to the factories, with the 230 attacking B-17s being intercepted by an estimated 300 Luftwaffe fighters. The Germans shot down 36 aircraft with the loss of 200 men, and coupled with a raid earlier in the day against Regensburg, a total of 60 B-17s were lost that day.<ref name="Hess.pp59-60" />

A second attempt on Schweinfurt on 14 October 1943 later came to be known as "Black Thursday".<ref name="Hess.pp65-67" /> While the attack was successful at disrupting the entire works, severely curtailing work there for the remainder of the war, it was at an extreme cost.<ref name="Bowman.22" /> Of the 291 attacking Fortresses, 60 were shot down over Germany, five crashed on approach to Britain, and 12 more were scrapped due to damage&nbsp;– a loss of 77 B-17s.<ref name="AFM.76-9" /> Additionally, 122 bombers were damaged and needed repairs before their next flights. Of 2,900 men in the crews, about 650 did not return, although some survived as [[Social:Prisoner of war|prisoners of war]]. Only 33 bombers landed without damage. These losses were a result of concentrated attacks by over 300 German fighters.<ref name="Hess.p64" />

[[File:B-17G formation on bomb run.jpg|thumb|B-17G of the 384th Bomb Group on the bomb run]]

Such high losses of aircrews could not be sustained, and the USAAF, recognizing the vulnerability of heavy bombers to interceptors when operating alone, suspended daylight bomber raids deep into Germany until the development of an escort fighter that could protect the bombers all the way from the United Kingdom to Germany and back. At the same time, the German nightfighting ability noticeably improved to counter the nighttime strikes, challenging the conventional faith in the cover of darkness.<ref name="Weigley.341" /> The 8th Air Force alone lost 176 bombers in October 1943,<ref name="Hess.p67" /> and was to suffer similar casualties on {{Nowrap|11 January}} 1944 on missions to Oschersleben, Halberstadt, and Brunswick. Lieutenant General James Doolittle, commander of the 8th, had ordered the second Schweinfurt mission to be cancelled as the weather deteriorated, but the lead units had already entered hostile air space and continued with the mission. Most of the escorts turned back or missed the rendezvous, and as a result, 60 B-17s were destroyed.<ref name="Hess.69-71" /><ref name="C&W.151" />

A third raid on Schweinfurt on {{Nowrap|24 February}} 1944 highlighted what came to be known as "Big Week",<ref name="Weigley.340-1" /> during which the bombing missions were directed against German aircraft production.<ref name="Weigley.341" /> German fighters needed to respond, and the [[Engineering:North American P-51 Mustang|North American P-51 Mustang]] and [[Engineering:Republic P-47 Thunderbolt|Republic P-47 Thunderbolt]] fighters (equipped with improved [[Engineering:Drop tank|drop tank]]s to extend their range) accompanying the American heavies all the way to and from the targets engaged them.<ref name="Weigley.342" /> The escort fighters reduced the loss rate to below 7%, with a total of 247 B-17s lost in 3,500 [[Social:Sortie|sortie]]s while taking part in the Big Week raids.<ref name="C&W.162" />

By September 1944, 27 of the 42 bomb groups of the 8th Air Force and six of the 21 groups of the 15th Air Force used B-17s. Losses to flak continued to take a high toll of heavy bombers through 1944, but the war in Europe was being won by the Allies. And by {{Nowrap|27 April}} 1945, 2 days after the last heavy bombing mission in Europe, the rate of aircraft loss was so low that replacement aircraft were no longer arriving and the number of bombers per bomb group was reduced. The Combined Bomber Offensive was effectively complete.<ref name="USAAF.04-45" />

=== Pacific Theater ===
[[File:NARA 28-1277a.jpg|thumb| B-17C AAF S/N ''40-2074'' at Hickam Field: An onboard fire burnt the aircraft in two shortly after landing on {{Nowrap|7 December}} 1941. One crewman was killed by a Zero attack.<ref name="A&K.1" />]]

On 7 December 1941, a group of 12 B-17s of the 38th (four B-17C) and 88th (eight B-17E) Reconnaissance Squadrons, en route to reinforce the Philippines, was flown into Pearl Harbor from Hamilton Field, California, arriving while the surprise attack on Pearl Harbor was going on. Leonard "Smitty" Smith Humiston, co-pilot on First Lieutenant Robert H. Richards' B-17C, AAF S/N ''40-2049'', reported that he thought the U.S. Navy was giving the flight a 21-gun salute to celebrate the arrival of the bombers, after which he realized that Pearl Harbor was under attack. The Fortress came under fire from Japanese fighter aircraft, though the crew was unharmed with the exception of one member who suffered an abrasion on his hand. Japanese activity forced them to divert from Hickam Field to Bellows Field. On landing, the aircraft overran the runway and ran into a ditch, where it was then strafed. Although initially deemed repairable, ''40-2049'' (11th BG / 38th RS) received more than 200 bullet holes and never flew again. Ten of the 12 Fortresses survived the attack.<ref name="A&K.2" />

[[File:Typhoon McGoon II, New Caledonia, January 1943.jpg|left|thumb|B-17E BO AAF S/N ''41-9211'' <br /> ''Typhoon McGoon II'' of the 11th BG / 98th BS, taken in January 1943 in New Caledonia: The antennae mounted upon the nose were used for radar tracking surface vessels.]]

By 1941, the {{wipe|Far East Air Force (United States)}} (FEAF) based at Clark Field in the Philippines had 35 B-17s, with the War Department eventually planning to raise that to 165.<ref name="bloody p55-6" /> When the FEAF received word of the attack on Pearl Harbor, General Lewis H. Brereton sent his bombers and fighters on various patrol missions to prevent them from being caught on the ground. Brereton planned B-17 raids on Japanese airfields in Formosa, in accordance with Rainbow 5 war plan directives, but this was overruled by General Douglas MacArthur.<ref name="Bloody p163" /> A series of disputed discussions and decisions, followed by several confusing and false reports of air attacks, delayed the authorization of the sortie. By the time the B-17s and escorting [[Engineering:Curtiss P-40 Warhawk|Curtiss P-40 Warhawk]] fighters were about to get airborne, they were destroyed by Japanese bombers of the 11th Air Fleet. The FEAF lost half its aircraft during the first strike,<ref name="Bloody p166-7" /> and was all but destroyed over the next few days.{{citation needed|date=October 2017}}

Another early World War II Pacific engagement, on {{Nowrap|10 December}} 1941, involved Colin Kelly, who reportedly crashed his B-17 into the Japanese battleship ''Haruna'', which was later acknowledged as a near bomb miss on the heavy cruiser ''Ashigara''. Nonetheless, this deed made him a celebrated war hero. Kelly's B-17C AAF S/N ''40-2045'' (19th BG / 30th BS) crashed about {{convert|6|mi|km|sigfig=1|abbr=on}} from Clark Field after he held the burning Fortress steady long enough for the surviving crew to bail out. Kelly was posthumously awarded the Distinguished Service Cross.<ref name="Sal.p64" />
Noted Japanese ace Saburō Sakai is credited with this kill, and in the process, came to respect the ability of the Fortress to absorb punishment.<ref name="Sakai" />

B-17s were used in early battles of the Pacific with little success, notably the Battle of Coral Sea<ref name="WoF p96" /> and Battle of Midway.<ref name="Sword p180,329" /> While there, the {{wipe|Fifth Air Force}} B-17s were tasked with disrupting the Japanese sea lanes. Air Corps doctrine dictated bombing runs from high altitude, but they soon found only 1% of their bombs hit targets. However, B-17s were operating at heights too great for most A6M Zero fighters to reach.

The B-17's greatest success in the Pacific was in the Battle of the Bismarck Sea, in which aircraft of this type were responsible for damaging and sinking several Japanese transport ships. On 2 March 1943, six B-17s of the 64th Squadron flying at {{convert|10000|ft|m|sigfig=1|abbr=on}} attacked a major Japanese troop convoy off New Guinea, using skip bombing to sink {{ship|SS|Kyokusei Maru||2}}, which carried 1,200 army troops, and damage two other transports, ''Teiyo Maru'' and ''Nojima''. On 3 March 1943, 13 B-17s flying at {{convert|7000|ft|m|sigfig=1|abbr=on}} bombed the convoy, forcing the convoy to disperse and reducing the concentration of their anti-aircraft defenses. The B-17s attracted a number of [[Engineering:Mitsubishi A6M Zero|Mitsubishi A6M Zero]] fighters, which were in turn attacked by the P-38 Lightning escorts. One B-17 broke up in the air, and its crew was forced to take to their parachutes. Japanese fighter pilots machine-gunned some of the B-17 crew members as they descended and attacked others in the water after they landed.<ref name="Gillison, pp. 692-693">Gillison, pp. 692–93</ref> Five of the Japanese fighters strafing the B-17 aircrew were promptly engaged and shot down by three Lightnings, though these were also then lost.<ref name="historynet">{{cite journal |url=http://www.historynet.com/battle-of-the-bismarck-sea.htm |title=Battle of the Bismarck Sea |first=Lawrence |last=Spinetta |date=November 2007 |journal=World War II |issn=0898-4204|access-date=2 August 2013}}</ref> The allied fighter pilots claimed 15 Zeros destroyed, while the B-17 crews claimed five more.<ref name="Gillison, pp. 692-693"/><ref name="Watson, pp. 144-145">Watson, pp. 144–45</ref> Actual Japanese fighter losses for the day were seven destroyed and three damaged.<ref name="Gamble 2010 313">Gamble, pp. 313</ref><ref name="awm" /> The remaining seven transports and three of the eight destroyers were then sunk by a combination of low level strafing runs by {{wipe|Royal Australian Air Force}} Beaufighters, and skip bombing by USAAF [[Engineering:North American B-25 Mitchell|North American B-25 Mitchell]]s at {{convert|100|ft|m|abbr=on}}, while B-17s claimed five hits from higher altitudes.<ref name="Frisbee" /> On the morning of 4 March 1943, a B-17 sank the destroyer ''Asashio'' with a {{convert|500|lb|kg|abbr=on}} bomb while she was picking up survivors from ''Arashio''.<ref>{{harvnb|Morison|1950|p=61}}</ref>

At their peak, 168 B-17 bombers were in the Pacific theater in September 1942, but already in mid-1942 Gen. Arnold had decided that the B-17 was unsuitable for the kind of operations required in the Pacific and made plans to replace all of the B-17s in the theater with B-24s (and later, B-29s) as soon as they became available. Although the conversion was not complete until mid-1943, B-17 combat operations in the Pacific theater came to an end after a little over a year.<ref>Kenney, George C. ''General Kenney Reports''. New York: Duall, Sloan and Pearce, 1949.</ref> Surviving aircraft were reassigned to the 54th Troop Carrier Wing's special airdrop section and were used to drop supplies to ground forces operating in close contact with the enemy. Special airdrop B-17s supported Australian commandos operating near the Japanese stronghold at Rabaul, which had been the primary B-17 target in 1942 and early 1943.<ref>Jacobson 1945 {{page needed|date=January 2012}}</ref>

B-17s were still used in the Pacific later in the war, however, mainly in the combat search and rescue role. A number of B-17Gs, redesignated B-17Hs and later SB-17Gs, were used in the Pacific during the final year of the war to carry and drop lifeboats to stranded bomber crews who had been shot down or crashed at sea.<ref>{{Cite web|url=http://www.pbyrescue.com/Aircraft/b-17h.htm|title=The B-17H "Flying Dutchman"|website=www.pbyrescue.com|access-date=24 March 2017|archive-url=https://web.archive.org/web/20170420225027/http://www.pbyrescue.com/Aircraft/b-17h.htm|archive-date=20 April 2017|url-status=dead}}</ref> These aircraft were nicknamed Dumbos, and remained in service for many years after the end of World War II.<ref>A-1 lifeboat</ref>

=== Bomber defense ===
[[File:Bomber stream.jpg|thumb|Part of a USAAF stream of over 1,000 B-17s]]
Before the advent of long-range fighter escorts, B-17s had only their .50 caliber M2 Browning machine guns to rely on for defense during the bombing runs over Europe. As the war intensified, Boeing used feedback from aircrews to improve each new variant with increased armament and armor.<ref name="Boeing" /> Defensive armament increased from four {{convert|0.50|in|mm|sigfig=3|abbr=on}} machine guns and one {{convert|0.30|in|mm|sigfig=3|abbr=on}} nose machine gun in the B-17C, to thirteen {{convert|0.50|in|mm|sigfig=3|abbr=on}} machine guns in the B-17G. But because the bombers could not maneuver when attacked by fighters and needed to be flown straight and level during their final bomb run, individual aircraft struggled to fend off a direct attack.

[[File:Bundesarchiv Bild 101I-657-6304-24, Luftwaffe, Modelle eines Bombers und Jägers.jpg|thumb|upright|left|German training model on how to attack a "flying porcupine" (''fliegendes Stachelschwein'')]]
[[File:Combatbox.gif|thumb|"Combat boxes" of 12 B-17 during bombing missions]]

A 1943 survey by the USAAF found that over half the bombers shot down by the Germans had left the protection of the main formation.<ref name="B-17.de 2" /> To address this problem, the United States developed the bomb-group formation, which evolved into the staggered combat box formation in which all the B-17s could safely cover any others in their formation with their machine guns. This made a formation of bombers a dangerous target to engage by enemy fighters.<ref name="Manual 2" /> In order to more quickly form these formations, assembly ships, planes with distinctive paint schemes, were utilized to guide bombers into formation, saving assembly time.<ref name="MAH">{{cite web |title=Why Use Colourful Camouflage in World War 2? – Assembly Ships |url=https://www.youtube.com/watch?v=WYm1QEV69bo | archive-url=https://ghostarchive.org/varchive/youtube/20211123/WYm1QEV69bo| archive-date=2021-11-23 | url-status=live|website=Youtube |publisher=Military Aviation History}}{{cbignore}}</ref><ref name="Polka Dot">{{cite web |title=Polka Dot Warriors > Vintage Wings of Canada |url=http://www.vintagewings.ca/VintageNews/Stories/tabid/116/articleType/ArticleView/articleId/477/language/en-CA/Polka-Dot-Warriors.aspx |website=www.vintagewings.ca |publisher=Vintage Wings |access-date=7 February 2019 |archive-date=1 December 2019 |archive-url=https://web.archive.org/web/20191201121322/http://www.vintagewings.ca/VintageNews/Stories/tabid/116/articleType/ArticleView/articleId/477/language/en-CA/Polka-Dot-Warriors.aspx |url-status=dead }}</ref>  ''Luftwaffe'' fighter pilots likened attacking a B-17 combat box formation to encountering a ''fliegendes Stachelschwein'', "flying porcupine", with dozens of machine guns in a combat box aimed at them from almost every direction. However, the use of this rigid formation meant that individual aircraft could not engage in evasive maneuvers: they had to fly constantly in a straight line, which made them vulnerable to German flak. Moreover, German fighter aircraft later developed the tactic of high-speed strafing passes rather than engaging with individual aircraft to inflict damage with minimum risk.{{citation needed|date=October 2017}} As a result, the B-17s' loss rate was up to 25% on some early missions. It was not until the advent of long-range fighter escorts (particularly the [[Engineering:North American P-51 Mustang|North American P-51 Mustang]]) and the resulting degradation of the ''Luftwaffe'' as an effective interceptor force between February and June 1944, that the B-17 became strategically potent.{{citation needed|date=October 2017}}

[[File:B-17 Schweinfurt.jpg|thumb|Formation flying through dense flak over Merseburg, Germany]]

The B-17 was noted for its ability to absorb battle damage, still reach its target and bring its crew home safely.<ref name="Manual" /><ref name="browne" /><ref name="Johnsen 2006" /> Wally Hoffman, a B-17 pilot with the Eighth Air Force during World War&nbsp;II, said, "The plane can be cut and slashed almost to pieces by enemy fire and bring its crew home."<ref name="Hoffman" /> Martin Caidin reported one instance in which a B-17 suffered a midair collision with a [[Engineering:Focke-Wulf Fw 190|Focke-Wulf Fw 190]], losing an engine and suffering serious damage to both the starboard horizontal stabilizer and the vertical stabilizer, and being knocked out of formation by the impact. The B-17 was reported as shot down by observers, but it survived and brought its crew home without injury.<ref name="Caidin.p86" /> Its toughness was compensation for its shorter range and lighter bomb load compared to the B-24 and British [[Engineering:Avro Lancaster|Avro Lancaster]] heavy bombers.{{Clarify|is this statement backed by the ref for the following sentence?|date=June 2010}} Stories circulated of B-17s returning to base with tails shredded, engines destroyed and large portions of their wings destroyed by [[Social:Anti-aircraft warfare|flak]].<ref name="DurableB-17Colorado" /> This durability, together with the large operational numbers in the Eighth Air Force and the fame achieved by the ''Memphis Belle'', made the B-17 a key bomber aircraft of the war. Other factors such as combat effectiveness and political issues also contributed to the B-17's success.<ref name="B17vB24" />

=== Luftwaffe attacks ===
[[File:B-17 Damage Cologne.jpg|thumb|B-17G ''43-38172'' of the 8th AF 398th BG 601st BS which was damaged on a bombing mission over Cologne, Germany, on {{Nowrap|15 October}} 1944; the bombardier was killed.<ref>[http://www.398th.org/Images/Images_Aircraft_B-17/Aircraft/43-38172-3O-P_19441015_JBk.html "43-38172"]. ''398th.org''. Retrieved: 24 January 2012.</ref>]]
After examining wrecked B-17s and B-24s, Luftwaffe officers discovered that on average it took about 20 hits with [[Engineering:MG 151 cannon|20 mm]] shells fired from the rear to bring them down.<ref name="AFM.76-9" /> Pilots of average ability hit the bombers with only about two percent of the rounds they fired, so to obtain 20 hits, the average pilot had to fire one thousand {{convert|20|mm|in|abbr=on}} rounds at a bomber.<ref name="AFM.76-9" /> Early versions of the [[Engineering:Focke-Wulf Fw 190|Fw 190]], one of the best German interceptor fighters, were equipped with two {{convert|20|mm|in|abbr=on}} [[Engineering:MG FF cannon|MG FF]] cannons, which carried only 500 rounds when belt-fed (normally using 60-round [[Engineering:Drum magazine|drum magazine]]s in earlier installations), and later with the better [[Engineering:MG 151 cannon|Mauser MG 151/20]] cannons, which had a longer effective range than the MG FF weapon. Later versions carried four or even six MG 151/20 cannon and twin [[Engineering:MG 131 machine gun|13&nbsp;mm machine guns]]. The German fighters found that when attacking from the front, where fewer defensive guns were mounted (and where the pilot was exposed and not protected by armor as he was from the rear), it took only four or five hits to bring a bomber down.<ref name="AFM.76-9" />

To rectify the Fw 190's shortcomings, the number of cannons fitted was doubled to four, with a corresponding increase in the amount of ammunition carried, creating the ''Sturmbock'' bomber destroyer version. This type replaced the vulnerable twin-engine ''Zerstörer'' heavy fighters which could not survive interception by P-51 Mustangs flying well ahead of the combat boxes in an air supremacy role starting very early in 1944 to clear any Luftwaffe defensive fighters from the skies. By 1944, a further upgrade to Rheinmetall-Borsig's {{convert|30|mm|in|abbr=on}} [[Engineering:MK 108 cannon|MK 108 cannon]]s mounted either in the wing, or in underwing, conformal mount gun pods, was made for the ''Sturmbock'' Focke-Wulfs as either the /R2 or /R8 field modification kits, enabling aircraft to bring a bomber down with just a few hits.<ref name="AFM.76-9" />

[[File:B-17G Destroyed by Flak.jpg|thumb|left|B-17G-15-BO ''Wee Willie'', 322d BS, 91st BG, after direct flak hit on her 128th mission.<ref>Bowers 1976, p. 177.</ref>]]
The adoption of the [[Engineering:21 cm Nebelwerfer 42|21 cm Nebelwerfer]]-derived ''Werfer-Granate 21'' (Wfr. Gr. 21) rocket mortar by the Luftwaffe in mid-August 1943 promised the introduction of a major "stand-off" style of offensive weapon&nbsp;– one strut-mounted tubular launcher was fixed under each wing panel on the Luftwaffe's single-engine fighters, and two under each wing panel of a few twin-engine [[Engineering:Messerschmitt Bf 110|Bf 110]] daylight ''Zerstörer'' aircraft.<ref name="AFM.76-9" /> However, due to the slow 715&nbsp;mph velocity and characteristic ballistic drop of the fired rocket (despite the usual mounting of the launcher at about 15° upward orientation), and the small number of fighters fitted with the weapons, the Wfr. Gr. 21 never had a major effect on the combat box formations of Fortresses.<ref name="AFM.76-9" /> The Luftwaffe also fitted heavy-caliber ''Bordkanone''-series 37, 50 and even {{convert|75|mm|in|sigfig=3|abbr=on}} cannon as anti-bomber weapons on twin-engine aircraft such as the special [[Engineering:Junkers Ju 88|Ju 88P]] fighters, as well as one model of the [[Engineering:Messerschmitt Me 410|Me 410]] ''Hornisse'' but these measures did not have much effect on the American strategic bomber offensive. The [[Engineering:Messerschmitt Me 262|Me 262]], however, had moderate success against the B-17 late in the war. With its usual nose-mounted armament of four [[Engineering:MK 108 cannon|MK 108 cannon]]s, and with some examples later equipped with the R4M rocket, launched from underwing racks, it could fire from outside the range of the bombers' {{convert|.50|in|mm|sigfig=3|abbr=on}} defensive guns and bring an aircraft down with one hit,<ref name="Schollars" /> as both the MK 108's shells and the R4M's warheads were filled with the "shattering" force of the strongly brisant [[Chemistry:RDX|Hexogen]] military explosive.

=== Luftwaffe-captured B-17s ===
[[File:B17 kg200.jpg|thumb|Captured B-17F-27-BO in ''Luftwaffe'' markings, the USAAF-named "Wulfe-Hound", ''41-24585'', of the 360th BS/303rd BG, was downed on 12 December 1942 near Leeuwarden, Netherlands, while on a raid on Rouen, {{wipe|France}}. The first Flying Fortress to fall intact into German hands, it was operated by ''Kampfgeschwader'' 200 from March 1944.<ref>Thomas, Geoffrey J., and Ketley, Barry, "KG 200 – The Luftwaffe's Most Secret Unit", Hikoku Publications Ltd., Crowborough, East Sussex, UK, 2003, {{ISBN|1-902109-33-3}}, pp. 57–58, 66.</ref>]]

During World War II approximately 40 B-17s were captured and refurbished by Germany after crash-landing or being forced down, with about a dozen put back into the air. Given German ''Balkenkreuz'' national markings on their wings and fuselage sides, and [[Swastika|swastika]] tail fin–flashes, the captured B-17s were used to determine the B-17's vulnerabilities and to train German interceptor pilots in attack tactics.<ref name="WoF p89" /> Others, with the cover designations Dornier Do 200 and Do 288, were used as long-range transports by the ''Kampfgeschwader'' 200 special duties unit, carrying out agent drops and supplying secret airstrips in the Middle East and North Africa. They were chosen specifically for these missions as being more suitable for this role than other available German aircraft; they never attempted to deceive the Allies and always wore full ''Luftwaffe'' markings.<ref name="Donald Am p23" /><ref name="Wixley p30" /> One B-17 of KG200, bearing the ''Luftwaffe's'' KG 200 ''Geschwaderkennung'' (combat wing code) markings ''A3+FB'', was interned by Spain when it landed at [[Place:Valencia|Valencia]] airfield, {{Nowrap|27 June}} 1944, remaining there for the rest of the war.<ref name="Northstar" /> It has been alleged that some B-17s kept their Allied markings and were used by the ''Luftwaffe'' in attempts to infiltrate B-17 bombing formations and report on their positions and altitudes.<ref>{{Cite book|title=Aluminum Castles: WWII from a gunner's view|last=Richardson|first=Wilbur|publisher=Cantemos|date=26 May 2012|pages=29–30|quote=We also reported seeing a B17 flying at a safe distance from the formation. This mystery fortress shadowed the formation inbound from the Rhine river and we were informed others had seen it back across Belgium on the way out. A fortress manned by the enemy created an unsettling feeling in all of us.}}</ref> According to these allegations, the practice was initially successful, but Army Air Force combat aircrews quickly developed and established standard procedures to first warn off, and then fire upon any "stranger" trying to join a group's formation.<ref name="Northstar" />

=== Soviet-interned B-17s ===
The U.S. did not offer B-17s to the Soviet Union as part of its war materiel assistance program, but at least 73 aircraft were acquired by the {{wipe|Soviet Air Force}}. These aircraft had landed with mechanical trouble during the shuttle bombing raids over Germany or had been damaged by a ''Luftwaffe'' raid in Poltava. The Soviets restored 23 to flying condition and concentrated them in the 890th Bomber Regiment of the 45th Bomber Aviation Division,<ref>{{cite web|last=Holm |first=Michael |title=890th Bryanskiy Bomber Aviation Regiment|url=https://www.ww2.dk/new/air%20force/regiment/bap/890bap.htm}}</ref> but they never saw combat. In 1946 (or 1947, according to Holm), the regiment was assigned to the Kazan factory (moving from Baranovichi) to help the Soviet effort to reproduce the more advanced [[Engineering:Boeing B-29 Superfortress|Boeing B-29]] as the [[Engineering:Tupolev Tu-4|Tupolev Tu-4]].<ref name="Gordon p. 479">Gordon 2008, p. 479.</ref>

=== Swiss-interned B-17s ===
During the Allied bomber offensive, U.S. and British bombers sometimes flew into Swiss airspace, either because they were damaged or, on rare occasions, accidentally bombing Swiss cities. Swiss aircraft attempted to intercept and force individual aircraft to land, interning their crews; one Swiss pilot was killed, shot down by a U.S. bomber crew in September 1944.{{cn|date=July 2023}}

Official Swiss records identify 6,501 airspace violations during the course of the war, with 198 foreign aircraft landing on Swiss territory and 56 aircraft crashing there. In October 1943, the Swiss interned Boeing B-17F-25-VE, tail number 25841, and its U.S. flight crew after the Flying Fortress developed engine trouble after a raid over Germany and was forced to land. The aircraft was turned over to the {{wipe|Swiss Air Force}}, who then flew the bomber until the end of the war, using other interned but non-airworthy B-17s for spare parts. The bomber's topside surfaces were repainted a dark [[Olive drab|olive drab]], but retained its light gray under wing and lower fuselage surfaces. It carried Swiss national white cross insignia in red squares on both sides of its rudder, fuselage sides, and on the topside and underside wings. The B-17F also carried light gray flash letters "RD" and "I" on either side of the fuselage's Swiss national insignia.<ref name="Cravens, Wesley 1956" />

=== Japanese-captured B-17s ===
[[File:B17jp.jpg|thumb|This captured USAAF Boeing B-17D, in Japanese livery, was flown to Japan for technical evaluation]]

In 1942, Japanese technicians and mechanics rebuilt three damaged B-17s, one "D" and two "E" series, using parts salvaged from abandoned B-17 wrecks in the Philippines and the Java East Indies.<ref>{{cite web| url = https://www.historynet.com/japans-fleet-flying-forts.htm| title = The Surprising Story of Japan's B-17 Fleet| date = 26 January 2018}}</ref> The three bombers, which still contained their top-secret [[Norden bombsight]]s, were ferried to Japan where they underwent extensive technical evaluation by the ''Giken'', the {{wipe|Imperial Japanese Army Air Force}}'s Air Technical Research Institute (Koku Gijutsu Kenkyujo) at Tachikawa's air field. The "D" model, later deemed an obsolescent design, was used in Japanese training and propaganda films. The two "E"s were used to develop air combat tactics for use against B-17s; they were also used as enemy aircraft in pilot and crew training films. One of the two "E"s was photographed late in the war by U. S. aerial recon. It was code-named "Tachikawa 105" after the mystery aircraft's wingspan (104 feet) but not correctly identified as a captured B-17 until after the war. No traces of the three captured Flying Fortresses were ever found in Japan by Allied occupation forces. The bombers were assumed either lost by various means or scrapped late in the war for their vital war materials.<ref name="Bowers Boeing p314" />

=== Postwar history ===
==== U.S. Air Force ====
[[File:QB-17 Flying Fortress Drones over New Mexico 1946.jpg|thumb|left|BQ-17 Flying Fortress drones over New Mexico, April 1946]]

After World War II, the B-17 was quickly phased out of use as a bomber and the Army Air Forces retired most of its fleet. Flight crews ferried the bombers back across the Atlantic to the United States where the majority were sold for scrap and melted down, although many remained in use in second-line roles such as VIP transports, air-sea rescue and photo-reconnaissance.<ref name="Swan mil p80" /><ref name="Bowers Boeing p290" /> Strategic Air Command (SAC), established in 1946, used reconnaissance B-17s (at first called F-9 [''F'' for ''Fotorecon''], later RB-17) until 1949.<ref name="Bowers Boeing p310-1" /><ref name="Knaack bomber p465" />

[[File:Boeing SB-17G of the 5th Rescue Squadron, Flight D.jpg|thumb|SB-17G of the USAF 5th Rescue Squadron c. 1950]]

The USAF Air Rescue Service of the Military Air Transport Service (MATS) operated B-17s as so-called "Dumbo" air-sea rescue aircraft. Work on using B-17s to carry airborne lifeboats had begun in 1943, but they entered service in the European theater only in February 1945. They were also used to provide search and rescue support for [[Engineering:Boeing B-29 Superfortress|B-29]] raids against Japan. About 130 B-17s were converted to the air-sea rescue role, at first designated B-17H and later SB-17G. Some SB-17s had their defensive guns removed, while others retained their guns to allow use close to combat areas. The SB-17 served through the Korean War, remaining in service with USAF until the mid-1950s.<ref name="Bowers Boeing p303-4" /><ref name="WoF p86" /><ref name="WoF p89-0" />

In 1946, surplus B-17s were chosen as [[Engineering:Unmanned aerial vehicle|drone aircraft]] for atmospheric sampling during the Operation Crossroads atomic bomb tests, being able to fly close to or even through the [[Physics:Mushroom cloud|mushroom cloud]]s without endangering a crew. This led to more widespread conversion of B-17s as drones and drone control aircraft, both for further use in atomic testing and as targets for testing [[Engineering:Surface-to-air missile|surface-to-air]] and [[Engineering:Air-to-air missile|air-to-air missile]]s.<ref name="WoF p91" /> {{nowrap|One hundred and seven B-17s}} were converted to drones.<ref name="Flight Sperry" /> The last operational mission flown by a USAF Fortress was conducted on {{Nowrap|6 August}} 1959, when a DB-17P, serial'' 44-83684 '', directed a QB-17G, out of {{wipe|Holloman Air Force Base}}, New Mexico, as a target for an AIM-4 Falcon air-to-air missile fired from a [[Engineering:McDonnell F-101 Voodoo|McDonnell F-101 Voodoo]]. A retirement ceremony was held several days later at Holloman AFB, after which ''44-83684'' was retired.{{Citation needed|date=October 2010}} It was subsequently used in various films and in the 1960s television show ''12 O'Clock High'' before being retired to the Planes of Fame aviation museum in Chino, California.<ref>{{cite web |url = http://warbirdregistry.org/b17registry/b17-4483684.html |title = Warbird Registry – Boeing B-17 Flying Fortress  |website = warbirdregistry.org }}</ref> Perhaps the most famous B-17, the ''Memphis Belle'', has been restored – with the B-17D ''The Swoose'' under way – to her World War II wartime appearance by the National Museum of the United States Air Force at Wright-Patterson Air Force Base, Ohio.<ref name="NMAF Memphis" />

==== U.S. Navy and Coast Guard ====
[[File:US Navy PB-1W.jpg|thumb|Under project '''Cadillac&nbsp;II''', an AN/APS-20 radar was fitted onto the B-17G, making the PB-1W one of the first Airborne early warning aircraft.]]

During the last year of World War II and shortly thereafter, the United States Navy (USN) acquired 48 ex-USAAF B-17s for patrol and air-sea rescue work. The first two ex-USAAF B-17s, a B-17F (later modified to B-17G standard) and a B-17G were obtained by the Navy for various development programs.<ref name="Bowers Boeing p310-1" /> At first, these aircraft operated under their original USAAF designations, but on 31 July 1945 they were assigned the naval aircraft designation PB-1, a designation which had originally been used in 1925 for the Boeing Model 50 experimental flying boat.<ref name="Swan Navy" />

Thirty-two B-17Gs<ref name="DABASv2 p661" /> were used by the Navy under the designation PB-1W, the suffix -W indicating an airborne early warning role. A large radome for an S-band [[Engineering:List of radars|AN/APS-20]] search radar was fitted underneath the fuselage and additional internal fuel tanks were added for longer range, with the provision for additional underwing fuel tanks. Originally, the B-17 was also chosen because of its heavy defensive armament, but this was later removed. These aircraft were painted dark blue, the standard Navy paint scheme which had been adopted in late 1944.<ref name="Bowers Boeing p310-1" /><ref name="Swan Navy" /> PB-1Ws continued in USN service until 1955, gradually being phased out in favor of the Lockheed WV-2 (known in the USAF as the EC-121, a designation adopted by the USN in 1962), a military version of the [[Engineering:Lockheed Constellation|Lockheed 1049 Constellation]] commercial airliner.{{Citation needed|date=October 2017}}

[[File:US Coast Guard PB-1G in flight.jpg|thumb|The U.S. Coast Guard PB-1G carried a droppable lifeboat.]]

In July 1945, 16 B-17s were transferred to the Coast Guard via the Navy; these aircraft were initially assigned U.S. Navy Bureau Numbers (BuNo), but were delivered to the Coast Guard designated as PB-1Gs beginning in July 1946.<ref name="Bowers Boeing p310-1" /><ref name="WoF p89-0" /> Coast Guard PB-1Gs were stationed at a number of bases in the U.S. and Newfoundland, with five at Coast Guard Air Station Elizabeth City, North Carolina, two at CGAS San Francisco, two at NAS Argentia, Newfoundland, one at CGAS Kodiak, Alaska, and one in Washington state.<ref name="WoF p89-0" /> They were used primarily in the "Dumbo" air-sea rescue role, but were also used for [[Earth:International Ice Patrol|iceberg patrol]] duties and for photo mapping. The Coast Guard PB-1Gs served throughout the 1950s, the last example not being withdrawn from service until 14 October 1959.<ref name="Bowers Boeing p310-1" /><ref name="USCG" />

=== Special operations ===
B-17s were used by the CIA front companies Civil Air Transport, Air America and Intermountain Aviation for special missions. These included B-17G ''44-85531'', registered as N809Z. These aircraft were primarily used for agent drop missions over the People's Republic of China, flying from Taiwan, with Taiwanese crews. Four B-17s were shot down in these operations.<ref>Pocock, Chris. ''The Black Bats: CIA Spy Flights Over China From Taiwan, 1951–1969''. Atglen, Pennsylvania: Schiffer Military History, 2010. {{ISBN|978-0-7643-3513-6}}.</ref>

In 1957 the surviving B-17s had been stripped of all weapons and painted black. One of these Taiwan-based B-17s was flown to Clark Air Base in the Philippines in mid-September, assigned for covert missions into Tibet.

On 28 May 1962, N809Z, piloted by Connie Seigrist and Douglas Price, flew Major James Smith, USAF and Lieutenant Leonard A. LeSchack, USNR to the abandoned Soviet arctic ice station NP 8, as Operation Coldfeet. Smith and LeSchack parachuted from the B-17 and searched the station for several days. On 1 June, Seigrist and Price returned and picked up Smith and LeSchack using a Fulton Skyhook system installed on the B-17.<ref>[http://www.utdallas.edu/library/collections/speccoll/Leeker/b17.pdf "The Boeing B-17s"]. {{webarchive|url=https://web.archive.org/web/20100928084808/http://www.utdallas.edu/library/collections/speccoll/Leeker/b17.pdf |date=28 September 2010 }} ''utdallas.edu''. Retrieved: 25 July 2011.</ref> N809Z was used to perform a Skyhook pick up in the James Bond movie ''Thunderball'' in 1965. This aircraft, now restored to its original B-17G configuration, was on display in the Evergreen Aviation & Space Museum in McMinnville, Oregon until it was sold to the Collings Foundation in 2015.<ref>{{Cite web|url=https://www.collingsfoundation.org/2015/12/b-17-flying-fortress-to-join-cf/|title = B-17 Flying Fortress to join CF - the Collings Foundation}}</ref>

== Operators ==
[[File:World operators of the B-17.png|thumb|400px|Military operators of the B-17]]
[[File:Civil operators of the B-17.png|thumb|400px|Civil operators of the B-17]]

The B-17, a versatile aircraft, served in dozens of USAAF units in theaters of combat throughout World War&nbsp;II, and in other roles for the RAF. Its main use was in Europe, where its shorter range and smaller bombload relative to other aircraft did not hamper it as much as in the Pacific Theater. Peak USAAF inventory (in August 1944) was 4,574 worldwide.<ref name="Baugher Squads" />

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* {{flag|Iran|1925}}
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* {{flag|Nicaragua|1908}}
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== Surviving aircraft ==
<!-- The below sentence has already been adjusted to account for the Dallas airshow collision in November 2022
-->Forty-five planes survive in complete form, 38 in the United States. Four are airworthy.
{{anchor|The Fortress as a symbol}}

== Fortresses as a symbol ==
[[File:Flying Fortress Cartoon.jpg|thumb|The B-17's capacity to repel enemy attacks and still inflict heavy damage upon German military capability and production centers is rendered in this caricature.]]

The B-17 Flying Fortress became symbolic of the United States of America's air power. In a 1943 Consolidated Aircraft poll of 2,500 men in cities where Consolidated advertisements had been run in newspapers, 73% had heard of the B-24 and 90% knew of the B-17.<ref name="Johnsen 2006" />

After the first Y1B-17s were delivered to the Army Air Corps 2nd Bombardment Group, they were used on flights to promote their long range and navigational capabilities. In January 1938, group commander Colonel Robert Olds flew a Y1B-17 from the U.S. east coast to the west coast, setting a transcontinental record of 13 hours 27 minutes. He also broke the west-to-east coast record on the return trip, averaging {{convert|245|mi/h|km/h|abbr=on}} in 11 hours 1 minute.<ref name="Zamzow" /> Six bombers of the 2nd Bombardment Group took off from Langley Field on {{Nowrap|15 February}} 1938 as part of a goodwill flight to [[Place:Buenos Aires|Buenos Aires, Argentina]]. Covering {{convert|12000|mi|km}} they returned on {{Nowrap|27 February}}, with seven aircraft setting off on a flight to Rio de Janeiro, Brazil, three days later.<ref name="WoF p46-7" /> In a well-publicized mission on 12 May of the same year, three Y1B-17s "intercepted" and took photographs of the Italian ocean liner [[Engineering:SS Rex|SS ''Rex'']] {{convert|610|mi|km}} off the Atlantic coast.<ref name="AFM.91-12" />{{NoteTag|This is a commonly misreported error. The ''Rex'' was 725 miles offshore on her last position report as the Y1B-17s were taxiing for takeoff from Mitchel Field, four hours before interception.}}

Many pilots who flew both the B-17 and the B-24 preferred the B-17 for its greater stability and ease in formation flying. The electrical systems were less vulnerable to damage than the B-24's hydraulics, and the B-17 was easier to fly than a B-24 when missing an engine.<ref name="levine1992">{{cite book |title = The Strategic Bombing of Germany, 1940–1945 |url = https://archive.org/details/strategicbombing00levi |url-access = limited |publisher=Praeger |last = Levine |first = Alan J. |year=1992 |location=Westport, Connecticut |pages=[https://archive.org/details/strategicbombing00levi/page/n24 14]–15 |isbn = 0-275-94319-4}}</ref> During the war, the largest offensive bombing force, the Eighth Air Force, had an open preference for the B-17. Lieutenant General Jimmy Doolittle wrote about his preference for equipping the Eighth with B-17s, citing the logistical advantage in keeping field forces down to a minimum number of aircraft types with their individual servicing and spares. For this reason, he wanted B-17 bombers and P-51 fighters for the Eighth. His views were supported by Eighth Air Force statisticians, whose mission studies showed that the Flying Fortress's utility and survivability was much greater than those of the B-24 Liberator.<ref name="Johnsen 2006" /> Making it back to base on numerous occasions, despite extensive battle damage, the B-17's durability became legendary;<ref name="Manual" /><ref name=browne /> stories and photos of B-17s surviving battle damage were widely circulated during the war.<ref name="Johnsen 2006" /> Despite an inferior performance and smaller bombload than the more numerous B-24 Liberators,<ref name="Birdsall 3" /> a survey of Eighth Air Force crews showed a much higher rate of satisfaction with the B-17.<ref name="B-17.de" />

== Notable B-17s ==
[[File:19430201AllAmericanB17inFlight.jpg|thumb|The severely damaged ''All American'' continues to fly after collision with an attacking Bf 109 fighter, eventually landing without crew injuries.]]
<!-- Many of these aircraft already have lengthy articles. This section only needs to be a brief summary of the notability of each aircraft. -->
* ''All American'' – This B-17F survived having her tail almost cut off in a mid-air collision with a [[Engineering:Messerschmitt Bf 109|Bf 109]] over Tunisia but returned safely to base in Algeria.<ref name=WarbirdsNews20130627>{{cite web |title=WWII's B-17 ''All American:'' Separating Fact and Fiction |url=http://www.warbirdsnews.com/warbird-articles/wwiis-b-17-all-american-separating-fact-fiction.html |website=Warbirds News |archive-url=https://web.archive.org/web/20160405014119/http://www.warbirdsnews.com/warbird-articles/wwiis-b-17-all-american-separating-fact-fiction.html |archive-date=5 April 2016 |date=27 June 2013 |url-status=dead |access-date=12 August 2016 }}</ref>
* ''Chief Seattle'' – sponsored by the city of Seattle, she disappeared (MIA) on 14 August 1942<ref>Nose art [http://home.st.net.au/~dunn/usaaf/chiefofseattle.htm photos] clearly shows "Chief Seattle", but often incorrectly reported as "Chief of Seattle"</ref> flying a recon mission for the 19th BG, 435th BS<ref>B-17E SN# 41-2656 at [http://www.pacificwrecks.com/aircraft/b-17/41-2656.html PacificWrecks.com] or MACR report at Fold3.org</ref> and the crew declared dead on 7 December 1945.
* ''Hell's Kitchen'' – B-17F 41-24392 was one of only three early B-17F's in 414th BS to complete more than 100 combat missions.<ref>{{cite web
|url = http://www.reddog1944.com/414th_Squadron_Planes_and_Crews.htm
|title = 414th Squadron Planes and Crews circa 1943
|website = reddog1944.com
|access-date=20 December 2012
}}</ref>
* ''Mary Ann'' – a B-17D that was part of an unarmed flight which left Hamilton Air Field, Novato, California on 6 December 1941 en route to Hickam Field in Hawaii, arriving during the attack on Pearl Harbor. The plane and her crew were immediately forced into action on Wake Island and in the {{wipe|Philippines}} during the outbreak of [[Social:World War II|World War II]]. She became famous when her exploits were featured in ''Air Force'', one of the first of the patriotic war films released in 1943.<ref>{{cite web |url= https://www.imdb.com/title/tt0035616/trivia |title=Trivia |website=[[Social:IMDb|IMDb]] |date=28 May 2013 |access-date=28 May 2013}}</ref>
* ''Memphis Belle'' – one of the first B-17s to complete a tour of duty of 25 missions in the 8th Air Force and the subject of a feature film, now completely restored and on display since 17 May 2018<ref>{{cite news |url = https://www.cnn.com/2018/05/17/politics/memphis-belle-bomber-unveiling-air-force-museum/index.html |title=Memphis Belle bomber newly restored and unveiled at US Air Force museum |first=Andreas |last=Preuss |date=17 May 2018 |publisher=CNN |access-date=2018-05-17 }}</ref> at the {{wipe|National Museum of the U.S. Air Force}} at Wright-Patterson AFB in Dayton, Ohio.
* Milk Wagon - B-17G.  Over the course of its tour of duty, ''Milk Wagon'' set a record in the 3rd Division, possibly the war, for 129 missions without aborting for mechanical failure. <ref>{{Cite web |title=43-37756 |url=http://www.447bg.com/43-37756.htm |access-date=2023-12-30 |website=www.447bg.com}}</ref> 
* ''Miss Every Morning Fix'n'' – B-17C. Previously named 'Pamela'. Stationed in Mackay, Queensland, Australia during World War II. On 14 June 1943, crashed shortly after takeoff from Mackay while ferrying U.S. forces personnel back to Port Moresby, with 40 of the 41 people on board killed. It remains the worst air disaster in Australian history. The sole survivor, Foye Roberts, married an Australian and returned to the States. He died in Wichita Falls, Texas, on 4 February 2004.<ref>{{cite web |last=Choate|first=Trish |title = Going from lucky in love to lucky to be alive in 1943 |url = http://www.timesrecordnews.com/columnists/choate-going-from-lucky-in-love-to-lucky-to-be-alive-in-1943-ep-427243459-339500392.html |website=timesrecordnews.com |access-date=28 October 2016}}</ref>
* ''Murder Inc.'' – A B-17 bombardier wearing the name of the B-17 "Murder Inc." on his jacket was used for propaganda in German newspapers.<ref name="murder inc.">Williams, Kenneth Daniel. [http://www.merkki.com/murderinc.htm "The Saga of Murder, Inc"]. ''World War II – Prisoners of War – Stalag Luft I''. Retrieved: 31 August 2010.</ref>
* ''Old 666'' – B-17E flown by the most highly decorated crew in the Pacific Theater<ref>{{Cite web |url=http://zeamerseagerbeavers.com/old-666-lucy-history/ |title="Old 666"/"Lucy" – A History |last=Hayes |first=Clint |date=23 February 2014 |website=Zeamer's Eager Beavers |language=en-US |access-date=2018-07-26 }}</ref>
* ''Royal Flush'' – B-17F ''42-6087'' from the 100th Bomb Group and commanded on one mission by highly decorated USAAF officer Robert Rosenthal, she was the lone surviving 100th BG B-17 of 10 October 1943 raid against Münster to return to the unit's base at RAF Thorpe Abbotts.<ref>{{cite web |url = https://100thbg.com/index.php?option=com_bombgrp&view=personnel&id=4475&Itemid=334 |title=LT COL Robert ROSENTHAL  |website=100th Bomber Group |language=en-gb |access-date=2018-07-26 }}</ref>
* ''Sir Baboon McGoon'' – B-17F featured in the June 1944 issue of ''Popular Science'' magazine<ref>{{cite magazine |last=Powell |first=Hickman |title=Another Triumph for Yankee 'Know-How' |url = http://www.91stbombgroup.com/photo_history/sir_baboon_mcgoon_news.html |magazine=Popular Science |access-date=2018-07-26 }}</ref> and the 1945 issue of ''Flying'' magazine.<ref>{{cite magazine |url=http://legendsintheirowntime.com/LiTOT/Content/1945/B17_Fl_4505_crash.html |title=Crash Landing |magazine=Flying |date=May 1945 |volume=36 |issue=5 |pages=[http://legendsintheirowntime.com/LiTOT/Content/1945/B17_Fl_4505_crash.pdf 39–42] |first=Harold W. |last=Kulick |access-date=2018-07-26 |archive-date=11 May 2021 |archive-url=https://web.archive.org/web/20210511200231/http://legendsintheirowntime.com/LiTOT/Content/1945/B17_Fl_4505_crash.html |url-status=dead }}</ref> Articles discuss mobile recovery crews following October 1943 belly landing at Tannington, England.
* ''The Swoose'' – Initially nicknamed ''Ole Betsy'' while in service, ''The Swoose'' is the only remaining intact B-17D, built in 1940, the oldest surviving Flying Fortress, and the only surviving B-17 to have seen action in the Philippines campaign (1941–1942); she is in the collection of the National Air and Space Museum and is being restored for final display at the {{wipe|National Museum of the U.S. Air Force}} at Wright-Patterson AFB in Dayton, Ohio.<ref>{{cite web |url = http://www.nationalmuseum.af.mil/news/story.asp?storyID=123106540 |archive-url = https://web.archive.org/web/20121012220403/http://www.nationalmuseum.af.mil/news/story.asp?storyID=123106540 |archive-date=2012-10-12 |title=The Swoose comes home to roost at the National Museum of the U.S. Air Force |first=Sarah |last=Parke |publisher=National Museum of the U.S. Air Force }}</ref> ''The Swoose'' was flown by Frank Kurtz, father of actress Swoosie Kurtz, who named his daughter after the bomber.
* ''Ye Olde Pub'' – A highly damaged B-17 piloted by Charlie Brown that was not shot down by Franz Stigler, as memorialized in the painting ''A Higher Call'' by John D. Shaw.<ref>{{cite web |url = https://www.valorstudios.com/Franz-Stigler-Charlie-Brown.htm |title = A Higher Call: autographed by JG 27 Bf-109 ace Franz Stigler and Charlie Brown of the B-17 "Ye Olde Pub" |website = www.valorstudios.com |access-date = 17 August 2019 |archive-url = https://web.archive.org/web/20190817190904/https://www.valorstudios.com/Franz-Stigler-Charlie-Brown.htm |archive-date = 17 August 2019 |url-status = dead }}</ref>
* ''5 Grand'' – 5,000th B-17 made, emblazoned with Boeing employee signatures, served with the 333rd Bomb Squadron, 96th Bomb Group in Europe. Damaged and repaired after gear-up landing, transferred to 388th Bomb Group. Returned from duty following V-E Day, flown for war bonds tour, then stored at Kingman, Arizona. Following an unsuccessful bid for museum preservation, the aircraft was scrapped.<ref>''Air Classics'' magazine, July 2004, pp. 66–74</ref>

== Accidents and incidents ==

== Noted B-17 pilots and crew members ==
[[File:Maynard-H-Smith.png|thumb|upright|Maynard H. Smith receiving Medal of Honor from Secretary of War Henry L. Stimson]]
[[File:Forrest-L-Vosler.png|thumb|Forrest L. Vosler receiving Medal of Honor from President Roosevelt]]
[[File:Nancy Love and Betty Gillies.jpg|thumb|upright|L–R, Nancy Love, pilot and Betty (Huyler) Gillies, co-pilot, the first women to fly the Boeing B-17 Flying Fortress heavy bomber for the WASP<ref name="museum2" />]]

=== Medal of Honor recipients ===
Many B-17 crew members received military honors and 17 received the Medal of Honor, the highest military decoration awarded by the United States:<ref name="AFM" />
* Brigadier General Frederick Castle (flying as co-pilot) – awarded posthumously for remaining at controls so others could escape damaged aircraft.<ref>Frisbee, John L. "Valor: The Quiet Hero." ''Air Force Magazine'', Volume 68, Issue 5, May 1998.</ref>
* 2nd Lt Robert Femoyer (navigator) – awarded posthumously<ref>Frisbee, John L. "Valor: 'I Am the Captain of My Soul{{' "}}. ''Air Force Magazine'' Volume 68, Issue 5, May 1985.</ref>
* 1st Lt Donald J. Gott (pilot) – awarded posthumously<ref name="Valor at its Highest">Frisbee, John L. "Valor: 'Valor at its Highest{{' "}}. ''Air Force Magazine'' Volume 72, Issue 6, June 1989.</ref>
* 2nd Lt David R. Kingsley (bombardier) – awarded posthumously for tending to injured crew and giving up his parachute to another<ref>Frisbee, John L. "Valor: A Rather Special Award". ''Air Force Magazine'' Volume 73, Issue 8, August 1990.</ref>
* 1st Lt William R. Lawley Jr. – "heroism and exceptional flying skill"<ref>Frisbee, John L. "Valor: One Turning and One Burning". ''Air Force Magazine'' Volume 82, Issue 6, June 1999.</ref>
* Sgt Archibald Mathies (engineer-gunner) – awarded posthumously<ref name="Point of Honor">Frisbee, John L. "Valor: A Point of Honor". ''Air Force Magazine'' Volume 68, Issue 8, August 1985.</ref>
* 1st Lt Jack W. Mathis (bombardier) – posthumously, the first airman in the European theater to be awarded the Medal of Honor<ref>Frisbee, John L. "Valor: A Tale of Two Texans". ''Air Force Magazine'' Volume 69, Issue 3, March 1986.</ref>
* 2nd Lt William E. Metzger Jr. (co-pilot) – awarded posthumously<ref name="Valor at its Highest" />
* 1st Lt Edward Michael<ref>Frisbee, John L. "Valor: Gauntlet of Fire". ''Air Force Magazine'' Volume 68, Issue 8, August 1985.</ref>
* 1st Lt John C. Morgan<ref>Frisbee, John L. "Valor: Crisis in the Cockpit". ''Air Force Magazine'' Volume 67, Issue 1, January 1984.</ref>
* Capt Harl Pease (awarded posthumously)<ref>Frisbee, John L. "Valor: Rabaul on a Wing and a Prayer". ''Air Force Magazine'' Volume 73, Issue 7, July 1990.</ref>
* 2nd Lt Joseph Sarnoski (awarded posthumously)<ref>[http://www.homeofheroes.com/moh/citations_1940_wwii/sarnoski.html "MOH citation of Sarnoski, Joseph R"]. {{Webarchive|url=https://web.archive.org/web/20060623091114/http://www.homeofheroes.com/moh/citations_1940_wwii/sarnoski.html |date=23 June 2006 }} ''Home of Heroes''. Retrieved: 12 January 2007.</ref>
* S/Sgt Maynard H. Smith (gunner)<ref>Frisbee, John L. "Valor: First of the Few". ''Air Force Magazine'' Volume 67, Issue 4, April 1984.</ref>
* 1st Lt Walter E. Truemper (awarded posthumously)<ref name="Point of Honor" />
* T/Sgt Forrest L. Vosler (radio operator)<ref>Frisbee, John L. "Valor: The Right Touch". ''Air Force Magazine'' Volume 81, Issue 9, September 1998.</ref><ref>Half a Wing, Three Engines and a Prayer. Chapter 25, "Jeffrey Bounce Jr."</ref>
* Brigadier General Kenneth Walker Commanding officer of V Bomber Command, killed while leading small force in raid on Rabaul – awarded posthumously<ref>Frisbee, John L. "Valor: Courage and Conviction". ''Air Force Magazine'' Volume 73, Issue 10, October 1990.</ref>
* Maj Jay Zeamer Jr. (pilot) – earned on unescorted reconnaissance mission in Pacific, same mission as Sarnoski<ref>Frisbee, John L. "Valor: Battle Over Bougainville". ''Air Force Magazine'' Volume 68, Issue 12, December 1985.</ref>

=== Other military achievements or events ===
* Lincoln Broyhill (1925–2008), tail-gunner on a B-17 in the 483rd Bombardment Group. He received a Distinguished Unit Citation and set two individual records in a single day: (1) most German jets destroyed by a single gunner in one mission (two), and (2) most German jets destroyed by a single gunner during the entirety of World War II.<ref>{{cite news |first = Joe |last = Holley |title=WWII gunner 'Babe' Broyhill dies: Set record for downing Nazi jets |newspaper =The Washington Post |url = https://www.washingtonpost.com/wp-dyn/content/article/2008/11/27/AR2008112702380.html |date=28 November 2008 |access-date=7 May 2010 }}</ref>
* Allison C. Brooks (1917–2006), a B-17 pilot who was awarded numerous military decorations and was ultimately promoted to the rank of major general and served in active duty until 1971.<ref>{{cite web |url= http://www.af.mil/bios/bio.asp?bioID=4800 |title = Major General Allison C. Brooks |publisher = United States Air Force |access-date=13 February 2008 |url-status=dead |archive-url = https://web.archive.org/web/20040210205832/http://www.af.mil/bios/bio.asp?bioID=4800 |archive-date=10 February 2004 }}</ref>
* 1st Lt Eugene Emond (1921–1998): Lead pilot for ''Man O War&nbsp;II Horsepower Limited''. Received the Distinguished Flying Cross, Air Medal with three oak leaf clusters, American Theater Ribbon and Victory Ribbon. Was part of D-Day and witnessed one of the first German jets when a Me 262A-1a flew through his formation over Germany. One of the youngest bomber pilots in the U.S. Army Air Forces.
* Immanuel J. Klette (1918–1988): Second-generation German-American whose 91 combat missions were the most flown by any Eighth Air Force pilot in World War&nbsp;II.<ref>Freeman 1993, pp. 497–500.</ref>
* Capt Colin Kelly (1915–1941): Pilot of the first U.S. B-17 lost in action.<ref>Frisbee, John L. "Valor: Colin Kelly (He was a Hero in Legend and in Fact)." ''Air Force Magazine'' Volume 77, Issue 6, June 1994.</ref>
* Col Frank Kurtz (1911–1996): The USAAF's most decorated pilot of World War II. Commander of the 463rd Bombardment Group (Heavy), 15th Air Force, Celone Field, Foggia, Italy. Clark Field Philippines attack survivor. [[Social:Olympic Games|Olympic]] bronze medalist in diving (1932), 1944–1945. Father of actress Swoosie Kurtz, herself named for the still-surviving B-17D mentioned above.
* Gen Curtis LeMay (1906–1990): Became head of the Strategic Air Command and Chief of Staff of the USAF.
* Lt Col Nancy Love (1914–1976) and Betty (Huyler) Gillies (1908–1998): The first women pilots to be certified to fly the B-17, in 1943 and to qualify for the Women's Auxiliary Ferrying Squadron.<ref name="museum2" />
* SSgt Alan Magee (1919–2003): B-17 gunner who on 3 January 1943 survived a {{convert|22,000|ft|m|abbr=off|sp=us|adj=on}} freefall after his aircraft was shot down by the Luftwaffe over St. Nazaire.
* Col Robert K. Morgan (1918–2004): Pilot of ''Memphis Belle''.
* Lt Col Robert Rosenthal (1917–2007): Commanded the only surviving B-17, ''Royal Flush'', of a US 8th Air Force raid by the 100th Bomb Group on Münster on 10 October 1943. Completed 53 missions. Earned sixteen medals for gallantry (including one each from Britain and France), and led the raid on Berlin<ref>{{cite web |url = https://100thbg.com/index.php?option=com_bombgrp&view=personnel&id=4475&Itemid=334 |title = 100th Bomb Group Foundation – Personnel – LT COL Robert ROSENTHAL |author=<!--Staff writer(s); no by-line.--> |website=100thbg.com |publisher=100th Bomb Group Foundation |access-date=5 December 2016 |quote=Dec 1, 1944 – Feb 3, 1945 – 418th BS, 100th BG (H) ETOUSAAF (8AF) Squadron Commander, 55 hours, B-17 Air Leader 5 c/m (combat missions) 45 c/hrs (combat hours) '''1 Division Lead (Berlin Feb 3, 1945''', shot down, picked up by Russians and returned to England) Acting Command 4 Wing Leads, Pilot Feb 3, 1945 – BERLIN – MACR #12046, – A/C#44 8379 }}</ref> on 3 February 1945, that is likely to have ended the life of Roland Freisler, the infamous "hanging judge" of the People's Court.
* 1st Lt Bruce Sundlun (1920–2011): Pilot of ''Damn Yankee'' of the 384th Bomb Group was shot down over Belgium on 1 December 1943 and evaded capture until reaching Switzerland 5 May 1944.<ref>Miller, G. Wayne. [http://www.projo.com/extra/2006/sundlun/ "Bruce at 86: A different kind of man"]. {{webarchive |url=https://web.archive.org/web/20110914234931/http://www.projo.com/extra/2006/sundlun/ |date=14 September 2011 }} ''Providence Journal'', 2006. Retrieved 1 October 2011.</ref>

==Specifications (B-17G)==
[[File:Boeing B-17G Flying Fortress.png|thumb|3-view projection of a B-17G, with inset detail showing the "Cheyenne tail" and some major differences with other B-17 variants]]
[[File:B-17G nose.jpg|thumb|B-17G nose guns]]
{{Aircraft specs
|ref= The Encyclopedia of World Aircraft<ref name="Donald" />
|prime units?= imp
<!--
        General characteristics
-->
|genhide=

|crew= 10: <small>Pilot, co-pilot, navigator, bombardier/nose gunner, flight engineer/top turret gunner, radio operator, waist gunners (2), ball turret gunner, tail gunner</small><ref name="Arizona" />
|capacity=
|length m= 22.66
|length ft= 74
|length in= 4
|length note=
|span m= 31.62
|span ft= 103
|span in= 9
|span note=
|height m= 5.82
|height ft= 19
|height in= 1
|height note=
|wing area sqm= 131.92
|wing area sqft= 1,420
|wing area note=
|airfoil= [[Physics:NACA airfoil|NACA 0018]] / NACA 0010
|empty weight kg= 16,391
|empty weight lb= 36,135
|empty weight note=
|gross weight kg= 24,500
|gross weight lb= 54,000
|gross weight note=
|max takeoff weight kg= 29,700
|max takeoff weight lb= 65,500
|max takeoff weight note=
|fuel capacity=
|more general=
* '''Aspect ratio:''' 7.57
<!--
        Powerplant
-->
|eng1 number= 4
|eng1 name= Wright R-1820-97 "Cyclone"
|eng1 type= turbosupercharged radial engines
|eng1 kw= 895
|eng1 hp= 1,200
|eng1 shp=<!-- prop engines -->
|eng1 note=
|power original=
|thrust original=

|prop blade number=3
|prop name=Hamilton-Standard constant-speed propeller
|prop dia ft=<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|perfhide=

|max speed kmh= 462
|max speed mph= 287
|max speed kts= 249
|max speed note=
|cruise speed kmh= 293
|cruise speed mph= 182
|cruise speed kts= 158
|cruise speed note=
|stall speed kmh=
|stall speed mph=
|stall speed kts=
|stall speed note=
|never exceed speed kmh=
|never exceed speed mph=
|never exceed speed kts=
|never exceed speed note=
|minimum control speed kmh=
|minimum control speed mph=
|minimum control speed kts=
|minimum control speed note=
|range km= 3,219
|range miles= 2,000
|range nmi= 1,738
|range note= with {{Nowrap|6,000 lb}} ({{Nowrap|2,700 kg}}) bombload
|combat range km=
|combat range miles=
|combat range nmi=
|combat range note=
|ferry range km=
|ferry range miles=
|ferry range nmi=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling m= 10,850
|ceiling ft= 35,600
|ceiling note=
|climb rate ms= 4.6
|climb rate ftmin= 900
|climb rate note=
|time to altitude=
|lift to drag=
|wing loading kg/m2= 185.7
|wing loading lb/sqft= 38.0
|wing loading note=
|disk loading kg/m2=
|disk loading lb/sqft=
|disk loading note=
|fuel consumption kg/km=
|fuel consumption lb/mi=
|power/mass= 0.089 hp/lb (150 W/kg)
|thrust/weight=

|more performance=
<!--
        Armament
-->
|armament=
* '''Guns:''' 13 × .50 in (12.7 mm) M2 Browning machine guns in 9 positions (2 in the Bendix chin turret, 2 on nose cheeks, 2 staggered waist guns, 2 in upper Sperry turret, 2 in Sperry ball turret in belly, 2 in the tail and one firing upwards from radio compartment behind bomb bay)
* '''Bombs:'''
** '''Short range missions; Internal load only (<400 mi):''' 8,000 lb ({{Nowrap|3,600 kg}})
** '''Long range missions; Internal load only (≈800 mi):''' 4,500 lb ({{Nowrap|2,000 kg}})
** '''Max Internal and External load:''' 17,600 lb ({{Nowrap|7,800 kg}})

|avionics=
|ferry range mi=3,750}}

==Notable appearances in media==
<!-- All content about the aircraft in fictional and gaming use has been moved to Aircraft in fiction, please see WP:AIRPOP -->

=== B-17 in popular culture ===
A Douglas Aircraft B-17 assembly line is featured in the 1944 drama ''An American Romance''.<ref>{{cite web |title=An American Romance (1944) - Filming & production - IMDb | website=[[Social:IMDb|IMDb]] |url=https://m.imdb.com/title/tt0036596/locations/?item=lc0022457}}</ref><ref>{{cite web |title=B-17 assembly line, 1944 | website=[[Company:YouTube|YouTube]] |url=https://www.youtube.com/watch?v=wPW1L9jUGSw |language=en}}</ref> Hollywood featured the B-17 in its period films, such as director Howard Hawks' ''Air Force'' starring John Garfield and ''Twelve O'Clock High'' starring Gregory Peck.<ref name="imdb1" /> Both films were made with the full cooperation of the {{wipe|United States Army Air Forces}} and used USAAF aircraft and (for ''Twelve O'Clock High'') combat footage. In 1964, the latter film was made into a television show of the same name and ran for three years on ABC TV. Footage from ''Twelve O' Clock High'' was also used, along with three restored B-17s, in the 1962 film ''The War Lover''. An early model YB-17 also appeared in the 1938 film ''Test Pilot'' with Clark Gable and Spencer Tracy, and later with Clark Gable in ''Command Decision'' in 1948, in ''Tora! Tora! Tora!'' in 1970, and in ''Memphis Belle'' with Matthew Modine, Eric Stoltz, Billy Zane, and Harry Connick Jr. in 1990. The most famous B-17, the ''Memphis Belle'', toured the U. S. with her crew to reinforce national morale (and to sell war bonds). She was featured in a USAAF documentary, ''Memphis Belle: A Story of a Flying Fortress''.<ref name="imdb2" />

The Flying Fortress has also been featured in artistic works expressing the physical and psychological stress of the combat conditions and the high casualty rates that crews suffered.<ref>Philo, Tom. [http://www.taphilo.com/history/8thaf/8aflosses.shtml "Eighth Air force Combat Losses"]. {{Webarchive|url=https://web.archive.org/web/20100131044149/http://www.taphilo.com/history/8thaf/8aflosses.shtml |date=31 January 2010 }} ''taphilo.com''. Retrieved: 19 May 2012.</ref><ref>Vargas, John. [http://en.allexperts.com/q/Military-History-669/2010/9/WWII-Bomber-Flight-Crews.htm "Question How many bomber flight crews completed their 25 missions to go home?"] {{webarchive|url=https://web.archive.org/web/20120203223503/http://en.allexperts.com/q/Military-History-669/2010/9/WWII-Bomber-Flight-Crews.htm |date=3 February 2012 }} ''allexperts.com'', 9 November 2010.</ref> Works such as ''The Death of the Ball Turret Gunner'' by Randall Jarrell and ''Heavy Metal''{{'}}s section "B-17" depict the nature of these missions. The Ball turret itself has inspired works like Steven Spielberg's ''The Mission''. Artists who served on the bomber units also created paintings and drawings depicting the combat conditions in World War II.<ref>McCormick, Ken. ''Images of War: The Artist's Vision of World War II''. London: Orion Press, 1990. {{ISBN|978-0-517-57065-4}}.</ref><ref>Mitgang, Herbert. [https://www.nytimes.com/1990/11/03/books/books-of-the-times-how-both-sides-artists-saw-world-war-ii.html?pagewanted=all&src=pm "Books of The Times; How Both Sides' Artists Saw World War II" (review).] ''The New York Times'', 3 November 1990. Retrieved 19 May 2012.</ref>

== See also ==
[[File:Pratt-Whitney T-34 B-17 testbed NAN10-50.jpg|thumb|B-17 modified for testing of the XT-34 turboprop. When testing concluded, the aircraft was restored to stock configuration as the "Liberty Belle", but was lost in a post-forced-landing fire near Oswego, Illinois, on 13 June 2011.]]
{{aircontent
| related =
* [[Engineering:Boeing XB-15|Boeing XB-15]]
* [[Engineering:Boeing XB-38 Flying Fortress|Boeing XB-38 Flying Fortress]]
* [[Engineering:Boeing YB-40 Flying Fortress|Boeing YB-40 Flying Fortress]]
* [[Engineering:Boeing C-108 Flying Fortress|Boeing C-108 Flying Fortress]]
| lists =
* [[Engineering:List of bomber aircraft|List of bomber aircraft]]
* [[Engineering:List of aircraft of World War II|List of aircraft of World War II]]
* List of military aircraft of the United States
| see also =
* Air warfare of World War II
* Boeing B-17 Flying Fortress variants
* B-17 Flying Fortress units of the United States Army Air Forces
* Accidents and incidents involving the B-17 Flying Fortress
}}

== Notes ==
{{NoteFoot}}

== References ==
{{Reflist
|refs =
<ref name="Andrews & Morgan p340">Andrews and Morgan 1988, p. 340.</ref>
<ref name="A&K.1">Arakaki and Kuborn 1991, pp. 73–75, 158–59.</ref>
<ref name="A&K.2">Arakaki and Kuborn 1991, pp. 73, 158–59.</ref>

<ref name="Baugher B-17B">Baugher, Joe. [http://www.joebaugher.com/usaf_bombers/b17_4.html "Boeing B-17B Fortress"]. ''Encyclopedia of American Aircraft'', 22 May 2010.</ref>
<ref name="Baugher Squads">Baugher, Joe. [http://www.joebaugher.com/usaf_bombers/b17_squad.html "B-17 Squadron Assignments"]. ''Encyclopedia of American Aircraft'', Last revised 9 August 1999.</ref>
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* Johnsen, Frederick A. [http://www.airforce-magazine.com/MagazineArchive/Pages/2006/October%202006/1006bomber.aspx "The Making of an Iconic Bomber"]. {{Webarchive|url=https://web.archive.org/web/20120219003449/http://www.airforce-magazine.com/MagazineArchive/Pages/2006/October%202006/1006bomber.aspx |date=19 February 2012 }} ''Air Force Magazine'', Volume 89, Issue 10, October 2006. Retrieved: {{Nowrap|14 September}} 2012.
* Knaack, Marcelle Size. ''Encyclopedia of U.S. Air Force Aircraft and Missile Systems: Volume II: Post-World War II Bombers, 1945–1973''. Washington, D.C.: Office of Air Force History, 1988. {{ISBN|0-16-002260-6}}.
*{{cite journal |last1=Ledet|first1=Michel|title=Des avions alliés aux couleurs japonais |journal=Avions: Toute l'Aéronautique et son histoire |date=April 2002 |issue=109 |pages=17–21 |trans-title=Allied Aircraft in Japanese Colors|language=fr |issn=1243-8650}}
*{{cite journal |last1=Ledet|first1=Michel|title=Des avions alliés aux couleurs japonais |journal= Avions: Toute l'Aéronautique et son histoire |date=May 2002 |issue=110 |pages=16–23|language=fr |issn=1243-8650}}
*Listemann, Phil H. ''Allied Wings No. 7, Boeing Fortress Mk. I''. www.raf-in-combat.com, 2009. First edition. {{ISBN|978-2-9532544-2-6}}.
* Maurer, Maurer. ''Aviation in the U.S. Army, 1919–1939''. Washington, D.C.: United States Air Force Historical Research Center, Office of Air Force History, 1987, pp.&nbsp;406–08. {{ISBN|0-912799-38-2}}.
* {{cite book |last=Morison |first=Samuel Eliot |year=1950 |title=Breaking the Bismarcks Barrier |series=History of United States Naval Operations in World War II |volume=6 |publisher=Little Brown and Company |location=Boston |isbn=0-7858-1307-1 |oclc=10310299 |url=https://archive.org/details/isbn_9780785813071}}
* Parker, Dana T. ''Building Victory: Aircraft Manufacturing in the Los Angeles Area in World War II''. Cypress, California, Dana Parker Enterprises, 2013. {{ISBN|978-0-9897906-0-4}}.
* Parshall, Jonathon and Anthony Tulley. ''Shattered Sword: The Untold Story of the Battle of Midway''. Dulles, Virginia: Potomac Books, 2005. {{ISBN|1-57488-923-0}}.
* Ramsey, Winston G. ''The V-Weapons''. London, United Kingdom: ''After The Battle'', Number 6, 1974.
* Roberts, Michael D. ''[https://web.archive.org/web/20080915133000/http://www.history.navy.mil/branches/dictvol2.htm Dictionary of American Naval Aviation Squadrons: Volume 2: The History of VP, VPB, VP(HL) and VP(AM) Squadrons]''. Washington, D.C.: Naval Historical Center, 2000.
* Sakai, Saburo with Martin Caidin and Fred Saito. ''Samurai!''. Annapolis, Maryland: Naval Institute Press, 1996. {{ISBN|978-0-671-56310-3}}.
* Salecker, Gene Eric. ''Fortress Against The Sun: The B-17 Flying Fortress in the Pacific''. Conshohocken, Pennsylvania: Combined Publishing, 2001. {{ISBN|1-58097-049-4}}.
* Serling, Robert J. ''Legend & Legacy: The Story of Boeing and its People''. New York: St. Martin's Press, 1992. {{ISBN|0-312-05890-X}}.
* Shores, Christopher, Brian Cull and Yasuho Izawa. ''Bloody Shambles: Volume One: The Drift to War to The Fall of Singapore''. London: Grub Street, 1992. {{ISBN|0-948817-50-X}}.
* Stitt, Robert M. ''Boeing B-17 Fortress in RAF Coastal Command Service''. Sandomierz, Poland: STRATUS sp.j., 2010 (second edition 2019). {{ISBN|978-83-65281-54-8}}.
* Swanborough, F. G. and Peter M. Bowers. ''United States Military aircraft since 1909''. London: Putnam, 1963. {{OCLC|846651845}}
* Swanborough, Gordon and Peter M. Bowers. ''United States Navy Aircraft since 1911''. London: Putnam, Second edition, 1976. {{ISBN|0-370-10054-9}}.
* Tate, James P. [https://books.google.com/books?id=pZyLTfJFaEgC ''The Army and its Air Corps: Army Policy toward Aviation 1919–1941'']. Maxwell Air Force Base, Alabama: Air University Press, 1998. {{ISBN|1-4289-1257-6}}. Retrieved: {{Nowrap|1 August}} 2008.
* Trescott, Jacqueline. "Smithsonian Panel Backs Transfer of Famed B-17 Bomber." ''{{wipe|The Washington Post}}'' Volume 130, Issue 333, {{Nowrap|3 November}} 2007.
* Weigley, Russell Frank. ''The American Way of War: A History of United States Military Strategy and Policy''. Bloomington, Indiana: Indiana University Press, 1977. {{ISBN|0-253-28029-X}}.
* Wixley, Ken. "Boeing's Battle Wagon: The B-17 Flying Fortress – An Outline History". ''Air Enthusiast'', No. 78, November/December 1998, pp.&nbsp;20–33. Stamford, UK: Key Publishing. {{ISSN|0143-5450}}.
* Wynn, Kenneth G. ''U-boat Operations of the Second World War: Career Histories, U511-UIT25''. Annapolis, MD: Naval Institute Press, 1998. {{ISBN|1-55750-862-3}}.
* Yenne, Bill. ''B-17 at War''. St. Paul, Minnesota: Zenith Imprint, 2006. {{ISBN|0-7603-2522-7}}.
* Yenne, Bill. ''The Story of the Boeing Company''. St. Paul, Minnesota: Zenith Imprint, 2005. {{ISBN|0-7603-2333-X}}.
* {{cite book |last=Zamzow |first = S. L. |title = Ambassador of American Airpower: Major General Robert Olds |publisher=Biblioscholar |year=2012 |isbn= 978-1-28834434-5}}; originally issued as an academic thesis {{OCLC|405724149}}.

== Further reading ==
* Birdsall, Steve. ''The B-17 Flying Fortress''. Dallas, Texas: Morgan Aviation Books, 1965. {{OCLC|752618401}}.
* {{cite journal |last1=Calegari|first1=Robert|title=A vendre: B-17G|journal=Le Fana de l'Aviation |date=December 1976 |issue=85 |pages=34–36 |issn=0757-4169 |language=fr|trans-title=For Sale: B-17G}}
* Davis, Larry. ''B-17 in Action''. Carrollton, Texas: Squadron/Signal Publications, 1984. {{ISBN|0897471520}}.
* Jablonski, Edward. ''Flying Fortress''. New York: Doubleday, 1965. {{ISBN|0385038550}}.
* Johnsen, Frederick A. ''Boeing B-17 Flying Fortress''. Stillwater, Minnesota: Voyageur Press, 2001. {{ISBN|1580070523}}.
* Gansz, David M. ''B-17 Production – Boeing Aircraft: 4 January 1944 – 26 February 1944 B-17G-35 to G-45 42-31932 – 42-32116 and 42-97058 – 42-97407''. New Jersey: First Mountain Belgians, 2020. {{ISBN|978-1734380606}}.
* Gansz, David M. ''B-17 Production – Boeing Aircraft: 26 February 1944 – 25 April 1944 B-17G-50 to G-60 42-102379 – 42-102978''. New Jersey: First Mountain Belgians, 2013. {{ISBN|978-0692365465}}.
* Gansz, David M. ''B-17 Production – Boeing Aircraft: 25 April 1944 – 22 June 1944 B-17G-65 to G-75 43-37509 – 43-38073''. New Jersey: First Mountain Belgians, 2017. {{ISBN|978-0692859841}}.
* Lloyd, Alwyn T. ''B-17 Flying Fortress in Detail and Scale, Vol. 11: Derivatives, Part 2''. Fallbrook, California: Aero Publishers, 1983. {{ISBN|0816850216}}.
* Lloyd, Alwyn T. ''B-17 Flying Fortress in Detail and Scale, Vol. 20: More derivatives, Part 3''. Blue Ridge Summit, Pennsylvania: Tab Books, 1986. {{ISBN|0816850291}}.
* Lloyd, Alwyn T. and Terry D. Moore. ''B-17 Flying Fortress in Detail and Scale, Vol. 1: Production Versions, Part 1''. Fallbrook, California: Aero Publishers, 1981. {{ISBN|0816850127}}.
* O'Leary, Michael. ''Boeing B-17 Flying Fortress (Osprey Production Line to Frontline 2)''. Botley, Oxford, UK: Osprey Publishing, 1999. {{ISBN|1855328143}}.
* {{cite journal |last1=Stitt|first1=Robert M.|last2=Olson|first2=Janice L.|name-list-style=amp |title=Brothers in Arms: A Boeing B-17 Flying Fortress Crew in New Guinea, Part 1|journal=Air Enthusiast |date=July–August 2002 |issue=100 |pages=2–11 |issn=0143-5450}}
* Thompson, Scott A. ''Final Cut: The Post War B-17 Flying Fortress, The Survivors: Revised and Updated Edition''. Highland County, Ohio: Pictorial Histories Publishing Company, 2000. {{ISBN|1575100770}}.
* Wagner, Ray, ''American Combat Planes of the 20th Century'', Reno, Nevada, 2004, Jack Bacon & Company, {{ISBN|0930083172}}.
* Willmott, H.P. ''B-17 Flying Fortress''. London: Bison Books, 1980. {{ISBN|0853684448}}.
* Wisker Thomas J. "Talkback". ''Air Enthusiast'', No. 10, July–September 1979, p.&nbsp;79. {{ISSN|0143-5450}}

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