Japan's phantom multi-turret heavy tank Oi vehicle

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FM44
*This is an image of a plastic model car made by Fine Mold.

This tank has been my most desired Japanese heavy tank for a long time. However, I thought it was a fictional vehicle for a long time, but when I looked into it, I found out that only the body existed, so I decided to write about it.
【Development history】
The Japanese Army planned to develop a super-heavy tank with an unprecedented weight of 150 tons, based on lessons learned from the Nomonhan Incident, which involved armed conflict with Soviet tank units on the Manchuria-Outer Mongolia border between May and September 1939.
This plan is said to have been carried out by Colonel Takeo Iwakata of the Ministry of War on his own initiative, without following any formal procedures.
This super-heavy tank adopted the concept of being disassembled and transported to the rear of the battle line, where it would be assembled and completed, with the dream of creating a mobile fortress of absolute power that would suddenly appear on the battlefield.
The secret name of this vehicle in the army was Oi-sha, which means large car No. 1, and among the employees of Mitsubishi Heavy Industries Tokyo Kiki Seisakusho, which was responsible for the design, it was called Mito-sha, taking the first letter of the company’s name.
【manufacturing】
Production of the oil vehicle began in April 1941, with the basic design being carried out by the Army Headquarters, Mitsubishi Heavy Industries Tokyo Kiki Seisakusho being selected as the manufacturer, and all assembly to be carried out by the Sagami Army Arsenal. However, it was full of problems, such as a reduction in the number of people involved in drafting work and production arrangements not yet completed.Despite these circumstances, Mitsubishi Heavy Industries continued manufacturing and completed the vehicle body. The decision was made to manufacture the turret on March 26, 1942, but it was delayed due to a lack of steel at the arsenal.
【test drive】
It was disassembled and transported from the Mitsubishi Heavy Industries factory to the Sagami Arsenal. Disassembly and transportation took place from May 26 to June 9, 1943, and assembly took place from July 1 to July 20, 1943. From August 1, 1943, running tests of an oil vehicle equipped with a wooden turret began. I was disappointed. Tests revealed that the engine was unreliable, tests were canceled, and the prototype was dismantled in late 1944.
450px-IJA_interior_side_view_schematic_of_the_O-I_super_heavy_tank

​[Performance]
Total length: 10.120 m
Overall width: 4.840 m
Total height: 3.630 m
Weight: Approximately 150 t
Suspension method: Vertical spring
Speed: Standard 18.7 km/h, maximum 29.4 km/h
Main gun: Planned to convert the Type 96 15 howitzer into the main turret.
Secondary armament: One set of 47mm tank guns in two secondary turrets at the front, and one gun mount at the rear equipped with a Type 97 7.7mm vehicle-mounted heavy machine gun converted into a twin machine gun.
Armor: 75+75 mm front, 35+35 mm side [2]
Engine: 2 water-cooled 60-degree V-type 12-cylinder gasoline engines
600hp
300px-IJA_diagram_of_the_O-I_super_heavy_tank_suspension
【photograph】
ss24
It’s the only remaining Oi car track, and it’s apparently very heavy.


Inside view

Prototype weight distribution
!
32
Engineer’s notebook recording the test
sauce

http://www.wakajishi.jp/shiryou.html

Thank you for watching this far

16 Likes

This is not a drawing of the O-I

4 Likes

You’re right....

This is a scale model by Takom which was made after the company acquired the actual O-I blueprints, so it’s pretty much 100% accurate and can be used as a reference image:

edit: Fine Molds is the company with the blueprints

12 Likes

Yeh but the problem with this tank is there’s no visual evidence that the thing was fully made…

2 Likes

As long as major components of it were built, it can be added. The M6A2E1 and TOG II GWK were not fully constructed either yet we have both in-game. Besides, Japan needs everything it can get, regardless of being fully constructed or not.

10 Likes

image
Its this one I guess. There are many images how it suposedly looked like. And all are called O-I basically.

Then there are those :
image
image
image

3 Likes

I mean yes, but the presence of actual test records should be the focal point. For me, that’s compelling evidence on its own. Japanese prototypes, as a trend, suffer from a scarcity of photographs. Take, for instance, post-war designs like sub-i-ii and GSR 105—modern vehicles with no more than three images available online. Now, consider the limitations during World War II when cameras were not widely accessible. Compound that with Japan’s defeat, and it’s clear what happened to most project documents.

8 Likes

the image needs an update. What’s currently there is an outdated artist’s interpretation that predates the unveiling of the actual O-I tank design.

6 Likes

Main difference between that and those are the fact that Both the M6 and the TOG were fully completed and the addon stuff that wasn’t made are minuscule compared to the O-I which, baring the track piece, lacks any visual evidence to back up the claim…

3 Likes

this isn’t some wargaming fake tank just have fun and add it

6 Likes

What is believed to be Oi’s Trackbelt is kept at a Japanese shrine. It was so heavy that he couldn’t lift it by himself.

Spoiler

出典:若獅子神社公式ホームページ
ss24

8 Likes

These are all artist’s impressions of what was originally thought to be a series of Japanese heavy tanks alongside the O-I, but they are all fake and based on rumours and misinformation.

They form the basis for the WoT vehicles ‘O-Ni’ and 'O-Ho".

1 Like

I just hope I can find photos of the O-i body and driving test.
Honestly, there’s too little information…

1 Like

With the way japan was in WW2 and their closely kept archive I doubt you would fine any… if it did exist in any full form…

1 Like

Correction: Fine Molds is currently the sole owner of all the documents and blueprints related to the O-I. Takom’s O-I kit was released a few years after Fine Molds introduced theirs. It’s worth noting that Takom is a Chinese company, while Fine Molds is based in Japan.

By the way, does anyone recall when Mai asserted that Fine Molds not only had access to O-I blueprints and documentation but also possessed a film of the tank during testing? Interestingly, no evidence supporting this claim seems to have surfaced. 🤔

7 Likes

Japan is one of the nations along with Italy and France that could really use more lax enforcement of vehicles like these. Incomplete prototypes, mock-ups and realistic paper vehicles would absolutely help them in areas where they desperately need it.

10 Likes

Oops, wrong company. Thanks for the correction! :)

2 Likes

Maybe because Mai_Waffenträger was a complete Fraut and faked documents and stuff?

6 Likes