Question:  Memphis Belle is the nickname of a four-engine bomber which was introduced in what year?

full_context: Document 1: Memphis Belle (film): Memphis Belle is a 1990 British-American war drama film directed by Michael Caton-Jones and written by Monte Merrick. The film features an all-star cast with Matthew Modine, Eric Stoltz, and Harry Connick Jr. (in his film debut) in leading roles. "Memphis Belle" is a fictionalization of the 1943 documentary "" by director William Wyler, about the 25th and last mission of an American Boeing B-17 Flying Fortress bomber, the "Memphis Belle", based in England during World War II. The 1990 version was co-produced by David Puttnam and Wyler's daughter Catherine, and dedicated to her father. The film closes with a dedication to all airmen, friend or foe, who fought in the skies above Europe during World War II.
Document 2: B-17 Flying Fortress (video game): B-17 Flying Fortress or B-17 Flying Fortress World War II Bombers in Action is a flight simulation/role-playing video game released in 1992 for MS-DOS by MicroProse. Amiga and Atari ST versions were released a year later. The game simulates training, combat missions and sorties in a tour of duty in the Eighth Air Force of the United States Army Air Forces in the European Theater of Operations aboard a Boeing B-17 Flying Fortress bomber during World War II.
Document 3: Lady for a Night: Lady for a Night is a 1942 American drama film starring Joan Blondell and John Wayne. The World War II B-17 bomber the "Memphis Belle" is named after a steamboat in this film. It is also known as The Lady From New Orleans, Memphis Belle and Lady of New Orleans.
Document 4: Memphis Belle: A Story of a Flying Fortress: The Memphis Belle: A Story of a Flying Fortress is a 1944 documentary film which provides an account of the final mission of the crew of the "Memphis Belle", a Boeing B-17 Flying Fortress. In May 1943 it became the first U.S. Army Air Forces heavy bomber to complete 25 missions over Europe and return to the United States.
Document 5: Enola Gay: The Enola Gay ( ) is a Boeing B-29 Superfortress bomber, named for Enola Gay Tibbets, the mother of the pilot, Colonel Paul Tibbets, who selected the aircraft while it was still on the assembly line. On 6 August 1945, during the final stages of World War II, it became the first aircraft to drop an atomic bomb. The bomb, code-named "Little Boy", was targeted at the city of Hiroshima, Japan, and caused unprecedented destruction. "Enola Gay" participated in the second atomic attack as the weather reconnaissance aircraft for the primary target of Kokura. Clouds and drifting smoke resulted in a secondary target, Nagasaki, being bombed instead.
Document 6: List of Boeing B-17 Flying Fortress variants: 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 heavy bomber. For a broader article on the history of the B-17, see B-17 Flying Fortress.
Document 7: Boeing XF8B: The Boeing XF8B (Model 400) was a single-engine aircraft developed by Boeing during World War II to provide the United States Navy a long-range shipboard fighter aircraft. The XF8B was intended for operation against the Japanese home islands from aircraft carriers outside the range of Japanese land-based aircraft. Designed for various roles including interceptor, long-range escort fighter, dive-bomber, and torpedo bomber, the final design embodied a number of innovative features in order to accomplish the various roles. Despite its formidable capabilities, the XF8B-1 was fated never to enter series production.
Document 8: Boeing B-17 Flying Fortress: The Boeing B-17 Flying Fortress is a four-engine heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Competing against Douglas and Martin 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 B-24 and the multirole Ju 88.
Document 9: Junkers Ju 88: The Junkers Ju 88 was a German World War II "Luftwaffe" twin-engined multirole combat aircraft. Junkers Flugzeug- und Motorenwerke (JFM) designed the plane in the mid-1930s as a so-called "Schnellbomber" (fast bomber) that would be too fast for fighters of its era to intercept. It suffered from a number of technical problems during its development and early operational periods but became one of the most versatile combat aircraft of the war. Like a number of other "Luftwaffe" bombers, it served as a bomber, dive bomber, night fighter, torpedo bomber, reconnaissance aircraft, heavy fighter and at the end of the war, as a flying bomb.
Document 10: North American P-51 Mustang: The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in 1940 by North American Aviation (NAA) in response to a requirement of the British Purchasing Commission. The Purchasing Commission approached North American Aviation to build Curtiss P-40 fighters under license for the Royal Air Force (RAF). Rather than build an old design from another company, North American Aviation proposed the design and production of a more modern fighter. The prototype NA-73X airframe was rolled out on 9 September 1940, 102 days after the contract was signed, and first flew on 26 October.
Document 11: B-17G &quot;Flying Fortress&quot; No. 44-83690: B-17G "Flying Fortress" No. 44-83690 is a historic B-17 Flying Fortress Heavy bomber located at the Aviation Museum, Grissom Air Force Base in Pipe Creek Township, Miami County, Indiana. It was built by the Douglas Aircraft Company and delivered for use on May 9, 1945. It was flown to Grissom Air Force Base for display as a museum piece in 1961, and subsequently restored.
Document 12: Memphis Belle (aircraft): Memphis Belle is the nickname of a Boeing B-17F Flying Fortress that was used during the Second World War that inspired the making of two motion pictures: a 1944 documentary film, "", and a 1990 Hollywood feature film, "Memphis Belle". The aircraft was one of the first United States Army Air Forces B-17 heavy bombers to complete 25 combat missions with her crew intact. The aircraft and crew then returned to the United States to sell war bonds. As of 2017, the aircraft was being restored at the National Museum of the United States Air Force at Wright-Patterson AFB in Dayton, Ohio with plans to put it on display May 17, 2018.
Document 13: Don F. Pratt Memorial Museum: Don F. Pratt Memorial Museum is an official U.S. Army Museum located in Building 5702 on Tennessee Avenue at Fort Campbell, Kentucky. Military artifacts and memorabilia are available to touch and view at the museum which features interior and exterior exhibits that help visitors better reflect on military history. Included are helicopters, planes, jeeps, trucks, tanks, captured enemy weapons and equipment from World War II, the Korean War, Vietnam, the Persian Gulf War, Operation Iraqi Freedom and Operation Enduring Freedom in Afghanistan. Artifacts on exhibit include a recruiter's jeep from the 1970s and items which had belonged high-ranking Nazi officials including Adolf Hitler, Hermann Goering and Julius Streicher, captured by the 101st Airborne Division in 1945 in Berchtesgaden. The main museum theme focuses on the history of Fort Campbell and the 101st Airborne Division, but also visitors experience some of this by stepping inside a restored CG-4A cargo glider. The museum also has exhibits dedicated to the 11th Airborne Division, 5th Special Forces Group, 160th Special Operations Aviation Regiment, and the 12th, 14th, and 20th Armored Divisions which trained at Fort Campbell during World War II.
Document 14: 91st Bombardment Group: The 91st Bomb Group (Heavy) was an air combat unit of the United States Army Air Forces during the Second World War. Classified as a heavy bombardment group, the 91st operated B-17 Flying Fortress aircraft and was known unofficially as "The Ragged Irregulars" or as "Wray's Ragged Irregulars", after the commander who took the group to England. During its service in World War II the unit consisted of the 322nd, 323rd, 324th, and 401st Bomb Squadrons. The 91st Bomb Group is most noted as the unit in which the bomber "Memphis Belle" flew, and for having suffered the greatest number of losses of any heavy bomb group in World War II.
Document 15: List of surviving Boeing B-17 Flying Fortresses: The Boeing B-17 Flying Fortress is a four-engine heavy bomber aircraft primarily employed by the United States Army Air Forces (USAAF) during World War II. Developed by Boeing, a total of 12,731 aircraft had been produced by Boeing, Douglas and Lockheed from 1936 until 1945. Over 8,000 were lost in either combat operations or training accidents. The remaining combat veterans and early production models were stored and later scrapped in the vast scrap drives of the late 1940s, many going to aircraft boneyards like Davis-Monthan Air Force Base in Tucson, Arizona, the largest of its kind within the United States' borders.
ground_truth: 1938