Monday 17 August 2015

T-34 Spaced Armour

"To the Chair of the State Committee of Defense, comrade Stalin

We report on the results of testing German and domestic HEAT and subcaliber shells against a T-34 hull and spaced armour plates and on improving protection against these shells. This work was performed by GABTU, TsNII-48, and factory #112.

As a result of the trials, it was determined that:
  1. T-34 armour is insufficient against HEAT and especially subcaliber shells. The most vulnerable parts of the tank are the sides, the turret, the overtrack hull, and to a degree the rear.
    German 50 mm subcaliber shells with a muzzle velocity of 1200 m/s penetrate the side of the tank from 1260 meters, the turret from 690 meters, the overtrack hull from 530 meters, and the rear from 360 meters.
    The front is impenetrable, aside from the connecting joint, which can be penetrated from 600 meters.
    The German 75 mm HEAT shell can only penetrate the lower hull side, destroying the bottom of the overtrack hull and the suspension.
    Additionally, the HEAT shell destroys holders and anything that sticks out when it hits the rear, and can penetrate the roof of the hull if it hits low enough on the turret.
  2. As a result of trials, it was determined that the best measure against HEAT and subcaliber shells is spaced armour, located 100-600 mm from the main armour. In order to protect against HEAT shells, an iron plate only 4-5 mm thick is enough. To protect against subcaliber ammunition, 16 mm of armour is necessary.
    As a result, when the sides of the tank have spaced armour 16 mm thick, the T-34 will be almost completely protected from 50 mm subcaliber and 75 mm HEAT shells from a range of 50-360 meters.
    We ask that you let us produce T-34 tanks at factory #112 to test in battle, in two variants:
    1. First variant: 15-16 mm screens for the upper and lower sides and turret. The mass of the tank will increase by 2622 kg, which will make the tank 1152 kg heavier than a mass produced factory #183 tank.
    2. Second variant: upper and lower sides with spaced armour 10-15-16 mm thick. The mass will increase by 1833 kg,  which will make the tank 363 kg heavier than a mass produced factory #183 tank.
Deputy Chief of GABTU, Major-General of the Tank Forces, Korobkov
People's Commissar of Tank Production of the USSR, Zaltsmann



State Committee of Defense, decree #2594ss

Moscow, Kremlin
December 7th, 1942

The State Committee of Defence decrees that:

In order to improve protection of tanks from HEAT and subcaliber shells, the following must be done:

1. The People's Commissar of Tank Production (comrade Zaltsmann) and factory #112 director (comrade Rubinchik) must produce 46 T-34 tanks with spaced armour by March 1st, 1943, as a part of the quota for the first quarter of 1943. The variants are as follows.
VariantAmountTank partSpaced armour thickness in mmSpace between armour plates in mm
123Lower side
Upper side
Turret
15-16
15-16
15-16
630
120-260
70-150
223Lower side
Upper side
15-16
15-16
630
120-26

2. GABTU (comrade Fedorenko) must test these tanks in combat during February and March and present GOKO with conclusions.
3. The People's Commissar of Tank Production (comrade Zaltsmann) and factory #38 director (comrade Yakovlev) must develop spaced armour for the T-70 by February 15th, 1943, test two prototypes together with GABTU. Present GOKO with conclusions by March 25th, 1943.

I. Stalin."


However, the T-70 wasn't lucky enough to get extra armour. The entire section is crossed out and marked "exclude completely".

8 comments:

  1. I take it these are the short-barreled 50 mm and 75 mm guns, originally on the earlier PzIIIs and PzIVs? December 1942 is somewhat late to be making change specifically to redress those problems, given that both those tank/gun combinations were well on their way to being withdrawn from service.

    And were these measures implemented?--from seeing those pictures of T-34s in Berlin sporting Panzerfaust screens.

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    Replies
    1. Long barrelled 50 mm and short barrelled 75 mm, yes. These tanks were built in very limited numbers, likely for the reason that you mentioned.

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    2. What happened with battle trials? There was not a mass production, as I know...

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    3. They ran into something more dangerous than 50 mm guns. http://tankarchives.blogspot.ca/2013/10/up-armoured-t-34s.html

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    4. So..that's why the early model of T-34s as you put URLs shows it..they meet...a very dangerous gun.

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  2. I am confused. The 50mm gun can penetrate ~75mm-80mm with AP but with APCR it can penetrate ~110mm (?) but cannot penetrate 90mm effective? Why is this? Is it because it lacks KE?

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    Replies
    1. Spaced armour drastically reduces the effectiveness of APCR since it strips off the sabot component and can shatter the core prematurely.

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    2. So sorry. Missed the part about spaced armour

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