The Hybrid Tank that Led to the T-34-85

There are many cases in history where a tank that remained a prototype helped out another one that went into mass production. In part, this happened with turrets which lost their chassis but found a new home on another tank. Sometimes whole new tanks grew out of the turret, like the Pz.Kpfw.IV. These "centaurs" often grew into true workhorses that were built in huge numbers and remained in service for decades.

A T-34 tank with the T-43 turret, fall 1943.

Two such turrets came into being in 1943. One was the result of work on the Medium Tank T23, a prospective vehicle that was supposed to replace the Medium Tank M4. The replacement didn't pan out for a number of reasons but the turret came in handy when developing the Medium Tank M4(76). A similar thing happened in Soviet tank building. Trials of the turret taken from the second T-43 variant and transplanted on top of a T-34 tank led to the creation of the T-34-85.

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.

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.

SU-85 Production

"Order of the People's Commissar of Tank Production of the USSR #477ss

Moscow

August 9th, 1943

On the organization of 85 mm SPGs on the T-34 chassis at the Uralmash factory

To carry out State Committee of Defense order #3892ss issued on August 8th, 1943, I order that:

1. Uralmash factory director comrade Muzrukov must prepare for production of SU-85 SPGs designed at the Uralmash factory on the T-34 tank chassis and armed with the factory #9 D-5 gun.
2. The following quota for SU-85 SPGs at the Uralmash factory is established:
1. August: 100 units. Production begins on August 25th according to the daily table approved by me on August 8th.
2. September: 150 units.

Panther Penetration

"Maximum penetration at which the armour of the German Panther tank is destroyed

Composed according to experimental firing data.

System	Ammunition type	Maximum distance in meters at which penetration was achieved  during experimental firing						Effect
		Front armour			Side armour
		Upper sloped plate (90 mm)	Lower sloped plate (50-65 mm)	Gun mantlet (100 mm cast)	Turret side (45-50 mm)	Upper side (45-50 mm)	Lower side (45 mm)
45 mm gun mod. 1942	APT BR-240	-	-	-	400	300	400	Complete penetration of the turret and hull side armour.
	APIT BZR-240	-	-	-	400	300	400
	APCR BR-240P	-	-	-	400	300	400
57 mm gun mod. 1941	APT BR-271	-	-	-	1200	1200	1200
	APIT BZR-271	-	-	-	1000	1000	1000
	APT BR-271 SP	-	-	-	1200	1200	1200
	APCR BR-271P	-	-	-	1200	1200	1200
76 mm regimental gun mod. 1927	HEAT BP-354A	-	-	-	600	600	600	Complete penetration of the sloped turret armour.
76 mm regimental gun mod. 1943	HEAT BP-344A	-	-	-	600	600	600
76 mm ZIS-3 mod. 1942	APT BR-350	300	300	-	1200	1200	1200	Penetrates the turret and the side of the hull.
	APCR BR-350P	300	300	-	1200	1200	1200
	HEAT BP-350	300	300	-	1200	1200	1200
SU-76	APIT BZR-354	300	300	-	1200	1200	1200
	APCR BR-354P	300	300	-	1200	1200	1200
SU-85	APT BR-365	1000	1000	1000	1500	1500	1500	Complete penetration of various parts of the hull.
	APT BR-365 SP	1000	1000	1000	1500	1500	1500
122 mm gun mod. 1938	HEAT BP-463	800	800	800	1000	1000	1000	Penetrates armour and detonate the ammunition.
KV-122	APT	1200	1200	1200	1500	1500	1500	A shot to the front destroys the tank.
152 mm gun mod. 1937	AP BP-545	800 m and closer						The front armour is penetrated.

Confirmed: Authorized representative of the Operational Department of Artillery of the 1st Belorussian Front, Colonel Levit

Confirmed: Colonel Utin"

IS-1 Variants

Development of 85 mm tank guns in the USSR began on May 5th, 1943. Multiple competing variants were developed. A new tank was being designed in parallel, and when it was finished there were two 85 mm guns available for it: the S-31 and D-5.

King Tiger Penetration Trials

"ACT

Results of investigation of the T-6-B (King Tiger) tank to discover weak spots and penetration, carried out on September 2nd, 1944, near the city of Staszow (Poland) by a commission composed of:

1. Chair: 
1. Commander of Artillery of the 5th Guards Army, Guards Major General of Artillery V.I. Poluekov
2. Members:
1. Commander of the 31st Guards Rifle Corps, Hero of the Soviet Union, Guards Lieutenant General Rodimtsev
2. Commander of the 155th Novorossiysk Army Cannon Artillery Brigade, Colonel M.A. Tarasov
3. Commander of the 10th Tank Destroyer Brigade, Lieutenant Colonel Bazirenko
4. Commander of the 31st Tank Corps, Guards Colonel Pleshanov

The results are composed into the following table:

King Tiger Penetration Trials

"10th Tarnopol Order of Lenin Independent Guards Tank Destroyer Brigade

September 3rd, 1944

#0302

To: Commander of artillery of the 1st Ukrainian Front, Colonel General of Artillery, Barentsov

CC: Commander of artillery of the 13th Army, Commander of artillery of the 5th Guards Army

I report that on September 1st and 2nd, 1944, I performed penetration trials against the "T-B King Tiger" tank using 57 and 76 mm guns, a 57 mm SPG, an 85 mm gun on a SU-85, and a 152 mm gun-howitzer on an ISU.

Results of penetration trials:

Kotin's Bobtail

In early 1943 the Red Army Main Armoured Vehicle Directorate (GBTU) and People's Commissariat of Tank Production (NKTP) agreed that the age of the KV-1S is coming to an end. Instead, the IS-1 (233), a further development of the KV-13, was to be produced in Chelyabinsk. This tank had the same firepower, but was more mobile and better protected. However, the experimental IS-1 was too unrefined and suffered from assembly issues. In addition, trials of the German Tiger tank showed that the Red Army was in need of a tank with an 85 mm gun. This was how the KV-85 was created, the last mass produced tank in the KV family.

Upgunning the T-43

"T-43 tank turret with the D-5 system

Description

During installation of the D-5 system into the T-43 tank turret, an insert is welded into the gun port, as the D-5 system is narrower than the F-34. An armoured shield is installed in the upper front part of the turret.

The seats of the gunner and commander are located in the same place as with the F-34. The turret traverse mechanism remains in the same place. The elevation mechanism is lowered by 40 mm relative to the elevation mechanism used on the F-34.

The trigger of the system is electric. The trigger is installed in the handle of the elevation flywheel. An electric trigger also works the coaxial DT machinegun. There is also a backup hand firing mechanism for the D-5 gun.

The sights and observation devices of the turret are installed in the same way as they are when in the F-34 is installed.

The radio is located in the same place as when the F-34 is installed.

50 rounds of ammunition are carried, 29 of which are carried in the floor, 16 in the turret bustle, and 5 on the right side of the turret.

Big Guns

"To the Chief of the 16th Department of the GAU Artillery Committee, Colonel comrade Zhevanik

I report on the work that I performed during my trip to Sverdlovsk and Chelyabinsk from May 3rd to May 28th, 1943.

1. Kalinin factory #8.

Based on directions by Lieutenant General of Artillery Hohlov, I organized work to design and produce an experimental 85 mm tank gun. To achieve this, I supplied factory #8 with a copy of the tactical-technical requirements and necessary blueprints with the aid of the GAU military representative at factory #9. I negotiated with the factory's director, comrade Fratkin, as well as the chief engineer and chief designer. Based on this meeting, comrade Fratkin gave the order on May 4th to quickly begin work on designing the gun with the aim of completing blueprints by May 10th.

None More Frightening than the Cat

German industry created three armoured vehicles during WWII that had a significant effect on tank building worldwide. The appearance of the Tiger made Allied tanks obsolete. The few Ferdinand SPGs that were built introduced serious changes into the Soviet tank program. The third tank was the Panther, and its influence was comparable to that of the Tiger.

The tank was a quite unpleasant surprise for the Red Army and its allies when it made its debut at Kursk. Despite its deficiencies, the Panther is a good candidate for the best German tank of the war. The Panther was superior to the Tiger in terms of armament and frontal protection, and was made in significantly higher numbers. Many tank designers were looking at the Panther when they were making the next generation of medium and heavy tanks.

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.

New Turret, Old Gun

The 85 mm gun and enlarged turret for the T-34 were developed as separate projects. I already wrote about what happens when you put the 85 mm gun in the standard hex turret, but there was also the option for the opposite: an enlarged turret with the same 76 mm F-34.

T-34 with the F-34 gun (left) and D-5 gun (right)

Intermediate IS

Joseph Stalin signed GKO decree #4043 "On the production of IS tanks" on September 4th, 1943. This was the end to a long process of the creation of a new Soviet heavy tank that could replace the KV-1 in production. While it was being developed, Chelyabinsk had time to master both the KV-1S and KV-85. However, such a long journey was not for nothing: the Red Army received a completely new tank, the combined characteristics of which put it among the best heavy tanks in the world at the time. The age of the IS-1 (IS-85) was not long. Very shortly it gave up its first place to its descendant, the IS-2, which became the best Soviet heavy tank of the Great Patriotic War.