Type 56 105mm self propelled gun "SY" - a Japanese take on the M37

[Tasty95215 2,099]

 

History and Development:

In 1954, the Japanese Ground Self-Defense Force was created. However, all of their equipment at the time was towed, hindering their mobility. As such, the first vehicle that they designed was something that could carry the weapons they had at the time; this vehicle was the Type 56 105mm self-propelled gun. It was designated the SY, which followed the naming convention the JGSDF used between the 1950's through 1970's for tracked prototype vehicles. The S stood for Soki (tracked) while the Y signified which project the prototype was a part of.

Spoiler

https://twitter.com/type3fighter/status/1265460148471885826

 

SA: Amphibious Mud Working vehicle

SB: Type 67 Armored Vehicle-Launched Bridge

SD: Type 67 Armored Work vehicle

SR: Type 70 Tank Recovery vehicle

SRB: Type 78 Tank Recovery vehicle

SS: Type 60 Self-Propelled Recoilless Gun

ST(A): Type 61 tank

STB: Type 74 tank

SU: Type 60 Armored Personnel Carrier
SUB: Type 73 Armored Personnel Carrier

SV: Type 60 81mm Self-Propelled Mortar
SW: Prototype Tracked Land Mine Disposal vehicle (never received full designation)

SX: Type 60 107mm Self-Propelled Mortar
SY: Type 56 105mm Self-Propelled Howitzer
SZ: Type 56 Special Transport vehicle

 

 

The SY's design was strongly influenced by the American M37 self-propelled gun. Both were SPG's based on the chassis of the M24 Chaffee and used the American M2A1 105mm howitzer. Both also had an M2 browning .50 cal machine gun placed at the front right of the vehicle. The main difference between them was that the SY had a fully enclosed fighting compartment, which would better help protect the crew. Another difference was the gun mount around the 105mm howitzer - while this let the SY retain the same accuracy and rate of fire as the original howitzer, the elevations was limited to only 35° - very low for an SPG. The SY was also slightly smaller than the M37 in all dimensions.

 

The American M37 SPG, which was first built in 1945.

 

The main reason that the Japanese decided to develop the SY as opposed to just getting the M37 sent over was over concerns about the mobility. The M37, despite sharing the same chassis and engines as the Chaffee, was more sluggish due to its increased weight. The goal of the SY was to have an SPG that had the same mobility that the Chaffee had. As such, the SY had a modified transmission and a Mitsubishi diesel engine with 230 horsepower, slightly less compared to the Chaffee's twin petrol Cadillac engines with 296 total horsepower. The worse power-to-weight ratio was supposed to be compensated with a "115TC-Ms200" transmission with a torque converter. 

 

 

The design of the SY was finalized in 1957, and the first prototype was completed in January 1958. Pitching tests were held in Misaka Pass and sand mobility tests were held on the coast of Chigasaki.

 

 

These first revealed that the diesel engine overheated, and so the SY was sent back to get that fixed. The following trials and examinations were conducted the next year, with the resulting mileages exceeding 6000 kilometers. It was found that the 115TC-Ms200 transmission had very poor performance when the engine had low torque. This lead to the transmission getting replaced with a hydromatic automatic transmission as well as further modifications to the auxiliary transmission. Even with these modifications, the project ended up getting cancelled and the JGSDF ended up adopting the M44 and M52 self-propelled guns instead. The next self-propelled gun that the JGSDF developed would be the Type 74 105mm SPG, which started its development in 1967.

 

During tests at Misaka Pass, a bus tried to overtake the SY, resulting in it crashing

 

Performance and Specifications:

• Weight: 20 tons
• Length: 4.860 meters (not including MG)
• Width: 2.844 meters
• Height: 2.340 meters
• Engine model: Mitsubishi 8HA21WT, Air cooled V8 Diesel with turbo-charger
• Engine power: 230 horsepower total
• Power-to-weight ratio: 11.5 hp/ton
• Top speed: 45 km/h
• Armor: Unknown (probably the same as the M37, with 1/2 inch on both the chassis and the superstructure)
• Crew: 7
• Armament: M2A1 105mm Howitzer, secondary M2 Browning .50 caliber machine gun
• Traverse angles:
  • Elevation: +35°
  • Depession: ?
  • Horizontal: +20° both left and right

 

The SY has the same gun as the M4A3 105mm Sherman, the American 105mm howitzer. Although their variants differed - the Sherman used the M4 variant while the SY had a modified M2A1 variant - they should have the same performance. The SY would be capable of firing the following shells in War Thunder:

• M1 HE shell , with 26mm of penetration and 2180 grams of TNT or Composition B
• M67 HEAT shell , with 130mm of penetration
• M84 Smoke shell , deploying a smoke cloud for 25 seconds

 

M2A1 Howitzer with modified mount:

Spoiler

 

Engine, transmission and torque converter diagram:

Spoiler

 

 

Technical drawings and specifications:

Spoiler

 

Position in War Thunder :

While some specifications are still unknown, we can approximate where the SY would be in War Thunder compared to similar vehicles - namely the M4A3 105mm and the StuH 42 G. The SY has much less armor compared to both, and the StuH has its APHE shells and the Sherman has a turret. Mobility-wise, they're about the same - the SY has a slightly better top speed but slightly worse power-to-weight ratio. The SY's only possible advantage over the both of them is  in its reload speed - the SY has a maximum of 7 crew members, which would include at least 2 gunners and loaders, lowering the reload speed compared to the other two vehicles.

 

In Realistic Battles, the M4 105mm is BR 2.7 while the StuH is BR 3.0, so it's likely that the SY would have about the same BR. While this would be pretty anachronistic compared to most other vehicles at that BR, there's already a precedent for post-war vehicles at low BR's (see the Sav m/43 (1946) or the Pvkv II). Furthermore, it's not like the SY would be overpowered in any way or bring any advanced technologies to that BR.

 

As far as whether it should be a premium or a tech tree vehicle, I could see it being either way. On one hand, the SY wasn't built until 1958, more than a decade after all the other Japanese tanks around that BR, and it would be seriously disconnected from the rest of the Japanese tech tree. On the other hand, its base, the M24 Chaffee, is already present within the tech tree so it wouldn't be too out there. There's still a BR gap between the Ho-Ni III and the Na-To too.

 

Sources:

• Post-War Japanese Tank Development History-From the "Tokusha" to the Type 90, published 2002 (戦後日本の戦車開発史―特車から90式戦車へ 単行本 – 2002/8)
• Grand Power magazine, November 2003 Issue "Equipment Vehicle of the Ground Self Defense Force Vol.1 '60's Edition" (this title was Google-translated) (ガリレオ出版　グランドパワー 2003年11月号別冊 「陸上自衛隊の装備車両 Vol.1 '60年代編」)

• Tomio Hara, Akira Takeuchi, 1961 ""Japanese Tank and Fighting Vehicles"" Shuppan Kyodo Sha

  Vol.1 page 158-159

• https://bulletpicker.com/_usd.html (Information on compatible shells)

• https://ikazuchisen.wordpress.com/type-56-105mm-experimental-spg-post-war-jsdf/
• https://ja.wikipedia.org/wiki/試製56式105mm自走砲
• http://www.tankarchives.ca/2017/07/m24-chaffee-test-drive-at-end-of-lend.html (Information on Chaffee engine power)

Edited October 24, 2021 by Tasty95215
higher-res pics

[leroyonly 4,310]

Open for discussion. 

 

But i would suggest that you add the armor vallues for the chassis during the lack of solid figures for the casemate's armor.

[aizenns 3,590]

I find some data about "SY".

• Weight: 20t
• Crew: 7~3
• Size
  • Length: 4.860m
  • Width: 2.840m
  • Height: 2.340m
• Engine
  • Type: Mitsubishi 8HA, Air cooled V8 Diesel with turbo-charger
  • Power/rpm: 230HP/?
• Weapon
  • Cannon: 105mm howitzer M2A1 ×1
  • Machine gun: 12.7mm machine gun ×1
• Max Speed: 45km/h

Quote

 

Sorce

Tomio Hara, Akira Takeuchi, 1961 ""Japanese Tank and Fighting Vehicles"" Shuppan Kyodo Sha

Vol.1 page 158-159

 

 

Edited June 2, 2018 by aizenns
Fix typo

[Tasty95215 2,099]

On 01/06/2018 at 05:16, aizenns said:

I find some data about "SY".

 

Thank you! This is incredibly helpful. A part of me even wants to update the SY's Japanese Wikipedia page with that information, though I'm still only just learning Japanese.

 

Looking at that engine, I can only assume that there were two of those diesel engines, as the Chaffee had two engines as well. This would bring the total horsepower to 460, higher than the Chaffee and M37's 440 horsepower. The top speed is less than I expected (the M37's is listed as being the same as the Chaffee's at 56 kph), but the power to weight ratio would be better than the M37's.

 

Also, I have a question about the howitzer - in the page that's shown, it mentions that the howitzer used was the M2A1. However, in the translation that was posted it says that it used the M2A2 instead. Was the M2A2 just a typo?

Edited April 17, 2020 by Tasty95215
That part's completely inaccurate; ignore that

[aizenns 3,590]

6 hours ago, Tasty95215 said:

Also, I have a question about the howitzer - in the page that's shown, it mentions that the howitzer used was the M2A1. However, in the translation that was posted it says that it used the M2A2 instead. Was the M2A2 just a typo?

Yes, it’s typo, sorry.

[WayOfTheWolk 1,573]

+1

The Japanese require more love in honor of the emperor.

[Milocat 4,848]

+1!  The Japanese could use more vehicles and this would be a good addition!

[BrentD15@psn 1,116]

Yes, more please!

[super_cacti 1,071]

More Derp guns please! 

[copeypastow 1]

This vehicle would provide some interesting gameplay in the lower ranks due to its mobility and gun. I support this idea!

[Fireraid233 4,274]

Please add this tanks it looks so cool and derpy.

[Graxum 332]

wow, not a 172350189234710928419523th copy of a M48/Leo?!? Heresy!

[Wolf_89 2,524]

Yes pls. Has same ammo as M4A3 105 Sherman.

[Tasty95215 2,099]

Sorry, I've had to make a pretty big correction on this - for some reason I thought the Chaffee's engines were 220 horsepower each, instead of 220 horsepower total (296 maximum power). As such, I completely overestimated the SY's own mobility here. This is now corrected and clarified, along with updating some old dead wiki links and the "Position in War Thunder" section.

[Wiggly_Armed_Man 2,383]

On 14/04/2020 at 22:54, Tasty95215 said:

Sorry, I've had to make a pretty big correction on this - for some reason I thought the Chaffee's engines were 220 horsepower each, instead of 220 horsepower total (296 maximum power). As such, I completely overestimated the SY's own mobility here. This is now corrected and clarified, along with updating some old dead wiki links and the "Position in War Thunder" section.

Thanks for all of your work in it.

[Borotovas 4,500]

+1

[ForeverAloneRage 130]

From 

[島風 2,396]

Kinda Iffy On The Addition Of Post War Vehicles Under 6.7 (Regardless Of Performance Or Nation) But Would Want To See This Vehicle Regardless.

It's Just Weird To Throw This In At 3.0-3.7 Next To Chi-Nu's & Ho-Ni's.

But Then Again, You Can Argue That The M24 Is In That Exact Line-Up... But Then Again These Concerns Are Soley Mine.

Edited December 5, 2020 by ShimakazeChan

[Solarmod 1,203]

I'd love to see this in game, despite it being a post-war development.

[Tasty95215 2,099]

Short video on the Type 56, talking about the vehicle's characteristics and showing more pictures and diagrams. It's by https://twitter.com/type3fighter; I'll add the photos to the OP when the maker posts them on Twitter.

 

Edited January 26, 2021 by Tasty95215

[_N4MELESS_ 2,972]

Yes, but currently i'm not looking forward anymore SPGs for Japan at the moment, seems like we are getting a little bit too many of them recently.

[Tasty95215 2,099]

Quote

Yes, but currently i'm not looking forward anymore SPGs for Japan at the moment, seems like we are getting a little bit too many of them recently.

 

That's fair. Don't blame me though, Gaijin's the one deciding on which vehicles they want to add.

 

Anyways, I'm adding some more photos and information to the OP this time some specifics on the gun angles, mobility and history (including why the Type 56 ended up getting canceled). This is probably all the information available at the moment - thanks again to https://twitter.com/type3fighter for posting about this obscure prototype.

 

Also, kinda funny story - at one point during the Type 56's mobility trials a bus tried to overtake it on the road's shoulder and ended up crashing:

 

 

More photos:

Spoiler

 

 

 

 

 

 

Edited March 21, 2021 by Tasty95215

[DukeLongTree 11]

we need another japanese durp gun 

[_N4MELESS_ 2,972]

Slightly better quality images:

[hienapunk 1,064]

On 24/10/2021 at 08:22, I_NAMELESS_I said:

That closed roof is enough to differentuate it from the American design that inspired it.

 

Though to be honest I'd still vote for it even if it was an exact copy. Japan's tree is really empty, especially in the early cold war era.