Blog Update

Quick update for those wondering why there hasn't been any content these past weeks. I've been on vacation and haven't had time to really dedicate an article for a bit. Right now I have a few being worked on to get out for everyone. Hopefully by tomorrow I'll have the Chi-Nu II finished and put up. Hope everyone had a nice holiday season!

Scheduled:
- Type3 Chi-Nu II
- Type60 SPRG
- Type74

[Dev] Japanese Tanks Review

  DISCLAIMER: This article is to answer player's questions about missing/incorrect data as of the DEV SERVER. Note that much of this is placeholder. Gaijin has put much effort into this tree, and will continue to do so!

Gaijin has shown its players the Japanese Ground Forces Release Tree this past weekend. With it, players got to finally see the heat that Japan will be packing in this upcoming patch: a fully fledged tree, 33 vehicles from tiers 1 to 5, including both regular and premium vehicles. Not a year prior, Gaijin was voicing their doubts about an independent Japanese tech tree, seeing it as impossible. However, this past half year, Gaijin has been hard at work making it for you, the players, who demanded their arrival. Finally the player-base gets a real taste of their work.

On December 10th, Gaijin gave access to the 1.65 dev server from 19.00 GMT to 07.00 GMT the next day to give players hands on playability with the new Japanese tanks and the etc. Players' responses to these tanks were exceedingly positive, even those who had been doubtful of Japanese tank potential prior to testing these vehicles. I, too, am amazed at Gaijin's work and time spent on these vehicles, but it is not all good. Today I'll be giving my thoughts on the Japanese tanks currently as of the first iteration of the Dev server.  To clarify beforehand, I am not going to bash Gaijin. Working with them has and will be a wonderful opportunity for both parties. War Thunder is a game, and like all game not everything will ever be completely accurate. Balance will always come before historical numbers. That is just the play of the game. So with that said, let’s get into it!

Ha-Go - artistic screenshot by user umiraku

The major problem Japanese tanks currently have are their incorrect stats. While the models of the tanks themselves are generally perfect, with a few exceptions, hard and soft stats have proven to be the bane of their current implementation. Most of the common errors in the vehicles’ stats involve things such as gun depression, rate of fire, top speed, and other numbers. The greatest concern is improper penetration numbers; in most cases Japanese tanks are underperforming.

Nearly all of the guns currently in the game lack their proper shell list.Gaijin gave the majority of Japanese tank cannons in game only basic HE or APHE. While the Japanese heavily emphasized armour piercing high explosive munitions throughout the war,  it was not their only option, especially during the later years. Due to this basic implementation, Japanese tank cannons have lower than usual penetration numbers, due to both the missing AP shells and the unhistorical lowered penetration of APHE. This has really limited the usefulness of the tanks in the tree and will force players to use more caution than needed when taking these tanks onto the battlefield.

Here are some tank profiles I find the most notable after seeing the Dev server.


Chi-Ha Naval Short

Model and Paint is very accurate, despite gun flaws. 

The Tier 2 premium for Japan is the Type97 Chi-Ha Naval Short modification. This vehicle was equipped with a Naval 12cm mercantile cannon by the Japanese marine force, the SNLF, as a defense unit on Japanese naval bases and littoral assaults. A series of 14 confirmed units were built in 1944-1945, and stationed in the Sasebo and Yokosuka naval bases. The tanks only saw limited combat by the war's end.

In War Thunder (as of the Dev Server), the Chi-Ha Naval Short is crippled compared to its historical counterpart. The tank currently is only given a single shell selection, HE. Because of this players who purchase this tank was restricted to a standard fuse high explosive shell with the maximum penetration listed at 30mm. The tank is deadly to low tiers with its filler of 2.5 kilograms. Most lightly armoured tanks are often single shotted, while anything above initial tiers will rarely be affected by its blast. Hence the tank's BR of only 2.0. However, the tank historically does not rely solely on HE. In fact the gun had a wide selection of high penetrating shells;

- Commerce Raiding HE (
- Anti-Submarine APHE
- Type88 HEAT
- Type2 HEAT

This tank has potential if it is given its proper selection of shells and a raised BR. However currently the tank is nothing more than a novelty toy.

Heavy Tank No.6

The Tier 3 premium candidate for players is Heavy Tank No.6. In 1943, the Japanese embassy in Berlin had arranged for vehicle testing with German military units. The embassy officers favored the look of the German Tiger and Panther tanks, requesting the Japanese Government to pay for samples. On February 28th, 1944, Japan completed the transaction of the Tiger E. The tank was later given back to Germany as the Japanese Military realized its uselessness to the war effort.

The tank is fairly straightforward to players accustomed to the German tree. For all intents and purposes the heavy Tank No.6 is just a slower Tiger with less mantlet protection. Statistics-wise the tank is good, however the model is questionable since Gaijin has modeled the tank as if it were a later model. Things such as the reinforced turret roof, steel rims, track protection, headlights, and the smoke launchers are all little details inaccurate to the model the Japanese purchased. Nevertheless, the tank seems to fit well at 5.7.


Type5 Chi-Ri II

The Type5 Chi-Ri II was one of Japan's last medium tank development projects of the war. Designed in tandem with the Chi-To, the Chi-Ri emphasized Japan’s choice of the Type5 75mm cannon as the main anti tank gun for the last stages of the war. The Chi-Ri went through numerous variations, The most known being the model with the large turret containing an autoloader. What made this tank stand apart from others was its 3 shell belt-fed autoloading mechanism encased in a large box-like turret. The tank was the second design, hence the name Chi-Ri II. Only one prototype of this design was built.

The Chi-Ri is the staple of the Japanese ground forces. Its unique gun mechanism coupled with large unprotected silhouette and average mobility offers players a unique experience. Many players point out the odd rate of fire and reload of the tank, Currently the tank has a full reload of 25-30 seconds and a belt reload of 4 seconds. Currently this is a balance decision as the tank's historical numbers being as high as 30 rounds per minute. The shell speed historically was too fast and caused mechanical issues and was taken out and rejected. Because of the system not working properly, this gives Gaijin an allowance to play with the numbers to a degree.

Other errors include the turret being mounted too far towards the center of the hull when it was actually further forward; the gun also has a lower barrel cylinder which historically was not mounted. However, the biggest issue is the gun performance (this is a problem for all Type 5 75mm tanks) as the penetration numbers are off. The only shell the gun has at the moment is the Type1 APHE. This has a listed penetration of 139mm at 100 meters. Of course this is fairly overbuffed from the historical number of only 124mm. The Type 5 75mm is currently missing two AP shells, Kou and Otsu. Both shells offer dramatic and needed increases in penetration for the vehicles which use this cannon.

ST-A2

The ST-A2 was one of the first prototypes built for the SDF in hopes to creating a modern main battle tank in the midst of the spread of communism in the East. As its name implies, the ST-A2 was the second of the series to have been completed, in February of 1957. It featured a low suspension. The tank's tracks proved to perform above standards in cross country terrain mobility, and it was selected to further the project that led to the Type 61. 

In War Thunder the ST-A2 is, at the moment, the worst tank model wise. Both the A1 and the A2 have considerable proportion inconsistencies for their turrets and cannons. The A2's turret is much smaller than the historical counterpart, including its gun length (for some reason Gaijin shortened it but kept the A1's?). Because of this, the internal module and crew placement is unusually inaccurate. The crew are all kept tightly packed because of the inaccurate turret size, and this in return causes the ammunition stowage to be crammed around the turret ring, making the thinly protected sides an easy target for any caliber of gun. Currently this tank needs the most work done to it, otherwise it'll end up being the sore thumb of the tech tree.

The ST-A2 mounts a slightly different 90mm tank gun than the one used on American-produced post-war tanks. However Gaijin ingame has simply copy-pasted the American gun for the Japanese. For some time now the penetration mechanics and statistics on these 90mm guns have been glaringly inaccurate, with substantially lowered penetration compared to their historical values. This cripples the guns’ performance quite noticeably.



-Tank Errors as of the Dev Server-

• Ha-Go:  Low Penetration, Lack of Shells.
• I-Go: Low Penetration, Lack of Shells.
• Ho-Ro: High Penetration, Low Depression.
• Type94 Truck: Low Speed. 
• Ke-Ni: Low Penetration, Lack of Shells, Low Speed, Overbuffed Hull Armour.
• Chi-Ha: Low Penetration, Lack of Shells, Low Depression
• Ka-Mi: Low Penetration, Lack of Shells.
• Chi-Ha Kai: Low Penetration, Lack of Shells, Low Depression, Low Elevation.
• Ho-I: Low Penetration, Lack of Shells, Low Depression.
• Ho-Ni I: Low Penetration, Lack of Shells, 
• Ta-Se: Low Penetration, Lack of Shells, 
• Naval Short:  Lack of Shells.
• Chi-He: Low Penetration, Lack of Shells, Low Depression, Low Elevation. 
• Ho-Ni III: Low Penetration, Lack of Shells, Low Depression.
• Chi-Nu: Low Penetration, Lack of Shells, Low Elevation.
• Chi-To: Low Penetration, Lack of Shells, Low ROF, Low Depression, Low Elevation.
• Na-To: Low Penetration, Lack of Shells, Low ROF, Low Depression, Low Elevation.
• So-Ki: Incorrect Gun, Low Penetration.
• Heavy No.6: Small Cosmetic Errors, Overbuffed top turret armour. 
• Chi-Ri II: Low Penetration, Lack of Shells.
• ST-A's:  Low Penetration, High Hull Armour, Wrong Xray, Small Turret/Guns, Low Depression, Low Elevation.
• Type61:  Low Penetration.
• STB-1: Low Depression, Low Elevation. 
• Type74: Low Depression, Low Elevation. 
• Type60: Low Penetration, Lack of Shells. 

Most of these errors seem to be due to placeholders. What was seen on the Dev Server is not entirely indicative of what the actual patch release may bring. Many hardstats such as vertical guidance not being able to depress far enough seem likely to simply be temporary, as their implementation was practically random.

This post would have been more in depth and posted earlier, but some issues have arisen which have occupied my time. However, Gaijin has released the 1.65 trailer recently, so the patch will be coming soon. I had originally planned to make a detailed writeup on each tank individually, but things came up and I'm just went ahead and typed something up quickly to get out. Once the patch is live, I will make a more detailed follow up post for everyone. The Type 74 article will be worked on this weekend when I have time to spare. Stay tuned.

[WT] Japanese Ground Forces Arrived.

Japanese Ground Forces 

Gaijin has shown the playerbase its release tree and dev servers for the upcoming patch! There is a lot to cover and I will have an article post within the next day or so. I have many articles planned for players to help make the transition to Japanese tanks simple. Stay tuned!

[WT] So-Ki SPAA

   Gaijin has shown its players a lot in the last couple of days. As it has been confirmed, Japanese Ground Forces will arrive in the upcoming 1.65 patch. Gaijin has decided to share some of the more interesting vehicles for players to toy with upon their release. Today we will go over the first Japanese anti aircraft tank shown by Gaijin, and what will be one of the first SPAAG’s available to the Japanese, the small but deadly So-Ki.

As far as back as the early 1930's, Japan had been experimenting with anti aircraft mounts on multiple testbeds. From railroad cars to trucks, cars, horses, and especially tanks. In 1938 it was decided to design a new self propelled anti aircraft tank to accommodate the Imperial Army's needs of having a mobile anti air vehicle to aid in protecting troops and armored convoys. The first design that was built was based on a modified Type97 Te-Ke chassis mounting a single Type98 20mm cannon. Under trials, the vehicle was found to be too unstable and could not accurately hit targets. While two prototypes were constructed, the vehicles were scrapped after trials. The Type98 had been the standard light automatic AA cannon used by the Japanese, but due to its low range, the cannon could not hit targets at high-altitude.

However, development of SPAAG’s that could accompany tank units to offer protection from air attacks had not been abandoned. The idea of a mobile anti-aircraft vehicle was given a second wind with the production of the Type2 20mm light anti aircraft cannon. This was a modified Type98 light AA cannon with enhanced muzzle velocity and range. In 1941, Japan decided to retry producing an SPAAG based on an already existing tank platform. The platform which was chosen for the SPAAG was the newly built Type98 Ke-Ni light tank. Two designs were made using this platform, one with open dual mounted 20mm cannons and the other with a single 20mm cannon mounted in a turret. Both designs were labeled as prototype anti aircraft tanks. The dual mounted prototype (second design) received the designation So-Ki, whereas the turreted design received the designation Ta-Se.


The Type98 Ke-Ni hull had been altered substantially during the development process, even more so for the second prototype than the first. The turret and roof plating were removed from the Ke-Ni in order to install a superstructure for the tank. While the new plating added kept the original shape of the tank, the new superstructure was somewhat larger. The driver’s position was near the center in the front of the tank, while the AA mount was placed above and behind. A gun-shield was added to offer the gunner protection from small arms fire. In addition, an armour plate was welded on the forward end of the driver's position. The side and rear armor were arranged vertically. A bench for the crew was mounted on the rear of the platform. This bench could also be folded inwards to create a container that could hold up to 20 magazines for the cannons. The total ammo complement was 22 magazines (assuming the cannons were already loaded).

The So-Ki performed well when it came to the gun performance. The Type2 cannon had performed tests with a recorded muzzle velocity of 900 m/s for its AP-T shells, an improvement over the Type 98's muzzle velocity of 830 m/s. However, upon further research into the Japanese National Archive, I have came across a 92 page report detailing the differences between the Type98 and the Type2 cannons, with some graphs reporting the muzzle velocity for the Type2 cannon to reach 970 m/s with it’s AP-T shell. However this is still being looked into as it takes time to process every page word for word. [12/7/16]. The prototype, while successfully tested, was not accepted into service. This was due to the lack of available resources and the restrictions even the improved SPAAG faced. Japan by this point in the war would have needed significantly better gun performance with a higher fire ceiling than that of the Type2 or the Type98.

A common mistake that many tend to make is with the name of this SPAAG. The tank is known as the So-Ki, yet many have confused it with the Type 95 So-Ki, an armored railroad car. The two vehicles are not related. The So-Ki in this case stands for Sokosha, or armored vehicle / car as its chassis is taken directly from the Ke-Ni. The Type 2 20mm also has the nickname Soki, which is not accidental as this gun was developed first for the So-Ki SPAAG.


Weight: 7t
Crew:
Length: 4.11 m
Height:  2.8 m
Width: 2.12 m
Engine: Mitsubishi Type100
Cylinders: Inline V6 Air-Cooled Diesel
Power Output: 130hp/2100rpm
Max Speed: 50kmh
Armament: x1 Twin Type2 20mm

Gun Shield Armour:
AA Gun Shield: 6mm
Superstrcture - 16mm

Hull Armour:
Front - 16mm
Cheeks - 12mm
Side - 12mm
Roof - 6mm
Rear - 10mm

Suspension:
Front - 30mm
Side - 12mm
Rear - 30mm

[WT] Type61 MBT

   Upon the request of many to see the end tier tank game Gaijin is going to give to you all in the Japanese Ground Forces patch, they recently previewed a tank known to many as Japan's first main battle tank. I would have posted this article sooner, but due to health issues and me simply procrastinating it'd been held off until now. I'll make an article dedicated to the Type61 along at a later time. But here today we will get a closer look at the first mass produced medium tank of post-war Japan, the Type 61.

Up until 1954, Japan had been barred from any military action within its own borders that was not supervised by the United States. All of the tank industry Japan had during the war had been completely shattered by the time of the Empire's collapse in 1945, and left the nation at an all time low for all military production. It was not until the creation of the Japanese Self Defense Force that Japan could start building its own military force independent of American jurisdiction. This decision was agreed upon by the two countries as tensions in the East started to accelerate with the Korean conflict growing more intense. Japan knew it needed a armoured force in case it would need to defend itself from potential Soviet actions. The arsenal at the time of the forming of the SDF only made up a small number of increasingly obsolete American tanks such as the Chaffee and Sherman. Both were deemed too outdated and complex to use extensively in Japan.

Statistics of the fourth prototype as compared
to American tanks.

Japan sought to use the American Patton tank series for influence in designing their own tank. The American built 90mm was heavily desired by Japan for use on any potential tank. However the weight of the M47 and M48 tanks was too heavy to base their own tank off of. Japan's terrain required a lightweight and small vehicle which could be easily transported through Japan’s many rail tunnels. The M47 and M48 were too large for this. Instead, the United States gave Japan permission to design their own 90mm anti tank gun, as they refused to give the license to the nation. The tank project began in 1955 with the envisionment of a light tank, however by the time the first prototypes were completed in the December of 1956, the design had evolved into a medium tank. From then until 1960 the tank project would include a total of 4 prototype designs, each unique in their own fashion. The first two medium tanks were constructed under the names ST-A1 and ST-A2. However, after the tests proved unsuccessful in the end, the ST-A2 prototype was chosen to extend design changes to meet the Ground Staff Office's requirements. 

ST-A4 Prototype.

Initially, the prototype tanks introduced a two stage torque converter manufactured by Sweden 's SRM company, however a problem in power loss and mobility proved to be unsatisfactory for the Ground Staff Office. The next two series of the prototype line were to fix this issue, however it took until 1959 for the ST-A4 prototype to be completed, another year afterwards for the ST-A3. The second stage of the tank prototype series focused on polishing the ST-A2. The changes made in these later models included a design change for the 90mm gun's muzzle break, an increase of the engine’s output, and an increase in quality of the tank shells used with the first generation 90mm. Added to this, with the ST-A3 prototype, Japan tested a new system of a remote controlled 20mm cannon located above the turret accompanied by an autoloading mechanism for the main cannon. This proved to be too expensive for Japan to justify the improvements, and the prototype ended up being canceled in favor of the more practical and simple ST-A4. The ST-A4 was later accepted for completion and after minor changes such as engine enhancements and the removal of the remote-controlled 20mm cannon in favor of a crew-served heavy machine gun, the tank was designated the Type61 Main Battle Tank.

The Type61 production model. 

  The Type 61 proved to be Japan's first post war tank produced on a large scale. However, the tank was already outdated by the time it entered widespread service, with design and mechanical flaws. Due to conflicting requirements issued by the Ground Staff Office, the tank had bounced back and forth between specifications, lengthening the development process. Moving between a series of different weight requirements and levels of gun caliber, armour, speed, and dimensions crippled the tank throughout its development, and this was reflected in the series production model. The tank proved to even be more expensive than what it was worth, and not long after its introduction was it decided to develop a new tank that would surpass the Type 61 and its flawed development history. The crew compartment was arranged so that the driver of the Type 61 was located on the right side, which was done to abide by the traffic laws of the period. This caused the 3 crew (of the 4) to have been unevenly distributed throughout the right side of the vehicle.

One of the largest flaws of the Type 61 was its overall armour protection. The tank had to keep a low armor thickness in order to reduce the weight of the chassis. The tank's hull was inclined at 30 degrees from the horizontal, with welded construction, allowing for the effective thickness to reach 90mm. The turret was casted into a bowl-like shape and was kept to 40mm on the sides, with a slope of only 80 degrees, offering  80mm thickness in theory. The result was that the Type 61’s armor protection was inferior to most other tanks of the period; Japan had only taken into consideration the T-34-85, as that had been the major opponent in the Korean war. The Type 61 in the end was only protected against basic infantry anti tank weaponry, and was incapable of defeating dedicated anti-armor projectiles from most of its probable opponents.

Armour layout of the Type61 Main Battle Tank. 

The mobility of the Type 61 did not make up for the low thickness of the tank's armour. The tank was given a modified version of the Mitsubishi 20WT engine, a 4-stroke 90 ° V 12-cylinder direct injection air-cooled diesel engine, supercharged by two turbochargers, with a displacement of 29.6 liters and a maximum output of 604 hp. This was changed into a 12 cylinder air-cooled turbocharged diesel with an output of 570hp at 2100rpm (650hp without cooling device and air purifier) and a maximum shaft torque of 200 kg/m. Designed to power a lighter vehicle, this modified engine ended up having detrimental effects on the Type 61’s performance. On roads the tank had a top speed of 55kph. Off road, the tank kept a stable 45kmh. The tracks of the tank were 500mm in width, and afforded the Type 61 a 10 meter turn radius. The minimum fuel consumption rate at full load was 210 g / PSh. The main tank is 450 liters, and the auxiliary tank is 200 liters.  The acceleration performance of the Type 61 was 0 to 200 meters in 25 seconds. While this may seem fast for an armored vehicle, the numbers should be measured against those of the third generation tanks of other countries which were deployed later, as the Japanese Defense Agency did. For instance, the Leopard 2A4 is estimated to have a time of 23.5 seconds, and the M1 Abrams' prototype XM1 Is estimated to time at 29 seconds. Both of these vehicles are significantly heavier than the Type 61, however. Considering the power weight ratio of the Type 61, the tank clearly emphasized acceleration performance rather than the maximum speed. Given the mountainous nature of Japan, this was clearly a good development decision.

Mitsubishi 12HM-21WT.

The transmission system of the Type 61 is frontally mounted, the only tank to use this transmission system since the end of WWII. As a result, the height of the vehicle could not be lowered, and part of the front armor plate of the car body became a bolt fastening panel for maintenance of the transmission, and brought accompanying flaws in the armor protection. The transmission was a double differential manual shifter with 5 forward speeds and 1 reverse. This was a departure from the earlier two prototypes of the tank, which were equipped with a two-stage torque converter manufactured by Sweden's SRM Company. however when it was installed, there were problems with power loss and agility, which was not a satisfying appearance to the Council and their requirements. Finally, after trying to emulate the automatic gearshift of the M47 and M48 Patton tanks, more complex systems were abandoned a manual gear-shifting system was chosen instead.Steering was provided by a lever for each track, as in the Sherman tanks. This made the Type 61 considerably more difficult to maneuver than the M24s and M41s originally provided to Japan by the US military.

Interior cutaway view of the Type61. 

The armament of the Type 61 was influenced by the American 90mm. The layout of the Type 61’s 90mm was kept identical, however the barrel was elongated. It used the same standard ammunition as the US 90mm.  Production rights were given to the Japan Steel Works company, with American aid in providing munitions. In accordance to the Defense Agency's file of the gun, XB3002, dated April 26 1961, the gun's barrel was made to 4730mm in length, 52 caliber, weight of 2,500kg, and a barrel weight of 1,150kg. The gun shield had weighed nearly 750kg. According to the Defense Agency's file XD9001, the maximum speed of the turret traverse was 24° per second, The depression speed of the gun being 4°  second.  The gun could also elevate to 13 degrees while having a depression of -10 degrees. The firing rate of the gun ranged from 10 to 15 rounds per minute.

The shells used on the Type61 90mm Tank Gun had been kept similar to the American counterpart, however Japan had produced them under their own conditions. The main shell used in the gun was the Japanese model of the AP-T M318A1. It had a recorded penetration of 189mm at 1000 meters. Calculations of the shell has it listed to 222mm at point blank range, and 158mm at 2000 meters. 

Weight:  19.9kg
Length:  942.6mm
Shell Weight: 11kg
Shell Length: 364mm
Output: 914m per sec.
Range: 21,031m
Pressure: 3,300kg/cm2

Secondary weapons for the Type 61 included a coaxial 7.62mm M1919A4 machine gun, with a range of 800 meters and a rate of fire of 550 rounds per minute. Located on the top of the turret was a 12.7mm M2 heavy machine gun, which had  +55 ~ -10 degree angles, a rof of 550rpm, and range of approx. 1,200 meters.  The 90mm tank shells were stowed into two locations in the tank, directly behind the gun crew in the rear turret box, and to the left and right of the turret in the hull. 

Type61 90mm Tank Gun as drawn by the Defense Agency. 

Weight: 35t
Crew: 4 men
Length 8.19  m
Height: 2.49 m (3.26 m with MG)
Width: 2.95 m
Engine: Mitsubishi 12HM-21WT.
Cylinders: V12 Air cooled Diesel (Supercharged)
Power Output: 570 hp/2,100 rpm (650 hp max)
Max Speed: 55kmh
Armament: x1 Type61 90mm Tank Gun, x1 12.7mm M2 , x1 M1919A4 MG

Gun Shield Armour:
Mantlet: 125mm
Top Front - 40mm @ 60° (90mm)
Cheeks: 90mm
Top Side - 40mm
Bottom Side - 60mm
Roof - 18mm
Rear - 35mm

Hull Armour:
Front - 45mm @ 30° (90mm)
Side - 30mm
Roof - 12mm
Rear - 25mm

Suspension:
Front - 35mm
Side - 35mm
Rear - 20mm

[WT] Type3 Ho-Ni III

To the unexpected majority of players, Gaijin released the first Japanese tank destroyer devblog today. Many expected Japan to not have a tank destroyer branch with the initial release of the ground forces, as was done with Britain and the United States. Japan focused heavily on anti tank vehicles throughout the war, and today we get to look at one of the most known, the Ho-Ni III. 

This is the first time Gaijin showns Japan's late war base paint, Olive. 

In 1939, Japan had grown to understand the need for an anti tank vehicle in the field. The Type97 Chi-Ha with its 57mm cannon was not sufficient in providing support to the infantry against armoured adversaries. Unlike the Battle of Nanchang, where the Japanese tanks were first used successfully as infantry support against the Nationalist Chinese, the Nomonhan Incident against the Soviets had illustrated the need for an anti tank role'd vehicle. After the Japanese defeat at Nomonhan, the Imperial Japanese military initiated a project to design two types of tanks, an anti tank replacement of the Chi-Ha and a self propelled gun chassis with heavy firepower against armour at range. In December of 39, the two projects were called Ho-I and Ho-Ni.

Ho-Ni I prototype during trials. 

The Ho-Ni was designed to be a self propelled gun mounting the Type90 75mm field gun. The development of the Ho-Ni was given to the 1st Army Research Institute, which was the go-to research group involving SPG designing. The Type97 Chi-Ha chassis was selected to be used to produce this tank. However due to resource shortages and the introduction of the Chi-Ha Kai and its anti tank 47mm, the Ho-Ni project was halted for a year. It took until 1941 for the prototype to finish. The prototype used an open thin shielding to replace the turret and was kept practically identical to the original chassis. The prototype finished testing in
 October and was labeled Ho-Ni I.

During the prototype trial tests of the Ho-Ni I, the crew compartment openness and the lack of direct fire scope proved to be an issue to the Army. However due to the need of a tank destroyer, the tank entered production and would not have these problems dealt with until mid 1943. It was only then the Imperial Japanese Army had no choice but to upgrade their tank, as it proved too difficult to target tanks at range. In 1944, a prototype was completed and was approved for service. This tank was named Ho-Ni III (II was a variant of the I adding a new cannon, III was a separate tank).

Rear of the Ho-Ni III.

The gun shields on the original Ho-Ni models were replaced by a single heptagonal superstructure consisting of a thickened frontal plate accompanied by two plate cheeks. Two sides plates, and two rear plates constituted at an angle. The thickness of the new superstructure was limited to only 25mm. This wasn't made to withstand tank shells, but rather simply protection against machine guns and other light anti tank weapons. Because the width of the turret is wider than the upper part of the car body, the left and right sides of the turret were overhanging from the car body. At first glance the superstructure appears to be able to turn around the whole circumference as if it was a turret, but in fact it only had a limited swivel for the main cannon.

Pistol and view ports were placed around the superstructural plating. A hatch with a rectangular and a crab shear type door above the gunner´s position allowed using an indirect fire sight. Unlike the original models, the Ho-Ni III added finally the gun sight into the mount as to provide accurate fire. The gun of the tank was a revamped Type90, the Type3 75mm anti tank gun. It is most commonly known for its use with the Chi-Nu medium tank. However, the gun had a weight of 1,000kg with a 75 x 424R shell cartridge. The standard armor piercing projectile was an APHE shell (Type1 APHE) found with many Japanese tanks throughout the war. It had a shell weight of 6,600 grams and was capable of penetrating 84mm of RHA at a distance of 500 yards. According to the U.S Military in August 1945, the armor piercing capability of the Type90 anti-tank artillery cannon (again, identical to the Model I and II of the Type3 75mm) is provided through a set of APHE shells, which can penetrate:

Ho-Ni III outline. The tank had -15 gun depression.

(at a 90 degree angle of impact)
2.4 inches (61 mm) at 1,400 yards(about 1371.6 m)
2.8 inches (71 mm) at 1,000 yards (about 914.4 m)
3.0 inches (76mm) at 750 yards (about 685.8m)
3.3 inches (83 mm) at 500 yards (about 457.2 m)
3.5 inches (89 mm) at 250 yards (about 228.6 m)


The muzzle velocity was 668 meters per second.   The testing results of the Type1 APHE shell were mediocre and did not meet the requirements of the cannon. To improve on this, the Army developed a Tungsten-Chromium steel anti-tank shell known as the Type1 AP Tokko Ko. This shell had an improved muzzle velocity of 683 m/s and was capable of penetrating 100mm of RHA at 500 yards, and 85mm at 1000 yards.  The Kou was made of nickel chrome molybdenum steel mixed with molybdenum for nickel resource conservation due to Japan's lack of available resources at the time.


The Ho-Ni III, by the time it entered production in 44, was restricted to use only in the Japanese home island. Total number of Ho-Ni III's was numbered to 41, and they were issued to the 4th Tank Division during the homeland defense program. All were destroyed and scrapped after Japan's surrender in 1945.

Weight: 17t
Crew: 5 men
Length 5.52  m
Height: 2.37  m
Width: 2.33 m
Engine: Mitsubishi SA 12.2 0 VD
Cylinders: V12 Air cooled Diesel
Power Output: 150 hp/1,500 rpm
Max Speed: 40kmh
Armament: x1 Type3 75mm Model II

Gun Shield Armour:
Mantlet: 60mm
Front - 25mm @ 78°
Cheeks: 25mm @ 78°
Side - 25mm @ 75°
Roof - 10mm @ 10°
Rear - 20mm @ 25°

Hull Armour:
Front - 25mm @ 82°
Side - 12mm @ 75°
Roof - 16mm
Rear - 25mm @ 90°

Suspension:
Front - 25mm
Side - 25mm
Rear - 20mm

[WT] Type2 Ho-I

   Today Gaijin released their first devblog of the week. Although we did see this coming with the accidental preview with the Chi-He developer diary last week. Probably would have had this out hours ago but I had writer's block yesterday, so never got to post anything this past week. Although this week I have a feeling I'll be posting plenty to make it up to you all. But without further ado, today Gaijin shows you the first assault tank of Japan's tech tree, the Type2 Ho-I.

As Japanese tank development expanded over the course of the 30's, the Imperial Japanese Army toyed around with the idea of a tank with the sole purpose of providing artillery support from a self propelled vehicle. As the Second Sino-Japanese war developed, Japan knew they needed a vehicle to rely on for mobile fire support. The concept of a field gun mounted on a tank chassis to breach hostile fortifications with the use of high explosive shells had become popular around this time. Germany would later produce their own tanks of the class such as the early Panzer IV units with their short, low velocity guns.

Type41 Rentai Ho.

Japan had started out well in the conflict with the Nationalist Chinese. Eventually, however, the Japanese began suffering heavy casualties street fighting in major cities such as Shanghai. The battle proven Type89 medium tanks were the standard infantry support at the time, but were crippled by their lack of power with the Type90 57mm tank cannon. Chinese fort towers and pillboxes proved too much for the gun's capabilities.  To combat these targets, the Japanese troops relied on towed mountain guns. However, with mobility now becoming a necessity, Japan decided to develop a new gun to fit on a tank chassis. In 1937, Japan’s4th Technical Research group decided to work on the self propelled gun concept into a gun tank, dubbed Hosensha ("Gun Tank"), or Ho-I.  The Type41 "Rentai Ho" Mountain Gun was chosen by the research group to be modified and extended for use in the tank project. This cannon was a licensed version of the German Krupp M.08.

Type99 75mm Tank Gun Model I.

 By December of 1940, the Type41 Rentai Ho had been redesigned as the Type99 Tank Gun Model I. Keeping the same 75mm caliber, the first model of the gun had a weight of 543kg, loading a 75 x 185R cartridge.  This is the same as the Type41's design, but it was a completely redeveloped artillery cannon which adopted the same horizontal plug as used on the Type94 mountain gun. Therefore, ammunition for Type41 was also accessible to the Type99. However, because of the low muzzle velocity of the Type41, a new standard ammunition tube was developed, which increased the velocity by altering the charge while using the same cartridge as the Type41. As a result, the initial speed increased from 360 m/s to 445 m/s. However, due to resource shortages the Type41's munitions ceased production, hence only the 3 shells developed for the Type99 were issued. These included the Type94 HE and Type 1 APHE.

During the spring of 1941, Hitachi Ltd constructed a prototype of the Ho-I using the Chi-Ha chassis as the basis of the tank. The prototype participated in a series of tests in September, however the Army deemed the tank insufficient as the gun handling was poor against a moving target and the low penetration capabilities were noted as too poor to rely on. The project took a delay as the Type99 tank cannon had to be redeveloped to fit the Army's standards.

Ho-I Prototype during combat trials at the tank school. 

The Ho-I's turret design was based of the Chi-Ha Kai turret, but used a welded construction which was rare among Japanese tank designs at the time. The result was a large box like structure that gave considerable room. As Japanese tank development continued, however, the Chi-Ha chassis slowly became more obsolete as a battle tank. To replace the tank, the Japanese designed the Chi-He medium tank as the new standard for the Army. The Ho-I was decided to instead rely on the Chi-He tank's hull to improve armour conditions.

Type2 Ho-I

The second Ho-I prototype had been completed in December of 1942. The turret was redesigned by Hitachi, Ltd, The upper slope of the turret was removed and the sides had instead been heightened. The side armor plate were now strengthened by supporting rivets. The frontal armour thickness of the turret was increased from 25mm to 50 mm. The front mantlet had also been changed, this time having better angles to deflect enemy projectiles. This time the tank chassis was manufactured by Mitsubishi Heavy Industries, and the gun was modified to be closer to the Army's standards.

The velocity of the Model II gun was increased to 443m/s for the APHE shell, achieving a general number around 70mm of penetration at 100 meters, and kept the Type94 HE shell from the initial tank gun. With the Model II, a HEAT shell was developed for the tank, labeled Type2. The shell was a molded explosive charge that had the capability of 100mm of penetration at all ranges. The Ho-I by 1942 has changed its initial doctrine from infantry fire support and was, rather, a reliable method of engaging the American M4 Sherman with high firepower. In 1943, multiple tests were conducted against a captured M4 tank, and had achieved successful penetration of the tank's front from 800 meters with its HEAT round.

Ho-I with 57mm.
Both 75 and 57 models had -15 degrees.

Despite the success of the cannon, the Army had already began development of an experimental high velocity 57mm anti tank gun Kou for universal use. The Ho-I with the 57mm would later become the first prototype leading to the design of the Type4 Chi-To. However, by the time the Ho-I had entered service in 1943 as the Type2 Ho-I, the tank was kept in reserve with the 4th Tank Division due to the suspected invasion by the Americans. By the war's end in 1945, only 30 units were manufactured, none saw combat, and all were destroyed after.

Weight: 16.7t
Crew: 5 men
Length 5.73 m
Height: 2.58 m
Width: 2.33 m
Engine: Mitsubishi Type100
Cylinders: V12 Air cooled Diesel
Power Output: 240 hp/2,000 rpm
Max Speed: 44kmh
Armament: x1 Type99 57mm , x1 Type97 7.7mm MGs

Turret Armour:
Mantlet: 60mm
Front - 50mm @ 80°
Side - 35mm @ 75°
Roof - 16mm
Rear - 20mm @ 78°

Hull Armour:
Front - 50mm @ 72°
Side - 25mm @ 75°
Roof - 10mm
Rear - 20mm @ 90°

Suspension:
Front - 50mm @ -42°
Side - 25mm @ 90°
Rear - 20mm @ 85°

[WT] Type1 Chi-He

    Today Gaijin gave you all yet another devblog, this time something a bit larger and more powerful than the I-Go. Today's tank marked a new era for Japanese tanks; no longer were armoured units solely for infantry support-- now they were for tank hunting. Today's beast may not have seen the combat she was constructed for, but the capabilities this tank provided would have marked a challenge to its opponents. Today we will take a closer look into the Type1 Chi-He. 

After the results of the Nomonhan Incident (Battle of Khalkhin Gol) of 1939, Japan understood what it meant to face off against a major power. Here they learned a grueling lesson of the challenge posed by combined-arms warfare. The Japanese lost the battle, but their tank corps ended up being successful when put up against the sheer number of Soviet tanks outnumbering them. The Japanese 37mm and 57mm caliber guns proved adequate against the Soviet tank units, which were dealt heavy losses. However, Japan knew they would need to design better units in order to keep up with the rapid development of modern tanks which other nations started introducing. Japan began development of a gun purposed solely for anti tank capabilities, and ended up with a 47mm cannon. The development of the cannon began in the August of 1939, but Japan also knew a new tank chassis would have to be designed to accommodate the 47mm.

Chi-Ha Kai with the Shinhoto turret and 47mm gun. 

In early 1940, the Japanese Technical Bureau began development of a new tank, which was to be named "Chi-He," based off of the Chi-ha. The tank was to focus heavily on increasing the base armour of the original vehicle, as the Chi-Ha was increasingly seen as inadequate in defensive properties. At the time of development, the Japanese military had been testing an experimental tank, the Type99 Chi-Ho, which mounted one of the original turrets designed for the Chi-Ha tank and the test model of the 47mm. The tank never was approved for service, but the turret was selected for further development, and would later become known as the Shinhoto turret. The Japanese needed to produce large quantities of tanks without the reliance of heavy industrial capacity, in order to achieve this the shinhoto turret was selected for use on the already battle proven Chi-Ha chassis. This tank was designated the Chi-Ha Kai, and when the 47mm was completed in 1941. The newly completed Type 1 47mm, the gun was mounted on the Kai model for deployment throughout Japanese territories.

The Chi-He project decided to use the Chi-Ha Kai's shinhoto turret and advance on it. The shinhoto turret was still spasely armoured like the chassis of the Chi-Ha, and lessons learned from the Chi-Ho indicated that welded face-hardened steel was the best way of improving the armor of the tank. This differed to the standard tank construction method of using riveted connection of steel plating. Production of the prototypes began in late 1941, but was delayed due to the successful results the Chi-Ha Kai achieved in the field. It took until September of 1942 for the first prototype to be completed and tested.

The Chi-He Medium tank. 

Development of the Chi-He was assigned to Mitsubishi Heavy Industries, the primary manufacturer of the Chi-Ha medium tank. The tank was characterized by its single flat armour plate at the front, whereas the Chi-Ha had a protruding drivers port with a slight curvature. With the removal of the diver’s armored vision port, the hull of the Chi-He was lengthened by a few centimeters. This enabled the addition of a crew hatch which would have been impossible with the design of the Chi-Ha. The armour plates had a thickness of 50mm at both the upper and lower frontal plates. The Chi-he was given two headlamps on both the right and left fenders as opposed to the Chi-Ha's single center mounted light. On the sides of the Chi-He's hull were two vision slits for the crew inside, in order to improve on the poor visibility offered to the driver by the Chi-ha-Kai. As per requirement of the Army, the Chi-He was to use only singular and straight planes in the design structure. This would increase the overall length of the Chi-He to 5.7 meters, whereas the Chi-Ha Kai remained at 5.5.

Type1 Chi-He captured by the U.S. intel in 1945.

 The turret was kept practically identical to the Kai's, however the turret received bolted armour shielding around the front, giving the turret 50mm of armour in total. The mantlet ring was held together by a riveted 60mm frame. The sides and rear of the turret, however, remained at just 25mm thickness. The crew of the turret increased from 2 to 3, giving the Chi-He a total crew count of 5, opposed to the Chi-Ha's 4. The additional turret crew-member was stationed behind the gunner to the left side of the turret, and was given the task of loading the gun. The additional space provided by the Chi-he’s hull also allowed for stowage of 121 shells as opposed to the Chi-ha’s 101.

Rear view of the Type1 Chi-He.

The tank was also given a new engine that brought a unique feature into the fold. The newly developed Type 100 air-cooled diesel V12 engine achieved 240 horsepower with 2000rpms. The Chi-He achieved speeds of 48 kph on roads and 39 kph offroad.  The engine was an improved model of the Chi-Ha's 170hp SA12200VD. In order to fit, the engine compartment had to lengthened and the sloped upper armour had to be replaced with a flat plate. The rear plating consisted of a vertical upper plate and a sloped lower plate, which were welded together. The total thickness of the rear hull was left with only 25mm.

Chi-He's 15 degrees of gun depression. 

Such changes meant that production of the Chi-He kept being delayed until the development of the tank was completed in 1943. It was only then the Army staff took the tank and tested it against the Chi-Ha Kai. Naturally, the tank outperformed the Kai in all categories. During the tests, the Japanese used a Type96 15cm cannon against the Chi-He. The tank was shot from an angle diagonal to the chassis's right side, and survived the shot. However, the tank's riveted plates were torn apart and the damages were deemed unsalvageable. The welded plates kept intact from the blast. The tank was given the designation Type 1 Chi-He, and was ordered to be produced immediately. However, it was 3 years late and by this time the tank was already outdated compared to the quickly multiplying M4 shermans. The first 5 units rolled out in February of 1944. By the end of the war in 1945, a total of 170 units were manufactured. Despite this number being fairly large for a Japanese production run of the period, the tank never saw combat. This was because the tank was kept at the home island of Japan under the homeland defense act. Here the Japanese kept most late war tanks for preparation of a possible US invasion of the home islands of Japan.

Weight: 15.2 - 17.2t

Crew: 5 men

Length 5.7 m

Height: 2.4 m

Width: 2.3 m

Engine: Mitsubishi Type100

Cylinders: V12 Air cooled Diesel

Power Output: 240 hp/2,000 rpm

Max Speed: 48kmh

Armament: x1 Type1 47mm , x2 Type97 7.7mm MGs

Turret Armour:

Mantlet: 60mm

Front - 25+25 (50mm) @ 78°

Side - 25mm @ 75°

Roof - 10mm

Rear - 25mm @ 90°

Hull Armour:

Front - 50mm @ 72°

Side - 25mm @ 75°

Roof - 10mm 

Rear - 20mm @ 90°

Suspension:

Side - 25mm @ 90° 

Rear - 20mm @ 85°

[WT] Type89 I-Go

 
    Today, Gaijin released their newest devblog, and oh boy is this tank difficult to explain! So, this can probably be blamed on me and my lack of quick response to Gaijin long ago when they asked me to be a consultant for Japanese Tanks and their development. Due to being a busy person I did not have the free time, so they started to work on getting Japanese Ground forces to their players without me, that's only natural. The problem they didn't understand with the I-Go is that the tank has many different models, the naming of which could also be confusing. So without further ado, let's talk about the Type89 I-Go. 

This is the I-Go Ko 1933.

Background

Japan had seen the capabilities of tanks in the military after the First World War erupted. The Great War had illustrated the strategic and tactical transition forced by mechanization and new weapons. These changes frightened the Japanese, who had no major initiatives for armament or organization, and whose doctrine remained unchanged from the Russo-Japanese War, over a decade earlier. Japan decided to purchase a series of tanks from Britain and France in order to initiate their own tank design. With this came a series of Renaults, a Mark.IV Female, and a couple Medium C tanks. In 1927, Japan had constructed their own tank, the Experimental I. This tank was successful and proved Japan could manufacture their own tanks, but the prototype was too complex with too many parts to replicate. Instead Japan decided to use the British medium designs to make a mass production tank.  

Japanese Vickers Medium C, 1927.

In the March of 1927, Japan had also received 3 Vickers Medium C tanks from Britain for additional influence in designing a mass produced tank. Initially, the tanks were favored upon the Japanese until during one trial when the vehicle maneuvered up a hill the excess gasoline exhaust transitioned into the crew compartment and caused an ignition inside the tank, severely wounded two of the crew. In order to prevent future mishaps like this, Japan decided use safer designs such as the diesel engine for their tanks. This took time, all the way up until 1933 for the diesel engine to be designed for their first produced tank on large scale.

After the successful test of the Experimental I tank, the Army developed a sort of boasting confidence that they, too, could produce tanks which could compete with those of other nations. They decided to design two tanks, a light tank of 10 tons, and a heavy of 20. Japan had decided to use tanks to support the infantry in the field, as was commonplace during the period. The light tank was to be produced in large quantities and be able to keep up with the trucks at the time, these would make up the significant force of the tank unit. The heavy tank would be produced in very small numbers and be used as provisional aid in an assault. The 4th Technical Research Group in the March of 1928 began designing a light tank and had finished the initial schematic drawing  in August of the same year. In 1929 the 4th Research group send the plans to the Osaka Arsenal, the facility that built the Experimental I prior, and construction finished in April. The tank was labeled Trial Model No.89 Light Tank.

I-Go prototype during trials, 1929.

The Prototype

In October of 1929, the prototype went through a trial exercise where it drove from Tokyo to Aomori to see how much the tank could handle under long distance pressure. The tank traveled under its own power for a distance of 660km, and was officially recommended for series production by the staff afterwards. The prototype took influence from the Medium C and its flaws, the tank used a remodeled and simplified version of the C's suspension design, with 4 pairs of roadwheels connected by a set of bogies and semi-elliptical spring placements, a ninth roadwheel placed in front of the forward road wheel in order to achieve superior climbing and trenching capabilities. This was a major improvement over the Vickers C, which was not capable of handling steep inclines and damaged the vehicle as a result. The tank had five return rollers, rear driving sprocket, and a forward idler wheel. The tank used a 6mm cover protecting the suspension system. This was mainly designed to prevent Chinese and Soviet infantry from damaging the complicated and high maintenance suspension in combat. The frontal armour of the prototype was divided, with the upper 1/4 mounted with vertical plating and the lower 3/4 sloped. On the bottom plate in the front, a crew hatch was implemented to the right of the tank where the machine gunner was seated.

Prototype as seen in the side profile. 

The prototype used a licensed built 6 cylinder Daimler water cooled gasoline aircraft engine with an output 100hp, which was located to the right in the rear of the chassis. It was accessed with a small hatch from the crew compartment. It was supported by an 180ah battery to give enough power to start the ignition. Gasoline tanks were placed on the sides on the plate above the suspension, the oil tank being placed left of the engine.

In the crew compartment the driver was located left of the tank (looking forward, not at) behind visor port. The MG gunner sat to the right operating a Type3 light machine gun mounted behind the front armour plate. Several ammunition boxes were placed on the right of the bow gunner, adding up to 2800 machine gun cartridges. To the right and left of the tank contained small boxes of rounds for the primary gun, 110 shells.  Similar to the design of the Experimental I, the turret was a slight conical shape but had a protruding extension to the drivers side that contained a second Type3 light machine gun, 180 degrees apart. To the left of the MG was the rear turret hatch for tank commander to use when needed. The commander of the tank acted as the primary gunner and loader, while the second turret crew was stationed at the MG at the rear of the turret. The primary gun was a Vickers 57mm due to the Type90 57mm still being developed for the tank series.

Pre-Production

The prototype was accepted and in late 1929 the tank entered service with the military. It was designated the Type89 I-Go medium tank. The tank gun was finished in 1930, however production numbers of the gun were minimal and could not be iterated on the first production tanks completed. As a result, the first I-Go tanks mounted a 37mm Sogekiho Infantry cannon. This model of the tank was very rare.

First I-Go tanks had a 37mm gun, divided front plate,
vertical cupola, and two headlamps. Did not have
tail. 

These 37mm I-Go tanks were only produced with 5 units, and only saw combat on February 1932, Shanghai. After the results of the Manchurian Incident, Japan and China had broken out fighting in Shanghai. The I-Go tanks were placed in the 2nd Independent Tank Company, accompanied by 10 Renault tanks. It was here the Japanese knew that their tanks needed tails for trenching and gap crossing due to the nature of the city's layout. This proved to be the first combat scenario the Japanese were met with that had both sides shooting one another, so the crews of these tanks were interviewed after the battle had ended.

The tanks performance was satisfactory, but many changes were recommended. The tank did not have a mantlet, this created a noticeable gap when the tank gun when elevated, allowing Chinese infantry to shoot the tank crew. In order to fix this issue the tank was given a small box shield in the next version of the tank. The armour of the initial tanks was divided by a sloped underside and a vertical front. This was met with challenge as Chinese infantry guns that targeted the sloped underside bounced and often hit the center hull, causing disruptions. This too was changed in the Kou model with an all vertical plate. These changes would be made starting in 1933.

First Production

 First iteration I-Go Kou. 

The first production models were issued with the completion of the Type90 57mm, and production of this series of the vehicle began in 1931. This variant was labeled as the Type89 I-Go Kou. The tank was produced right after the 5 37mm models and formally entered service later that year. The first production model of the I-Go mounted a water cooled gasoline engine, though the front plate was still composed of the same two-part angular lower glacis and flat upper glacis. The I-Go Kou otherwise kept the design of the pre-production model and used a vertical cylindrical observation tower with 4 slits for viewing. Instead of a single turret hatch on the top, the tank was given two hatches, one on the left, and one on the right. The right hatch was under the cupola tower. The tank kept the traditional suspension system of the prototype, however it was changed by removing the track hooks on the pre production model. This was the last model to feature two-part crew hatches in the front of the vehicle. Additionally, the 1932 model of the I-Go Kou would be given shorter track links made of better steel to reduce overall track wear and provide better maneuverability in rough terrain.  

Second Production Model 

In 1933, additional improvements were typed into an official second model; rather than retain the flat upper glacis, the I-Go’s frontal armor was reshaped into a single sloped piece, mounted on the front mud guards. This single piece was riveted, and featured additional armor on the front hatches.

Early 1933 iteration. 

To add to the confusion of identifying the various models of the Type89, many of the second production models retained the turret of the first production model and its cylindrical cupola. This was largely a matter of convenience: Japan’s production capacity was limited, so there was an impetus to use whatever was available. Eventually, all models produced in 1933-1934 were produced with the new mushroom-shaped cupola that replaced the older conical observational port. While these improvements were officially introduced in 1932, they are mostly identified with the later 1933 and 1934 models. Otherwise, the second production model still maintained the water cooled
gasoline engine. It was the least-produced out of all
the Type 89 variants.

Late 1933 iteration. (This is the model Gaijin has for War Thunder. )

Third Production Model

Starting in 1934, the tank used a new suspension type in order to improve mobility. The drive sprocket was moved forward by 50cm (10in) in order to increase the traction control; the suspension mounting position was lowered by 15 cm, thus raising the hull further off of the ground. The number of upper return rollers was decreased from 5 to 4. The upper track roller support frame was removed, and the upper track wheel was changed to a cantilever style suspension mechanism. This model kept the same engine, but had a new crew placement of the driver on the left, and the MG gunner on the right. The turret was given a rangefinder, and the armor was improved slightly. An additional battery storage compartment was mounted on the upper hull, since the ignition motor had been improved and now required more power. Accordingly, an inspection door was installed on the upper surface of the rear portion of the vehicle body. The exhaust port of the muffler was changed to a cylindrical shape.

Third production model (1934) of the I-Go Kou. 

The late models of this tank

also mirrored the crew positions.

Prior to the late 1934 production models, the driver was located  in the right side of the tank (looking from crew perspective), and the Mg gunner was on the left with its own access hatch. With this third iteration of the tank, the crew swapped places. The hatch was located on the right along with the MG position. The driver was moved to the left.

Final Production Model - Otsu 

The last model of the I-Go was not called Kou. Japanese engineers had originally intended to mount a diesel engine in the original prototype for safety purposes and easier field maintenance. However, Japan had neither the experience or tools necessary to produce such engines when the original model was fielded. Only in 1935 were the first diesel engines completed and ready for use in the Type89 I-Go. The tank remained almost identical to the late 1934 model Kou, With this new engine, the radiator that had taken up the left side of the engine compartment became unnecessary. As such, the fuel tanks which were once mounted on the left and right sides of the hull were moved into the space vacated by the radiator. Production of this model began in 1934, but it did not enter serial production until 1935.

I-Go Otsu

To free up additional space, the battery and oil containers that were in the engine room on both sides of the tank were transitioned to the sides of the vehicle. Fuel replenishment pallets were installed on the right upper surface of the tank. One lubricating oil supply pallet was installed on the upper rear of the tank. The armor grill over the radiator was changed to a hinged design which opened to the left. This gave access to a siccoro fan which pulled air through a pipe and into the diesel engine itself. The battery inspection door in the center of the rear slope of the tank chassis was also enlarged. Since the vehicle no longer used an aircraft engine the water-tank lid and the lubricant supply lid for the radiator, which were located on the upper surface of the rear part of the tank, were removed. Also removed were the carburetor and its service hatch, while the muffler was changed to a triangular design.

Believe it or not, but this is only going over the official production models. The I-Go underwent many, many field modifications. Keep in mind two tanks may be the same model yet have small differences. This is because two corporations took part in producing the I-Go, Mitsubishi Heavy Industries and Tokyo Manufacturing Plant. Both were new factories, both had their own unique appearance of the I-Go Kou tanks. Besides this, there were other variants down the line. This is why the tank is very, very complex.