One of the United States' two standard heavy bombers until the introduction of the B-29 Superfortress, the B-17 was flown by the United States Army Air Force throughout the American participation in the Second World War. Wing to wing with B-24 Liberators , B-17s were used by the US Eighth Air Force based in the UK, to bombard German targets in Europe during daylight hours a method which resulted initially in very heavy losses.

The Flying Fortress was designed for a competition, announced in 1934, to find a modern replacement for the assorted Keystone biplane bombers then in service. The prototype first flew on 28 July 1935, and went on to win the competition. Boeing then built a few pre-production YlB-17s (later re-designated B-17As), followed by 39 B-17Bs which entered service in the late thirties. Money was short, and by the autumn of 1939 only 30 Flying Fortresses were fully operational. As the US was not then fighting in Europe it did not seem to matter although, as it became clearer that involvement was inevitable, orders were increased. Furthermore, a small number of B-17Cs delivered to the RAF as Fortress Is quickly showed that defensive armament was inadequate.

In September of 1941, a new Fortress appeared with an extensively modified empennage. Gone was the pert fin and rudder riding precariously behind the stabilizer. Instead, a broad yet graceful dorsal fin rose from amidships and enveloped a deadly stinger of twin .50 cal. machine guns. A remote controlled belly turret held two more. 50's. This was the B-17E, of which 112 were built. Four hundred more followed but with a manned Sperry ball turret replacing the remote system. The B-17E was lengthened to 73 feet 10 inches to accommodate the new defensive tail position. Top speed was 317 mph, cruising at over 200 mph with 4,000 pounds of bombs.

The Pearl Harbor attack of 7 December 1941 finally brought the United States into the war and production of the B-17 rapidly increased. By July 1942 the US began forming the Eighth Air Force in Britain, equipped with B-17Es. The 'E' represented an important improvement over the earlier B-17s, in that it had a tail turret, so eliminating a previous defensive blind spot. On 17 August 1942 United States B-17s carried out a bombing raid on the railway yards at Rouen in France. The real offensive, however, started on 27 January 1943, when B-17s of the USAAF made their first attack on Germany. Initially, casualties were very high because they attacked during daylight hours to achieve greater accuracy and because proper formation flying (to enable a group of airplanes to defend each other with cross-fire) had not yet been formulated. Delivery of the B-17G (the major production version) helped. The 'G' was the first variant to have a gun turret under the nose, so increasing the armament to 13 guns.

Production of the similar B-17F was undertaken by Douglas and Vega, a subsidiary of the Lockheed Aircraft Corp., was taking its toll in speed. The B-17F, though now armed with eleven.50 cal. guns, could only reach 299 mph, but landing speed was up to 90 mph! Service ceiling was 37,500 feet and range 2,880 miles. It took twenty-five and a half minutes to climb to 20,000 feet. Three thousand, four hundred B-17F's were produced by the three companies.

By September, 1943, the Flying Fortress showed its final shape. During firepower tests on the XB-40, a modified B-17F, the advantage of a chin turret was clearly proven and a new series, labeled B-17G, sported this nasal appendage. The Bendix turret held two .50 cal. guns and this model had a total of twelve of these weapons with 6,380 rounds of ammunition. In all, there were 8,680 B-17G's built by Boeing, Vega, and Douglas to make this the largest production variation. Following the first Model 299, the Air Corps purchased 12,725 B-17 type aircraft.

On 19 July 1943 US B-17s and B-24 Liberators carried out the first bombing raid on Rome; and US bombing in Europe reached its high point in February 1945 with a 1000-bomber raid on Berlin, escorted by 400 fighters, and the Dresden raid (alongside the Royal Air Force) which caused a massive fire storm to sweep the city.

Meanwhile, B-17s were also helping to win the war against Japan, although by mid-1943 the larger B-29 had begun to take over the major strategic bombing missions. By the end of production, more than 12700 B-17s had been built, of which a few served with Royal Air Force Coastal Command and the United States Navy for patrol, air-sea rescue, anti-submarine and other duties.

B-17G specifications included a span of 103 feet 9 inches, length of 74 feet 4 inches, and a height of 19 feet 1 inch. The four supercharged Wright R-1820-97 Cyclones delivered 1,200 hp and gave a top speed of 287 mph, cruising at 182 mph. Service ceiling was 35,600 feet, with a range of 3,400 miles. Empty and gross weights were 36,135 pounds and 55,000 pounds. Maximum fuel load was 3,630 gallons.

Cargo conversions of the B-17 were known as C-108.

The First American Missions From England

American air power made its European debut during the summer of 1942. On June 12, Colonel Harry Halverson led thirteen B-24 Liberators on a first daring, long-distance raid against the oil refineries at Ploesti, Rumania. Taking off from Egypt, 1,000 miles from the target, the bombers surprised the enemy. All the planes got safely away, though one B-24 crash landed later.

The first American mission from England took place, appropriately, on the Fourth of July. Six air crews, flying A-20 Boston bombers borrowed from the RAF, joined six British crews on a low-level raid against air bases in Holland. The Germans were warned by radio from a picket ship off the Dutch coast, and two of the bombers flown by Americans were shot down. The bombardiers of two of the other planes were so confused by the camouflaged targets that they failed to drop their bombs at all.

More auspicious was a raid on August 17, against the railroad yards at Rouen. A dozen B-17 Flying Fortresses loaded with three hundred-pound bombs, completed their mission without losses. In the fall, the North African invasion diverted planes and men and temporarily stalled the build-up of U.S. air strength in England. But as the Eighth continued to stab at the enemy, American crews matched the courage and ability of veterans.

On one occasion, for instance, nine B-17's, turning back from a canceled mission against Rotterdam, were jumped by more than twenty German fighters. The Americans fought their way back to England, but in one bomber the pilot was injured and the copilot killed. The bombardier, who had been washed out of flying school, took over the controls and flew the plane back home on two engines