Mitsubishi A6M Reisen
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The standard engine fitted to the Model 22 was the 1130hp
Nakajima NK1F Sakae 21 fourteen-cylinder radial equipped with a two-speed
supercharger. The official RNZAF report from the Engineer Officer at
Hobsonville quotes this aircraft as being fitted with the Sakae 12 motor.
This model, normally fitted to the A6M2 model, was lighter, shorter
and less powerful than the Sakae 21. Fitting of a Sakae 12 to an A6M3
like NZ6000 would have posed weight distribution and center of gravity
problems on the aircraft.
N - manufacturer (Nakajima) K = air cooled 1 = sequence number within given class of engines F = version of the engine (i.e. 6th version)When put into production, the engine was known by a name followed by a model number, in this case Sakae (Prosperity) 21.
The Japanese Army had a different designation system. and the Ministry of Munitions later devised a joint system for both Navy and Army engines. In this system, the Sakae 21 became known as the Ha-75 21:
Ha = abbreviation for Hatsudoki (engine) 3 = air cooled, double row, 14-cylinder radial 5 = 130mm bore. 150mm stroke 21 = Model number for specific variant in Ha-35 series