Kawasaki Ki-64 – data


Republic XP-69 (US), Heinkel P.1076 (Germany), Caproni CA.183bis (Italy)

Type Fighter

Crew One


One Kawasaki Ha-201 ([Ha-72] 11), 24-cylinder, inverted-V, liquid – cooled engine developing 2,350hp at take-off, 2,200hp at 12,795ft, driving two, metal, 3-bladed contra-rotating propellers











Wing area



Wing loading

3.47 lb/m!


Power loading


4.8 lb/hp









Max speed



at 5,000m

at 16,405ft



621 miles


5 min 30 sec to 5,000m (16,405ft)




Fuel capacity

618 litres

136 gallons


Two 20mm Ho-5 cannons in the fuselage deck, one 20mm Ho-5 cannon in each wing


None. Only one Ki-64 was completed and flown before the end of the war.




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In August of 1942, the IJA saw a need for a air­craft that, in its primary role, would serve as an interceptor flying sorties to defend instal­lations, airfields and other assets that were considered important and therefore subject to enemy attack. Design specifications were drafted by the IJA for the aircraft and it was Kawasaki who put forth what they felt was the answer: the Ki-88.

Prior to drafting their design specifications, the IJA had sifted through a number of ideas before settling on a plane that had to have a heavy armament to ensure it could inflict sig­nificant damage to enemy aircraft, especially bombers, and also good handling character­istics to make it not only a stable gun plat­form, but also to avoid a steep learning curve for new pilots.

To this end, Tsuchii Takeo, a designer for Kawasaki, began work on what would become the Ki-88. Takeo selected a 37mm cannon as the primary weapon, supported by two 20mm cannons. It is probable that the 37mm Ho-203 cannon and two Ho-5 20mm cannons would serve as the armament fit with all three weapons fitted in the nose. Given the size of the Ho-203 (which was a lit­tle over 1.53m (5ft) in length, weighing 88.9kg (196 lb)), this presented a problem in squeez­ing them, along with the engine, into the
nose. To get around this, Takeo placed the l,500hp Ha-140 liquid-cooled, turbo- (or super-) charged engine in the fuselage, behind the cockpit. The three-bladed pro­peller was driven using an extension shaft that ran from the engine to a gearbox con­nected to the propeller. In essence, Takeo built the aircraft around the Ho-203.

The main advantage of placing the engine in the fuselage was that it allowed the cannon to fire through the propeller hub, producing a more stable firing platform that resulted in improved accuracy. Another advantage was that it allowed a skilful designer to make the nose more streamlined, enhancing speed performance.

A good number of references infer that Takeo’s design was inspired by the Bell P-39 Airacobra. While there is no evidence that specifically states that Takeo simply copied the American fighter, the P-39 was in limited operational use by the time design work began on the Ki-88 in 1942, notably seeing action in the Battle of Guadalcanal. Thus, the Japanese were aware of the design. Whether an example was ever captured for analysis is unknown but certainly intelligence was avail­able on the plane. Or, it may be that Takeo arrived at the same conclusion as did H. M. Poyer, designer of the P-39, when looking at
how best to accommodate a large calibre cannon in a single engine aircraft.

In June of 1943, Takeo finalised his design for the Ki-88. Apart from the use of a 37mm cannon and the engine placement, the Ki-88 bore no further resemblance to the P-39. The Ki-88 had a deep fuselage to accommodate the Ha-140 engine that was situated below and to the rear of the cockpit. The air scoop for the Ha-140’s radiator was mounted on the bottom of the fuselage, just forward of the wing roots. The radiator itself was positioned back from the scoop on the bottom interior of the fuselage, almost directly underneath the pilot’s seat. Jutting out on the left side of the fuselage, just above the trailing edge of the wing, was the scoop to provide air to the turbo – or super-charger of the Ha-140. The landing gear was conventional and the main gear retracted into the wings, while the tail wheel was fixed. A fuel tank was provided in each wing, mounted behind the wheel wells. On either side and to the bottom of the Ho-203 cannon were the Ho-5 cannons.

With the final design complete, work began on a full scale mock-up of the Ki-88 and this was completed sometime in 1943. In addition, work had already begun on con­struction of the fuselage and wings for a pro­totype and it was expected that by October
1943 the Ki-88 would be nearing completion. The IJA, however, had other plans for the Ki-88. After inspecting the mock-up and in reviewing the projected performance data of the plane, it was seen that it offered no real advantage over other designs then in opera­tional use, notably the Kawasaki Ki-61 Hien. Thus, Kawasaki was ordered to terminate all work on the Ki-88.

The Kamikaze Airplane

Kamikaze, which in Japanese means ‘divine wind’, was not a term used by the Japanese to reference their special attack units but came into common use in the West. Instead, shimpu and shimbu were more often used by both the UN and the IJA respectively. May 1944 would signal the beginning of dedicated suicide attack missions against the US and her allies. The effect of being on the receiving end of such attacks was horrific and would take its toll on US sailors.

A post-war report by the US Strategic Bombing Survey bluntly stated that kamikaze attacks were effective and given the situation for the Japanese, very practical. Statistics of sunk and damaged US ships during the Philippines campaign (October 1944 to Janu­ary 1945) showed that kamikaze attacks were far more effectual. Of course, being subjected to such attacks wreaked havoc on morale as well as a surge in mental illness. The US Navy, the focus of the majority of kamikaze attacks, saw such illness rise by 50 per cent in 1944 when compared to 1941. So bad was the problem that during the Okinawa campaign, the US Navy stopped warning crews that kamikaze attacks were to be expected as they only added to the sailor’s stress levels. General George C. Marshall wrote in a 1945 report to the US Secretary of War that, ‘The American soldier has a very active imagina­tion… and is inclined to endow the death­dealing weapons of the enemy with extraordinary qualities…’ And thus the ‘Kamikaze Airplane’ appears on the scene.

Following the close of World War 2, an illus­tration of an aircraft appeared in either Popu­lar Mechanics or Popular Science magazine. The aircraft, labelled a kamikaze plane, was a curious mixture of what appeared to be the tail of a Mitsubishi A6M Reisen, a fuselage not too unlike the Nakajima Kitsuka and a canopy similar to aircraft such as the Kawanishi NIKI Kyofu (meaning ‘Mighty Wind’ but known as Rex to the Allies) or the Nakajima Ki-84 Hay – ate (meaning ‘Gale’; Frank to the Allies). Even more curious was the fact that the aircraft used air-cooled radial engines, one in each wing, but in a pusher configuration.

The Kamikaze Airplane was said to have been sighted by some US Navy crew mem­bers as it flew over their ships. It was from

The Kamikaze Airplane – data

No specifications were provided for the aircraft. Deployment

None. The Kamikaze Aircraft was strictly fictional.

their descriptions that the illustration of the aircraft was created. The result was certainly unlike any plane then in the theatre but there is some precedent in terms of genuine air­craft being misidentified. One example was the ‘Kawasaki Type 97 Medium Bomber’ that was given the codename Julia. Because of very inaccurate illustrations of the plane that were derived from a written description, Julia was in fact the Kawasaki Ki-48 (Lily). It may very well be that the Kamikaze Airplane was actually a US Grumman F7F-2N Tigercat of which two US Marine Corps squadrons equipped with the plane began operating from Okinawa in September 1945. One was

VMF(N) 531 while the second was a photo reconnaissance unit. With the Tigercat being new to the Pacific Theatre, it can be surmised that some sailors and crew mistook the twin – engine Fighter for a Japanese plane and sub­sequently described something other than what was actually seen. However, the Kamikaze Airplane was written off as a spec­tre of the imaginations of sailors who had borne the brunt of kamikaze attacks.

Light reconnaissance bomber

In the late 1930s, a He 70 was imported to Japan. Few details are available but the wing form of the He 70 would later provide the influence for the wing design of the Aichi D3A1 carrier bomber, known to the Allies as Val.

Heinkel He 112B-0 fighter

In 1937, the UN was seeking new fighters to combat the increasingly modern aircraft being encountered in China. Heinkel was at the time looking to export the He 112, a design which was ultimately rejected by the Luftwaffe. The UN placed an order for 30 HE 112B-0 fighters, known in Japan as the A7Hel Type He Air Defence Fighter. 12 of the 30 were delivered though Japanese pilots disliked the performance of the plane and mechanics had difficulties maintaining the liquid-cooled engines. As Japanese fighters of improved capability were entering service, the He 112B-0 never saw combat and the Japan­ese cancelled the remaining 18 aircraft. Ser­viceable He 112B-0 were used as instructional aircraft and as means to study German manufacturing techniques. Figuring the He 112B-0 was in active service, the Allies codenamed the aircraft Jerry although it was never encountered.

Heinkel He 118 dive bomber

With the Luftwaffe uninterested in the He 118, Heinkel found the Japanese receptive to the plane. The UN placed an order for a sin­gle He 118 to be delivered by February 1937 along with the licence to manufacture the He 118 in Japan. The IJA also purchased a sin­gle He 118 for delivery by October 1937. Known in Japan as the DXHel, Hitachi Seisakusho was to be the company that would produce the licensed aircraft. The He 118 V4 was shipped to Japan and assem­bled at Yokosuka for the UN, but during a test flight it broke up in the air and the UN aban­doned the plane. The IJA received the He 118 V5 months later but it too lost interest and Heinkel received no further orders.

Junkers G 38/K 51 heavy bomber

The Army sought to have their own version of the Junkers massive G 38 airliner and in September 1928, Mitsubishi entered into a contract with Junkers for the design specifi­cations, blueprints, manufacturing data and licence to build the aircraft as a bomber, known as the К 51, the export version of the G 38. Mitsubishi sent designers to Germany in 1928 to study the G 38 and production tech­niques, and by 1930, the necessary tools, jigs and material were imported and in place. Junkers sent a team of engineers to Japan to assist with the production. The first bomber, the Ki-20, was completed in 1931. A total of six were built from 1931 to 1935. Kept in secret, the general public was not made aware of the Ki-20 until 1940 when three Ki-20s partici­pated in a parade fly-over. The Ki-20 did not see action.

Junkers К 37 bomber

A single К 37 bomber was imported through Sweden and was donated to the Army as Aikoku-1. Used during the Manchurian Inci­dent, the Army was impressed with the К 37 and in 1932 asked Mitsubishi to make a simi­lar bomber. Using the К 37 as a basis and cap­italising on experience from the Ki-20, the prototype Ki-1 heavy bomber was completed in March 1933. Despite problems with the engines, the Ki-1 was adopted to replace the old Type 87. The Ki-1-II soon appeared in an attempt to fix issues with the Ki-1 but it was not liked by the crews that flew it. Another air­craft, the Ki-2 light bomber, was also built using the К 37 as a basis. The Ki-2 and later Ki-2-ІІ (both being built from 1933 to 1938) proved very successful, seeing action in China and later as trainers into the late 1930s. The Allies thought the КІ-2-ІІ was still in ser­vice when the war began and assigned it the codename Louise.

. Kawasaki Ki-88 – data

. Kawasaki Ki-88 - data

image11Performance (specifications are estimations by Kawasaki)

Max speed at 19,685ft 600km/h 373mph

Range 1,198km 745 miles

Climb 6 min 30 sec to 5,000m (16,404ft)

Ceiling 11,000m 36,089ft


One 37mm Ho-203 cannon and two 20mm Ho-5 cannons


None. The Ki-88 did not progress past a mock-up and partially completed prototype.


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This story centres on the failure of a bomber that inspired the development of another new type. The Nakajima Ki-68 and the Kawanishi Ki-85, both four-engine, long – range bomber designs, hinged on the success of the UN’s Nakajima G5N Shinzan (Mountain Recess). The G5N would prove to be a failure and in turn led to the termination of the Ki-68 and Ki-85 programs; therefore the IJA was left without a long-range bomber project. It was Kawasaki who stepped in to fill the gap with their own design.

In 1938, the UN was enamoured with the idea of a bomber that was capable of operat­ing up to 6,486km (4,030 miles) from its base. In part, this was due to the initial desire to strike targets deep in Russia from Manchurian bases. Later, when Japan went to war with the United States, a need to attack the US mainland was identified and it was recog­nised that a two-engine design would not suf­fice – four engines would be required. On the understanding that the Japanese aircraft industry had very little experience in building such aircraft, the UN used the Mitsui Trading Company as a cover to acquire a Douglas DC-4E four-engine airliner, ostensibly for use by Japan Air Lines. The development of the

DC-4E four-engine passenger aircraft was funded by five airlines and Douglas with United Airlines building and testing the one prototype. While the DC-4E was impressive, in terms of its operating costs it did not add up. The aircraft was complex and this resulted in maintenance issues, which increased the cost of using the plane. Support for the DC-4E was withdrawn and Douglas was asked to simplify the design. As a conse­quence, the DC-4 saw operational use with the US Army as the Douglas C-54 Skymaster.

In early 1939, the sale of the DC-4E was completed and arrived in Japan to be reassembled. By this time, the UN had informed Nakajima to be ready to study the DC-4E to produce a suitable bomber devel­opment from it. After having been flown sev­eral times, the DC-4E was then reported as having ‘gone down in Tokyo Bay’, but in real­ity had been handed over to Nakajima whose engineers took it apart. Within a year, Naka­jima had built the prototype G5N1 which first flew on 10 April 1941. The G5N1 used only the landing gear layout, wing design and radial engine fittings from the DC-4E coupled to a new fuselage, tail design and a bomb bay. The IJA planned to produce the G5N1 and

Nakajima submitted the Ki-68 version using either the Mitsubishi Ha-101 or Nakajima Ha-103 engines in place of the Nakajima NK7A Mamom 11 units on the G5N1. Kawan­ishi also submitted their Ki-85 which was to use the Mitsubishi Ha-111M engines.

As it was, the G5N1 proved to be a dismal failure. The NK7A engines were problematic and underpowered and the aircraft was too heavy and complex. These difficulties con­tributed to the overall poor performance of the G5N1. Despite the problems, three more G5N1 aircraft were built followed by a further two air­craft that replaced the NK7A engines for four Mitsubishi Kasei 12 engines. The two addi­tional aircraft were designated G5N2, but even the Kasei 12 engines could not resuscitate the design and the problems remained. Due to its complications, the G5N1 was never used as a bomber. Two G5N1 (using Kasei 12s) and two G5N2 aircraft were converted to transports and served in this role until the end of the war. The Allies gave the G5N the codename Liz.

By May 1943, the cancellation of the G5N had also brought the demise of both the Ki-68 and the Ki-85 (of which Kawanishi had a mock-up constructed by November 1942), leaving the IJA with no active four-engine

bomber designs on the table. Kawasaki, see­ing the opportunity, immediately got to work on designing a new bomber. The man behind the Ki-91 was Takeo Doi, an engineer employed by Kawasaki. It was his goal to see the development of a successful four-engine

bomber and engineer Jun Kitano would work with Doi to help turn the aircraft into reality. In June 1943, Doi and Kitano began their initial research and by October, work on the first design concept for the Ki-91 was underway.

The Ki-91 was slightly larger than the Boe­
ing B-29 Superfortress which was to be mass produced in late 1943. Four Mitsubishi Ha-214 18-cylinder radial engines were chosen to power the Ki-91. As the plane was expected to operate at high-altitude, provisions were made to utilise superchargers with the

engines and the projected maximum speed was 580km/h (360mph). To provide for the anticipated 10,001km (6,214 mile) range, each wing carried eight fuel tanks with a fur­ther two mounted in the fuselage above the bomb bay. For weapons, the Ki-91 was to carry a heavy armament of twelve 20mm can­nons. Five power-operated turrets were to be used; one in the nose, one on the underside of the forward fuselage, one above and below the aft portion of the fuselage, and the last in the tail. The bottom turrets were remotely controlled while the remainder were manned. The tail turret was to mount four cannons while the rest had two cannons each. As far as bombs, a total payload of 4,000kg (8,8181b) was envisioned and the Ki-91 was to have a tricycle landing gear with the nose gear using a single tyre and the main landing gear using dual tyres. A semi – recessed tail wheel was also installed.

Another feature of the Ki-91 was to be the use of a pressure cabin for the eight man crew. But the development of such a large pressurised cabin for the Ki-91 was expected to take some time to implement, even using knowledge from another of Doi’s designs, the Kawasaki Ki-108, a twin-engine high-altitude fighter fitted with a pressure cabin for the pilot. Therefore, it was decided that the initial Ki-91 prototype would be built without pres-
surisation so as to avoid holding up develop­ment and allow its flight characteristics to be measured. Once the pressurised crew cabin for the Ki-91 was ready, subsequent aircraft were to have it installed.

In April 1944, a full-scale wooden mock-up was completed and Kawasaki invited IJA offi­cials to come and review the Ki-91. Up until this time, the project was a private venture by Kawasaki to which considerable company resources has been allocated. If the IJA did not find the bomber to their liking, it would have been a waste of time, effort and money. Fortunately, the IJA saw potential in the Ki-91 and work continued. In May, the IJA inspected the Ki-91 mock-up and immedi­ately ordered production of the first proto­type. Kawasaki planned to construct the Ki-91 at a new plant in Miyakonojo in Miyazaki Prefecture. However, the IJA did not want to wait for the construction of a new plant and directed Kawasaki to use their established factory in Gifu Prefecture. By June 1944, the construction of the prototype Ki-91 had begun at the Gifu factory, together with the necessary tools and jigs to produce further aircraft.

However, June would see the first B-29 raids over Japan, but as the attacks were few and far between, work on the Ki-91 continued despite the worsening situation for the coun­
try. This would change by the close of 1944 when B-29s began to operate from the Mari­ana Islands and by 1945 bombing raids were far more frequent. In February 1945, a raid heavily damaged the factory in which the Ki-91 prototype was being constructed. The damage was extensive, ruining the tools and jigs. With the loss of equipment needed for future production coupled with dwindling supplies of aluminium, the IJA decided that fighters to combat the marauding B-29s had become a higher priority than bombers. Any hope of utilising such bombers was at best slim. With the Ki-91 at 60 per cent comple­tion, Kawasaki stopped further work on the bomber and the project was officially can­celled in February 1945.

Had the Ki-91 achieved service, plans to attack the US mainland were in place to oper­ate the bomber from the Kurile Islands using temporary bases, while another plan to strike Hawaii was formulated using bases in the Mar­shall Islands. The second plan was rendered obsolete when the Japanese lost the Marshall Islands to the Allies in February 1944. As a note, contemporary images sometimes show the Ki-91 as having a bomb bay battery of down­ward firing cannons for a ground-attack role. While the Japanese were interested in such concepts, there is no evidence that Kawasaki envisioned such a task for the Ki-91.

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Mitsubishi T. K.4 Type 0

At the outset of hostilities in the Pacific, Amer­ican intelligence had very little information on just exactly what aircraft the Japanese were fielding. In part this lack of knowledge sprang from poor intelligence management and cen­sorship of periodicals and other publications by the Japanese authorities. In scrambling to document Japanese aviation, invariably US intelligence officers turned to Japanese mag­azines as a means of gaining information. However, there were pitfalls to using such sources and the Mitsubishi T. K.4 Type 0 was just one example.

The T. K.4 appeared in a section of the Japanese aviation magazine Sora entitled ‘Dreams of Future Designers’. The issue was published in April 1941. The T. K.4 was depicted as a twin-engine fighter whose design was rather similar to the German Messerschmitt Bf 110. The aircraft, although a fighter, was shown with a glazed nose along with the expected glazing over the pilot and crew positions. Each of the low mounted wings sported an inline engine in a very streamlined cowling, each motor driving a three-bladed propeller. What weapons the T. K.4 carried was unknown nor was the crew compliment listed, although two or three could be estimated. Also lacking was any data on the performance of the T. K.4.

Information on the T. K.4 would also appear in a US magazine. The 25 December 1941 issue of Flight mentioned the aircraft as a twin-engine, twin-tail monoplane fighter. From these sources, the US intelligence determined that the T. K.4 was a bona fide fighter that would be encountered in combat. Major Frank T. McCoy, Jr., the head of the Material Section of the Directorate of Intelli­gence, Allied Air Forces, Southwest Pacific

Area, would assign the T. K.4 the codename Frank, taking his own first name. It was McCoy who arrived at the method of assign­ing names to Japanese aircraft in order to simplify identification.

At some point, the T. K.4 Type 0 fighter took on a completely different appearance. When the Japanese Aircraft Manual, O. N.l. 249 (Office of Naval Intelligence), was first pub­lished in December 1942, the Mitsubishi Type 0 was no longer called the T. K.4. Although no illustration was provided in the manual, the Type 0 was described as an army fighter based on the Dutch Fokker D. XXIII. The D. XXIII was a twin-engine fighter that mounted the engines in the fuselage in a push-pull configuration. It was also a twin – boom design that was under development and in flight-testing until the German inva­sion. The manual stated that the Type 0 used two German BMW engines, each developing 750hp, but that a redesign of the aircraft would see it using two l,000hp Mitsubishi Kinsei air-cooled radial engines. No further information was made available.

When the original T. K.4 Frank failed to materialise in combat, McCoy removed his name from the T. K.4 and reassigned it to the Nakajima Ki-84 Hayate (meaning ‘Gale’) which was a fighter very much in use, being first encountered in combat in early 1944. The Type 0, as described in the O. N.l. 249 manual, was given the codename Harry after Colonel Harry Cunningham, a friend of McCoy’s, who was the intelligence officer for General Ennis Whitehead. At the time it was believed that the Type 0 would eventually be seen in action but, just like the T. K.4, it never would and the Type 0 was dropped from the intelligence publications.

The T. K.4 was not the only Japanese aircraft uncovered in the pages of Sora. The same ‘Dreams of Future Designers’ article in which that image was unearthed also included the Nakajima AT27. Several months later, the 25 December 1941 issue of Flight, a US maga­zine, would also feature these planes, along with several others, lending credence to the idea that they were genuine aircraft in use by the Japanese.

The AT27 was novel in a number of ways. On the outside, the fuselage was sleek and well streamlined. The wings were low-mounted with a conventional tailplane. Inside, however, the AT27 featured two 12-cylinder inline engines each rated at 1,250hp and was reported to obtain a maxi­mum speed of 660km/h (410mph). One engine was in the nose while the other was situated behind the cockpit. Contra­rotating propellers were used, the rear engine driving its propeller via an extension shaft. To maintain the excellent aerodynamic prop­erties, the engines were reported to have been provided with a ‘steam cooling’ system. This may have been a surface evaporation system. Such a system took the steam created after the water had passed through the engine and ran it through piping in the wings where the cooler airflow would con­dense the steam back into water that was cycled back through the engine. The pilot
was afforded some protection by the engines in front and behind him but the AT27 could also carry additional armour not only for the pilot but for the engines as well. What type of weapons the AT27 was to carry were not known.

Based on its appearance in the magazines, the AT27 was believed to be a bona fide fighter that could be encountered and thus Allied intelligence gave the AT27 the code – name Gus. However, the AT27 would never be seen or met in battle since, as was later discovered, the aircraft was Fictitious. Gus was soon dropped from the Japanese aircraft intelligence rolls.

Interestingly, the AT27 was very similar to the very real Kawasaki Ki-64 whose develop­ment began in October 1940. Both used 12- cylinder inline engines, one in the nose and the other behind the cockpit, driving contra­rotating propellers. In addition, both used a surface evaporation system. Perhaps by sheer coincidence, one of the Japanese illus­trations of the AT27 that was published in Sora and later in Flight showed it sporting the number 64 on the fuselage.

The З-view illustration of the AT27 is in the markings and colouration of an aircraft of the 244th Sentai operating in the defence of Tokyo, 1944-1945. The side view below depicts the AT27 as it appeared in Sora magazine."


As we have already seen, the April 1941 issue of Sora misled Allied intelligence over the nature and extent of Japanese aircraft design. As the war continued, none of the four aircraft that feature in the April issue were encoun­tered and subsequently dropped from Allied intelligence publications. However, Sora con­tinued and so did the section responsible. How often the ‘Dreams of Future Designers’ portion of the magazine appeared is not known but one issue from either 1944 or 1945 contained a design that was nothing short of fantastic. This was the S-31 Kurowashi, or Black Eagle.

The Kurowashi was a four-engine heavy bomber concept. What was unique about the aircraft was that all of the engines were housed within the fuselage and the Kurowashi used a push-pull configuration. Both in the front and the rear of the fuselage were two 2,500hp, 24-cylinder, liquid cooled, inline X-engines, driving a pair of contra-rotat­ing, three-bladed propellers via a gearbox. With this powerplant the Kurowashi was to boast a top speed of 689km/h (428mph), but such a powerful engine of this type would not see service with the Japanese air forces. However, this was not for a lack of trying: it may or may not be that the originator of the Kurowashi was aware of the Yokosuka YE3 series of engines.

In 1940, the UN initiated development of the YE3A, a 24-cylinder, liquid-cooled, X-engine that was to produce 2,500hp. An X-engine is produced by having paired V – block engines horizontally opposed to each other with the cylinders in four banks driving a common crankshaft and thus, when viewed head-on, appearing as a ‘X’. The major benefit to using such a configuration is that the engine is more compact than a com­parable radial engine or standard V-engine. However, X-engines are far more complex to construct and service and are heavier. It was not be until October 1943 that the first YE3B [Ha-74 Model 01] (also known as the Ken No. l) was completed and tested. The YE3B was designed to be housed inside the wing. A second model, the YE3E [Ha-74 Model 11) (Ken No.2), was rated at 3,200hp and was slated to be completed in March 1944. Unlike the YE3B, the YE3E was designed to be housed within the fuselage. As it was neither engine would see service by the time the war ended. Interestingly, a surviving YE3B engine was fitted with a two-stage reduction gear and a extension shaft that would have been used to drive two, contra­rotating propellers.

With a wingspan of just over 33m (107ft), the Kurowashi was by no means a small air­craft. The plane was just under 21m (70ft) in length and a height just shy of 6m (20ft). These dimensions were very similar to the Boeing B-l 7 bomber. The Kurowashi sported horizontal stabilisers which ended in ovoid shaped vertical stabilisers.

The Kurowashi was certainly not lacking for weaponry. A total of eight 7.7mm machine guns and four 23mm cannons were carried by the bomber. 7.7mm was a calibre used by both the IJA and the UN, but on the other hand, the Japanese did not field a 23mm can­non in any form, either in aircraft or on the ground. The UN did use a 25mm anti-aircraft cannon (Type 96) but did not apply the weapon to aircraft. The IJA also experi­mented with a 25mm aircraft cannon but abandoned it in favour of the 30mm cartridge. Why the creator of the Kurowashi decided to use 23mm as the calibre for the cannons remains unknown.

What is known is the novel arrangement of the defensive armament. Fitted directly into the leading edge of each wing were two ball turrets. The outer turret contained one 23mm cannon while the inner turret sported two 7.7mm machine guns. Directly opposite these front-facing turrets was another set of ball turrets. As the trailing edge of the wing was too thin to allow the turrets to be inter­nally mounted, each turret was fitted into the end of a nacelle that extended from the back of the wing. Therefore, each wing was fitted with four turrets for a total of two 23mm can­nons and four 7.7mm machine guns. To con­trol these turrets the Kurowashi relied on two gunners, the bombardier and co-pilot. Both gunners had positions facing to the rear of the aircraft behind the bomb bay. The first gunner station was in the upper portion of the fuse­lage while the second was in a ventral station. Weapon sights were provided along with the controls to manipulate and fire the turrets. The bombardier and the co-pilot stations were also provided with a sight and turret controls so that if they were not occupied with other duties they could man the weapons. It is likely that the bombardier and co-pilot had control of the forward facing tur­rets while the two gunners maintained con­trol over the rear facing weapons.

For its war load the Kurowashi could carry just over 7,257kg (8 tons) of bombs, about 1,814kh (2 tons) less than the Boeing B-29. The bomb bay was divided into two and each section could hold six bombs to give a total of twelve. Beneath the main bomb racks were

hinged panels, one per side. Each panel held four bombs for total of eight. When the bomb bay doors opened, the bombs suspended from the panels would be released and the panels swing aside so the remainder of the bombs could drop. This arrangement was created to maximise the payload space avail­able. Situated directly above the bomb bay were fuel tanks and it was likely the wings also housed fuel.

The Kurowashi used a tricycle landing gear system with the nose wheel retracting into the fuselage while the main landing gear went up into the wings. However, because of the heavy tail and to prevent damage to the rear propellers while on the ground or during take-off and landing, a large, retractable tail wheel was fitted to the back of the fuselage.

For its crew the bomber had five men: pilot, co-pilot, bombardier and two gunners. One of the gunners served as the radio operator as the radio station was situated in front of the upper gunner’s position.

It may very well be that Allied intelligence was aware of this design and it was also likely that by 1944-1945, intelligence officers were no longer taking aircraft illustrated in the ‘Dreams of Future Designers’ section in Sora magazine at face value. The Kurowashi was a creation that would have been very difficult to execute in reality and may not even have been feasible.

S-31 Kurowashi – data


Daimler-Benz Schnellbomber mit DB P83 Gruppenmotor (Germany)


Heavy Bomber



Powerplant Four 24-cylinder, liquid-cooled X-engines, each developing 2,500hp, each pair driving two, metal 3-bladed contra­rotating propellers


Span Length Height Wing area





107.7ft 69.2ft 19.3ft 1,431.6ft2






Max speed



Cruise speed



Landing speed





3,666 miles




Fuel Weight




Eight 7.7mm machine guns and four 23mm cannons (see text for arrangement); up to 8,000kg (17,6361b) of bombs

Deployment None. The S-31 Kurowashi was purely a paper, if not impractical, design in a magazine.

Junkers Ju 90 transport

On 25 July 1938, Mitsubishi entered into nego­tiations with Junkers on behalf of the IJA to work with the German company to produce a bomber version of the Ju90 transport. Ten were to be completed and flown to Japan. The IJA even allocated the designation Ki-90 for the bomber. However, Junkers eventually declined Mitsubishi’s proposal citing its involvement in filling domestic orders for air­craft.

Junkers Ju 160 transport

The Ju 160 was an improved Junkers Ju60, the latter having lost to the Heinkel He 70 in the fast, small airliner market. Lufthansa pur­chased 11 Ju 160A-0 and 10 Ju 160D-0 6-pas – senger aircraft, putting them into service in 1935-36. Two would end up in Manchuria, registered as civilian aircraft. The UN pressed them into service as the LXJ.


The D. IX provided the inspiration for the Seishiki-1 which used an imported Mercedes Daimler lOOhp engine, later licence-built in Japan. The Seishiki-1 was completed in 1916 but the biplane’s poor performance resulted in further development being cancelled.

Rohrbach R flying boat

The Navy was very interested in the metal air­craft construction techniques used by the German company Rohrbach. Mitsubishi was asked to study the techniques and the two companies would form Mitsubishi-Rohrbach GmbH in Berlin in June 1925. A total of three Rohrbach flying boats were to be imported, the R-l, R-2 and R-3, known collectively as the Mitsubishi Experimental Type-R flying boats. Although these aircraft would prove to have poor take-off and alighting that denied them military service, they did provide invaluable experience to Mitsubishi when it came to metal stressed skin construction.

Kayaba Katsuodori


The Katsuodori depicted here is shown in the colours and markings of the 71st Sentai. It is intercepting Tokyo-bound Northrop B-35 bombers of the 44th Bomb Squadron, 40th Bomb Group operating from Tinian.



Kayaba envisioned that his design for a fast, point defence interceptor would sweep through the Allied bombers like the kat­suodori bird hunts for fish. Impressed with the prowess of the katsuodori, Kayaba named his design after the bird. But as we will see, his vision was to meet with a harsh reality.

The genesis of the Kayaba Katsuodori began as far back as 1937 with the Kayaba Ramjet Study Group, a collection of engineers and scientists who sought to investigate ram­jet propulsion in Japan. The concept of the ramjet was actually patented in 1908 by French engineer Rene Lorin, but it was the Russian I. A. Merkulov who first built and tested one, the GIRD-04 in 1933. A ramjet is a very basic engine with few moving parts. In simple terms, it uses the high pressure air generated by the aircraft’s forward motion and forces it through the inlet. The air is then mixed with combusted fuel – this heats the air and is forced out of the rear of the engine, pro­viding forward propulsion. Unlike pulsejets (which were to be used on the Kawanishi Baika, see Page 61), the fuel flow is continu­ous. Without getting into the specifics of a ramjet, adjustments in the design of the inlet (to maximise the intake of air), combustor (to ensure effective operation during flight move­ments) and the outlet nozzle (to effect accel­eration increases) all come into play on
designing such an engine. The main draw­back with a ramjet engine is that at subsonic speeds its performance is poor. Below 612km/h (380mph), a ramjet suffers signifi­cant loss in speed and becomes highly ineffi­cient in terms of fuel consumption. The ramjet typically requires another power source to bring the aircraft up to the speed at which the ramjet can operate efficiently. Typ­ically, this speed is at least 966km/h (600mph). Once the ramjet reaches that speed the engine is self-sufficient and, with­out fuel injection moderation, would propel the plane to speeds far in excess of the design’s ability to handle the high tempera­tures and Mach number.

The Kayaba Ramjet Study Group saw the benefits of high speed with a relatively easy to manufacture engine. The group produced two test models before the final product, the Kayaba Model 1 ramjet, was realised. The Model 1 was projected to be able to offer speeds of 900km/h (559mph). With the engine complete, all that was needed was the aircraft to fit it into.

The airframe design began with Kumazo Hino. Hino was an officer in the IJA and had been the first Japanese to unofficially make a flight on 14 December 1910 when he acci­dentally took to the air in a Hans Grade mono­plane while he was taxiing. This aircraft had
been purchased from Germany. His interest in aviation saw him produce four aircraft designs: the Hino No. 1, No. 2 and the No. 3 and No. 4 Kamikaze-go airplanes. However, each of these designs was a failure. Pressure from his military superiors saw Hino give up on aviation by 1912.

However, in 1937, Hino was inspired to cre­ate a tailless glider. The project was taken over by the Kayaba Seisakusho (Kayaba Man­ufacturing Works) and then by Dr. Hidemasa Kimura who worked for the Aeronautical Research Institute of the Tokyo Imperial Uni­versity under Dr. Taichiro Ogawa. The result was the HK-1. The HK-1 (standing for Hino Kumazo) was built by the Ito Нікбкі K. K. and was completed in February 1938. It was purely a research glider to test the tailless concept. Testing commenced in December 1938 with ground towing at Kashima in Ibaraki Prefecture and the first air released flights began in September 1939 at Tsu – danuma in Chiba Prefecture. Because it showed positive results, the IJA took an inter­est in the concept. The HK-1 was purchased by the Rikugun Kokugijutsu Kenkyujo in April

1940 for continued testing. However, a subse­quent test flight on 16 April by an IJA officer pilot resulted in a hard landing that damaged the HK-1 beyond repair. In all, 182 flights had been made in the HK-1.

With the IJA still interested, the Rikugun Kokugijutsu Kenkyujo set aside 200,000 yen to continue the project. Kimura, along with Kayaba’s chief development designer Dr. Shigeki Naito, set about the task of producing a new tailless aircraft, this time with a possi­ble military application. The result was the Ku-2. The Ku-2 had no tail but rudders were fixed to the wing tips and the design was tested extensively from November 1940 through to May 1941 making 270 flights in all before it was damaged in a crash on 10 May. To further test the concept, Kimura (with the aid of Joji Washimi) produced the Ku-3 which had no vertical control surfaces at all and fea­tured a cranked delta wing form to test vari­ous angles of sweep. The only control came from the flaps arranged along the wings. 65 flights were carried out with the single Ku-3 before a crash in 1941 wrecked the glider.

The last design put forward by Kimura was the Ku-4. At the request of the Rikugun Kokugijutsu Kenkyujo, the Ku-4 was to be powered and a rear mounted 120hp de Hav – illand Gipsy 4-cylinder, air-cooled, inline engine was selected, turning a two-bladed propeller. Unfortunately for Kimura, the IJA lost interest in the entire concept. With the loss of the Ku-2 and the Ku-3, the IJA can­celled the Ku-4 before it could be finished. With no backing, Kayaba could not afford the 100,000 yen to finish the Ku-4 alone. The IJA had paid Kimura and Kayaba 17,000 yen out of the 200,000 yen project money for costs associated with the Ku-2, Ku-3 and what was already paid into for the Ku-4. The remaining funding was not released. Shiro Kayaba, how­ever, still had hopes that the concept could be a potent weapon and from this came the Kat- suodori.

The roots of the Katsuodori come from the Ku-2. Unlike the Ku-2, the wings were moved higher on the fuselage and the wing form had a rearward sweep. The Katsuodori retained the vertical wingtip rudders used on the Ku-2. The ramjet filled most of the fuselage which meant there was no room for landing gear. Instead, a main skid was incorporated on the underside of the fuselage along with a small wheel mounted at the rear of the aircraft. Without integral landing gear, the Katsuodori was to be fitted with a simple, sprung set of landing gear that could be jettisoned when the aircraft took to the air. The pilot sat towards the front of the fuselage and was pro­vided with a one piece canopy that offered respectable visibility to the front and sides.

In order to get the Katsuodori off the ground, Kayaba envisioned the use of four rocket booster units. Secured to each side of the fuselage under the wings were two rocket units and together all four could provide an estimated 7,200kg (15,8731b) of thrust. The planned procedure for using the rockets was to have one on each side being fired first, and when these had burned out the next pair would be fired. Each rocket contained pro­pellant for five seconds of thrust and, all told, the scheme would give the Katsuodori a total of ten seconds of thrust with which to get the plane off the ground and the ramjet function­ing. Kayaba estimated that the Katsuodori would need to achieve 367km/h (228mph) before the ramjet would operate and cer­tainly the speed provided by the rocket units would have been sufficient for this to happen. The rockets, once used, may or may not have been releasable but the latter is likely in order to minimise drag.

With the ramjet operating, the estimated performance of the Katsuodori was a speed of 900km/h (559mph) and a climb rate of three minutes to reach an altitude of 10,000 (32,808ft). Fuel load was 1,500kg (3,3061b) and with a fuel consumption of 50kg (1101b) per minute would grant a combat endurance of thirty minutes. Once the fuel was exhausted, the Katsuodori would use its glid­ing properties to return to base.

For weapons, Kayaba planned on mount­ing two 30mm cannons externally, one under each wing near the wing root. Kayaba did not wish to use existing 30mm cannon designs such as the Ho-155 preferring to produce a 30mm version of the 40mm Ho-301 cannon which his manufacturing facilities were con­structing for use in the Ki-44-П Hei Shoki fighter. The Ho-301 used caseless ammuni­tion with each round being, in effect, a rocket. The propellant cavity was partially lined with a thin aluminium cap. When the primer was struck, the propellant was ignited and the pressure would build up until the cap burst, the exhaust gas being vented out the back of the round to move the projectile forward. The main advantage of the weapon was its light weight for such a heavy calibre.

The design of the Katsuodori was nearly complete by 1943 and Kayaba anticipated that he could have had a flying prototype by

1944. By this time, however, the IJA was already involved with the rocket powered Ki-200 (the IJA version of the UN’s Mitsubishi J8M1 Syusui – see Page 96) and so paid no attention to the Katsuodori. Kayaba, in trying to salvage the design, stated that he could adapt the Katsuodori to accept the Kugisho Ne20 turbojet or the KR10 rocket motor as used in the Ki-200. And since his design was

nearly complete a prototype Katsuodori could be ready for testing before the Ki-200.

The advantages of the Katsuodori included a ramjet that was far less complex to con­struct than a turbojet. This would have been a critical asset in a Japanese war industry that was devastated by US bombing. It could also use standard aviation fuel, unlike the Ki-200 that required special fuels, and by extension, could operate from any airfield without the need of special fuelling apparatus and proce­dures. While the speed of the Katsuodori was on par with the Ki-200, the Katsuodori’s com­bat endurance was far superior to the Ki-200 and the IJA’s own planned rocket intercep­tor, the Rikugun Ki-202 Sytisui-Kai (see Page 40).

However, the Katsuodori had several draw­backs. The first was the use of the rocket boosters to get the plane up to speed. The Japanese did not have a successful track
record for using such units. Improper place­ment of rocket boosters was the reason behind the aborted second flight of the Naka – jima Kitsuka (Page 114), heavily damaging the aircraft. Attempts to use rocket boosters on the Mitsubishi Ki-109 to boost take-off and climb met with such poor results that the rockets were removed from the Ki-109 devel­opment all together. A misfire or variation in the thrust output might result in the plane careering out of control. Like the Ki-200, once fuel was exhausted the Katsuodori lost its speed advantage, and on the ground its recovery would take longer since the Kat­suodori could not move on its own without means of wheeled apparatus. This made it vulnerable to intruder aircraft dedicated to airfield interdiction missions. Kayaba’s elec­tion to use a 30mm version of the Ho-301 can­non would have been a recipe for disaster. The 40mm version, as used in combat by the

Japanese, had an incredibly short range – only 149.5m (490ft) since it had a muzzle velocity of 241m/sec (790ft/sec). Coupling the very short range of such a weapon with a high closure rate due to the speed of the Kat­suodori against a slow bomber, the pilot would have had mere seconds or less to line up the target, fire, and then bank to avoid col­lision. Since Kayaba did not proceed with a 30mm variant of the Ho-301, the muzzle velocity for the round is unknown but it can­not have been substantially more than the Ho-301.

Despite the potential advantages over the Ki-200, the Katsuodori would never see life outside plans on Kayaba’s design board. The IJA was looking to the Ki-200 and their own Ki-202 for their interceptor needs and thus ended Kayaba’s dream of seeing his Kat­suodori taking to the skies to defend Japan.

Kayaba Katsuodori – data




Handley Page H. P.75 Manx (UK), BOK-5 (Russia), Blohm und Voss P.210/P.215 (Germany), Heinkel P.1078 (Germany), Northrop XP-56 Black Bullet (US), Northrop XP-79 Flying Ram (US), Skoda-Kauba SK P.14.01 (Germany), Lippisch Li Р. ІЗа (Germany), Messerschmitt Me P. l 101L (Germany), Heinkel He P.1080 (Germany), Stockel Rammschussjager (Germany), Leduc Model 010 (France), Kostikov 302 (Russia)


Point Interceptor




One Kayaba Model 1 (or possibly later) ramjet producing 300kg (661 lb) of thrust at 367km/h (228mph), 420kg (925 lb) of thrust at 490km/h (304mph), 550kg (1,2121b) of thrust at 612km/h (380mph) and 750kg (1,6531b) of thmst at 734km/h through 1,103km/h (456mph through












Wing area



Wing sweep










Max speed



Landing speed





248 miles


3 min to 10,000m (32,808ft)





Two 30mm cannon


None. The Katsuodori did not advance beyond the drawing board.



Т. К.19

It was difficult for the US and her Allies to acquire intelligence about the Japanese war industry as far as HUMINT (HUMan INTelli – gence) was concerned. This was due to the relative difficulty associated with either turn­ing a Japanese source or inserting a foreign spy into Japan who was capable of avoiding detection. Once it was broken, the PURPLE code (as used by Japanese foreign offices) and the later JN-25 code (as it was labelled by the US) used by the 1JN provided a wealth of information and intelligence, but human intelligence and cipher cracking were only a part of the overall processes. One avenue used prior to the war was the gathering of publications such as books and magazines. Besides being relatively innocuous to pur­chase in Japan, such sources could be obtained outside of Japan and were therefore easier to gather. It was one such publication issued just prior to the start of hostilities that revealed the T. K.19 to intelligence officers.

The illustration of the T. K.19 appeared in the April 1941 issue of the Japanese aviation magazine Sora in a section entitled ‘Dreams of Future Designers’. The T. K.19 showed a fuselage that was elongated and ovoid in shape. More interestingly, it showed a canopy that could be lowered to fit flush with the top of the fuselage thereby eliminating the drag of a standard canopy. This same concept was seen in the Russian Bisnovat SK and Bartini Stal’-6, both of which were high-speed air­craft whose designers were seeking military
applications for their charges. Each wing of the T. K. 19 showed what appeared to be three weapon ports, totalling six machine guns or cannons. There were also ducts in each of the wing roots, ostensibly to cool the engine. A radiator bath may have been located in the nose of the aircraft. Given the flush canopy, the T. K.19 may have used a system similar to the Stal’-6 in which for take-off and landing the canopy hood was hinged upwards and the pilot would raise his seat. Whether the T. K.19 used a periscope vision system for the pilot once in flight as was proposed in the Soviet Lavochkin LL fighter was not known.

Like many of the other aircraft in this sec­tion, the T. K.19 would later appear in the American magazine Flight in the 25 Decem­ber 1941 issue. The description made no mention of the more striking features of the plane as described and shown in the Japan­ese magazine. Instead, the article, which con­tained no illustration, reported the T. K.19 was of orthodox appearance save that the aircraft had a twin row radial engine in the rear of the fuselage and was cooled via ducts. From this, a drawing evolved that took the basic shape of the Japanese T. K. 19 and made it more con­ventional, to the point that it bore a slight resemblance to the Curtiss P-40 Warhawk, a plane that first flew in 1938 and one that Japanese pilots first encountered in combat in late 1941. The changes from the Japanese T. K.19 included doing away with the flush canopy (providing a more standard style seen

The T. K.19 depicted here is shown in the colours of the 77th Hiko Sentai during operations in Burma, 1941-1942.

in many aircraft), moving the wings higher up the fuselage, adding pronounced wing root fairings that extended from the nose of the aircraft to rear of the cockpit (the latter being set behind the wings) and having a main landing gear reminiscent of the Brewster F2A but with landing gear doors. No weapons were shown but air intakes were illustrated in the wing roots.

From reviewing the information, US intelli­gence made the assumption that the T. K.19 was a bona fide Japanese fighter that was in service or was soon to be in service. Thus, it was codenamed Joe after Corporal Joe Grat­tan, one of the team members responsible for assigning codenames to Japanese aircraft. The T. K.19 failed to appeare in Japanese sources despite remaining in US intelligence bulletins. It eventually became clear that the T. K.19 was nothing more than a fictional air­craft and Joe was removed from future intel­ligence publications.

T. K.19-data

No information, if any, on the specifications are aoailable for the T. K. 19. Deployment

None. The T. K.19 existed only as an illustration in a magazine.

Rumpler Taube

The Imperial Flying Association purchased two Rumpler Taube aircraft prior to the out­break of World War 1. As Japan was part of the Entente Powers, and thus against Ger­many, the Japanese Army bought the two Taubes from the Association for use in action in the Tsingtao campaign. With no aircraft, the Imperial Flying Association built their own version of the Taube calling it the Isobe Kaizo Rumpler Taube. The solitary aircraft first flew in 1915 before being wrecked in a crash later in the year. The remains were cannibalised and used in the Ozaki Soga-go of 1917.

Arado Ar 196 float plane

It was reported by Allied intelligence services that the Japanese received two Arl96 float planes. However, there is no evidence to sug­gest this occurred. The Germans operated a submarine facility at Penang, Malaysia, and the unit used the Arl96 in Japanese colours which may have led to the confusion in the intelligence report.

Arado Ar 234 Blitz

jet reconnaissance bomber

The Ar234 was a twin-turbojet, single-seat reconnaissance bomber that entered service with the Luftwaffe in September 1944. Allied intelligence intercepted a communication between Germany and Japan in March 1944 that confirmed that the Japanese had data on the Ar234. It was assumed that the data related to the Ar234A, which was not as advanced as the subsequent Ar 234B models. Another report went so far as to say produc­tion plans were in place to build the latest Ar 234 aircraft but this was based solely on the fact another report stated that the FuG 136 Nachtfee visual command indicator equip­ment (used in the Ar234P series night fight­ers) had been delivered to Japan in January 1945. It would become clear that the Ar234 was never produced in Japan and it is unknown exactly what data Japan did receive on this aircraft.

Kokusai Ta-Go





Подпись: The profile depicts the Kokusai Та-Go prototype in the colours it actually sported.

In 1943, the Allied island-hopping campaign was underway and in 1944 the Japanese would see their island outposts, bases and strongholds destroyed and lost to them for­ever. In 1945, the Japanese lost their holdings in Burma, Borneo, Iwo Jima and Okinawa. Japanese military planners had no doubts that the Allies would continue their progress and land forces on the main islands of Japan. The Allies did indeed have such a plan known as Operation Downfall. The Japanese, to defend against the invasion they felt was coming, put into motion Ketsugo Sakusen or Operation Decision.

Operation Decision’s main component was the use of shimpu and shimbu missions targeting the Allied naval force, specifically landing craft, troop ships and support ships. To repel the invaders, all manner of craft were assembled for the Japanese defender of kokutai, the national polity of self sacrifice. Midget submarines such as the Kairyu, Koryu and the crude U-Kanamono, the Kaiten human torpedo, small explosive laden powerboats like the Maru-Ni (IJA) and Shinyo (UN), and even frogmen (the Fukuryu) were prepared for the final showdown. Even the best tanks, the Type 3 Chi-Nu and Type 4 Chi- To, were held in Japan to counter Allied armour. Aircraft would also play a significant role in the defence of Japan. It was estimated that 10,000 aircraft of every type would be available to throw at the Allied invasion fleet. It was thought that the mass wave tactics would result in a tremendous loss of aircraft which the Japanese industry in 1945 would be unable to keep pace with unless steps were taken to remedy such a situation. The Та-Go was one such remedy.

By 1945, Japanese industries were under regular bombardment from US airpower. In
addition to war factories being razed to the ground, Japan was being starved of materials needed to sustain weapon production. Alu­minium was a key material in aircraft pro­duction and it was estimated that by December 1945, even with strict control, the supply of this metal would be exhausted. Consequently, wood was to become the main material for aircraft construction, regardless of the type of aircraft concerned. Examples included the Tachikawa Ki-106 (a wooden version of the Nakajima Ki-84 Hay – ate) and the Kugisho D3Y Myojo (which was the wood derivative of the Aichi D3A Val). With the loss of heavy industrial machinery, it fell more and more to smaller workshops to produce components and sub-assemblies for aircraft. Often the labour force was not as skilled as before and working with wood was easier as it did not require the sophisticated tools and jigs necessary for construction of more conventional aircraft using metal com­ponents.

Captain Yoshiyuka Mizuyama, an officer in the IJA’s aviation equipment section, was the man behind the Та-Go (Та being short for take-yari, or bamboo spear). It was his desire to design and build a plane that was simple in constmction, used the bare minimum of war critical materials and could be produced rapidly. By doing so, the Та-Go could quickly populate the aircraft pool available to units destined for shimbu missions and also replenish losses in short order. He hoped that the Та-Go could be used to defend the seaside cities of Osaka and Kobe. In an effort to help realise the Та-Go, Mizuyama approached the Tachikawa Hikoki K. K. with his concept. Despite Mizuyama being an IJA officer, Tachikawa refused to assist him as his plan had no official sanction and was not

approved by the Koku Hombu. As such, Tachikawa could not spare the capacity to develop the aircraft.

Undeterred, Mizuyama discovered a small shop in the city of Tachikawa within which he and his fellow men went about the task of designing and constructing the first proto­type. Once the concept was completed, work began on building the Та-Go. Using wood lathes to construct the fuselage and other components, the aircraft was made from ply­wood while fabric was used for some of the skinning and coverings for the control sur­faces. The pilot was given a simple acrylic glass canopy. Instrumentation was kept to the bare minimum. The landing gear was fixed. For a motor, a Hitachi Ha-13 Ко 9-cylinder, air­cooled radial engine developing 450hp was selected, the cowling for it being made from plain sheet steel. The only armament was a single 500kg (1,1021b) bomb. In February 1945, the Та-Go prototype was nearly com­plete when Tachikawa was subjected to a bombing raid. In the ensuing attack, the shop was burnt to the ground and the Та-Go inside destroyed.

Despite the setback Mizuyama forged ahead, going to Nippon Kokusai Kogyo K. K. (Japan International Air Industries Co. Ltd.) to pitch his Та-Go. In the end the project was accepted and in part this may have been due to Kokusai’s experience with light aircraft such as the Ki-76 (known as Stella by the Allies) and the Ki-86 Ко (codenamed Cypress), the latter of which Kokusai had built as the prototype all-wood Ki-86 Otsu. Of course, Kokusai was not as heavily taxed by wartime demands from either the IJA or the UN and could thus allocate some assets to the development of the Та-Go. Despite Kokusai taking on the Та-Go project, it still remained an unofficial design and thus bore no Ki number.

Mizuyama’s design for Kokusai differed from the one he proposed to Tachikawa because the new version was significantly scaled down and much smaller. In so doing, this reduced the amount of assemblies needed to produce the aircraft which, by extension, lowered the man-hours required to build it. Fewer assemblies meant less use of construction materials. With the resizing, the Ha-13 radial became too large for the pro­posed airframe and so the Hitachi [Ha-47] 11 inline engine, rated at 1 lOhp, was selected as a replacement. This same engine was used in the Tokyo Koku Ki-107 all-wood two-seat trainer which was to be the replacement for the Ki-86 had the former made it into service.

In addition to the size reduction, steps were taken to simplify the Та-Go even more. Gone was the canopy and the pilot sat in a open cockpit with only a small acrylic glass wind­screen as protection from the elements. For instrumentation, only the absolute basics were used consisting of a speedometer, altimeter, compass and the essential engine related gauges such as fuel and oil. The fuse­lage was slab sided and box shaped. While this granted easier construction, it was not the most aerodynamic design. Much of the fuselage used wood sparring and structure while the skinning was of plywood. The wings were low mounted with squared wing tips and they were hinged just outside of the landing gear to enable them to fold upwards to allow the aircraft to be hidden in caves as well as facilitate their construction within the confines of caves or small manufacturing lines. Both the vertical stabiliser and the hori­zontal stabilisers were rectangular in shape.

The landing gear was fixed, being made of steel tubing and fitted with rubber wheels, each gear supported by a single strut. To pro­vide a modicum of streamlining the tubing that made up the landing gear was faired over using aluminium. The only measure of shock absorption came from the tyres and the tail skid, the latter also being built from steel tub­ing with a portion rubberised.

The [Ha-47] 11 engine was fitted with an angular plywood cowling, the engine driving a fixed-pitch, two-bladed wooden propeller. A metal engine mount was used while the fuel tank was situated on top of the engine and used a gravity feed system. Behind the tank and in front of the windscreen was a sim­ple oil cooler, mounted flush in the fuselage. Given the much smaller dimensions of the revised Та-Go, it was no longer able to carry the 500kg (1,1021b) bomb Mizuyama’s origi­nal version was designed for. Instead, it could only carry a 100kg (2201b) bomb. The bomb was fitted to the underside of the fuselage and once in place could not be released by the pilot.

Mizuyama, with the assistance of his own men and Kokusai, had completed the first prototype of the new Та-Go by the middle of June 1945 and it was made ready for flight. On 25 June, the Та-Go took to the air for the first time with a Kokusai test pilot at the controls. Not surprisingly, the pilot reported handling concerns. After a number of additional test flights, revisions were made to the design. Once complete, Kokusai created a complete set of working blueprints for the production version. However, with the cessation of hos­tilities in August 1945, the Kokusai Ta-Go never entered production. The close of the war also saw the end of two Kokusai devel­opments of the Та-Go, known as the Gi-Go and Tsu-Go. Both remain shrouded in mys­tery because no information on them has sur­faced to date.

Ironically, Tachikawa would return to the Та-Go when the Gunjusho (Ministry of Muni­tions) authorised development of Mizuyama’s initial design following the com­pletion of the Kokusai Та-Go prototype. The end of the war would find the Tachikawa Та-Go prototype incomplete. As a note, with the acceptance of the Та-Go by the Koku Hombu, a project number (meaning a Ki number) was assigned to the Та-Go – Ki-128. It has not yet been confirmed whether this Ki number applied to the Kokusai Та-Go, the Tachikawa Та-Go or both.

Та-Go – data


Messerschmitt P. l 104 Sprengstofftrager (Germany) Specifications are for the Kokusai Ta-Go.

Type Special Attack Aircraft

Crew One


One Hitachi [Ha-47] 11,4-cylinder, air-cooled inline engine developing 1 lOhp for take-off driving a wooden, two-bladed propeller 7.1ft in diameter


Span Length Height Wing area Wing loading






29.2ft 24.3ft 12.7ft 54.9ft2 7.1 lb/ft2









Max speed



Cruise speed





93 miles





One 100kg (2201b) bomb


None. A total of three Ta-Go aircraft were constructed: Mizuyama’s own prototype aircraft that was destroyed by fire prior to flight, the one built and flown at Kokusai, and the Tachikawa Ta-Go which remained incomplete at the end of the war.