The iconic bomber of the Second World War, the B-17 flew in every theater, but was most active in the air war over Europe.
In 1933, the US Army Air Force realized that long-range strategic bombing capability would be crucial in any modern war, and the United States, after introducing its revolutionary B-10 design, was falling behind. So a Request for Proposals was issued seeking a new bomber. The Boeing company responded with a large four-engined design known as the XB-15. While the C-105 transport version was adopted in 1937, and the XB-15’s wing design was used by Boeing in its huge Pan-Am Clipper flying boats, the bomber never entered production and remained “experimental”.
The Navy, meanwhile, was working on a larger version of the Martin B-10, dubbed the B-12. This led to a political conflict, as both the Navy and the Army argued that they should be in charge of developing and deploying long-range strategic bombers.
Nevertheless, in August 1934, the Army issued another request for designs, specifying a bomber with at least twice the payload and range of the old B-10—it had to be capable of carrying 2000 pounds of bombs at 250mph and 10,000 feet altitude over a range of 2000 miles. Douglas Aircraft offered a design based on the twin-engine DC-2 passenger airliner. Boeing’s design mated the wings of the XB-15 design to its 247 passenger plane, resulting in the B-17. It was a daring concept: not only were four-engine planes more expensive to build and operate, but they were widely considered to be more difficult to fly. But Boeing responded by scaling down the size of its XB-15/247 airframe while keeping the same engines, thereby increasing the power-to-weight ratio and producing a better-handling design.
The first B-17 prototype flew in July 1935, and was an immediate sensation. On one of its first flights, the new bomber flew 2100 miles nonstop from the Boeing plant in Seattle to Wright airfield in Dayton OH, averaging 238mph—faster than any American fighter of the time. Not only could the B-17 carry 2500 pounds of bombs, but it also bristled with five machine guns to defend against enemy fighters. It quickly became dubbed the “Flying Fortress”. But when the B-17 prototype crashed during a test flight, the Army, worried about the delay this might cause, as well as the Flying Fortress’s expense, ordered production of the twin-engine Douglas B-18 Bolo bomber instead.
But the Army had liked the Boeing design, and ordered a small number anyway just to keep it available, and as it became more and more apparent that the US and Nazi Germany would inevitably have to face each other, the Air Corps continued to demand a long-range strategic bomber, and the underpowered and already-obsolescent B-18 was not up to the job. So in January 1939 Congress approved money to begin producing B-17s.
By the time of the Battle of Britain in 1940, the US had manufactured a total of 38 B-17C models and had sent 20 of them to England as Lend-Lease supplies, where they were evaluated by the RAF. Now sporting a supercharged engine, the speed in the C model had climbed to over 320mph and range expanded to 2800 miles. But the bombers were a disappointment. The B-17 was unpressurized and open to the air, and while the crews wore electrically-heated suits, the machine guns got so cold at altitude that they froze and became inoperable. The plane had insufficient firepower to the rear. There were also issues with the in-flight oxygen mask system and the bombsight, and the plane’s tail structure was weak.
These problems were corrected with the B-17D model, which added a tail gunner, and then the plane was heavily modified with the B-17E model, known irreverently as the “Big Ass”. The tail fin was greatly expanded and strengthened, which helped with stability, and the armament increased to nine machine guns and 4,000 pounds of bombs. When the United States entered the war in 1941, production of the E model was ramped up. The F model followed shortly after—it had expanded to 11 machine guns and had better engines and better armor. But these later models paid a price in performance for their added weight.
The first B-17 raid in Europe was in August 1942 when eighteen B-17Es struck the railroad yards in Rouen, in France. There was no fighter opposition. On January 27, 1943, B-17F bombers based in England made their first attack on Germany, bombing the port at Wilhelmshaven. Subsequent missions, however, flown without fighter escort, highlighted problems with the bomber and also with American strategic doctrine. The Americans and the British had been arguing over bombing strategy since the beginning. The British favored high-altitude night-bombing with incendiaries that would burn out and destroy large areas inside each city: the Americans preferred lower-altitude daylight raids with precision-dropped high explosive bombs that would target and cripple specific factories and manufacturing plants.
But although it had been hoped that the heavy armament on the Flying Fortress would allow it to fend off enemy attackers, the B-17 was not up to this task. Flying in daylight without fighter escort, the Flying Fortresses suffered horrendous losses from Luftwaffe fighters. The Messerschmitts took advantage of the relatively weak forward fire of the B-17F by making head-on attacks. In March 1943 the P-47 Thunderbolt fighter became available and was assigned to escort B-17s to Germany, but they did not have sufficient range to accompany the bombers the entire distance, and losses continued to be heavy. The average lifetime of a B-17 was 14 missions.
But by the end of 1943, the B-17G model had been introduced, which contained two additional machine guns in a chin turret, and with more powerful engines could carry a load of up to 17,000 pounds of bombs. At the same time, the P-51 Mustang arrived in large numbers, and it had the range to escort the bombers all the way to Germany and back. Now, the Americans began bombing the Nazis almost daily. In February 1944, the Americans massed over 3,000 B-17s to carry out a systematic attack on Germany’s aircraft manufacturing ability, targeting plants in Leipzig, Augsburg, Regensburg, Schweinfurt, and Stuttgart. It became known as “The Big Week”.
In the Pacific, meanwhile, the B-17’s were based in Hawaii, the Philippines and Midway, and were heavily used in China and Burma. By the time the US had obtained suitable bomber bases within range of Japan itself, the B-17s were being replaced by the B-29 Superfortress. But the Flying Fortress’s long range made it useful for reconnaissance and antisubmarine patrols, and the Navy also operated the aircraft under the designation PB-1W.
In all, some 12,725 B-17s were produced during the war—8600 of them G models. At its peak, the US was turning out 130 B-17s each week. Today about 100, of various models but mostly B-17G, still survive. Of these, around a dozen are airworthy.
The B-17G “Shoo Shoo Shoo Baby” flew 24 missions with the 91st Bomb Group in 1944. On its last mission, over Poland, the airplane developed engine trouble and was forced to land in neutral Sweden, where the crew and the B-17 were interned for the rest of the war. Somehow the plane made its way to France, where it was found in 1968, brought back to the United States, and restored by the US Air Force Museum, where it is now on display.
Another B-17G, “Aluminum Overcast”, was delivered to the Army Air Corps in May 1945—too late to have flown in the war. She was sold as surplus and used as a cargo hauler before being obtained by the Experimental Aircraft Association in 1983, restored, and placed on display.