Category Archives: Empire of Japan

A7He1 (He 112) in Japanese Service

Empire of Japan (1937)
Fighter Aircraft – Number Operated 30

During the war with China, the Japanese Air Forces encountered enemy fighters that were much better than what they currently had in their inventory. As their modern fighters were either under development or only available in limited numbers, they tried to acquire new fighters from aboard.  The options for acquiring such fighters were rather limited, and the Japanese turned to the Germans for a solution. This came in the form of 30 He 112 known in Japanese service as the A7He1.

The He 112 in Japanese service. Source: D. Bernard Heinkel He 112 in Action

A brief He 112 history

Before the Second World War, the Luftwaffe was in need of a new and modern fighter that was to replace the older biplane fighters in service, such as the Arado Ar 68 and Heinkel He 51.  For this reason, in May 1934 the RLM issued a competition for a new and modern fighter plane. While four companies responded to this request, only the designs from Heinkel and Messerschmitt were deemed sufficient. The Heinkel He 112 was a good design that offered generally acceptable flight characteristics and possessed a good basis for further improvements. The Bf 109 on the other hand had slightly better overall flight performance and was much simpler and cheaper to build. Given the fact that the Germans were attempting to accelerate the production of the new fighter, this was seen as a huge advantage over the He 112. Ultimately it would not be accepted for service, and only 100 or so aircraft would be built. These would be mainly sold abroad, with those remaining in Germany used for various testing and evaluation purposes.

He 112 the unsuccessful competitor of the Bf 109. Source: www.luftwaffephotos.com

While the He 112 project was canceled by the RLM, to compensate for the huge investment in resources and time into it, Heinkel was permitted to export this aircraft. A number of countries such as Austria, Japan, Romania, and Finland showed interest, but only a few actually managed to procure this aircraft, and even then, only in limited numbers.

Attempts to make a deal with Japan 

In 1937 a war between Japan and China broke out. While Japan had a better-equipped and more organized army, it faced stiff resistance. The Chinese were supported by the Soviet Union which supplied them with weapons and equipment, including aircraft. These caused huge concern within the Imperial Japanese Navy. Their newest fighters were either present only in small numbers or were still under development. As a temporary solution, IJN officials decided to approach Germany for assistance in the hope of acquiring new fighters.

For this reason, a military delegation was dispatched to Germany in the Autumn of 1937. Despite its later known fame, the German Air Force at that time was still in its early stage of rebuilding and realistically did not have much to offer, being in need of modern fighters themselves.  This would come in the form of the Messerschmitt Me 109. Its competing Heinkel He 112 lost the competition but was allowed to be sold abroad if anyone was interested. It was probably for this reason that the Japanese delegation visited the Heinkel factory at Marienehe. There they had the choice to observe the He 112 V9 aircraft. They were generally satisfied with what they saw and placed an initial order for 30 He 11Bs. If these proved to be as good as they hoped they would be, another, larger order for 100 more aircraft was to be given. As a confirmation of this agreement, the Japanese delegation returned with one He 112 aircraft that was to be used for familiarization and evaluation.

One of the 30 He 112 sold to Japan in 1938, Source: D. Bernard Heinkel He 112 in Action

Naming Scheme

As this aircraft was expected to enter service, it was designated as A7He1 by the IJN. The capital ‘A’ stands as a designation for a fighter. The number ‘7’ represents that this aircraft was to supersede the type 6 designation fighter. He stands for the Heinkel, and lastly the ‘1’ stands for the first variant of this type.  The Allied intelligence services discovered its existence within the IJP and awarded it the code name Jerry. 

Testing In Japan

Four aircraft arrived in 1937, and the last one arrived at the end of 1938. As the first aircraft began to arrive, the IJN began testing the A7He1’s performance in contrast to other fighters that they had in inventory, namely the Mitsubishi A5M2. While the A7He1 proved to be some 65 km/h faster, in other regards such as climbing speed and general maneuverability it proved equal or even worse than the Japanese fighter.  The Japanese were not satisfied with the A7He1 engine which was deemed too complex. These factors ultimately led the commission which examined it to propose that it should not be adopted, nor that any further orders should be given. After the arrival of the last A7He1, the order for an additional 100 aircraft was canceled.

Ultimate Fate 

As the A7He1 was not adopted for service, the IJN had to decide what to do with the 30 aircraft. They still represent a financial investment that could not be simply discarded. Some of these were allocated to various research institutes for future studies and evaluation, the remainder were given to training schools. None were ever used operationally in combat either in China or in the Pacific.

Quite surprisingly given their age and the rather limited numbers that were acquired, a few He1 survived the war and were captured by the Allies. One example was found in Atsugi airfield near Honshu in early October 1945. Unfortunately, the fate of these captured aircraft is not known but they were likely scrapped at some point after the war.

Despite the limited number of acquired aircraft, some of them survived the war and were later captured by the Allies. Source: www.destinationsjourney.com
Another aircraft (on the left) is being photographed by the Allied soldiers. It is possible that it was the same aircraft as in the previous photograph just taken later when it was being scraped. Source: www.destinationsjourney.com

Technical Characteristics

The He 112 was an all-metal single-engine fighter. The monocoque fuselage consisted of a metal base covered by riveted stress metal sheets. The wing was slightly gulled, with the wingtips bending upward, and had the same construction as the fuselage with a combination of metal construction covered in stressed metal sheets.

During its development life, a great number of engines were tested on the He 112. For the main production version, the He 112 B-2, the 700 hp Jumo 210G liquid-cooled engine was used, and some were equipped with the  680 hp Jumo 210E engine. The He 112 had a fuel capacity of 101 liters in two wing-mounted tanks, with a third 115-liter tank placed under the pilot’s seat.

The landing gear was more or less standard in design. They consisted of two larger landing wheels that retracted into the wings and one semi-retractable tail wheel. The He 112 landing gear was wide enough to provide good ground handling and stability during take-off or landing.

The cockpit received a number of modifications. Initially, it was open with a simple windshield placed in front of the pilot. Later models had a sliding canopy that was either partially or fully glazed.

While the armament was changed during the He 112’s production, the last series was equipped with two 7.92 mm MG 17 machine guns and two 2 cm Oerlikon MG FF cannons. The ammunition load for each machine gun was 500 rounds, with 60 rounds each for the cannons. If needed, two bomb racks could be placed under the wings.

Conclusion

While the He 112 was often portrayed as a modern fighter, from the Japanese point of view it proved to be disappointing in any case. While expecting a potentially effective fighter that was better with everything they had, the He 112 proved to be quite the opposite. After the 30 aircraft arrived no further orders were given. This only serves to prove that the old saying the grass is always greener on the other side is correct once in a while.

He 112B-2 Specifications

Wingspans 29  ft 10  in / 9.1 m
Length 30  ft 2 in / 9.22 m
Height 12 ft 7 in  / 3.82  m
Wing Area 180  ft² / 17 m²
Engine One 700 hp Jumo 210G liquid-cooled engine
Empty Weight 3,570  lbs / 1,620 kg
Maximum Take-off Weight 4,960 lbs / 2,250 kg
Climb Rate to 6 km In 10 minutes
Maximum Speed 317 mph / 510 km/h
Cruising speed 300 mph / 484 km/h
Range 715 miles / 1,150 km
Maximum Service Ceiling 31,170 ft / 9,500 m
Crew 1 pilot
Armament
  • Two 20 mm (1.8 in) cannons and two machine guns  7.92 mm (0.31 in) machine guns and 60 kg bombs

 

He 112 v5 as it was tested by Japan

Credits

  • Written by Marko P.
  • Edited by  Henry H.
  • Illustrations by Godzilla

Source:

  • Duško N. (2008)  Naoružanje Drugog Svetsko Rata-Nemаčaka. Beograd
  • J. R. Smith and A. L. Kay (1990) German Aircraft of the Second World War, Putnam
  • D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books
  • D. Bernard (1996) Heinkel He 112 in Action, Signal Publication
  • R.S. Hirsch, U, Feist and H. J. Nowarra (1967) Heinkel 100, 112, Aero Publisher
  • C. Chants (2007) Aircraft of World War II, Grange Books.
  • https://airpages.ru/eng/lw/he112_combat_use.shtml

 

Maeda Ku-6

 Empire of Japan (1943)
Experimental Glider Tank – One Mock-up Model

While tanks can provide excellent offensive firepower, they can’t always be easily transported to where they are needed. In the case of Japan during WW2, this was usually achieved by using ships and rail lines to transport them to where they were needed. Facing difficult terrain and disrupted shipping routes, the concept of a flying tank became a promising concept to the Japanese military hierarchy. By transporting tanks via the air, they could potentially offer benefits to the airborne troops, who were often left without proper heavy support. An exploration of this concept would lead to the creation of the Maeda Ku-6 tank glider.

The Concept of Airborne Operations

The American M22 Locust light airborne tank. (Source: Wikimedia)

The practice of dropping airborne troops behind enemy lines offers many tactical advantages, as they can attack weak points and enemy supply lines. This in turn would force the opposing side to redistribute its own forces away from the front to deal with this problem. On the other hand, airborne forces often lack proper artillery or armor support, making them vulnerable to well-equipped and directed enemies. Some nation armies responded to this by employing glider transportable light field artillery and even recoilless, high caliber guns. Transporting armored vehicles proved a more daring task to implement. Most tanks could not be easily carried inside a transport plane or even parachuted due to their weight and size. The American and British responded by developing lightly armored and armed tanks, such as the M22 Locust or the Light Tank Mk VII Tetrarch. The Soviet Union, on the other hand, designed an auxiliary glider contraption that would be used to transport a heavier tank, the Antonov A-40. This principle would also be tested by the Japanese Army during the war, which led to the creation of the Maeda Ku-6 project.

Antonov’s flying tank was unsuccessfully tested by the Soviets. (Source: Wikimedia)

Airborne Japan

The Japanese began the development of cargo glider designs for military use in 1937. Following the successful use of gliders by the Germans during their conquest of the West in May 1940, the Imperial Japanese Army began developing new gliders in June 1940. In response to this, the Imperial Japanese Navy began its own project soon after. In Japanese terminology, these were designated Kakku (English: to glide).

Both the IJA and IJN had and used parachute infantry units. It is important to note that these were relatively small units that were rarely employed in their intended role. For these reasons, their equipment was more or less the same as that of ordinary infantry formations. They saw the most active service during the fight for the Dutch East Indies in 1942. These were mainly used to capture various vital strategic points, such as airfields or weakly defended positions deep in the enemy’s rear line. Following the end of this campaign, the Japanese did not use paratrooper units in their primary role.

Japanese paratrooper IJN units had two notable deployments: in the successful Battle of Manado from 11th to the the12th January 1942, on Celebes Island, also known as Sulawesi, and in the Battle of Timor from19th February 1942-10th February 1943, where IJN paratroopers suffered heavy casualties. Their IJA counterparts were used more as a commando unit and were only ever airdropped during the invasion of Sumatra in February 1942.

Map of Japanese expansion by 1942. Some of these offensive operations also included the use of parachute units, albeit to a limited extent. (Source: https://www.pinterest.com/pin/389350330265435193/)

In 1943, attempts were made to increase their firepower, though, it is unclear how much impact the experiences from the airborne operations of February 1942 had. It was proposed to use specially designed glider tanks that could be flown to their designated target and thus provide necessary firepower to otherwise weakly armed paratrooper formations. In addition, this vehicle could be airlifted to any other theater of war without a need for them to be transported by ships, which were by this time, seriously endangered by the US Navy.

The Maeda Ku-6

The project was initiated by the Army Head Aviation Office in collaboration with the Fourth Army Research Center. The first drawings of this new design were soon ready and were allocated to the Maeda research center for the construction of a working prototype. In the early stage of development, the new tank was to be transported by a specially designed glider. But as Maeda was unable to create a glider that could transport a light tank, and so another solution was needed. Maeda engineers suggested another approach to this problem. As no glider could be developed to carry a tank, maybe the tank itself could be modified to use a glider.

While Maeda was responsible for the glider development, the design of the tank was given to Mitsubishi Heavy Industries. It is unclear if it was a completely new tank design or if Mitsubishi reused some of the existing vehicles that were in service. According to the Japanese Army and Navy Aircraft Complete Guide, the Type 98 light tank was used for the project. This tank was intended as a replacement for the Type 95 Ha-Go, but this was never achieved as it was built too late and in very small numbers.

The Type 98 light tank on which the Ku-6 was allegedly based. (Source: Wikimedia)

Name of the Project

According to E. M. Dyer, the new light tank was designated as So-Ra (Sora-Sha), which could be translated as the “sky” or “air” tank. The whole project would be designated Kuro-Sha, with the Ku and Ro, meaning the number ‘6’, taken from the Ku-6 glider designation. Lastly, the Sha stands for “tank”. An older source, J. E. Mrazek, mentions that the tank design originated in late 1939. According to Mrazek, the tank was initially designated ‘special Tank project 3’. It received the Sora-Sha designation before being changed to Kuro-Sha (English: Black Vehicle).

Technical Specification

The Ku-6 was designed as a tank transport glider. While not specified, it is likely that the Ku-6 would have been made out of wood. Due to the losses of the original documents, not much is known about its overall design. Over the years, historians based on available information devised two different designs of how this contraption may have looked.

The tank itself, due to its nature of use, had to be as light as possible. This means it would have been lightly armored and armed. The So-Ra’s total weight was slightly above 3 tonnes and would have been operated by two crew members. The driver was positioned in the front of the vehicle. He was also responsible for piloting the whole glider. Behind him, in the turret, was the commander, who was responsible for operating the main armament. This small crew would have greatly affected the tank’s overall performance. Given the limitation in size and weight, adding more crew members was not possible. In normal circumstances, the driver’s vision ports would have been small and protected. In this case, he would need to have a good and unobscured overall view of his surroundings. For this reason, he was to be provided with three large viewports. The armor was to be less than 12 mm thick. While its armament consisted of one 37 mm gun, along with a machine gun, a possible installation of a flame thrower was also considered.

The wooden mock-up of the Japanese airborne tank project. (Source: https://www.armedconflicts.com/Maeda-Ku-6-t41347)

As the tracks would cause massive drag during take-off, specially designed sleds would be attached to them to facilitate an easier take-off. According to the first proposals, the tank itself was designed to act as an improvised glider fuselage and the wings and the tail assembly would be attached to it.  The tank crews would be provided with wired controls installed inside the vehicle in order to pilot it. In front of the tank, a towing cable would be added to connect it to the glider tug.

In the first version, the wings were to be attached to the So-Ra sides with the tail assembly to the rear. (Source: https://www.armedconflicts.com/Maeda-Ku-6-t41347 https://imgur.com/a/xaLcNcO)

The second version is completely different. Above the tank, a larger wing with a twin tail boom was added. These two components would be connected by struts. In both cases, once the tank hit the ground, the wing assemblies could be easily removed, which meant that the tank could immediately go into action with relative ease.

The second version was completely different in appearance. (Source: https://www.armedconflicts.com/Maeda-Ku-6-t41347)

It is unspecified which material would be used during the whole wing assembly. Given its rather late introduction and Japanese limited resources at this point, wood would likely be used.  With the whole wing assembly, the Ku-6 had a length of between 12.8 to 15 m (depending on the source) with a width of 22 m and a height of 3 m. The wing area was around 60 m².

The maximum towing speed at heights of 4 km was 250 km/h. The maximum speed that could be achieved during the gliding flight itself was 174 km/h. The decent speed at 4 km altitude was 2.8 sec/m while at lower heights closer to the ground it was 2.6 sec/m. It is important to note that these are projected figures.

Testing and Project’s Fate

Due to the slow pace of work, the first operational glider prototype was completed in 1945. The tank itself was not ready by this time. As a temporary solution, a wooden mock-up of it with ballast was intended to be used instead. The prototype was taken to the sky by a Mitsubishi Ki-21 medium bomber. Almost from the start, the Ku-6 (according to E. M. Dyer the second variant was used) proved to have poor overall flight characteristics, and the pilot had a poor view. Lastly, as it was specially designed to carry the So-Ra, its transport capacity for other vehicles was very limited. The IJA officials quickly became disinterested in the Ku-6, focusing instead on the Ku-7 general purpose glider which looked more promising. Another aspect that we must take into account was the poor state of the Japanese Army in 1945. By this point, it was so battered and depleted, that undertaking an airborne operation was an impossible task. In the end, the Ku-6 would be terminated and the fate of the single prototype is unknown, but it was either scrapped or lost during Allied bombing raids.

The prototype was taken to the sky using a Mitsubishi Ki-21 aircraft. (Source: Wikimedia)
The Ku-7 was a more orthodox glider design. While they were built in small numbers, they would be mainly used for testing and were not used operationally by the Japanese Army. (Source: https://listverse.com/2015/09/29/10-goofy-warplanes-of-world-war-ii/)

Conclusion

The Ku-6 seems like an interesting concept that could have offered a number of benefits to the Japanese in the early years of the Pacific theater. By 1943, when the project was initiated, the war situation for Japan had rapidly deteriorated, with the Allies pressing on all sides. In reality, the Ku-6 proved to be too flawed in design. It was difficult to control and the pilot had poor visibility. Given that it was a glider, it would make an easy target for Allied fighters which, by its construction time, had almost complete air supremacy.

 

Specification Maeda Ku-6
Wingspan 22 m / 72 ft 1 in
Length 15 m / 42 ft
Height 3 m / 9 ft 8 in
Wing Area 60 m² / 645 ft²
Maximum Takeoff Weight 4.200 kg / 9.260 lbs
Maximum Gliding Speed 174 km/h / 108 mph
Maximum Towing Speed 250 km/h
Crew Two pilot/driver and the commander /gunner
Maeda Ku-6 hypothetical side wing configuration
Proposed version with the top wing construction.

 

Credits

  • Written by Marko P.
  • Edited by Henry H. & Medicman11.
  • Illustrated by Godzilla

Sources

  • D. Nešić (2008), Naoružanje Drugog Svetsko Rata-Japan, Beograd
  • E. M. Dyer (2009) Japanese Secret Projects Experimental Aircraft of the IJA and IJN 1939-1945, Midland
  • J. E. Mrazek (1977) Fighting Gliders of World War II, ST Martin Press
  • S. J. Zaloga (2007) Japanese tanks 1939-45, New Vanguard
  • Tomio Hara’s Japanese Tanks 1978
  • Japanese Army and Navy Aircraft Complete Guide
  • L. Ness (2015) Rikugun Guide To Japanese Ground Forces 1937-1945, Helion and Company

Nakajima Ki-115 Tsurugi

 Empire of Japan (1945)
Kamikaze Aircraft – 105 Built

The Ki-115 suicide aircraft [Combat Workshop via Pinterest]

Throughout 1945, it was becoming clear to Japanese Army Officials that an Allied invasion of the Japanese mainland was growing ever more likely. Seeing as their navy and airforce had been mostly destroyed, they needed new weapons to fight off a probable Allied attack on Japan. Among these new weapons were Kamikaze aircraft, with many older designs having already been used in this role. However, some Kamikaze aircraft were to be specially designed for such a role, being cheap and able to be built quickly and in great numbers. One such aircraft was the Ki-115 Tsurugi (Sabre) which was built in small numbers, and never used operationally.

History

Rear view of Ki-115 suicide aircraft [ijaafphotos.com]
Following the extensive loss of men, materiel, and territory during the fighting in the Pacific, the Japanese Army and Navy were in a precarious situation, especially as there was a great possibility of an Allied invasion of their homeland. Unfortunately for them, the Japanese fighting forces on the ground, in the air, and on the sea were mostly mere shadows of their former selves, unable to prevent the rapid Allied advance across the Pacific. This was especially noticeable after the costly Japanese naval defeat during the Battle of Leyte Gulf in October 1944 and later Battle of Okinawa which ended in July 1945.. The desperation, or better said fanatical refusal to accept that the war was lost, led to the development and use of Kamikaze (divine wind) tactics. This name was taken from Japanese history, the term arose from the two typhoons that completely destroyed the Mongol invasion fleets.

Essentially, the Kamikaze were Japanese pilots that used their own explosive-laden aircraft as weapons, and sought to crash into important targets, such as Allied warships. This term also entered widespread use to designate all Japanese suicide craft used in this way. During the war, these tactics managed to sink over 30 Allied ships and damage many more.

Allied anti-aircraft fire was often concentrated in order to prevent Kamikaze attacks. But, despite this, Japanese aircraft would often get through. [Wiki]
The suicide attacks were mostly carried out using any existing aircraft that was operational, including older trainers and obsolete aircraft. Kamikaze are a subject with a great deal of nuance and can be difficult to understand through a conventional lens. However, supplies of these aircraft would inevitably become limited and their previous usage meant fewer would be serviceable compared to newer, more expensive models. Thus, the Japanese Army wanted a specially designed Kamikaze aircraft that could be produced in great numbers. These aircraft needed to have a simple construction and use as little of dwindling material stockpiles as possible.

On 20th January 1945, the Japanese Army contacted the Nakajima aircraft manufacturer with instructions to design and build such an aircraft. The basic requirements included a bomb load up to 800 kg (1,760 lbs). It had to be able to be powered by any available radial engine in the range of 800 hp to 1,300 hp. The maximum speed desired was 515 km/h (320 mph). Construction and design had to be as simple as possible. They also wished to speed up the whole development and production process and also to reduce the need for skilled labor. It was especially emphasized that the undercarriage had to be jettisonable, not retractable. It was not expected for the aircraft to fly back, so a retractable landing gear was not needed and this would make the production and design process somewhat quicker.

First Prototype

The job of designing this aircraft was given to Engineer Aori Kunihiro. He was supported by engineers from Ota Manufacturing and the Mitaka Research Institute. While Nakajima received the contract in January 1945, it only took two months to complete the first prototype. In March 1945, this prototype was presented to the Japanese Army and then put through a series of tests. Almost immediately, a series of faults with the design were noted. This was not surprising given that the whole design process lasted only two months. During running on the ground, the fixed and crude undercarriage was difficult to control. The pilot’s poor frontal visibility further complicated matters. This was unacceptable even for skilled pilots, while less experienced pilots would have had great difficulty in successfully operating it on the ground. The Army rejected the prototype and requested a number of modifications to be done.

The Ki-115 first prototype. [ijaafphotos.com]
The Ki-115 cockpit was positioned in the middle of the fuselage and offered the pilot limited forward vision when on the ground. [Wiki]

Technical Specifications

The Ki-115 was designed as a low-wing mixed construction suicide attack aicraft. The front fuselage, containing the engine compartment, and the central part were built using steel panels. The engine compartment was held in place by four bolts and was specially designed to house several different potential engines. Eventually, the Japanese chose the 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine. It had a fixed-pitch three blade propeller. In order to help reach its target quicker, two small auxiliary rocket engines were placed under each wing.

The wings were built using all-metal construction with stressed skin. The rear tail unit was built using wood and was covered by fabric. The cockpit was placed in the upper centre of the fuselage. It was semi-open, with a front windshield.

As requested, the Ki-115 prototype had a fixed and jettisonable undercarriage. It had a very simple design, using simple metal tubes with no shock absorbers. While two wheels were used in the front, a tailskid was used at the rear. The fixed undercarriage tested on the prototype proved to be highly ineffective. All later produced aircraft were instead equipped with a simple and easy to build shock absorber.

Ki-115 side view [ijaafphotos.com]
The armament consisted of a bomb load of up to 800 kg (1,760 lbs). This included using either a single 250 kg (550 lb), 500 kg (1.100 lb) or 800 kg (1.760) bomb. The bomb was not to be dropped on the enemy, but instead be detonated once the aircraft hit its target. Beside the bomb, no other armament was to be provided on the Ki-115.

The Ki-115 was initially meant to be supplied with a fixed undercarriage, which proved to be problematic. Production aircraft were instead provided with simple shock absorbers. [ijaafphotos.com]

The Fate of the Project

Once the prototype was back in Mitaka Kenkyujo (where the prototype was built), the engineers began working on improving its performance. The redesigned undercarriage, which incorporated a simple shock absorber, was completed by June 1945, by which time a series of test flights were done. By August 1945, some 104 Ki-115 aircraft were ready. Two Ki-115s were given to Hikoki K.K., where the Japanese Navy Air Force was developing its own suicide attack aircraft. By the war’s end, none of the Ki-115s built would be used in combat.

Surviving Aircraft

The Ki-115 planes were later captured by the Allies, and nearly all were scrapped. Surprisingly, two Ki-115s have survived to this day. One can be seen at the Pima Air & Space Museum. This aircraft is actually on loan from the National Air and Space Museum. The second aircraft is currently located in Japan. Not wanting to potentially damaged tis aircrafts on the side of caution no restoration attempts are planned for the near future.

The surviving Ki-115 at the Pima Air & Space Museum. [Wiki]
A picture of the second surviving aircraft taken during the 1980’s in Japan. [hikokikumo.net]

The Ki-115b Proposal

In order to further improve the aircraft’s performance and reduce cost, the Ki-115b version was proposed. This included replacing the all-metal wings with ones built of wood. These new wings were larger and had to be equipped with flaps. To provide the pilot with a better view, his cockpit was moved to the front. Due to the end of the war, nothing came from this proposal.

Production and Modifications

The Ki-125 was built in small numbers only, with some 104 production planes plus the prototype. These were built by the two Nakajima production centres at Iwate (22 aircraft) and Ota (82 aircrafts). The production lasted from March to August 1945.

  • Ki-115 prototype – Tested during early 1945.
  • Ki-115 – In total, 104 aircraft were built, but none were used operationally.
  • Ki-115b – Proposed version with larger wooden wings, none built.
Only 105 Ki-115 aircraft, including the prototype, were ever built. [ijaafphotos.com]

Conclusion

Luckily for the Japanese pilots, the Ki-115 was never used operationally. It was a simple and crude design which was born out of desperation. If the Ki-115 was ever used in combat, it would have likely presented an easy target for enemy fighters and suffered from poor reliability due to its cheap construction.

Ki-115 Specifications
Wingspan 28 ft 2 in / 8.6 m
Length 28 ft 1 in / 8.5 m
Height 10 ft 10 in / 3.3 m
Wing Area 133.5 ft² / 12.4 m²
Engine One 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine
Empty Weight 3,616 lbs / 1,640 kg
Maximum Takeoff Weight 6,440 lbs / 2,880 kg
Maximum Speed 340 mph / 550 km/h
Cruising speed 186 mph / 300 km/h
Range 745 miles / 1,200 km
Crew Pilot
Armament
  • Bomb load up to 1,760 lbs (800 kg)

Gallery

Illustrations by Ed Jackson

Another Ki-115 Tsurugi in Natural Metal with 500kg Type 92 Bomb
Ki-115 Tsurugi in Green with 500kg Type 92 Bomb
Ki-115 Tsurugi in Natural Metal with 500kg Type 92 Bomb

Credits

  • Written by: Marko P.
  • Edited by: Stan L. & Henry H.
  • Illustrations by Ed Jackson

Sources

  • R. J. Francillon (1970) Japanese aircraft of the Pacific war, Putham and Company
  • D. Nešić (2007) Naoružanje Drugog Svetskog Rata Japan, Tampoprint
  • D.Mondey (2006) Guide To Axis Aircraft Of World War II, Aerospace Publishing

 

 

 

Gasuden Kōken-ki

 Empire of Japan (1937)
Long Range Research Aircraft- 1 Built

The Gasuden Kōken-ki was Japan’s attempt at building a world record setting plane for the longest distance covered in a non-stop flight. First conceived in 1931 to surpass John Polando and Russell Boardman’s flight, the Kōken-ki would have a slow development finally completed and ready for flight on August 8th of 1937. Though 6 years late and many other world records for distance had been set, the Kōken-ki still managed to prove its worth on May 13th of 1938 where it made a non-stop flight in a closed-circuit course in Japan covering 7239.58 mi (11651.011 km), a record that Japan would hold until 1939.

History

In the 1920s and 1930s, many countries were competing against each other for setting aviation-related world records, be it endurance, speed or distance. The goal of establishing a long distance world record was one of the most popular ambitions a country could have. The 1931 world record was established by John Polando and Russell Boardman, flying a Bellanca J-300 Special nicknamed “Cape Cod” from Floyd Bennett Field in New York to Istanbul, Turkey. The distance covered by these two men spanned 5011 miles (8066 km). The Empire of Japan was by no means idle in the conquest for setting the world record. The Kōkū Kenkyūjo (Aeronautical Research Institute) began to formulate a design proposal in the latter half of 1931 for a plane that would be able to beat Polando and Boardman’s record flight. The Kōkū Kenkyūjo was on good terms with the Tokyo Imperial University, and convinced them to put their design forward to the Monbushō (Ministry of Education). The design proposal moved rapidly through the approval process and eventually made its way to the Kokkai (Diet). Relatively confident in the design, the Kokkai approved the Kōkū Kenkyūjo’s design and provided them with a monetary grant.

A factory worker fitting parts on the tail section of the Kōken-ki. (Arawasi)

With adequate funding and support of the government, the Kōkū Kenkyūjo began to formally investigate the matter of designing the plane. The plane was now named the Kōken-ki (航研機). The man responsible for overseeing the project was Dr. Koroku Wada, with professor Keikichi Tanaka assisting him. Many members of the design staff were from the engineering department of the Tokyo Imperial University. Various committees were also formed for the purpose of designing the Kōken-ki. It would take two years until the basic design was completed. By the time the design was finished in August of 1934 however, another world record had been set by French aviators by the names of Maurice Rossi and Paul Codos. The French aviators were able to surpass the previous record set by Polando and Boardman by 645 miles / 1038 km by flying their Blériot 110 monoplane from New York to Rayak, Syria on August 5th of 1933. The Japanese were confident that they would soon be able to best this record, as they’d designed the Kōken-ki to endure 8078 miles (13000 km) of flight.

The next step for the Kōken-ki was construction, but this process would be slow as the advanced design of the Kōken-ki had to be completed first. Various components and tooling would be manufactured the following year. The Tokyo Gas and Electric Industry (known as Gasuden) was selected to be the manufacturer of the airframe, while Kawasaki Kokuki KK. was selected to manufacture the powerplant, which would be a licensed Japanese made version of the German BMW VII engine. Once the advanced design was completed, construction began. Due to the fact that Gasuden was relatively inexperienced with metal fabrication, the construction of the Kōken-kid would be delayed. The major components of the Kōken-ki were finally completed on March 31st of 1937, and were promptly moved to a hanger owned by the Teikoku Kaibo Gikai (Imperial Maritime Defence Volunteer Association) at Haneda Airport where it was to be assembled. On August 8th of 1937, the assembly was completed and the Kōken-ki was ready for its maiden flight.

Test pilots for the plane were carefully selected as testing the potential record setter was a matter of great importance to the Japanese. A decision was finally made with Major Yuzo Fujita as the pilot, Master Sergeant Fukujiro takahashi as the co-pilot and Flight Engineer 

From left to right is Major Fujita Yuzo, Flight Engineer Sekine Chiaichi and Master Sergeant. (Arawasi)

Chikakichi Sekine as the flight engineer. All of these men belonged to the Imperial Japanese Army’s Rikugun Kokugijutsu Kenkyū (Air Technical Research Institute) and had been involved with the design of the Kōken-ki since the start. The long awaited maiden flight finally took place on May 25th of 1937. The test flight went well with no problems to report, so plans for the Kōken-ki’s official record setting flight was set in motion. More test flights had to be completed, so the three men continued fly the Kōken-ki. Meanwhile, the Soviet Union’s own Tupolev ANT-25 made its record flight on June 18th of 1937 where it flew from Moscow over the North Pole and landed in Vancouver, Washington. This flight took the Russian pilots 63 hours and covered 5670 mi (9130 km). The Japanese however, were not concerned as the Kōken-ki’s range was surely able to surpass this. 

The first attempt for setting the world record was conducted by Japan on November 13th of 1937. Unfortunately for the Japanese, a landing gear failure surfaced and the Kōken-ki had to be grounded for months until May 10th of 1938. This second attempt was also met with a problem, as the autopilot system malfunctioned. This problem was far simpler to remedy than the landing gear, and was rapidly repaired. On May 13th at 4:55 AM, the Kōken-ki successfully took off from Kisarazu Naval Air Base near Tokyo Bay to break the world record. To verify the authenticity of the flight, Imperial Japanese Navy Lieutenant-Commander Tomokazu Kajjiki was to monitor the

A poster advertising Nisshin’s salad oil, with the Kōken-ki displayed in the background. (Arawasi)

flight as he was the Fédération Aéronautique Internationale’s (World Air Sports Federation) representative for Japan. The flight plan of the Kōken-ki was to follow a square shaped course that would lead to Choshi from Kisarazu, then to Ohta and back to Kisarazu. Many minor problems occurred during the flight, such as a tear in the water cooler. The Kōken-ki flew the square course for 29 laps nonstop, and finally completed its task of setting the world record, amassing a total distance of 7239.58 mi (11651.011 km). The Kōken-ki landed back at Kisarazu at 7:21 PM of May 15th after almost 63 hours. Upon landing, the flight of the Kōken-ki was officially approved as a world record by the FAI. It is noteworthy that the Kōken-ki was reported to still have about 132 US gallons (500 L) of fuel left, meaning that it could have potentially flown another 745 mi (1200 km). Nonetheless, it was an achievement which made the nation proud. The Kōken-ki was then featured on many advertisement posters in Japan.

The Japanese were able to hold the world record for about 15 months before being beaten by the Italians in August of 1939. The Italians flew a Savoia-Marchetti SM.82 and covered a distance of 8038 mi / 12936 km over a closed-circuit course. Nonetheless, the flight by the Kōken-ki was still an incredible feat for the Japanese, as it was the first and only Japanese plane to obtain a FAI world record at the time. After the record setting flight, the Kōken-ki would mostly remain in the Kaibo Gikai hangar where it was first assembled. Occasionally, the Kōkū Kenkyūjo would and perform test flights for various purposes. After the Kōken-ki was past its prime, the Japanese wanted to see if they could further improve their long distance flight. In the eyes of professor Hidemasa Kimura, the Kōken-ki was only useful for challenging the world record for distance, but not for anything else. As such, Kimura decided to design a plane which would be capable of flying from Tokyo to New York, a route spanning 6737 mi (10842 km). The work of this would result in the Tachikawa Ki-77, or A-26.

From left to right, Chikaichi, Takahashi and Fujita receiving the Japanese “Yokosho” medal for their feat. (Arawasi)

The Kōken-ki flew for the last time on June 14th of 1939 as a commemoration for Major Fujita, the pilot of the record flight who was killed in combat in China.  After Major Fujita’s funeral flight, the Kōken-ki was stored in the Haneda Airport and remained there for the entire duration of World War II in relatively pristine condition. However after Japan surrendered, American occupational forces began to arrive and began a long process of demilitarizing Japan. Upon reaching Haneda airport, all of the Japanese planes there ,military or not, were targeted for destruction. The Kōken-ki and every other Japanese plane present at the airport was towed to the field and burnt in a mass pile, thus bringing an ungraceful end to the Kōken-ki.

Design

A closeup on the Kawasaki-built BMW VIII engine.

The Gasuden Kōken-ki had an all-metal semi-monocoque fuselage which housed a Kawasaki-built German BMW VIII engine driven by a Sumitomo SW-4 two-bladed metal-shrouded wooden propeller. The wings of the Kōken-ki were carefully designed with the intent of allowing it to operate in thinner air. The cantilever wings were constructed using a Kōken-ki Model 4 aerofoil shape, with about 17.5% thickness. The wingtips however, had a different material which was Kōken-ki Model 11 alloy. This aerofoil only had 4% thickness. The resulting wings had an aspect ratio of 8.7. As the plane was designed with range and endurance in mind. 14 fuel tanks were installed in the wings allowing for 1538 US gallons (5822 L) of fuel. A system was also installed which would allow the fuel to even out in all the tanks in order to maintain center of gravity. The landing gear of the Kōken-ki was retractable in order to reduce drag and once retracted, fairings would cover the landing gear wells. The cockpit was set on the left side of the plane, giving it an asymmetrical design. The Kōken-ki’s windshield could be extended and folded in order to reduce drag. Only when taking off and landing would it be extended. This design was a hindrance for the pilots as they reported poor visibility and control. The Kōken-ki was completely metal, with the exception of fabric covers which were fitted over the control surfaces and wings.

Operators

  • Empire of Japan – The Gasuden Kōken-ki was operated solely by Japanese pilots for all the flights it flew.

Gasuden Kōken-ki

Wingspan 91 ft 7 in / 27.9 m
Length 49 ft 5 in / 15.1 m
Height 11 ft 9 in / 3.6 m
Wing Area 939.7 ft² / 87.3 m²
Wing Loading 21.6 lb/ft² / 105.9 kg/m²
Power Loading 25.3 lb/hp / 11.5kg/hp
Engine 1x Kawasaki-built BMW VIII 12-cylinder water cooled V-engine (715 hp)
Propeller 1x Sumitomo SW-4 two-bladed metal-shrouded wooden propeller
13 ft 1.5 in / 400 cm
Fuel Load 1538 US gallons / 5822 L
Empty Weight 9314 lb / 4225 kg
Loaded Weight 20317 lb / 9216 kg
Maximum Speed 155 mph / 250 kmh at Sea Level
152 mph / 244 kmh at 6562 ft / 2000 m
Cruising Speed 131 mph / 211 kmh at 6562 ft / 2000 m
Range 8078 mi / 13000 km
Maximum Service Ceiling 11187 ft / 3410 m
Crew 1x Pilot
1x Co-Pilot
1x Flight Engineer

Gallery

Kōken-ki sideart by Ed Jackson
The Kōken-ki being prepped for flight by ground crew and an armed guard. (Arawasi)
The Kōken-ki taking off. (Arawasi)
Underside view of the Koken with its gear retracted.
The Kōken-ki in the factory during construction. Note the exposed engine. (Arawasi)
Engineers working on the Kōken-ki. (Arawasi)
A poster advertising Nitto’s black tea. The Kōken-ki is featured in the background. (Arawasi)
A 1939 postage stamp commemorating the Kōken-ki’s record flight. (Arawasi)
A replica of the Koken-ki on display in a museum in Japan

A Series of Youtube Videos on the World Record Attempt:

Sources

Takenaka, K. (2007). Koken Long-range Research-plane.Swopes, B. (2017). 13–15 May 1938.Tupolev ANT-25 Soviet Long Range Record Setter. (n.d.). Fiddler’s Green.Mikesh, R. C., & Abe, S. (1990). Japanese aircraft, 1910-1941. Ann Arbor, MI: Naval Institute.Dyer, E. M. (2015). Japanese Secret Projects: Experimental Aircraft of the IJA and IJN 1922-1945. Ian Allan Publishing. Images: Side Profile Views by Ed Jackson – Artbyedo.com, Other images from http://arawasi-wildeagles.blogspot.com/

 

Mitsubishi G7M “Taizan”

 Empire of Japan (1941)
Strategic Bomber- 1 Scale Mockup Built

The Mitsubishi G7M “Taizan” (泰山/Great Mountain) was a planned long range strategic bomber for Imperial Japan’s Army Air Service. Developed out of the need for a bomber capable of striking the continental United States, the Taizan would face a series of developmental problems, ultimately leading to the cancellation of the project.

History

Prior to the start of World War II, Japan had foreseen that in a potential future conflict with the United States, it would require a long range bomber capable of striking the US mainland. In order to fulfill this requirement, a review was conducted in 1941 of all the Imperial Japanese Navy’s bomber aircraft in service. It was revealed that the entirety of the Japanese bomber arsenal was incapable of striking targets in the United States from the Japanese airfields. The Mitsubishi G4M “Betty” was one of Japan’s newest aircraft being pushed into service. Despite its superior range of 3,749 mi (6,043 km) compared to previous IJN bombers, it still was not sufficient enough to strike the US mainland or targets deep in the Soviet Union. As a result of this, the Naval Kōkū Hombu (Aviation Bureau) issued the 16-shi specification in 1941 for a long range bomber. The 16-shi specification would call for a bomber capable of flying at least 361 mph (580 km/h) with a maximum range of 4,598 mi (7,340 km).

Interested in this specification, Mitsubishi’s staff began work on a design that would meet the criteria set by the Kōkū Hombu. Mitsubishi engineer Kiro Honjo (the designer of the G3M and G4M) proposed a four engine design, but this was promptly rejected by the Kōkū Hombu. As a result, another Mitsubishi engineer by the name of Kijiro Takahashi submitted his own design. Upon inspection by the Kōkū Hombu, Honjo’s design was approved and given the green light to proceed. Within Mitsubishi, the 16-shi design was known as the “M-60”. Takahashi’s design was to be powered by two “Nu” engines. The Nu was a 24 cylinder liquid cooled engine which was able to provide 2,200 hp at 16,404 ft (5,000 m) but, due to the start of Operation Barbarossa, Germany was unable to export machinery and tools needed to manufacture the Nu engine. Unfortunately for Takahashi, this turn of events would prevent his design from being completed. As a result of this, Takahashi fell out with the Kōkū Hombu and Kiro Honjo would take over the M-60 project. This time, Honjo followed the Kōkū Hombu’s suggestion and used two engines instead of his idea of four. Under Honjo’s lead, the Taizan’s power plant was changed to two 18 cylinder Mitsubishi Ha-42-11 engines capable of generating 2,000 hp each. It was also seen that Honjo’s design was less aerodynamic than Takahashi’s due to the weaker engines and heavier armament.

On October 31st of 1942, an evaluation was conducted on the work done so far, and a performance estimation gave the Taizan a range of 3,454 mi (5,559 km) and a speed of 332 mph (518 km/h) at 16,404 mi (5,000 m). Falling short of the original 16-shi specification, Mitsubishi scrambled to make adjustments but further revised estimates stated that the design didn’t see any improvements, and actually saw some deterioration. By the time the Taizan’s design was completed in late 1942 and ready for construction of a wooden mockup, a new 17-shi specification was released calling for a new bomber design. Kawanishi took up the design and created the K-100 bomber project. Seeing promise and a better alternative to the Taizan, the Kōkū Hombu ordered all work on the Taizan to be halted until the K-100 could be completed and evaluated. Kawanishi completed initial work on the K-100 and a comparison was made between K-100 and Taizan in the summer of 1943. The Taizan’s range differed significantly from the proposed normal range from 2,302 mi (3,705 km) to 1,726 mi (2,778 km). Due to the significant range reduction, the Kōkū Hombu stopped supporting the Taizan. With no more interest and reason to develop the Taizan, Mitsubishi would finally shelve the project and stop all work on it.

Design

From an exterior aesthetic point of view, the Taizan bears a striking resemblance to the German Heinkel He 177. The nose of the Taizan was rounded and glazed over, a new design not in use by any Japanese bombers at the time. The wings of the Taizan were mounted mid fuselage, and were to be constructed out of metal. Fabrics, however, were to be used for the cover of the Taizan’s ailerons and rudder.

Ordinance wise, the Taizan was to carry a maximum bomb load of 1,764 lbs (800 kg). The defensive armament underwent several changes. Takahashi’s Taizan design was to be armed with two 20mm Type 99 Mk.2 cannons and two 7.7mm Type 97 machine guns. Honjo’s initial design would carry two 20mm Type 99 Mk.2 cannons, two 13mm Type 2 machine guns and two 7.92mm Type 1 machine guns. Later on, the armament finalized at two 20mm Type 99 Mk.2 cannons and six 13mm Type 2 machine guns. There would have been one Type 99 Mk.2 in the nose and one in the tail. There would have been two Type 2 machine guns in the forward upper fuselage turret, two in the rear fuselage turret and two in ventral position, firing rearwards.

Operators

  • Empire of Japan – The Taizan would have been operated by the Imperial Japanese Navy Air Service.

 

Mitsubishi G7M1 “Taizan” *

*Estimated performance of Mitsubishi’s G7M1 proposal

Wingspan 82 ft / 25 m
Length 65 ft 6 in / 20 m
Height 20 ft / 6.09 m
Engine 2x Mitsubishi Ha-42-11 (2,000 hp)
Power Loading 8.8 lbs/hp / 3.99 kg/hp
Empty Weight 23,368 lbs / 10,600 kg
Usual Weight 35,273 lbs / 16,000 kg
Fuel Capacity 4,497 L / 1,188 US Gallon
Climb Rate 32,808 ft / 10,000 m in 10 minutes
Maximum Speed 344 mph / 544 kmh @ 26246 ft / 5,000 m
Typical Range 1,739 mi / 2,799 km
Maximum Range 4,598 mi / 7,400 km
Crew 7
Defensive Armament 6x 13x64mm Type 2 machine guns

2x 20×101mm Type 99 Mk.2 cannons

Ordnance / Bomb Load 1,764 lb / 800 kg – Maximum

Gallery

 

Artist’s conception of the operational G7M Taizan

Sources

Dyer, E. M. (2013). Japanese secret projects: experimental aircraft of the IJA and IJN 1939-1945. Burgess Hill: Classic.Aircrafts of Imperial Japanese Navy. (n.d.). Retrieved February 06, 2018, from http://zenibo-no-milimania.world.coocan.jp/epljn.htmlImages: Side Profile Views by Ed Jackson – Artbyedo.com

 

Kawasaki Ki-88

 Empire of Japan (1943)
Prototype Fighter Interceptor – 1 Built

The Kawasaki Ki-88 was a fighter interceptor designed in 1942 with the intent of intercepting enemy aircraft heading towards vital military locations. The Ki-88 would never see service, as it was cancelled in 1943 after a mockup and partial prototype were constructed. Although considered by many to be the Japanese copy of the American Bell P-39 Airacobra due to the exterior aesthetic similarities, this is only speculation.

History

The origins of the Kawasaki Ki-88 began in August of 1942 when Tsuchii Takeo, a designer for Kawasaki, responded to a design specification put forward by the Imperial Japanese Army Air Service (IJAAS). The IJAAS determined that they needed an interceptor aircraft that would defend important military assets like airfields, gun emplacements, and others. The specification also stated that the aircraft had to be heavily armed, provide a stable gun platform and be easily flyable by new pilots.

Takeo began work on the Ki-88 and chose to use a 37mm Ho-203 cannon as the plane’s primary armament, with two 20mm Ho-5 cannons to complement the Ho-203. The placement of the guns prompted Takeo to place the engine behind the cockpit. Many sources state that this was done to copy the American Bell P-39 Airacobra, but that claim is debated. The P-39 Airacobra was in service at the time the Ki-88 was developed, but saw limited service with the United States. It did however, see service during the Battle of Guadalcanal. The Japanese were certainly aware of its existence and possibly captured an example of the P-39. If they did indeed capture an example, Takeo could have simply copied the gun and engine placement. It is important to note that such a “rear-engine” fighter configuration was a rarity in plane design at the time. Another common theory is that Takeo came to the same conclusion as H.M Poyer (designer of the P-39) did during the planning phase and designed the plane without copying the P-39. Other than the engine and gun placement, the two planes are quite dissimilar.

Takeo completed the Ki-88’s design in June of 1943. A full scale mockup and prototype were in the works in mid/late 1943, and estimated that the prototype would be completed in October of 1943. However, after the mockup and plans were inspected by representatives of the IJAAS, it was concluded that the Ki-88 had no real improvements over other designs of the time, and the top speed was only slightly better than the Kawasaki Ki-61 after calculations. The IJAAS immediately lost interest and ordered Kawasaki to cease all work on it.

Design

The Ki-88 was a single seater, single engine fighter powered by a Kawasaki Ha-140 engine producing 1,500hp while driving a propeller using an extension shaft. The radiator was placed under the cockpit at the bottom of the fuselage. There was an air intake placed beneath the fuselage on the left to provide cooling for the supercharger in the Ha-140.

The Ki-88 used a conventional landing gear, in which the main wheels could be retracted into the wings while the tail wheel stayed fixed. There was a fuel tank in each of the wings, beside the landing gear wells.

The size of the Ho-203 canon prevented Takeo from placing the engine into the nose which led him to place it behind the pilot’s cockpit, much like the American P-39 Airacobra. Moving the engine to the back of the cockpit was a smart move, as it theoretically would have made the plane a more stable gun platform. Under the Ho 203, on both sides of the nose, there were two 20mm Ho-5 cannons.

Operator(s)

  • Empire of Japan – The Ki-88 was supposed to have been operated by the Imperial Japanese Army Air Service, but never did so due to the design being deemed as inferior to the Ki-61 and was thus cancelled.

Kawasaki Ki-88*

*Estimated Performance

Wingspan 40.6 ft / 12.37 m
Length 33.4 ft / 10.18 m
Height 13.6 ft / 4.14 m
Wing Area 8,598 ft² / 27.49 m²
Engine 1x Kawasaki Ha-140 (1,500hp)
Empty Weight 6,503 lbs / 2,949 kg
Loaded Weight 8,598 lbs / 3,899 kg
Climb Rate 6 minutes & 30 seconds to 16,404ft (5,000m)
Maximum Speed 373 mph / 600 kph at 19,685ft (6,000m)
Range 745 mi / 1,198 km
Maximum Service Ceiling 36,089 ft / 11,000 m
Crew 1x Pilot
Armament 1x 37mm Ho-203

2x 20mm Ho-5

Gallery

 

Sources

Performance. Report No. 19b(4), USSBS Index Section 2 (Tech. No. 19b(4)). (n.d.)., Pacific Survey Reports and Supporting Records 1928-1947 Kawasaki Aircraft Industries Company, Ltd. (Kagamigahara, Gifu plant), Dyer, Edwin M. Japanese Secret Projects: Experimental Aircraft of the IJA and IJN 1939-1945. Classic, 2013.Francillon. (1987). Japanese aircraft of the Pacific war. Annapolis, Md: Naval Institute Press., Images: Side Profile Views by Ed Jackson – Artbyedo.com

 

Tachikawa-Kokusai Ta-Gō

 Empire of Japan (1945)
Prototype Special Attack Aircraft – 3 Built

The Ta-Gō was an attempt at creating an easily made and cheap kamikaze aircraft in anticipation of Operation Downfall and Operation Olympic. The plane would have been used by special “shinpū” (kamikaze) units to ram advancing Allied tanks, infantry and boats. Fortunately for the Allies, the Ta-Gō project was cancelled once the Empire of Japan capitulated.

History

The concept of the Ta-Gō came in late 1944, when Japan was on its heels after losing the majority of its territories to the Allies. With the recent loss of Guam, Okinawa, Iwo Jima, and other islands, Japan was convinced that the American invasion of the Japanese mainland was inevitable. By 1945, Japanese factories and industries suffered from constant bombings by the USAAF. This led to the deprivation of much needed materials to produce planes and tanks. Because of this, much of the already existing aircrafts were designed to be built with wood. (Example: Ki-106 from Ki-84, D3Y from D3A). Even then, Japan’s industry could barely produce such planes due to the situation of the war.

Watching his country’s resources slowly depleting and the rapid advance of the Allies, IJA Captain Yoshiyuka Mizuyama wanted to make a difference. He wanted to design a simple, cheap and easily producible plane requiring minimum materials for designated kamikaze units. If the Ta-Gō was mass produced, it could easily fill already depleted kamikaze units, and would make kamikaze attacks more popular. Once Mizuyama finished designing the plane, he went to Tachikawa Hikōki Kabushiki Kaisha (Tachikawa Aircraft Company) and submitted his design. His design was however rejected because Tachikawa Hikōki simply could not afford to allocate resources for the Ta-Gō. It was also rejected due to the fact that Mizuyama’s design was not officially approved by the state.

Determined to initiate his project, Mizuyama looked around the city of Tachikawa until he discovered a small woodwork shop. He rented the shop and began constructing his first prototype with the help of his men. Around February of 1945, Tachikawa was firebombed by the USAAF. The workshop was completely destroyed along with the sole prototype. Still determined to initiate the project despite the major setback, Mizuyama approached Nippon Kokusai Kogyo K.K (Japanese International Aviation Industries Ltd) to continue his project. Luckily for him, Kokusai accepted his project. Since Kokousai accepted the project, they asked that Mizuyama redesign certain parts of the plane to so that it would require even less materials and manpower. The Kokusai design’s dimensions was significantly scaled down compared to Mizuyama’s original design and was simpler altogether.

Now satisfied that his work was accepted, he began building the new model of the Ta-Gō with help from Kokusai. The prototype was completed around the middle of June, and was test flown for the first time on June 25th, 1945 with an experienced pilot from Kokusai in the cockpit. The test pilot expressed obvious handling concerns and gave helpful tips to the designers. As a result, the Ta-Gō participated in more test flights and was modified on the drawing board. In the end, the blueprints for the production variant were finalized. Unfortunately for Mizuyama and Kokusai, the Empire of Japan surrendered to the Allies in August of 1945, and the Ta-Gō never entered production. Interestingly enough, the Allies discovered two variants for the Ta-Gō named “Gi-Gō” and “Tsu-Gō” after Kokusai surrendered all their documents. However, there is no known information on them today.

Tachikawa, funnily enough, took on the project too after the Kokusai prototype was completed and authorized by the Gunjushō (Ministry of Munitions) despite them rejecting the project earlier. Once the American Occupation forces arrived in Japan, they found the Tachikawa Ta-Gō incomplete. Once the Ta-Gō was accepted, it was given the designation Ki-128. It is not confirmed whether the designation was for the Kokusai or Tachikawa variant or both.

Design

The Ta-Gō was a single seated kamikaze plane made mostly out of plywood, fabric, and wood lathes. The original Ta-Gō design used wood lathes for the fuselage and structure, and used plywood and fabric for the outer skin and control surfaces. The pilot’s compartment featured a simple acrylic glass. The landing gear was fixed, meaning they couldn’t be retracted. It featured a Hitachi Ha-13 Ko 9-cylinder radial engine that produced 450hp, with thin steel sheets as the engine cowling. The only armament it could carry was a 500kg bomb, which cannot be released. Other than these details, little is known about the original Ta-Gō as hardly any evidence exists.

The refined design for Kokusai made the Ta-Gō much smaller than its original size. Due to this, the plane could no longer house the Hitachi Ha-13 Ko, and was replaced by the Hitachi Ha-47 11 producing 110hp instead. Because of the severe engine power decrease, the 500kg bomb load had to be changed to 100kg. Another change from the original design was the cockpit was open topped. The only thing that covers the pilot is a simple acrylic glass pane that shields from the wind. As for the engine, it was protected by an angular wooden cowling. The engine was paired with a two-blade fixed pitch wooden propeller. The engine mount was made of metal, with the fuel tank placed on top of the engine, thus using a gravity feed system. In between the acrylic glass pane and the fuel tank, there was an oil cooler. As for cockpit instruments, only the very basic and important ones were kept. Such instruments used were a compass, speedometer, altimeter, and engine-related gauges such as fuel and oil. The fuselage was also boxier than the original design. This design feature was extremely simple to manufacture, but was very un-aerodynamic.

The fuselage and structure was made with wooden spars and plywood, much like the original Ta-Gō. The wings were rectangular shaped, and were hinged near the landing gear, which allowed the the wings to fold upwards. The reason why the wings could be folded was because the Ta-Gō was suppose to be hidden in caves and take up less space in the factory line. The rudder and elevator of the Ta-Gō were both rectangular shaped. As for the landing gear, it was made out of steel tubing and paired with rubber wheels. Each landing gear was supported by a metal strut.

Variants

  • Original Ta-Gō: The original Ta-Gō was powered by a Hitachi Ha-13 Ko (450hp) and could carry a 500kg bomb. It was almost completed before being destroyed in a bombing raid. Only one photo of the original prototype is known to have existed.
  • Revised Ta-Gō:The revised Ta-Gō design featured a smaller airframe to save the factories effort and materials. As a result of this modification, the engine had to be changed to a Hitachi Ha-47 11 (110hp) and the bomb load was reduced to 100kg. Two of these were made. One was completed by Kokusai, test flown and evaluated while the other one by Tachikawa was incomplete.
  • Gi-Gō: The Gi-Gō was a late war development of the Ta-Gō. There is no information known about it to this date. The project was commenced by Kokusai.
  • Tsu-Gō: Like the Gi-Gō, the Tsu-Gō was developed very late in the war. No information about it has been discovered to this date. The project was commenced by Kokusai.

Operators

  • Empire of Japan – The Ta-Gō would have been used by special kamikaze units in both the army and navy.

Ta-Gō (Revised Version) 

Wingspan  8.90m | 29.2ft
Length  7.40m | 24.3ft
Height  3.87m | 12.7ft
Wing Area  5.10m² | 54.9ft²
Engine Hitachi Ha-47 11 (110hp)
Take-Off Weight  565.5kg | 1,290lbs
Empty Weight  345.5kg | 761lbs
Maximum Speed  195km/h | 121mph
Cruising Speed  179km/h | 111mph
Range  150km | 93 miles
Maximum Service Ceiling  4,600m | 15,091ft
Crew  1 (pilot)
Armament 1x 100kg bomb

Gallery

The never completed first Tachikawa prototype
Artist Interpretation of a completed first Tachikawa prototype

Sources

Dyer, E. (2009). Japanese Secret Projects : Experimental Aircraft of the IJA and IJN 1939-1945: Ian Allan Publishing.
Kokusai Ta-Gō. (n.d.). Retrieved August 06, 2017
Ta-Gō. (n.d.). Retrieved August 06, 2017
Beechy, Robert. “Imperial Japanese Army Air Service Aircraft Code Names & Designations.” Japanese Military Aircraft Designations. N.p., n.d. Web. 06 Aug. 2017.