T-34 Protection Trials

"Conclusions

Based on the trials of two T-34 hulls and turrets, the commission finds that:

1. On the impact of cracks and hot tears around welding on shell resistance:
1. When shells impact the area of cracking, the cracks grow negligibly. In many cases cracks do not grow.
2. The presence of cracks or hot tears in 40 or 45 mm thick armour does not decrease robustness, but is still an undesirable defect that is caused by the quality of the armour and welding. Ilyich factory and factory #183 need to develop measures to resolve these defects.
3. The presence of cracks and hot tears up to 20 mm deep around the weld is unacceptable as they lead to brittle damage to armour when hit. In exceptional cases parts can be permitted with singular cracks or with limited hot tears.
2. On the robustness of the armour and tactical data of the T-34 tank:
1. The hulls and turrets under test showed robustness equivalent to average mass produced components.
2. The armour of the T-34 tank can be deemed satisfactory in resisting 37 mm sharp tipped AP shells with a muzzle velocity of 820 m/s and 45 mm blunt tipped AP shells (blueprint 2-04830) with a muzzle velocity of 760 m/s.
   Areas that can be penetrated by these rounds are small and are located within the range of 60-120 degrees and 150-200 meters. This is a distance that the tank can cover with aimed fire. At other angles the T-34 tank is impervious to 37 mm and 45 mm rounds.
3. The armour protection of the T-34 tank is insufficient against 45 mm sharp tipped proof shells (blueprint 2-01991) with a muzzle velocity of 760 m/s. These shells can penetrate the main parts of the tank (side, rear, turret) from a wide angle at a range of 600 meters or closer.
4. The most protected component is the front. Thanks to the angle of the armour and especially the connecting beam, the front is robust, resilient, and can resist any anti-tank artillery up to and including 76 mm (sharp and blunt tipped). However, the observation devices, driver's hatch hinge, and DT machine gun ball weaken the protection of the T-34 from the front.
5. The turret front has less protection than the hull front, especially the gun port. This reduces the tactical qualities of the T-34 tank. If the turret armour is improved, the T-34 will be able to directly suppress anti-tank guns up to 76 mm in caliber by firing from point blank range.
6. The 40 mm thick pannier sides, despite their angle of 40 degrees, turned out to be weaker than the vertical 45 mm thick sides, especially against 45 mm shells (blueprints 2-04830 and 2-01991). Against 76 mm shells (blueprint 2-03545) and 45 mm shells (blueprint 2-0513) the sloped armour is somewhat tougher than vertical. This kind of difference exists at all angles of fire. According to the Ilyich Mariupol factory, the resilient of the sloped hull section can be increased by changing the thermal hardening (water quenching) process. Thickening the sides to 45 mm would radically improve protection.
7. The armour of the T-34 is generally satisfactory, but individual places are weakened and should be revised to keep up the overall powerful protection:
1. Cutouts in the sides for attaching the pannier floor thins and weakens the entire side across an 85-100 mm strip. Trials showed that this zone can be hit in many cases. Cancel the cutouts.
2. The bend in the rear plate (component 29-007) happens in a place where it can be hit at normal. The bend should be replaced with another combination of components or covered with additional armour.
3. The pannier floor is thin and brittle. When the side is hit the pannier floor cracks, if plugs are knocked out of the pannier sides the pannier floor can be penetrated, shells ricocheting from the tracks can penetrate the pannier floor. HE shells that impact 100-200 mm below the pannier floor can break it. The pannier floor needs to be reinforces.
4. The final drive casings are not armoured enough. 37 and 45 mm shells can penetrating the 25 mm thick casings and the tank will stop. Increase the thickness of final drive casings to 40 mm.
5. The roof of the hull needs to be reinforced, as it can be penetrated by shells ricocheting off the curved turret or broken by HE shells blowing up on the turret.
6. The air intake caps are unsatisfactory, as parts of them protrude above the 16 mm thick roof. The openings for exhaust pipes are hard to protect and it is possible to hit the inside of the tank through them. Cutouts in the sides for suspension arms are insufficiently protected by the wheels, suspension springs, and spring well armour. If hit directly, the shell will enter the tank. This feature should be reviewed in subsequent designs.
8. The running gear of the tank is not protected. If an AP shell hits the track it is not torn and the tank can still move a short distance.
   The ball bearings are destroyed if the hub of the wheels or idler is hit, same with the drive sprocket. Considering the fact that it's hard to hit the hubs, as they are located close to the ground and will often be obscured by terrain, as well as the difficulty in protecting the wheels, the commission finds it unnecessary to armour the running gear additionally.
   If a 76 mm HE shell hits the running gear or the side close to the running gear (100-200 mm) the track, drive sprocket, idler, or wheels are destroyed, and the tank stops.
9. Despite the currently established opinion that penetrations less than the caliber of the shell are not very dangerous for the crew, the commission established that:
1. If the penetration is less than the caliber (i.e. most of the shell mass remains in front of the armour) a plug as well as 8-12 splinters enter the tank.
2. These splinters fly at a significant speed and can damage the crew or mechanisms.
   In designing a new type of tank, designers should develop additional armour methods to protect against these splinters.
10. In addition to the aforementioned drawbacks of the armour itself, the trials process uncovered individual design defects regarding the rigidity of some assemblies and attachments of some components."