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[25/05/2021] [2.6.0.18] M47 Incorrect Gun Depression


# Circuit

2.6.0.18

 

# Affected Vehicles

M47 (Japan)

M47 (Germany)

M47 (USA)

 

# Detailed Description

Current the M47 in game has -5° of gun depression and +19° of gun elevation for its elevation limits. In reality however, this is -10° and +19°, While values of -5°/+19° is mentioned in one document, its incorrect and misleading for reasons i will explain.

Screenshots of the Vehicles in game (only using the Japanese one here)

ARXeH8j.png


 

First thing to establish here is that the present -5°/+19° values comes from TM 9-718A “90-MM GUN TANK M47” published January 1952. which on page 19 gives these values

bazQKLG.png


 

While this is technically correct, its invalid and misleading for the tanks the troops actually got, but to explain this i should give some history on the M47. Now for simplicity, i am going to be citing R.P Hunnicutts book “Patton. A History of the American Main Battle Tank” from 1984, as references for the M47 program and history because no other book breaks down the development program so well.

For a quick abbreviated history, when the Korean War broke out, the US Army looked at it with concern it might spread into another global conflict, at this time the Medium Tank T42 was in testing, this program wasn't going so well and needed more time, the Army however was very eager for a new medium tank in the shortest time, and so expedited the T42 program by instead mating the turret to a known working chassis, the M46s. A short test program of the M46E1 later, it was approved for production in a slightly modified form as the M47, with production starting in June 1951.

Following this, the first tank was delivered July 1951 for trials, these tanks were then in trials from August 1951 to August 1952.

wRmfobE.png

^page 55 mentioning test program ran until August 1952.


 

The significance here is, the M47 was still in trials when the original manual was published in January 1952, and following the end of trials in August 1952 as mentioned on page 58, fifteen modifications were considered essential before the tanks could be issued to troops. For what is relevant here is that this included modifications to the elevation system.

D7Ua37g.png

^ Patton page 58


 

Hunnicutt further writes these tanks were only issued to troops following these modifications, being first sent to Europe, and the first photographs of the M47 with troops in Europe are dated to October 1952, supporting the notion troops didn't get these tanks until October 1952, is TM 9-1730E (described later)

4MMpiqg.png

^ Patton page 64.

In October 1952 a large new manual describing the turret hydraulic systems Technical Manual TM 9-1730E “Hydraulic Turret-Traversing and Gun Elevation System for 76-mm GUN TANK T41E1 AND 90-mm. GUN TANK M47” October 1952 was issued out, which on page 9 gives that the now current elevation and depression limits are now -10° and +19°

2rW5gTg.png


 

This can be confirmed to have become the standard on M47s issued since the later M47 manual, TM 9-2350-200-12 “Operational and Organizational Maintenance 90-mm GUN FULL TRACKED COMBAT TANK M47” October 1958 also gives the limits as -10° and +19° on page 26

https://i.imgur.com/P9A14Qx.png


 

To show that changes happened to the set ups without going into many small nuances and over complicating this report, i have decided to just include diagrams of the turret electrical systems for evidence of the changes as this shows one that the wiring changed, and secondly it mentions a few components not present in the January 1952 manual.


 

January 1952 TM 9-718As electrical diagram (pages 500-501), of particular interest here is that the Army unit that received these tanks and this manual wrote that “Old Style Do Not Use” supporting the notion that units where not using the original turret systems.

https://i.imgur.com/gycPSLt.png


 

October 1958 TM 9-2350-200-12s electrical diagram one can see the added systems to the turret in the form of the elevation and traverse tracking motors, and the pulsing relay for example, in addition to general wiring changes.

https://i.imgur.com/jbo5X2h.jpg


 

October 1952 TM 9-1730E has many diagrams, however i am just going to include the pulse relay system, since it is a system added with the changes, and it also shows other aforementioned added components such as the traversing and elevating signal motors, and the aforementioned pulse relay box

nMmpPEn.png


 

Indeed it would appear that no M47s where issued to troops to the original specification, and that they where indeed modified to the new standard, the M47 in game then being akin to the trials configuration for this tank and not its actual in service configuration.


 

#Steps to reproduce

look at any 90mm M47 in xray


 

#Suggest solution

Increase the M47s gun depression from -5° to -10°


 

# Additional Information

TM 9-718A “90-MM GUN TANK M47” January 1952

https://i.imgur.com/the1Gh6.png

TM 9-1730E “Hydraulic Turret-Traversing and Gun Elevation System for 76-mm GUN TANK T41E1 AND 90-mm. GUN TANK M47” October 1952

https://i.imgur.com/lCy1gdb.png

TM 9-2350-200-12 “Operational and Organizational Maintenance 90-mm GUN FULL TRACKED COMBAT TANK M47” October 1958

https://i.imgur.com/VTdiHcD.png

R.P Hunnicutt “Patton. A History of the American Main Battle Tank” 1984

https://i.imgur.com/WcSrnSL.png

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Hi,

Thanks for the report.

I'll read, investigate, test if needed and get back to you soon.

 

Regards, Optical Ilyushin

Technical Moderation Team

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Hi

 

Thank you for your interest and help improving the game.

 

Your information has been forwarded to the Developers for their consideration. If there is anything further regarding this report a Technical Moderator will contact you.

 

Thank you again for your support.

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  • Optical_Ilyushin changed the title to [25/05/2021] [2.6.0.18] M47 Incorrect Gun Depression
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