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The Mitsubishi A6M "Zero" is a long-range fighter aircraft, manufactured by Mitsubishi Heavy Industries, and operated by the Imperial Japanese Navy from 1940 to 1945. The A6M was designated as the , or the Mitsubishi A6M Rei-sen. The A6M was usually referred to by its pilots as the "Reisen" (zero fighter), "0" being the last digit of the Imperial year 2600 (1940) when it entered service with the Imperial Navy. The official Allied reporting name was "Zeke", although the use of the name "Zero" was later commonly adopted by the Allies as well. When it was introduced early in World War II, the Zero was considered the most capable carrier-based fighter in the world, combining excellent maneuverability and very long range.〔Hawks, Chuck. ("The Best Fighter Planes of World War II" ). chuckhawks.com. Retrieved: 18 January 2007.〕 The Imperial Japanese Navy Air Service ("IJNAS") also frequently used the type as a land-based fighter. In early combat operations, the Zero gained a legendary reputation as a dogfighter,〔Young 2013, p. 36.〕 achieving the outstanding kill ratio of 12 to 1,〔Thompson with Smith 2008, p. 231.〕 but by mid-1942 a combination of new tactics and the introduction of better equipment enabled the Allied pilots to engage the Zero on generally equal terms.〔Mersky, Peter B. (Cmdr. USNR). ("Time of the Aces: Marine Pilots in the Solomons, 1942–1944." ) ''ibiblio.org''. Retrieved: 18 January 2007.〕 By 1943, inherent design weaknesses and the failure to develop more powerful aircraft engines meant that the Zero became less effective against newer enemy fighters, which possessed greater firepower, armor, and speed, and approached the Zero's maneuverability. Although the Mitsubishi A6M was outdated by 1944, design delays and production difficulties of newer Japanese aircraft types meant that it continued to serve in a front line role until the end of the war. During the final years of the War in the Pacific, the Zero was also adapted for use in ''kamikaze'' operations.〔Willmott 1980, pp. 40–41.〕 During the course of the war, Japan produced more Zeros than any other model of combat aircraft.〔Angelucci and Matricardi 1978, p. 138.〕 ==Design and development== The Mitsubishi A5M fighter was just entering service in early 1937, when the Imperial Japanese Navy started looking for its eventual replacement. In May, they issued specification 12-Shi for a new carrier-based fighter, sending it to Nakajima and Mitsubishi. Both firms started preliminary design work while they awaited more definitive requirements to be handed over in a few months. Based on the experiences of the A5M in China, the Imperial Japanese Navy sent out updated requirements in October calling for a speed of and a climb to in 3.5 min. With drop tanks, they wanted an endurance of two hours at normal power, or six to eight hours at economical cruising speed. Armament was to consist of two 20 mm cannons, two 7.7 mm (.303 in) machine guns and two or bombs. A complete radio set was to be mounted in all aircraft, along with a radio direction finder for long-range navigation. The maneuverability was to be at least equal to that of the A5M, while the wingspan had to be less than 12 m (39 ft) to allow for use on an aircraft carrier. All this was to be achieved with available engines, a significant design limitation. Nakajima's team considered the new requirements unachievable and pulled out of the competition in January. Mitsubishi's chief designer, Jiro Horikoshi, thought that the requirements could be met, but only if the aircraft could be made as light as possible. Every possible weight-saving measure was incorporated into the design. Most of the aircraft was built of a new top-secret aluminium alloy developed by Sumitomo Metal Industries in 1936. Called Extra Super Duralumin (ESD), it was lighter, stronger and more ductile than other alloys (e.g. 24S alloy) used at the time, but was prone to corrosive attack, which made it brittle.〔Yoshio, Baba.("Extra super duralumin and successive aluminum alloys for aircraft." ) ''Journal of Japan Institute of Light Metals (Sumitomo Light Metal Ind. Ltd., Japan),'' Volume 39, Issue 5, pp. 378-395. Retrieved: 22 November 2015.〕 This detrimental effect was countered with an anti-corrosion coating applied after fabrication. No armor was provided for the pilot, engine or other critical points of the aircraft, and self-sealing fuel tanks, which were becoming common at the time, were not used. This made the Zero lighter, more maneuverable, and the longest range single engine fighter of WWII; which made it capable of searching out an enemy hundreds of kilometres (miles) away, bringing them to battle, then returning hundreds of kilometres back to its base or aircraft carrier. However, that trade in weight and construction also made it prone to catching fire and exploding when struck by enemy rounds.〔Tillman 1979, pp. 5, 6, 96.〕 With its low-wing cantilever monoplane layout, retractable, wide-set conventional landing gear and enclosed cockpit, the Zero was one of the most modern aircraft in the world at the time of its introduction. It had a fairly high-lift, low-speed wing with a very low wing loading. This, combined with its light weight, resulted in a very low stalling speed of well below . This was the main reason for its phenomenal maneuverability, allowing it to out-turn any Allied fighter of the time. Early models were fitted with servo tabs on the ailerons after pilots complained control forces became too heavy at speeds above . They were discontinued on later models after it was found that the lightened control forces were causing pilots to overstress the wings during vigorous maneuvers.〔Yoshimura 1996, p. 108.〕 It has been claimed that the Zero's design showed clear influence from American fighter aircraft and components exported to Japan in the 1930s, and in particular the Vought V-143 fighter. Chance Vought had sold the prototype for this aircraft and its plans to Japan in 1937. Eugene Wilson, President of Vought, claimed that when shown a captured Zero in 1943, he found that "There on the floor was the Vought V 142 or just the spitting image of it, Japanese-made," while the "power-plant installation was distinctly Chance Vought, the wheel stowage into the wing roots came from Northrop, and the Japanese designers had even copied the Navy inspection stamp from Pratt & Whitney type parts."〔Fernandez 1983, pp. 107–108.〕 While the sale of the V-143 was fully legal,〔〔Angelucci and Bowers 1987, p. 436.〕 Wilson later acknowledged the conflicts of interest that can arise whenever military technology is exported.〔 Counterclaims maintain that there was no significant relationship between the V-143 (which was an unsuccessful design that had been rejected by the U.S. Army Air Corps and several export customers) and the Zero, with only a superficial similarity in layout. Allegations about the Zero being a copy have been mostly discredited.〔〔''Air International'' October 1973, pp. 199–200.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mitsubishi A6M Zero」の詳細全文を読む スポンサード リンク
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