Type 4 Chi-To Prototype I

Do you want to see the Chi-To (57) being implemented ?
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Type 4 Chi-To (57), Medium Tank, Japan, Rank 2

This is a suggestion for the early prototype of the Type 4 Chi-To with a different turret and equipped with a 57mm tank gun.

The Chi-To’s journey began in 1941, conceived as the successor to the Type 1 Chi-He. Initially, the specifications laid out in early 1942 mirrored its predecessor— a 20-ton tank with 50mm armor, 40 kph top speed, and the Type 1 47mm tank gun. However, enhancements were introduced, including a coaxial machine gun, an electric turret drive, synchronous mesh transmission, and hydraulic steering. By August 1942, plans shifted to incorporate a more formidable high-velocity 57mm gun as an alternative. Yet, by January 1943, the 20-ton design was deemed obsolete.

In a strategic move, development transitioned in February to a larger medium tank, now a 25-ton behemoth boasting 75mm armor and a 57mm gun. The evolving landscape of tank warfare prompted another shift later in the year. A research policy in July birthed a 35-ton medium tank armed with a cutting-edge 75mm tank gun—this became the Chi-Ri. In contrast, the 25-ton design, now the Chi-To, was destined for auxiliary support duty.

The Chi-To’s primary armament was the Experimental 5.7 cm Tank Gun Maru-Shin, derived from the towed Experimental Motorized 57mm Gun, specifically the Kō variant tested on a Ho-I tank. The Maru-Shin gun aimed for a planned muzzle velocity of 810 m/s and boasted the capability to fire APHE and HE shells. Development was slated for completion by March 1945. However, by August 1943, records hinted at the potential transition from the 57mm gun to the 75mm gun planned for the Chi-Ri, acknowledging the encroaching obsolescence of the former.

Completion and Trials

In March 1944, the first prototype of the 57mm Maru-Shin gun saw the light of day, closely followed by the inaugural Chi-To prototype in May 1944. The turret bore a striking resemblance to the Type 2 Ho-I’s, albeit fortified with 75mm of frontal armor. Notably smaller and lighter than its successor’s cast turret, this initial iteration showcased a promising direction. The hull, boasting 75mm of frontal armor, marked a considerable size augmentation, measuring 6.34 meters in length, 2.87 meters in width, and 2.67 meters in height. Weighing in at approximately 24 tons, the Chi-To prototype slightly undercut the original planned weight.

Powering this armored beast was the 412-horsepower Mitsubishi AL air-cooled diesel engine. Mobility trials unfolded from May 16th to 20th, spanning the 4th Army Technical Research Institute and the Sagami Proving Grounds. The chassis earned accolades for its overall performance, achieving a commendable on-road top speed of 46 kilometers per hour. The Mitsubishi engine proved its mettle, excelling in cooling, and the hydraulic steering mechanism and synchro-mesh transmission garnered high praise for their user-friendly operation. A display test for the general manager on the 25th further validated the positive results.

On May 29th, the Experimental 5.7 cm Tank Gun Maru-Shin took its place in the turret, unleashing 89 rounds in testing. Challenges emerged as firing loosened five rivets in the turret, impeding rotation on inclined surfaces. Additionally, the 5.7 cm gun fell short of its planned muzzle velocity, reaching only 798 meters per second instead of the targeted 810 meters per second. Even if the gun had hit the intended velocity, its fate as a contender was questionable. Consequently, the 57mm Chi-To met its demise, relegated to the annals of canceled projects.


The Chi-To’s 57mm Maru-Shin gun had its roots in the Experimental Motorized 57mm Gun, serving as its predecessor.

The fate of the first Chi-To prototype remains shrouded in uncertainty. Production reports from December 1944 classify it as “unfinished,” leaving room for speculation that the 57mm Chi-To might not have been deemed complete during its May 1944 trials. If this holds true, it suggests the possibility that the subsequent 75mm Chi-To prototype, finalized in February 1945, might have repurposed the hull of the 57mm Chi-To, integrating it with the larger cast turret and 75mm gun. Alternatively, if the “unfinished” designation is a production report error, the 57mm Chi-To prototype could have been either preserved or dismantled, while the new 75mm Chi-To prototype was constructed from the ground up.


General specifications:

  • Hull Armor: 75/35/20

  • Turret Armor: 75/50/50

  • Crew: 5 (Gunner, Loader, Commander, Driver & Radio Operator).

  • Mass: ~24 tons (loaded)

  • Engine: Mitsubishi AL (Type 4) Engine, Type: 4-stroke V12 air-cooled diesel 412 horsepower at 1,800 rpm

  • Max Forward speed: On-road: 46 km/h, Cruise: 31 km/h

  • Transmission: Type: Synchro-mesh, Gears: 4 forward, 1 reverse

  • Steering: Hydraulically Assisted

  • Main Armament: Experimental 5.7cm tank gun Shin-Maru

  • Secondary Armament: 2x Type 97 7.7mm Heavy Tank Machine Gun [Hull mounted & Roof mounted]


The primary armor-piercing ammunition for the 57mm Shin-Maru gun was the experimental Type 1 APHE. In contrast to the older Type 92 APHE, this round had a slightly increased weight of 2.7 kilograms but featured a significantly reduced explosive mass of approximately 30 grams. The explosive content was likely RDX, in line with other Japanese Type 1 APHE rounds.

Type 1 57mm APHE

  • Projectile mass of 2.7 kilograms
  • Explosive mass of ~30 grams
  • Explosive type of 90% RDX and 10% Paraffin
  • Muzzle velocity: Planned: 810 m/s. Actual result: 798 m/s

This gun is also competible with ammunition used by the older Type 97 57mm tank gun found on the Chi-Ha which fired Type 92 APHE and Type 3 HEAT rounds.


Sources

All credit goes to @Tasty95215 for the sources and original suggestion !

Chi-To 57mm - the first Chi-To prototype - Passed for Consideration - War Thunder - Official Forum

12 Likes

This would be a really fun intermediate tank between the Chi-Nu and Chi-To. +1

5 Likes

+1 And if I’m not mistaken, there was also a project to equip the Ho-I with the same gun?

3 Likes

Yes, the 57mm gun was equipped in the Ho-I first before they moved on to the Chi-To.
I might plan to re-suggest the Ho-I later.

4 Likes

One thing i forgot to mention that was brought up in the original suggestion.
The olderr 57mm shells fired by the Type 97 57mm gun found on Type 89 I-Go or Chi-Ha etc should be competible to the new 57mm gun.

This included Type 92 APHE and Type 3 HEAT with 55mm pen at all range.
I’m not sure how much imporvement the Type 92 would have when fired from the experimental 57mm gun.

This thread included all the Japanese tank guns and ammunition:

1 Like

are there any photos of this vehicle? +1 either way, just wondering if there are some

1 Like

To be even more precise, the Ho-I initially supported a short-barreled 75 mm and a long-barreled 57 mm gun, which could be changed directly in the field depending on the mission, without changing the turret design, to suit current missions. However, the project for a 57 mm long-barrel tank gun was canceled along with the carriage version, and therefore this design feature was not used in practice.

I’m sure this is submerged in the lake, so I’m happy to see it in-game.

2 Likes

+1

1 Like

Do you have any more information on the transmission (specific gear ratios and top speeds)? And is it the same transmission as used on the other Chi-Tos, maybe even the Chi-He?

+1

1 Like

I took the specifications from the original suggestion but apparently it is just the same Synchromesh transmission made for the Type 4 medium tank so it is nothing that we don’t already have in the game.

Fun facts: This transmission and steering system were later used as reference for the ST-A prototype and eventually the Type 61 tanks.

Type 4 is the… Chi-He, yes?

I’m asking because it doesn’t seem like the transmission on these tanks is correct in game.

Type 1 = Chi-He
Type 2 = Ho-i
Type 3 = Chi-Nu
Type 4 = Chi-To
Type 5 = Chi-Ri

1 Like

Ah, ok, but in game the Chi-He all the way to the Chi-Ri have extremely similar transmissions with some slight tweaking on the last gear to make the top speed slower or higher.

Chi-He and Chi-Ri transmission

This is the Chi-He’s transmission in WarThunder.
image

This is the Chi-Ri’s.
image

Are the Japanese WWII medium transmissions just so inconsistent in game?
Left is what’s claimed they had and right is what they have in game.
Chi-Ha - old type - 4+1 - 4+1
Chi-He - old type - 4+1 - 8+2
Chi-To - syncro - 4+1 - 8+2
Chi-Ri - syncro - 4+1 - 8+2

Chi-Ha had high and low ratios, so either they forgot that or it is something else.

Here’s the thing: since each gear gets associated to a “high” and “low” gear, you can effectively pair up all the obtained gear ratios. If you were to divide one of the “high” gears by associated “low” gear pair, you’d get a constant value.

Let’s take a look back at the Chi-He and Chi-Ri in-game transmission.
Since it’s only 1 reverse gear on the main gearbox, that means we can just divide the 2 reverse gears to obtain the “constant” value we are searching for. 8.35 (low gear) divided by 5.35 (high gear) gives us 1.561 (ratio difference between high gear and low gear), approximately.

The problem is that this value never repeats itself. Take the very last gear, which is just 1 (guaranteed to be a high gear), and multiply it by 1.561, which, well, gives a gear ratio of 1.561, except this gear ratio is nowhere to be found on the transmission.

In short, the number of gears is correct… but there is no way that the gears themselves are correct. This is pretty obvious if you just look at the gear ratios themselves with no math, there’s no way that all the forward gears would be perfect multiples of 0.5.

I think they’ve done so with multiple vehicles and I have no idea why. The Strv 74 is another example. It had two different gearboxes for its variants, either 2+4 or 1+5. The one in the game has 1+6 lol.

I can understand finding info on gear ratios might be difficult for some vehicles, but the amount of gears is one of the first things you tend to find when looking up the automotive specs.

1 Like

The one that is was a 75mm

So all Chi-Ha variants should have 8+2 as well?