Kawanishi N1K


The Kawanishi N1K was an Imperial Japanese Navy fighter aircraft which was developed in two variants. The N1K Kyōfū, a floatplane designed to support forward offensive operations where no airstrips were available. The N1K-J Shiden, a land-based version of the N1K. Contemporary pilots and Allied reports praised the N1K-J’s performance, noting its high speed and maneuverability compared with other Japanese fighters of the period.
The improved N1K2-J Shiden Kai made its first flight on 1 January 1944. It carried four 20 mm cannons and used an automatic flap-extension mechanism, operated by a mercury-tilt sensor, to enhance lift during tight turns. These automatically deploying flaps increased wing lift during high-G maneuvers, allowing a tighter turn radius without additional pilot input. Unlike the Mitsubishi A6M Zero, the Shiden Kai could engage late-war allied fighters such as the F6F Hellcat, F4U Corsair, and P-51 Mustang on equal terms.

Design and development

Kawanishi's N1K was originally built as a single pontoon 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 longer a need for a fighter to fulfill this role. The Navy's requirements for this fighter were nearly impossible to achieve for a float plane, and the expected protracted development period led Nakajima to develop an interim float plane fighter based on the Zero, the Nakajima A6M2-N. In the end, the Kyofu only saw limited service, mostly in Southeast Asia. A number were flown out of Ambon and the Aru Islands in the Moluccas, while some were stationed at Penang Island, off the Malayan peninsula. They were also used in the Battle of Okinawa. Towards the end of the war, Kyōfū were also used in the homeland defense role, operating from Lake Biwa by the Sasebo Air Corps and the Ōtsu Air Corps.
The N1K was powered by the Mitsubishi MK4C Kasei 13 14-cylinder radial engine. Top speed was ; falling short of the Navy's specified requirement of requirement.

Land-based version

The requirement to carry a bulky, heavy float essentially crippled the N1K against contemporary American fighters. However, in late 1941 Kawanishi engineers had proposed that the N1K could serve as a basis for a fighter variant. A land-based version was produced as a private venture. This version flew on 27 December 1942, powered by a Nakajima NK9A Homare 11 18-cylinder radial engine, replacing the less powerful MK4C Kasei 13 of the N1K-1. The aircraft retained the mid-mounted wing of the floatplane; combined with the large propeller, this necessitated a long, stalky main landing gear. A unique feature was the aircraft's combat flaps that automatically adjusted in response to acceleration, freeing up the pilot's concentration, and reducing the chance of stalling in combat. However, the N1K did have temperamental flight characteristics that required an experienced touch at the controls.
The Nakajima Homare was powerful but had been rushed into production before it was sufficiently developed and proved troublesome. Another problem was landing gear failure due to poor heat treatment of the wheels. 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 Shidens first test flight, a complete redesign began. The N1K2-J 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 a shorter, conventional undercarriage. The fuselage was lengthened and the tail redesigned. The production of the entire aircraft was simplified: over a third of the parts used in the previous Shiden could still be used in its successor, while construction used fewer critical materials. The N1K2-J was approximately lighter, while faster and more reliable than its predecessor. The Homare engine was retained, even though reliability problems persisted, as no alternative was available. A prototype of the new version flew on 1 January 1944. After completing Navy trials in April, the N1K2-J was rushed into production. This variant was named the "Shiden Kai"" with Kai meaning modified.

Operational history

The N1K1-J Shiden entered service in early 1944. The N1K1-J and the N1K2 Shiden Kai released later that year were among the rare Japanese aircraft that offered pilots an even chance against late-war American designs, such as the F6F Hellcat and the F4U Corsair, and could be a capable weapon in the hands of an ace. In February 1945, Ensign Kaneyoshi Muto, flying an N1K2-J as part of a mixed formation of at least ten Japanese aircraft, faced seven U.S. Navy Hellcat pilots from squadron VF-82 in the sky over Japan; the formation shot down four Hellcats with no loss to themselves. After the action, Japanese propagandists fabricated a story in which Muto was the sole airman facing twelve enemy aircraft.
The N1K1-J aircraft were used very effectively over Formosa, the Philippines, and, later, Okinawa. Before production was switched to the improved N1K2-J, 1,007 aircraft, including prototypes, were produced. Because of production difficulties and damage done by B-29 raids on factories, only 415 of the superior N1K2-J fighters were produced.
The N1K2-J Shiden Kai proved to be a superior dogfighting aircraft than the earlier IJN fighters, but still slower than allied types and less rugged. Having adequate speed, the Shiden Kai offered pilots an agile aircraft with a roll rate of 82°/sec at 386 km/h, and carried four 20 mm cannons in the wings. As a bomber interceptor, the N1K2-J fared less well, hampered by a poor rate of climb and reduced engine performance at high altitude.

343 Kōkūtai

The N1K2-J Shiden Kai was an advanced fighter offered in limited quantities. As a result, the planes were distributed to elite naval fighter units such as 343 Kōkūtai, constituted on 25 December 1944 and commanded by Minoru Genda. ''This unit was highly successful for its very brief history.''

Variants

;N1K1 Kyōfū
  • N1K1 Kyōfū: Standard type as floatplane, which was used from early 1943, with Mitsubishi MK4C Kasei 13 engine.
  • N1K2 Kyōfū Kai: Reserved name for an intended model with larger engine, not built.
;N1K1-J Shiden
  • N1K1-J Prototypes: development of fighter hydroplane N1K1 Kyōfū, with 1,820 hp Homare 11 engine.
  • N1K1-J Shiden Model 11: Navy Land Based Interceptor, first production model with 1,990 hp Homare 21 engine and revised cover, armed with two 7.7 mm Type 97 machine guns and two 20 mm Type 99 cannons. Modified total-vision cockpit.
  • N1K1-Ja Shiden Model 11A: without frontal 7.7 mm Type 97s, with only four 20 mm Type 99s in wings.
  • N1K1-Jb Shiden Model 11B: similar to Model 11A but capable of carrying two 250 kg bombs, with revised wing weapons mounts.
  • N1K1-Jc Shiden Model 11C: definitive fighter-bomber version, derived from Model 11B. Four bomb racks under wings.
  • N1K1-J Kai a Experimental version with auxiliary rocket. One Model 11 conversion.
  • N1K1-J Kai b Conversion for dive bombing. One 250 kg bomb under belly and six rockets under wings.
;N1K2-J Shiden-Kai
  • N1K2-J Prototypes: N1K1-Jb redesigned. Low wings, engine cover and landing gear modified. New fuselage and tail, 8 built.
  • N1K2-J Shiden Kai Model 21: Navy Land Based Interceptor, first model of series with a Nakajima Homare 21 engine.
  • N1K2-Ja Shiden Kai Model 21A: Fighter Interceptor version: 2,000 hp Homare 21-18 engine with a low wing and larger prop design with four 250 kg ground bombs. Fixed problem with teething pains of N1K2 J at high altitude.
  • N1K2-K Shiden Kai Rensen 1, Model A: Fighter Trainer, modified from N1K-J Series with two seats, operative or factory conversions.
;Further variants
  • N1K3-J Shiden Kai 1, Model 31: Prototypes: Engines displaced to ahead, two 13.2 mm Type 3 machine guns in front, 2 built.
  • N1K3-A Shiden Kai 2, Model 41: Prototypes: Carrier-based version of N1K3-J, 2 built.
  • N1K4-J Shiden Kai 3, Model 32: Prototypes: 2,000 hp Homare 23 engine, 2 built.
  • N1K4-A Shiden Kai 4, Model 42: Prototype: Experimental conversion of N1K4-J example with equipment for use in carriers, 1 built.
  • N1K5-J Shiden Kai 5, Model 25: High-Altitude Interceptor version with Mitsubishi HA-43 with 2,200 takeoff hp, project only.

    Production

  • First prototype completed in April 1942, and made its maiden flight on 6 May 1942.
  • Pre-production started with eight prototypes and service trials aircraft completed from August 1942 to December 1942, and with a further five, in the following year.
  • Pre-production started with nine prototypes and service trials aircraft completed from July 1943 to Aug. 1943.
  • Pre-production started with eight prototypes and service trials aircraft completed from Dec. 1943 to May. 1944.

    Operators

  • Imperial Japanese Navy Air Service

    Surviving aircraft

All four surviving Shiden Kai aircraft are now displayed in American and Japanese museums, while all three surviving Kyofu aircraft are displayed/stored in American museums.
One N1K2-J is at the National Naval Aviation Museum at Naval Air Station Pensacola, Florida.
The second N1K2-Ja, a fighter-bomber variant equipped with wing mounts to carry bombs, is on display in the Air Power gallery at the National Museum of the United States Air Force, at Wright-Patterson Air Force Base near Dayton, Ohio. This aircraft was displayed outside for many years in a children's playground in San Diego, suffering considerable corrosion, and had become seriously deteriorated. In 1959 it was donated to the Museum through the cooperation of the San Diego Squadron of the Air Force Association.
The third example is owned by the National Air and Space Museum but was restored by the Champlin Fighter Museum at Falcon Field, Mesa, Arizona, in return for the right to display the aircraft at Falcon Field for 10 years after restoration. It currently is on display at the National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Virginia.
The fourth authentic Shiden-Kai is displayed in a local museum at Nanreku Misho Koen in Ehime Prefecture, Shikoku, Japan. This aircraft is known to be from the 343rd Kōkūtai, as the unit flew sorties in the area, but the tail code is unknown as it was partially restored from a corroded wreck recovered from the sea. After an aerial battle on July 24, 1945, its pilot ditched the aircraft in the waters of the Bungo Channel, but he was never found; by the time of the aircraft's recovery from the seabed on July 14, 1979, he could be identified only as one of six pilots from the 343rd squadron who disappeared that day. Photographs of the six—including Takashi Oshibuchi, commander of the 701 Hikōtai, and Kaneyoshi Muto—are displayed under the aircraft engine. In 2019, the aircraft was restored to non-flying condition.
N1K1 Kyōfū is in storage at the National Air and Space Museum's Paul E. Garber Preservation, Restoration, and Storage Facility in Suitland, Maryland.
N1K1 Kyōfū is located on display at the National Museum of the Pacific War in Fredricksburg, Texas.
N1K1 Kyōfū, formerly displayed at Naval Air Station Joint Reserve Base Willow Grove, Horsham Township, Montgomery County, Pennsylvania, stored at the National Naval Aviation Museum in Pensacola, Florida. Now being restored by American Aero Services, New Smyrna Beach, Florida, for the American Heritage Museum in Stow, Massachusetts.