Tank Review

"To the Chief of Staff of the 31st Vistula Order of the Red Banner Order of Suvorov Order of Kutuzov Tank Corps

I present to you the report on application of tank armament in the Patriotic War. The materials were collected in conversation with the 242nd Order of the Red Banner Order of Suvorov Tank Brigade.

Attachment: the aforementioned on three pages.

Chief of Staff of the 242nd Tank Brigade, Captain Hohlenkov

June 22nd, 1945"

"Report on the use of tank weapons in the Patriotic War

1. Notes on the design drawbacks of guns, machine guns, and ammunition

Big Guns for the T-34

There is a large category of fans of alternative history who like to install large guns into small tanks. These people don't exist only on the internet, but also among popular authors of quasi-historical publications. They sometimes even provide some kind of schematics and make grandiose projections. While modern plans have little to do with reality, tank designers many years ago worked towards very similar goals. Every army wanted to put a larger gun into its tanks. This typically happened as a result of increased requirements for tank guns. This process started very early in the USSR. The MS-1, the first Soviet mass produced tank, was built with a 37 mm Hotchkiss gun. This was far from the only weapon proposed for it. The same gun mount could have been a home for a "high power 37 mm gun" or "37 mm Rheinmetall gun". There were many cases where the proposed gun would simply not have fit into the fighting compartment. For instance, this was the case with the AT-1. The 76 mm PS-3 gun failed to enter production and took down the SPG with it. Other 76 mm guns (for instance the L-10) wouldn't fit.

The 85 mm AA gun was seen as a potential anti-tank weapon and tank gun back in the summer of 1940.

King Tiger Field Penetration Trials

"Report on the results of testing the T-6-B King Tiger superheavy tank in order to determine its weak points held on September 2nd, 1944, near Staszów by a commission composed of the following: [names]

The results of the trials are summarized in the following table:

Component of the tank	Gun caliber	Type of ammunition	Range	Angle	Result
Hull front	152	HEAT*	250 m	90	First hit: 350 mm wide breach in the machine gun ball.
				46	Second hit: 70 mm deep dent 230 mm in diameter.
	85	AP	200 m	46	60 mm deep dent 170 mm in diameter.
Turret front	57	Subcaliber	200 m	75	165 mm deep dent 70 mm in diameter.
Turret side	152	HEAT*	1200 m	70	Penetration, 200 mm breach.
			250	86	Penetration of both sides, entrance breach is 190 mm in diameter, exit breach is 840 mm in diameter.
	85	AP	200	86	Penetration 170 mm in diameter.
Superstructure side	152	HEAT*	465	85	Penetration of both sides, entrance breach is 170 mm in diameter, exit breach is 750 mm in diameter.
	85	AP	400	85	Penetration 150 mm in diameter.
	76	Subcaliber	300	88	Penetration 40 mm in diameter.
		AP			Dent 75 mm deep 84 mm in diameter.
	57	Subcaliber	200	88	Penetration 70 mm in diameter.
		AP	200	88	Penetration 60 mm in diameter.
	45	Subcaliber	150	80	Penetration 30 mm in diameter.

Comparing Shells

 "Report of the GBTU Self Propelled Artillery Directorate on results of comparative penetration trials of American, German, and domestic AP shells
May 13th, 1945

Firing according to the attached velocities was done at the Main Artillery Proving Grounds of the GAU at NKB proving grounds at Sofrino

Results of firing the shells at armour plates at prescribed velocities (see table)

#1: 76 mm AP shells against 50 and 75 mm thick plates.

The experimental shell from 60Kh30 steel shows undoubtedly superior results compared to the stock shell or the American shell.

85 mm Gun Instructions

"Instructions from the 4th Department of the Combat Training Directorate of the Armoured and Mechanized Forces of the Red Army on the specifics of using the 85 mm tank gun

February 23rd, 1944

1. The T-34 tank uses two types of 85 mm gun: D5-T-85 and S-53.
   In combat the guns are serviced by two crewmen: the gunner and the loader.
2. The differences in characteristics of the weapons are negligible. Both are meant to combat enemy armoured vehicles, suppress artillery batteries and anti-tank guns, as well as enemy personnel, at ranges of 1500-2000 meters.

Big Gun, Small Turret

 "State Committee of Defense Decree #4873ss
January 1st, 1944

On installing 85 mm guns on T-34 tanks instead of the 76 mm F-34 gun

To improve the artillery armament of the T-34 tank, the State Committee of Defense orders to:

1. Accept the 85 mm tank gun designed by the Central Artillery Design Bureau of the People's Commissar of Armament (comrade Grabin) into service with the Red Army under the name "85 mm tank gun model 1944 (S-53)".
2. Starting with January of 1944, equip T-34 tanks with 85 mm model 1944 (S-53) tank guns installed in turrets on the stock turret ring instead of the 76 mm F-34 gun.

Big Gun, Small Turret

 

"The 85 mm S-53 tank gun is installed in the regular T-34 turret. The stock turret is 130-150 mm narrower than the one housing the LB-1 gun and the turret bustle is smaller, fitting just 5 rounds instead of 12.

Muzzle Brake Requirements

"USSR NKO

GBTU KA

Tank Usage Directorate

July 4th, 1944

#542526

To Assistant Commanders in charge of Armoured and Mechanized Warfare of Fronts

Copy for the Assistant Commanders in charge of Armoured and Mechanized Warfare of the 1st Baltic Front

A report by the Usage Department of the Armoured and Mechanized Warfare of the 2nd Ukrainian Front in February and a report of the NKTP inspector's group at the 1st Belorussian Front in May indicated vases where the gearbox of the T-34 tank with an 85 mm gun broke when the gun was fired on the move.

T-34s vs Tiger

"

Report

On military trials of T-34 and T-34-85 tanks against the T-6 "Tiger" tank

2nd Tank Battalion, 63rd Guards Tank Brigade

June 16th, 1944

1. The 2nd Tank Battalion fired the guns. The battalion commander, Guards Captain Chirkov, was directed by the brigade commander, Guards Colonel Fomichev, in the presence of the deputy commander of the 10th Guards Tank Corps, Guards Colonel Belov, Chief of Staff of the 18th Army, and the senior officers of the 18th Army.

2. Firing was done against a German Tiger tank from 400, 600, 800, and 1300 meters.

T-34-85 Review

"Report on the use of the T-34 in combat during the Patriotic War in the 37th Guards Tank Regiment

1. The S-53 gun installed on the T-34 tank has a number of design drawbacks, such as:
1. When firing, the electrical firing mechanism burns out, and until the end of the battle one is forced to use the manual firing mechanism.
2. The recoil break grease nipples break after 1300-1500 shots, which then need replacing. The factory quota promises 2000 shots before replacement.
3. The DT machinegun, both in the coaxial mount and in the hull, has a very small brass catcher, and there are frequent stoppages because of it. There is enough room to make it bigger both for the coaxial and the hull machinegun.

Light SPGs with Big Guns

The SU-76M SPG, armed with the ZIS-3 76 mm gun, was the second most numerous vehicle in the Red Army. This gun was one of Grabin's best, and had very respectable characteristics. Nevertheless, the idea of installing a more powerful gun was persistent, and some variants, such as the SU-85B, came close to entering production. However, the Red Army never received its domestic Marder.

T-44 Prototype #2 Rate of Fire Trials

"Results of firing

Firing from standstill at an angle of 0 degrees. 

Target	Range	# shots	# direct hits	# of hits within 30 meters	Time spent	Rate of fire	Notes
Panther. Aiming was done using manual traverse.	900	10	8	2	1 min 5 sec	9.2 RPM	All rounds in turret rack
Panther and PzIII in a 30 deg arc. Aiming was done using manual traverse.	800	5	5	-	1 min 25 sec	7 RPM	5 rounds in the turret rack, 5 rounds to the right of the driver
	1000	5	5	-
Panther tank, PzIII tank, 3x3 meter target in a 40 deg arc. Aiming was done using manual traverse.	800	3	3	-	1 min 40 sec	5.4 RPM	All rounds stored to the right of the driver
	1000	3	3	-
	1500	4	4	1
Panther tank, PzIII tank, 3x3 meter target in a 40 deg arc. Aiming was done with electric traverse.	800	5	5	-	2 min 40 sec	3.7 RPM
	1500	5	1	2

ZIS-S-53 Gunnery Trials

"VII. Trials of armament

Firing the 85 mm mod. 1944 ZIS-S-53 gun

1. Determining accuracy and precision of fire

Accuracy and precision trials were performed using steel HE grenades. Aiming was done with the stock TSh-15 sight.

Ambient temperature: +32 degrees C.

Visibility: good

Range: 1000 meters

Angle of the tank: 0 degrees

Time for firing: unlimited

Fire correction was performed after every shot

Results:

Conditions	Distance to target	Shots fired	Shots hit	Dispersion radius, cm
				100	50
Firing from standstill at a vertical target initially.	1000 m	10	10	95	45
After mobility trials and 230 shots	1000 m	10	10	54	36

An Opponent for the Tiger

The capture of two Tiger tanks by the Red Army on January 18th, 1943, had a significant impact on Soviet tank building. Trials of one of the tanks revealed an unfortunate fact: the F-34 76 mm gun, the main weapon of Soviet tanks, could not penetrate the side. The reaction to this result was swift. Designers were tasked with developing a more powerful tank gun immediately. It was to be installed in the KV-1S heavy tank.

New Gun for the T-34

"On arming the T-34 with an 85 mm gun instead of the 76 mm F-34 gun

In order to improve the artillery armament of the T-34 tank, the State Committee of Defense decrees that:

1. The 85 mm tank gun designed by TsAKB (comrade Grabin) is accepted into service and named "85 mm tank gun model 1944 (S-53)".
2. T-34 tanks, starting with January of 1944, will be armed with the 85 mm tank gun model 1944 (S-53), installed with the stock turret ring, instead of the 76 mm F-34 gun.

Valentine Improvement

"To the Chief Engineer of TsAKB and TsAKB Chief, Lieutenant-General of the Technical Forces, comrade Grabin

April 18th, 1944

Valentine tanks armed with a 40 mm gun continue arriving from England in the USSR.

The penetration of this gun is low and, as experience shows, it cannot fight against modern German tanks in battle. In addition, the ammunition used with the 40 mm gun does not include a high explosive shell, making these tanks ineffective against infantry.

I ask you to determine the possibility of designing and producing an experimental Valentine tank with an 85 mm S-53 gun.

It is necessary to include a 7.62 mm machinegun with 360 degree range to combat enemy personnel.

GBTU USA Chief, Major-General of the Engineering Tank Service, Alymov."

CAMD RF 38-11369-284

Under Pressure, Part 2

In Part 1, we saw what happens to a tank crew when it's hit with a HEAT shell, whether that shell penetrates or not. However, getting hit with a kinetic penetrator has consequences too! Let's take a look.

"To compare, a table of measurements inside armoured compartments on impact from armour piercing and high explosive 76, 85, 100, and 122 mm shells with sensors positioned 200-1000 mm from armour, under the condition that the armour integrity was not compromised."

Tiger Manual

"

Translated from German.

Supreme Command of the Land Forces

4300/43 Secret

October 30th, 1943

Combat training instruction #14
Usage of PzKpfw VI Tiger tanks

Rules were composed based on summarized experience of units that used the PzKpfw VI Tiger tank in recent battles.

1. Vulnerability of the tank

The frequently displayed opinion about the invulnerability of the PzKpfw VI is a mistake, and often leads to improper use of the Tiger tank, which causes excessive losses.

T-34-85 Stabilizer

"State Committee of Defense Decree #5595s
April 11th, 1944
Moscow, Kremlin

Introduce a partial change to GOKO directive #3826s issued on July 27th, 1943:

1. The NKSP (comrade Nosenko) and the NKSB design bureau (comrade Rozanov) must produce a stabilizer for the S-53 85 mm gun in the T-34-85 tank with a widened turret ring by May 1st, 1944, instead of the D-5 gun in the IS tank.
2. Commander of the Armoured Forces comrade Fedorenko must provide one T-34-85 tank to the NKSP design bureau for the installation of an experimental stabilizer by April 15th.
3. NKV (comrade Ustinov) and NKTP (comrade Malyshev) must provide one set of blueprints of the 85 mm S-53 gun and T-34-85 tank with a widened turret ring to the NKSP design bureau by April 15th.

Deputy Chair of the State Committee of Defense

V. Molotov."

RGASPI 644-2-309

D-44 Ballistic Tables

The D-44 85 mm divisional gun had the same ballistics as the S-53. Despite being designed in 1944, it did not enter production until after the war, but these tables can grant us some insight into how well the T-34-85 could shoot. 

This table describes the blunt tip APBC round BR-365. The muzzle velocity of this round is 800 m/s, and its flat shot range for a 2 meter tall target is 950 meters, 1090 meters for a 2.7 m tall target and 1150 meters for a 3 m tall target. The columns of the table are as follows: distance, three settings for the sight, trajectory height, two columns for various corrections, one column with the change in impact height for one division of the sight, the angle of the gun, the angle of impact, impact velocity, time of flight, and then finally, the two columns we care about, vertical and horizontal mean dispersion. As you can see, the dispersion is only 0.2 x 0.3 meters, which is very good, but not quite as good as on the pre-war U-10 design.

Next we have the BR-367 APCBC shell. Its ballistic properties are almost identical to the BR-365, but it flies a little faster (805 m/s) and is a little more precise (dispersion of 0.2 m by 0.2 m at 1000 meters).

Here is a table for the sharp-tipped BR-365K AP round. Much like the APBC round, it has a muzzle velocity of 800 m/s, but a greater dispersion of 0.3 by 0.4 meters at 1000 meters.

Next is the BR-367P (APCR) and BR-367PZh (APCR with a metallo-ceramic driving band). These shells fly faster than the AP shell, at 1020 m/s, and thus have higher flat shot ranges: 1140 m, 1290 m, and 1350 m. The table columns are a little different, as the sight correction columns are missing. The rest of the columns are the same. These rounds are a little more accurate than the AP at 1000 meters, deviating 0.2 meters in both the horizontal and vertical on average.

This is another APCR shell, BR-365P. With a muzzle velocity of 1050 m/s, it flies a little faster than the BR-367P, but pays for that with reduced precision: a deviation of 0.4 meters by 0.5 meters at 1000 meters. It also loses speed faster than the BR-367P.

Last but not least, the table for O-365K and O-367A HE rounds. This table has a lot more settings, since you care about a whole extra dimension when shooting HE. The first column is, as always, range, then three columns for sight settings with an uncapped detonator, followed by two columns of corrections for a detonator cap and a metallo-ceramic driving band. After that is trajectory height as seen above, but the rest of that page is various corrections for wind, temperature, etc. The first column on the second page is the change in distance corresponding to one one-thousandth change of sight settings, the size of a tight bracket in thousandths, the angle of the gun and angle of impact, impact velocity, time of flight, and finally the dispersion. At 1000 meters, the depth-wise dispersion is 14 meters, the height-wise dispersion is 0.2 meters, and the width-wise dispersion is 0.3 meters.