Category Archives: Imperial Navy Air Force

Japan

Heavy Bomber, Torpedobomber, Reconnaissance

Kawanishi H8K2 “Type 2 Flying Boat, Model 12“, (Nishiki Hikōtei 12-gata), (“Emiliy”), 901st. Naval Air Corps_Combined Maritime Escort Force, (Hasegawa)

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TYPE: Long-range Maritime Reconnaissance and Bomber Flying Boat

ACCOMMODATION: Crew of ten

POWER PLANT: Four Mitsubishi MK4Q “Kasei 22” radial engines, rated at 1,380 hp each

PERFORMANCE: 290 mph at 16,400 ft

COMMENT: The Kawanishi H8K “ Type 2 Large-sized Flying Boat) was an Imperial Japanese Navy flying boat used during WW II for maritime patrol duties. The Allied reporting name for the type was “Emily”.
At the same time the type’s predecessor, the Kawanishi H6K, was going into service in 1938 the Navy ordered the development of a larger, longer-ranged patrol aircraft under the designation “Navy Experimental 13-Shi Large-size Flying Boat”. The result was a large, shoulder-winged design that is widely regarded as the best flying boat of the war. Despite this, initial development was troublesome, with the prototype displaying terrible handling on the water. Deepening of the hull, redesigning of the planing bottom and the addition of spray strips under the nose rectified this. Two further prototypes— actually pre-production aircraft— joined the development program in December 1941. The IJNAF accepted the first production version as the H8K1, “Navy Type 2 Flying Boat, Model 11”, of which 14 would be built.
The H8K1 entered production in 1941 and first saw operational use on the night of 4 March 1942 in a second raid on Pearl Harbor. Since the target lay out of range for the flying boats, this audacious plan involved a refueling by submarine, some 900 km north-west of Hawaii. Two planes from the Yokohama Kokutai (Naval Air Corps) attempted to bomb Pearl Harbor, but, due to poor visibility, did not accomplish any significant damage.
Six days after the second Pearl Harbor raid one of the “Emily’s” was sent on a daylight photo-reconnaissance mission of Midway Atoll. It was intercepted by radar directed Brewster F2A-3 “Buffalo” fighters of Marine Corps squadron VMF-221 and shot down.
After serving as an engine test bed for the Kasei 22 powered H8K2, the original H8K1 experimental aircraft was again modified as the prototype for a transport version of the H8K series. The deep hull made possible the installation of two decks, the lower deck extending from the nose to the rear hull step and the upper extending from the wing centre-section to the rear of the hull. Accommodation was provided for either twenty-nine passengers or sixty-four troops, the armament was reduced to one flexible 13mm Type 2 machine gun in the nose turret and one 20 mm Type 99 Model 1 cannon in the tail turret. A total of thirty-six H8K-2L transport flying boat “Seiku” (“Clear sky) were built between 1943 and 1945 and exclusively operated by Naval transport units.
An improved version of Kawanishi H8K2 “Type 2 Flying Boat, Model 12” (Nishiki Hikōtei 12-gata) soon appeared, and it’s extremely heavy defensive armament earned it deep respect among Allied aircrews. The H8K2 was an upgrade over the H8K-1, having more powerful engines, slightly revised armament, and an increase in fuel capacity. They were used on a wide range of patrol, reconnaissance, bombing, and transport missions throughout the Pacific war. In mid 1943, many aircraft were equipped with Mark IV Model 1 ASV radar. This was to be the definitive variant, with 112 aircraft produced.
Even though far fewer Kawanishi H8Ks were built than contemporary British Short “Sunderlands” or American Consolidated PBY “Catalinas”, the Japanese flying-boat emerged from conflict as the most outstanding water-based combat aircraft of the second World War (Ref.: 1, 24).

Fighter-Torpedobomber

Aichi B7A1 ‘Ryusei’ (“Shooting Star”, “Grace”), (Fujimi Models)

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TYPE: Carrier-borne torpedo- and dive bomber

ACCOMMODATION: Crew of two

POWER PLANT: One Nakajima NK9B “Homare 11” radial engine, rated at 1,560 hp at 21,000 ft

PERFORMANCE: 367 mph

COMMENT: The Aichi B7A “Ryusei” (“Shooting Star”, Allied reporting name “Grace”) was a large and powerful carrier-borne torpedo-dive bomber produced by Aichi Kokuki KK for the Imperial Japanese Navy Air Service during the Second World War. Built in only small numbers and deprived of the aircraft carriers it was intended to operate from, the type had little chance to distinguish itself in combat before the war ended in August 1945.
The B7A “Ryusei” (originally designated AM-23 by Aichi) was designed in response to a 1941 16-Shi requirement issued by the Imperial Japanese Navy Air Service for a carrier attack bomber that would replace both the Nakajima B6N “Tenzan” torpedo plane and the Yokosuka D4Y “Suisei” dive bomber in IJN service. It was intended for use aboard a new generation of “Taihō”-class aircraft carriers, the first of which was laid down in July 1941. Because the deck elevators on the “Taihōs” had a larger square area than those of older Japanese carriers, the longstanding maximum limit of 11 m (36 ft) on carrier aircraft length could now be lifted.
The Aichi’s designers chose a mid-wing arrangement for the B7A to provide for an internal bomb-bay and to ensure enough clearance for the plane’s 3.5 m four-bladed propeller. This in turn necessitated the adoption of an inverted gull wing, reminiscent of the Vought F4U “Corsair”, in order to shorten the length of the main landing gear. The wing featured extendable ailerons with a ten-degree range of deflection, enabling them to act as auxiliary flaps. Dive brakes were fitted underneath just outboard of the fuselage. The B7A’s outer wing panels were designed to fold upwards hydraulically for carrier stowage, reducing its overall span from 14.4 m to approximately 7.9 m.
Selection of a power plant was dictated by the Japanese Navy which requested that Aichi design the aircraft around the 1,825 hp Nakajima NK9C “Homare 12” 18-cylinder two-row air-cooled radial engine. This was expected to become the Navy’s standard aircraft engine in the 1,800 hp to 2,200 hp range.  The B7A had a weight-carrying capacity stemming from its requirements, resulting in a weapons load no greater than its predecessors. The presence of an internal bomb bay with two high-load-capability attachment points allowed the aircraft to carry two 250 kg or six 60 kg bombs. Alternatively, it could carry a single externally mounted Type 91 torpedo, weighing up to 848 kg.
Defensive armament initially consisted of two 20mm Type 99 Model 2 cannons in the wing roots and one flexible 7.92mm Type 1 machine-gun mounted in the rear cockpit. Later production models of the B7A2 featured a 13mm Type 2 machine-gun in place of the 7.92mm gun.
Despite the plane’s weight and size, it displayed fighter-like handling and performance, besting the version of the Mitsubishi A6M “Zero” in service at the time. It was fast and highly maneuverable.
Given the codename “Grace” by the Allies, the B7A1 first flew as a prototype in May 1942, but teething problems with the experimental NK9C “Homare” engine and necessary modifications to the airframe meant that the type did not enter into production until two years later in May 1944. Nine prototype B7A1s (the second prototype is shown here)  were built and were progressively modified to eradicate minor airframe and equipment problems.
In April 1944 an improved engine version, the 1,825 hp “Homare 12”, became available and powered by this engine the aircraft was finally placed in production as the Aichi B7A2 “Ryusei” (Ref.: 24).

Fighter, Fighterbomber

Mitsubishi A6M5c ‘Rei-sen’ (“Zero”, “Zeke”), (Hasegawa)

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TYPE: Carrier-borne fighter, fighter-bomber

ACCOMMODATION: Pilot only

POWER PLANT: One Nakajima NK1F “Sakae 21” radial engine, rated at 1,100 hp at 9,350 ft

PERFORMANCE: 351 mph at 19,685 ft

COMMENT: The Mitsubishi A6M “Zero” was the best known Japanese warplane of WW II. A6M “Zeros” were predominantly used by the Imperial Japanese Navy Air Service (IJN) on aircraft carriers, and also by its land-based fighter units. At the start of the Pacific War in 1941, the A6M constituted about 60% of the IJN fighter force. It took part in carrier operations throughout much of the Pacific Ocean, as well as over the northeast Indian Ocean
The Mitsubishi A6M “Zero” is a long-range fighter aircraft formerly manufactured by Mitsubishi Aircraft Company. Officially, the A6M was designated as the Mitsubishi Navy Type 0 carrier fighter (“Rei-shiki-kanjō-sentōki”), or the Mitsubishi A6M “Rei-sen”. The A6M was usually referred to by its pilots as the “Reisen” (Zero fighter), “0” being the last digit of the Imperial Year 2600 (1940) when it entered service with the Imperial Navy. The official Allied reporting name was “Zeke”, although the use of the name “Zero” was later adopted by the Allies as well.
The “Zero” was considered the most capable carrier-based fighter in the world when it was introduced early in WW II, combining excellent maneuverability and very long range. The IJN also frequently used it as a land-based fighter.
With its low-wing cantilever monoplane layout, retractable, wide-set conventional landing gear and enclosed cockpit, the “Zero” was one of the most modern carrier based aircraft in the world at the time of its introduction. It had a fairly high-lift, low-speed wing with very low wing loading. This, combined with its light weight, resulted in a very low stalling speed of well below 69 mph. This was the main reason for its phenomenal maneuverability, allowing it to out-turn any Allied fighter of the time.
The “Zero” quickly gained a fearsome reputation. Thanks to a combination of unsurpassed maneuverability — even when compared to other contemporary Axis fighters — and excellent firepower, it easily disposed the motley collection of Allied aircraft sent against it in the Pacific in 1941. It proved a difficult opponent even for the British Supermarine “Spitfire”.  Although not as fast as the British fighter, the “Zero” could out-turn the “Spitfire” with ease, sustain a climb at a very steep angle, and stay in the air for three times as long. In early combat operations, the “Zero” gained a legendary reputation as a dogfight achieving an outstanding kill ratio of 12 to 1, but by mid-1942 a combination of new tactics and the introduction of better equipment enabled Allied pilots to engage the “Zero” on generally equal terms. By 1943, due to inherent design weaknesses and an inability to equip it with a more powerful aircraft engine, the “Zero” gradually became less effective against newer Allied fighters. By 1944, with opposing Allied fighters approaching its levels of maneuverability and consistently exceeding its firepower, armor, and speed, the A6M had largely become outdated as a fighter aircraft. However, due to design delays and production difficulties, which hampered the introduction of newer Japanese aircraft models, the “Zero” continued to serve in a front line role until the end of the war in the Pacific. During the final phases, it was also adapted for use in Kamikaze operations.
Japan produced more “Zeros” than any other model of combat aircraft during the war. When the war in the Pacific Area of Action ended, 10,939 aircraft have been built by Mitsubishi Jukogyo K.K. and Nakajima Hikoki K.K. in four major variants A6M2, A6M3, A6M5, and A6M8, each variant including several subtypes. Nakajima built a float-plane variant, the Nakajima A6M2-N, Allied reporting name “Rufe”.
The Mitsubishi A6M5c, Model 52 Hei, featured an armament change: One 13.2 mm Type 3 machine gun was added in each wing outboard of the cannon, and the 7.7 mm gun on the left side of the cowl was deleted. Four racks for rockets or small bombs were installed outboard of the 13 mm gun in each wing. Engine changed to a Nakajima NK1F “Sakae21” although some sources state that the A6M5c had a more powerful “Sakae 31” engine. In addition, a 55 mm thick piece of armored glass was installed at the headrest and an 8 mm thick plate of armor was installed behind the seat. The mounting of the central 300 l (79 US gal) drop tank changed to a four-post design. Wing skin was thickened further. The first of this variant was completed in September 1944 (Ref.: 24).

Fighter, Projects

Kugisho High-Speed Aircraft Project with NK-1B (Unicraft, Resin)

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TYPE: Interceptor, fighter. Project

ACCOMMODATION: Pilot only

POWER PLANT: One Nakajima NK-1B “Sakae” radial engine, rated at 1,100 hp

PERFORMANCE: No data available

COMMENT: On 26 April 1939, a German Messerschmitt Me 209 V1 set a new world speed record of almost 469 mph. This relative small Me 209 was a completely new aircraft and not to mistake for a replacement of the Messerschmitt Me 109, entering service with the Luftwaffe at the same time. Its only purpose was to set a new speed record.
Impressed by that speed the Imperial Japanese Navy Air Force authorized the Yokosuka Naval Air Technical Arsenal, Yokosuka also known as Kaigun Koku Gijutsusho or Kugisho to propose several designs of similar aircraft. In a complete reversal from previous Japanese Navy requirements priority was given speed, rate of climb, and maneuverability.
One design was built around a Nakajima NK1 “Sakae” radial engine, one of the most powerful engines available in Japan at that time. Another design proposed by Kugisho was the Kugisho (Kugisho High-Speed Aircraft Project with DB 601A), powered by a Kawasaki Ha-40 liquid-cooled engine derived from the German Daimler-Benz DB 601A. A more powerful variant of this engine was installed in the world record-breaking Messerschmitt Me 209 V1.
Although calculations and designs were in an advanced stage none of the Kugisho projects were realized
Noteworthy is the fact that the Imperial Japanese Army Air Force had similar projects, e. g. the Kawasaki Ki-60.

Fighterbomber

Aichi M6A “Seiran” (“Mountain Haze”), 631st Kokutai, (MPM Models)

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TYPE: Submarine-launched attack floatplane

ACCOMMODATION: Crew of two

POWER PLANT: One Aichi “Atsuka” Type 31 liquid-cooled engine, rated at 1,400 hp

PERFORMANCE: 295 mph at 17,060 ft

COMMENT: To equip the I-400 class submarine aircraft carriers, the Imperial Japanese Navy Air service requested for an attack aircraft with a range of 1,000 mi and a speed of 345 mph. Aichi aircraft company proposed a design on the basis of the Yokosuka D4Y1 “Suisei” that Aichi was already manufacturing under license. The D4Y1 was a relatively small single-engine carrier dive bomber with exceptionally clean lines and high performance. Detailed engineering studies commenced in an effort to modify the “Suisei” for use aboard the I-400 submarines but the difficulties in doing so were eventually judged insurmountable and a completely new design was initiated.
Aichi’s final design, designated M6A1, was a two-seat, low-winged monoplane powered by an Aichi “Atsuka” engine, a license-built copy of the German Daimler-Benz DB 602  liquid-cooled engine. The aircraft was fitted with detachable twin floats to increase its versatility. If conditions permitted, these would allow the aircraft to alight next to the submarine, be recovered by crane and then re-used. The floats could be jettisoned in flight to increase performance or left off altogether for one-way missions. The “Seiran’s” wings rotated 90 degrees and folded hydraulically against the aircraft’s fuselage with the tail also folding down to allow for storage within the submarine’s 11 ft diameter cylindrical hangar.
As finalized, each I-400 class submarine had an enlarged watertight hangar capable of accommodating up to three M6A1s. The “Seirans” were to be launched from an 85 ft compressed-air catapult mounted on the forward deck. A well-trained crew of four men could roll a “Seiran” out of its hangar on a collapsible catapult carriage, attach the plane’s pontoons and have it readied for flight in approximately 7 minutes.
The first of eight prototypes was completed in October 1943, commencing flight testing in November that year. A problem with overbalance of the auxiliary wings was eventually solved by raising the height of the tail fin. Further testing was sufficiently successful for production to start in early 1944.  Owing to the reduced carrier submarine force, production of the “Seiran” was halted, with a total of 28 completed. In mid 1945, it was planned to attack the American base at Ulithi Atoll where forces, including aircraft carriers, were massing in preparation for attacks on the Japanese Home Islands. The flotilla departed Japan on 23 July 1945 and proceeded towards Ulithi. On 16 August, the flagship I-401 received a radio message from headquarters, informing them of Japans surrender and ordering them to return to Japan. All six “Seirans” on board the two submarines, having been disguised for the operation as American planes in violation of the laws of war, were catapulted into the sea with their wings and stabilizers folded (for the  submarine I-401) or pushed overboard (for the submarine I-400) to prevent capture (Ref.: 24).

Noteworthy is the fact that the German Marine Luftwaffe made similar attempts for submarine-borne aircraft, e. g. the Arado Ar 231.

Nightfighter, Reconnaissance

Nakajima J1N1 C-Kai ‘Gekko’_251st Kokutai (Fujimi)

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TYPE: Reconnaissance aircraft, night fighter

ACCOMMODATION: Crew of two

POWER PLANT: Two Nakajima NK1F “Sakae 21” air-cooled radial engine, rated at 1,130 hp each

PERFORMANCE: 315 mph at 19,160 ft

COMMENT: The Nakajima J1N1 “Gekko” (“Moonlight”) was a twin-engine aircraft used by the Japanese Imperial Navy during WW II and was used  for reconnaissance, night fighter and “Kamikaze” missions. The first flight took place in May 1941. It was given the Allied reporting name “Irving”, since the earlier reconnaissance version the Nakajima J1N1, was mistaken for a fighter.
In mid-1938 the Japanese Imperial Navy requested a twin-engine fighter designed to escort the principal bomber used at the time, Mitsubishi G3M “Nell”. The operating range of the standard Navy fighter, the Mitsubishi A5M “Claude”, was only 750 m), insufficient compared with the 2,730 mi of the G3M. Moreover, at the time, the potential of the Mitsubishi A6M “Zero”, then still under development, remained to be evaluated, stressing the need for a long-range escort fighter, much as the German Luftwaffe had done with the Messerschmitt Bf (Me) 110 “Zerstörer” (“Destroyer”), introduced the year before.
In March 1939, Mitsubishi and Nakajima began the development of a project 13-Shi. The prototype left the factory in March 1941 equipped with two 1,130 hp Nakajima Sakae 21/22, radial engines. There was a crew of three, and the aircraft was armed with a 20 mm Type 99 cannon and six 7.7 mm Type 97 machine guns. Four of these machine guns were mounted in two rear-mounted powered turrets, the weight of which reduced the performance of the aircraft considerably. Because of the sluggish handling, being used as an escort fighter had to be abandoned. Instead, production was authorized for a lighter reconnaissance variant, the J1N1-C, also known by the Navy designation Navy Type 2 Reconnaissance Plane. One early variant, the J1N1-F, had a spherical turret with one 20 mm Type 99 Model 2 cannon mounted immediately behind the pilot.
In early 1943, Commander Y. Kozono of the 251st Kokutai in Rabaul came up with the idea of installing 20 mm cannons, firing upwards at a 30 degree angle in the fuselage. Against orders of central command, which was skeptical of his idea, he tested his idea on a J1N1-C as a night fighter. The field-modified J1N1-C KAI shot down two Boeing B-17s “Flying Fortress” of 43rd Bomb Group attacking air bases around Rabaul on 21 May 1943.
The Navy took immediate notice and placed orders with Nakajima for the newly designated J1N1-S night fighter design. This model was christened the Model 11 “Gekko” (“Moonlight”). It had a crew of two, eliminating the navigator position. Like the J1N1 KAI, it had twin 20 mm Type 99 Model 1 cannon firing upward in a 30° upward angle, but added a second pair firing downward at a forward 30° angle, allowing attacks from above or below. This arrangement was effective against B-17 “Flying Fortress” bombers and Consolidated B-24 “Liberators”, which usually had Sperry ball turrets for ventral defense. The “Gekko’s” existence was not quickly understood by the Allies, who assumed the Japanese did not have the technology for night fighter designs. Early versions had nose searchlights in place of radar. Later models, the J1N1-Sa Model 11a, omitted the two downward-firing guns and added another 20 mm cannon to face upward as with the other two. Other variants without nose antennae or searchlight added a 20 mm cannon to the nose. Many “Gekkos” were also shot down or destroyed on the ground. A number of “Gekkos” were relegated to Kamikaze attacks, using 250 kg bombs attached to the wings. A total of 479 Nakajima J1N1 “Gekkos” were built before the war in the Pacific area was ended (Ref.: 24).

Fighter, Projects

Kayaba “Katsuodori” (“Booby Gannet”), (Unicraft, Resin)

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TYPE: Interceptor. Project

ACCOMMODATION: Pilot only

POWER PLANT: One Kayaba Model 1 ramjet engine rated at 750 kp thrust at 457 mph and four solid fuel rocket boosters for take-off, rated at 7.200 kp thrust

PERFORMANCE: 559 mph (estimated)

COMMENT: The Kayaba “Katsuodori” (“Booby Gannet”) was the result of the endeavor to design a single-seat, ramjet-powered interceptor-minded platform which utilized a short, tailless fuselage configuration with swept-back wing main planes. The cockpit would be held well-forward and offered exceptional vision for the pilot. The mid-mounted main planes were affixed ahead of midship with each tip capped by small vertical stabilizers. The ramjet propulsion system was buried within the tubular fuselage and a rocket-assist scheme (consisting of four externally-held rocket pods) was to be used. The rocket pods were installed under the wing roots and jettisoned once their usefulness had run out. Having achieved the required speeds, the aircraft would then continue on under ramjet power with a flying window of about 30 minutes being estimated. To aspirate the ramjet, the nose section featured an air intake. No conventional undercarriage was provided. Instead the aircraft would glide back home powerless and land on a belly-mounted skid. The ramjet under consideration for the project became the Kayaba Model 1 which promised 750 kp thrust output.
Since the aircraft never achieved prototype form, performance specifications were estimated and this included a maximum speed of 560 miles per hour with a rate-of-climb around 11,000 feet-per-minute. The latter would prove a good quality to have in interception sorties. The service ceiling was listed at 49,215 feet
As an interceptor attempting to tackle very large, slow-moving (but well-defended) targets, it was seen to arm the fighter appropriately through 2 x 30mm Ho-301 series cannons – this was a suitable arrangement to counter even the high-flying and technologically advanced Boeing B-29 “Superfortress” which had made its presence known since mid-1944. The cannons would have been embedded in the sides of the nose.
Design work on the “Katsuodori” progressed into 1943 and plans were underway to begin construction of a working prototype for the following year. However, Japan’s fortunes in the war had worsened into 1944 and the attention of authorities turned to more viable military weapons such as the Rikugun (Mitsubishi) Ki-202 “Sharp Sword”, based on a rocket-powered interceptor developed by Mitsubishi as Ki-200 “Shusui” for the IJAAF and J8M-1 for the IJNAF on the basis of the German Messerschmitt Me 163 “Komet” (Ref.: 24).

Nightfighter

Aichi S1A1 “Denko” (“Bolt of Light”), A+V Models, Resin)

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TYPE: Night fighter

ACCOMMODATION: Crew of two

POWER PLANT: Two Nakajima NK9K-s radial engines, rated at 2,000 hp each

PERFORMANCE: 360 mph

COMMENT: The Aichi S1A “Denko” (“Bolt of Light”) was a Japanese night fighter, intended to replace the Nakajima J1N1-S “Gekko” (“Moonlight”, Allied code name “Irving”). It was to be, like the “Gekko”, equipped with radar to counter the B-29 air raids over the Japan. Development time increased while trying to overcome design shortcomings, such as the insufficient power of the Navy’s requested Nakajima “Homare” engines, resulting in no aircraft being completed before the war ended.
Because it was full of special equipment the “Denko’s” service weight exceeded ten thousand kilograms. Some of this specialized equipment included oxygen injection but the turbocharger’s remote location from the engine caused many problems. Because the initial prototypes’ engines did not pass Navy standards only two were ever manufactured. Two more had been planned before cancellation that would have used the more powerful Mitsubishi HI MK9A Ru or MK10A Ru engines.
Additionally, Tonokai earthquake occurred in December 1944 and the aircraft factories and prototypes were badly damaged. On 1945 June 9 the airstrikes on Aichi Kokuki KK and Aichi Tokei Denki Seizo Co, Ltd blew up the first prototype and forced movement of the second to the Gifu large Sadakazu factory to be assembled. But on July 9 of that year another airstrike destroyed the second prototype. At that time Aichi S1A “Denko” was the most massive fighter developed in Japan’s naval history (Ref.: 24).

Fighter, Fighterbomber

Kawanishi N1K2-J “Shiden Kai” (“Violet Lightning”,“George”) , (Hasegawa)

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TYPE: Interceptor fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Nakajima NK9H-S “Homare 23” radial engine, rated at 2,000 hp

PERFORMANCE: 369 mph at 18,375 ft

COMMENT: In 1943, while the Kawanishi N1K1-J “Shiden” was being evaluated by the Japanese Navy, preliminary design work on an advanced version of the aircraft had already begun at Kawanishi and the N1K1-J was placed in production only as a stop-gap measure pending availability of a new version designed N1K2-J. The prime reason for designing the N1K2-J was to eliminate the need for a long and complex undercarriage of the earlier version, and consideration was also given to simplifying construction and maintenance. To achieve this goal, the wings were moved to the lower fuselage, conventional main gear legs of reduced length were adopted and the fuselage and tail surfaces were entirely redesigned. The result was a virtually new aircraft retaining only the wings and armament of the N1K1-J.
The prototype of the N1K2-J “Shiden-Kai” (“Violet Lightning-Modified”) was flown for the first time on December, 1943, and successfully completed its manufacture’s trials within fifteen weeks before handed over to the Navy in April 1944. Despite persistent difficulties with the unreliable “Homare 21” engine, the N1K2-J had all the qualities of a successful fighter aircraft and production aircraft began rolling off the assembly lines. Unfortunately for the Japanese, the production fell considerably behind schedule as bombing by Boeing B-29 “Superfortresses” led to shortage of engines and equipment. The companies involved in the “Shiden-Kai” production program delivered only a token number of aircraft.
In operation the N1K2-J revealed itself as a truly outstanding fighter capable of meeting on equal terms of best Allied fighter aircraft. Against the high-flying B-29s the “Shiden-kai” was less successful as its climbing speed was insufficient and the power of the “Homare 21” fell rapidly at high altitudes.
In total 423 N1K2-J “Shiden-Kai” were produced including eight prototypes (Ref.: 1).

Fighter

Kawanishi N1K1-J „Shiden“ (Violet Lightning“, “George“) 341.Kokutai, 402. Hikotai (MPM)

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TYPE: Land-based interceptor fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Nakajima NK9H “Homare” radial engine, rated at 1,990 hp

PERFORMANCE: 363 mph at 19,355 ft

COMMENT: The Kawanishi N1K1-J “Shiden” (“Violet Lightning”) was an Imperial Japanese Navy Air Service land-based version of the N1K. Assigned the Allied codename “George”, the N1K-J was considered by both its pilots and opponents to be one of the finest land-based fighters flown by the Japanese during World War II.
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 more need for a fighter to fulfil 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 combat flaps that adjusted their angle in response to acceleration; thus freeing up the pilot’s concentration and reducing the chance of stalling in combat. The N1K1-J did have temperamental flight characteristics, however, 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 that, due to poor heat treatment of the wheels, their failure on landing would result in the landing gear being torn off. 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. The N1K1-J aircraft were used very effectively over Formosa (Taiwan), the Philippines, and, later, Okinawa. Before production was switched to the improved Kawanishi N1K2-J “Shiden-Kai”, 1,007 aircraft were produced, including prototypes (Ref.: 24).