Екінші дүниежүзілік соғыстағы Boeing B-17 Flying Fortress ұшағының түрлері мен даму тарихы

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The following is an extensive catalogue of the variants and specific unique elements of each variant and/or design stage of the Boeing B 17 Flying Fortress, a heavy bomber used by the United States Army Air Forces and other Allied air forces during World War II.

The aircraft that became the sole Y1B 17A was originally ordered as a static test bed. However, when one of the Y1B 17s survived an inadvertent violent spin during a flight in a thunderhead, Army Air Corps leaders decided that there would be no need for static testing. Instead, it was used as a testbed for improving engine performance. After studying a variety of configurations, use of a ventral nacelle mount turbocharger was chosen for each of its four engines. A successive series of General Electric manufactured turbochargers would equip B 17s as standard items, starting with the first production model, allowing it to fly higher and faster than the Y1B 17. When testing was completed, the Y1B 17A was reconfigured as a B 17A.

With the passage of the Lend lease Act in 1941, the Royal Air Force requested B 17s. At that time, the US Army Air Corps was suffering from shortages, but supplied 20 to the RAF. Though the Air Corps hadn't cleared the B 17 for combat, they were desperately needed in Britain. The 20 ferried bombers were production B 17Cs (company designation Model 299T), designated Fortress Mk I by the RAF. The aircraft's single .30 caliber nose mounted machine guns were replaced with Brownings. Following delivery, the 20 Fortress Mk. Is went almost immediately into frontline service, however they performed poorly. By September 1941, 39 sorties had only resulted in 22 missions, with nearly half of the sorties aborted due to mechanical and electrical problems. Eight of the 20 aircraft had been destroyed by September, half to accidents. Their guns froze up at altitude and were unable to protect the Fortresses from attack and their effectiveness as bombers was also limited, largely because of problems with achieving an adequate level of bombing accuracy.

In the middle of 1942, 45 B 17Es were transferred to the RAF, where they served under the designation Fortress Mk. IIA. Because of the shortcomings experienced with the Mk. I, the RAF did not use the Mk. IIA in its intended role but instead they were operated by the Coastal Command for anti submarine patrols.

19 B 17Fs were transferred to the RAF, where they served with RAF Coastal Command as the Fortress Mk. II.

Eighty five B 17Gs were transferred to the RAF, where they received the designation Fortress Mk. III. Three were assigned to Coastal Command in the Azores and were fitted with radar before being reused by meteorological survey squadrons. The rest were operated as Fortress Mk. III (SD) (Special Duties) from February 1944 by two squadrons of Bomber Command's No. 100 Group RAF, where they carried out electronic countermeasures to confuse or jam German radar in support of bombing missions. These carried an extensive array of electronic equipment including airborne Grocer air interception jammers, the Jostle VHF jammer, Monica tail warning receiver, Gee and LORAN for navigation, and an H2S radar which replaced the chin turret. They were also used as decoys during night bombing attacks. Fortress Mk. IIIs were operational until the units disbanded in July 1945.

The XB 38 was a modification undertaken by the Vega division of Lockheed on the ninth B 17E built. It was to test the feasibility of using liquid cooled Allison V 1710 89 engines, if the Wright R 1820 engine became scarce. Completing the modifications took less than a year, and the XB 38 made its first flight on 19 May 1943. While it showed a slightly higher top speed, after just a few flights it had to be grounded due to a problem with engine manifold joints leaking exhaust gases. Following this problem being resolved, testing continued until the ninth flight on 16 June 1943 when the inboard starboard engine caught fire, and the crew bailed out. The XB 38 was destroyed and the project was cancelled. The gains in modification were minimal and would have been disruptive to the existing Flying Fortress production. Allison engines were also considered to be more badly needed for fighters.

Prior to the introduction of the P 51 Mustang, a B 17 "gunship" escort variant called the YB 40 was trialled. This aircraft differed from the standard B 17 in that a second dorsal turret was installed atop the radio operator's position between the forward dorsal turret and the waist guns, where only an upward firing single or double Browning M2 had been mounted; and a single machine gun at each waist station was replaced by a pair of guns, of basically the same twin mount design used for the tail guns. In addition, the bombardier's equipment was replaced with twin machine guns in a remotely operated "chin" turret directly under the bombardier's position, augmenting the existing "cheek" machine guns; and the bomb bay was converted to a .50 caliber magazine. The YB 40 would provide a heavily armed gunship escort capable of accompanying the bombers all the way to a target and back. The aircraft was deemed a failure, however, because it could not keep up with standard B 17s once they had dropped their heavy bomb loads. It was withdrawn from service after just fourteen missions. (Twenty six were built: one XB 40 prototype, 21 YB 40 pre production aircraft, four TB 40 training aircraft.)

Four B 17s were converted to serve as cargo carriers and V. I. P. transports under the designation C 108 Flying Fortress. Many more served in the same roles under the designations CB 17 and VB 17, respectively. The first of them, designated XC 108, was a B 17E partially stripped of military equipment and outfitted for passengers. It served as a V. I. P. transport for General Douglas MacArthur. A similar conversion was made on a B 17F, designated YC 108. The third plane, designated XC 108A, was made to test the feasibility of converting obsolete bombers to cargo aircraft. The B 17E chosen for the conversion was based in India, where it ferried supplies over the Himalaya to the base for the B 29 Superfortress in Chengdu, China. It proved a difficult aircraft to maintain, due to lack of spares for the Cyclone engines, and was returned to the United States, where it was based in Bangor, Maine, and flew a cargo route to Scotland until the end of the war. It was sold to a local dealer for scrap, but the airframe survived, and is currently being restored in Illinois. A final aircraft was built under the designation XC 108B, and was used as a tanker to transport fuel from India to Chengdu.

Several B 17s were converted to long range photographic reconnaissance aircraft, designated F 9 Flying Fortress. (The F was for 'foto' and is not to be confused with the use of F for 'fighter'.) The first F 9 aircraft were sixteen B 17Fs, with bombing equipment replaced by photographic equipment. Some of the defensive armament was kept. An uncertain number of additional airframes were converted to a similar configuration to the F 9, but differed in minor details of their cameras, and received the designation F 9A. Some of these, along with more B 17Fs, received further camera alterations and became the F 9B. The final model was the F 9C, which was given to ten B 17G, converted in a similar fashion to the previous aircraft. Those surviving in 1948 were initially redesignated RB 17G (R indicating 'reconnaissance'). FB 17: Post war redesignation of all F 9 photo reconnaissance aircraft.

Late in World War II, at least 25 B 17s were fitted with radio controls as BQ 7 drones for Operation Aphrodite. Loaded with of Torpex high explosive and enough fuel for , they were to be used to attack Nazi U boat pens, V 1 flying bomb sites, and bomb resistant fortifications. The BQ 7s would be taken up to 609.60 m by two volunteers before transferring control to another B 17 and bailing out while still over England. The controlling B 17 would follow the BQ 7, aim to at the target and set its controls for a collision course, before itself returning. The normal cockpit lost its roof and the fairing behind it was removed. Because the remote control hardware was inadequate, Operation Aphrodite was riddled with problems. Between August 1944 and January 1945, 15 BQ 7s were launched against Germany, but none hit their targets, and several crew were killed, many in parachuting accidents. One BQ 7 left a 30.48 m crater in Britain and another circled an English port out of control. The program was cancelled in early 1945.

After the war, the United States Coast Guard (USCG) realized the need for a long range search and rescue aircraft to supplement its peace time Sea Air Rescue (SAR) capabilities. Concurrently, the Army Air Force was retiring thousands of B 17 four engine bombers, many still "factory new" as they were delivered too late to see action. The USCG, always quick to take advantage of anything they could get inexpensively, requested that the Army Air Force loan eighteen of the bombers to the Coast Guard. The powerful, long legged and stable bombers proved to be excellent additions to the Coast Guard's aviation fleet. The Army Air Force had developed a lifeboat that was slung underneath the fuselage of a B 17 that would be dropped to survivors in the water. A parachute rig would deploy from the lifeboat after its release and allow it to descend safely to the surface. The Coast Guard adopted the A 1 lifeboat for many of its PB 1Gs (the naval designation for the Flying Fortress). Furthermore the PB 1Gs were equipped with an ASV radar to assist in the SAR operations. Additionally, these aircraft were also used for the International Ice Patrol while another of the versatile PB 1Gs was modified to carry a nine lens, 1.5 million dollar, aerial camera for mapping purposes. Interestingly, the Norden bombsight, used by the B 17s in their bombing campaign against Nazi Germany, was kept with this PB 1G and used to pinpoint targets for the camera. In total 17 PB 1Gs served with the Coast Guard from 1945 through 1959. The final flight of the last PB 1G in USCG service ended at 1:46 p. m. on Wednesday 14 October 1959 when PB 1G 77254 landed at AIRSTA Elizabeth City. She had faithfully served the nation's oldest continuous sea service for fourteen years.