Category Archives: Projects

Projects

Kokukyoko “Syusuishiki Kayaku ”, (“Autumn Water”), Unicraft Models, Resin

TYPE: Rammer aircraft

ACCOMMODATION: Pilot only

POWER PLANT: Four Type 4 Mk. 1 Model 20 solid fuel rockets with a combined 1,102 kp thrust

PERFORMANCE: 699 mph (estimated)

COMMENT: The practice of ramming, in Japanese “tai-atari”, which literally means “body crashing”, was not unique to Japan. During WW II the deliberate ramming of one aircraft by another aircraft was performed by the Russians, Germans as well as Japanese and all made ramming a part of their war doctrine.
The Japanese would use aircraft already in operational service for ramming attacks such as that Kawasaki Ki-45 and even stripped down Kawasaki Ki-61 “Hein” fighters. It was long thought that Japan never developed a dedicated rammer aircraft of its own but this is no longer the case. Recently discovered in the archives of the Japanese National Institute for Defense Studies is just such a project.
The aircraft was a joint venture between the Imperial Japanese Army (IJA) and the Imperial Japanese Navy (IJN), something that occurred with more regularity towards the closing stage of WW II. The design was based on the “Syusuishiki Kayaku” Rocketto (“Autumn Water”-type ram attack rocket), a project started in March 1945 for an unmanned, remote controlled anti-bomber missile. The plan was to ground launch the missile, guide it remotely towards the target, engage the target via ramming, and then recover the missile (if it survived the collision) for reuse.
Design work was carried out by the Kokukyoko (the Aeronautical Bureau) and, although a mockup was completed, the war ended before finalized production plans could be completed, let alone the missile ever being tested.
The piloted version used much the same design as the missile and was a small, tailless aircraft featuring low mounted 45′ swept wings. The fuselage was bullet shaped with a large vertical stabilizer into which the cockpit was blended. Located in the back of the fuselage were four Type 4 Mark 1 Model 20 rockets, the same as those used on the Kugisho MXYT “Oka” which on such a small aircraft pushed the maximum speed to an estimated 699 mph or just over Mach 0.91. lt is unknown if the design had swept wings because the designers  understood the principles in relation to overcoming compressibility problem at transonic speeds, or if the shape was chosen as a means to provide an angled cutting surface to facilitate ramming attacks, or as a drag reducing planform. The wings were strengthened to withstand the high impact forces experienced when striking the enemy bomber. Even though the rammer could rely on speed as a defense when under power, it still had to contend with the defensive armament of the B-29 and thought the pilot had some measure of armor plating and bulletproof glass to protect him. The aircraft was certainly capable of gliding back to base to be refueled and relaunched once it had conducted its attacks. Given the small size of the plane, no landing gear was fitted. As such, it is likely the underside of the fuselage was reinforced or had a skid installed. How it was to be launched is unknown – it could have been towed aloft, catapult launched or perhaps even vertically launched.
In a ram attack, typically the tail would be targeted because the loss of the tail assembly would send the bomber out of control. Striking the wings and engines was another focus of ramming attacks. Finally, the aircraft fuselage was the other key area to strike. The probable mission profile of the rammer flying from a ground base would include being positioned within very close proximity of likely bombing targets. With the short burn time of the rockets (8-10 seconds) the aircraft’s operational radius would have been very limited. After launching, as bombers came into range the pilot would attempt to ram into either the tail or wing of the target with the objective of severing it from the fuselage. If enough speed momentum remained after the initial hit, another ram attack would be made. Should the aircraft remain in flying condition and if the pilot did not elect to ram his entire plane into a target, he would return to base where the rockets would be replaced. If the bombers were still close by, he could fly another sortie. If the rammer was towed into the air, the rockets would most likely have been fired on approach and again after hitting a target. This would provide enough power to grant a second pass with sufficient speed to allow for significant damage to be inflicted on the bomber when it struck.
However, the Kokukyoko “Syusuishiki Kayaku” would remain a paper project only. It is unclear if the design was to be the definitive rammer model or simply a proposed concept (Ref.: Dyer III, Edwin M.: Japanese Secret Projects, Experimental Aircraft of the IJA and IJN 1939-1945, Midland Publishing, Hersham, U.K., 2010).

Tachikawa Ki-94-I (A+V Models, Resin)

TYPE: High-altitude fighter. Project

ACCOMMODATION: Pilot in pressurized cockpit

POWER PLANT: One Mitsubishi Ha-211 Ru radial engine, rated at 2,200 hp

PERFORMANCE: 485 mph at 32,810 ft (estimated)

COMMENT: Preliminary discussions regarding a heavily armed high-altitude fighter were held between the Koku Hombu and Tachikawa Hikoki K. K. in mid-1942. The new aircraft was to be fitted with a pressure cabin and capable of reaching a top speed of 490 mph.  The aircraft proposed by Tachikawa, which received the Kita designation Ki-94, was of a highly unconventional design. The aircraft was a large twin-boom monoplane, powered by two 2,200 hp Mitsubishi Ha-211 Ru air-cooled radials which were mounted fore and aft of the pilot’s cockpit and drove four-blade tractor and pusher propellers. The very heavy armament that should have been mounted on the aircraft should have been powerful enough to make short work of most US heavy bombers of that area at that time. A full-scale wooden mock-up of the Ki-94 was ordered and built although at the same time a contract was placed with Nakajima for another high-altitude fighter, the Ki- 87, with less stringent range requirements as a fall-back design for the Tachikawa Ki-94.
Notwithstanding the outstanding prospective performance, which however was judged by the technical department of the Japanese Army Air Force as “unduly optimistic” and too complex, the design was discarded. But in mid-1943 Tachikawa submitted a new proposal to meet the same requirements as the competitive Nakajima Ki-87. In order to avoid confusion the Kitai designation the first Tachikawa design received the designation Ki-94-I, and the new design Ki-94-II (Ref.: 1, 24).

Kogiken Plan I Type A Heavy fighter (Unicraft, Resin)

TYPE: Interceptor, fighter. Project

ACCOMMODATION: Pilot only

POWER PLANT: One Kawasaki Ha 40 liquid-cooled engine, rated at 1,100 hp

PERFORMANCE: No data available

COMMENT: In the summer of 1941, Rikugun Kokugijutsu Kenkyujo (Japanese Army Aerotechnical Research Institute, short named “Kogiken”) formed a design group under the leadership of Ando Sheigo. The task was to study Japanese aviation technology in terms of what was possible at present and in the near future. Additionally, some effort was to be spent on reviewing the aircraft technology of other countries. From the results the group was to assemble and draft proposals for aircraft to fill various pre-determined roles: heavy fighter, light bomber, heavy bomber and reconnaissance. For a bigger idea pool, Imperial Japanese Army (IJA) main aircraft providers, Kawasaki and Tachikawa, were invited to join the group, too. In that period projects such as Kogiken Plan III Revised light bomber and Kogiken Plan V Revised light bomber were designed and proposed to the IJA.
Among fighter designs the Kogiken Plan I Type A was a single seat heavy fighter and a Japanese adaption of the Bell P-39 “Airacobra” mid-fuselage engine concept. The aircraft was designed end 1941 and should be powered by a single Kawasaki Ha 40 liquid-cooled in-line engine, derived from the German Daimler-Benz DB 601A. The engine was installed immediately aft the cockpit driving a four-bladed puller propeller via an extension shaft. A tricycle landing gear was provided similar to the Bell P-39. Armament consisted of 37 mm Ho-203 or 20 mm Ho-5 canon firing through the propeller hub and two wing-mounted 12.5 mm Ho-103 guns. No further details are known, the project never left the drawing board (Ref.: Parts from Unicraft).

Kogiken Plan V Revised Light Bomber (Unicraft, Resin)

TYPE: Light bomber, fighter-bomber. Project

ACCOMMODATION: Crew of two

POWER PLANT: Two radial engines, rated at 1,450 hp each

PERFORMANCE: No data available

COMMENT: This design of a light bomber dates back to autumn 1941. A blueprint became available after the end of WW II showing a detailed three-view of the project and some important physical dimensions. It might be possible that this design may have had influence on the development of the Kawasaki Ki-102 (Allied code ‘Randy’). Furthermore, the design shows some similarity to the Grumman XP-50, forerunner of the Grumman F7F “Tigercat” (Ref.: 24).

Mansyu Ki-98 (A+V Models, Resin)

TYPE: Ground attack aircraft, fighter-bomber. Project

ACCOMODATION: Pilot only

POWER PLANT: One Mitsubishi Ha-211 Ru radial engine, rated at 2,200 hp

PERFORMANCE: 454 mph at 32.810 ft

COMMENT: In 1943 Mansyu offered the Japan Army Air Force a project of a single-seat ground attack aircraft designated Ki-98. The design was of twin boom configuration and was powered by a 2,200 hp turbosupercharged Mitsubishi Ha 211 Ru radial engine mounted in the central nacelle behind the pilot’s seat and driving a four-blade pusher propeller. Nose-mounted armament consisted of one 37 mm and two 20 mm cannon. A prototype was still under construction when Japan surrendered in September 1945 (Ref: 1)

Kogiken Plan III Revised Light Bomber (Unicraft, Resin)

TYPE: Light bomber. Project

ACCOMMODATION: Crew of two

POWER PLANT: Two radial engines, type not available

PERFORMANCE: No data available

COMMENT: Poorly documented JAAF-project of a light bomber with twin fuselage, two radial engines and pilot and gunner/radio-operator seated in the left fuselage. Similar designs during World War II were in Germany Arado E,580 (project), Messerschmitt Me 109Z (flown, Z for Zwilling = twin), Messerschmitt Me 308 (project),  Messerschmitt Me 609 (project), Dornier Do 635 (Junkers Ju 8-635) (project),and Heinkel He 111Z (flown), and in the United States North American P-82 (flown).

Kawasaki Ki-119 (Unicraft, Resin)

TYPE: Light bomber. Project

ACCOMMODATION: Pilot only

POWER PLANT: Mitsubishi Ha-104 radial engine, rated at 1,900 hp

PERFORMANCE: 360 mph at 19,685 ft

COMMENT: The Kawasaki Ki-119 was a design for a single-engine light bomber that would have been used in the defense of the Japanese homeland. Earlier Japanese bombers had been designed to operate over long distances, either in China or over the Pacific, but by the start of 1945 it was clear that the Japanese army might soon be fighting on home soil. This meant that a short range single-engine bomber would be possible, saving on the limited supply of both engines and trained air crew.
In March 1945 the Army Air Force issued Kawasaki with orders to produce a single seat bomber that could carry 1,764lb of bombs to targets 373 miles from its base, armed with two 20mm cannon and powered by one 1,900 hp Army Type 4 radial engine. Unlike many new aircraft being developed in Japan in 1945 the Ki-119 was not designed to be used in suicide attacks.
Takeo Doi and his team produced a design and a mock-up in three months. The fuselage was based on that of the Kawasaki Ki 100 radial-engine fighter. The aircraft was made as easy to fly as possible – a wide track undercarriage with good shock absorbers was chose to make the aircraft easy to handle on the ground, and large wings with a high aspect-ratio were designed, to make it easy to handle in the air. The aircraft was designed to carry three different sets of armament. In its basic light bomber role it was to be armed with two 20mm cannon and one 1,764lb bomb. It could also serve as a fighter escort, with no bombers but two extra 20mm cannons, or as a dive bomber with two 551lb bombs.
The impressively rapid development of the Ki-119 came to a halt in June 1945 when the detailed drawings were destroyed when American air raids damaged Kawasaki’s factory at Kagamigahara. This pushed back the expected delivery date for the prototype from September until November, with production expected in time for the new aircraft to take part in the fighting of 1946. The unexpectedly sudden end to the war meant that the prototype was never completed (Ref.: 24).

Kawasaki Ki-88 (Unicraft, Resin)

TYPE: Fighter, fighter bomber

ACCOMMODATION: Pilot only

POWER PLANT: One Kawasaki Ha-140 liquid-cooled engine, rated at 1,500 hp

PERFORMANCE: 373 mph at 19,685 ft

COMMENT: The Kawasaki Ki 88 was designed as a fighter aircraft and inspired by the Bell P-39 Airacobra. Work on the design began in 1942 and by 1943 a full-scale mock-up was completed. The engine was mounted behind the cockpit, driving a tractor propeller via an extension shaft. Proposed armament comprised a 37 mm cannon in the propeller shaft and two 20 mm cannon in the lower section of the nose. Calculation suggested no great improvement on that of the Kawasaki Ki-61 Hien already in production, and so the project was abandoned during 1943 (Ref.: 1).

Nakajima Ki-62 (Unicraft, Resin)

TYPE: Interceptor fighter. Project.

ACCOMMODATION: Pilot only

POWER PLANT: One Kawasaki Ha-40 liquid-cooled engine, rated at 1,175 hp

PERFORMANCE: 370 mph at 15,950 ft (estimated)

COMMENT: The Nakajima Ki-62 was a light fighter designed in 1941 to compete with the Kawasaki Ki-61 “Hien”. Although this design appeared to be promising, its development was discontinued to enable Nakajima to concentrate on production of their Ki-63 “Hayabusa” and Ki-44 “Shoki” fighters. Later, the Ki-62’s data and design features were incorporated in the Nakajima Ki-84 “Hayate” design (Ref.: 1).

Mitsubishi Ki-73 “Steve” (Unicraft, Resin)

TYPE: Long-range escort fighter. Project

ACCOMMODATION: Pilot only

POWER PLANT: One Mitsubishi Ha 203-II liquid-cooled engine, rated at 2,600 hp, driving three-bladed contra-rotating propellers

PERFORMANCE:  466 mph

COMMENT: During May 1943, Japanese authorities delivered a new requirement for a single-seat, single-engine long range escort fighter to protect bomber formations from interception by Allied warplanes beginning to gain the advantage in the skies over the Pacific Area of Action. The Mitsubishi Ki-73 was one result of the requirement by the type was not furthered beyond a sole, incomplete prototype before the end of WW II. The design team managed to find success with the earlier twin-engine Mitsubishi Ki-46 “Dinah” and eventually moved on to the promising Mitsubishi Ki-83 twin-engine, two seat long-range heavy fighter design of which four prototypes ultimately emerged when the development of the Ki-73 was abandoned. Rather unique for Japanese-originated wartime fighter design was the use of contra-rotating propeller arrangement. The rest of the overall design arrangement was conventional – the engine in the nose, a single-finned tail at rear and cockpit set over center mass. Wings were straight monoplane appendages with clipped tips and tailwheel undercarriage was fully retractable. While the Mitsubishi Ki-73 was never formally adopted for service and never entered serial production, captured documents by the  Allies – who believed the type was to come online soon – allocated the codename “Steve” for the series which never was.