Wednesday 23 April 2014

T-34-85 (D-5T) Trials

Photo #3: T-34 tank with an 85 mm D-5T-85 gun from the front, 0 degrees elevation
Photo #4: T-34 tank with an 85 mm D-5T-85 gun from the left, maximum gun elevation

"Report on gunnery trials of the T-34 tank with widened turret ring

Trial goals:
  1. Determine the convenience and effectiveness of firing on the move, from short stops at immobile targets, and while stationary at moving and immobile targets.
  2. Determine the reliability and robustness of aiming mechanisms, firing mechanisms, gun components, and all installation components.
  3. Determine the rate of fire of the gun in various conditions.
  4. Determine the ability to observe the battlefield by all crewmen, determine the dead zones around the tank, develop a vision diagram.
  5. Determine the comfort of ammunition placement.
  6. Analyze the comfort of all crew member positions.
Between November 20th and 23rd, 1943, the T-34 tank with a widened turret ring, a turret designed by factory #183 and armed with the D-5T-85 85 mm gun was tested at the Gorohovets ANIOP.

Trials were performed with the participation of a commission led by Colonel Kulchitskiy, following the order by NKTP, NKV, and the chiefs of GAU and GABTU.

Brief characteristics of the project

The 85 mm D-5T-85 gun is mounted in an enlarged turret on a T-34 tank produced at factory #183, with the following differences from the production turret:
  1. The turret is an aerodynamic shape with a one piece front part that mounts the D-5T-85 gun on carriers welded to it.
  2. The trunnions are inserted into holes in the carriers and attached with 8 bolts. This kind of attachment [rest of paragraph is worn off]
  3. The hull in the middle of the fighting compartment is modified to increase the size of the fighting compartment and make the crew's work freer and easier. 
  4. The D-5T-85 gun system is installed without additional weights.
  5. The gun stopper is positioned on the left, in the left carrier.
  6. The commander of the tank sits to the left of the gun, behind the gunner. He has a commander's cupola.
  7. The enlarged turret has, aside from the periscope, telescopic sight, and two observation slits in the side of the turret, two prismatic observation devices (similar to the English type) one of which is positioned above the loader and one is placed on top of the commander's cupola. There are also 5 slits in the sides of the cupola.
  8. Pistol ports are present underneath the observation slits on the sides of the turret.
  9. There are three folding seats in the turret.
  10. There is a new turret traverse mechanism. The mechanism is activated using the same handle as the hand traverse.
  11. Ammunition is placed in the turret bustle (12 rounds), next to the loader (5 rounds), and in six metal crates on the bottom of the fighting compartment, forming an immobile floor.
Record of the commission on testing the D-5 85 mm gun in the experimental T-34 with the enlarged turret ring and turret produced by factory #183.

According to orders from NKTP, NKV, GBTU KA, and GAU KA, the commission was composed of:
  • Chair: Guards-Colonel Kulchitskiy
  • Members:
    • From GAU KA: Engineer-Colonel Panchev
    • From GBTU KA: Engineer-Captain Rozengart, Engineer-Captain Konev
    • NKV: comrade Volosatov, comrade Plyplin
    • NKTP: comrade Yurasov, comrade Hlopenko
    • TsAKB: comrade Muravyev
The commission tested the 85 mm D-5 gun installed in a T-34 with an enlarged turret ring from November 19th to November 23rd, 1943.

  1. The commission is in agreement with the report of the Gorohovets ANIOP on the trials of the D-5 gun in the T-34 tank with an enlarged turret ring.
  2. The commission remarks that the D-5 meets requirements for the armament of a modern medium tank.
  3. The commission remarks that the turret ring, expanded to 1600 mm, allows the use of the 85 mm D-5 gun with a satisfactory rate of fire, significantly increasing the firepower of the T-34 tank.
  4. The commission remarks that aside from replacing the F-34 gun with the D-5 gun, the widened turret ring also allowed for a third crewman (the tank commander), who is provided with a 360 degree observation device, significantly increasing his ability to observe the battlefield and control the fire of the tank.
  5. The commission remarks that the D-5 85 mm gun increases the firepower of the T-34, but due to its thin armour, does not fully solve the issue of improving the T-34's combat qualities compared to the requirements for a modern medium tank.
    The commission deems it necessary to create new medium tanks with powerful armament and thickened armour, rendering them impenetrable to their own guns at a reasonable range.
  6. During the period of designing and ramping up production of these tanks, the commission deems it reasonable to simultaneously produce T-34 tanks with a stock turret ring armed with 76 mm S-54 guns and begin production of T-34 tanks with a widened turret ring and 85 mm D-5 guns.
  7. The commission considers it necessary for the NKTP and NKV to resolve drawbacks in the T-34 tank with widened turret ring noted in the proving grounds report.
  8. The impact of increased weight on the suspension due to the new turret is going to be determined during trials at the NIBT proving grounds."


  1. >The commission remarks that the turret ring, expanded to 1600 mm, allows the use of the 85 mm D-5 gun with a satisfactory rate of fire, significantly increasing the firepower of the T-34 tank.

    Is it possible to find out what (in RPM) is that "satisfactory" rate of fire?


    1. 5 RPM was their goal, I think. There's a document I have regarding testing the ZiS-25 in a KV-1, and they only reached an average of 2 RPM. The document then notes that unless a rate of fire of at least 5 RPM is reached, there's no point of having an 85 mm gun.