ground vehicles IJN 12cm SPG

[Jager49283 124]

IJN 12cm SPG

 

History:
With the increasing loss of its ships, the Japanese navy was more and more concerned about their ground and defensive weapons. Some naval guns were converted to howitzers and anti-tank weapons. Some were even meant to be placed on chassis of obsolete tanks for greater mobility.
One of such improvised SPG's projects was a 12cm naval gun mounted on a "Type 97 Chi-Ha" chassis. Though it's official designation is unknown, it is now commonly referred to as the "Type 97 Chi-Ha 120mm Long gun" for disambiguation with the better short gun variant built on the same chassis. Other names include: "IJN 12cm SPG" or "Naval SPG". It's crew members simply called the machine "self-propelled gun".
A prototype was completed by the end of the war. Various test were also conducted and even orders for mass-production were given(probably conversions from "Chi-Ha" tanks already in service). The "Chi-Ha" used as the base belonged to the IJA 6th Division and was stationed at the Tateyama Navy Artillery School in January 1945. In April 20, the 12cm Type 10 gun was place on the hull. After the capitulation of Japan the experimental SPG was discovered by the US army in Yokohara. It's fate is unknown.

 

Technical Description:
It was intended to rearm the "Chi-Ha" with the combat proven 12cm Type 10 Dual-Purpose gun. To make this possible, the turret had been removed and the gun itself was modified to fit to the chassis. During some firings in April 1945, it showed a very good hit rate at about 1500m. This was due to the fact that a new sighting system developed by "Tokyo Keiki" had been equipped.
The gun had mostly retained it's original design. It was of monobloc construction with right hand rifling. The elevating handwheel was on the right side of the gunner's seat, while the traversing wheel was on the left. The gun had a hydrospring type recoil mechanism: the 2 outside cylinders housing the counter-recoil springs, and the center cylinder the hydraulic mechanism.
The gun was 360° traversable. But as the "Chi-ha" chassis was too small and lightweight for the 8t gun, shooting sideways was be very problematic (the recoil would simply kick the gun of the hull). Even firing in the aft and fore directions would greatly rock the vehicle. Also, the on-board machine gun was removed and the port sealed shut. The crew received additional weapons instead.
This SPG was not a vehicle intended for anti-air or indirect-fire use. The maximum elevation/depression was +20°/-10°. Also the crew had little to no protection, not even a gun shield. According to the former commander's testimony, the crew was supposed to make use of "Shoot-and-scoot" tactics in battle. As the original "Chi-Ha" chassis was to narrow, some additional plates were placed on the top part to give at least some comfort to the crew members.
Even though the SPG was obviously designed to fight tanks, it is unknown if any AP rounds were ever manufactured for the weapon. The standard ammunition of the Type 10 were H.E. and Shrapnel rounds that weighed 20,7kg, with a complete round weighting 32,4kg. The ammunition was never stored inside the hull, instead it was loaded from a special transport located/towed behind/by the vehicle or from a predetermined location near the SPG. Maybe, ammo containers were also placed somewhere in the aft part of the hull.
The chassis was under high pressure because of the overweight (estimated to be more than 20t). This led to frequent transmission failures, especially after firing. Moreover, as the gun was biased to the right from the center, the hull was also inclined to the right. Under such pressure the suspension broke very often.
According to the former crew members, the maximum speed was around 25km/h. Based on this information, the engine is presumed to be the standard "Chi-Ha" 170hp(127 kW) "Mitsubishi SA12200VD".

 

Technical Specifications:
Crew                                           5
Weight                                        around 21 tons
Length (gun forward)                  ?
Hull length                                   5,5m
Width                                          2,33m
Height                                         ?
Main armament                           12cm Type 10
Muzzle velocity                            825m/s    
Secondary armament                 none
Projectile weight                         32,4kg
Maximum firing range                 3000m
Maximum rate of fire                   around 5-9 rpm (maybe)
Elevation range                          -10° / +20°
Traverse range                          360°
Ammunition carried                    ?
Machine gun ammo                   none
Powerplant                                170hp(127 kW) "Mitsubishi SA12200VD
Power-to-weight                        around 8 hp/t         
Maximum road speed                around 25 km/h

 

Spoiler

 

Sources:

Spoiler

https://ja.wikipedia.org/wiki/海軍十二糎自走砲
https://archive.org/stream/CatalogOfEnemyOrdnanceMateriel#page/n155/mode/2up
http://ost-front.ru/2015/07/21/ijn-12-cm-spg/
https://en.wikipedia.org/wiki/Type_97_ShinHoTo_Chi-Ha

 

 

Edited June 24, 2017 by Jager49283

[SAUBER_KH7 3,326]

Open for Discussion.

[Delta_48 471]

Would be a decent tier III premium +1

[Results45 2,200]

Cool. The Imperial Samurai never have enough tanks with which to employ their bush tactics  

[Nuclear_Frog 363]

This would be a good addition. Japan needs more variety of vehicles, especially ones with bigger guns that can effectively knock out heavier tanks and tank destroyers. Right now you can only compose a very one sided team of tanks. Definitely for the regular tree!

 

Btw. How effective is the ammo against tanks?

Edited May 30, 2017 by Nuclear_Frog

[CaID 8,996]

i dont think it carried ammo at all, an ammo truck must had fallowed those Artillery. but a little rack could be added with 2 or 3 of those ammo box.

[Admiral_Aruon 2,264]

reminds me of the FV4005 Stage I.

 

i'll +1 it.

[Hamaguchi 134]

It was a prototype to supposedly provide a fast coast covering from eminent naval invasions...

 

There's a non-built 149mm type 5 version too.

[DebtlessWalnut 675]

More info: https://www.reddit.com/r/Warthunder/comments/6d5hhj/naval_long_12cm_chiha_experimental/

[Optical_Ilyushin 5,554]

+1, love it

[ZapGun 20]

I support the addition, but you need more information since there are a lot of numbers missing in your suggestions. 

 

[WiseMinerva 454]

This would be a good addition to Japanese tree

 

+1 support

[RememberRoute23 177]

+1 Would make a great secondary artillery vehicle in my SNLF line up along side the 120mm Short Gun Chi-Ha

[Jager49283 124]

Topic updated... actually, it has been completely rewritten.

 

 

 

[Arin171 205]

+1

[AtomicPope 3,953]

I think we need to know if ht actually carried ammo on it's own and if the crew could stay on the vehicle to use it(the vehicle looks like the crew needs to dismount to operate it properly).

[Spartan_warrior 4]

very nice gun

[The_Strafer 131]

Would fit nicely after the Na-To due to the gun. +1

[Jager49283 124]

On 6/22/2017 at 4:30 AM, AtomicPope said:

I think we need to know if ht actually carried ammo on it's own and if the crew could stay on the vehicle to use it(the vehicle looks like the crew needs to dismount to operate it properly).

As stated in my sources, it could not carry any ammo. Instead a special trailer had to be towed by the vehicle. Such ammunition transports were usually towed by tankettes ot trucks. How the developers are going to implement this is unknown to me, they might as well glue some ammo crates on the top.

 

Indeed, the crew (5 men) would have not been able to operate the SPG properly, the 2 loaders probably were to get off, or at least hold on to something. Only fixing or "burying" the vehicle would solve this issue. Than again, it's up to the developers.

 

[Optical_Ilyushin 5,554]

On 6/23/2017 at 10:03 PM, Jager49283 said:

As stated in my sources, it could not carry any ammo. Instead a special trailer had to be towed by the vehicle. Such ammunition transports were usually towed by tankettes ot trucks. How the developers are going to implement this is unknown to me, they might as well glue some ammo crates on the top.

 

Indeed, the crew (5 men) would have not been able to operate the SPG properly, the 2 loaders probably were to get off, or at least hold on to something. Only fixing or "burying" the vehicle would solve this issue. Than again, it's up to the developers.

 

 

well given the awkward nature of some of the tanks in the game to load, I think it might be a good idea to add some sort of attachable ammo truck.

[HerrSektor 3,840]

Gaijin needs to add this at Tier IV with his correct rounds, not like the Navy-Ha that's literally only fires HE when it could fire APHE with huge TNTeq load at 60mm pen and HEAT rounds that could pierce upto 150mm...

[Results45 2,200]

4 hours ago, zSektor92 said:

Gaijin needs to add this at Tier IV with his correct rounds, not like the Navy-Ha that's literally only fires HE when it could fire APHE with huge TNTeq load at 60mm pen and HEAT rounds that could pierce upto 150mm...

 

It's called the Derp-Ha. 

[The_Strafer 131]

5 hours ago, zSektor92 said:

Gaijin needs to add this at Tier IV with his correct rounds, not like the Navy-Ha that's literally only fires HE when it could fire APHE with huge TNTeq load at 60mm pen and HEAT rounds that could pierce upto 150mm...

Wait what...

[Admiral_Aruon 2,264]

7 hours ago, Optical_Ilyushin said:

well given the awkward nature of some of the tanks in the game to load, I think it might be a good idea to add some sort of attachable ammo truck.

 

i agree. either a little towed ammo cart, or either an ammo crate(s) by the loader and a long-ish reload

[ZapGun 20]

32 minutes ago, Admiral_Aruon said:

 

i agree. either a little towed ammo cart, or either an ammo crate(s) by the loader and a long-ish reload

Well...we all know how good the towing mechanics work. Iam just saying that the game engine couldn't handle this vehicle with an ammo cart attached to it