Boeing B - 17 Flying Fortress The Boeing B - 17 Flying Fortress is a four - engine heavy bomber aircraft developed in the 1930s for the United States Army Air Corps ( USAAC ) . Competing against Douglas and Martin for a contract to build 200 bombers , the Boeing entry outperformed both competitors and exceeded the air corps ' expectations . Although Boeing lost the contract because the prototype crashed , the air corps was so impressed with Boeing ' s design that it ordered 13 more B - 17s for further evaluation . From its introduction in 1938 , the B - 17 Flying Fortress evolved through numerous design advances . The B - 17 was primarily employed by the United States Army Air Forces ( USAAF ) in the daylight precision strategic bombing campaign of World War II against German industrial and military targets . The United States Eighth Air Force , based at many airfields in southern England , and the Fifteenth Air Force , based in Italy , complemented the RAF Bomber Command ' s nighttime area bombing in the Combined Bomber Offensive to help secure air superiority over the cities , factories and battlefields of Western Europe in preparation for the invasion of France in 1944 . The B - 17 also participated to a lesser extent in the War in the Pacific , early in World War II , where it conducted raids against Japanese shipping and airfields . From its pre - war inception , the USAAC ( later , the USAAF ) touted the aircraft as a strategic weapon ; it was a potent , high - flying , long - range bomber that was able to defend itself , and to return home despite extensive battle damage . Its reputation quickly took on mythic proportions , and widely circulated stories and photos of notable numbers and examples of B - 17s surviving battle damage increased its iconic status . With a service ceiling greater than any of its Allied contemporaries , the B - 17 established itself as an effective weapons system , dropping more bombs than any other U . S . aircraft in World War II . Of the of bombs dropped on Germany and its occupied territories by U . S . aircraft , 640 , 000 tonnes were dropped from B - 17s . As of May 2015 , 10 aircraft remain airworthy . None of them are combat veterans . Additionally , a few dozen more are in storage or on static display . The oldest is a D - series combat veteran with service in the Pacific and the Caribbean . Development . Origins . On 8 August 1934 , the U . S . Army Air Corps ( USAAC ) tendered a proposal for a multi - engine bomber to replace the Martin B - 10 . The air corps was looking for a bomber capable of reinforcing the air forces in Hawaii , Panama , and Alaska . Requirements were that it would carry a " useful bombload " at an altitude of for 10 hours with a top speed of at least . They also desired , but did not require , a range of and a speed of . The competition for the air corps contract would be decided by a " fly - off " between Boeing ' s design , the Douglas DB - 1 , and the Martin Model 146 at 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 . It combined features of the experimental Boeing XB - 15 bomber with the Boeing 247 transport aircraft . The B - 17 ' s armament consisted of up to of bombs on two racks in the bomb bay behind the cockpit , and initially possessed five machine gun s . It was powered by four Pratt & Whitney R - 1690 " Hornet " radial engines each producing at . The first flight of the Model 299 was on 1935 with Boeing chief test - pilot Leslie Tower at the controls . Richard Williams , a reporter for the " $ 3 " , coined the name " Flying Fortress " when the Model 299 was rolled out bristling with multiple machine gun installations . The most unusual gun emplacement was the nose installation ( see note for description and drawing ) , which allowed the single machine gun to be fired toward almost any frontal angle that an approaching enemy fighter could take to attack the B - 17 . Boeing was quick to see the value of the name and had it trademarked for use . 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 . On , the prototype flew from Seattle to Wright Field in nine hours and three minutes at an average cruising speed of , much faster than the competition . At the fly - off , the four - engine Boeing ' s performance was superior to those of the twin - engine DB - 1 and Model 146 . Then - Major General Frank Maxwell Andrews of the GHQ Air Force believed that the long - range capabilities of four - engine large aircraft were more effective than shorter - ranged , twin - engine aircraft , and that the B - 17 was better suited to their doctrine . His opinions were shared by the air corps procurement officers , and even before the competition had finished they suggested buying 65 B - 17s . Development continued on the Boeing Model 299 , and on 1935 , army air corps test - pilot Major Ployer Peter Hill and Boeing employee Les Tower took the Model 299 on a second evaluation flight . The crew forgot to disengage the " gust lock s " , a system of devices integral to the design that held the bomber ' s movable control surfaces in place while the aircraft was parked on the ground . After take - off , due to the failure to manually disengage all of the gust locks , the aircraft entered a steep climb , stalled , nosed over , and crashed , killing Hill and Tower ( other observers survived with injuries ) . The crashed Model 299 could not finish the evaluation and , while the air corps was still enthusiastic about the aircraft ' s potential , army officials were daunted by the much greater expense per aircraft ( Douglas quoted a unit price of $ 58 , 200 based on a production order of 220 aircraft , compared with a price of $ 99 , 620 from Boeing ) , and as the competition could not be completed Boeing was legally disqualified from the consideration for the contract . Army Chief of Staff Malin Craig cancelled the order for 65 YB - 17s , and ordered 133 of the twin - engine Douglas B - 18 Bolo instead . Initial orders . Regardless , the USAAC had been impressed by the prototype ' s performance , and on 1936 , through a legal loophole , the air corps ordered 13 YB - 17s ( designated Y1B - 17 after November 1936 to denote its special F - 1 funding ) for service testing . The YB - 17 incorporated a number of significant changes from the Model 299 , including more powerful Wright R - 1820 - 39 Cyclone engines replacing the original Pratt & Whitneys . 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 ) , the term " XB - 17 " was retroactively applied to the 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 . One suggestion adopted was the use of a pre - flight checklist to avoid accidents such as that which befell the Model 299 . 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 " off the Atlantic coast . The mission was successful and widely publicized . The 13th Y1B - 17 was delivered to the Material Division at Wright Field , Ohio , to be used for flight testing . A 14th Y1B - 17 ( " 37 - 369 " ) , originally constructed for ground testing of the airframe ' s strength , was upgraded and fitted with exhaust - driven turbochargers . Scheduled to fly in 1937 , it encountered problems with the turbochargers , and its first flight was delayed until 1938 . The aircraft was delivered to the army on 1939 . 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 . 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 . Improved with larger flaps , rudder and a well - framed plexiglas 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 ; however , prior to the attack on Pearl Harbor , fewer than 200 B - 17s were in service with the army . A total of 155 B - 17s of all variants were delivered between 1937 and 1941 , but production quickly accelerated , with the B - 17 eventually setting the record for achieving the highest production rate for large aircraft . The aircraft went on to serve in every World War II combat zone , and by the time production ended in May 1945 , 12 , 731 aircraft had been built by Boeing , Douglas and Vega ( a subsidiary of Lockheed ) . Design and variants . 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 of Langley Field , Virginia , to develop heavy bombing techniques , and the 13th was used for flight testing at the Material Division at Wright Field , Ohio . Experiments on this aircraft led to the use of a quartet of turbo - superchargers which would become standard on the B - 17 line . A 14th aircraft , the YB - 17A , originally destined for ground testing only and upgraded with the turbochargers , was re - designated B - 17A after testing had finished . 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 rudders and flaps . The B - 17C changed from three bulged , oval shaped machine gun blisters to two flush , oval - shaped machine gun window openings and a single " bathtub " machine gun housing on the lower fuselage , that resembled the similarly configured and located ventral defensive emplacement on the German Heinkel He 111 P - series medium bomber . Models " A " through " D " of the B - 17 were designed defensively , while the large - tailed B - 17E was the first model primarily focused on offensive warfare . The B - 17E was an extensive revision of the Model 299 design : The fuselage was extended by ; a much larger rear fuselage , vertical tail fin , rudder , and horizontal stabilizer were added to the design ; a gunner ' s position was added in the new tail ; the nose ( especially the bombardier ' s well - framed nose glazing ) remained relatively the same as the earlier " B " through " D " versions had , but with the addition of a Sperry electrically powered manned dorsal gun turret just behind the cockpit , and the similarly powered ( also built by Sperry ) manned ventral ball turret just aft of the bomb bay – replacing a relatively hard - to - use , Bendix - designed remotely operated ventral turret on the earliest examples of the " E " variant , that had also been used on the earlier marks of the North American B - 25 Mitchell – resulted in a 20 % increase in aircraft weight . The B - 17 ' s turbocharged Wright R - 1820 Cyclone 9 engines were upgraded to increasingly more powerful versions of the same powerplants multiple times throughout its production , and similarly , the number of machine gun emplacement locations were increased to enhance their aircraft ' s combat effectiveness . The B - 17F variants were the primary versions flying for the Eighth Air Force to face the Germans in 1943 , and had standardized the manned Sperry ball turret for ventral defense , along 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 type was abandoned , the V - 1710 being kept for fighters . The YB - 40 was a heavily armed modification of the standard B - 17 used before the 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 " and twin 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 heavier than a fully loaded B - 17F . The YB - 40s with their numerous heavy modifications had trouble keeping up with the lighter bombers once they had dropped their bombs , and so the project was abandoned and finally phased out in July 1943 , but not before the final production blocks of the B - 17F from Douglas ' plants adopted the YB - 40 ' s remotely operated and fired Bendix " chin turret " for a much - improved forward defensive weapons installation . By the time the definitive B - 17G appeared , the number of guns had been increased from seven to thirteen , 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 , adopting the remotely operated " chin turret " for forward defense from the YB - 40 " gunship " version , and in total 8 , 680 were built , the last one ( by Lockheed ) on 1945 . Many B - 17Gs were converted for other missions such as cargo hauling , engine testing and reconnaissance . Initially designated SB - 17G , a number of B - 17Gs were also converted for search - and - rescue duties , later to be redesignated B - 17H . Late in World War II , at least 25 B - 17s were fitted with radio controls and television cameras , loaded with of high - explosives and dubbed BQ - 7 " Aphrodite missiles " for Operation Aphrodite . The operation , which involved remotely flying Aphrodite drones onto their targets by accompanying CQ - 17 " mothership " control aircraft , was approved on 1944 , and assigned to the 388th Bombardment Group stationed at RAF Fersfield , a satellite of RAF Knettishall . The first four drones were sent to Mimoyecques , the Siracourt V - 1 bunker , Watten and Wizernes on 4 August , causing little damage . The project came to a sudden end with the unexplained mid - air explosion over the Blyth estuary of a B - 24 , part of the United States Navy ' s contribution as " Project Anvil " , en route for Heligoland piloted by Lieutenant Joseph P . Kennedy Jr . , future U . S . president John F . Kennedy ' s elder brother . Blast damage was caused over a radius of . British authorities were anxious that no similar accidents should again occur , and the Aphrodite project was scrapped in early 1945 . Operational history . The B - 17 began operations in World War II with the Royal Air Force ( RAF ) in 1941 ( but was not successful ) , 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 . A squadron of B - 17 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 . After the defeat in Java , the 19th withdrew to Australia where it continued in combat until it was sent back home by General George C . Kenney when he arrived in Australia in mid - 1942 . 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 . 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 . Early models proved to be unsuitable for combat use over Europe and it was the B - 17E that was first successfully used by the USAAF . The defense expected from bombers operating in close formation alone did not prove effective and the bombers needed fighter escorts to operate successfully . During World War II , the B - 17 equipped 32 overseas combat groups , inventory peaking in August 1944 at 4 , 574 USAAF aircraft worldwide . B - 17s dropped of bombs on European targets ( compared to dropped by the Liberator and dropped by all other U . S . aircraft ) . The British heavy bombers , the Avro Lancaster and Handley Page Halifax , dropped 608 , 612 long tons ( 681 , 645 short tons ) and 224 , 207 long tons ( 251 , 112 short tons ) respectively . RAF use . The Royal Air Force entered World War II with no heavy bomber of its own in service ; the biggest available were long - range medium bombers such as the Vickers Wellington which could carry up to of bombs . While the Short Stirling and Handley Page Halifax would become its primary bombers by 1941 , in early 1940 the RAF entered into an agreement with the U . S . Army Air Corps to be provided with 20 B - 17Cs , which were given the service name Fortress I . Their first operation , against Wilhelmshaven on 1941 was unsuccessful ; on , the target was Brest , France , but again the bombers missed completely . By September , after the RAF had lost eight B - 17Cs in combat or to accidents and many instances of aborts due to mechanical problems , 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 . As usage by Bomber Command had been curtailed , the RAF transferred its remaining Fortress I aircraft to Coastal Command for use as a long - range maritime patrol aircraft instead . These were later augmented in August 1942 by 19 Fortress Mk II ( B - 17F ) and 45 Fortress Mk IIA ( B - 17E ) . A Fortress from No . 206 Squadron RAF sank U - 627 on 1942 , the first of 11 U - boat kills credited to RAF Fortress bombers during the war . The RAF ' s No . 223 Squadron , as part of 100 Group , operated a number of Fortresses equipped with an electronic warfare system known as " Airborne Cigar " ( ABC ) . This was operated by German – speaking radio operators who would identify and jam German ground controllers ' broadcasts to their nightfighter s . They could also pose as ground controllers themselves with the intention of steering nightfighters away from the bomber stream s . Initial USAAF operations over Europe . The air corps ( renamed United States Army Air Forces ( USAAF ) on 20 June 1941 ) , using the B - 17 and other bombers , bombed from high altitudes using the then - secret Norden bombsight , known as the " Blue Ox " , which was an optical electro - mechanical gyro - stabilized analog computer . The device was able to determine , from variables input 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 . 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 1942 , to form the 97th Bomb Group . On 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 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 . The operation , carried out in good visibility , was a success , with only minor damage unrelated to the enemy to one aircraft and half the bombs landing in the target area . The raid helped assuage British doubts about the capabilities of American heavy bombers in operations over Europe . Two additional groups arrived in England at the same time , bringing with them the first B - 17Fs , which would serve 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 ) , such that unescorted bombing missions came to be discouraged . 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 " would weaken the " Wehrmacht " , destroy German morale and establish air superiority through Operation Pointblank ' s destruction of German fighter strength in preparation of a ground offensive . The USAAF bombers would attack by day , with British operations – chiefly against industrial cities – by night . 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 . Attacks began in April 1943 on heavily fortified key industrial plants in Bremen and Recklinghausen . 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 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 . A second attempt on Schweinfurt on 14 October 1943 would later come to be known as " Black Thursday " . 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 . 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 – a total loss of 77 B - 17s . A total of 122 bombers were damaged and needed repairs before their next flight . Out of 2 , 900 men in the crews , about 650 men did not return , although some survived as prisoners of war . Only 33 bombers landed without damage . These losses were a result of concentrated attacks by over 300 German fighters . Such high losses of air crews 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 night fighting ability noticeably improved to counter the nighttime strikes , challenging the conventional faith in the cover of darkness . The Eighth Air Force alone lost 176 bombers in October 1943 , and was to suffer similar casualties on 1944 on missions to Oschersleben , Halberstadt and Brunswick . Lieutenant General James Doolittle , commander of the Eighth , 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 . A third raid on Schweinfurt on 1944 highlighted what came to be known as " Big Week " , during which the bombing missions were directed against German aircraft production . German fighters would have to respond , and the North American P - 51 Mustang and Republic P - 47 Thunderbolt fighters ( equipped with improved drop tanks to extend their range ) accompanying the American heavies all the way to and from the targets would engage them . The escort fighters reduced the loss rate to below seven percent , with only 247 B - 17s lost in 3 , 500 sortie s while taking part in the Big Week raids . By September 1944 , 27 of the 42 bomb groups of the Eighth Air Force and six of the 21 groups of the Fifteenth Air Force used B - 17s . Losses to flak continued to take a high toll of heavy bombers through 1944 , but by 1945 ( two 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 . Pacific Theater . 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 , were flown into Pearl Harbor from Hamilton Field , California , arriving during the attack on Pearl Harbor . 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 . Enemy activity forced an abort from Hickam Field to Bellows Field , where the aircraft overran the runway and 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 . By 1941 , the Far East Air Force ( FEAF ) based at Clark Field in the Philippines had 35 B - 17s , with the War Department eventually planning to raise that to 165 . 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 air fields in Formosa , in accordance with Rainbow 5 war plan directives , but this was overruled by General Douglas MacArthur . 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 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 , and was all but destroyed over the next few days . Another early World War II Pacific engagement on 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 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 . Noted Japanese ace Saburo Sakai is credited with this kill , and in the process , came to respect the ability of the Fortress to absorb punishment . B - 17s were used in early battles of the Pacific with little success , notably the Battle of Coral Sea and Battle of Midway . While there , the Fifth Air Force B - 17s were tasked with disrupting the Japanese sea lanes . Air Corps doctrine dictated bombing runs from high altitude , but it was soon discovered that only one percent of their bombs hit targets . However , B - 17s were operating at heights too great for most A6M Zero fighters to reach , and the B - 17 ' s heavy gun armament was more than a match for lightly protected Japanese aircraft . On 2 March 1943 , six B - 17s of the 64th Squadron attacked a major Japanese troop convoy from during the early stages of the Battle of the Bismarck Sea , off New Guinea , using skip bombing to sink three merchant ships including the . A B - 17 was shot down by a New Britain - based A6M Zero , whose pilot then machine - gunned some of the B - 17 crew members as they descended in parachutes and attacked others in the water after they landed . Later , 13 B - 17s bombed the convoy from medium altitude , causing the ships to disperse and prolonging the journey . The convoy was subsequently all but destroyed by a combination of low level strafing runs by Royal Australian Air Force Beaufighters , and skip bombing by USAAF North American B - 25 Mitchell s at , while B - 17s claimed five hits from higher altitudes . A peak of 168 B - 17 bombers were in the Pacific theater in September 1942 , with all groups converting to other types by mid - 1943 . In mid - 1942 , Gen . Arnold decided that the B - 17 was inadequate 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 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 . 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 . Bomber defense . Before the advent of long - range fighter escorts , B - 17s had only their . 50 caliber M2 Browning machine gun s 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 . The number of defensive guns increased from four machine guns and one nose machine gun in the B - 17C , to thirteen 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 . 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 . To address this problem , the United States developed the bomb - group formation , which evolved into the staggered combat box formation where all the B - 17s could safely cover any others in their formation with their machine guns , making a formation of the bombers a dangerous target to engage by enemy fighters . " Luftwaffe " fighter pilots likened attacking a B - 17 combat box formation to encountering a " fliegendes Stachelschwein " , " flying porcupine " , with dozens of machine guns on a combat box formation of bombers , 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 the German flak . Moreover , German fighter aircraft later used the tactic of high - speed strafing passes rather than engaging with individual aircraft to inflict damage with minimum risk . As a result , the B - 17s ' loss rate was up to 25 % on some early missions ( 60 of 291 B - 17s were lost in combat on the second Raid on Schweinfurt ) , and it was not until the advent of long - range fighter escorts ( particularly the North American P - 51 Mustang ) resulting in the degradation of the " Luftwaffe " as an effective interceptor force between February and June 1944 , that the B - 17 became strategically potent . The B - 17 was noted for its ability to absorb battle damage , still reach its target and bring its crew home safely . Wally Hoffman , a B - 17 pilot with the Eighth Air Force during World War II , said , " The plane can be cut and slashed almost to pieces by enemy fire and bring its crew home . " Martin Caidin reported one instance in which a B - 17 suffered a mid - air collision with a 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 . Its toughness was compensation for its shorter range and lighter bomb load compared to the B - 24 and British Avro Lancaster heavy bombers . Stories abound of B - 17s returning to base with tails having been destroyed , with only a single engine functioning or even with large portions of wings having been damaged by flak . 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 . The B - 17 design went through eight major changes over the course of its production , culminating in the B - 17G , differing from its immediate predecessor by the addition of a bombardier - operated , remotely controlled chin turret with two caliber M2 Browning machine gun s under the nose , also fitted to the final eighty - six production aircraft of the B - 17F - DLs built by Douglas , after being first tried in May 1943 as part of the increased armament system of the YB - 40 . This eliminated the B - 17 ' s main defensive weakness in head - on attacks . Luftwaffe attacks . After examining wrecked B - 17s and B - 24s , Luftwaffe officers discovered that on average it took around 20 hits with 20 mm shells fired from the rear to bring them down . 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 rounds at a bomber . Early versions of the Fw 190 , one of the best German interceptor fighters , were equipped with two MG FF cannons , which carried only 500 rounds when belt - fed ( normally using 60 - round drum magazine s in earlier installations ) , and later with the better 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 13 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 . To address 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 — as ordered by the Eighth Air Force ' s commander , then - Maj . Gen . Jimmy Doolittle — to clear any Luftwaffe defensive fighters from the skies . By 1944 , a further upgrade to Rheinmetall - Borsig ' s 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 . The adoption of the 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 – 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 Bf 110 daylight " Zerstörer " aircraft . However , due to the slow 715 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 . The Luftwaffe also fitted heavy - calibre " Bordkanone " - series 37 , 50 and even cannon as anti - bomber weapons on twin - engine aircraft such as the special Ju 88P fighters , as well as one model of the Me 410 " Hornisse " but these measures did not have much effect on the American strategic bomber offensive . The Me 262 , however , had moderate success against the B - 17 late in the war . With its usual nose - mounted armament of four 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 ' defensive guns and bring an aircraft down with one hit , as both the MK 108 ' s shells and the R4M ' s warheads were filled with the " shattering " force of the strongly brisant Hexogen military explosive . Luftwaffe - captured B - 17s . During World War II , after crash - landing or being forced down , approximately 40 B - 17s were captured and refurbished , with about a dozen put back into the air . Given German " Balkenkreuz " national markings on their wings and fuselage sides , and " " Hakenkreuz " 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 . 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 . 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 Valencia airfield , 1944 , remaining there for the rest of the war . 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 . 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 . 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 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 division , but they never saw combat . In 1946 the regiment was assigned to the Kazan factory to aid in the Soviet effort to reproduce the more advanced Boeing B - 29 as the Tupolev Tu - 4 . Swiss - interned B - 17s . During the war , the Allied bomber offensive sometimes took U . S . or British bombers into Swiss airspace , either damaged craft seeking safe haven or on rare occasions bombing Swiss cities by accident . Swiss aircraft would attempt 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 . From then on , red and white neutrality bands were added to the wings of Swiss aircraft to stop accidental attacks by Allied aircraft . 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 . One prime example : in October 1943 the Swiss interned Boeing B - 17F - 25 - VE , tail number 25841 , and her U . S . flight crew after the Flying Fortress developed engine trouble and was forced to land following its bombing raid over Germany . The aircraft was then turned over to the Swiss Air Force , who then flew the bomber until the end of the war , using other interned but non - flyable B - 17s for spare parts . The bomber was repainted a dark olive drab , but retained its light gray - painted under surfaces . It carried Swiss national white cross insignia in red squares on both sides of its rudder , fuselage sides , and the underside wings , with white crosses in red roundel s atop both upper wings . As on its gray under surfaces , the B - 17F also carried light gray flash letters " RD " and " I " on either side of the Swiss national insignia . Japanese - captured B - 17s . Three damaged B - 17s , one " D " model and two " E " models , were rebuilt to flying status by Japanese technicians and mechanics ; the parts used were stripped from captured B - 17 wrecks in both the Philippines and the Netherlands East Indies . The three bombers , containing captured top secret Norden Bombsight s , were then flown to Japan where they underwent extensive technical evaluation by the Imperial Japanese Army Air Force ' s Air Technical Research Laboratory ( Koku Gijutsu Kenkyujo ) . The " D " model was later deemed an obsolete design and the two " E " models were used to develop B - 17 air combat counter - tactics ; they were also used as enemy aircraft in several Japanese propaganda films . No traces of these captured Flying Fortresses were found in Japan by Allied occupation forces following the war ; they were assumed scrapped late in the war for their vital war materials . Postwar history . U . S . Air Force . Following the end of 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 significant numbers remained in use in second - line roles such as VIP transports , air - sea rescue and photo - reconnaissance . Strategic Air Command ( SAC ) , established in 1946 , used reconnaissance B - 17s ( at first called F - 9 [ " F " for " Fotorecon " ] , later RB - 17 ) until 1949 . With the disestablishment of the U . S . Army Air Forces and the establishment of an independent U . S . Air Force in 1947 , most extant B - 17s were transferred to USAF . 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 lifeboat s had begun in 1943 , but they entered service in the European theater only in February 1945 , also being used to provide search and rescue support for 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 . In 1946 , surplus B - 17s were chosen as drone aircraft for atmospheric sampling during the Operation Crossroads atomic bomb tests , being able to fly close to or even through the 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 surface - to - air and air - to - air missile s . were converted to drones . The last operational mission flown by a USAF Fortress was conducted on 1959 , when a DB - 17P , serial " 44 - 83684 " directed a QB - 17G , out of Holloman Air Force Base , New Mexico , as a target for an AIM - 4 Falcon air - to - air missile fired from an McDonnell F - 101 Voodoo . A retirement ceremony was held several days later at Holloman AFB , after which " 44 - 83684 " was retired . 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 . Perhaps the most famous B - 17 , the " Memphis Belle " , is currently being fastidiously restored — simultaneously with the B - 17D " The Swoose " — to its World War II wartime appearance by the National Museum of the United States Air Force at Wright - Patterson Air Force Base , Ohio . U . S . Navy and U . S . Coast Guard . During the last year of World War II and shortly thereafter , the United States Navy 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 . 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 . Thirty - two B - 17Gs 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 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 deleted . These aircraft were painted dark blue , a standard Navy paint scheme which had been adopted in late 1944 . The PB - 1W eventually evolved into an early warning aircraft by virtue of its APS - 20 search radar . 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 USN in 1962 ) , a military version of the Lockheed 1049 Constellation commercial airliner . 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 . 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 . They were used primarily for air - sea rescue , but were also used for iceberg patrol duties and for photo mapping . Air - sea rescue PB - 1Gs usually carried a droppable lifeboat underneath the fuselage and the chin turret was often replaced by a radome . The Coast Guard PB - 1Gs served throughout the 1950s , the last example not being withdrawn from service until 14 October 1959 . Special operations . A number of 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 . 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 . 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 , is on display in the Evergreen Aviation & Space Museum in McMinnville , Oregon . Operators . The B - 17 was a versatile aircraft , serving in dozens of USAAF units in theaters of combat throughout World War II , and in non - bomber roles for the RAF . Its main use was in Europe , where its shorter range and smaller bombload relative to other aircraft available did not hamper it as much as in the Pacific Theater . Peak USAAF inventory ( in August 1944 ) was 4 , 574 worldwide . Fortresses as a symbol . The B - 17 Flying Fortress has become , for many reasons , an icon of American power and a symbol of its Air Force . During the 1930s , the USAAC , as articulated by then - Major General Frank Maxwell Andrews and the Air Corps Tactical School , touted the bomber as a strategic weapon . General Henry H . Arnold , Chief of the Air Corps , recommended the development of bigger aircraft with better performance , and the Tactical School agreed . When the Model 299 was rolled out on 1935 , bristling with multiple machine gun installations , Richard Williams , a reporter for " The Seattle Times " coined the name " Flying Fortress " with his comment , " Why , it ' s a flying fortress ! " Boeing was quick to see the value of the name and had it trademarked for use . In 1943 , Consolidated Aircraft commissioned a poll to see " to what degree the public is familiar with the names of the Liberator and the Flying Fortress . " Of 2 , 500 men in cities where Consolidated adverts had been run in newspapers , 73 % had heard of the B - 24 , while 90 % knew of the B - 17 . After the initial B - 17s were delivered to the Air Corps 2nd Bombardment Group , they were used on promotional flights emphasizing their great range and navigational precision . In January 1938 , group commander Colonel Robert Olds flew a YB - 17 from the east to 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 in 11 hours 1 minute . Six bombers of the 2nd Bombardment Group took off from Langley Field on 1938 as part of a goodwill flight to Buenos Aires , Argentina . Covering they returned on , with seven aircraft setting off on a flight to Rio de Janeiro , Brazil , three days later . In a well - publicized mission on 12 May of the same year , three B - 17s " intercepted " and took photographs of the Italian ocean liner SS " Rex " off the Atlantic coast . Many pilots who flew both preferred the B - 17 over the B - 24 for its greater stability and ease in formation flying . Its electrical systems were less vulnerable to damage than the B - 24 ' s hydraulics , and the B - 17 flew better than the B - 24 when missing an engine . 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 studies showed that Fortresses had utility and survivability much greater than that of the B - 24 . Making it back to base on numerous occasions despite extensive battle damage , its durability became mythical ; stories and photos of B - 17s surviving battle damage were widely circulated during the war . Despite an inferior performance and smaller bombload than the more numerous B - 24 , a survey of Eighth Air Force crews showed a much higher rate of satisfaction in the B - 17 . Noted B - 17 pilots and crew members . 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 : B - 17 in popular culture . 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 . Both films were made with the full cooperation of the 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 " . The B - 17 also appeared in the 1938 movie " Test Pilot " with Clark Gable and Spencer Tracy , 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 its crew to reinforce national morale ( and to sell war bond s ) . It starred in a USAAF documentary , " " . The B - 17 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 . Works such as The Death of the Ball Turret Gunner by Randall Jarrell and Heavy Metal ( film ) ' 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 .