Type 99 No.3 Mk.3 Sango (IJN)

Designed in 1938 and entering service in 1939, this anti-bomber bomb contained 144 white phosphorous-filled steel pellets. Its tail fins were offset to impart spin as it fell and this armed the tail fuse. The fuse would then trig­ger a burster tube down the middle of the bomb, scattering the pellets. A charge in the tail ensured the pellets were directed down­wards. Should the tail fuse fail, an impact fuse was proved in the nose of the bomb. A later modification of the bomb added fins to the body to impart a faster spin. For identification purposes the nose of the bomb was painted silver and the fins red. The bomb was.7m (2.3ft) long and weighed 34kg (741b).

Ro-Ta (IJA)

One of the problems the Japanese had with using cluster munitions was that they relied on the attacker having a higher altitude than the target in order to rain the bomblets down upon them. However, many Japanese fighters struggled at the altitudes at which the B-29s usually operated. The IJA sought to solve this dilemma with the Ro-Ta. The same Та bomblets were used but the canister was essentially a rocket that was launched towards the target. A timed fuse would trigger an explosive charge that scattered the Та bomblets. In effect, the Ro-Ta was like a buck­shot shotgun shell. Because the Ro-Ta could be fired like a rocket, there was no longer a requirement to be above the intended target in order to use the weapon. Luckily for the Allies, the Ro-Ta was still in development when the war ended.

To-2 (IJA)

Even before the To-З and Та series of cluster bombs, there was the To-2 parachute bomb. Developed in 1935, the To-2 was a 1.8m (41b) bomb that was suspended from a length of steel cable that was itself connected to a silk parachute. Ten To-2 bombs were clustered together, each cluster weighed 50kg (1101b) and the average single engine fighter could carry up to four clusters. The usual tactic was to drop the To-2 bombs into the path of oncoming bombers. To increase the depth of the bomb spread, some To-2 bombs had a smaller parachute that would result in a faster descent. The bomb was armed with an impact fuse that, regardless of where the bomb struck, would trigger the detonation. Usually the cable would be hit by the bomber with the bomb swinging up and against the plane, exploding the bomb. The To-2, how­ever, was not developed further because the cable was typically cut if hit by a wing, it relied on a high altitude to be effective and the Та munition showed far greater promise.

Japan was able to achieve where Germany failed and that was to bomb the US mainland. On 9 September 1942, the Japanese subma­rine 1-25 surfaced west of Cape Blanco, Ore­gon, and a single Kugisho E14Y1 floatplane (known as Glen to the Allies) was assembled. Pilot Warrant Officer Nobuo Fujita and observer Petty Officer Okuda Shoji climbed into the plane that was loaded with two 77kg (170 lb) incendiary bombs and took off for the US coast, heading towards the Oregon side of the Siskiyou National Forest. Once over the forest, the bombs were released in the hope a forest fire would start. However, recent rains coupled with the bombs having been dropped too low resulted in a few small fires and these quickly put out. The attack would be repeated again on 29 September 1942 but once more the results were disappointing. The first attack marked the only time in history an enemy aircraft bombed the US but another plan was in the works, one far more ambitious and ingenious, but ultimately fruitless.

The plan was called the Fu-Go, ‘Fu’ being the first kanji of the word ‘fusen’, meaning bal­loon. The ‘Go’ simply meant type. Originally conceived in 1933 by Lieutenant General Rei – kichi Toda of the Japanese Military Scientific Laboratory, the bomb dropping balloon Fu-Go was part of a series of studies into possible new weapons. Experiments with balloons capable of maintaining a stable altitude were initially allowed to proceed but by 1935 the Fu – Go project was cancelled. However, following the famous Doolittle raid on 8 April 1942, the Fu-Go was revived as a means of exacting ret­ribution for the attack.

The Fu-Go was to have been launched from submarines situated 998km (620 miles) off the US coast. In March 1943, a 6.1m (20ft) diameter balloon was successfully launched and remained aloft for at least ten hours, enough to make the submarine launch plan work. The main problem was the effect of temperature on the hydrogen gas used in the balloon. At night and in cool temperatures, the gas pressure was reduced and the balloon lost buoyancy while by day, in higher tempera­tures, there was the risk of the gas expanding and rupturing the gas envelope. Because of this launches of the balloons had to take place either by day or by night and not straddle the two times of day. However, the UN’s need for submarines to support operations in the Pacific left no room for launching the Fu-Go and the project was again cancelled in August


Remaining undeterred, the Fu-Go engi­neers looked into a solution where the bal­loon could be launched from Japan, although it would now take 50-70 hours for it to traverse the Pacific Ocean and arrive over the US mainland. General Sueyoshi Kusaba was put in command of the project to tackle the dis­tance issue and put the Fu-Go into operational use.

To overcome the problem of maintaining altitude as the balloon travelled by day and night, a ballast mechanism was designed. This consisted of a cast aluminium ring around which 32 2.5 to 3.2kg (5.5 to 7 lb) sand­bags were secured. Fuses were fitted to pairs of sandbags, the fuses powered by a small battery and connected to aneroid barometers. When the balloon sank to an altitude of around 9,144m (30,000ft), the aneroid barom­eter would trigger a switch. In turn, this trig­gered a fuse which in turn would fire two small charges that would each release a sand­bag, one across from the other to maintain balance. The balloon would then rise to an altitude of around 11,582m (38,000ft) where a gas release valve set into the bottom of the envelope discharged some of the gas to keep the balloon from rising higher. Eventually it would drop again triggering another release of sandbags followed by a rise, vent and the cycle would repeat. By the time the last pair of sandbags was dropped, it was estimated that the balloon should be over the US mainland where its destructive payload would then be released.

The balloon could lift a maximum of 136kg (3001b) at 9,144m (30,000ft). The typical munition payload was one Type 92 15kg (33 lb) high explosive bomb, one Type 100 5kg (11 lb) incendiary bomb and one Type 97 12kg (26.4 lb) incendiary bomb. A 29m (64ft) fuse was connected to a charge on the gas enve­lope and once the bombs were dropped, the fuse was lit which, in turn, destroyed the balloon.

The spherical gas envelope could store 538m3 (19,000ft3) of hydrogen gas. The diame­ter at full inflation was 10m (33ft). Early gas envelopes were constructed from rubberised silk but this was too costly to construct and the production Fu-Go used Washi paper made from the kozo bush. While Washi was inex­pensive and already produced by hand in paper mills across Japan, there was no means to ensure a constant level of quality. There­fore, the Fu-Go program had to develop mechanical methods to make Washi as well as laminate it. It took four to five layers of Washi to make a gore (a segment) and 38 to 64 gores glued together to make the sphere. The adhesive used, called konnyaku-nori, was made from konnyaku, a potato. As the glue was relatively clear, colouring was added so workers could check for evenness in the application. The glue also served as a sealant to prevent gas leakage as the untreated Washi was porous.

After being brushed with the glue, each gore was inspected for flaws. This was done by laying the gores over a panel of frosted glass beneath which was a light. The glue would appear blue and any uneven applica­tions of the glue showed up as a lighter area. All flaws were marked and patched. Once the gores had passed inspection, they were taken to the final assembly area. A large room was required with sharp objects padded so not to rip the gas envelope. High school girls were often employed for assembly, using the glue to affix the gores together to create the com­pleted gas envelope. Each girl had to ensure her nails were trimmed, that she wore gloves and socks, and that she did not wear hair pins as these could damage the gas envelope. Once the envelope was finished, it was taken to another building, often a sumo hall or the­atre (buildings specific for the task were later built), and inflated to check for leakage. After successfully passing the final inspection, the Fu-Go was completed.

The finished Fu-Go had a scalloped waist­band around the gas envelope to which the 19 shroud lines, each 14m (45ft) long, were secured. The lines were brought together and tied into two knots from which the bombs and the ballast system were hung.

With the problem of keeping a relatively sta­tic altitude solved, the next hurdle was to determine where and when to launch the bal­loons. Towards the close of 1943 and into the early part of February 1944, the Japanese launched balloons equipped with radios which were tracked so their courses could be monitored. Two stations set up in Hokkaido and in Chiba Prefecture could track the bal­loons only through the first portion of their flight, but once over the open ocean all con­tact was lost. The Japanese were aware that the west-to-east wind speeds were at their peak from November through to March, top­ping out at 298km/h (185mph). In addition, a shortage of meteorological data on weather patterns over the ocean and at high altitudes limited the ability to plan trajectories for the balloons. While the winds were higher, it was also winter throughout most of the launch window. In addition, the balloons had to be released in clear, cloudless weather with little surface wind. If balloons were sent up in over­cast skies with precipitation laden clouds, moisture would collect on the balloons which would freeze at higher altitudes, adding weight resulting in the balloons being unable to reach the US. Three major launch sites were selected: Nakoso (Fukushima Prefec­ture), Otsu (Ibaraki Prefecture) and Ichin Omiya (Chiba Prefecture).

On 3 November 1944, the Fu-Go balloon bombing campaign was officially opened. In all, between 9,000-10,000 balloons were avail­able and by 20 November, the first en masse launchings had taken place. Prior to launch, the sandbag release mechanism was set based on the estimated wind speeds to ensure the balloon was over the US before releasing its payload. The gas envelope was only partially filled to allow for expansion of the hydrogen at an altitude of 4,877m (16,000ft). On a good day crews could launch up to 200 balloons. March 1945 would see the highest number of balloons deployed, 3,000 in all, and the final launch was made on 20 April. Typically included in batches of balloon launches would be a radio equipped balloon to allow for tracking.

The first balloon was found on 4 November 1944 by a US Navy patrol boat. It had crashed into the sea 106km (66 miles) southwest of San Pedro, California. Nothing much was made of it until another turned up in the sea two weeks later. Also, balloons were found up in Montana and Wyoming and the US military realised the purpose of the balloons. Federal and state agencies were put on alert (espe­cially forest services as the threat of forest fires from the incendiaries was very real) and steps were taken to prevent news of the balloon bombs reaching the general public. This was done to prevent panic in the populace since no one could be sure when or where a bal­loon would release its bombs. In addition, by keeping the story from the press, the Japanese would be denied any information on the effectiveness of their attacks. The censorship was very effective and only one story con­cerning a balloon bomb was published appearing in Thermopolis in Wyoming. This was also reported in a Chinese newspaper. From this, the Japanese judged the Fu-Go campaign was a success and the balloon campaign continued.

The near total shutdown of public informa­tion on the balloon bombs had one severe drawback for the Americans and that was that the public had no knowledge of their exis­tence and consequently were not be warned of the dangers. The censorship would be reversed after an inevitable tragedy occurred. On 5 May 1945, near Bly, Oregon, Reverend Archie Mitchell, his wife and five children from his church group were enjoying a picnic in a wooded area. One of the children, Joan Patzke, found a balloon stuck in a tree and tried to pull it down. The subsequent explo­sion of the bombs it carried killed all but Rev­erend Mitchell. The deaths would be the only US mainland casualties from enemy action. Following the incident, the censorship was lifted to ensure public safety.

The Fourth Army Air Force was tasked with the detection and interception of the balloons. In addition, Project Firefly was initiated to position aircraft and troops to respond to for­est fires. Project Lightening was set up through the Department of Agriculture to be on alert for biological attacks against crops and livestock. Successful interception of the balloons proved difficult owing to the high alti­tudes at which they travelled, poor ground reporting and inadequate weather reporting (this would also hamper the ability of the US to accurately determine launch points from Japan). In fact, only two Fu-Gos were shot down over the US mainland. Only US Army and US Navy assets in the Aleutian Islands had a higher tally as the balloons often passed over the territory. With the problems in locating the balloons, a final plan, Project Sunset, was ini­tiated to create a web of radar sites across the coastline of Washington State. When balloons were detected, interceptors would be scram­bled to engage them. As it turned out, the plan was put into action in April 1945, the same month the Japanese ceased launching the Fu – Go. In any case, radars had a difficult time in detecting the balloons due to their low signal return.

The cost to produce one Fu-Go was approx­imately 10,000 yen. If the added expense of the design and production of the mechanical equipment to produce Washi and the erec­tion of buildings to inspect the balloons, the price of the Fu-Go project was high in com­parison to the results it brought. Still, Japanese propaganda broadcasts played up the Fu-Go prior to the project being cancelled in April 1945.

Ironically, on 10 March 1945, a balloon from one of the last launchings struck a power line, resulting in the loss of power to the nuclear plant in Hansford, Washington. This plant cre­ated the atomic material used in the Manhat­tan Project’s atomic bombs, which would ultimately be used against Japan. The loss was barely noticed as back-up systems came online to maintain the reactor. Another irony occurred on 13 March 13 when two Fu-Gos returned to Japan, although they touched down without causing any damage.

In all, 296 balloon sightings or incidents were reported across 17 US states, 5 Canadian provinces and Mexico out of the 9,000-10,000 launched. Hundreds remain unaccounted for and even today, some may still lurk in unpop­ulated areas or in dense forest presenting a danger to anyone encountering one.

Interestingly, the British would use a similar weapon against Germany. Called Operation Outward, hydrogen filled balloons equipped with a trailing steel chain to short out power lines and three 6 lb incendiary devices to trig­


Messerschmitt Bf 110 heavy fighter

Although the Japanese never imported the Bf 110, Allied sources assumed that the air­craft would be seen in combat and gave the Bf 110 the codename Doc.

Messerschmitt Me 163B Komet rocket fighter

For details, please see the chapter on the Mit­subishi J8M Syusui.

Messerschmitt Me 209 fighter

Originally, the Me 209 was designed as a high­speed aircraft capable of breaking the world air speed record. In fact, the Me 209 VI would set the record at a speed of 755.14km/h (469.22mph) on 16 April 1939. Beginning with the Me 209 V4, the design shifted to that of a fighter. Despite a number of prototypes, the Me 209 was not accepted for service. Still, Allied intelligence was positive that the Japan­ese knew of the Me 209 and, in fact, a Japan­ese military attache in Berlin did recommend in 1943 that the manufacturing rights for the aircraft be acquired as well as a sample air­craft. It would appear this was not acted upon.

Messerschmitt Me 210A-2 heavy fighter

One Me 210A-2, Werk-Nr. 2350, was modified to the standard of the Me 410 (with the excep­tion that it retained the original Daimler-Benz DB601F engines) and sent to Japan in 1942
for evaluation. After testing, no further inter­est was shown in the design.

Messerschmitt Me 262A Schwalbe jet fighter

For more details, please see the chapter on the Nakajima Kitsuka and Nakajima Ki-201 Karyu.

Messerschmitt Me 309 fighter

The Me 309 was a failed attempt to create a replacement for the Bf 109. The tricycle land­ing gear was cause for grief and in compari­son testing the Me 309 VI came up short against the ВЛ09. Fully loaded, the Me 309 offered only a marginal increase in speed over the Bf 109 and the latter could out turn the for­mer. With the advent of the Focke-Wulf Fwl90D and the superior performance it offered, the Me 309 was shelved with the remaining prototypes serving as testbeds. Despite the failure of the Me 309, the Japanese attempted to purchase the Me 309 in 1943 prior to the termination of the program. It would appear that with the cancellation of the Me 309, no sales of the remaining aircraft or manufacturing rights were offered to Japan.

Messerschmitt Me 323 Gigant transport

Allied intelligence believed that the Japanese received plans and components for the Me 323 Gigant (meaning ‘Giant’), the pow­ered version of the massive Me 321 Gigant transport glider. Although the Japanese were interested in large transports, there is no evi­dence to suggest they had an interest in the Me 323.

Messerschmitt Me 410 heavy fighter

It was thought by Allied intelligence that the Germans had shared information on the Me 410 with the Japanese in November 1942, with other sources suggesting this occurred closer to the end of 1943. However, no such interest in the Me 410 was shown nor were any aircraft delivered. It may be that some confusion was caused by the one Me 21OA-2 that Japan did receive and was configured to the Me 410 standard.

Messerschmitt Me 509 fighter

The Me 509 was a planned derivative of the Me 309, sharing components such as the tri­cycle landing gear. The Daimler-Benz DB605B 12-cylinder engine was housed inside the fuselage, behind the cockpit. The propeller was driven via an extension shaft with the cockpit situated well forwards in the nose. The wings were mounted low on the fuselage. The Kugisho R2Y1 Keiun bears an uncanny resemblance to the Me 509 and it has been suggested that when the Japanese sought the Me 309, information on the Me 509 was also provided to them. No evidence has yet proven this, however.

Kyushu J7W Shinden

In 1943, the UN issued an 18-shi specification that included the requirement for a new inter­ceptor. Japanese aircraft tasked with inter­ception roles had by this time begun to be eclipsed by the newest Allied fighters and the IJN sought to ensure their edge was main­tained. Three contenders submitted their designs and it would be Kyushu’s that was the most radical of them all: the J7W Shinden.

The man behind the Shinden (‘Magnificent Lightning’) was Captain Masaoki Tsuruno, a member of the Technical Staff of the IJN. Tsu­runo conceived an interceptor that made use of a configuration rarely seen at the time of his design work, a design with canard fore­planes. Canards were not a new concept, even in 1943. They were seen as far back as 1910 with a Gabriel and Charles Voisin design and later a Bleriot tail-first aircraft had incor­porated canards. (Both planes used the term ‘canard’ which in French means ‘duck’ – the 1910 Canard Voisin and the 1911 Bleriot ‘Canard’). Canards would sporadically appear in experimental aircraft right up to World War 2, examples being the 1929 Raab – Katzenstein Rakate, the 1931 Focke-Wulf Ente (the ‘Duck’) and the 1937 Beltrame Col – ibri. Tsuruno felt canards could offer a num­ber of advantages such as reducing the chances of stalling, improved controllability and manoeuvrability and easing some con­struction concerns such as the engine instal­lation and control linkage arrangements.

Besides the canards, Tsuruno introduced another feature in the Shinden that was cer­tainly new to the Japanese – the use of a tur­bojet to power the aircraft. Of course, Tsuruno understood that a more conven­tional piston-engine would have to be used until such time as a suitable turbojet became available, but a turbojet was incorporated into his original design to ensure that the tran­sition would not present any difficulties. At this time, the Shinden was known as the X-18.

By the time Tsuruno’s initial layout for the Shinden was complete the IJN had already issued its late 1943 18-shi specifications for three classes of aircraft. The first of these cov­ered an air superiority fighter (18-shi Ко), the second for an interceptor (18-shi Otsu) and the third for a night fighter (18-shi Hei). For the 18-shi Otsu competition, both Nakajima and Kawanishi had submitted designs: the single-engine J6K1 Jinpu (‘Squall’) and the twin-engine J5N1 Tenrai (or ‘Heavenly Thun­der’) respectively. These entries were based on the rather sparse directives of the specifi­cation which called for a top speed of 665km/h (413mph), a climb to 8,000m (26,246ft) in nine minutes and the ability to carry at least two 30mm cannons. To go with these two projects, Tsuruno introduced the Shinden to the IJN as a third competitor.

Despite some opposition to the design, the IJN was intrigued enough to accept the Shin­den proposal. However, the design had to show promise and the canard configuration needed to be proven before the IJN would authorise further development. Therefore, Tsuruno designed a glider based on his Shin­den concept as a means to test the canard properties and handling. Kugisho was com­missioned to build three gliders which were called the MXY6. Further details on MXY6 development can be found on page 69. The initial, positive results achieved with the MXY6 convinced the IJN to move forward with the Shinden project even before the completion of the glider testing by authorising two prototypes of the J7W1.

The IJN gave the Shinden project to Kyushu Нікбкі K. K. even though Kyushu had no expe­rience with high performance aircraft, let alone one like the Shinden. Unlike other major manufacturers however, Kyushu’s research facilities, personnel and production capacity were not heavily taxed by the needs of the Japanese war machine. To assist Kyushu, the IJN placed a team from the Dai – Ichi Kaigun Kokh Gijutsu-sho as well as Tsu­runo himself at the disposal of Kyushu engineers and managers to bolster their capability in handling the program.

With everything in position work com­menced on the first prototype in June 1944. The heart of the J7W1 was the Mitsubishi MK9D ([Ha-43]) 12 18-cylinder radial engine boosted by a supercharger. Although Tsuruno wanted to use a turbojet he rejected the Nel2B (TR-12) as insufficient in terms of thrust production. And since further turbojet developments were projected to show improved performance, the Shinden would use this radial engine until such time as a suit­able turbojet was available. The Mitsubishi engine and its supercharger were mounted in the rear of the fuselage. A six-bladed, metal Sumitomo VDM propeller was mated to the engine through an extension shaft and placed in a pusher configuration. If required the pro­peller could be jettisoned to effect pilot bail­out. On each side of the fuselage were air intakes for cooling the engine. The main wings were swept and on each was mounted a vertical stabiliser situated in approximately the middle of the wing. The pilot sat in a cock­pit in the centre of the fuselage while the canards were mounted on the nose. A tricy­cle landing gear was employed, the front tyre being 550x150mm and the two main tyres being 725x200mm in size.

The Shinden would carry four Type 5 30mm cannons. The Type 5, while heavier than the earlier Type 2 30mm gun, possessed a higher rate of fire at 500 rounds per minute and had a higher muzzle velocity. Each can­non was provided with 66 rounds. With less than eight seconds of 30mm rounds per gun, one hit would be sufficient to cripple and shoot down a fighter or bomber, therefore there was little ammunition to waste. There­fore, there were two Type 1 7.92mm machine guns, one on either side of the gun camera, in front of the nose. The purpose of these guns was not offensive but to serve as a ranging weapon for the cannons. Upon lining of his target, the pilot would fire a short burst from the machine guns. If the rounds struck the tar­get, he would fire a burst from the cannons and be reasonably assured of a hit, thereby conserving the precious cannon ammuni­tion. Each Type 1 was provided with 75 rounds of ammunition in a saddle dmm mag­azine. It should be noted that sources often list the two Type 1 weapons for training pur­poses, i. e. for practice and gunnery training, not gun laying. While certainly possible, gun laying would seem more plausible due to the rapid ammunition consumption of the Type 5 cannons and in training there is no real rea­son why machine guns would be used as a substitute for cannons. For payload, the Shin­den had a modest bomb carrying capacity of 120kg (2641b).

By September 1944, a model of the Shinden was being tested in a wind tunnel to assess its aerodynamic properties of the shape and planforms. With the results deemed accept­able, the first metal was cut on the prototype at the Kyushu Haruda factory located in Fukuoka City. By May 1945, the Shinden was nearly complete although it lacked the canopy, landing gear fairings, much of the main wings and other components. As the MK9D (I Ha-43 ]) 12 was already installed, test­ing of the powerplant commenced and trials showed that a cooling problem existed, prob­ably in part because no airflow was reaching the engine during static testing.

In June 1945, the first prototype was fin­ished but the armament was not fitted. Instead, weights simulating the Type 5 can­nons were installed in the nose. Flight testing was to commence immediately although the problem with the engine cooling would delay the first flight until 3 July. Tsuruno would be the first to fly the Shinden. The aircraft was to




take-off from the Mushiroda Airport in Fukuoka City. The engine was started and Tsuruno climbed into the cockpit. On releas­ing the brakes and commencing to taxi, the Shinden showed an unexpected heavy torque pulling to the right. Surprised, Tsurano was unable to stop the plane swerving off the runway where the propeller touched the ground bending several of the blades by as much as 28cm (11 inches). In addition, a por­tion of the right wing’s vertical stabiliser was also damaged. The accident would delay flight testing for nearly a month while repairs were made. To prevent the propeller from striking the ground, tail wheels, as used on the Kyushu K11W Shiragiku trainer, were fit­ted to the bottom of the vertical stabilisers.

On 3 August 1945, the Shinden was pre­pared for flight. Only 38 litres (10 gallons) of fuel were loaded with 80 litres (21 gallons) of lubricating oil. The weights simulating the


Kyushu J7W1 Shinden (FE-326)

This was the second Shinden prototype and was captured at Kyushu’s main factory. It was listed on the aviation industry release report on 10 March 1946 and to undergo restoration at MAMA by 1 August 1946. FE-326 was moved to Park Ridge in September 1946. Of note is the Shinden was provided with a stipulation that it should be housed in such a way that it could be quickly removed from storage if an engine and other parts were to be obtained to bring it to flight status. This never happened but the Shinden was fortunate enough to escape the cutting torch and was moved to the Paul. E. Garber facility where it currently remains in pieces and unrestored (see page 86).

cannons remained. The flight would be made by Kyushu’s Yoshitaka Miyaishi. With the torque now a known issue, Miyaishi was able to compensate and the Shinden successfully took to the air for the first time. The flight was for a very short duration and the aircraft was not taken above 400m (1,312ft). On landing Miyaishi reported that the take-off was rela­tively easy but rudder rise was experienced at 185km/h (115mph) with the plane lifting off the ground at 193km/h (120mph). As he climbed pushing the speed to 222km/h (138mph), the pull to the right caused by the torque from the propeller was very notice­able. After levelling off at 400m (1,312ft) and at a maximum speed of 161 mph, the pull was still a problem. He also found the landing to be a tricky process. The Shinden was found to have a relatively fast landing speed at 240km/h (149mph) and because of the torque pull and the inclination of the nose, bringing the Shinden down was not a simple task.

A second flight was made on 6 August 1945 with Miyaishi at the controls. Manoeuvrability was the main focus of the test, though the air­craft was flown up to 491 m (1,61 Oft). The pilot found that during the climb the nose wanted to dip. Again, the pull to the right was evident and during landing if a slight rudder up posi­tion was applied the nose would pop up just before touchdown. It was also discovered that the oil temperature rose as the flight went on and a means to rectify the problem would have to be found.

On 8 August 1945, the third and final flight of the Shinden took place with Miyaishi at the controls. At 193km/h (120mph), the nose wheel left the runway and at 203km/h (126mph) the plane lifted off. Miyaishi noted that the nose tended to drop regardless of how fast or slow the engine revolutions were. He also found that even with the nose down, the Shinden still flew horizontally with a level track and slight application of the rud­der. Landing speed was again 240km/h (149mph).

In total, the first Shinden logged between 30 and 45 minutes in the air. In addition to the problems already noted, Miyaishi com­plained of strong vibrations in the fuselage, in part due to the engine torque and from the extension shaft that mated the propeller to the engine. With the flight results, Kyushu engineers set about the process of solving the torque and vibration problems as well as the cooling concerns.

However, even before the Shinden took flight the IJN was desperately in need of a high performance interceptor. The Kawan – ishi J6K1 Jinpu failed to show any improve­ment over the Kawanishi N1K2-J Shiden-Kai

(meaning ‘Violet Lightning’, known to the Allies as George) and the Nakajima J5N1 Ten – rai was proving to be a disappointment by the time flight trials commenced in July 1944. With the failure of these two entries for the 18-shi specification, the IJN ordered the J7W1 Shinden into production in May 1944 and in so doing made the type the only canard configu­ration aircraft to achieve this status during World War 2. By September 1944, the pro­duction plans had been formulated with Kyushu’s Zasshonokuma factory expected to turn out 30 Shindens per month while Naka – jima’s Handa plant would produce 120 Shin­dens each month. In light of the war situation, such production numbers would have been very difficult to meet. As it was, the war ended before production could get going.

In addition to the first prototype, the second machine was also completed but it did not fly before the end of hostilities. The war’s end meant that the modifications required to cor­rect the problems found during ground and flight testing were never made. As a side note, nearly four decades later Colonel Bob Thacker would construct a radio controlled flying model of the Shinden. His initial proto­type showed the same pull problem as the original Shinden resulting in two crashes that required the complete rebuilding of the model each time. To solve this problem, Thacker placed the front canards at 7.5° pos­itive incidence, adjusted the centre of gravity and pointed the extension shaft for the pro­peller 3° to the right and 4.5° down from the zero thrust line. The pull problem was suc­cessfully eliminated by these adjustments and the Kyushu engineers may have found the same solution had they had the time to implement it.

The Shinden was not an easy aircraft to fly. Given the configuration of the aircraft, it would have required a skilled pilot to use in combat and Japan’s forces were low on experienced pilots by the time the Shinden would have entered service. The same prob­lem would plague the Germans when their high performance turbojet fighters were coming into operational use.

The end of the war also spelled the end of the J7W2 Shinden-Kai. This was to be the tur­bojet-equipped version of the Shinden. The use of the radial engine had been a stop gap until a suitable turbojet was available. The Ne 12B was rejected as its power was consid­ered too low to effectively propel the aircraft. In any case, work was by this time under way on the Kugisho Ne 20 turbojet that was based on the German BMW 003A engine, the only turbojet built and flown in a Japanese aircraft: the Nakajima Kitsuka (page 114). The J7W2 was to use the Ne 130 turbojet, also based on
the BMW 003A, which was being developed by Ishikawajima-Shibaura. The Ne 130 was to have produced nearly double the thrust of the Ne20; however, the Nel30 would not be ready by the close of the war and as such the J7W2 remained a design board aircraft. There is speculation concerning what the J7W2 would have looked like. One suggestion is that the J7W2 would have been the J7W1 with the Mitsubishi radial replaced with the Nel30 turbojet. A second suggestion con­cerns the fact that without the need for pro­

peller clearance the Shinden could dispense with the tall landing gear, thus lowering the height of the aircraft. Aside from modifying the landing gear, the vertical stabilisers, fuse­lage and canopy shape may also have required adjustment. It is likely that had development of the J7W2 commenced with the availability of the Ne 130, a J7W1 airframe would have been adapted to accept the engine and testing conducted on this, with other modifications coming into play as a pro­duction J7W2 was standardised.

Prior to the start of World War 2, there were men who foresaw the need for long range strategic bombers capable of striking across vast distances. Men like Generalleutnant Walter Wever of Germany who pushed with urgency the need for such bombers despite the veritable wall of opposition to such endeavours. This was also the case in Japan where it was clear that aggression against the United States would require the capability of hitting the US. Therefore in 1941, the Kaigun Koku Hombu issued its 16-shi specification for a long range bomber.

A review of bombers in service with the UN by 1941 showed that none were capable of crossing the Pacific to attack distant targets. At the time, the Mitsubishi G3M (codenamed Nell by the Allies) was being phased out to be replaced by the Mitsubishi G4M (known as Betty to the Allies and Hamaki or ‘Cigar’ to the Japanese). Although the G4M1 had a range of
6,043km (3,749 miles) this was insufficient to attack targets in the United States or, if required, deep into Russia. Following this review, the Kaigun Koku Hombu put forth the

16- shi specification for an attack bomber. Only two key specifications were stated. The first was that the maximum speed had to be at least 580km/h (361mph) and the second was a maximum range of at least 7,340km (4,598 miles). Mitsubishi set about the task of designing a bomber capable of meeting these requirements.

Initially, Mitsubishi engineer Kiro Honjo (who designed the G3M and G4M) proposed that the 16-shi bomber should be of a four engine design. Within Mitsubishi the bomber was known as the M-60. His pro­posal, however, was flatly rejected by the Kaigun Koku Hombu. Instead, another Mitsubishi engineer, Kijiro Takahashi, put for­ward his own design for the 16-shi bomber

which upon review was allowed to proceed.

Takahashi’s version of the M-60 was to use two ‘Nu’ engines. The Nu engine was a 24- cylinder, horizontal-H, liquid-cooled engine. Simply put, a horizontal-Н engine is two flat engines placed one on top of the other and geared together (a flat engine is one in which the pistons move horizontally). Despite hav­ing a poor power to weight ratio, they offer the advantage of being more compact and, because of this, Takahashi elected to use them on his bomber. Each engine was rated at 2,200hp at 5,000m (16,404ft).

In appearance, Takahashi’s bomber bore a strong resemblance to the Heinkel He 177 Greif (German for ‘Griffon’) heavy bomber that first flew on 19 November 1939. The nose

Mitsubishi G7M Taizan – data


Bristol Buckingham (UK), Lockheed P2V Neptune (US), Junkers Ju 88H- 1 and H-2 (Germany), Junkers Ju 288A (Germany)

The specifications for the G7MI Taizan are based on the design dimensions and estimated performance of the final G7MI proposal as derived by Mitsubishi.

Type Long-Range Bomber

Crew Seven

Powerplant Two Mitsubishi MK10A (Ha-42-11) 18-cylinder, air­cooled radial engines developing 2,000hp for take-off, l,810hp at 2,200m (7,217ft) and 1,720hp at 5,400m (17,716ft); each engine drove a metal, four-bladed, alternating stroke propeller with a 4.5m (14.7ft) diameter











Wing area


Wing loading


Power loading


8.8 lb/hp








Useful load



Bomb load


1,7641b maximum


Max speed



at 5,000m

at 26,246ft

Normal range


1,739 miles

Max range


4,598 miles


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



Fuel capacity

4,497 litres

1,188 gallons


Six 13mm Type 2 machine guns, two mounted in each of two upper fuselage turrets (one forward, one aft of the wings) and two in a ventral, rear firing position; two 20mm Type 99 Model 2 cannons, one mounted in the nose, the other in the tail

German Technical Exchange with Japan: A Brief Overview

It should not be surprising given Japan was allied to Germany as part of the Axis powers that there were numerous requests for and the exchange of war materials between the two countries. What was perhaps surprising was that the bulk of the exchange would go one way with very little going in the opposite direction.

Japan’s relationship with German aircraft and manufacturers went as far back as 1915 when the Isobe Kaizo Rumpler Taube, a copy of the Taube aircraft, was built and flown by the Imperial Flying Association. In the 1920s and 1930s, Heinkel and Junkers were the dominant German Firms, both of whose designs were much in demand by the Japanese. Other German firms such as Dornier, Rohrbach and Hansa-Brandenburg also sought to make sales prior to the start of World War 2. Before the war the Japanese military also entertained contacts with British, French and American aviation firms.

However, with the advent of hostilities and Japan having sided with the Axis powers, the country no longer had access to this broad spectrum of aviation companies and aircraft designs. Of course, through their acquisitions of aircraft prior to the war and their subse­quent study of aircraft design, the Japanese were capable of producing their own indige­nous aircraft with a good measure of success. Prior to the war beginning, and continuing through until 1943, the Japanese obtained a number of German aeroplanes. Some would see series production such as the Biicker ВІІІ31 Jungmann basic training aircraft, while others were obtained for evaluation or as comparison aircraft to be pitted against Japanese planes.

Formal agreements between Japan and Germany did exist during this time, but it was the signing of the Economic Agreement of January 1943 and, later, the Manufacturing Rights Agreement of March 1944, which paved the way for increased German techni­cal exchange. These agreements, however, restricted Japan to only acquiring technology that Germany’s war machine was fielding operationally. This clause denied Japan access to the advanced research being con­ducted by Germany’s war industry. In addi­tion, there were some in the German industrial sector and government who were reluctant to share the fruits of their labours with Japan. Nevertheless, Japan was able to obtain a considerable amount of war mater­ial for her army and navy forces. A third agree­ment, the Patent Rights Agreement drafted in December 1944, was meant to protect tech­nological advancements and prevent confis­cation of patents. The Japanese dragged their feet on the agreement and it was never signed.

It would take a decree by Reichschancellor Adolf Hitler in January 1945 to remove the restrictions of the 1943 and 1944 agreements, following which Japan had full access to the German military industry including experi­mental projects. However, by this time it was too little, too late, because both Germany and Japan lacked the capability to ship material to Japan by sea or by air.

Perhaps surprising given the very long list of technical exchanges that left Germany for Japan is that there was very little that went the other way. Germany was content to receive currency in exchange for the designs and data – Germany needed raw materials for her war industry. One of the very few examples of Japanese technology that was acquired by Germany was a single Nakajima E8N float plane (codenamed Dave by the Allies) that, oddly, ended up disguised in British markings and was used by the German merchant raider Orion. The only other occasion when Germany attempted to acquire a Japanese aircraft, the Mitsubishi Ki-46 (codenamed Dinah), the Japanese ensured that the nego­tiations with the Luftwaffe for a manufactur­ing licence went nowhere.

Japan would receive all manner of war goods and data from Germany during the war and it would make for a long list were every­thing to be included. As such, the list pre­sented here is limited to aircraft and selections pertinent to the experimental nature of the subjects in this book.

Other Exchange Items

50mm Bordkanone 5 (BK-5) aircraft cannon

This cannon, used operationally by the Ger­mans in the Me410A-l/U4 and Me410A-2/U4 heavy fighters for anti-bomber missions, gar­nered interest from the Japanese who saw the weapon at a Luftwaffe airfield in Posen in the Warthegau. There is no evidence that an example was sent to Japan.

A4 ballistic missile

Better known as the V-2, the A4 was the first ballistic missile to be used operationally in combat. In an OSS (Office of Strategic Ser­vices) report from September 1944, it was said that the Japanese had purchased the design plans for the A4. Another OSS report added that in February 1945 a Doctor Yamada of the Chemical Research Institute brought the plans to Japan. It was surmised that the Japanese were building the missile in Muk­den (Shenyang) in Northern China for use against targets in the Philippines and the Chi­nese interior. However, the OSS reports remained unverified and it was believed by other intelligence agencies that the Japanese would not have had much interest in the A4, let alone that they could construct it. Other sources say the Germans had no intention of releasing information on the A4 to the Japanese.

Blohm und Voss BV 246 Hagelkorn glider bomb

The BV 246 Hagelkorn (meaning ‘hailstone’ in German) was a radio-guided glider bomb. 1,100 examples of the BV 246 were built from December 1943 through February 1944 before the factory producing them was destroyed by bombing. Using a radio receiver, the bomb also used a smoke gener­ator to assist the operator in guiding the bomb onto the target. Despite good results, it was felt the guidance system could be too easily

jammed and production was not resumed. Allied intelligence believed that information on the BV246 was made available to the Japanese prior to April 1944.

Donau-60 Bolometer

The Danube-60 was an infra-red detection system used to control coastal guns. It used four thermal sensors in parabolic dish arrangements with a bolometer at each focal point. These dishes would detect the heat given off by ships, for example, through their funnels, and the data was then transmitted to gun layers who would bring the guns to bear on the target. Zeiss produced the system at the rate of 20-30 a month but how widespread it was in service is unknown. That the Japan­ese may have been interested in this bolome­ter can be seen in their developments of the Ке-Go (see the chapter on Japanese bombs for more information).

Fieseler Fi 103 guided bomb

Better known as the V-l or ‘buzz bomb’ (among many nicknames, German and Allied alike), the Fi 103 was a crude cruise missile first used in action against England. Intelligence reports claim that documenta­tion on the Fi 103 was provided to the Japan­ese in October 1943, and in November 1944, the Japanese acquired a Fi 103A. These reports also suggest that the Japanese were far more interested in air launching methods than ramps, and data was provided to the Japanese on the methods for air launch tech­niques as practiced by III/KG 3 and I/KG 53, who fired the Fi 103 from Heinkel He 111H-22 bombers.


None. A wooden mock-up was built before the Taizan project was cancelled.

was rounded and fully glazed, a style unlike any Japanese bomber then in service. The wings were mounted mid-fuselage, each wing sporting the Nu engine in a well-stream – lined nacelle. On top of the fuselage, fore and aft of the wings, was a turret for a portion of the defensive armament. A fairly spacious tail gunner position was fitted beneath the verti­cal stabiliser on the underside of the fuselage with a rear facing ventral gun station. A rela­tive rarity in Japanese bomber design was the tricycle landing gear. Takahashi’s perfor­mance estimates put the normal operational range at 6,412km (3,984 miles) which, with a lighter payload, could meet the 16-shi specifi­cation. The maximum speed would have been 555km/h (345mph) with a relatively light defensive weapon armament of two Type 99 20mm cannons and two Type 97 7.7mm machine guns.

Unfortunately for Takahashi, Operation Barbarossa, the German invasion of the Soviet Union on 22 June 1941, would prevent the required machine tools and equipment to produce the Nu engine from being exported to Japan. Without the powerplant, the design was doomed. With Takahashi’s proposal hav­ing fallen by the wayside, Kiro Honjo resumed control of the M-60 project. This time, instead of a four-engine bomber, Honjo would utilise two engines and base his design heavily on the G4M.

The G7M Taizan (meaning ‘Great Mountain’) as the design was later designated was to use two 18-cylinder, air-cooled radial engines, the Mitsubishi MK10A (Ha-42-11), developing 2,000hp each. The wings were mounted mid­way on the fuselage and the aircraft was to be constructed of metal with fabric covering the ailerons and rudders. It was anticipated that the Taizan would carry the same 800kg (1,7641b) bomb load as the G4M1 but unlike the Hamaki, the Taizan would have a far more potent defensive armament as the bomber would operate far from fighter protection. This step also took into account the shortcomings in the G4Ml’s protection. Of course, using less powerful engines and a heavier weapon fit caused a revision in performance when com­pared to Takahashi’s design. A 31 October 1942 performance estimate gave the G7M1 a range of 5,559km (3,454 miles) at a speed of 518km/h (322mph) at 5,000m (16,404ft) with a weapon fit of two Type 99 20mm cannons, two Type 2 13mm machine guns and two Type 1 7.9mm machine guns. However, as work on the G7M1 proceeded and the design underwent further testing, these estimates would continue to be revised. Unfortunately for Mitsubishi, the revised estimates did not see any expected improvements to the performance but rather some deterioration.

By 1942, Mitsubishi had completed the bomber’s design and were ready to construct a full size wooden mock-up of the G7M1 Taizan, which was in due course completed. Unfortunately, the Kaigun Koku Hombu had now issued a 17-shi specification for a bomber that Kawanishi was developing as the K-100 (which some sources designate as the G9K Gunzan, meaning ‘Mountain Group’, but this has never been verified; other sources have the G9K as a 1944 19-shi bomber project). Mitsubishi was instructed to halt all further work on the G7M1 until the K-100 could be evaluated.

Kawanishi completed the initial design of the K-100 bomber and the Kaigun Koku Hombu reviewed it along with the G7M1 in the summer of 1943. By this time, the G7M1 had suffered further range performance reductions, dropping from a proposed nor­mal range of 3,705km to 2,778km (2,302 miles to 1,726 miles). This was caused in part by the heavier armament compared to the initial fit, removing the two Type 1 machine guns and adding three more Type 2 machine guns to make a total of six Type 2s. This was, to a degree, tempered by a higher speed of 544km/h (344mph) at 5,000m (16,404ft).

Based on the projected performances of both aircraft, it was felt that neither design would be suitable either for the 16-shi or the

17- shi specifications. The Kaigun Koku Hombu was critical of the G7Ml’s design for concen­trating much of the defensive weaponry in the frontal arc of the bomber, thereby reducing the aircraft’s defences in the side and rear arcs. In addition, it was considered that the actual per­formance of the G7M1 would likely have been little, if at all, better than the operational G4M1. Another nail in the coffin for the G7M1 was the fact that the Kaigun Koku Hombu was looking to four-engine bombers as the real means to achieve the necessary range (at least 8,816km/5,478 miles, allowing for a one way trip from Tokyo to Los Angeles). In fact as early as 1938 the UN had asked Nakajima to produce a four-engine bomber, the G5N Shinzan (‘Mountain Recess’) which was based on an imported Douglas DC-4E.

With the Kaigun Koku Hombu showing no interest in the G7M, Mitsubishi shelved all fur­ther work on the bomber. Ironically, the G5N Shinzan would prove a failure and had a worse range than the G4M. Only with the con­struction of the four-engine Nakajima G8N1 Renzan (‘Mountain Range’) which first flew in October 1944 would the original 16-shi range specification be met. By then, the need for such bombers had passed as attention had turned to defending Japan and fighters/inter – ceptors were required.

The concept of the J4M Senden (‘Flashing Lightning’) was bom of the need for a high performance interceptor that could operate at high altitude. The main catalyst for this was the American Boeing B-17 Flying Fortress. The bomber, in action in the Pacific Theatre from 1941 to 1943, proved to be difficult to intercept since it normally flew at heights that operational Japanese fighters could not reach or attain with difficulty. Even if an interception was achieved, the B-17 carried a formidable defensive armament with which to protect itself. To a lesser extent, the Consolidated B-24 Liberator was also a factor when it began to replace the B-17s still remaining in the Pacific. In 1942, two companies, Mit­subishi and Kawanishi, were given a 17-shi Otsu specification by the Kaigun Koku Hombu to develop an aircraft to meet the need for a high altitude, high performance aircraft.

Mitsubishi Jukogyo K. K.’s response to the 17-shi Otsu directive was anything but con­
ventional when compared to Kawanishi’s design, the J3K1. The proposed plane, known within the company as the M-70, was a mono­plane pusher design that featured twin booms connected to vertical stabilisers by a low mounted horizontal stabiliser. The booms were slung under the low, fuselage mounted wings. The heart of the aircraft was to be the Mitsubishi [Ha-43] 12 MK9D tur­bocharged, radial engine. Rated at 1,650hp at 8,000m (26,246ft), it was projected that this engine would push the Senden to a top speed of 704km/h (437mph) via its six bladed pro­peller. For weapons, there was a Type 5 30mm cannon and two Type 99 20mm can­nons. All three were arranged in the fuselage nose with the Type 5 being centrally mounted and the two Type 99 cannons on either side of the fuselage. If required, the aircraft could carry a small bomb load of up to 120kg (2641b). Mounted across the top of the fuse­lage behind the cockpit were inlets to feed air to the turbocharger and engine. The purpose
of the turbocharger was to boost the manifold pressure on the engine over and above oper­ating pressures at sea level as a means to maintain and improve performance at alti­tude. For landing gear, the Senden had a tri­cycle arrangement with the nose gear retracting into the fuselage and the main wheels being housed in the booms. The pilot sat in the glazed nose of the aircraft in a cock­pit that was blended into the fuselage. The majority of the Senden was constructed of metal with fabric being used on the rudders and ailerons.

The Senden came in two versions. The first was the project described above while the second variation replaced the blended cock­pit with a bubble canopy to improve the pilot’s radius of vision. It also removed the protruding inlets and replaced them with two bands of flush inlets that wrapped around the fuselage, the first being directly behind the cockpit and the second around the engine area just past the wings. Finally, the horizon-

tal stabiliser was moved to the top of the ver­tical stabilisers. The remainder of the aircraft was basically the same between the two ver­sions. The blended cockpit version is credited as the J4M1 Project 1 while the second, with the bubble canopy and modified inlets, is sometimes referred to as the J4M4 Project 2.

After analysing the two designs, Mitsubishi selected the original configuration, the J4M1, to develop further. To confirm their initial pro­jections, a full scale model was constructed in 1943 and put to the test in a wind tunnel. Unfortunately for Mitsubishi, the tests proved to be a disappointment. Performance projec­tions based on the testing were below the ini­tial calculations and problems with the MK9D in terms of not reaching its horsepower rating only added to the concerns.

However, the Kaigun Koku Hombu and the UN ensured that Mitsubishi would not have to concern themselves further with the Senden. In 1943 as Mitsubishi was working on the Senden, the Kaigun Koku Hombu issued an

18- shi Otsu specification. From it, the Kyushu J7W Shinden resulted (page 84 for details). With the 18-shi Otsu requirements being simi­lar to the 17-shi Otsu specifications and with the J7W showing far more promise and having
the support of the UN, Mitsubishi were told to cease work on the Senden and instead further develop the Mitsubishi A7M ReppQ (‘Hurri­cane’) to meet the 17-shi Otsu standards. The result was the A7M3-J Model 34 Rifuku (Land Wind) that had not advanced beyond the design phase before the war ended.

Despite the fact that the J4M Senden did not progress past a wind tunnel model, US air intelligence was aware of the design mainly through captured documentation. In the Jan­uary 1945 issue of the US Recognition Journal, the J4M Senden was announced as a possible adversary in the coming weeks of the war. No artist renderings of the Senden were included in the article. The J4M was given the codename Luke in anticipation of Allied pilots encountering the aircraft in combat, something which was never to occur.

As a note, although there are artist impres­sions of a jet-powered Senden (as shown here) there is no evidence to support the notion the J4M was ever revived or consid­ered for turbojet power as there were other designs being considered (for example, the J7W2 and the Ki-201) which offered better prospects and capability.

In 1943, the Japanese were only too well aware of a threat looming on the horizon. That threat was the Boeing B-29 Super­fortress. With the development of the B-29 starting in 1939, the Japanese were in no doubt that once the bomber entered produc­tion it would eventually appear over Japan. The problem for the Japanese was that they did not have an effective countermeasure against the B-29 and feared they would not be able to have one ready in time for its antici­pated arrival. Fortunately, the answer was found in one of the most radical fighters ever to achieve operational status.

Towards the middle of 1943, representa­tives of the Japanese military in Berlin were notified of the development and progress of the Messerschmitt Me 163, a point defence interceptor powered by a rocket engine. Interest was expressed immediately. In short order Japanese attaches from the UN and the IJA visited Bad Zwischenahn in Germany where Erprobungskommando 16 was sta­tioned. This unit had been created earlier in 1943 to develop Me 163 combat tactics,
deployment and training as well as the coor­dination of the various contractors and test centres involved in development and pro­duction of the Me 163. During the tour EKdo 16 personnel explained to the Japanese the temperamental nature of the Walther HWK 509A rocket motor and the dangerous and explosive properties of the two fuels the motor used. This did nothing to dissuade the Japanese who saw the answer to their needs right before their eyes. To them, the benefits of an interceptor able to climb rapidly and possessing a very high speed overrode any concerns about the fuels or the engine. The Japanese wasted no time in entering negoti­ations to obtain the Me 163B.

However, not everyone was in agreement about the value of the Me 163. Detailed reports had been sent to Japan from Germany regard­ing the findings of the attaches which overall were positive; nevertheless, some argued that it would not be possible to produce the fuels the aircraft required in sufficient quantity to support operational requirements. Others criticised the unorthodox nature of the Me 163
and that developing such a plane and its engine would consume much needed resources. Despite these objections, the sup­porters for the Me 163 won out.

The Japanese swiftly and successfully negotiated the licences to manufacture both the Me 163B as well as its HWK 509A rocket motor. The motor licence alone cost the Japanese 20 million Reichsmarks. In addition to the two licences, Germany was to provide complete blueprints for the Me 163B and the HWK 509A, manufacturing data for the air­craft and engine, one complete МеІбЗВ, three HWK 509A motors, and two sets of sub – assemblies and components by no later than 1 March 1944. Also, Japanese military attaches in Berlin were to be notified of any improvements to the Me 163 design so changes could be incorporated into the Japanese version. The Japanese also requested to oversee the manufacturing processes for the Me 163B and the rocket motor as well as being allowed to study and review Luftwaffe operational procedures for the fighter. Three submarines were tasked
with shipping the materials to Japan – the RO-500, RO-501 and 1-29.

RO-500 was still named U-511 when it departed from Lorient in France on 10 May 1943 bound for Penang, Malaysia. Aboard were four Japanese including Vice Admiral Naokuni Nomura and Major Tam Otsu Sugita of the IJA medical service. Also aboard was the data for the Me 163B. During the transit, U-511 was named Satsuki 1 (‘satsuki’ mean­ing the month of May). On 16 July, U-511 reached Penang where Nomura, Sugita and the other Japanese passengers disembarked and returned to Japan by air. U-511 departed Penang for Kure, Japan, on 24 July 1943 and arrived in Kure on 7 August 1943 where the submarine was presented to the UN as the RO-500.

RO-501, a Type IXC/40 submarine, was for­mally U-1224. On 15 February 1944, U-1224 was handed over to the UN who gave it the name Satsuki 2, and on February 28, it was commissioned into the Imperial Navy as RO-501 with Lieutenant Commander Norita as captain. On 30 March 1944, RO-501 departed from Kiel, Germany, with the man­ufacturing data and blueprints for the Me 163B among other cargo. At 7.00pm on 13 May 1944, north west of the Cape Verde Islands, the USS Francis M. Robinson, a Buck – ley class destroyer escort, reported a sonar contact 755m (825 yards) from the ship. The Francis M. Robinson immediately initiated an attack, launching 24 Mark 10 Hedgehog bombs and five salvos of Mark 8 depth charges. Sonar reported four explosions sig­nifying the death of the RO-501.

1-29 of the Imperial Japanese Navy departed from Lorient, France, on 16 April 1944. She carried on board a HWK 509A rocket motor, the fuselage of a Fieseler Fi 103 and a Junkers Jumo 004A turbojet, again with other cargo. Technical Commander Eiichi Iwaya, a passenger, carried with him the plans for the МеІбЗВ and Me 262 while another passenger, Captain Matsui, had plans for accelerators used for rocket launching. Between the two of them, they also had plans for a glider bomb and radar equipment. On 14 July 1944, the 1-29 arrived safely in Singapore. Here, Iwaya and Matsui disembarked, along with a portion of their documents, and con­tinued on to Tokyo by air. On 15 July, Allied code breakers intercepted a message from Berlin to Tokyo regarding the cargo that the 1-29 carried and on 26 July 1944 at 5:00pm near the western entrance of the Balintang Channel, Luzon Strait, the USS Sawfish spot­ted the 1-29 on the surface. She fired four tor­pedoes and three struck the Japanese submarine. 1-29 sank almost immediately and only one sailor survived who swam to a nearby Philippine island and reported the loss.

Technical Commander Eiichi Iwaya, upon leaving the 1-29, did not take all of the docu­mentation he had for the Me 163B (or the Me 262) and the loss of the 1-29, along with that of the RO-501, delivered a major blow to the development program. However, the information Iwaya had preserved, combined with what was received from the RO-500, was enough to keep the project alive and in July 1944 the UN issued a 19-shi specification fora rocket powered interceptor. This decision was based on the analysis of the documenta­tion on hand for the Me 163B and the current construction capacity and capability of the air industry, and also down to the drive of Vice Admiral Misao Wada who supported the development of the rocket aircraft.

Upon issuing their 19-shi specification, the Kaigun Koku Hombu assigned the project to Mitsubishi. Mitsubishi were initially reluctant to accept the design, but further considera­tion and the need to adapt the Me 163B design to Japanese production capability saw the manufacturer agree. Even though the UN was behind the aircraft, the IJA would also be involved in the development of both the air­craft and rocket motor. The Japanese rocket interceptor was to be called the J8M1 Syusui (which means ‘Autumn Water’) and in IJA service the Syusui was to be designated Ki-200.

On 27 July 27 1944, all personnel involved met to discuss the Sytisui and it was agreed to follow the design plan of the Me 163B as much as possible. The key reason was that the design was proven and worked and thus critical time could be saved. The same applied to the rocket motor. A second reason for adhering to the Me 163B design was that Japanese fabricators had almost no experi­ence with the type of aircraft that the Me 163B was. But not everyone was in full agreement.

The IJA saw flaws in the Me 163B and felt that Japanese industry could not fully pro­duce the Syusui to the specifications of the German aircraft. Modifications to meet the current capabilities of the Japanese aviation industry would be required to both the rocket motor and the aircraft which, as a conse­quence, would force changes to the design. As such the IJA argued that in the end a new design would be required anyway. The UN, however, would hear none of it and was adamant that the Me 163B design would be followed.

Mitsubishi forged ahead with assembling a team to develop the J8M1. The project was led by Mijiro Takahashi at Mitsubishi’s Nagoya plant. Under Takahashi was Tetsuo Hikita who would be the lead designer for the air­frame. In addition to the Mitsubishi men, rep­resentatives of the Yokosuka Kokutai were involved, namely Captain Kumamoto and Commander One, who was tasked with test flying the J8M1 upon completion. Technical Commander Eiichi Iwaya was also a part of the overall development team given his famil­iarity with the МеІбЗВ acquired during his time in Germany. One last meeting was held on 7 August 1944 to finalise the development of the Syusui and then work began.

The first stage was the wooden mock-ups. On 8 September 1944, the full scale mock-up of the cockpit was completed and on 26 Sep­tember 1944, the mock-up of the Syusui was completed. Both the UN and the IJA inspected them and suggestions were made for possible alterations to the design. These changes were incorporated and Takahashi’s team laboured day and night to produce the detailed blueprints for the J8M1. Three proto­types were to be built; the first would be for load testing while the remaining two would be used for the flight test program. As the rocket motor was not yet available, two of the prototypes would be weighted to simulate the motor and fuel. To hasten construction, when one portion of the aircraft was drafted and Finalised, a copy was sent to the assem­bly shop assigned to construct the compo­nent so work could begin without delay.

Externally, the J8M1 was unmistakable in its lineage but Takahashi and his group had to make modifications as they adapted the МеІбЗВ design. For example, the МеІбЗВ used two MK 108 30mm cannons which were heavier and shorter than the 30mm cannons the Japanese were to use. Fuel capacity was similar to the German aircraft and so were the dimensions, although the J8M1 was slightly longer due its more pointed nose and had a wider span and smaller wing area. (The Syusui unlike the Me 163B did not use a nose – installed generator, the space being used for radio equipment.) The wing thickness was also increased. The main difference, how­ever, was the weight: the Sytisui was 363 to 408kg (800-900lb) lighter than the МеІбЗВ. This was not due to any effort to purposely lighten the Sytisui as it lacked armour protec­tion for the pilot and carried less ammunition for its cannons than the German interceptor. For weapons, the J8M1 was to be equipped with two Type 5 30mm cannons in the wings while the IJA’s Ki-200 would use two Ho-155 30mm cannons or two Ho-5 20mm cannons.

Because the Japanese lacked the experi­ence in flying tailless aircraft, Kugisho was tasked with creating a glider version of the Syusui. In part, the glider would provide per­formance data, findings from which could be incorporated into the Syusui, but would also serve as a trainer for rocket aircraft pilots. Therefore, the MXY8 Akigusa and MXY9 Shuka were developed, as described else­where in this book on page 77.

While work was underway on the first three prototypes, a production plan for the fighter was put together and was completed by October 1944. By March 1945, 155 SyQsui were to be produced with another 1,145 built by September 1945. Ultimately, by March 1946 at least 3,600 SyQsui were anticipated to be in service.

In addition to developing the Syusui, Mit­subishi was also assigned the task of creating the Japanese version of the Walther HWK 509A rocket motor and both the UN and the IJA were involved in the motor program. To assist the engineers in Mitsubishi’s engine department, personnel from the IJA’s First Army Air Arsenal engine section were assigned to the firm. The resulting motor was called the KR10 but was also known as the Toku-Ro.2. Components for the KR10 were constructed by four companies: Hitachi, Ishikawajima, Mitsubishi and Washimo. Washimo, for example, was responsible for the fuel flow control mechanisms and the relief valve for the Ко fuel tank.

Mitsubishi faced several problems in build­ing the KR10, the main issue being that the HWK 509A used a nickel-chromium alloy in the fuel injector atomiser, regulating valves and relief valves. Since the Japanese did not have access to this alloy they had to use plain chromium steel. It was expected that the KR10 would be ready for testing by October 1944, but the first prototype exploded imme­diately when it was started for the first time, partly believed to have been caused by the metal used. A deviation was made from the original HWK 509A plan in that the KR10 motor used wider supports and included a bearing in the middle for the Ко fuel com­pressor. This revision in the KR10 resulted in the KR12 but the addition of a second version of the motor risked compounding any pro­duction problems. Indeed, testing of the KR12 also resulted in an explosion. Mitsubishi engi­neers discovered that a bearing seal had failed that allowed the Ко fuel to leak into the motor and then come into contact with the bearing lubricant with catastrophic results. Given that it offered no real advantage, the KR12 was shelved and work focused solely on the KR10. These accidents, their subse­quent investigations and the resulting revi­sions put the KR10’s development further and further behind.

For fuel, the Syusui used two ingredients which, when combined, provided the com­bustion and resultant thrust. The First, Ко, was the Japanese version of the German fuel

T-Stoff formed from eighty per cent hydrogen peroxide with the remainder Oxyquinoline and pyrophosphates to act as stabilisers. Ко was the oxidising fuel. The second, Otsu, was the Japanese equivalent of C-Stoff. Otsu was the reductant fuel and was composed of thirty per cent hydrazine hydrate with the remainder being methanol, water and potas­sium-copper cyanides. Together, Ко and Otsu were a hypergolic fuel combination, which meant that when the two fuels were combined they spontaneously ignited. The problem with Ко and Otsu was that they were colourless and, of course, when they came together, the result was explosive. This required strict handling procedures and con­tainment methods. Both fuels were stored in special ceramic pots. To produce both fuels, three chemical companies were contracted. They were the UN’s First Fuel Arsenal, Mit­subishi Kasei and Edogawa Kagaku. In the Syusui, the fuels were stored in wing and fuselage mounted tanks. The pilot sat between two 91 litres (24 gallons) tanks of Ко while behind him in the fuselage was a 961 litres (254 gallons) tank and a 8 litre (2 gallon) tank of Ко. Each wing housed two tanks of Otsu, the capacity of each tank in each wing being 64 and 197 litres (17 and 52 gallons) in the two tanks respectively.

By December 1944, the second and third J8M1 s had been completed but as no engines were ready for installation, ballast was used to simulate the weight of the KR10 with full fuel tanks. Earlier, the first J8M1 had been completed and load tested on 1 December 1944. However, the 7.9 magnitude Tonankai earthquake that struck the Tokai region of Japan at 1.30pm on 7 December 1944 destroyed the aircraft and the testing facility that housed it. The remaining J8M1 aircraft were transferred to the UN’s First Naval Air Technical Arsenal. From there, the aircraft were shipped to Hyakurigahara, located about 79km (49 miles) northeast of Tokyo. December would also see delays due to the increasing B-29 bomber raids. Attacks against Mitsubishi’s Nagoya facility resulted in the KR10 program being moved to the Dai-Juichi Kaigun Kokusho complex at the Hiro Naval Arsenal in Kure, Hiroshima. Here, work con­tinued on the motor supervised by Professor Kasai of the Kyushu University (although another source states the entire engine devel­opment group was moved to an underground facility in Natsushima in Yokosuka prefec­ture, overseen by the Dai-Juichi Kaigun Kokusho).

During testing, the KR10 delivered less thrust than the HWK 509A. Although the SyQsui was lighter than the Me 163B, when Takahashi and Hikita completed perfor­mance calculations for the SyQsui based on the thrust rating of the KR10, they found that the lighter weight did not totally offset the lower thrust. Regardless, the estimated speed and climb rate was considered exceptional.

On 8 January 1945, a Nakajima B6N1 (known as Jill to the Allies) towed the SyQsui into the air from the Hyakurigahara airfield and after a successful flight the design was vali­dated. Work quickly proceeded on further production of the SyQsui, this time with the KR10. However, the motor program was at least three months behind schedule and it was not until 11 April 1945 that the KR10 was suffi­ciently developed to enable it to function with some measure of reliability. With the possibil­ity of powered flight, Captain Shibata, com­mander of the 312 KokQtai due to be equipped with the J8M1, sought to speed up the process for testing. In discussions with the SyQsui development team it was decided that if the KR10 could produce thrust for at least two minutes without mishap, the motor should be Fitted to the SyQsui so that powered flight test­ing could commence. 22 April 1945 was set as the deadline for the first powered flight.

Meanwhile, Germany made another attempt to send more material to Japan including documents and parts for the Me 163. These items and other cargo were loaded onboard U-864 that departed from the Bruno U-boat pen located in Bergen, Norway, on 5 February 1945. However, having past Fedje the submarine developed a misfire in one of her two MAN diesel engines and it was necessary to return to Bergen to effect repairs. The British submarine HMS Venturer, dispatched to deal with U-864, spotted the German submarine’s periscope on 9 Febru­ary 1945. Korvettenkapitan Ralf-Reimar Wol­fram realised he was being followed and began to take evasive action, moving in a zig­zag fashion. James S. Launders, Venturer’s captain, decided to press home the attack and fired all four of his loaded torpedoes in a spread pattern. U-864 crash dived, dodged three of the torpedoes but turned into the fourth which struck the submarine. The resulting explosion split U-864 into two.

Unfortunately for the SyQsui, the deadline for the KR 10 would not be met. In exhaustive testing, another motor detonated after having achieved two minutes of burn time. In addi­tion, fears of B-29 raids saw the KR10 team being moved to the Yamakita factory com­plex in Hakome prefecture while the Mit­subishi SyQsui development group was relocated to the IJA research and develop­ment centre in Matsumoto in Nagano Prefec­ture. These moves consumed precious research time throughout April and May 1945. Both groups were eventually able to continue

work on the KR10 in an attempt to enhance its reliability and, in June, success was achieved. A KR10 from the Yamakita group functioned for four minutes while the Mit­subishi group in Matsumoto managed three minutes. With these motors now meeting the

two minute requirement, plans were swiftly prepared to install the Yamakita KR10 into a J8M1 while the Matsumoto motor was to be placed into another airframe that would be completed as a Ki-200.

The J8Ml’s installation was completed first

in the second week of June 1945 at Mit­subishi’s Number One Plant in Nagoya. The Syusui lacked much of its operational equip­ment including weapons and was trans­ported to Yokoku airfield. This site was favoured because it was situated along a shoreline, which meant that if the pilot had to ditch the aircraft he could do so into the ocean, offering a better chance for survival as well as possibly lessening the damage to the Syusui. The Syusui arrived at Yokoku at the beginning of July and ground testing began immediately. Secured to the tarmac, the tail of the Syusui was removed exposing the KR10 and motor running tests commenced. It was found that the motor did not burn fuel evenly, generating plumes of light red smoke from the combustion chamber as it ran. By 5 July 1945, technicians and engineers had cor­rected the burn problem to the point that the KR10 was deemed ready and the Syusui’s first powered flight was scheduled for 7 July 1945.

In front of a crowd of onlookers, the Syusui was moved to the start of the 1,200m (3,937ft) runway, the longer of the two at Yokoku. It was then fuelled with 568 litres (150 gallons) of Ко into the fuselage tanks and 159 litres (42 gallons) of Otsu into the wing tanks as the mixture ratio was approximately 10 to 3.6. At 4:55pm, the pilot, Lieutenant-Commander Toyohiko Inuzuka, fired the engine and within 11 seconds and after only 320m (1,049ft) of runway, the Syusui lifted off the ground and into the air, Inuzuka releasing the dolly and raising the nose to provide a 45° angle climb. Then, at 350m (1,148ft), a puff of black smoke issued from the motor, sput­tered and went out. The speed that had been built up carried the Syusui up to 500m (1,640ft) where Inuzuka levelled off and banked to the right ready to return to the run­way and land. As Inuzuka continued his right hand bank, the Syusui began to drift and air­speed rapidly dropped off. As he approached the runway, Inuzuka raised the nose of the Syusui to try and avoid colliding with a build­ing but it was too late. A wing clipped the side of the building, putting the Syusui into a crash so forceful that it broke apart, scattering pieces across the south-west edge of the air­field. Both wings were ripped away and the front of the aircraft was completely destroyed. Inuzuka survived the impact and was extracted from the wreckage. However, the extent of his injuries was so severe that he died the following day.

No time was wasted in trying to find the cause of the motor failure. Mechanical issues were ruled out and it was surmised that the puff of smoke and the subsequent loss of power from the KR10 was due to fuel being cut off from the motor. Miraculously, the fuel

tanks did not explode on impact and it was found that at least half of the fuel loaded prior to take-off remained. It was determined that the culprit was the fuel line from the Ко tank. Due to poor design, when the Sytisui went into its climb the fuel in the tank shifted away from the line which starved the motor of the needed oxidiser and thus the KR10 cut out. While the investigation was being carried out, bench tests of two additional KR10 motors (one each at Matsumoto and Yamakita) resulted in both exploding. This left a single KR10, the one slated for the Ki-200.

Flight testing of the Sytisui was suspended until the problem with the fuel system could be resolved. A further four Sytisui aircraft had been completed by Mitsubishi by the time a solution was found. These changes were incorporated into the KR10 engines then under development and flight testing was scheduled to resume in late August 1945. However, on 15 August 1945, Japan surren­dered. All further work on the Sytisui ceased and no further flights were made. At the end of the war the Ki-200 remained engineless, its KR10 never having been installed. Aside from the seven J8M1 aircraft built – including the one to be finished as the Ki-200 – another six were in various stages of completion. A fur­ther four KR10 motors had been completed with another two nearly finished. Enough components had been constructed to assem­ble a further twenty motors.

Another variant of the J8M had been planned which was called the J8M2 Syusui – Kai. The J8M2 lost one of the Type 5 30mm cannons/ammunition to be replaced by addi­tional fuel tankage. It was hoped that this would increase the endurance of the aircraft. The end of hostilities would see the J8M2 remain only a preliminary design though pro­duction of the J8M2 was a certainty had it been completed. As mentioned earlier, the IJA was not pleased with the Ki-200 and it would undertake development of its own ver­sion of the J8M, the Ki-202 Syusui-Kai, to right the wrongs it felt were evident in the Sytisui. For more details, please see the chapter on the Ki-202 (page 40).

A note regarding the use of Sytisui as the name for the J8M. The kanji for the aircraft (SyO and Sui) translate as ‘Autumn Water’. However, Shtisui has been used in many sources with translations ranging from ‘Sword Stroke’ or ‘Swinging Sword’ to ‘Rigor­ous Sword’, but the name Shtisui is not cor­rect. The use of Shiisui evolved from the metaphor that Sytisui represents – the wavy pattern on the metal blade of a highly sharp­ened sword as well as the brightness of the polished metal which reminds one of the waves on a body of clear water.


Messerschmitt Me 163B Komet (Germany)

Specifications in parenthesis pertain to the J8M2 only and are based on Mitsubishi’s estimated data.

Type Interceptor/Fighter

Crew One


One Toku-Ro.2 (KR10) bi-fuel rocket motor developing 1,500kg (3,307 lb) of thrust


Span Length Height Wing area Wing loading








31.1ft 19.8ft 8.8ft 190.8ft2 44.9 lb/ft2 45 lb/fl2




















Useful load







Max speed

900km/h at 10,000m

559mph at 32,810ft

Cruise speed



Landing speed




3 min 6 sec of powered flight at 599km/h 372mph

Max range

5 min 30 sec of powered flight


40 sec to 2,000m (6,561ft)

2 min 8 sec to 4,000m (13,123ft)

3 min 8 sec to 8,000m (26,246ft)

3 min 50 sec to 10,000m (32,808ft)

Ceiling 12,000m 39,370ft

Fuel capacity 1,181 litres (312 gallons) of Ко and

522 litres (138 gallons) of Otsu


Two Type 5 30mm cannons with 53 rounds of ammunition per gun (one Type 5 cannon with 53 rounds of ammunition)


None. A total of seven J8M1 aircraft were completed with one to be finished as a Ki-200. The 312 Kokutai were to receive the J8M1 had it entered production. No J8M2 was ever built nor were any Ki-200 aircraft.


Mitsubishi J8M1 Sytisui (FE-300)

One of three brought from Yokosuka on 3 November 1945, this Sytisui is aircraft No.403 and is thought to have been captured at Mitsubishi’s No. l plant in Nagoya. Appearing on the 10 March 1946 report for aircraft releasable to the aviation industry, the Sytisui would be made available for display purposes on 1 August 1946 appearing to the public in Hollywood, California. The aircraft was later obtained and restored by Edward Maloney for display at the Planes of Fame Museum in Chino, California, where it remains to this day.

Mitsubishi J8M1 Sytisui (tail number 24)

After being received at NAS Patuxent River, the aircraft was moved to NAS Glenview in Glenview, Illinois (a suburb of Chicago, Illinois), where it was on display by 3 October 1946. This Sytisui eventually reached a derelict state and was scrapped.

Mitsubishi J8M1 Sytisui (tail number A-25)

Nothing is known about this particular Sytisui other than it likely ended up as scrap.

Mitsubishi J8M1 Sytisui

Mitsubishi has recently restored a J8M1 and it is currently on display at the company’s Komaki Plant Museum. A portion of the restoration contains components from a badly damaged J8M1 fuselage found in a cave but it still required significant custom fabrication of new parts to finish the project. Prior to Mitsubishi obtaining the fuselage, the remains had been on display on the grounds of the Japanese Air Self-Defence Force’s Gifu Air Base.

Ki-200 – data (estimated)






One Toku-Ro.2 (KR10) bi-fuel rocket motor

developing 1,500kg (3,3071b) of thrust











Wing area











Max speed



at 10,000m

at 32,808ft

Cruise speed

351 km/h



2 min 30 sec of powered flight

Max range

7 min of powered flight


3 min 40 sec to 10,000m (32,808ft)

Fuel capacity

1,181 litres (312 gallons) of Ко

and 522 litres (138 gallons) of Otsu


Two Ho-155 30mm cannons (or two Ho-5 20mm cannons)

Dornier Do C transport

In 1927, Kawasaki imported seven aircraft from Dornier including the Do C Komet. Although rejected by the Japanese military, Kawasaki used the Komet to fill an order for three passenger transports from the newspa­per service Asahi Shimbun Sha. The three air­craft, known as the Kawasaki-Dornier Komet, were built from imported components. Kawasaki later imported a Dornier Merkur, an updated Komet, leasing the aircraft as the Kawasaki-Dornier Merkur to Asahi Shimbun. However, this Merkur would instead see ser­vice with the Army as the Aikoku No. 2 after its conversion to an ambulance. Used during the Manchurian Incident, the Aikoku No. 2 was very active in casualty evacuation and upon retirement became a monument. When the Russians invaded Manchuria in 1945, the plane was burned by the retreating Japanese troops.

Dornier Do J Wal flying boat

In 1929, Kawasaki received an order for a pas­senger flying boat. As they already had an imported Dornier Wal flying boat from which to source a design, Kawasaki essentially pro­duced their own version using imported com­ponents from Dornier. A total of three were built by 1930, being flown as liners for regular passenger services.

Dornier Do N heavy bomber

In 1924, the Army asked Kawasaki to produce a bomber to replace types already in service. To this end, Kawasaki enlisted Dornier and BMW as collaborators on what would become the Type 87 Heavy Bomber. Dornier designed the Do N and the plane was built by Kawasaki, the first completed in 1927. After a year of test­ing, the bomber, now called the Type 87, was accepted into army service, the last of the 28 bombers being delivered in 1932. Kawasaki produced the BMW VI for the Type 87 under licence. Equipping a handful of bomber chutai, the Type 87 would see brief action dur­ing the Manchurian Incident of 1931.

Heinkel HeS 011 turbojet

The HeS was to be the next generation of tur­bojet and was to be the powerplant of choice for a great number of German project designs, and also the first of the second gen­eration jet fighters such as the Messerschmitt P 1101 and the Focke-Wulf Та 183 ‘Hucke – bein’. Only 19 were built before the close of the war and the engine never attained pro­duction status. Allied intelligence cited a 12 March 1945 letter from Kurt Fammertz to Director Wolff of Heinkel-Hirth stating that the 1JN should be supplied with complete plans for the HeS 011 engine and that it should be transferred via submarine. There is no evi­dence to show this transfer was completed.

Henschel Hs293 guided bomb

The Hs 293 was an SC500 bomb onto which wings, a tail and a rocket engine were mated. The Hs293A-l, which was the only opera­tional model, used radio signals to direct its bomb to the target. Later test versions used
wire-guidance as a means to defeat jamming. The weapon entered service in 1943 and, early in that year, a Japanese delegation was given a demonstration of the Hs293A-l at a field in Gartz in Germany. The Germans kept information on the improved, wire-guided Hs 293A-2 from the delegation. It is unknown if the Japanese acquired further information on the weapon and Allied intelligence reports suggest that, if they had, the Hs 293 would not have reached service until the fall of 1945. In addition, one report makes the assumption that the Hs293 was an influence on the Kugisho MXY7 Oka in so far as a human oper­ator, in the weapon itself, would have over­come the lengthy research and development of a radio guided munitions.

Henschel Hs 294 guided bomb

This was an improved version of the He 293, incorporating a longer, more pointed nose, heavier warhead and two rocket engines. The Hs294A used radio guidance, the Hs 294B wire guidance and the Hs 294D used television guidance. The Hs294 failed to see service. However, in December 1944, UN rep­resentatives met with German Air Ministry officials to discuss the Hs 294 but with what results is unknown.

Rheinmetall-Borsig MK 108 30mm aircraft cannon

Known as the ‘pneumatic hammer’, the MK 108 cannon was a very successful weapon encompassing heavy hitting power, ease of manufacturing and compactness in one package. Despite having a low muzzle veloc­ity which reduced range, it was used on a number of operational German aircraft and secret projects. The Japanese were very interested in manufacturing the cannon and studied the requirements to produce it. Cap­tured documentation in June 1943 suggested production was soon to be underway as the Japanese had received examples of the MK 108A-2 cannon. The MK 108 was not built in Japan.

Ruhrstahl-Kramer PC 1400X Fritz-X guided bomb

The Fritz-X was a guided munition made from the unguided PC 1400 ‘Fritz’ bomb. Using a cruciform tail arrangement with guidable fins, the Fritz-X was directed to the target via radio signals sent by the operator in the launch aircraft. To help visibility, flares were installed in the tail. The munition saw service from August 1943 to the end of the war in April 1945, being relatively successful in the anti­shipping role. The Japanese were aware of the Fritz-X and information on the bomb was available to Japan in September 1944. It is unknown if any examples were provided or if the Japanese pursued the weapon further.


If you browse any major book seller, you tend to see a good many works on the experimen­tal aircraft developed by Germany both before and, particularly, during World War 2. Also, you’d find a fine selection of books on the topic of American experimental planes. From time to time, you could find mention of such ‘X-planes’ of other nations amongst the text describing more well known aircraft. But you did not often see, if at all, books dedi­cated to Japanese experimental aircraft. Usu­ally, one had to visit specialty book dealers, hobby shops, or be fortunate enough to be able to read another language in order to find books on the subject of Japanese X-planes.

I was first exposed to the world of Japanese experimental aircraft in 1988 through the classic book Japanese Aircraft of the Pacific War by Rene J. Francillon. I found the book on the shelf in your typical mall bookstore. Sure, before then, I knew about the classic Japanese planes such as the Mitsubishi A6M Reisen and the Nakajima Ki-43 Hayabusa. But Francillon’s book brought to me such planes as the Nakajima Kitsuka, Mitsubishi J8M Syusui and the Tachikawa Ki-94.

My interest in military technology sat on the kerb through my college years but afterwards it slowly ramped back up. I found that I focused my reading on the military machine of Germany and the sheer breadth of techno­logical innovation their engineers and scien­tists churned out. Small arms, armour, artillery, missiles, submarines, aircraft, rock­etry and much more – no stone was left unturned by Germany’s scientists. It was dur­ing my studies of German aviation that I would see the Japanese pop up from time to time. Most often, it was the acquisition of Ger­man technology for development in Japan, or German plane designs offered for the Japan­ese to purchase. This piqued my interest in learning about what the Japanese had brew­ing in their aviation cauldron.

By this time, the World Wide Web was becoming the engine of information that it is today. While I was able to find bits of infor­mation regarding Japanese X-planes, it was never anything substantive. Stops into the local hobby shop or major book retailers did not turn up anything above and beyond what I already knew. I found a rather large gap in the online data pool on Japanese X-planes, at least in English, and so I sought about cor­recting that.

In 1998, I began to assemble a website inspired by Dan Johnson’s Luft ’46 which started in 1997 as a one-stop site about Ger­man X-planes. In 1999, my site, Hikoki: 1946, went live to the world. During its first few years, Hikoki: 1946 expanded to encompass 31 Japanese experimental aircraft and sec­tions on engine specifications, German air­craft the Japanese were interested in or bought, missiles and more. Support for the site was great. Such people as artist Ted Nomura, Polish author Tadeusz Januszewski and J-Air – craft. com contributors Mike Goodwin, George Elephtheriou and D. Karacay helped the site by providing both artwork and data on some of the planes presented. By 2002, I felt that I’d exhausted what there was on the subject and the site entered a state of finality with no fur­ther updates having been done since.

Fast forward to the fall of 2007. Jay Slater of Ian Allan Publishing e-mailed me to discuss the prospect of writing a book on Japanese experimental aircraft. This was not the first time someone had approached me to do so. But unlike the others, Jay had a well known publisher behind him who had a number of X-plane books in print, many of which 1 had in my own library. It seemed natural to him that a book on Japanese X-planes would be a wel­come complement to their existing titles as well as providing the English aviation histo­rian or enthusiast with a ready source of ded­icated information on Japanese X-planes. I certainly agreed.

The work you hold is not simply my Hikoki: 1946 website in book form. Yes, some of the aircraft in these pages can be found on the site but the information here has been further researched and revised. This means the data in these pages is far more up to date than the site. And for sure, the outstanding artwork provided makes this a spectacular publica­tion and investment for your library.

Because of the constraints on the number of pages, there had to be a process of select­ing aircraft for inclusion. The planes selected for this volume have been chosen based on several factors. The first was the nature of the plane in terms of being a conventional or a more radical design. Thus, while the Kugisho D3Y Myojo may be a relatively obscure plane of which only two were built, it was a very conventional aircraft in terms of design. The same applied to the Mitsubishi Ki-83. There­fore, these more conventional designs or pro­totypes received a lower selection priority over more advanced concepts. Another fac­tor concerned aircraft which were derivatives of established production planes in the Japanese arsenal. As such, designs such as the Ki-116, which was derived from the Naka­jima Ki-84 Hayate, are also excluded. A third factor revolved around the pool of informa­tion available for a certain design. The more obscure or unknown the design was, the higher it was considered over other planes. For example, the scope of the Rikugun Kogiken designs were of far more interest and of a lesser known nature than the proto­types of the Nakajima G8N Renzan or the Aichi SI A Denko of which more information is readily available. Finally, X-planes that were purely research aircraft such as the Kawasaki Ki-78, those experimental planes constructed prior to the start of the war, and most of the non-combat aircraft (transports, gliders and the like) were generally excluded from contention. Perhaps in a future publica­tion, those designs that did not make the cut for this book will get their chance.

It may appear that few aircraft remained with such pruning but it still left a significant number of planes to choose from, from the historically important Nakajima Kitsuka and Mitsubishi J8M Syusui, to more unknown types such as the Kugisho Tenga and Kawan – ishi K-200.

In so far as the book layout, aircraft are sep­arated by service (IJA and UN) and then alphabetised by manufacturer. Those aircraft that were not of either service (or were joint projects) are listed last. Missiles and a selec­tion of some of the more interesting aircraft munitions that were deployed or were in development are included along with a brief discourse on German technical exchange with Japan before and during World War 2. A feature in each aircraft chapter is the inclu­sion of a ‘Contemporaries’ section. The pur­pose of this is to illustrate to the reader that designs didn’t occur in a vacuum and similar concepts could be found in other Allied nations as well as Axis ones. This section should not in any way be construed as point­ing to the Japanese as simply copying the work of other nations. While it is true that the Japanese air forces prior to the war were very keen on obtaining as much information on aviation technology as possible (and, in some cases, built and flew versions of foreign air­craft), once hostilities began Japan knew she could no longer rely on outside assistance for their aircraft industry and ensured it could stand on its own. This it did, producing many successful aircraft that were indigenous. The influx of German technology during the war can be viewed as another means by which Japanese aviation technology was boosted through a wartime ally, but more often than not it was an expediency to rapidly increase the capability of Japanese aircraft in the face of a worsening war situation and ever improv­ing Allied fighters and bombers. It is hoped the information in this section will be a cata­lyst to learn more about the aircraft presented to expand one’s knowledge of aviation by other nations. Also keep in mind that this sec­tion does not list each and every plane that could be considered a contemporary. Instead, I have picked the more interesting and have intentionally listed only the aircraft name(s) in order to not take away from the main topic at hand. The reader will also find with certain aircraft a section called ‘Sur­vivors’. Listed here are those aircraft that sur­vived the war and what their fates were, either being scrapped or escaping the cutting torch. Where known, the Hepburn Romani – sation system is utilised for Japanese words.

Every attempt has been made to ensure

accuracy in the information provided in this book. Even as the writing of the book was underway, I was acquiring additional sources and checking and rechecking data to make sure nothing was amiss. Of course, at some point I had to ‘let it go’. If I held on to chapters waiting on the next titbit of information to appear, the book would never get finished and you wouldn’t be holding it in your hands. Thus, invariably, there is the risk of omitting something, interpreting a translation or source incorrectly, or just plain making an error. To that end, corrections, new informa­tion and any and all comments can be directed to the author at the e-mail address below.

I hope you, the reader, enjoy the book and find it a worthwhile addition to your library as a ready resource on some of the most inter­esting Japanese airplanes of the war.


Edwin M. Dyer III

japanesesecretprojects@gmail. com

Mitsubishi-Payen Pa.400 and Suzukaze 20

When Allied intelligence discovered an illus­tration of the Suzukaze 20 in a Japanese mag­azine, it was unlike anything so far seen in Japanese aviation design. Despite the radical appearance, it was felt the Suzukaze 20 was a bona fide aircraft and might be encountered in action. As it was, the plane was a work of fiction and so the Suzukaze 20 was later stricken from the publications on Japanese aircraft identification and coding. However, Allied intelligence may or may not have been aware of the very real inspiration for the artist of the Suzukaze 20.

At the time, because of the relative difficulty in obtaining information on Japanese military matters, intelligence services relied on vari­ous publications such as newspapers and magazines as a means to glean data on the Japanese military machine. In April 1941, the Japanese magazine Sora (translated as ‘Sky’) published a number of illustrations of various aircraft in a section entitled ‘Dreams of Future Designers’. Included in the selection of art­work was the rendition of the Suzukaze (‘Cool Breeze’) 20. The 25 December 1941 issue of the US magazine Flight would also feature the Suzukaze 20, along with three other aircraft: the Nakajima AT27 (codenamed Gus), the Mitsubishi T. K.4 Type 0 (codenamed Frank then Harry) and the T. K.19 (codenamed Joe). The Suzukaze 20 would receive the code – name Omar.

The illustration of the Suzukaze 20 depicted a single-seat fighter with the striking feature of having a cockpit blended into the vertical sta­biliser that was itself in the form of a half-delta. Another notable feature was the use of two radial engines, one mounted behind the other, driving two, contra-rotating propellers. Armament appeared to be heavy with four weapons fitted in each wing. Its speed was given as 769km/h (478mph), loaded weight 2,858kg (6,3001b), wing area 13.37m2 (144ft2) and wing loading 214.82kg/m2 (44 lb/ft2).

As the war dragged on it became evident that the Suzukaze 20, along with the other three aircraft illustrated with it, were works of fantasy and thus all four were removed from Japanese aircraft intelligence bulletins, the last of them disappearing by June 1943. Despite the Suzukaze 20 being a fictional air­craft, there was a kerne! of truth behind it that perhaps germinated in the mind of the artist that drew the Suzukaze 20. The kernel could have been the works of the French aircraft designer, Nicholas Roland Payen.

Payen was born in France in 1914 and became interested in aviation early in life. By the 1930s, he had begun to focus on the use of delta planforms as well as canards and ogival (bullet shaped) flight surfaces. Throughout his life, Payen would design a large number of air­craft in a wide array of configurations but, despite the prolific nature of his studies, only two were built before the end of World War 2. Both used Payen’s Flechair (an English con­traction of avion fleche or ‘arrow aircraft’) configuration that consisted of a trapezoidal fore-wing that housed the ailerons and a rear delta wing which contained the horizontal control surfaces. Payen had to rely on his salesmanship to gain access to material, wind tunnel time and other resources to build his aircraft as he had little money of his own to fund projects. Of course, the nature of his designs often made it a hard sell to the more conservative aviation industry. The Payen Pa. 100 Fleche Volante (‘Flying Arrow’) was his first aircraft to be built and was intended to be a racer to compete in the Coupe Deutsch de la Meurthe. Payen was able to borrow a 180hp Regnier R6 but the engine was later returned. He was then able to acquire a larger engine, a 380hp, 7-cylinder radial Gnome – Rhone 7KD Titan Major, but was too large for the Pa. 100. Payen had to seek donations (which he received) and rebuilt the Pa. 100 around the 7KD to create the Pa. 101. Unfortu­nately for Payen, the Pa. 101 failed to meet expectations. It finally took to the air on 17 April 1935, but on 27 April a hard landing broke the port landing gear and a fire broke out in the resulting crash gutting the Pa. 101. The accident saw Payen’s flight insurance revoked and so he went to work at the Bloch factory constructing a mock-up of the Pa. l 12 fighter that used two 150hp Salmson engines in tandem buried in the fuselage. The out­break of World War 2 saw the French military show no interest in this design.

The second aircraft was the Pa.22 which was the test bed for Payens proposed Pa. l 12 fighter. Originally to be powered by a ramjet, no such engine was available and a 180hp Regnier R6 engine was used instead. Payen constructed the Pa.22 in 1939 and the Ger­mans would later capture it after the invasion of France on 12 June 1940. The Germans, showing some interest in the design, test flew it on 18 October 1941 and found modifications were needed to correct poor longitudinal sta­bility. The aircraft was moved to Rechlin in Germany and after adjustments had been made to the cockpit position and the vertical stabiliser had been rebuilt the Pa.22 flew in the summer of 1942. After a number of short flights, the aircraft was wrecked in a crash landing. The Pa.22 was returned to France for repairs and was consequently abandoned by the Germans.

Prior to the outbreak of war, the Japanese had civilian and military personnel in France who studied and reviewed French aviation progress for possible use by Japan. This prac­tice went as far back as 1919 when Japan invited French military aviation instructors to teach the fledgling Japanese Army air force. The French also brought with them some of the latest aircraft that their country had avail­able. This training would forge a link between Japan and France that would last for many years, and it was by these means that the Japanese would learn of Payen’s work.

In 1938, Payen received a letter from Mit­subishi expressing an interest in his designs, notably the delta wing so often used in his air­craft concepts. A meeting was held between Payen, Commander Koshino and the captain of the UN corvette Sumikawa to talk about the Pa. l 12. During the discussions the UN inquired as to whether the Flechair design could be adapted to that of a two-seat, carrier borne, light bomber. The specifications required the aircraft to have the ability to take­off from and land on a deck space 80m (262ft) long, to have a range of at least 800km (497 miles), be capable of carrying a 800kg (1,7631b) torpedo or bomb and be Fitted with up to 180kg (396 lb) of armament.

Payen took the specifications and worked up a study to meet the UN requirements. The design was called the Payen-Mitsubishi Pa.400. This would have used two 670hp radial engines mounted one behind the other driving two, two-bladed, contra-rotating pro­pellers. For weapons, in addition to carrying the required torpedo or bomb, a nose mounted cannon (firing through the propeller hub), two machine guns per rear wing and a tail mounted machine gun were proposed. Endurance was to be 11-12 hours with a max­imum speed of 580km/h (360mph). Unlike his other Flechair designs, Pa.400 used staggered wings (his earlier offerings had the two wings level with each other). The study was reviewed and Payen was asked by Japanese representatives to obtain from the French gov­ernment the authorisation to export the tech­nical information for the Pa.400 study. This would have allowed the Japanese to further develop the Pa.400 in Japan. The authorisa­tion was granted on 28 September 1938, signed by the head of the cabinet of the Min­istry of Air. However, with the cloud of war on the horizon, Payen decided not to send the requested documents to Japan and it would appear the Japanese did not follow this up. To


all intents and purposes, the Japanese seemed to have lost interest in the Pa.400.

Why would the Japanese show an interest in the Pa. l 12 and the Pa.400 only to abandon it on the brink of receiving the technical infor­mation? There were several factors which the Japanese may have become aware of upon further review of Payen’s initial Pa.400 study. The first was that Japanese radial engines of the time did not have sufficient horsepower and, more importantly, were not of the correct size to fit into the Pa.400’s fuselage. Thus, the Japanese would have had to either construct a new radial engine or adapt the Pa.400 to use a Japanese engine, radial or not. A more per­tinent problem was the use of tandem radial engines. To make such an arrangement work­able required a considerable feat of engineer­ing and such designs making it to prototype form were exceedingly rare. Another factor concerned the poor visibility afforded the pilot given that the cockpit was situated far back in the fuselage which made landing a challenge at the best of times, let alone landing on a moving and rolling aircraft carrier. The rear wings and the long nose blocked side and downward vision, a serious liability in aerial combat, and the relatively short wingspan of the Pa.400 would not have offered much agility, a trait favoured by Japanese pilots and designers. In addition, the Japanese may have learned that the Pa. 101 was a flawed design and since the French military paid Payen no attention may have concluded there was nothing worth pursuing where the Pa.400 was concerned. Finally, it may have been the rad-

The Pa.400 depicted here is in the colours and markings as used on a Nakajima B5N2 torpedo bomber (known as Kate to the Allies) flown by Petty Officer First Class Toshio Takahashi from the carrier Hiryti during the attack on Pearl Harbor.

ical design of the Pa.400 that saw more con­servative UN officials directing Mitsubishi to focus their efforts on more conventional air­craft projects.

Enter the Suzukaze 20. A photograph of what was likely the Pa. 101 appeared in Japan in a printed document in the late 1930s. The caption for the photograph read ‘French Brand New Model Pey-yan 266th. Airplane No – mu 400 Horse Power’. The ‘Pey-yan’ was the phonetic spelling in Japanese of Payen while ‘No-mu’ was the phonetic spelling for Gnome. How it got to Japan is open to speculation but the two prevailing theories are that Payen, in trying to drum up funds for his work, made it available to a French diplomat to take to Japan to shop around to Japanese industry. Alternatively, the photograph was given to the UN by Payen during the discussions over the Pa.400.

The photograph – and perhaps other sources because Payen’s aircraft were shown in publications such as Bill Barnes: Air Adven­turer (from April 1935) – likely played a part in the rendering of the Suzukaze 20. The similar­ities to Payen’s designs cannot be ignored. For one, the Suzukaze 20 utilised two radial engines in tandem driving two, contra-rotat­ing propellers. Also, the Suzukaze 20’s cockpit was blended into the large, half delta-shaped vertical stabiliser, another Payen trait seen in the Pa. IOO/Pa. IOl and Pa.22. The artist likely removed the rear delta wing and slid the for­ward wings back and enlarged them since their shape is reminiscent of the Pa.400. With the exception of the nose, the fuselage shape of the Suzukaze 20 was similar to that of the Pa.400. Even the horizontal stabilisers of the Suzukaze 20 had a delta shape, perhaps a nod to the Pa. 101. However, whether or not the artist based the Suzukaze 20 on Payen’s designs may never be known for certain.


Horton HoX (Germany), Messerschmitt P. l 106 (Germany), Lippisch PI3a (Germany), BMW 803 engine (Germany), Wright R-2160 Tornado engine (US), Pratt & Whitney R-4360 Wasp Major engine (US), Butler – Edwards ‘Steam Dart’ (UK), Scroggs ‘Dart’ (US)

For the Mitsubishi-Payen Pa.400, based on the design study conducted by Payen.

Type Light Carrier Bomber

Crew Two


Two Gnome-Rhone 14 M4/5 radial engines, each developing 670*680hp maximum, driving two contra-rotating, two-bladed propellers


Span Length Height Wing area

















Max speed



at 4,950m

at 16,240ft

Max speed (one engine)



at 4,950m

at 16,240

Landing speed




12-14 hours





Five machine guns, two in each wing and one in the tail; one cannon firing through the propeller hub; one 800kg (1,764 lb) torpedo or bomb


None. The Suzukaze 20 was a fictional aircraft while the Pa.400 remained a design only.