Kawanishi N1K - Design and Development

Design and Development

Kawanishi's N1K was originally built as a floatplane fighter to support forward offensive operations where no airstrips were available, but by 1943 when the aircraft entered service, Japan was firmly on the defensive, and there was no more need for a fighter to fulfill this role.

The requirement to carry a bulky, heavy float essentially crippled the N1K against contemporary American fighters. Kawanishi engineers, however, had proposed in late 1941 that the N1K would be the basis of a formidable land-based fighter too, and a land-based version was produced as a private venture by the company. This version flew on 27 December 1942, powered by a Nakajima NK9A Homare 11 radial engine, replacing the less powerful Mitsubishi MK4C Kasei 13 of the N1K. The aircraft retained the mid-mounted wing of the floatplane, and combined with the large propeller necessitated a long, stalky main landing gear. A unique feature was the aircraft's automatic combat flaps that adjusted automatically based on acceleration, freeing up the pilot from having to do this and reducing the chance of stalling in combat. The N1K did have a vice: If handled roughly, it could easily enter an unrecoverable spin.

The Nakajima Homare was powerful, but had been rushed into production before it was sufficiently developed, and proved troublesome. Another problem was that, due to poor heat treatment of the wheels, their failure upon landing would often result in the landing gear being simply ripped off. It was reported that more "Georges" were lost to this than to Allied forces. Apart from engine problems and the landing gear the flight test program showed that the aircraft was promising. Prototypes were evaluated by the Navy, and since the aircraft was faster than the Zero and had a much longer range than the Mitsubishi J2M Raiden, it was ordered into production as the N1K1-J, the -J indicating a land-based fighter modification of the original floatplane fighter.

Only four days after the Shiden's first test flight, a complete redesign was begun, the N1K2-J. The new design addressed the N1K1-J's major defects, primarily the mid-mounted wing and long landing gear. The wings were moved to a low position, which permitted the use of shorter, conventional undercarriage, the fuselage was lengthened, the tail redesigned, and the whole aircraft was made much simpler to produce, with over a third of the parts of the Shiden. Construction materials involved the use of non-critical materials. The redesign was approximately 250 kg (550 lb) lighter, faster and more reliable than the previous N1K1 version. Since there was no alternative, the Homare engine was retained, even though its reliability problems had not been fully corrected. A prototype flew on 1 January 1944 and after completing Navy trials in April, the N1K2-J was rushed into production. The variant was named the "Shiden-Kai" (紫電改), Kai standing for Modified.