Changes

Development by Mitsubishi started in 1937 whilst its predecessor - the [[Type 96 Fighter|Mitsubishi A5M]] (''Type 96 Carrier-based Fighter) -'' was entering service as the Imperial Japanese Navy began to consider its eventual replacement. Specification ''12-shi'' was sent to Nakajima and Mitsubishi, which both initiated early development phases whilst waiting more complete requirements.  

Development by Mitsubishi started in 1937 whilst its predecessor - the [[Type 96 Fighter|Mitsubishi A5M]] (''Type 96 Carrier-based Fighter) -'' was entering service as the Imperial Japanese Navy began to consider its eventual replacement. Specification ''12-shi'' was sent to Nakajima and Mitsubishi, which both initiated early development phases whilst waiting more complete requirements.  

Assessing the performance and experiences of the then service-fighter A5M, the IJN's final requirements were for the fighter to reach speeds of 600km/h and climb to 3km in 3.5 minutes while being able to operate for as much as 6-8 hours at cruise with drop-tanks. Equipment was to include a complete radio and armament of twin 20mm cannons plus twin 7.7mm machine guns as well as 60kg of bombs. Maneuverability was to be at least equal to the A5M with a wingspan less than 12m so that it could be fielded on aircraft carriers. On top of those lofty specifications, the ''Type 12'' had to use available engines, a significant limitation.

Assessing the performance and experiences of the then service-fighter A5M, the IJN's final requirements were for the fighter to reach speeds of 600km/h and climb to 3km in 3.5 minutes while being able to operate for as much as 6-8 hours at cruise with drop-tanks. Equipment was to include a complete radio and armament of twin 20mm cannons plus twin 7.7mm machine guns as well as 60kg of bombs. Maneuverability was to be at least equal to the A5M with a wingspan less than 12m so that it could be fielded on aircraft carriers. On top of those lofty specifications, ''Specification 12'' had to use available engines, a significant limitation.

Nakajima's engineering team deemed the ''Type 12'' specification impossible and resigned from the competition. Jiro Horikoshi, developer of the A5M (and subsequently, the [[Reppuu (Strong Gale)|A7M]]) thought it was feasible only with an aircraft as light as possible. Every possible weight-reduction measure was incorporated into the A6M, including Sumitomo Metal's new top-secret 7075 aluminum alloy, "Extra Super Duralumin". Armor for the pilot, engine or other critical points was dropped, as were self-sealing fuel tanks. It had a cantilever low-wing layout, retractable landing gear and enclosed cockpit.  

Nakajima's engineering team deemed ''Specification 12''<nowiki/><nowiki>'s targets impossible and resigned from the competition. Jiro Horikoshi, developer of the A5M (and subsequently, the </nowiki>[[Reppuu (Strong Gale)|A7M]]) thought it was feasible only with an aircraft as light as possible. Every possible weight-reduction measure was incorporated into the A6M, including Sumitomo Metal's new top-secret 7075 aluminum alloy, "Extra Super Duralumin". Armor for the pilot, engine or other critical points was dropped, as were self-sealing fuel tanks. It had a cantilever low-wing layout, retractable landing gear and enclosed cockpit.  

The A6M1 prototype, powered by a 780hp Mitsubishi ''Zuisei 13 ''engine, passed its testing in a remarkably short period and was ordered into service as the A6M1. Shortly after, the A6M2 incorporated an engine change suggested by the Navy to the 700hp Nakajima ''Sakae 12. ''The new prototype so greatly surpassed the original specifications that 15 units were sent to battle in China, where they were untouched by planes that troubled the A5M. These results led the Navy to immediately order the A6M2 into production as the Type 0 Model 11.

The A6M1 prototype, powered by a 780hp Mitsubishi ''Zuisei 13 ''engine, passed its testing in a remarkably short period and was ordered into service as the A6M1. Shortly after, the A6M2 incorporated an engine change suggested by the Navy to the 700hp Nakajima ''Sakae 12. ''The new prototype so greatly surpassed the original specifications that 15 units were sent to battle in China, where they were untouched by planes that troubled the A5M. These results led the Navy to immediately order the A6M2 into production as the Type 0 Model 11.