Categories
WW2 Japanese Prototypes

Type 5 Ho-To

Imperial Japanese Army Empire of Japan (1945)
Self-Propelled Gun – 1 Prototype Built

During the Second World War, the Japanese tank industry was mainly focused on developing light tank designs. These were cheap, robust, and had a very simple construction. On the other hand, their armor and armament were rather weak. These could do very little even against Allied light tanks. In order to somewhat resolve this issue, the Japanese would introduce, albeit in small numbers, a series of modified vehicles equipped with weapons of various calibers. While some of these would actually even see combat, others remained only at the prototype stage. This was the case with the unusual Type 95 modification named Type 5 Ho-To.

The only known photograph of the unusual Type 5 Ho-To self-propelled artillery. Source: R. C. Potter Ordnance Technical Intelligence Report No 10

History 

The Japanese tank designs developed prior to and during the Second World War had a rather simple construction, being lightly armored and armed. Given the terrain that these vehicles were intended to operate in, ranging from the vast mountainous terrain of Asia to the countless islands of the Pacific, these proved perfect for the task in the first years of the war. While the defending Allies may have had superior designs, the Japanese used their small weight and mobility to outpace the enemy, often surprising them.

The most produced and probably most successful light tank in the Japanese during the early offensive actions was the Type 95 Ha-Go. With some 2,269 being built (the production numbers differ significantly depending on the source), Type 95 was a relatively common Japanese tank that saw most of its service in the Pacific and Southeast Asia. Initially, it was quite successful against the enemy, but as the Allies began introducing new modern equipment, such as the M3 Light Tanks and later M4 Shermans, the Type 95 became obsolete. With its light armament of a 37 mm gun and armor of up to 12 mm, it could do little against the enemy armor and most ended their service life in futile kamikaze attacks or as static bunkers.

The Type 95 Ha-Go light tank. Source: oruzhie.info

 

The Type 5 Ho-To

The Type 95 and later Type 97 medium tanks’ weakest point was their armament. The short 37 mm and 57 mm and even the dedicated 47 anti-tank guns simply lacked the firepower to seriously threaten the significantly better armored Allied tanks. The Japanese responded by developing small quantities of modified Type 97s, arming them with 75 mm, 105 mm, and even 150 mm guns, mostly mounted in a partly open fighting compartment. Such vehicles were actually used in combat in small numbers and, while not perfect, they proved to be of good use when nothing more suitable was available. These were somewhat similar in appearance to the German Marder series of vehicles.

The Type 4 Ho-Ro self-propelled artillery armed with a 15 cm howitzer was built in small numbers by the Japanese and saw limited combat service. Source: www.mmowg.net

By 1944 and 1945, Japan was hard-pressed on all fronts. Its industry barely kept up with the war demands. Production of armored vehicles was particularly critically affected. While some attempts were made to increase the tank firepower by introducing the Type 3 Chi-Nu medium tank, the production could simply not keep up with its demands for it.

Map of Allied advances against the Japanese-occupied territories from 1943 to 1945. Source: Wiki

Another solution was to simply reuse the available tanks by rearming them with more potent guns. In the last year of the war, the Japanese tried to create a self-propelled version using the Type 95 chassis. This was probably done to reuse the already existing light tank chassis and to keep costs as minimal as possible. They created two rather obscure vehicles, of which very little is known about even to this day. One was the Type 5 Ho-Ru anti-tank version. The second vehicle was a self-propelled version armed with an obsolete 120 mm howitzer designated as Type 5 Ho-Ro. The purpose of the later vehicle is not clear, but it was probably intended to act as a mobile fire support platform. As the 12 cm howitzer also used shape charge rounds, it may also have been intended as an anti-tank vehicle. In appearance, this vehicle shared some resemblance to the previously mentioned Type 4 Ho-Ro self-propelled artillery vehicle.

A very detailed illustration of the Type 5 Ho-To vehicle. Note that, while this illustration has a side vision port, the only known photograph does not have them. It also lacks the elevation mechanism that slightly protruded out of the front armored shield. Source: The Imperial Japanese Tanks, Gun Tanks Self-Propelled Guns

The Type 5 Ho-To’s Design

The precise and even general specifications for this vehicle are almost unknown. Given that it was based on a rather well-documented chassis and with the surviving photograph, some educated guesses can be made.

Hull

The Type 5 Ho-To self-propelled gun would have had more or less a standard hull configuration for most World War Two vehicles. It would have consisted of a fully protected front-mounted transmission, an open-top crew compartment with the main gun in the center, and an engine in the rear, which was likely separated from the crew space by a firewall. The upper glacis retained its two rectangular transmission hatches. The whole vehicle was constructed using mostly riveted armor with slight welding.

Engine

No information is available regarding if the engine was changed or modified in any way. It is highly likely that, in sheer desperation and due to a general lack of resources, the engine was left unchanged. The Type 95 was powered by a 120 hp Mitsubishi 6-cylinder diesel engine. With a weight of 7.4 tonnes, the light tank could reach a top speed of 40 to 45 km/h. While most parts of the upper superstructure and turret were removed, adding the gun with its ammunition would likely have led to the same or even slightly increased weight. Due to the lack of information in the sources, it is difficult to predict its speed or its operational range.

The engine was installed in the rear of the vehicle, slightly off to the right. Its exhaust protruded from the engine bay’s right, bent at a right angle, and was then fixed to the right rear fender. The transmission was located at the front of the vehicle, along with the drive wheels. This meant that a prop shaft extended through the crew compartment, protected by a simple hood.

Suspension and Running Gear

The Type 5 Ho-To utilized an unchanged Type 95 suspension. It was a bell-crank suspension, which consisted of bogies mounted on arms that were connected to a long helical compression spring placed horizontally on the sides of the hull. The spring was protected by a long segment of piping, riveted to the hull side. The bogies pushed against each other via this spring when passing over terrain, allowing them to actuate. It had four road wheels, with two large wheels per bogie. There were advantages to the bell crank system. There were two return rollers, one above each bogie, and an idler wheel at the rear.

The Type 95 and most other modern Japanese tanks employed a simple bell-crank suspension. While not perfect, it was easy to produce and maintain. Source: oruzhie.info

Superstructure

The original Type 95 superstructure, along with the turret, was removed and replaced with a new open-top superstructure of a quite simple design. The new superstructure consisted of simple angled plates which appear to have been welded to each other. There are a few bolts noticeable on the front plate which also indicate that it was connected to some form of a frame behind it. The front plate had a large opening in the middle for the gun. It appears that, due to limited space inside the vehicle, part of the main gun elevation cradle protruded out of this protective shield. There was also an observation hatch for the driver located in the right bottom corner. Lastly, on the top left, is what appears to be a small opening, possibly used for the gun sight.

The front sides were protected by two trapezoidal-shaped plates. Behind them were the partially protected sides. It is likely that this was done to reduce weight but also help with loading additional spare rounds. No top nor rear armor was provided for the crew. This left them quite exposed to enemy return fire and shrapnel.

Front view of a miniature model of a Type 5 Ho-To. Source: live.warthunder.com
Surprisingly, the side armor plate was almost cut off in half. This would leave the crew dangerously exposed to enemy fire from the sides. Also, note the large ammunition box located on top of the engine compartment. Source: ive.warthunder.com
In comparison, the Type 4 Ho-Ro, while a similar design, had fully raised side armor. It too was provided with an ammunition box placed above the engine compartment. Even though a somewhat larger vehicle, it too suffered from a rather cramped crew compartment despite being open to the rear. Source: www.mmowg.net

Armor Protection

The original Type 95 was only lightly protected, with the armor thickness ranging from 6 to 12 mm. On the lower hull, the upper glacis armor plate thickness was 9 mm at a 72° angle, the lower front was 12 mm placed at an 18° angle, and the sides were 12 mm. The armor of the new superstructure was only 8 mm thick, which would offer only limited protection from small arms fire.

Armament

The main armament of this vehicle consisted of one 12 cm Type 38 field howitzer.  This weapon dated back to World War One and was developed based on the German Krupp L/12 howitzer. Like many artillery pieces of that period, it was provided with a screw breech lock and used a hydro spring recoil with a recuperator, which had tapered grooves.

The 12 cm howitzer used two-piece ammunition, with the cartridge and the powder propellant being separated. It could fire high-explosive, armor-piercing high-explosive, and smoke ammunition. While it would be relegated to second-line duties due to its obsolescence, the Japanese developed shape-charged ammunition for it that could penetrate some 140 mm of armor.

Given its age, it is not surprising that its overall performance was outdated by 1940s’ standards. The muzzle velocity was only 290 m/s, which gave it a maximum firing range of a meager 5,670 m. It had an elevation of -5 to +43 and a traverse of only 2°. Its total weight was 1,260 kg.

12 cm Type 38 field howitzer side view. Source: L. Ness Rikugun Guide To Japanese Ground Forces 1937-1945

There is no information about the ammunition load. Given the generally small size of the vehicle combined with two-part ammunition, this would be quite limited, down to possibly only a few rounds. The spare ammunition was stored in a box placed above the engine compartment.

Crew

Even the crew number is unknown. Given the fact that the Type 95’s interior only had room for two crew members (plus the commander in the turret), it is highly likely that this would also have been applied to this vehicle. This meant that there was only room for the driver and the commander. This would have meant that the commander would have had the additional task of operating the gun. The driver, positioned on the left side of the vehicle, would have to act as a loader. This would greatly affect this vehicle’s overall performance. For example, prior to the engagement, the driver would have to exit his position and go back to the rear to take ammunition from the ammunition box, leaving the vehicle completely immobile and easy prey.

An alternative would be that other crew members, such as a dedicated loader, could have traveled with a separate vehicle also carrying extra ammunition.

The Type 95’s small size is obvious here, where two Soviet soldiers examine a captured vehicle. Source: oruzhie.info

The fate of the Type 5 Ho-To

Almost nothing is known about this vehicle in secondary sources. What is known is that at least one vehicle was built and probably tested. How it performed, unfortunately, is unknown. It was either a failure as a design or its further development and possible production were stopped by the end of the war. The final fate of this vehicle is not known, but it was likely scrapped at some point.

Conclusion

The Type 5 Ho-To, at first glance, may have been seen as a cheap modification that could have been done rather easily from available resources, such as the Type 95 chassis and 12 cm howitzer.  In reality, the whole Type 5 Ho-To concept was flawed in many ways. It would have been quite cramped with limited available space inside it. Its main armament would likely have a limited traverse and elevation firing arc. This would have greatly limited its effectiveness in combat but also forced it to constantly change position, possibly causing significant stress on the whole chassis assembly. If the light chassis could effectively sustain the 12 cm gun’s firing recoil without any damage is unknown.

Type 5 Ho-To Illustration made by Godzila

Type 5 Ho-To specifications

Tank Dimensions Length 4.38 m, Width 2.07 m,
Total weight 2.9 tonnes
Crew 2 (driver and commander)
Propulsion 120 hp Mitsubishi 6-cylinder diesel engine
Armament 12 cm Type 38 howitzer
Armor 6-12 mm

 

Sources

Categories
WW2 Japanese Prototypes

Type 5 Ho-Ru

Imperial Japanese Army Empire of Japan (1945)
Self-propelled Anti-tank Gun – Possibly 1 Prototype Built

During the Second World War, the Japanese tank industry was mainly focused on developing light tank designs. These were cheap, robust, and had a very simple construction. While they performed well in the first years of the war, the Japanese failed to properly respond to the increase of armor protection of the tanks of their enemies. The Japanese would introduce the much improved 47 mm anti-tank gun, which offered a better chance of knocking out enemy armor. It was this weapon that was used to arm an obscure and generally unknown project which was initiated in early 1945, the Type 5 Ho-Ru anti-tank vehicle, which was based on the Type 95 Ha-Go chassis.

A visual illustration of how the Type 5 Ho-Ru may have looked like. Source: ww2f.com-3

History 

The Japanese tank designs developed prior to and during the Second World War had a rather simple construction, being lightly armored and armed. Given the terrain that these vehicles were intended to operate in, ranging from the vast mountainous terrain of Asia to the countless islands of the Pacific, these proved perfect for the task in the first years of the war. While the defending Allies may have had superior designs, the Japanese used their small weight and mobility to outpace the enemy, often surprising them, as demonstrated by the fall of Singapore.

Map of the Japanese expansion by 1942. Some of these offensive operations also included the use of parachute units, albeit to a limited extent. Source: Pinterest

The most produced and probably most successful light tank in the Japanese Army during the early offensive actions was the Type 95 Ha-Go. With some 2,269 being built (the production numbers differ significantly depending on the source), Type 95 was a relatively common Japanese tank that saw most of its service in the Pacific and Southeast Asia. Initially, it was pretty successful against the enemy, but as the Allies began introducing new modern equipment, such as the M3 Light Tanks and later M4 Shermans, the Type 95 became obsolete. With its light armament of a 37 mm gun and armor of up to 12 mm, it could do little against the enemy armor and most ended their service life in futile kamikaze attacks or as static bunkers.

The Type 95 Ha-Go light tank. Source: oruzhie.info

The Type 5 Ho-Ru

The Type 95 and later improved Type 97 medium tanks’ weakest point was their armament. The short 37 mm and 57 mm simply lacked the firepower to seriously threaten the significantly better armored Allied tanks. This became quite apparent after the border conflicts with the Soviet Union, especially at the battle at Khalkhin Gol in 1939. Based on this experience, the Japanese initiated a new program to improve their anti-tank guns. This would lead to the creation of the 47 mm Type 1 anti-tank gun, which entered service in 1942.  One of the first tanks to be armed with this gun was the Type 97 Chi-Ha, which replaced its older 57 mm guns in a new turret. While not perfect, the 47 mm Type 1 would become the most used (but still in relatively small numbers) Japanese anti-tank gun during the war.

The Type 97 Chi-Ha tank received a new turret armed with a 47 mm gun. While its anti-tank performance was increased, it was still barely enough to deal with the Allied tanks. Source: ww2f.com

The shortcomings of the 47 mm caliber rounds quickly became apparent to the Japanese, who initiated the development of a series of vehicles armed with 75 and 100 mm guns. These were based on modified Type 97 chassis by adding a new open fighting compartment. While primarily designed as mobile artillery, these vehicles could be still used in anti-tank combat. Given that they were not fully protected, they were quite vulnerable to enemy return fire. The Japanese response to this was a fully protected 75 mm armed Type 3 Gun Tank Ho-Ni III. Only slightly more than 30 such vehicles were ever built and used for protecting the main Japanese islands.

The Japanese Type 1 Ho-Ni was armed with a 75 mm gun placed in a partially enclosed crew compartment. Source: http://ww2f.com/threads/japanese-tanks-and-armored-vehicles.72238/page-3
The Type 3 Ho-Ni III was similarly armed, but the crews were fully protected. Just over 30 of these were built. Source: ww2f.com

By 1944 and 1945, Japan was hard-pressed on all fronts. Its industry barely kept up with the war demands. Production of armored vehicles was particularly critically affected. While most of the previously mentioned vehicles saw some combat action, their actual production numbers were limited. As new vehicles could not be produced, another solution was to simply reuse the chassis of any available tanks, rearming them with more potent guns. This was rather successfully done by the Germans during the war. In early 1945, the Japanese army began experimenting with this idea. As there was probably plenty of Type 95 Ha-Go chassis available, the Japanese attempted to create a simple and cheap anti-tank vehicle. The Type 95’s superstructure and turret were removed and, in their place, a new simplified superstructure armed with the 47 mm anti-tank gun was placed, creating the Type 5 Ho-Ru anti-tank vehicle. Precisely who initiated this project and who actually built the prototype is currently unknown.

The Type 5 Ho-Ru’s Design

It is important to note here that the Type 5 Ho-Ru is a barely documented vehicle with little to no information about its history. It is so obscure that, today, not a single surviving photograph exists besides rather poor-quality drawings. Given that it was based on a rather well-documented chassis, some educated guesses can be made.

Probably the only rather poor drawing of this vehicle that is known to exist. How precise it is, sadly, can not be known at this point. It does give some insight into the design. Source: Wikipedia

Hull

The Type 5 Ho-Ru anti-tank vehicle would have had a more or less standard hull configuration for most World War Two vehicles. It would have consisted of a fully protected front-mounted transmission, an open-top crew compartment with the main gun in the center, and an engine in the rear, which was likely separated from the crew space by a firewall. The upper glacis retained its two rectangular transmission hatches. The whole vehicle was constructed using mostly riveted armor with slight welding.

Engine

No information is available regarding if the engine was changed or modified in any way. It is highly likely that, in sheer desperation and due to a general lack of resources, the engine was left unchanged. Type 95 was powered by a 120 hp Mitsubishi 6-cylinder diesel engine. With a weight of 7.4 tonnes, the light tank could reach a top speed of 40 to 45 km/h. While most parts of the upper superstructure and turret were removed, adding the gun with its ammunition would likely have led to the same or even slightly increased weight. Due to the lack of information in the sources, it is difficult to predict its speed or its operational range.

Suspension and Running Gear

The Type 5 Ho-Ru utilized an unchanged Type 95 suspension. It was a bell-crank suspension, which consisted of bogies mounted on arms that were connected to a long helical compression spring placed horizontally on the sides of the hull. The spring was protected by a long segment of piping riveted to the hull side. The bogies pushed against each other via this spring when passing over terrain, allowing them to actuate. It had four doubled road wheels, with two large wheels per bogie. There were two return rollers, one above each bogie, and an idler wheel at the rear.

The Type 95 and most other modern Japanese tanks employed a simple bell-crank suspension. While not perfect, it was easy to produce and maintain. Source: oruzhie.info
A side drawing of the Type 5 Ho-Ru, where the original Type 95 suspension can clearly be seen. Also note that it would have been a quite small vehicle that could be easily concealed and camouflaged, perfect for ambush tactics. But its small size would also have greatly hindered the crew’s handling of the main armament and the vehicle itself. Source: I. Moszczanski Type 95 Ha-Go

Superstructure

The original Type 95 superstructure, along with the turret, was removed and replaced with a new partially open-top superstructure of quite a simple design. The new superstructure consisted of simple angled plates which appear to have been welded to each other. The front plate had a large opening for the gun located slightly offset to the left. To the lower right, a driver visor port was located.

A model of the Type 5 Ho-Ru showing the front superstructure armor plate. Note the gun placed on the left side, with the small driver visor port next to it. Source: live.warthunder.com

The side armor plates appear to be slightly angled. These were made using single five-sided plates with a sharp angle at the top. While the original drawing has no small vision slits cut into the side armor plate, some more modern illustrations and models appear to have them. These were generally easy to make, so it is possible that the Type 5 Ho-Ru would have had them. They would have provided the crew with a limited side view without the need to expose themselves out of the vehicle.

Type 5 Ho-Ru modern model side view. Source: live.warthunder.com

While the front part of the top armor was enclosed, if this was the case with the rear part is difficult to know. If it was indeed enclosed, then there would have been at least one or two hatches for the crew to enter or exit the vehicle. It is also possible that it was open-topped. This somewhat makes sense, as the Type 5 Ho-Ru was rather a small vehicle and this would have given the crew more room to operate the gun. In addition, it would have provided necessary ventilation for the exhaust gasses created after firing the gun.  Lastly, it would have also reduced the number of materials needed to build this vehicle to some extent. There were no other side nor top hatches for the crew to exit the vehicle.

Rear view of Type 5 Ho-Ru top superstructure. In this model, the rear top part was left open. If this was the case for the real vehicle is sadly hard to tell. Source: live.warthunder.com

The Type 5 Ho-Ru, to some extent, highly resembled the Italian Semovente L40 da 47/32 anti-tank vehicle. The overall configuration, including the position of the same caliber gun , and the whole superstructure are somewhat similar. Also, the Italian vehicle was developed in response to the desperate need for better-armed vehicles. Of course, the two vehicles are completely unrelated and it is highly likely a case of convergent evolution that they share some similarities. Despite that, the Semovente offers us a glimpse of how the Type 5 Ho-Ru’s construction may have looked.

While obviously different in design, the Semovente L40 da 47/32 shared some similarities with the Type 5 Ho-Ru Source: Semovente L40 Comando Plotone vehicle on the first series hull. Source: FIAT Archives
The Semovente L40 da 47/32 rear view. Source: Pinterest

Armament

The main armament of this vehicle consisted of a 47 mm Type 1 anti-tank gun. It was a modern anti-tank gun and was quite superior to the older Japanese 37 mm anti-tank guns in terms of armor penetration. Other improvements over the old guns included adding a larger gun shield, and using rubber wheels which enabled it to be towed using trucks. This gun was introduced to service in 1942.

The 47 mm Type 1 could fire high-explosive and armor-piercing high-explosive ammunition. When using the armor-piercing rounds, the 47 mm gun could penetrate some 52 mm of armor angled at 0° at a distance of 1 km. The muzzle velocity of this round was 827 m/s. The towed version had an elevation of -10° to +18° and a traverse of 58°. Its total weight was 805 kg. While it could engage older Allied tanks, by the time this weapon became available in sufficient numbers, the Allies had introduced better-armored designs, such as the M4 tanks. The 47 mm Type 1 anti-tank gun could destroy an M4 from the sides at closer ranges but, frontally, could do little against it.

The Type 1 47 mm anti-tank gun was modified to fit into tanks and armed the Type 97 Shinhoto Chi-Ha, Type 1 Chi-He, Type 3 Ka-Chi, and Type 5 Ke-Ho tanks. There is no information about the ammunition load on the Type 5 Ho-Ru, but given the small size, it would probably have been limited.

The towed version of the 47 mm Type 1 gun. Source: www.armedconflicts.com
For installation inside tanks, the 47 mm guns had to be slightly modified. Source: A. M. Tomczyk Japanese Armor vol.10

The Semovente 47/32 was armed with the same caliber gun. The gun was mounted on the left side of the hull, in support that allowed a horizontal traverse for 27° and a vertical traverse from -12° to +20°. Despite being a small vehicle its ammunition load consisted of 70 rounds. This may give some indication of the  Type 5 Ho-Ru it is almost impossible to know precisely.

The Cannone da 47/32 Mod. 1935 on the L40 mount. The bag for the ejected cartridges and the round in the breech can be seen. Source: Ansaldo Archives

Armor Protection

The original Type 95 was only lightly protected, with the armor thickness ranging from 6 to 12 mm. On the lower hull, the upper glacis armor plate thickness was 9 mm at a 72° angle, the lower front was 12 mm placed at an 18° angle, and the sides were 12 mm.  The armor thickness of the Type 5 Ho-Ru new superstructure is unknown. Given that its Type 5 Ho-To cousin, which was developed approximately at the same time, was protected by an 8 mm of armor, it is possible that at least the side armor plate of the Type 5 Ho-Ru would have been the same thickness. Of course, this is just an educated estimation without any actual information to confirm this.

Crew

Even the number of crew numbers is unknown. Given the fact that the Type 95’s interior only had room for two crew members (plus the commander in the turret), it is highly likely that this would also have been applied to this vehicle. This meant that there was only room for the driver and the commander. If this was the case, then the commander would have had the additional task of operating the gun. The driver was positioned on the left side of the vehicle. The driver probably also acted as a loader. As such, the commander/gun operator would have been completely overworked, reducing the performance and effectiveness.

The Type 95’s small size is obvious here, where two Soviet soldiers examine a captured vehicle. Source: oruzhie.info

Here, once again, the Italian Semovente L40 da 47/32 may give a hint on the number of crew members. The dimensions of this vehicle were a length of 3.82 m and a width of 1.92 m. In this small space, the Italians managed to squeeze in three crew members, with the commander/gunner being positioned behind the gun. The loader was just right of him and the driver was in front of the loader.

The Japanese vehicle was slightly larger, with a length of 4.38 m and a width of 2.07 m. In theory, this meant that they too could have used a three-man crew. It is important to note that the Japanese developed this vehicle in early 1945, when shortages of material and men were obvious. It is thus quite possible that they had decided to use two crew members out of a lack of manpower. Once again due to lack of any source, this can not be known for sure.

The Semovente L40 da 47/32 interior with its crew. Despite being a rather small vehicle, it was operated by three crew members. This was far from perfect but, given its limited overall size, unavoidable. In contrast to the Type 5 Ho-Ru, the Italian vehicle was completely open-topped. Source: Pinterest

The Fate of the Type 5 Ho-Ru

This is one of several generally poorly documented Japanese vehicles. The Type 5 Ho-Ru prototype may have been completed by April 1945 and tested during the summer. How accurate this information is, is difficult to know, but highly possible.

What happened after that or the overall performance of this vehicle is sadly unknown. There are two versions of its final fate. One is that the Japanese tested it, but the project went nowhere, either due to a lack of resources to build more or due to some design issues. After this, the Japanese may have scrapped it. The prototype or plans being lost to one of many Allied bombing raids should also not be excluded as a hypothesis.

Alternatively, the prototype was left for the defense of the Japanese ‘home islands’ and then was captured by the Allies. Given the lack of mentions of the Type 5 Ho-Ru in the sources and no surviving pictures, the previous version may seem to be closer to the truth. Once again, due to a general lack of information, it cannot be known for sure.

Conclusion

Given its obscurity, as not even a single picture of it is known to exist, not much can be said about the Type 5 Ho-Ru. On paper, this vehicle offered many advantages. It was cheap, small in size, having a relatively effective gun when engaging enemy tanks from sides, reusing already existing vehicles, and weapons, etc. On the other hand, its small size would lead to a quite cramped interior and the gun itself by this time struggled against Allied armor. It is also unknown if there were any other issues with the design. In the end, due to a lack of proper sources, a precise conclusion could not be made that truly reflects its overall performance.

Type 5 Ho-Ru specifications

Dimensions Length 4.38 m, Width 2.07 m
 Armament 47 mm Type 1  gun
Crew 2 to 3 (Commander and driver possibly even a gunner)
Propulsion 120 hp Mitsubishi 6-cylinder diesel engine
Speed 40 km/h
Armor 6-12 mm

 

Sources

Type 5 Ho-Ru Illustration made by David B.

 

Categories
WW2 Japanese Prototypes

Maeda Ku-6 (So-Ra)

Imperial Japanese Army Empire of Japan (1943)
Experimental Glider Tank – 1 Mock-up Built

While tanks can provide excellent offensive firepower, they can not always be easily transported to where they are needed. In the case of Japan during WW2, this was possible to achieve by using ships to transport them to where they were needed. During the war, the concept of a flying tank was becoming an interesting concept for the Japanese military hierarchy. Transporting tanks via air could potentially offer benefits to the airborne troops, who were often left without proper firepower support. This would lead to the creation of the Maeda Ku-6 tank glider.

The Concept of Airborne Operations

The idea of placing airborne troops behind enemy lines offers many tactical advantages. These can attack weak points and enemy supply lines. This in turn would force the opposing side to redistribute its own forces to deal with this problem. On the other hand, airborne forces often lack proper artillery or armor support, making them somewhat an easy target for well-equipped enemies. Some nation armies responded to this by employing light field artillery or even recoilless guns. Transporting armored vehicles proved a more daring task to implement. Tanks, for example, could not be easily carried inside a transport plane or even parachuted due to their weight. The American and British responded by developing lightly armored and armed light 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 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.

The American M22 Locust light airborne tank. Source: Wiki
Antonov’s project of a flying tank was unsuccessfully tested by the Soviets. Source: Wiki

Airborne Japan

The Japanese began developing simple glider designs for civilian 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 (IJA) began developing new gliders in June 1940. In response to this, the Imperial Japanese Navy (IJN) 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 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 into the enemy’s rear lines. Following the end of this campaign, the Japanese did not use paratrooper units in their primary role. These paratroops formations were instead mainly used as ordinary infantry units.

Japanese paratrooper IJN units had two notable deployments: in the successful Battle of Manado (11th-12th January 1942) on Celebes Island (also known as Sulawesi), and in the Battle of Timor (19th 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 conquest of Sumatra in February 1942.

Map of the Japanese expansion by 1942. Some of these offensive operations also included the use of parachute units, albeit to a limited extent. Source: pinterest

In 1943 attempts were made in order to increase their firepower. 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 generally weakly armed parachute 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 becoming dangerous due to US navy and submarine activities.

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 an especially designed glider. But as Maeda was unable to create a glider that could transport a light tank 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 be used as 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 too few numbers.

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

Name of the Project

According to E. M. Dyer (Japanese Secret Projects Experimental Aircraft of the IJA and IJN 1939-1945), 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 (Fighting Gliders of World War II), 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

Given its experimental nature and the loss of the original documentation, not much is known about the So-Ra light tank.

The wooden mock-up of the Japanese airborne tank project. Source:www.armedconflicts.com

Hull 

Due to its intended use, the So-Ra had to be as light as possible. Its total combat weight was estimated to be around 2.9 tonnes. The overall hull design was likely to have consisted of the rear engine compartment and the front crew compartment.

Suspension

Based on the available picture of the wooden mock-up of the So-Ra, it was to have an unspecified five-road suspension. What kind of suspension would be used is unclear. If the previously mentioned fact was sorely based on a Type 98 light tank then it would be using a  bell-crank suspension which was quite common on Japanese tanks. Its later improved version, the Type 2 Ke-To, used a much-simplified bell crank suspension. To complicate the matter further, author D. Nešić (Naoružanje Drugog Svetsko Rata-Japan) mentions that the tank glider project would use a torsion bar suspension. It would likely have had a front-drive wheel, rear idler, and two return rollers.

Type 2 Ke-To with its slightly different suspension to the Type 98. Source: Wiki

Engine

The So-Ra was to be powered by an air-cooled four-cylinder 50 hp @ 2,400 rpm gasoline engine. Fuel capacity was to be around 150 liters. Thanks to its small weight, the maximum speed with this engine was estimated to be around 42 km/h.

Superstructure and Turret

On top of the hull, a superstructure was placed. Its central part appears to have had a simple box-shaped structure to allow the crew to fit inside the short and small vehicle. The front driver compartment was provided with three large vision ports. This was necessary, as the driver was also the glider pilot, so giving him the best possible view of the surroundings was important. On top of the driver compartment, an escape hatch was likely located. The centrally-positioned turret also appears to have a simple box-shaped design.

Armor

The armor thickness of this tank is unknown, but given its role, it would have been very light. E. M. Dyer mentions that it would have likely not exceeded more than a maximum of 12 mm.

Armament 

Regarding armament, three different configurations were suggested. The first would have been a 37 mm gun. Which precise type is unclear, but given its availability, it was possibly the Type 94 tank gun, as some sources have suggested (E. M. Dyer Japanese Secret Projects Experimental Aircraft of the IJA and IJN 1939-1945). This tank gun was actually a modified 37 mm Type 94 infantry anti-tank gun. It had a muzzle velocity of 575 m/sec, it could penetrate 35 mm of armor at 300 m with Armor Piercing (AP) rounds. The gun could also fire High-Explosive (HE) rounds, although the effect of 37 mm HE was rather minor. A semi-automatic sliding breechblock fed the ammunition. Loading the gun would have been extremely easy to do one-handed, as the cartridges were rather small, at around 13 cm long and 4 cm in diameter.

A close-up view of a dismounted Type 94 37 mm gun. Note the firing pistol grip handle and the shoulder-guard stock. Source: forum.axishistory.com

If this vehicle was truly based on Type 98 or the improved Type 2 Ke-To, the 37 mm Type 1 may have been used. This is basically the same gun but with a longer barrel which offered a better velocity of 797 m/sec. The armor penetration was also increased to 44 mm at ranges of 500 m. Note that these numbers may vary between different sources.

The second variant consisted of a single 7.7 mm or larger caliber machine gun. This would have possibly been the Type 97 7.7 mm heavy ‘tank’ machine gun. This was an air-cooled machine gun, fed from a top-loading magazine, similar to the British Bren gun. This machine gun was actually a Japanese version of the Czech ZB vz 26 machine gun. It was equipped with a stock that was angled off to the right, allowing a gunner to line their eye up with the sight.

 

The Type 97 7.7 mm Heavy ‘tank Machine Gun. Note the top-loading magazine, x1.5 scope, and the armored barrel cover. Source:  ww2f.com

Lastly, a flamethrower was considered a potential armament.  Given the small size of the Ku-6 vehicle, the ignition fuel load for it would have been quite limited.

The ammunition load of either gun or machine gun version is unknown. However, given the cramped space inside the small glider tank, and the need to save weight, this would likely be quite limited.

Crew

The So-Ra 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, the commander, who was also responsible for operating the main armament, was positioned. This small crew would greatly affect the tank’s overall performance. Given the limitation in size and weight, adding more crew members was not possible.

Wing Configuration

The Ku-6 was designed as a tank transporting glider. Due to the loss of the original documents, not much is known about its overall design. Over the years, historians have devised two different designs of how this contraption may have looked based on available information.

According to the first proposals, the tank itself was designed to act as an improvised glider fuselage. The wings and the tail assembly would be attached to it. The tank crews would be provided with wired control wires inside the vehicle. In front of the tank, a towing cable would be added.

In the first version, the wings were to be attached to the So-Ra sides with the tail assembly to the rear. Source: www.armedconflicts.com

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: www.armedconflicts.com

As the tracks would cause huge drag, specially designed sleds would be attached to them during take-off to facilitate an easier take-off. 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. The maximum speed that could be achieved during the flight was 174 km/h.

It is important to note that these are both speculations on behalf of historians, and the actual method of constructing the glider is currently unknown.

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 extra weight was intended to be used instead. The prototype was taken to the sky by a Mitsubishi Ki-21 aircraft. Almost from the start, the Ku-6 proved to have poor overall flight performance. The pilot had a poor view. Lastly, as it was specially designed to carry the So-Ra, its transport capacity for other vehicles was limited. The IJA officials quickly became disinterested in the Ku-6, focusing instead on the Ku-7, which looked more promising. Another aspect that we must take into account was the generally poor state of the Japanese Army in 1945. By this point, it was so battered and depleted that realistically 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: Wiki
The Ku-7 was a more orthodox glider design. While small numbers were built, 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 enemy fighters which, by its construction time, had almost complete air supremacy.

Maeda Ku-6 hypothetical side wing configuration, Illustration made by Godzilla
Proposed version with the top wing construction. Illustration made by Godzilla

Maeda Ku-6 specifications

Tank Dimensions 4.07 x 1.44 x 1.88 m
Total weight 2.9 tonnes
Crew 2 (driver and commander)
Propulsion Four-cylinder 50 [email protected],400 rpm gasoline engine
Armament 37 mm gun or 7.7 machine gun or a flamethrower
Armor Possibly up to 12 mm
Top speed 42 km/h

 

Sources

 

Categories
WW2 Japanese Prototypes

Mitsu-104

Imperial Japanese Army Empire of Japan (Mid 1930s)
Heavy Tank – Prototype/Paper Design

After the First World War, most nations started looking at their armed forces, specifically to how advances in weapons technology affected the way they would and could fight. The Japanese were no exception, especially in armored vehicle development. In many respects, the Japanese Army avoided many of the dead ends that other nations experienced and arguably came closer to getting armored warfare right than any other nation. This was quite likely an accident forced upon the Japanese by circumstances.
One of the few dead ends that the Japanese did encounter, however, was the multi-turreted tank, the Mitsu-104, which was most likely a development of the Type 97 Heavy tank, which was the one heavy tank the Japanese had that went into service.
Schematics of the Mitsu 104 Heavy Medium Tank found in the UK National Archives.

Background

All the information on the Mitsu-104 comes from a British military intelligence dossier on enemy tanks, which was compiled between January 1939 and March 1943. This information was then later passed on to the rest of the Commonwealth and the United States, who included it in their own enemy equipment handbooks that were issued to the armed forces.
The British information came from original Japanese documents, obtained before the Second World War, although no details of where or how these documents were obtained is included in the files. The paper type and size are all identical to the Japanese standards used at the time, both of which were different from the conventions used by the British, all of which implies that the documents are original, and thus credible.
There does appear to have been some confusion within the documents about the exact location of weaponry on the tanks though. This is likely because of some inaccuracies in the Japanese text, which again raises the mystery about where the documents came from. Despite this, the translations includes original, archaic Japanese measurements (which are re-created in the specifications table).
The British documents describe the Mitsu-104 as a ‘Heavy Cruiser’, despite the fact that Japanese documents clearly referred to it as a Heavy.

Drawing of the Mitsu 104 from a Swedish intelligence document. Source

Description

Japan spent a large part of the 1920’s obtaining examples of foreign armored vehicles and concepts. One such example is the A1E1 Independent, which the Japanese obtained plans for, resulting in the Ishi-108 that has been ascribed as being designed/constructed by the Japanese Empire by British documents, although no other evidence of its existence has surfaced. One of the few failures of tank design the Japanese picked up was the idea of multi-turreted tanks. This likely came from their interest in the British A1E1 Independent and the Soviet T-28 tanks.

Multi-turreted tanks are almost universally considered to be a bad idea because they add weight to the tank from items such as gearing and the structure required to mount a turret as well as making the vehicle much harder to command. On a single turret tank, this weight could be used for more armor or bigger guns and engines. Multiple turrets also comprise the armor integrity by having a series of holes in the armor to mount the turrets.

The Mitsu 104 from a 1944 British-issued recognition handbook on Japanese equipment.
This unfortunate trend in design existed in all the Japanese heavy tank projects, apart from the AI-96 from 1936.
One such multi-turreted design was the Mitsubishi 104, which is shortened in the documentation to “Mitsu-104”.
There seems to be no evidence the Mitsu-104 was ever built, unlike the Type 97 Heavy Tank. Design wise, it seems to have been a logical development of the Type 97, looking far more refined and capable, although the exact date of the tank’s design is unknown.
The Mitsu-104 had three slightly conical turrets. The main turret mounted a 75mm low velocity gun possibly based off one of the Japanese field artillery guns of the same calibre. Two sub-turrets were mounted on the front hull, each with a machine gun.

Original Japanese drawings of the Mitsu 104 found in the British National Archives.
There was some confusion about the armament for the tank. A pair of 37mm guns were listed, however, the British were confused as to their location. The Type 97 Heavy tank from 1937 had the option of two 37mm guns or a single 75mm guns mounted in the turret. This is likely because the Japanese considered the heavy tanks for the support of the infantry, and in the Japanese military 37mm guns were called ‘rapid fire infantry guns’. The British documents suggest the Mitsu-104 could have had 37mm guns in the sub-turrets, which certainly look big enough to mount such a weapon. This could, of course, be a translation mistake for the twin guns in the main turret.
The rest of the hull was conventional in its layout with the engine at the rear of the tank. Although the tank is rather wide for its size.
The suspension was the same style of Bell Crank suspension used on most Japanese tanks of the period and indeed lived on until the failed O-I Super Heavy Tank design.


The Mitsu-104 with 37mm main armament.


The Mitsu-104 with 75mm main armament.

Both illustrations are by William ‘Richtor’ Byrd, funded by DeadlyDilemma through our Patreon campaign


United States tank recognition chart showing the Mitsu 104 in the lower left corner.

Conclusion

The design, from the particulars written down, does seem to be over-optimistic in regards to its mobility and speed. This was a common fault with Japanese heavy tank plans, with tanks such as the Ishi-108 and O-I having suspiciously overinflated claims of speed from engines that seem to produce far too little power to propel such masses at such speeds. For example, a 30 ton Sherman tank with a 350hp engine could obtain about 22mph. The Japanese predicted that the same power output would move the 29 ton Mitsu-104 at 30mph. To achieve similar figures, a Sherman needed over 400hp.

3D reconstruction of how the Mitsu 104 might have looked like. Source: Forgotten Tanks and Guns of the 1920s, 1930s and 1940s  by David Lister

The Mitsu 104 being mentioned in the Japanese military forces. Report No. 12-b(11), USSBS Index Section 6.

Mitsu-104 specifications

Designer Mitsubishi
Dimensions (L-W-H) 8.30 x 3.20 x 2.80 m (27.2 x 10.6 x 9.3 ft)
Weight 29 tons (58000 lbs)
Crew 8
Propulsion Water cooled, Mitsubishi 12 Cylinder Petrol engine, delivering 350hp at 2200rpm. Fitted with a 12 volt electrical starter.
Armament A combination of 75mm and 37mm guns, and several machine guns.
Armor 25-30mm (0.98-1.18 in)
Speed 12 Ri (25mph, 40kph)
Gradient 40 degrees
Step 1.20 m (3.11 ft)
Trench Crossing 3.90 meters (12.10 ft)
Fording 1.20 meters (3.11 ft)

Sources

Sensha-manual.blogspot.com
WO 208/1320, UK National Archives in Kew, London
Forgotten Tanks and Guns of the 1920s, 1930s and 1940s  by David Lister
World War II United States recognizition chart
British 1944 Japanese-equipment recognition handbook
Japanese military forces. Report No. 12-b(11), USSBS Index Section 6, https://dl.ndl.go.jp/info:ndljp/pid/4009934/9
https://germandocsinrussia.org
Forgotten Tanks and Guns of the 1920s, 1930s and 1940sForgotten Tanks and Guns of the 1920s, 1930s and 1940s

By David Lister

History forgets. Files are lost and mislaid. But this book seeks to shine a light, offering a collection of cutting edge pieces of historical research detailing some of the most fascinating arms and armament projects from the 1920s to the end of the 1940’s, nearly all of which had previously been lost to history.Included here are records from the UK’s MI10 (the forerunner of GCHQ) which tell the story of the mighty Japanese heavy tanks and their service during the Second World War.

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Categories
WW2 Japanese Prototypes

Type 97 Chi-Ni

Imperial Japanese Army Empire of Japan (1938)
Experimental Medium Tank – 1 Built

Chi-Ha’s Competition

In 1938, the Japanese military began looking for a replacement for the ageing Type 95 Ha-Go light tank. High ranking members of the military had a preference for more lightly armored infantry support vehicles. As such, two medium tank projects were put forward, with specific guidelines set.

These were: a maximum weight 10 tonne, 20mm maximum armour thickness, 3 man crew, maximum speed 27 km/h (17 mph), trench crossing capability of 2200 mm upgraded to 2400mm with a ditching tail and armament consisting of a 57 mm gun and one machine gun.

Development

Under the working name of Medium Tank Project Plan 2, The Type 97 Chi-Ni (試製中戦車 チニ Shisei-chū-sensha chini) was submitted by Osaka Army Arsenal. It was a low cost alternative to its competition, the Type 97 Chi-Ha, made by Mitsubishi Heavy Industries.

The Chi-Ni was envisioned as a smaller, lighter alternative to the Chi-Ha, and was easier and cheaper to produce. The prototype was completed early 1937, taking part in trials against the Chi-Ha soon after.

It featured a number of cost-cutting features. It was of mostly welded construction, Its drive wheels, idler wheels and tracks were the same as those used on the Type 95 Ha-Go. For a time it was tested with the Ha-Go’s suspension, but it was soon apparent that it did not support the longer chassis well enough.

A mock-up of the Chi-Ni hull alongside the Ha-Go. Source: The Koku-Fan, Oct. 1968

Design

Hull

The hull was designed with a streamlined silhouette to protect from shell damage, and was of a monocoque design. Also known as structural skin, monocoque is a French word meaning “single hull” and is a structural system where loads are supported through an object’s outer layers.

A side shot of the Chi-Ni prototype. Source: live.warthunder.com

This method is also used on some early aircraft and in boat building. Because of this, the tank was mainly of a welded construction, an unusual design choice for Japanese tanks of the era, which were mostly riveted onto a skeletal framework. The rear of the hull also featured the somewhat archaic feature of a ditching or “tadpole tail” to help it cross trenches. This was a removable feature.

Though the armor was only 20mm thick, it was extremely well-angled. The driver’s position was encased in a semi-hexagonal box; in front of this was the flat bow, leading to a negatively angled lower glacis.

A rear view of the Chi-Ni, showing the removable ditching tail..

Armament

The main armament consisted of the Type 97 57mm. Its primary ammunition was HE (High-Explosive) shells and HEAT (High-Explosive Anti-Tank) rounds. This was the same gun as found on the initial models of the Chi-Ha. The gun kept the Japanese tradition of excellent depression. In the Chi-Ni’s case, this was negative 15 degrees over the front and left side. Depression over the right and engine deck would have have been slightly limited by at least 5 degrees.

The depression suited the tank’s infantry support role because it was able to fire High Explosive shells at close range on advancing enemy infantry, or down into occupied trenches. Furthermore, like the Chi-Ha, the Chi-Ni’s turret ring was made as large as possible, to allow for any future turret upgrades.

Mobility

The tank shared a similar bell crank suspension to the Ha-Go – this being a near constant of Japanese tank designs of the epoch. The difference was that in the case of the Chi-Ni, at the end of each bogie were 2 small road wheels, making 8 per side.

The forward-mounted drive wheels were powered by a Mitsubishi 135 hp diesel engine that would propel the vehicle to a blistering 27 km/h (17 mph). It was also tested with the 120 hp Mitsubishi A6120VDe air-cooled diesel engine from a Type 95 Ha-Go.

A top-down view of the Chi-Ni showing the engine deck.

Crew

The Chi-Ni was a 3 man vehicle, compared to the 4 of the Chi-Ha. The commander of the vehicle was positioned in the turret, which was offset to the left of the tank. The turret was so small that he also had to act as loader and gunner to the 57mm gun. Directly below and slightly in front of the commander sat the driver. With no room in the turret for a coaxial machine gun, the third crew member sat on the driver’s right who would operate the ball mounted 7.7 × 5.8mm Arisaka Type 97 machine gun. These two crew members would have been relatively well protected from enemy fire.

This image shows just how off-centre the turret is. Source: www.weaponsofwwii.com.

Losing to the Chi-Ha

At the time of its conception, the Chi-Ni was considered the superior tank as it was so much lighter and cheaper to build. However, whilst the Chi-Ni and Chi-Ha trials were in progress, the Marco Polo Bridge Incident occurred on July 7th 1937, marking the start of the Second Sino-Japanese War.

The Chi-Ha undergoing mobility trials. Source: The Koku-Fan, Oct. 1968

Peacetime budgetary limitations evaporated with the outbreak of these hostilities with China. With this, the somewhat more powerful and expensive Type 97 Chi-Ha was accepted for development and service as the Imperial Japanese Army’s new medium tank. It would go on to become one of Japan’s most highly produced tanks.

Only one Chi-Ni prototype was ever built and its fate is unknown. It is likely that it was broken down and recycled with its parts put back into circulation.

Originally Published November 27th 2016


Illustration of the Type 97 Chi-Ni by Andrei ‘Octo10’ Kirushkin, funded by our Patreon Campaign.

Type 97 Chi-Ni

Dimensions 17 ft 3 in x 7 ft 4 in x 7 ft 8 in (5.26 m x 2.33 m x 2.35 m)
Crew 3 (driver, commander, machine-gunner)
Propulsion 135hp Mitsubishi diesel engine
Speed 17 mph (27 km/h)
Armament Type 97 57mm Tank Gun
7.7×58mm Arisaka Type 97 machine gun
Armor 8-25 mm (0.3 – 0.9 in)
Total production 1 Prototype

Sources

Chi-Ni on www.weaponsofwwii.com
Japanese Tank Development
AJ Press, Japanese Armor Vol. 2, Andrzej Tomczyk
Osprey Publishing, New Vanguard #137: Japanese Tanks 1939-45.
Profile Publications Ltd. AFV/Weapons #49: Japanese Medium Tanks, Lt.Gen Tomio Hara.
Bunrin-Do Co. Ltd, The Koku-Fan, October 1968


Categories
WW2 Japanese Prototypes

Type 91 & Type 95 Heavy

Imperial Japanese Army Empire of Japan (1935)
Prototype Heavy Tanks – 4 Built

During 1930s, fears were strong among the most powerful military nations that a coming war would develop along the same lines as WWI. No one wanted another war rife with stalemates, no one moving for months on end due to swamp like terrain, and constant machine gun bombardment. As such, tank designs of the period were heavily set on infantry support, being large, slow moving and bristling with anti-personal weaponry. The era became awash with the fad of multi-turret tank designs, with all of the most powerful countries adopting them in one form or the other.

The A1E1 Independent for the British Empire, the Großtraktor or Neubaufahrzeug for Nazi Germany, and the T-35 of the Soviet Union are prime examples of this design fashion. One might even consider the mobile machine-gun nest that was the United States’ M2 Medium to be part of the group.
Imperial Japan was no exception to the rule, coming up with their own design in 1934. This was the Type 95 Heavy Tank (タイプ95重タンク, Taipu 95-jū tanku).

The Experimental Tank No. 1, Type 87 Chi-I.
The roots of the Type 95 Heavy begin with the first tank the Japanese Military produced independently, the Experimental Tank No.1 (実験タンク番号壱, Jikken tanku bangō wən), also known as the Type 87 Chi-I. This ancestor to all Japanese tanks was built in 1927, and was classed by the Military as a Medium Tank. It didn’t progress further than the prototype phase, however.

The Type 91

The first prototype of this heavy tank was built in 1931 and was designated the Type 91. This was an 18-ton vehicle, powered by a 6-cylinder BMW IV inline engine that ran on gasoline. The engine was likely purchased from Germany. The tank had 3 turrets, a main one in the center armed with a 57 mm (2.24 in) cannon, and 2 secondary forward and rear turrets armed with 6.5 mm (0.26 in) machine guns. It also had an armor 8 – 17 mm thick.
The Prototype vehicle Type 91, undergoing crossing trials
The Prototype vehicle Type 91, undergoing crossing trials. The complicated suspension can be seen here.
A feature carried over from the Type 87 Chi-I was the rather complicated parallelogram suspension system with two pairs of road wheels per leaf-sprung bogie. There were 17 road wheels per side, giving it a total of 34 road wheels. The parallelogram type of suspension is more commonly known as Swing arm suspension, which is mostly used on motorcycles.
The Type 91 proved to be an unsuccessful endeavor, and the project was soon canceled. The lessons learned were passed on to the Type 95.

Type 95 Heavy, Design and Development

Imperial Japan felt that the increasingly powerful Soviet Union could be a potential future enemy. As such, work once more resumed on a heavy tank for the Imperial Japanese Army (IJA) to match the Red Army’s T-35 heavy tank.
The development of the Type 95 Heavy began in 1932, with a prototype not being complete until 1934. The overall structure of the chassis and module layout was much the same as the previous Type 91 prototype. However, it was given significantly thicker armor, thicker than all of Japan’s other tanks of the era. The turret face was 30 mm, with 25 mm on the sides and the rear. The upper plate bore the thickest armor at 35 mm. The sides weren’t lacking either as they were 30mm thick with a further 25mm on the rear of the vehicle.
This amount of armor increased the weight of the vehicle to 26 tons, the heaviest tank Japan had yet built.
The suspension was also altered, with a much simpler form of leaf-spring suspension. The amount of road wheels was drastically reduced, down to 9 a side, giving it a total of 18. This was found to give the same performance, while being much less complicated.

The Type 95 during trials, showing how the suspension operates.


A 3D model of the Type 91 Heavy by Giganaut


Tanks Encyclopedia’s rendition of the Type 91 Heavy by David Bocquelet.
Tanks Encyclopedia’s rendition of the Type 95 Heavy by Jarosław Janas.

Weaponry

Like the legendary samurai of ancient Japan, the Type 95 Heavy would carry 3 weapons into battle. For a Katana, its main weapon mounted in the primary turret, a unique Type 94 7cm tank gun. It’s Wakizashi, a secondary weapon, a Type 94 37mm (3.7cm) cannon mounted in the forward turret. And finally, its Tantō, the third weapon, a 6.5mm machine gun mounted in the rear turret.

The 7cm gun was a short-barreled type, able to fire both Type 92 HE (High-Explosive) shells and Type 95 AP (Armor-Piercing) shells. Further ballistic data is unknown. The Type 94 37mm cannon is the same as equipped on the Type 95 Ha-Go light tank, with average armor penetration 36 mm (1.4 in) at a distance of 275 m.

Fate

The vehicle did go through trials in 1935, and performed well. Production was limited to only 4 vehicles, however, due to logistical and practical reasons. High-speed lighter tanks, more suited to Japanese tank doctrine were starting to come along, such as the Type 95 Ha-Go.
With only 4 Type 95 heavies built by 1934, the project was canceled. It was considered too slow and much too big. Also, it was soon apparent that a multi-turret tank design was a less than practical concept. It is rumored that at least one of the vehicles took part in a parade in Tokyo in 1935. This was part of the Yasukuni Military Expo during which Japan showed many of their newest armored vehicles.

A disarmed Type 95 at the Yasukuni Shrine.
This wouldn’t be the end of the Japanese work on heavy tanks, however. The next generation of such vehicles in Japan would be “Super Heavies”. This would include vehicles such as the O-I Super Heavy Tank.
None of the Type 95s survive today, though one was kept at the Chiba as a training vehicle up to 1945.

Variants

As limited as the production of this vehicle was, Self-Propelled Gun (SPG) variants were conceptualized, with 2 chassis handed over to Mitsubishi Heavy Industries for testing.

These chassis became the bases of the Ji-Ro/Ji-Ro Sha (Left) and the Hi-Ro-Sha (Right). These Tank Destroyer variants were mounted the powerful Type 14 105mm Gun, also known as the “10-cm cannon”. The Hi-Ro Sha was an open top vehicle, with the 105mm gun munted at the front behind a small gun shield. The Ji-Ro/Ji-Ro Sha was a bit more of an extensive modification. A large case-mate was placed on the rear of the tank, with the 105mm mounted inside. While the Hi-Ro did reach the Prototype phase, it is unclear wether the Ji-Ro did as well. No photos of it are known.

The Prototype Hi-Ro/Hi-Ro Sha. While there are a few photos of this vehicle, none seem to remain of the Ji-Ro. Photo: – Radikal.ru

An article by Mark Nash

Type 95 Heavy Specifications

Dimensions (L-W-H) 6.47m x 2.7m x 2.9m (21ft 2in x 8ft 8in x 9ft 5in).
Total weight, battle ready 26 tons
Crew 5 (commander, gunner, loader, driver, forward gunner, rear gunner)
Propulsion BMW IV water-cooled inline six-cylinder gasoline engine
Speed 22 km/h (14 mph)
Armor 12 – 35 mm (0.47 – 1.37 in)
Armament Type 94 7cm Tank Gun, Type 94 37mm Tank gun, x2 6mm machine guns. (1 on the rear of the primary turret, 1 in the rear turret)
Total production 4

Links & Resources

Type 91 & 95 Heavy on IKAZUCHI
The Type 95 Heavy on the Japanese Wikipedia
Osprey Publishing, New Vanguard #137: Japanese Tanks 1939-1945
Delta Publishing, Ground Power #41, Japanese military vehicles of the Second World War

Categories
WW2 Japanese Prototypes

Type 5 Ke-Ho

Imperial Japanese Army Empire of Japan (1944-1945)
Light Tank – 1 Built

Although it had performed well before the outbreak of the Second World War, and during it’s early stages, the Type 95 Ha-Go was showing it’s age by 1942. It simply didn’t stand a chance against the increasingly powerful tanks being fielded by the Americans in the Pacific, and later, the Soviets in Northern Manchuria.

Between 1942 and 1943, attempts had been made to replace it with a new light tank. This resulted in the Type 98 Ke-Ni and Type 2 Ke-To, respectively. However, these projects failed to fully materialize with only 104 Ke-Ni and 34 Ke-Tos built by the end of the war.

Following this, the IJA decided to try again and work started on the Type 5 Ke-Ho (五式軽戦車 ケホ Go-Shiki Keisensha Keho). It was the last light tank designed by the Imperial Japanese Army (IJA).

A scale drawing of the Ke-Ho. Source: ftr.wot-news.com)

Development

The Ke-To experimented with a slightly better main armament in the form of Type 1 37 mm (1.46 in) gun. This offered a much-needed improvement over the Type 94 37 mm (1.46 in) used on the Ha-Go. Though a step in the right direction, this weapon still was not enough to combat the M4 at any angle. The quest to mount the new Type 1 47mm tank gun on a fast, mobile chassis began in 1942. Up till then, the Ha-Go had performed well against American M3 Light tanks, but began to suffer as more heavily armored tanks began to appear such as the M5 Stuart and the larger M4 medium tank. The Ha-Go’s last successful engagement was against Ameican forces on the Bataan Peninsula in December 1941. A force equipped with M3 Stuart Light tanks.

It was projected that this new light tank would have a 4-man crew. This consisted of the Driver (front right hull), bow gunner (front left hull), the Commander who also acted as loader (right turret) and the gunner (left turret).

Design

Hull

The Hull of the Ke-Ho was based on an enlarged Ke-Ni/Ke-To chassis. It utilized a miniaturized bell-crank suspension, based on that of the Chi-Ha/Chi-He with 6 road-wheels per-side, 3 return rollers and a rear mounted idler wheel. The bell-crank suspension consists of bogies mounted on arms, which in turn are connected to a long spring on the side of the hull. The bogies push against each other when passing over terrain, allowing the bogies to actuate. The Ke-Ho was powered by a 150hp Type 100 air-cooled diesel engine. Despite its heavier weight, the Ke-Ho would still be able to travel at a top speed of 50-55 km/h (31 – 34 mph). Like the majority of Second World War Japanese armor, the engine was placed in the rear with the transmission and drive sprockets at the front.

Armament

The turret planned for use on the Ke-Ho was based on the original Chi-He design, which in turn was based on the Chi-Ha Shinhoto’s. It had a long, square rear with a rounded turret face. There was a cupola on the right side of the roof with a two-part hatch and vision periscopes for the commander. The tank would be armed with the Type 1 47mm tank gun, as used on the Chi-Ha Shinhoto and initial models of the Chi-He. This gun had a muzzle velocity of 840 m/s (2,723 ft/s) and could penetrate a maximum of 55 mm (2.2 in) at 100 meters (328 feet). It was equipped with both Armor-Piercing High-Explosive (APHE) rounds and High-Explosive (HE) rounds. Although this gun was a huge improvement over the 37mm of the Ha-Go, it was still not enough to combat the front of an M4. It is likely that if the Ke-Ho made it to combat, it would have to exploit the same flanking, close quarters ambushes utilized by Shinhoto Chi-Has. Although the maneuverabiity of the Ke-Ho would of made that task much easier.

The Type 1 47mm Tank Gun. Photo: The Koku-Fan, Oct. ’68

Secondary armament consisted of two Type 97 7.7mm machine guns. One of these was located in a ball mount on the front left of the hull, operated by the bow-gunner. The other was located in the right-rear corner of the turret bustle, operated by the loader. Either of these guns could be dismounted and placed atop a mount next to the commander’s cupola.

Armor

One of the major shortcomings of the Ha-Go which designers sought to address was the fact that with a maximum of just 12mm (.47 in) thick armor, a .50 cal (12.7 mm) machine gun could effectively knock one out. The Type 98 Ke-Ni and Type 2 Ke-To had somewhat of an armor upgrade, with a maximum of 16mm (.62 in). However, this was still not enough to reliably counter .50 cal rounds. As such the, Ke-Ho would have an even greater increase to armor thickness, being at least 20 to 50 mm (.78 in – 1.9 in) thick, more than enough to stop a .50 caliber round.

Variants

Ku-Se SPG

A planned variant of the Ke-Ho was the Ku-Se (自走砲 Jisōhō クーセ) self-propelled gun/tank destroyer. It was to be armed with a Short Type 99 75 mm mountain gun, in a similar open case mate to the planned Ho-Ni and Ho-Ro SPGs.

Drawing of the Ku-Se variant. Source: ftr.wot-news.com

Fate

In 1942, a prototype vehicle was built, and the project was canceled soon after. As with most new tank designs the Japanese came up with, it was low on the list of importance. Resources and construction efforts were instead being focused on warships and warplanes. Mass production was approved in 1945 however, but this was of course too late and the one prototype remained the only one built. This also meant that the Ku-Se variant never left the drawing board.

A post-war drawing of the Ke-Ho. Source: – N/A

What happened to the prototype is unknown. It was likely taken back to the USA for analysis and later broken down.



Illustration of the Type 5 Ke-Ho based on available drawings. Note the miniature bell-crank suspension and the early Chi-He turret armed with the Type 1 47mm gun. The placement of a jack and pioneer tools on the left rear fender is speculative. However, it is also based on the known placement of such items on other Japanese tanks of the era. This Illustration was produced by Brian Gaydos, funded by our Patreon Campaign.

Known Specifications

Dimensions 4.38 meters long
Weight 9 tonnes
Crew 4 (driver, gunner, commander, bow gunner)
Propulsion 150hp Type 100 Air-Cooled Diesel
Speed (road) 50 km/h (31 mph)
Armament Type 1 47mm Tank Gun
2x Type 97 7.7 mm machine guns
Armor 20 mm – 50 mm (0.78 – 1.9 in)
Total production 1 Prototype

Sources

Osprey Publishing, New Vanguard #137: Japanese Tanks 1939-1945
Profile Publications Ltd. AFV/Weapons #49: Japanese Medium Tanks, Lt.Gen Tomio Hara.
Profile Publications Ltd. AFV/Weapons #54: Japanese Combat Cars, Light Tanks and Tankettes, Lt.Gen Tomio Hara
Bunrin-Do Co. Ltd, The Koku-Fan, October 1968