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 HA-40, 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.
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).
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).
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).
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).
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).
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).
POWER PLANT: One Ishikawajima Ne-130 turbojet engine, rated at 900 kp thrust
PERFORMANCE: No data available
COMMENT: The concept of Kyushu J7W1 unique canard configuration was due to designers of the Technical staff of the Japanese Navy. From the onset of that project it was envisaged to replace the rear-mounted Mitsubishi Ha-43 air-cooled radial engine, which drove a six-blade pusher propeller, with the new turbojet engines under development at that time.
Following some initial work on that concept, the staff of Dai-Ichi Kaigun Koku Gijitsusho (First Naval Air Technical Arsenal) designed a glider to test the aircraft’s handling qualities at low speeds. Three prototypes of the MXY6 were built for the Navy by Chigasaki Seizo K.K. and these all-wood gliders with moderately swept wings supporting tall tail surfaces inboard the ailerons began flight trials in autumn of 1943.
Although the “Shinden” was expected to be a highly maneuverable interceptor, only two prototypes were finished before the end of war. And of course the turbojet engine powered Kyushu J7W2 was never realized, it didn’t even reach the drawing board (Ref.: 24).
POWER PLANT: One Mitsubishi Ha-43 12 (MK9D) radial engine, rated at 2,130 hp
PERFORMANCE: 469 mph
COMMENT: The Kyūshū J7W1 “Shinden”( “Magnificent Lightning”) fighter was a Japanese propeller-driven aircraft prototype with wings at the rear of the fuselage, a nose mounted canard, and pusher engine. Developed by the Imperial Japanese Navy (IJN) as a short-range, land-based interceptor, the J7W was a response to Boeing B-29 “Superfortress” raids on the Japanese home islands. In the IJN designation system, “J” referred to land-based fighters and “W” to Watanabe Tekkōjo, the company that oversaw the initial design..
The construction of the first two prototypes started in earnest by June 1944, and the first prototype was completed in April 1945. The 2,130 hp Mitsubishi MK9D (Ha-43) radial engine and its supercharger were installed behind the cockpit and drove a six-bladed propeller via an extension shaft. Engine cooling was to be provided by long, narrow, obliquely mounted intakes on the side of the fuselage. It was this configuration that caused cooling problems while running the engine while it was still on the ground. This, together with the unavailability of some equipment parts postponed the first flight of the “Shinden”. Even before the first prototype took to the air, the Navy ordered the J7W1 into production, with a quota of 30 “Shinden” a month given to Kyushu’s Zasshonokuma factory and 120 from Nakajima’s Handa plant. It was estimated some 1,086 “Shinden” could be produced between April 1946 and March 1947.
On August 1945, the prototype first flew from Itazuke Air Base. Two more short flights were made, a total of 45 minutes airborne, one each on the same days as the atomic bombings of Hiroshima and Nagasaki occurred, before the war’s end. Flights were successful, but showed a marked torque pull to starboard (due to the powerful engine), some flutter of the propeller blades, and vibration in the extended drive shaft.
A turbojet engine–powered version, the Kyushu J7K2, was considered, but never even reached the drawing board (Ref.: 24).
POWER PLANT: Two Ishikawajima Ne-20 turbojet engines, rated at 475 kp each
PERFORMANCE: 433 mph at 32,800 ft (estimated)
COMMENT: Design work on the Nakajima “Kikka” – the only Japanese turbojet powered aircraft capable of taking-off on its own power, albeit only twice during World War II – began in September 1944. The enthusiastic reports on the progress of the Messerschmitt Me 262 twin-jet fighter received from the Japanese Air Attaché in Germany had prompted the Naval Staff to instruct Nakajima to design a single-seat twin-jet attack fighter based on the German Me 262.
The aircraft externally resembled the Me 262 but was smaller. Two turbojets were mounted in separate nacelles under the wing to allow the installation of engines of various types. Provisions were made for folding wings, to enable the aircraft to be hidden in caves and tunnels and also for ease of production by semi-skilled labor. Initial plans to power the aircraft by two N-12 turbojet engines each delivering 340 kp thrust were refused due to insufficient thrust. Fortunately, photographs of the German BMW 003 axial-flow turbojet had been obtained and from these the Japanese were able to design a similar turbojet, designate Ne-20, offering a thrust of 475 kp. Completed in August 1945, the first “Kikka” made its maiden flight. Four days late the pilot aborted a take-off during the second flight, the accident being caused by mounting the two rocket-assisted-take-off (RATO) rockets at an incorrect angle. A second prototype (shown here) was almost ready for flight trials and eighteen additional prototypes and pre-production aircraft were ready in various stages of assembly when with the end of WW II the development of the aircraft was terminated (Ref.: 1).
Scale 1:72 aircraft models of World War II
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