Aircraft Factfile and Recognition Guide - B-17 Flying Fortress

Background

The Flying Fortress was designed for a USAAC competition, announced in 1934, to find a modern replacement for the assorted Keystone biplane bombers, then in service. The requirement was for a multi-engined bomber to be used mostly as a coastal-defense aircraft. Specifications required were: a range of at least 1,020 miles (1,641 km), but preferably 2,200 miles (3,540 km); a speed of at least 200 mph (322 km/h), but preferably 250 mph (402 km/h); a capability of carrying a 2,000 lb (907 kg) bomb load. A Boeing design team began work on the Model 299 prototype in June 1934, and construction began in August of the same year (The most significant rival to the Model 299 was the Douglas DB-1, which later developed into the Douglas B-18 Bolo.). The Model 299 was make-or-break gamble for Boeing, which first flew on July 28,1935, and eventually won the competition. Boeing built a few preproduction YB-17s (later redesignated B-17As), followed by one YB-17A, and then followed by thirty-nine B-17Bs. Since funding was lacking at the time, only thirty Flying Fortresses were fully operational when Hitler's forces invaded Poland in September 1939. The US was not involved in the fighting in Europe at the time, so it did not seem to be a matter of urgency. However, as it became clearer that US involvement was inevitable, after the Munich Crisis, orders for B-17s were increased. Thirty-eight B-17Cs and forty-two B-17Ds were built before the first large production run began with the B-17E variant. Twenty B-17Cs were delivered to the RAF as Fortress Is, which quickly showed that defensive armament was inadequate, (the B-17C carried seven 50-cal. machine-guns) and at high altitude raids of 30,000 ft. (9,144 m), the defensive guns froze up, when they tried to fire them. Also bombs raids at high altitudes proved to be very inaccurate, and most of the bombs were missing their targets. The airplane was revised as the Model 299O, with the most important changes incorporated into the Model 299H (B-17C and B-17D). Modifications included self-sealing tanks and additional armor for crew protection.

In September of 1941, the B-17E 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. Aesthetically, the B-17E was a retrograde step, but more importantly, it would turn a relative failure, into an outstanding military success. The B-17E enveloped a deadly stinger of twin .50-cal. machine guns, and a remote controlled belly turret held two more .50s. One hundred-twelve B-17Es were built, followed by four hundred more, with a manned Sperry ball turret replacing the remote system. The B-17E was lengthened to 73 feet 10 inches (22.5 m) to accommodate the new defensive tail position. Top speed was 317 mph (510 km/h), cruising at over 200 mph (321 km/h) with 4,000 lb (1814 kg) of bombs. The crew was increased from nine to ten members. The additional equipment made the aircraft seven tons heavier than the original Model 299.

The Pearl Harbor attack of December 7, 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, eliminating a previous defensive blind spot. Production of the B-17F was undertaken by Douglas and Vega, a subsidiary of the Lockheed Aircraft Corp., but modifications were taking their toll in airspeed. There were more than four hundred modifications on the B-17F. The B-17F, now armed with eleven .50-cal. guns, could only reach 299 mph (481 km/h), but landing speed was up to 90 mph (144 km/h)! Service ceiling was 37,500 ft. (11,430 m) and range 2,880 miles (4,634 km). It took twenty-five and a half minutes to climb to 20,000 ft. (6,096 m). Three thousand, four hundred B-17Fs were produced by the three companies.

On August 17, 1942, United States B-17s carried out a bombing raid on the railway yards at Rouen in France. The real offensive, however, started on January 27, 1943, when B-17s of the USAAF made their first attacks 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 crossfire) had not yet been formulated. Also the B-17F lacked adequate defense against a head-on attack. By September 1943, the Flying Fortress showed its final shape during firepower tests on the XB-40, a modified B-17F with the advantage of a "chin" turret. The success of the chin turret, led to the delivery of the B-17G (the major production version), which was the first production variant to have a chin turret installed, under the nose. The Bendix turret held two .50-cal. guns, which increased the armament to thirteen guns. In all, there were 8,680 B-17Gs built by Boeing, Vega, and Douglas to make this the largest production variation. Produced in greater numbers than any other single model, more B-17Gs were lost, than any other model. B-17G specifications included a span of 103 feet 9 inches (31.6 m), length of 74 feet 4 inches (22.6 m), and a height of 19 feet 1 inch (5.8 m). The four supercharged Wright R-1820-97 Cyclones delivered 1,200 hp (895 kW) and gave a top speed of 287 mph (462 km/h), cruising at 182 mph (293 km/h). Service ceiling was 35,800 ft. (10,850 m), with a max. range of 3,400 miles (5,471 km). Empty and gross weights were 36,135 lb (16,390 kg) and 65,500 lb (29,710 kg). Maximum fuel load was 3,630 gallons (13,741 liters).

Recognizing the B-17

The B-17 is a very easy aircraft to identify on the ground as well as from the air.  Here's tips on how you can identify the B-17.

Wings: Low, straight wing with curved wingtips.
Engine(s): Four engines mounted on the main wings with small cowlings and three-bladed propellers.
Fuselage: Short, slim, bubble-canopy-like nose for bombardier and traditional windows for pilot and copilot with the fuselage tapering off to the tail.  Lower nose gun prominent in the B-17G while side gunners, ball turret, and rear gunner are prominent in all versions.
Tail: Large, very round tail smoothly meeting with fuselage and large, straight tail planes that curve towards the tip mounted midway on fuselage.

Specifications

Sources: Aviation History Online - B-17, Air Force History - B-17 Wikipedia B-17 Flying Fortress

© 2004-2007 Steven Holzinger