Buff My Tank: Chi-To

Author: Daigensui

A problem with Japanese armor research is that most of the records have either been destroyed by firebombing, burned up after the surrender to hide involvement, carried off to the United States where they became lost (along with perhaps problematic translations made), or kept sleeping in private collections. That is why there is relatively little material to work on, leading to endless copying of the same old research (and the accompanying spreading of myths, like a 88 mm gun for Chi-Ri). However, not all is lost, since even now there are new discoveries happening.

I’ve been looking through the archives recently at the National Institute for Defense Studies (when going to Tokyo on business), and came across two files which might be used to buff Chi-To, and by extension Chi-Ri, in the future. While I cannot guarantee anything, given that these are historical records, WG might include them for accuracy in later updates. We’ll see.

For your convenience, I’ve reverse-searched the digital versions of the files at the Japan Center for Asian Historical Record, so look there if you want to do research for yourself.

7.5 cm Tank Gun Type 5 Penetration

The current penetration for 7.5 cm Tank Gun Type 5 is based on two test records from late 1944:

1) Imperial Guards 3rd Division: 100 mm penetration at 1,000 meters
2) Research Team of Army College: 118 mm at 300 meters, 115 mm at 400 meters, 112 mm at 500 meters.

Using these as the basis, WG came to 124 mm for penetration at 100 meters. While it would be nice if I was able to see the documents myself, they are currently held by the JGSDF, making research very difficult. Thus, we relied on the writing of Japanese authors for these two.

Anyway, I came upon this document, which had the following chart:


Test plate: steel plate (not RHA) at 90 degrees.
Test Gun: 7.5 cm Tank Gun Type 5
Test Ammo: 7.5 cm Armor-Piercing Type 1

100 m: 200 mm
400 m: 180 mm
650 m: 160 mm
1,000 m: 140 mm
1,600 m: 100 mm
2,500 m: 60 mm

According to Japanese records, apparently steel plates had 20~25% less protection than RHA, although I frankly think it goes up even more for decent RHA. Supposing we use 30% less protection, it gives us something like the following:

100 m: 140 mm
400 m: 126 mm
650 m: 112 mm
1,000 m: 98 mm
1,600 m: 70 mm
2,500 m: 42 mm

Now, why did this happen? Frankly, I’m not sure, since the report is pretty straightforward, going immediately to “practical” applications of at what distance a Sherman, Churchill, and “M1″ Heavy (T1 for us) would be penetrate. In addition, the use of “steel plate” is troublesome, since it throws off our preception of what we’re dealing with. While it is true that steel plate was considered 20~25% weaker than RHA, this is quite off when the Soviets general used 50% off as their standard. All in all, what we can say is that the round had become more penetrating, as can bee seen at the 1,000 meter penetration (98 mm), which is similar to the Imperial Guards 3rd Division test.

If I am pressed to propose a theory, I would say that the downfall of the IJN was the leading factor in this. Despite IJA having received more funds, it was IJN that was technologically superior, with better propellent, better explosives, better access to good material (although not on an absolute scale amount). With IJN basically disappearing as a force from the face of the earth with continuous disasters, IJA could have a virtual monopoly. In addition to this, the loosening of IJA headquarters’ hold on research was lessened. Originally, IJA heaquarters had the tendency to interfere with the research of the engineers, which was why Japanese tank development was so retarded. Be it forcing the production of “hard” steel (leading to brittle plates that was easily destroyed by higher velocity rounds and problems with welding), delaying tank gun development on the grounds of unnecessity and rate of fire (apparently HQ demanded that guns be shoulder-supported, to ensure faster aiming and rate of fire, never mind limitations to caliber), or not keeping up with the times (asking for small upgrades when the engineers were already sure of greater ones). By 1945, much of the HQ interference was either lowered or ignored, with the example of Mitsubishi going its own way with armor plates to finally make RHA of world standard.

Of course, this is just speculation on my part, and frankly I’m not sure myself. What is known, is that by 1945 ammo quality had gone up, with even the US military noticing it. Thus, so far in WoT, we’re using 1944 results when by mid-1945 things have gone further.

Reference online: 『対戦車戦闘の参考(戦車関係)補遺』、アジア歴史資料センター。 C14060869100。

Chi-To Combat Weight

Sometimes you find unsuspected things while looking for something else. In this case, I came across the following while researching landing-crafts for my own personal reason of material for fiction writing:


This is the testing layout of the Experimental Large-Sized landing craft, basically a bigger and upgraded version of the Toku Daihatsu-class landing craft. It was 25 meters long, 4 meters wide, and 2 meters deep, with a fully loaded displacement pf 62.27 tons. It would have been able to go at a crusing speed of 8.9 knots for 2 days.

For our purposes, what is important in that drawing is the loaded tank. You can see that it is labeled “Chi-To”, along with the note “Fully Equipped Weight 29.5 Tons”. What is the importance of this? This is the first primary source I have seen of Chi-To’s combat weight. So far all we had were secondary information from researchers who were either involved in development (Hara) or related to them (Mitsubishi), and those measurements were of the prototype Chi-To at 30 tons. This primary source, which was written in 1945 when the production Chi-To was to come out, means that we have data that matches things closer to what the production Chi-To would have been like. Ultimately, this means we need to reduce the weight of Chi-To in the game.

As a side note, I have a theory on why this Experimental Large-Sized landing craft was supposed to be able to carry Chi-To. It was likely to be used to ferry Chi-To across straits to reinforce defending troops. Basically, since logistics was messed up anyway, IJA probably figured they might as well take chances individually instead of risking losing everything by sending in one boat. IJA had lost thousands of men and tons of supplies when a few transports were suck while being sent to reinforce New Guinea.

Reference online: 『設計/大型発動艇 一般配置図』、アジア歴史資料センター。 C12122163300

In conclusion, I have shown that the penetration of 7.5 cm Tank Gun Type 5 could be buffed, and combat weight of Chi-To could be reduced. While I doubt the former would be implemented for Chi-To (we already have a well-balanced gun), it can certainly be used to help buff Chi-Ri, with an estimated 175 mm penetrating gun using Toku Kou. In addition, the weight fo Chi-To points to a reduction of Chi-Ri weight, which has various sources contradicting each other. Of course, I’ll need to look into Chi-RI more, but something of a 2 ton reduction is not out of question.

I’ll be continuing my Japanese research as I can, to ensure that a distinctively historically accurate and well-balanced Japanese tree can come out. It has been my goal since I started this, and I will certainly work to keep it going.

52 thoughts on “Buff My Tank: Chi-To

  1. Maybe you can convince Wargaming to buff the accuracy or aim time of the STB-1 as well, seeing as it was armed with the a copy of the UK’s Royal Ordnance L7 gun? Just a thought, though.

    • STB doesn’t need buffing, it’s perfectly balanced for its role (close-mid range, harsh terrain brawler). Besides, only the gun breech was from the British L7, the barrel was of indigenous production.

    • Yea don’t buff it… It doesn’t need one , it’s DPM is insane, 2nd best medium, combined with the high mobility, gun depression, tough turret armour, if that that thing had accuracy, it would be OP.

    • heavy tree will either be incomplete (as in end at t6 or something) or it will be full of fakes like german waffletraktor tree is

      • The heavy tree is basely complete, last I heard, they’re just having trouble in finding suitable candidates for tier 5 and 6. We already know which heavy tanks that will fill in for tier 4, 7, and 8 roles: the Type 95 heavy tank will be at tier 4 (just assuming that it is it’s the only one I read about that will probably fit for that tier) and the O-I super heavy tank at tier 7 which is the 100 ton version and tier 8 which will be the 120 ton version (up to 200mm of frontal armor). For tier 9 and 10, well I haven’t heard much about them but last I read they were supposed to be monsters.

  2. Nice!

    I am one of few that REALLY like the Chi-Ri. I have a lot of fun with it, though I do use Deadeye in conjunction :P…
    Small buffs to penetration and a slightly better Chi To would really help the Japanese line :)

      • It’s quite a bit like the old kv-1s: heavy-sized with medium-ish mobility and surprisingly good DPM. The only big difference is you need time to get off three shots, instead of one big derp. On the other hand, an 8 second reload for a three round autoloader is quite nice. If only we could get another 50hp on the engine, it could be one of the best tier vii mediums.

    • I like both the Chi-To and the Chi-Ri, they are both severely underestimated by many.

      @ dai: you are doing a great job. Thumbs up.

  3. Daigensui, do you possibly have a draft of possible Jap TD and arty branches? Also, I heard something about a possible 2nd med line, something in line with German E-series, any word on those?

  4. Very nice post, Dai!

    I personally enjoyed by time in the Chi-To, and the Chi-Ri when using full APCR loadout.

    The 155 pen on the Chi-Ri was awful considering its limited ability to flank, it’s large size, and the mediocre accuracy values. However, I had th luxury of blowing through the Chi-Ri on a X2 EXP weekend, and during the STB-1 On Track event… Money was not an issue with that beast. It was a hit/miss tank, but otherwise not the “worst” tank I have ever played. (IS-8 comes to mind)

    Would like to see some mid-tier buffs for Japan, considering they’re all lackluster.

    • lol what were you smoking. i used the Chi-Ri as a gurilla warfare tank flanking the enemy when i could. if i couldnt i used binocs and sniped using only AP ammo. my average damage is 1600 with the tank. i throughly enjoyed it. now only did it usually hit with 2/3 of its clip on FA i could do it at ranges of 300+ and still pen even tier 9′s.

  5. Interesting article.

    Just minor note of mistypes:
    ” displacement pf 62.27 tons”, “transports were suck while “.

  6. Whta Chi-To and Chi-Nu need is reload buff – while they are already on top, it is still not enough, because of them being so soft, rather TDs than mediums…

    • Personally, I would keep the current Chi-To penetration the same, and use the new information to buff Chi-Ti penetration under “experimental should be receiving the best ammo” thought.

      • if you buff the penetration of normal AP shell to 175 mm, should the premium shell aslo need a buff? Anyway, i think Chi-To need a buff more than Chi-Ri. I’m good with that tank(i was suprise about that my self), manage ~60% winrate before move to STA-1. i think it firepower better than Panther, mobility is not too bad but a buff always wellcomed. Hope that will bring more player to Japan tech tree,
        off topic abit, is the weight of the last Radio on Chi-Ri real? 560 kg seriously?

        • Yes, also the premium round, since they’re all linked with each other..

          Nah, Chi-To is pretty fine as it is right now.

          No, the actual weight was much lighter. As noted in comments below, module weights are semi-historical, semi-arbitrary to ensure that the total combat weight is as close to the actual vehicle.

  7. Hello, Daigensui. Do you know this japanese WGASIA topics?



    Many Japanese player are disgusted with WG.

    • Note: I’ll be talking in English, since non-English posts are frowned upon, and I don’t have Japanese on this computer right now.

      Yes, I know about the first post.

      1) Chi-Nu gun model: Engine limitations, will be fixed one of these days.
      2) Chi-Ri weight: Will be fixed, probably at the same time as the Chi-To weight change.
      3) Chi-To weight: Look above.
      34 Chi-To engine: Complex issue, basically balancing + limiting the number of engine modules for a single tank. WG knows about this, since I originally pushed for it back when submitting the full draft of the Japanese tree.
      5) Type 61 camouflage: Balancing issue, thus not my jurisdiction.
      6) Cooperation: That’s for WGJP to deal with.

      Radio weights: Module weights are semi-historical, semi-arbitrary to ensure that the total combat weight is as close to the actual vehicle. While I appreciate the research, I don’t see it being applied.

  8. とりあえず英語は出来ないので最近の日本のWoT情報について。


    2014年7月にWGJはファインモールド(Finemolds )の鈴木邦宏 社長を訪問し今後の協力について話し合った。

    既に2012年の段階でファインモールドの鈴木邦宏 社長はWGRUに100トン戦車の図面情報などを提供していたと日本の戦車マニアから推測されていたがWGと関わった公式の発表は今回が初。

    • As noted in the article, those penetration pictures are based on steel plate penetration, so not really something to use for WoT.

      Yes, we have data on the 100 ton blueprint. I’ll just say it’s beyond what most people know.

      • 五式75mm戦車砲の貫通威力の話は7月から日本のWikipediaの記載やWoT掲示板でかなり議論されているので当然宮永忠将氏も装甲の件についても理解していると思う。

        • *Shrugs*

          One thing is for sure: Buffing Chi-To’s penetration means nerfing it in other ways, so I rather focus on Chi-Ri.

            • SerB only has influence when he wants to. It’ll likely fall on Storm since he’s now more involved in balancing, if I understand things correctly.

              BTW, make an account on WoT NA, and PM me. Let’s move discussions there, since I would appreciate having a direct line to the Japanese community. Too busy these days to be roaming the net =_=

  9. 2014年8月に国本康文氏が試製九八式中戦車チホ(Type 98 Chi-Ho)に関する新情報を自身の書籍で発表。

    国本戦車塾 九七式戦車系列の戦車砲 チホの謎解明編


      • ネットのcopyじゃなくてWGRUかWGJに購入させないと駄目でしょう。70ページ以上ある書籍で国本康文氏も一部しかネットに載せてない。

        • I know, I’m talking about a hard copy. We bought a few books from the series when researching Otsu, so we know the series has good enough quality for our purposes.

  10. Nice article Dai. Can’t argue with a buffed Chi-Ri.

    Nanashi, thanks for the interesting pictures. 面白い画像、ありがとうございます。As Dai has asked, maybe you will consider signing up in the NA forums? 下のリンクはNAforumsでWoT日本戦車に関して主なディスカッションが今も行っています。それかDaiとPMするでしょうか?http://forum.worldoftanks.com/index.php?/topic/51183-japanese-tank-tree-guns-discussion/#topmost

    • 申し訳ないけれども今回限りの書き込みになるかもしれないので他の場所に移動することはないです。FTRは少なくとも数百人以上の日本人が目を通しているようなので他に凄く詳しい人がいるでしょうし。


  11. i dont see what’s so “fun” about Chi-to, but probably that’s because SEAtards are REALLY STUPID. i get killed more in my chito more than my IS, and i HATE that one more (at least in EU. in SEA it’s actually more playable than the KV3. you need a tank that can haul ass in SEA or you’ll get isolated fast because your noob teammates die faster than a holiday sale rush)

    contact me on steam for futher arguements. my name here is linked to it

  12. 今回のDaigensuiによる日本の装甲板の話には気になる部分があるから指摘してくれと言われたので意見を汲み取って代筆。

    まず五式75mm戦車砲の資料に関してTest plate: steel plate (not RHA)となっているけれど元資料では「鋳鋼板(鋳造鋼板)」 = cast plate。想定敵戦車が鋳造製であることを強調している資料なので、この場合steel plateでは正確ではないと思う。

    >By 1945, much of the HQ interference was either lowered or ignored, with the example of Mitsubishi going its own way with armor plates to finally make RHA of world standard.


    第I種防弾鋼板: 表面硬度320BHN = 均質圧延防弾鋼板
    第II種防弾鋼板: 表面硬度550HV = 浸炭表面硬化防弾鋼板
    第III種防弾鋼板: (表面硬度は第I種と第II種の中間)= 表面硬化防弾鋼板







  13. ~70wr on chito half platooned half solo yolo
    pls buff for wr padding, thanks

    Type 4 Chi-To Japan MT 6 34 70.59%