Wednesday, 15 July 2020

New Turret

"November 15th, 1942
#SO4899

To the chief of the BTU, Colonel comrade Afonin
Moscow, Red Square, 2nd NKO house

People's Commissar of Tank Production, comrade I.M. Zaltasmann
Moscow, 11 Sadovo-Sukharevskaya street

Director of factory #183, comrade Yu.Ye. Maksarev

RE: review of T-43 and T-44 tank projects 

In addition to my letter #SO-4698 from November 2nd, 1942, sent to you and copied to the Deputy People's Commissar Zh.Ya. Kotin, the following must be said about the results of review of T-43 and T-44 tank projects.

As I already informed you, the following requirements were key in the development of the T-43 tank:
  1. Maximum possible thickening of the armour while maintaining the same weight as the T-34.
  2. Maximum possible simplification of all components and assemblies to reduce production complexity.
  3. Maximum use of T-34 components that are already mastered by factories.
These requirements were set in order to increase the rate of production at our tank factories while preserving equal tactical-technical characteristics to the T-34 tank.

This solution allowed a faster transition to a new type of tank and did not require retraining of crewmen, and did not complicate the issue of spare parts.

All other solutions, including those that satisfy the tactical-technical characteristics you provided, do not provide a simpler to produce and more reliable vehicle.

A prototype could be built in accordance to your requirements, and this vehicle will be no worse than the prototype that we build now, but it is simply not possible to build such a vehicle now, while we are at war, no one will allow it.

Moving to a new vehicle will always result in a temporary reduction in production rate while the factory changes over to the new design. The more new elements there are in the new design, the more time and effort it will take to master production.

This risky experiment cannot be performed at the moment.

Your requirements do not take this into account. For example:

1. The drive sprocket must be a pin gear.

This requirement does not take into account that there is no track for a pin gear. Development and trials will take a long time, not counting the effort it takes to put into production. In my opinion, there is no benefit in a pin gear.

2. The turret ring must be 1600 mm in diameter to freely fit 3 people.

This requirement changes the vehicle at its core. In addition to losing any possibility of compatibility with T-34 turrets, a large amount of effort will be required to convert the production line and alter the tooling to produce new turret rings, as well as alterations to the tooling to produce turrets.

An increase in the turret ring diameter will require an increase in the diameter of the tank overall, and will therefore increase the weight of the tank by approximately two tons, which will reduce the mobility of the tank and the reliability of its components.

In my opinion, that is unacceptable at this time.

3. The commander must have prismatic observation devices in a rotating observation cupola.

You are suggesting some kind of new observation cupola with new observation devices, which will once again require time to develop and master, meanwhile the commander's cupola that was already tested on the T-34 could be used for this purpose, which we already did.

I don't dare to draw your attention from other issues, but the tactical technical characteristics are divergent from what we are trying to achieve with the new design. I ask you to clarify the situation, as, I repeat, you made no complaints from June until October, the moment when comrade Stalin permitted this work to continue.

I would consider it more appropriate to not introduce any changes into the tank prototype that we built and to produce it in the state that it reached in October. I accept your requirements for a new prototype and will have the designers work on them.

I ask you to reply with your decision on the issue at hand.

Chief designer at factory #183, Morozon
November 15th, 1942"

CAMD RF F.38 Op.11355 D.743 L.43

1 comment:

  1. To explain the reference to a pre-existing observation cupola, you link to a page on the "MK-4" Gundlach periscope - but on that page, you say this was not prototyped until May '43, several months after the date of this document.

    Had there been an earlier prototype? Or is this a reference to the original observation periscope that was installed in a non-opening cupola in the middle of the hatch, and deleted in early production?

    There seems to be a lot of confusion about this device in secondary sources (at least in sources accessible to English-language amateurs like myself) - the device is generally identified as a "PTK" and described as a variant of the PT-series periscopic gunsight located in the "pepperpot" on the front left of the turret, but diagrams depict a completely different (and much more straightforward) observation device.

    I suspect there has been some confusion between this early "cupola" and a simplified observation-only variant of the PT "pepperpot", noted here as an alternative installation in the front-left position:

    https://www.tankarchives.ca/2017/03/tank-costs-1943.html

    Is this covered in your book? Or are you willing to offer quick clarification here?

    Also, is the 26° view from the PT periscope the angle at x2.5 magnification? Could the device be zoomed out to obtain a wider x1 view?

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