Please take your time and read the blog rules

May 30, 2013

Chi-Ri - Imperial Japan's most advanced tank

SS: Today, we have a guest article from SoukouDragon (US server) on one of the (confirmed) Japanese hightier tanks. Enjoy!

Author: SoukouDragon

A Japanese Tiger? No

When Japan surrendered, American forces discovered Japanese late war military projects all over. One of such was the biggest Japanese tank U.S. forces have ever seen, the seemingly half completed Chi Ri, sitting there without a main cannon installed. The turret was huge. More than large enough for a 75mm cannon. There were some Japanese 88mm AA cannons so Aha! Just like the Germans, they must have been planning on putting these 88mm cannons in the Chi Ri! And behold, the idea of the Japanese Tiger was born.


Recently, in Japan, more research has been going on. In documents about the Chi Ri`s development, there has never been any mention of installing an 88mm cannon in the Chi Ri or on any other Japanese tank. But what these old documents have revealed the reason why the turret was so large. It was meant for a 75mm belt-fed auto loader.

The Chi Ri is big... very big.

Length/Width/Height in meters
Type 5 Chi Ri: 7.3/3.07/3.05
King Tiger: 6.4/3.76/3.09
M4 Sherman: 5.84/2.62/2.74

It could fool anyone into thinking that there was a lot of armor on the thing, like the Tiger. But no, it may be disappointing, but the front armor of the turret and hull was only 75mm. The side armor ranged from 25 to 50mm in thickness. Despite the size, it weighed only 37 tons. This is by no means armored like the 55 ton Tiger. The Chi Ri was not designed as a heavy tank; it was designed as a medium.

So a gigantic medium tank with modest armor…how is that advance? Sounds more like inefficient use of armor…

A Brief Historical Background

1942: Three new anti-tank capable Japanese medium tank projects
Kou: 47mm cannon….eventually grows into Type 4 Chi To
Otsu: 57mm cannon…eventually merges into the hei plan
Hei: 57mm or 75mm cannon…eventually grows into the Type 5 Chi Ri.

During 1943, by looking at the tank battles between Germany and Russia, there was fear that the Chi He and the Chi To could be underpowered by the time they would enter production. At this time, many technological inspections and planning have occurred for the Chi Ri. These included ventilation, transmission, suspension, 550 HP gasoline engine, and easy access to the engine for maintenance. Targeted top speed was 42kph. Improved ventilation was necessary because of the anticipated increased influx of poisonous gas when using the high rate of fire from an auto loading cannon. The main armament would become the Type 5 75mm cannon. It was planned to attach an auto loader to it. Here is a picture of it being tested with the single tray auto loader.

75 mm Gun Type 5

Shell Weight: 6.615 kg
Muzzle Velocity: 821 m/s
Kinetic Energy: 2229 kj
Historical Pen: 75 mm (1,000 meters) goal (met), 80 mm (1,000 meters) expected
Gun Depression in Chi Ri: -6.5 +20

However, steps were taking to ensure an even more advance design could be made available.

In September 1943, a plan 1 and a plan 2 were outlined for the Chi Ri. The goal of plan 1 was to use the current technology developed so far to produce a finished Chi Ri within 1 year. Plan 2 was an ambitious plan to push the edge of technology. The Chi Ri tank discovered by the American forces was the Plan 2 tank.

Chi Ri Plan 1

Chi Ri Plan 2

The biggest difference between plan 1 and plan 2 was the suspension and the turret.

Chi Ri Plan 2 Suspension Options

There was a total of 6 suspension plans examined. Three plans from the Technology Research Institution (TRI) and three from Mitsubishi Heavy industries (MHI).

One plan from TRI was a common Japanese style coil spring suspension which was already proven to work on other Japanese tanks. The other two plans were staggered arranged road wheels much like the notorious suspensions found in German tanks like the Tiger and Panther. One with coil springs like this picture and another with torsion bars.

The three plans from MHI were 6 large road wheels. One was with coil springs and one with torsion bars.
Ultimately, the Japanese went with what they were used too.

The Suspension used very wide treads. The width was 600mm. For a 35 ton class tank, this would have produced a very impressive ground pressure value. The goal was a ground pressure of about 0.6 to 0.7 kg/cm². Compared to other tanks, this was a very good value.

M46 has: 0,986 kg/cm²
KT has: 1.03 kg/cm²
Conqueror has: 0.84kg/cm²
Crusader Cruiser has: 1.04 kg/cm²
Centurion (1 I suppose) has: 1,04 kg/cm²
M48 has: 0.92 kg/cm²
T-54 has: 0.81 kg/cm²
T-34/76: 0.66 kg/cm²
M103 has: .908kg/cm²
M5 Stuart has: 0.856kg/cm²
M4A1 Sherman has: 0.962kg/cm²
M4A3 (76mm + HVSS) has: 0.772kg/cm²
M26 Pershing had: 0.878kg/cm²

Out of all these tanks, only the T-34/76 could match. This makes a very strong case for good hull traverse and low ground resistance. They must have been thinking about rice paddies.

Chi Ri Plan 2 Turret

In order to accommodate a load of 100 75mm rounds and to fit in a belt style auto loader, the turret was enlarged. The plan 1 turret would likely not be capable of handling this task, therefore the large turret was designed. To increase the speed of target acquisition, the turret would rotate by an electric motor, increasing the speed of turret rotation. Another advanced feature was the gyro-stabilizer for the 75mm cannon. It was demanded for the Chi Ri to be able to engage targets up to 2000 meters away so a long range observation device was installed. One other feature is that it was the first Japanese tank, and one of the few tanks in all of WWII, to have a turret basket built in.

Probably the most controversial feature was the secondary 37mm cannon. It was likely intended to be used for soft targets that would be overkill for the 75mm cannon and thus free up the 75mm for more critical targets.

In 1944, the belt fed auto-loading cannon was abandoned. Likely due to the anxiety of trying to create a belt system that would move 900mm long shells around within the turret. However the large turret was already designed. In its place, a single tray auto loader was to be attached to the Type 5 75mm cannon instead thus still maintaining a fast rate of fire. It is believed that very likely the Chi Ri underwent running and shooting trials in March 1945. However, the simpler Type 4 Chi To was selected over the Chi Ri for production. The likely reason why the Chi Ri was found armless is because the Chi To mounted the same 75mm cannon and thus the Chi Ri’s 75mm cannon was likely moved to a Chi To tank.

Adding the Chi Ri to World of Tanks

Here I will describe how the Chi Ri could be implemented into the game as a tier 7 medium tank.

The Engine was a 550 horse power de-tuned version of the Kawasaki H9II 800 horse power engine. At 37 tons, that would give it 14.8hp/ton.

Here is a list of HP/ton of other tier 7 medium tanks with their top engines
T20: 18.6hp/ton 560hp
T-43: 17.6hp/ton 600hp
VK-13: 18.3hp/ton 600hp
VK3002D: 18.4hp/ton 720hp
Panther: 16.6hp/ton 750hp
Comet 20.3hp/ton 650hp

For the needs of the game, a little more horse power would be needed. With the 800 HP H9 engine, there is a lot of potential for upgrades from the 550 HP point. Essentially, a suitable de-tuned value could be determined for balance purposes; as long as it does not exceed 800. A top engine with 675 HP would give the 37 ton Chi Ri an 18.2hp/ton rating.

Gun Choices

Estimated values for 4 cannon modules

Tier 6 Type 5 75mm model II (no auto loader)
AP Damage: 135
AP Penetration: 137
Rate of Fire: 14.5 r/m
Accuracy: .36

Tier 6 Type 5 75mm model I (single tray auto loader)
AP Damage: 135
AP Penetration: 137
Rate of Fire: 19 r/m
Accuracy: .36

Tier 7 Type 5 75mm belt fed auto loader (requires upgrade plan 2 turret)
AP Damage: 135
AP Penetration: 137
Rate of Fire: 30 r/m
Accuracy: .36

Tier 7 Type 5 88mm cannon (requires upgrade plan 2 turret)
AP Damage: 220
AP Penetration: 144
Rate of Fire: 10 r/m
Accuracy: .38

Picture of the 88mm

Hit Points with top turret: 1200

Main Armor type: Cast Steel

Front Hull: 75mm
Side Hull: 50-25mm
Top Hull: 20mm
Rear Hull: 50mm
Bottom Hull: 12mm

Front Turret: 75mm
Side Turret: 50-30mm
Top Turret: --
Rear Turret: 50

Mobility with supposed 675 HP top engine.
Top speed: 45kph
Traverse speed: 38 d/s
Upgraded Turret Traverse: 46 d/s


High DPS with either the alpha hitting 88 or the rapid fire 75.
Good mobility.


Very big tank means very bad camo, difficult to get behind cover.
Weak Armor makes it a punching bag if exposed.

The expected game style of this tank will be taking advantage of its high DPS potential. The 75mm belt cannon gives it insane DPS potential in a sustained brawl but loses out in long range shooting compared to other sniper capable cannons or peek-a-boo tactics with its low alpha and penetration. When wolf packing or against a distracted enemy, the 75mm belt fed cannon will decimate a target in short time. It will bully anything the cannon can penetrate. However heavy armor will nullify a Chi Ri tank armed with the 75mm belt fed cannon.

Something curious about the belt fed cannon is that it seems to be unknown as to how the crew could swap between HE and AP rounds with a linked belt system. In concept, the Chi Ri was designed as an anti-tank medium tank. It could be that all 100 rounds were AP rounds. That does present an explanation for why the 37mm cannon was put on, for it`s HE ammunition. But that is pure speculation on my part. Sadly as I researched into this tank, more questions arise. But anyway, if the belt-fed cannon was to be an AP only weapon, then it does make for a risky play style, but, I feel, a popular niche.

The 88 offers a higher alpha and marginally better penetration for more common brawl style playing. With the higher alpha it gives the Chi Ri the ability to peek-a-boo and premium rounds or the better HE rounds give it the ability to deal with heavier armor better than the 75mm cannons.

While the 88 was not planned for the Chi Ri, the very large turret would undoubtedly be able to handle an 88mm caliber weapon.

What this tank cannot do is run out in the open. It will be spotted. It can’t be sneaky, it is just too large. Its armor can also be penetrated by just about anything. The maximum 75mm armor is not even well sloped.


Maru [丸] 2011 October magazine edition. 平成23年10月一日発行 
WoT Discussion forum: Japanese Tank Tree & Guns Discussion: Posts by Daigensui and Lostwingman.
World of Tanks Wiki 8.5

Next discounted tier 10...

Source: apparently the E-100. From South-Korean server:

Duration : June 1 to June 15

30% discount of following tanks -

Tier VIII : PzKpfw Tiger II
Tier IX : E-75
Tier X : E-100

30% credit income bonus of following tanks -

Tier VIII : PzKpfw Tiger II
Tier IX : E-75
Tier X : E-100


- there will be more Soviet tanks implemented in general (SS: possibly one medium and one more heavy branch at least)
- the first game SerB ever played was "Skeet shooting" from 1974 on BESM-6
- eventually, shells will be able to penetrate a whole tank and damage targets behind it
- Prokhorovka in game doesn't have to resemble the real Prokhorovka: "There are many Prokhorovkas in the world"
- SerB doesn't care about the "In development" portal section
- SerB spends one hour or two per day on forums
- SerB answering, whether he saw the War Thunder tanks: "We've seen it. I'll see, what will exactly be in the game. And when."
- historical battles won't come anytime soon
- SerB on War Thunder: "We - unlike competition - actually heavily prefer cybersport, that's already a done decision. And 'historical battle mode' like the competition has - with MiG 15 over Stalingrad - doesn't make us happy in particular. To do this right is very difficult."
- SerB on War Thunder realism: "The same damage system (as in WT) on tanks - so that a tank will be detracked and won't move for another half an hour? And if you get hit in the gun - that's it, you won't shoot until it is fixed on the base? No, we don't need such a mess. Very few people want it that way in fact - see how few players play the "realistic battles" in War Thunder."
- SerB does drink tea and does smoke
- it's possible British arty will have HESH shells
- various nations don't have to have similiar light tank branches
- US full light tank line will most likely happen, Soviets don't have enough vehicles for a full line yet
- there is no plan to allow light tanks to be taken as "free slots" in Clanwars (SS: as in each team would have a few extra slots exclusively for light tank scouts)
- SerB expects that in 0.8.6 the scouts will remain roughly the same, arty will have more hard time hitting them, so their number might rise
- Q: "Is this your reaction to the fact that Gamebox is countersuing World of Tanks?" (SS: the Chinese company that made the WoT copy)

A: "No comment :)"
- not all the maps that were developed made it to the game, some didn't pass the tests
- according to SerB, the map rotation works okay
- the minor arty name changes (Object 212 to Object 212A) are apparently for historical reasons
- in 0.8.6, arty shell trajectory will remain the same despite arty velocity nerfs
- it's possible, but not yet sure, that arty might be the top tank of the team
- there will be new soundtrack implemented into the game, but not many tracks
- British artillery is practically ready
- Sexton I was delayed because the devs need to implement and balance the tier 10 arties first
- T71 model fix (SS: currently, T71 is not historical, it's a mashup of two various projects) doesn't have a priority atm
- special effects such as rain and snow will eventually come
- press-accounts can choose which map they want to play, they can also disable maps from rotation
- various times of the day during battles will be implemented (SS: dusk, dawn, noon etc...), but they won't be tied to real time
- there most likely won't be more maps for new players (tier 1-2), it would be too complicated for newbies
- arty shell velocity was nerfed, because the devs feel it's too easy to shoot moving and maneuvering targets
- the idea to reduce terrain passability when the tracks are damaged was never considered

The Schürzen - against HEAT?

SS: This is a translation of Tuccy's post on Schürzen. For those who don't know him, Tuccy is a Czech community organizer and a tank buff - in fact, he's one of the most knowledgeable people on any WoT forums, when it comes to real life tanks and history - compared to him, I'm a schoolkid. So when he writes something, it's really worth reading. This time, he wrote about the Schürzen and the widespread myth that they were supposed to protect vehicles against HEAT projectiles. It's basically the same thing that H.Doyle said in Operation Think Tank.


Spaced armor in the form of thin metal plates, so called Schürzen ("skirts") appeared en masse around 1943 and it was immediately misunderstood. Due to the fact it came by the time the Allies discarded their AT rifles and started using hand-held HEAT warhead weapons (PIAT, Bazooka), the western authors have the tendency (supported by copying each other's texts) to state that this was to protect the tanks from HEAT warheads.

Luckily for us, we have our well-informed original sources, that give us proper insight - in form of German documents (for example in Spielberger's books on Panzer III, Panzer IV and Panther). During the Schürzen development, following threats were considered:

- 14,5mm shots from Soviet PTRS and PTRD anti-tank rifles
- HE shells from field guns

Regarding the AT rifles:

June 1941 caught the Red Army off-guard and without proper anti-tank armament. One of the weapons designed to rectify this situations were simple, mass-produced 14,5mm rifles. Compared to their German counterparts, their caliber was bigger (SS: Germans used 7,92mm special long cartridges) and compared to their western allied counterparts, they were often lighter and balistically more powerful - essentially, it was the peak of AT rifle development, beause - unlike early rocked or recoilless guns with HEAT warheads, they were reliable and (what was even more important) they didn't require new industrial capacities.

Their penetration ability (at least 35-40mm at 100m) was fully sufficient to penetrate Panzer III, IV and Panther side armor and proved to be a serious threat also to lightly-armored tank destroyers and self-propelled anti-tank guns. Furthermore, they were used en-masse, a Soviet batallion anti-tank company consisted usually of one platoon with 45mm guns and two or three platoons with 8 AT rifles each.

Regarding the HE shells:

Lack of arms and ammunition in June 1941 led to massive use of HE shells against tanks (in Fall 1941, there were only 10 76,2mm AP shells per barrel on average in the Red Army, they were also BR-350 and BR-350A shells of dubious quality). HE shells fired from field guns (75-76mm) could eventually penetrate up to 30mm of armor and even if they didn't penetrate it, they at least caused spalling.

Since it would be too expensive and complicated to rebuild the tanks, that were destined to be replaced soon anyway (Panzer III, IV), the German engineers accepted the relatively simple Schürzen solution despite the fact that it brought increased weight with it. What was even more annoying that the relatively thin vertical side armor strip of the Panther was also vulnerable to AT rifle fire. First reaction was to initiate the Panther II development - its thicker side armor was designed to counter specifically this threat, but after the success of the Schürzen, the Panther was "saved" by having the skirts mounted on it.

Solving an historical mistery - help required

By Zarax

Since WG introduced the uranium hartkern ammo for the 30mm MK 103 I started researching on the topic.
Trolling from SerB aside, it turns out to be a quite complex subject.

With tungsten imports getting more and more difficult germans started looking into alternatives and in the book "Inside the third reich" Speer himself states the following:

"In the summer of 1943, wolframite imports from Portugal were cut off, which created a critical situation for the production of solid-core ammunition. I thereupon ordered the use of uranium cores for this type of ammunition. 27 My release of our uranium stocks of about twelve hundred metric tons showed that we no longer had any thought of producing atom bombs."

The use of uranium cores in german ammunition was suspected for a long tome, during A-10's GAU 30 development we find the following:

In AFATL-TR-84-03 Historical Development Summary of Automatic Cannon Caliber Ammunition:20-30 Millimeter (ADA140367) Dale M. Davis in pgs 44-47 makes the point that he believes the Germans used Uranium-cored projectiles in the 30x184/30x185B aircraft cannon against Soviet tanks

In 1956 Aberdeen Proving Ground published the Handbook of German Aircraft Ammunition; on page 58-59is their drawing of 3 cm H-Panzergranatepatrone L'spur O. Zerl, a 350 gm projectile at 960 mps,at 300 m it would penetrate 100mm@0,70mm@30. O. Zerl=without fuze. 

Mr Davis gives 7 points why this is an uranium core. I won't give all 7, but some of them are: H-Panzergrenatpatrone (special armor grenade cartridge) with no explosives inside. 

Another note says special projectile with added incendiary effect, with no incendiaries inside. 100mm of penetration is more than any steel core would do. 

It was described "Exclusively for attacking medium and heavy tanks. Practice firing prohibited".

Deep digging on the internet also gave a 37mm round with very similar properties to those described:

This started my search for the experimental usage of uranium cores in other rounds.

This is the report from GAU development:
The holy grail of german WWII historical research "Germany and the second world war" mentioned tests with uranium cores in 1944 but sadly goes no further:

The referral is to a note in "Inside the Third Reich" which itself refers to Speer's Office diary citing his office journal in March 1944.
 Going from this, another deep session of internet search gave out a forum post with the following content:

""A document was from the German Army Ordnance Command (Heeresamt/Heereswaffenamt) about a experimental-commando (Versuchskommando 515) with a staff and two experimental-companies.
1. Company with 2 Tigers, 2 Kingtigers and 5 Panthers are used the uranium-cored ammunition and tested it against Soviet tanks near the town of Posen in Poland.

2. Company with guided anti-tank missiles called "Rotkäppchen" on Halftracks also fighted against Soviet breakthrough´s near Posen.
There was some infantry to accompany. 

In the document the uran-ammunition and the missiles performed very well and the leader of the Experimental-commando says in his statement that the ammunition was many times better than the tungsten-cored round PzGr.40.

Sadly I couldn't find the document but it must be accessible to the public in german archives.
Unfortunately as I'm not german (and sadly don't speak it either) this is the limit of my research.

We do know that uranium ammo testing is definitely real and the forum post above (plus some others claiming an uranium 5cm round was found in Belgium) might very well be based on a real document but proving this will need someone to do the final part of the digging.

With this I'm asking to anyone in germany that could potentially spend some times in the old archives if they are interested to try to dig the document and get a pic or a scan of it.
If successfull, this could unlock knowledge of one of the last "secret weapons" of WWII and potentially a way to ask WG to buff certain german guns.

I cannot offer any reward to this aside from my personal gratitude but whoever will succeed can be proud of having solved one of the last historical mysteries of WWII weaponry. 

More pointers

- Does anyone have "Truth about the Wunderwaffe" by Igor Witkowski?
I found a mention that on page 117 an area near Mieleck is still contaminated by Uranium from WW2 trials with Uranium core amunition.

- Apparently there is a document from 04.03.1945 about the use of uranium-cored
armor piercing rounds  in the German Army history center in Koblenz

- There are also mentions of a pre-WWII Rheinmetall patent on the use of uranium cores.

Hidden tags in WoT screenies


This is how Wargaming identified the supertest leakers (amongst other ways that is). Each screenshot, made by the WoT engine (by pressing Printscreen) will have these tags (they are revealed by fiddling with HUE):

These tags reveal, who made the screenie. This is a gif, linking to how the screen looks when filtered thru proper photoshop techniques:

This is also how one of the 0.8.5 supertest leakers has been identified (see above picture). But there is a way around it. Apart from the obvious taking pictures of your screen with a camera (a method used for early leaks if you remember), you can also use 3rd party program such as FRAPS - in such a case, no watermark tags appear on the screenshots.