Type 5 Ho-Ru

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.

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.

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 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 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.

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.

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.

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.

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.

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.

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.

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 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.

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.

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 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

• S. J. Zaloga (2007) Japanese Tanks 1939-1945, Osprey Publishing
• D. Nešić, (2008), Naoružanje Drugog Svetskog Rata-Japan, Beograd
• L. Ness (2015) Rikugun Guide To Japanese Ground Forces 1937-1945, Helion and Company
• P. Chamberlain and C. Ellis (1967), Light Tank Type 95 Kyu-go, Profile Publication.
• A. M. Tomczyk (2002) Japanese Armor vol.1 Aj-Press
• A. M. Tomczyk (2002) Japanese Armor vol.2 Aj-Press
• The Imperial Japanese Tanks, Gun Tanks Self-Propelled Guns (Pacific War №34) Gakken
• I. Moszczanski (2003) Type 95 Ha-Go, Militaria
• R. C. Potter (1946) Ordnance Technical Intelligence Report No 10,  US Army Technical Intelligence Center