Category Archives: Imperial Navy Air Force

Japan

Fighter

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

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TYPE: High-altitude fighter

ACCOMMODATION: Pilot only

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).

Heavy Bomber, Torpedobomber, Reconnaissance, Cargo

Kawanishi H6K4 “Type 97 Large Flying Boat” („Mavis“), 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 nine

POWER PLANT: Four Mitsubishi “Kinsei 46” radial engines, rated at 930 hp each

PERFORMANCE: 211 mph at 19,685 ft

COMMENT: The Kawanishi H6K4 was an Imperial Japanese Navy flying boat used during WW II for maritime patrol duties. The IJ Navy designation was “Type 97 Large Flying Boat”, The Allied reporting name for the type was “Mavis”.
The aircraft was designed in response to a Navy requirement of 1934 for a long range flying boat and incorporated knowledge gleaned by a Kawanishi team that visited the Short Brothers factory in the UK, at that time one of the world’s leading producers of flying boats, and from building the Kawanishi H3K, a license-built, enlarged version of the Short “Rangoon”. The Type S, as Kawanishi called it, was a large, four-engine monoplane with twin tails, and a hull suspended beneath the parasol wing by a network of struts. Three prototypes were constructed, each one making gradual refinements to the machine’s handling both in the water and in the air, and finally fitting more powerful engines. The first of these flew on 14 July 1936 and was originally designated “Navy Type 97 Flying Boat”, later H6K. Eventually, 217 would be built.
H6Ks were deployed from 1938 onwards, first seeing service in the Sino-Japanese War and were in widespread use by the time the full-scale Pacific War erupted, in 1942. At that time of the war, four Kokutai (Air Groups) operated a total of 66 H6K4s.
The type had some success over South East Asia and the South Pacific. H6Ks had excellent endurance, being able to undertake 24-hour patrols, and were often used for long-range reconnaissance and bombing missions. From bases in the Dutch East Indies, they were able to undertake missions over a large portion of Australia. However, the H6K became vulnerable to a newer generation of heavier armed and faster fighters. It continued in service throughout the war, in areas where the risk of interception was low. In front-line service, it was replaced by the Kawanishi H8K “Type 2 Large-sized Flying Boat“, Allied code name “Emily” (Ref.: 24).

Glider, Trainer

Yokosuka MXY8 “Akigusa” (“Autumn Grass”), (Wings Models, Vacu-formed)

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TYPE: Tailless glider/trainer

ACCOMMODATION: Pilot only

POWER PLANT: None

PERFORMANCE: No data available

COMMENT: The Yokosuka MXY8 “Akigusa” (“Autumn grass”) was a training glider built in parallel with the Mitsubishi J8M rocket-powered interceptor aircraft.
The J8M was to have simply been a licence-built Messerschmitt Me 163 “Komet” (“Comet”), but due to difficulties in obtaining technical materials from Germany, it eventually had to be designed almost from scratch. The MXY8 was designed in parallel with the J8M to validate the design, and then to provide pilot training during the development of the actual interceptor. The Imperial Japanese Army Airforce designation for the trainer was Mitsubishi Ku-13
The MXY8 was built entirely of wood, and fitted with ballast tanks that would be filled with water to simulate the weight and therefore flight characteristics of a fully equipped J8M. Some 50-60 of these gliders were eventually built.
A more advanced trainer, the MXY9, equipped with a primitive turbojet engine was planned, but was never produced (Ref.: 24).

Fighter

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

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TYPE: Interceptor fighter

ACCOMMODATION: Pilot only

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).

Reconnaissance

Mitsubishi F1M2 (“Pete”), IJN BS “Yamato” (Airmodel, Resin)

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TYPE: Observation float seaplane

ACCOMMODATION: Pilot and observer

POWER PLANT: One Mitsubishi “Zuisei” air-cooled radial engine, rated at 875 hp

PERFORMANCE: 230 mph at 11,285 ft

COMMENT: The Mitsubishi F1M (Allied code name “Pete”) was a Japanese reconnaissance floatplane of WW II. The F1M was originally built as a catapult-launched reconnaissance float plane, specializing in gunnery spotting. The “Pete” took on a number of local roles including convoy escort, bomber, anti-submarine, maritime patrol, rescue, transport, and anti-shipping strike. The type was also used as an area-defense fighter and fought dogfights in the Aleutians, the Solomons and several other theaters. In the New Guinea front, it was often used in aerial combat with the Allied bombers and Allied fighters. It was the last biplane type of the Imperial Japanese Navy (IJN), with 1,118 built between 1936 and 1944. It provided the IJN with a very versatile operations platform and was allocated to nearly all Japanese battleships, cruisers, aircraft tenders, but also to several shore bases.

The aircraft shown here was operated from IJN battleship “Yamato” in August 1944. The “Yamato” was the lead ship of the “Yamato” class of Imperial Japanese Navy World War II battleships. She and her sister ship, “Musashi”, were the heaviest battleships ever constructed, displacing 72,800 tonnes at full load and armed with nine 46 cm 45 Caliber Type 94 main guns, which were the largest guns ever mounted on a warship. Neither ship survived World War II (Ref.: 24).

Fighter, Projects

Kyushu J7W2 (Hasegawa)

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TYPE: Interceptor fighter. Project

ACCOMMODATION: Pilot only

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).

Fighter

Kyushu J7W1 “Shinden” (“Magnificent Lightning”), (Tamiya)

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TYPE: Interceptor fighter

ACCOMMODATION: Pilot only

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).

Fighterbomber, Reconnaissance

Kawanishi E15K1 “Shiun” (“Violet Cloud”, “Norm”)(Aoshima, Parts Scratch-built)

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TYPE: High-speed reconnaissance float plane

ACCOMMODATION: Crew of two

POWER PLANT: One Mitsubishi MK4S Kasei 24 radial engine, rated at 1,850 hp

PERFORMANCE: 291 mph at 18,700 ft

COMMENT: In 1939 the Imperial Japanese Navy instructed the Kawanishi Aircraft Company to develop a two-seat high-speed reconnaissance floatplane, which was required to have sufficient performance to escape interception by land based fighters. It was planned to equip a new class of cruisers, intended to act as a flagship for groups of submarines operating six of the new floatplanes to find targets. Kawanishi designed a single-engine low-wing monoplane, powered by a 1,460 hp Mitsubishi MK4D Kasei 14 radial engine driving two contra-rotating two-blades propellers, the first installation of contra-rotating propellers produced in Japan, while a laminar flow airfoil section was chosen to reduce drag. It had a single main float under the fuselage and two stabilising floats under the wing. The stabilising floats were designed to retract into the wing, while the central float was designed to be jettisoned in case of emergency, giving a sufficient increase in speed to escape enemy fighters. It is noteworthy to mention that similar design was chosen by Kawabishi’s engineers for the new Kawanishi N1K1 “Kyofu” float seaplane fighter.
The first prototype of Kawanishi’s design, designated E15K1 in the Navy’s short designation system made its maiden flight on 5 December 1941. Five more prototypes followed during 1941-42. Problems were encountered with the retractable stabilising floats, resulting in several accidents when the floats could not be lowered for landing, and the system was eventually abandoned, with the stabilising floats being fixed, and a more powerful Mitsubishi MK4S Kasei 24 engine fitted to compensate for the increased drag.
Despite these problems, the E15K1 was ordered into limited production as the Navy Type 2 High-speed Reconnaissance Seaplane “Shiun” Model 11. Six were sent to Palau in the South Pacific, but these were quickly shot down by Allied fighters, as the jettisonable float failed to separate on demand (although subjected to wind tunnel testing, the float separation system had never been tested on the actual aircraft). This resulted in the cancellation of production in February 1944, with only 15 “Shiuns” completed, including the six prototypes (Ref.: 24).

Reconnaissance

Yokosuka R2Y1 “Keiun” (“Beautiful Cloud”), (Wings Models, Vacu-formed)

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TYPE: Long-range reconnaissance aircraft

ACCOMMODATION: Pilot and radio operator/navigator

POWER PLANT: One Aichi Ha-70 (twin-coupled Aichi “Atsuta 30s”) twenty-four cylinder liquid-cooled engine, rated at 3,400 hp

PERFORMANCE: 447 mph at 32,810 ft

COMMENT: In 1942 the Japanese Navy initiated the development of a new class of aircraft to fulfil the role as long-range high-speed land-based reconnaissance aircraft. The first projected aircraft was planned around the new 2,500 hp twenty-four cylinder, liquid-cooled engine then under development by Mitsubishi. But in 1943, inspired by evaluation of the Heinkel He 119 V4 acquired from Germany that was powered by two coupled engines buried in the fuselage behind the cockpit the design was changed again. Now the Aichi Ha-70 twin-coupled “Atsuta “30 was installed in the fuselage driving a single six-bladed tractor propeller via an extension shaft. Completed in April 1945 the prototype made its first flight on 8 May 1945. Unfortunately, this flight had to be cut short because of an abnormal rise in oil temperature, while a few days later an engine fire on the ground necessitated a complete engine change. Before this could be done, the R2Y1 was destroyed by American bombs. At the end of the war a second R2Y1 prototype was under construction and the design of a turbojet engine-powered fast attack bomber R2Y2 had almost been completed (Ref. 1).

Fighter

Nakajima J8N “Kitsuka” (“Kikka”) (“Orange Blossom”) (Pegasus Models)

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TYPE: Interceptor, fighter

ACCOMMODATION: Pilot only

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 J8N “Kitsuka” (“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 later 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).