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Nakajima A7N - Akagi Fighter Squadron, 1941

Even before the Mitsubishi A5M had entered service in early 1937 with the Imperial Japanese Navy (IJN) they started looking for its eventual replacement. By the late summer of 1937 the IJN issued their bold requirements to Nakajima and Mitsubishi for a new carrier-based fighter aircraft calling for manoeuverability at least equal to that of the A5M but with a top speed of 500 km/h at 4,000m with a climb to 3,000m in less than 9.5 minutes. Furthermore they asked for an endurance of two hours at normal power but with a staggering endurance of at least six hours at an economical cruising speed. Both firms started preliminary design work towards the end of 1937 but Mitsubishi soon gained the upper hand when Nakajima's team considered the bold requirements to be unachievable and withdrew from the competition in January 1938. 

Much to the chagrin of Mitsubishi's chief designer, Jiro Horikoshi, Nakajima were immediately allowed to rejoin the competition with a revised design called the A7N featuring the top-secret "super duralumin" aluminium alloy (a key feature of the Mitsubishi A6M design) which had been under development by Sumitomo Metal Industries since 1936. This alloy was lighter, stronger and more ductile than other alloys used at the time but it was prone to corrosive attack requiring specially developed anti-corrosion coatings applied after fabrication. Mitsubishi had planned the use of super duralumin allied to their own anti-corrosion coatings and it was later revealed that the IJN had passed these two commercial advantages onto Nakajima in order to get two superior competing designs. With an initial time advantage Mitsubishi developed their A6M design into the highly succesful Type 0 'Zero-sen' carrier fighter which entered service with the 12th Rengo Kōkūtai in July 1940 and were soon in action scoring their first air-to-air victories shooting down Soviet-built Polikarpov I-15s and I-16s of the Chinese Nationalist Air Force without loss to themselves. 

But the IJN could see the potential of Nakajima's design and in May 1938 they awarded Nakajima a production order for 300 aircraft. During the remainder of 1938 Nakajima worked on their revised A7N design and introduced a further refinement by incorporating an oversized propeller spinner whose outside diameter was the same as the engine cowl with the spinner having a small hole at it's centre allowing cooling air to be directed through ductwork in the spinner to blow rearwards along the cylinder heads around the circumference of the radial engine (the hottest area of any air-cooled radial engine). This enabled Nakajima to give the A7N a highly streamlined front fuselage resulting in a useful speed advantage over the draggier engine installation of the A6M. For the carried-based role the A7N featured a wide-tracked, inwards-retracting landing gear (designed to withstand a sink rate of 4.5 meters per second) with hydraulic wheel brakes. Nakajima's chosen powerplant for the A7N was their own NK1E Sakae 31 rated at 1,130hp and boosted to 1,210 hp with water-methanol injection and this was to prove an exceptionally rugged powerplant. Unlike the heavily framed 'greenhouse' canopy of the Mitsubishi A6M, Nakajima designed the A7N to have excellent all-round vision thanks to a vacuum-formed 'bubble' canopy combined with an optically flat three-panel windscreen. 

Development continued during 1939 with the prototype A7N taking to the air on August 31st, 1939 - this being the first of a total of six A7N prototypes. Nakajima began production of the A7N at its Koizumi plant in Gunma Prefecture in September 1940 and the aircraft entered service with the 13th Rengo Kōkūtai in February 1941. Later in the year, A7N's were embarked aboard the IJN carriers Akagi and Kaga taking part in the infamous attack on Pearl Harbor on December 7th, 1941 as part of the third group of the 'first wave' attacks specifically tasked with the destruction of aircraft at Ford Island, Hickam Field, Wheeler Field, Barber's Point and Kaneohe.

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If it weren't that everybody knows that this plane is originally a german one, it could be easily assumed, from my point of view, that this could the Zero's brother. Very well done!

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Holy! Shit! Spinners! There's outdoing yourself, and then there's OUTDOING yourself! Calling this fantastic doesn't do it justice!

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