B-17G Flying Fortress Specifications:
- Length: 74 ft. 4 in.
- Wingspan: 103 ft. 9 in.
- Height: 19 ft. 1 in.
- Wing Area: 1,420 sq. ft.
- Empty Weight: 36,135 lbs.
- Loaded Weight: 54,000 lbs.
- Crew: 10
- Power Plant: 4 × Wright R-1820-97 Cyclone turbo-supercharged radial engines, 1,200 hp each
- Range: 2,000 miles
- Max Speed: 287 mph
- Ceiling: 35,600 ft.
- Guns: 13 × .50 in (12.7 mm) M2 Browning machine guns
- Bombs: 4,500-8,000 lbs. depending on range
B-17 Flying Fortress Design & Development:
Seeking an effective heavy bomber to replace the Martin B-10, the US Army Air Corps (USAAC) issued a call for proposals on August 8, 1934. Requirements for the new aircraft included the ability to cruise at 200 mph at 10,000 ft. for ten hours with a "useful" bomb load. While the USAAC desired a range of 2,000 miles and top speed of 250 mph, these were not required. Eager to enter the competition, Boeing assembled a team of engineers to develop a prototype. Led by E. Gifford Emery and Edward Curtis Wells, the team began drawing inspiration from other company designs such as the Boeing 247 transport and XB-15 bomber.
Constructed at the company's expense, the team developed the Model 299 which was powered by four Pratt & Whitney R-1690 engines and was capable of lifting a 4,800 lb. bomb load. For defense, the aircraft mounted five machine guns. This imposing look led Seattle Times reporter Richard Williams to dub the aircraft the "Flying Fortress." Seeing the advantage to the name, Boeing quickly trademarked it and applied to the new bomber. On July 28, 1935, the prototype first flew with Boeing test pilot Leslie Tower at the controls. With the initial flight a success, the Model 299 was flown to Wright Field, OH for trials.
At Wright Field the Boeing Model 299 competed against the twin-engined Douglas DB-1 and Martin Model 146 for the USAAC contract. Competing in the fly-off, the Boeing entry displayed superior performance to the competition and impressed Major General Frank M. Andrews with the range that a four-engine aircraft offered. This opinion was shared by the procurement officers and Boeing was awarded a contract for 65 aircraft. With this in hand, development of the aircraft continued through the fall until an accident on October 30 destroyed the prototype and halted the program.
Rebirth of the B-17:
As result of the crash, Chief of Staff General Malin Craig canceled the contract and purchased aircraft from Douglas instead. Still interested in the Model 299, now dubbed YB-17, the USAAC utilized a loophole to purchase 13 aircraft from Boeing in January 1936. While 12 were assigned to the 2nd Bombardment Group for developing bombing tactics, the last aircraft was given to the Material Division at Wright Field for flight testing. A fourteenth aircraft was also built and upgraded with turbochargers which increased speed and ceiling. Delivered in January 1939, it was dubbed B-17A and became the first operational type.
An Evolving Aircraft:
Only one B-17A was built as Boeing engineers worked tirelessly to improve the aircraft as it moved into production. Including a larger rudder and flaps, 39 B-17Bs were built before switching to the B-17C which possessed an altered gun arrangement. The first model to see large-scale production , the B-17E (512 aircraft) had the fuselage extended by ten feet as well as the addition of more powerful engines, a larger rudder, a tail gunner position, and an improved nose. This was further refined to the B-17F (3,405) which appeared in 1942. The definitive variant, the B-17G (8,680) featured 13 guns and a crew of ten.
The first combat use of the B-17 came not with the USAAC (US Army Air Forces after 1941), but with the Royal Air Force. Lacking a true heavy bomber at the start of World War II, the RAF purchased 20 B-17Cs. Designating the aircraft Fortress Mk I, the aircraft performed poorly during high-altitude raids in the summer of 1941. After eight aircraft were lost, the RAF transferred the remaining aircraft to Coastal Command for long-range maritime patrols. Later in the war, additional B-17s were purchased for use with Coastal Command and the aircraft was credited with sinking 11 u-boats.
Backbone of the USAAF:
With the US entry into the conflict after the attack on Pearl Harbor, the USAAF began deploying B-17s to England as part of the Eighth Air Force. On August 17, 1942, American B-17s flew their first raid over occupied Europe when they struck railroad yards at Rouen-Sotteville, France. As American strength grew, the USAAF took over daylight bombing from the British who had switched to night attacks due to heavy losses. In the wake of the January 1943 Casablanca Conference, American and British bombing efforts were directed into Operation Pointblank which sought to establish air superiority over Europe.
Key to the success of Pointblank was attacks against the German aircraft industry and Luftwaffe airfields. While some initially believed that the B-17's heavy defensive armament would protect it against enemy fighter attacks, missions over Germany quickly disproved this notion. As the Allies lacked a fighter with sufficient range to protect bomber formations to and from targets in Germany, B-17 losses quickly mounted during 1943. Bearing the brunt of the USAAF's strategic bombing workload along with the B-24 Liberator, B-17 formations took shocking casualties during missions such as the Schweinfurt-Regensburg raids.
Following "Black Thursday" in October 1943, which resulted in the loss of 77 B-17s, daylight operations were suspended pending the arrival of a suitable escort fighter. These arrived in early 1944 in the form of the North American P-51 Mustang and drop tank-equipped Republic P-47 Thunderbolts. Renewing the Combined Bomber Offensive, B-17s incurred much lighter losses as their "little friends" dealt with the German fighters.
B-17s had more success in March 1943 during the Battle of the Bismarck Sea. Utilizing skip bombing rather than attacking from high altitude, they sank three Japanese ships. Despite this victory, the B-17 was not as effective in the Pacific and the USAAF transitioned aircrews to other types by mid-1943. During the course of World War II, the USAAF lost around 4,750 B-17s in combat, nearly a third of all built. USAAF B-17 inventory peaked in August 1944 at 4,574 aircraft. In the war over Europe, B-17s dropped 640,036 tons of bombs on enemy targets.
Final Years of the B-17
With the end of the war, the USAAF declared the B-17 obsolete and the majority of the surviving aircraft were returned to the United States and scrapped. Some aircraft were retained for search and rescue operations as well as photo reconnaissance platforms into the early 1950s. Other aircraft were transferred to the US Navy and redesignated PB-1. Several PB-1s were fitted with the APS-20 search radar and used as antisubmarine warfare and early warning aircraft with designation PB-1W. These aircraft were phased out in 1955. The US Coast Guard also utilized the B-17 after the war for iceberg patrols and search and rescue missions. Other retired B-17s saw later service in civilian uses such as aerial spraying and fire fighting. During its career, the B-17 saw active duty with numerous nations including the Soviet Union, Brazil, France, Israel, Portugal, and Colombia.