Category Archives: Fighter


Kugisho High-Speed Aircraft Project with DB 601A (Unicraft Models, Resin)

TYPE: High speed fighter project


POWER PLANT: One Daimler-Benz DB 601A liquid-cooled engine, rated at 1,159 hp

PERFORMANCE: No data available

COMMENT: Every aircraft creator seeks to reduce drag in their designs. The more drag, the slower the aircraft moves through the air due to the resistance. Drag cannot be completely removed from a design, but even in the early years of aviation various methods for minimizing drag were investigated and many different solutions were tried.
Not surprisingly, such applications were valued by those providing the military with aircraft and in Japan, prior to the outbreak of hostilities with the US, the Dai-lchi Kaigun Kok[ Gijutsu-sho (Yokosuka Naval Air Technical Arsenal, Kugisho) would study such efforts in an attempt to produce fast flying aircraft.
With the war clouds looming on the horizon, the seeds planted by the air racers of the 1920s and early 1930s were germinating in the aircraft used by the air forces of the major powers. Designs by Curtiss for the US Army Air Force were influenced by the Curtiss racers while the retractable landing gear of the 1920 Dayton Wright RB racer would become a hallmark of Grumman aircraft such as the F2F. In Great Britain, R. J. Mitchell would draw heavily from his experience designing Schneider Trophy racers to build the Supermarine Type 300 which would eventually evolve into the Supermarine Spitfire.
On 26 April 1939 German test pilot Fritz Wendel flew to a new world speed record of almost 469 mph with a Messerschmitt Me 209. The Me 209 was solely designed to break speed records and was a completely separate aircraft from the Messerschmitt Bf 109 that entered service with the German Luftwaffe at that time. It shared only its Daimler-Benz DB 601 liquid-cooled engine with the Bf 109.
Consequentially, Japan sought to produce racing aircraft and planes designed to beat world speed records. In 1938, a group of designers sought to produce a high-speed aircraft to challenge the world air speed record. Once war had broken out this aircraft, called the Ken lll, was soon taken over by the Imperial Japanese Army (IJA). Redesignated the Ki-78, its development was continued under Kawasaki. During this time, it may have been the Imperial Japanese Navy (IJN) who decided to conduct its own studies of high speed aircraft with Kugisho assigned the task of doing so. Whether the studies were initiated in response to the IJA’s own high-speed aircraft project is unknown but the prevalent aircraft design philosophy of both the IJN and the IJA prior to the war was of speed, agility and range at the expense of fire- power, durability and protection.
Kugisho examined over half a dozen aspects of aerodynamics in order to produce data on what would be needed to realize an aircraft capable of significant speed. One leading point of research was the main wings. The shape of a wing is one of the more critical aspects of aircraft design. Factors such as wing loading, expected air speeds, angles of attack and the intended use of the aircraft all influence how the wing is shaped. For high speeds, a low aspect ratio wing is often considered. Typically, these are short span wings with the benefits of higher maneuverability and less drag. In addition, having a backward sweep to the wing also lowers drag. The drag most associated with wings is termed induced drag, which is caused by wing tip vortices that change how the air flows over the wings. This change results in less and less lift which then requires a higher and higher angle of attack to compensate and, from this, induced drag results. Elliptical wings offer less induced drag than more conventional straight wings. However, low aspect ratio wings are more prone to larger vortices because they cannot be spread out across a longer wing.
Kugisho’s study on wing shapes was the likely result of testing various airfoils in a wind tunnel to determine their effectiveness and record the results. Another aspect Kugisho engineers reviewed were the merits and flaws of using either an inline or a radial engine and how each type reduced the form drag. In both cases the engineers drew up two concept aircraft and each made use of streamlining. Streamlining is the process of shaping an object, in this case, a fuselage, to increase its speed by reducing the sources of drag.
One concept used the German 1,159hp Daimler-Benz DB 601A, a 12-cylinder, inverted-V, liquid-cooled, inline engine. This engine would be license built for the IJN as the Aichi AEl Atsuta (the ‘A’ stood for Aichi, ‘E’ for liquid-cooled and ‘l’ for first liquid-cooled engine.  Atsuta was a holy shrine in Aichi Prefecture) and for the IJA as the Ha-40, before it was renamed the [Ha-60] 22.
The second concept aircraft (Kugisho High-Speed Aircraft Project with NK-1B) used a 1,000hp Nakajima NKlB Sakae 11 which was a 14-cylinder, air-cooled, radial engine. This engine was a license version of the French Gnome-Rhone l4K Mistral Major (in engine nomenclature, the ‘N’ was for Nakajima, ‘K’ for air-cooled, ‘1’as the first air-cooled engine, while the ‘B’ was for the second version of the NKl; Sakae means prosperity in Japanese).
Kugisho would use the same basic airframe for the engine study. It consisted of a well streamlined fuselage with the pilot mounted in a cockpit set behind the wing and just forward of the vertical stabilizer. This style was found in a number of racing aircraft such as the American GeeBee Rl and Geebee Z. Both aircraft used a standard tail-sitter configuration for the landing gear. The concept equipped with the DB 601A engine had a fuselage shape that was not unlike the Kawasaki Ki-61 Hien (“Swallow”, codenamed “Tony” by the Allies) which would appear in prototype form in December 1941 . The wings were mounted low on the fuselage. The fuselage appearance was due to the inverted-V engine which, by design, offered lower height, weight and length when compared to more conventional engines.
By contrast, the concept using the Nakajima NKlB had a more ovoid fuselage shape, the result of the height of the radial engine. To maintain the aerodynamic streamlining a large spinner was used. Also, in contrast to the DB 601A equipped design, the wings were mounted mid-fuselage.
Kugisho would not produce any direct prototype aircraft from either concept. lnstead, results of the various studies were likely kept available as reference for engineers to access as a means of obtaining data on the aerodynamic problem. Perhaps Kugisho in hindsight considered themselves fortunate to not have expended additional expense and effort in producing working prototypes given the failure of the IJA’s Kawasaki Ki-78, a program that lingered on into 1944 and never met its design goals (Ref.: Dyer III, Edwin M.: Japanese Secret Projects, Experimental Aircraft of the IJA and IJN 1939-1945, Midland Publishing, Hersham, U.K., 2010).

Mitsubishi A7M2 “Reppū” (“Strong Gale”, “Sam”), (MPM Models)

TYPE: Carrier-borne and land-based fighter


POWER PLANT: One Mitsubishi Ha-43 radial engine, rated at 2,200 hp

PERFORMANCE: 390 mph at 21,660 ft

COMMENT: Towards the end of 1940, the Imperial Japanese Navy asked Mitsubishi to start design on a 16-Shi carrier-based fighter, which would be the successor to the carrier-based Mitsubishi A6M “Rei-sen” (“Zeke”, Allied reporting code “Zero”). At that time, however, there were no viable high-output, compact engines to use for a new fighter. In addition, Mitsubishi’s design’s team was preoccupied with addressing early production issues with the A6M2b as well as starting development on the A6M3 and the 14-Shi interceptor which would later become the Mitsubishi J2M “Raiden” (Allied code “Jack”), a land-based interceptor built to counter high-altitude bombers). As a result, work on the “Rei-sen” successor was halted in January 1941.
In April 1942, the development of the A6M3 and the 14-Shi interceptor was complete, and the Japanese Navy once again tasked Mitsubishi with designing a new “Zero” successor to become the “Navy Experimental 17-Shi Ko (A) Type Carrier Fighter “Reppu” (“Strong Gale”, Allied reporting code “Sam”). In July 1942 the Navy issued specifications for the fighter: it had to fly faster than 397 mph above 20,000 ft, climb to 20,000 ft in less than 6 minutes, be armed with two 20 mm cannon and two 0.51 in machine guns, and retain the maneuverability of the A6M3 “Rei-sen”.
As before, one of the main hurdles was engine selection. To meet the specifications the engine would need to produce at least 2,000 hp, which narrowed choices down to Nakajima’s NK9 (Ha-45) under development (later becoming “Homare”), or Mitsubishi’s MK9 (Ha-43), which was also still being developed. Both engines were based on 14-cylinder Nakajima “Sakae” and Mitsubishi “Kinsei”, respectively) engines converted to 18-cylinder power plants. The early NK9 had less output but was already approved by the Navy for use on the Yokosuka P1Y “Ginga” (Allied code “Frances”), while the larger MK9 promised more horsepower.
With the larger, more powerful engine, wing loading became an issue. With the MK9 the engineers concluded it could fulfill the requirements; however, production of the MK9 was delayed compared to the NK9, and the Japanese Navy instructed Mitsubishi to use the NK9.
Work on the 17-Shi was further delayed by factories prioritizing Mitsubishi  A6M “Reisen” and Mitsubishi G4M (Allied code “Betty”) bomber production as well as further work on A6M variants and addressing Mitsubishi J2M “Raiden” issues. As a result, the 17-Shi, which became the A7M1, officially flew for the first time on 6 May 1944, four years after development started. The aircraft demonstrated excellent handling and maneuverability, but was underpowered as Mitsubishi engineers feared, and with a top speed similar to the A6M5 “Rei-sen”/”Zeke”. It was a disappointment, and the Navy ordered development to stop on 30 July 1944, but Mitsubishi obtained permission for development to continue using the Ha-43 engine, flying with the completed Ha-43 on 13 October 1944. The Mitsubishi A7M2 “Reppu” now achieved a top speed of 390 mph, while climb and other areas of performance surpassed the “Zero”, leading the Navy to change its mind and adopt the aircraft. The A7M2 “Reppu” was also equipped with automatic combat flaps, used earlier on the Kawanishi N1K-J “Shiden” (Allied code “George”), significantly improving maneuverability.
In June 1945, ace pilot Saburo Sakai was ordered to Nagoya to test the airplane. He declared it to be the fastest fighter he had ever seen, able to surpass anything on the air, Japanese or American. He claimed it could fly in circles, while ascending, around a Grumman F6F “Hellcat” or a North American P-51 “Mustang”, and that engineers stated it could fight at up to 39,370 ft.
When the war in the Pacific area ended a total of 10 Mitsubishi A7M “Reppu’s” were built including only one production aircraft A7M2 (Ref.: 24).

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

TYPE: Carrier-borne fighter, fighter-bomber


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).

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

TYPE: Interceptor, fighter. Project


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.

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

TYPE: Interceptor. Project


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).

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

TYPE: Interceptor fighter


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).

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

TYPE: Land-based interceptor fighter


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).

Nakajima A6M2-N “Rufe”, Sasebo Naval Flying Group

TYPE: Float seaplane fighter


POWER PLANT: One Nakajima NK1C “Sakae” 12 radial engine, rated at 950 hp

PERFORMANCE: 270 mph at 16,400 ft

COMMENT: The Nakajima A6M2-N (Navy Type 2 Interceptor/Fighter-Bomber) was a single-crew floatplane based on the Mitsubishi A6M “Zero” Model 11. The Allied reporting name for the aircraft was “Rufe”.
The A6M2-N floatplane was developed from the Mitsubishi A6M “Zero” Type 0, mainly to support amphibious operations and defend remote bases. It was based on the A6M-2 Model 11 fuselage, with a modified tail and added floats.
The aircraft was deployed in 1942, referred to as the “Suisen 2” (“Hydro fighter type 2”), and was only utilized in defensive actions in the Aleutians and Salomon Islands operations. Such seaplanes were effective in harassing American PT boats at night. They could also drop flares to illuminate the PTs which were vulnerable to destroyer gunfire, and depended on cover of darkness.
The seaplane also served as an interceptor for protecting fueling depots they also served as fighters aboard seaplane carriers “Kamikawa Maru” in the Salomons and Kuriles areas and aboard Japanese raiders “Hokaku Maru” and “Aikoku Mari” in Indian Ocean raids. In the Aleutian Campaign this fighter engaged with RCAF Curtiss P-40 “Warhawk”, Lockheed P-38 “Lightning” fighters and Boeing B-17 “Flying Fortress” bombers. The aircraft was used for interceptor, fighter-bomber, and short reconnaissance support for amphibious landing, among other uses.
Later in the conflict the Otsu Air Group utilized the A6M2gs-N as an interceptor alongside Kawanishi N1K1 “Kyofu”(“Rex”) aircraft based in Biwa lake in the Honshū area.
The large float and wing pontoons of the A6M2-N degraded its performance by only about 20%. However, this caused the A6M2-N to be unable to confront the first generation of Allied fighters. A total of 327 were built, including the original prototype (Ref. 24).

Nakajima J5N1 “Tenrai” (“Heavenly Thunder”),Prototype, (A+V Models, Resin)

TYPE: High-altitude fighter


POWER PLANT: Two Nakajima “Homare 21” radial engines, rated at 1,990 hp each

PERFORMANCE: 371 mph at 19,685 ft

COMMENT: The Nakajima J5N was a Japanese fighter aircraft of WW II. The J5N was developed as twin-engine interceptor for countering attacks by Boeing B-29 “Superfortress” bombers.
During the spring of 1943, the Imperial Japanese Navy Air Force (IJNAF) issued an 18-Shi specification for a single-seat twin-engine interceptor capable of reaching a top speed of 414 mph at 19,690 ft. Nakajima submitted a proposal based on the earlier Nakajima N1N1 “Gekko” three-seat night fighter, although this new aircraft – designated Nakajima J5N1 – was slightly smaller. The layout of the J5N was similar to the J1N: a low set wing on which were mounted the two power plants, 1,990 hp Nakajima “Homare 21” air-cooled radial engines, with a long fuselage ending in a conventional tail arrangement. For maximum utilization of the power from the twin engines, large four-blade propellers were fitted which also featured large spinners (as fitted to the J1N). The main wheels retracted rearwards into the engine nacelles, and the tailwheel was fixed. The cockpit was set above the wing, and featured a starboard-opening canopy. The nose was streamlined to offer the pilot an excellent forward view during landing, takeoff and taxiing.
Impressed with the design, the JNAF authorized the development of the J5N1, assigned the name “Tenrai” (“Heavenly Thunder”), and six prototypes were requested to be built. Progress was impeded by the failure of the engines to produce their promised power, and by a steady increase in the weight of the airframe as the need to reverse the long-standing policy of giving low priority to armor protection led to a buildup of weight and a drop in performance. The first prototype – shown here  – lacking its armament – made its first flight July 13, 1944, and was something of a disappointment. The top speed attained was only 371 mph – far below the specified 414 mph of the requirement. Despite the other five prototypes also having flown with numerous enhancements, the aircraft never achieved its design speed, and the project was abandoned soon after in February 1945. Four of the six experimental aircraft were lost to accidents (Ref.: 24).

Kawanishi J6K1 “Jinpu” (“Squall”), RS Models, Resin

TYPE: Interceptor fighter


POWER PLANT: One Nakajima NK9H “Homare” 42 radial engine, rated at 2,000 hp

PERFORMANCE: 426 mph at 32,810 ft

COMMENT: The Kawanishi J6K1 Jinpu was a purpose-built land based interceptor designed for the Imperial Japanese Navy Air Force, but that didn’t enter production because of the success of the same company’s Kawanishi N1K1-J “Shiden” (“Violet lightning”, Allied code “George”).
The J6K1 was developed from the Kawanishi J3K1 of 1942. This was to have been powered by the Mitsubishi MK9A radial engine, and would have been a fairly standard looking radial engined fighter, but it didn’t progress beyond the early design stage.
Work on the J6K1 began in 1943. This time the aircraft was to use the Nakajima “Homare” 42 engine, the design progressed far enough to receive a popular name, the Jinpu (Squall). The new interceptor would have been very heavily armed, with two 30mm cannon and two 13.2mm machine guns, and with a good top speed of 426mph. The J6K1 never entered production. Kawanishi had also produced the N1K1 Kyofu” (“Mighty wind, Allied code “Rex”) float plane fighter, which was followed by a normal landed based version, the Kawanishi N1K1 “Shiden”. This was then superseded by the N1K2-J “Shiden-Kai, a smaller aircraft than the J6K, armed with four 20mm cannon and with sufficiently impressive performance to meet the Navy’s requirements. The N1K2-J was produced in large numbers, while the J6K1 was cancelled (Ref.: 24).