Temporary Reinforcement
Modernization often starts immediately after a tank is accepted for service and put into production. The T-34 was no exception in this regard. A number of changes to simplify production and improve the tank’s characteristics were made in the first year. The T-34 changed even more radically in 1941. For instance, the L-11 gun was replaced with the F-34 gun in March of 1941. There were also plans to improve the armour, but they were only partially realized. Let us discuss the applique armour used on T-34 tanks from 1941 to 1943.
Unavoidable reinforcement
A new stage in Soviet applique armour design began in the spring of 1941. In addition to work on applique armour for T-26 and T-28 tanks, designers received the task to develop applique armour for the KV-1 and KV-2 tanks. This was triggered by intelligence on new types of German tanks that was acquired in March of 1941. According to this information, German “Type V” and “Type VI” heavy tanks were equipped with 75 mm guns capable of defeating Soviet heavy tanks.
Decree #548-232ss was signed by the Council of People’s Commissars and the Central Committee of the Communist Partyon March 15th, 1941. It required to produce prototypes of KV-1 and KV-2 tanks with applique armour by May 1st and put them into mass production by June 1st. This work was only a temporary solution. In the summer, KV tanks with thicker main armour would enter production. This plan was put into action, but only for the KV-1, as the KV-2 was already overloaded. Even though German heavy tanks did not show up on the Eastern Front in 1941, the idea of thickening the armour was correct.
Blueprints of applique armour for the T-34 turret. The blueprints were approved on June 13th, 1941.
Another one of the Red Army’s new tanks received applique armour, the T-34. This happened later and for different reasons, and was not because of the intelligence informtaion.
Two hulls and two turrets were shot up at the Mariupol factory between April 1st and April 12th, 1941. The guns used were the 37 mm Polish Armata przeciwpancerna 37 mm wz. 36 Bofors, 37 mm model 1930 anti-tank gun, two 45 mm model 1937 anti-tank guns, and the 76 mm divisional model 1902/30 gun. It turned out that parts of the hull can be penetrated by 45 mm sharp tipped armour piercing shells from up to 600 meters. The sides were most vulnerable. The front of the hull was the most resistant and even withstoof 76 mm hits, but even it had weak zones.
45 mm thick armour no longer seemed like enough.
Applique armour for the hull. This design was rejected because bolts could be destroyed in one hit from a shell.
This was not news for factory #183’s design bureau and the GABTU. Tactical-technical requirements for a “T-34 tank with a T-60 torsion bar suspension” (later T-60 was corrected to T-34-T) were approved on March 5th, 1941. The number 60 stood for 60 mm of front armour. It was already known that 45 mm of armour did not give complete protection from the 45 mm gun.
The story with the reinforcement of the T-34’s armour continued in April of 1941. A proposal was made to increase the thickness of all front armour to 60 mm. The floor armour was thickened from 20 to 30 mm. This tank was called A-43.
The issue of reinforcing armour on ordinary T-34s was also raised. Decree #1216-502ss of the SNK and Central Committee “On production of T-34 tanks in 1941” was issued on May 7th, 1941. It raised the issue of producing the A-43 and T-44 (A-44) tanks. The 10th paragraph of the decree is the most interesting in this context.
"It is ordered that:
- The People’s Commissar of Medium Manufacturing (comrade Malyshev) and director of factory #183 (comrade Makrarev) jointly with the People’s Commissariat of Defense (GABTU) are to produce and test two prototypes of T-34 tanks with additional armour of the turret and front plate, 13-15 mm thick, in June. Install applique armour of 500 T-34 tanks already in service by sending out brigades with instruments and materials.
- The People’s Commissar of Shipbuilding (comrade Nosenko) and director of Mariupol factory (comrade Garmashev) must produce armour plate for applique armour of two T-34 tanks within two weeks of receiving blueprints from factory #183.
- The People’s Commissariat of Defense (GABTU, comrade Fedorenko) must organize bases for installing applique armour on T-34 tanks, equipping them for welding and mechanical work, and supplying auxiliary workers.
STZ and factory #183 are to begin production of tanks with applique armour starting in August of 1941.
The Mariuopol factory is to begin supplying factory #183 with applique armour parts in July of 1941.
Factory #264 is to begin supplying STZ with applique armour parts in July of 1941."
This applique armour did not exist even as a draft at the time this decree was signed. Factory #183 had yet to design them. The armour department of NII-48 was also involved in the work. Some publications claim that the applique armour was developed in May of 1941, but that is not so. According to the summary report on experimental work, the blueprints were still being developed in May. Instead of 15 mm thick plates, the factory used up leftovers from BT-7 production, which were 13 mm thick. By the start of June, it was not yet decided if the armour would be attached with welding or bolts. The factory preferred bolts with a space of 25 mm between the main armour and applique armour. The first trials were performed in May. It turned out that the ballistic limit (the impact velocity of the shell needed to penetrate the armour) increased by 40-55 m/s.
T-34 with serial number 811-28, one of the two tanks that received applique armour.
Documentation on the applique armour was ready by mid-June 1941. As before, the applique armour was bolted to carriers, which were welded onto the main armour. The front of the hull was protected by four plates on the top and two on the bottom. This layout was the simplest to produce and allowed to quickly replace the armour in case it was damaged. The connecting beam did not have additional armour, but there was a variant of the armour developed for tanks without a beam. The turret was reliably protected. Extra armour was installed along its perimeter and protected the turret ring as well as the main armour. The total mass of the applique armour was 1050 kg according to calculations.
This photograph was taken in July of 1941 at factory #183.
As required, two tanks were equipped with applique armour. These were tanks with serial number 0618-7 (1940 production with L-11 gun and no connecting beam) and 811-28 (1941 production with an F-34 gun and connecting beam). This was done in July, not June. 120-140 man-hours were required to convert one tank, which was within norm for this kind of work.
To figure out how this change affected the tank’s characteristics, a third tank (#311-25-3) was loaded up to 28.5 tons and tested in spring-summer of 1941. No exceptional issues were discovered after a 1697 km march. However, the general drawback of tanks with applique armour showed itself. The front of the tank dipped significantly when driving on bumpy roads.
Leftover 13 mm thick armour from BT-7 tanks was put to use.
The widespread opinion that the applique armour project was cancelled because of the start of the war is incorrect. Yes, hull production facilities were overloaded, but there were also many issues with the applique armour design. The attachment by bolts was unreliable, as the first hit from a shell would break them off. The design with mudflaps was also complicated.
The applique armour was to be changed. The armour would be installed without spacing, and would be attached by welding. The sloped sides around the fighting compartment would also receive additional armour. NII-48 also had its complaints. They noticed that the armour does not cover the most vulnerable parts of the front of the tank: the driver’s hatch and hull machinegun. However, these components were not covered on any subsequent applique armour design either.
In any case, the design developed by factory #183 was rejected. It would not have gone into production in any case. Both tanks with the applique armour were sent to the front lines. The tank with an F-34 gun even popped up in a front line photo.
Second coming
A lull took place after factory #183’s design was rejected in July of 1941. Unlike the KV-1, the T-34 never received thicker main armour. The tank continued to be produced with 45 mm thick plates. The issue of applique armour arose once more in the fall of 1941. This was triggered by the analysis of use of the T-34 in combat and captured German memos on combat with Soviet tanks.
This information coincided with the findings of spring 1941. The front of the tank was the toughest part, but the lower sides could be penetrated by light anti-tank guns from 400 meters and closer. The situation with the 50 mm Pak 38 was even worse. The T-34’s side could be penetrated from 700 meters. The 105 mm leFH 18 howitzer could also penetrate the side from that distance.
A proposal was made in October of 1941 to install applique armour along the sides. The sloped part of the side would be covered with a 15 mm plate, the suspension covered with 25 mm thick spaced armour. The turret ring would be protected from the sides and front to prevent jamming. To compensate for the increase in mass, smaller road wheels with internal shock absorption would be used.
In practice, work on up-armouring T-34 tanks went in a different direction. The production of the A-43 was a pipe dream by the fall of 1941, so a decision was made to improve the existing design. Even though results of trials showed that it was necessary to increase the sides of the hull, the front armour of the tank still came under the most frequent attack. It was decided to reinforce that part.
A technical meeting was held at factory #112 in mid-November 1941 to discuss this question. This topic was mentioned several times in the NKTP. On December 25th, 1941, Stalin signed GKO decree #1062ss “On T-34 and T-60 tanks”. According to this decree, all T-34 tanks were to be produced with applique armour increasing the total thickness of the front armour to 60 mm from January 15th and 60 mm thick main armour after February 15th.
T-34 tanks with applique armour produced by factory #112. Leningrad Front, summer of 1942.
By this point, three factories were producing the T-34: Stalingrad Tractor Factory (STZ), factory #112 (Gorkiy), and factory #183 (Nizhniy Tagil). Factory #183 remained the chief factory, but by the start of 1942 all three factories were producing noticeably different tanks. Factory #183 began producing a hexagonal turret with some features from the A-43 turret (gun mount, separate round hatches, etc) due to technical difficulties with the old design. The hulls also had their differences. STZ and factory #112 tanks also differed. With time, these differences only increased.
Even though requirements only stipulated increased armour in the front, this layout has applique armour even in the back of the turret.
Factory #183 had their own approach to decree #1062ss. According to a letter sent on January 3rd, only the front of the hull would receive applique armour. The protection of the turret was improved by increasing the thickness of the main armour to 60 mm. Considering that the turret was cast, and that 52 mm of cast armour was considered equivalent to 45 mm of rolled armour, this was not enough protection. In practice, turrets were still cast with 52 mm armour.
Factory #112 developed a scheme where the front of the hull and the front (and partially sides) of the turret were covered with additional 15 mm thick plates. Like the factory #183 design, they were welded on. This design used small sheets of armour.
In Stalingrad, the development of applique armour was taken up by the supplies of hulls and turrets: factory #264. This factory also developed a layout with improved armour in the front of the hull, the front of the turret, and partially the sides of the turret. Recall that factory #112 mainly used cast turrets, and factory #264 mainly welded ones.
