B17

B17 Boeing B-17G Flying Fortress

B-17

B17

The B17 Flying Fortress is one of the most famous airplanes ever built. The B17 prototype first flew July 28, 1935. Few B-17s were in service on Dec. 7, 1941, but production quickly accelerated.

The aircraft served in every World War II combat zone, but is best known for daylight strategic bombing of German industrial targets. Production ended in May 1945, and totaled 12,726.

B17 Specifications

B17 Span: 103 feet, 10 inches
B17 Length: 74 feet, 4 inches
B17 Height: 19 feet, 1 inches
B17 Weight: 55,000 pounds loaded
B17 Armament: Thirteen .50-caliber machine guns with normal bomb load of 6,000 pounds
B17 Engines: Four Wright "Cyclone" R-1820s of 1,200 horsepower each
B17 Cost: $276,000

B-17 Performance

Maximum speed: 300 mph.
Cruising speed: 170 mph.
Range: 1,850 miles
Service Ceiling: 35,000 feet

B-17 Variants
The B-17 went through several alterations in each of its design stages and variants. Of the 13 YB-17s ordered for service testing, 12 were used by the 2nd Bomb Group of Langley Field, Virginia to develop heavy bombing techniques, and the 13th was used for flight testing at the Material Division at Wright Field, Ohio.[24] Experiments on this plane led to the use of a turbo-supercharger, which would become standard on the B-17 line. A 14th plane, the Y1 B-17 A, originally destined for ground testing only, was upgraded with the turbocharger. When this aircraft had finished testing, it was re-designated the B-17 A, and in April 1938 was the first plane to enter service under the B-17 designation.[24][26]

As the production line developed, Boeing engineers continued to improve upon the basic design. To enhance performance at slower speeds, the B-17B was altered to include larger rudder and flaps.[41] The B-17C changed from gun blisters to flush, oval-shaped windows.[64] Most significantly, with the B-17E version, the fuselage was extended by 10 feet, a much larger vertical fin and rudder were incorporated into the original design, a gunner's position in the tail and an improved nose were added. The engines were upgraded to more powerful versions several times, and similarly, the gun stations were altered on numerous occasions to enhance their effectiveness.[66]

By the time the definitive B-17 G appeared, the number of guns had been increased from seven to 13, the designs of the gun stations were finalized, and other adjustments were complete. The B-17 G was the final version of the B-17, incorporating all changes made to its predecessor, the B-17 F, and in total 8,680 were built, the last one on 9 April 1945.[68] Many B-17 Gs were converted for other missions such as cargo hauling, engine testing and reconnaissance.[69] Initially designated SB-17G, a number of B-17Gs were also converted for search-and-rescue duties, later to be redesignated B-17H.[70]

Two versions of the B-17 were flown under different designations. These were the XB-38 and the YB-40. The XB-38 was an engine test-bed for Allison V-1710 liquid-cooled engines, should the Wright engines normally used on the B-17 become unavailable. The YB-40 was a heavily armed modification of the standard B-17 used before the P-51 Mustang, an effective long-range fighter, became available to act as escort. Additional armament included a power turret in the radio-room, a chin turret (which went on to become standard with the B-17G ) and twin .50 caliber (12.7 mm) guns in the waist positions. The ammunition load was over 11,000 rounds, making the YB-40 well over 10,000 pounds (4,500 kg) heavier than a fully loaded B-17F. Unfortunately, the YB-40s with their numerous heavy modifications had trouble keeping up with empty bombers, and so, together with the advent of the P-51 Mustang, the project was abandoned and finally phased out in July 1943.

Late in World War II, at least 25 B-17s were fitted with radio controls, loaded with 20,000 pounds (9,000 kg) of high-explosives, dubbed "BQ-7 Aphrodite missiles", and used against U-boat pens and bomb-resistant fortifications. Joseph P. Kennedy Jr., future US president John F. Kennedy's eldest brother, was killed in the development effort. Because few (if any) BQ-7s hit their target, the Aphrodite project was scrapped in early 1945. During and after World War II, a number of weapons were tested and used operationally on B-17s. Some of these weapons included "razons" (radio-guided) glide bombs, and Ford-Republic JB-2 Loons, also nicknamed Thunderbugs— American reverse-engineered models of the German V-1 Buzz Bomb. A much-used travelling airborne shot of a V-1/JB-2 launch in World War II documentaries was filmed from a USAF A-26 of the Air Proving Grounds, Eglin Air Force Base, launched from Santa Rosa Island, Florida. In the late 1950s, the last B-17s in United States Air Force service were QB-17 drones and DB-17P drone controllers, plus a few polished VB-17 squadron "hacks". The last operational mission flown by a USAF Fortress was conducted on 6 August 1959, when DB-17P 44-83684 directed QB-17G 44-83717 out of Holloman Air Force Base as a target for a Falcon air-to-air missile fired from an F-101 Voodoo fighter. A retirement ceremony was held several days later at Holloman, after which 44-83684 was retired to MASDC at Davis-Monthan Air Force Base.

(credits: US Air Force History Support Office)