The Boeing B-17 Flying Fortress four-engine heavy bomber is one of the most famous and successful airplanes ever built. The B-17 received the name “Flying Fortress” from a Seattle news reporter who commented on its defensive firepower, and said “It’s a Flying Fortress”.
On 8 August 1934, the United State Army Air Corps (USAAC) tendered a proposal for a multiengine 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 for it to carry a “useful bombload” at an altitude of 10,000 ft (3,000 m) for 10 hours with a top speed of at least 200 mph (320 km/h).
They also desired, but did not require, a range of 2,000 mi (3,200 km) and a speed of 250 mph (400 km/h). The competition for the Air Corps contract was to be decided by a “fly-off” at Wilbur Wright Field in Dayton, Ohio.
Competing against the Douglas DB-1 and Martin model 146 for a contract to build 200 bombers, the Boeing entry (prototype Model 299/XB-17) outperformed both competitors and exceeded the Air Corps’ performance specifications. Although Boeing lost the contract (to the Douglas B-18 Bolo) because the prototype crashed, the Air Corps ordered 13 more B-17s for further evaluation.
From its introduction in 1938, the B-17 Flying Fortress evolved through numerous design advances, becoming the third most produced bomber of all time, behind the four-engine B-24 and the German multirole, twin-engine Ju88.
B-17 Model Evolution
After several changes on the prototype model 299 (changes models YB-17, YB-17A, B-17B through to B-17D) the B-17E was the first mass-produced model Flying Fortress, carried nine machine guns and a 4,000-pound bomb load. The airplane was several tons heavier than the prototypes and was loaded with armament. It was the first Boeing airplane with the distinctive tail for improved control and stability during high-altitude bombing. Each version was more heavily armed.
The B-17E was indeed an extensive revision of the Model 299 design. The fuselage was extended by 10 ft, and 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 earlier -B through -D versions, but featured the addition of an electrically-powered manned dorsal gun turret just behind the cockpit. The tail turret eliminated a previous defensive blind spot.
B-17F variants were the primary versions flying for the Eighth Air Force to face the Nazis in 1943. This model had standardized the manned Sperry ball turret for ventral defense, along with an enlarged, nearly frameless Plexiglas bombardier’s nose enclosure for much improved forward vision.
Model B-17G and the 457th Bomb Group
The B-17G was the result of an almost continuous improvement program of earlier B-17 models. Because 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.
By the time the definitive B-17G appeared, the number of guns had been increased from seven to 13, 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, and in total, 8,680 were built, the last on 28 July 1945.
The model flown by the 457th Bomb Group was the B17-G model.
Specifications of the B-17G Flying Fortress (final production model)
Armament: 13 .50 cal. machine guns; normal bomb load of 6,000 lbs.
Engines: 4x Wright Cyclone R-1820s of 1,200 hp each
Maximum speed: 300Mph
Cruising speed: 170mph
Range: 1,850 miles
Ceiling: 35,000 ft.
Span: 103ft. 10 in.
Length: 74 ft 4 in.
Height: 19ft. 1 in.
Weight: 55,000 lbs. loaded