The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps. The B-17 was primarily employed by the USAF in the daylight strategic bombing campaign of World War II against German industrial and military targets.
The United States 8th Air Force, based at many airfields in central and southern England, and the 15th Air Force based in Italy, complemented the RAF Bomber commands 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 2, where it conducted raids against Japanese shipping and airfields.
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 expensive bombload. It developed a reputation for toughness based upon stories and photos of badly damaged B-17 safely returning to base. The B-17 dropped more bombs than any other US aircraft in World War II. Of the 1.5 million tons of bombs dropped on Nazi Germany and its occupied territories by US aircraft. Six hundred forty thousand tons were dropped from B-17’s.
The first flight of the model 299, was on the 28th of July 1935, with Boeing chief test pilot Leslie Tower at the controls. 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 airplane. Boeing was quick to see the value of the name and had it trademarked for use.
At the time of the attack on Pearl Harbor fewer than 200 were in service with the army air forces.
B 17’s in Europe
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 the German Luftwaffe. In preparation for the invasion of France B-17 and B-25 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 a new model, the B-17 II was first successfully used by the USAAF.
The B-17’s 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 some 32 overseas combat groups
In early 1940, the RAF entered into an agreement with the U.S. Army Air Corps to acquire 20 B-17 C’s, which were given the service name Fortress I, their first operation against Wilhelmshaven on the 8th of July 1941, was unsuccessful. On the 24th of July 3, B-17’s of 90 squadron took part in a raid on the German capital ships Gneisenau and Prinz Eugen anchored in Brest from 30,000 feet with the objective of drawing German fighters away from 18 Hampton Bombers attacking at lower altitudes and in time 479 Vickers Wellington to attack later while the German fighters were refueling. The operation did not work as expected, with 90 squadrons Fortresses being unopposed.
By September the RAF had lost 8 B-17C’s 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 defences, larger bomb loads and more accurate bombing methods were required. However, the USAF continued using the B-17 as a day bomber, despite misgivings by the RAF that attempts at daylight bombing would be ineffective, as used by Bomber Command had been curtailed. The RAF transferred its remaining fortress’s to coastal command for use as a long-range maritime patrol aircraft. These were later augmented in August 1942 by B-17F’s. On the 27th of October 1942, the first of eleven u-boat kills credited to RAF fortress bombers during the war was made. The RAF’s number 223 squadron as part of 100 group, operated a number of fortresses equipped with an electronic warfare system known as airborne cigar. This was operated by German speaking radio operators, who were to identify and jam German ground controllers broadcasts to their night fighters. They could also pose as ground controllers themselves, with the intention of steering night fighters away from the bomber streams topic.
USAAF B-17’s in Europe
Initial USAAF operations over Europe, the Air Corps, renamed United States Army Air Forces or USAAF on the 20th of 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, which was an Optical electromechanical, gyro-stabilized analog computer, 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 the USAAF began, building up its Air Forces in Europe using B-17.
The first 8th air force units arrived in England on the 12th of May 1942 to form the 97th Bomb Group. On the 17th of August 1942, 12 B-17s of the 97th, with the lead aircraft piloted by Major Paul Tibbets and carrying Brigadier General Ira Eaker as an observer were escorted by four squadrons of RAF Spitfire’s and a further five squadrons of Spitfire to cover the withdrawal on the first USAAF heavy bomber raid over Europe against the large railroad marshalling yards at Rouen, 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 to one aircraft unrelated to enemy, action and half the bombs landing in the target area. The raid help delay 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-17F’s, 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 the 13th of June 1943 such that further raids at the time were discouraged. German fighter aircraft later developed the tactic of high-speed strafing passes, rather than engaging with individual aircraft to inflict damage with minimum risk. As a result, the B17s loss rate was up to 25 percent on some early missions.
After the American and British bomber commands were organized at the Casablanca Conference in January 1943. The resulting combined bomber offensive was designed to weaken the Luftwaffe and destroyed German morale. The USAAF bombers, attacked by day with British operations chiefly against industrial cities by night operations. General Ira Eaker and the 8th Air Force placed the 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 on Bremen. 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 the war effort there. The first raid on the 17th of August 1943 did not result in critical damage to the factories, with the 230 attacking B-17’s 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 was lost that day.
A second attempt on Schweinfurt on the 14th of october 1943 later came to be known as Black Thursday, while the attack was successful at disrupting the entire works severely curtailing work, therefore, the remainder of the war. It was at an extreme cost of the 291 attacking fortresses. Sixty were shot down over Germany. Five crashed on approach to Britain and twelve more were scrapped due to damage a loss of 77 b-17s. Additionally, 122 bombers were damaged and needed repairs before their next flights. Only 33 bombers landed without damage. These losses were a result of concentrated attacks by over 300 German fighters.
Such high losses of aircrews could not be sustained. The USAAF recognizing the vulnerability of heavy bombers to fighter interceptors when operating alone and 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 8th Air Force alone lost 176 bombers in October 1943 and was to suffer similar casualties on the 11th of January 1944, on missions to Germany. Lieutenant General James Doolittle, commander of the 8th, ordered the 2nd Schweinfurt mission to be cancelled as the weather deteriorated, but the lead units had already entered hostile airspace 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 the 24th of February 1944 highlighted what came to be known as the big week, during which the bombing missions were directed against German aircraft production, German fighters needed to respond and the North American P-51 Mustang and Republic P-47 Thunderbolt fighters equipped with drop tanks to extend their range accompanying the American heavies all the way to and from the targets engaged them. The escort fighters reduced the loss rate to below 7 %, with only 247 B-17s lost in 3,500 sorties, while taking part in the big week raids by September 1944, 27 of the 42 Bomb groups of the 8th Air Force and 6 of the 21 groups of 15th Air Force had B-17 losses. 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 the 27th of April 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.
It was not until the advent of long-range fighter escorts particularly the 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. The B-17 was noted for its ability to absorb battle damage and still reach its target and bring its crew home safely.
Other factors, such as combat effectiveness and political issues, also contributed to the B-17 success.
The B-17 Flying Fortress became symbolic in the United States of that country’s air power. Many B-17 crew members received military honors and 17 received the Medal of Honor the highest military decoration awarded by the United States.