Sunday, 9 March 2014

Soviet Stabilizers



Present:
NTK chair, comrade Ozerov
5th Section chair, comrade Keller
Engineer, comrade Norenberg
From NTK AU, comrade Saks
Meeting chair: Ozerov
Secretary: Keller

On the topic of: engineer Norenberg's proposal of a servo-gyroscopic device for tank gun stabilization

Conclusions:
  1. First, build an (experimental) stabilizer for the 37 mm gun, as well as stabilize the turret horizontally with a servo-gyroscopic device.
    In the vertical plane, stabilize the gun relative to the turret, without correcting oscillations parallel to the firing axis, such as tilting. The device must allow the gunner to move the gun with his own force, without lag from the stabilization equipment. 
  2. Engineer Norenberg must provide overall draft blueprints by March 1st, 1930.
  3. Ask NTK AU and NTK UMM to develop preliminary Technical Specifications.
  4. 5th Section of the NTK UMM should familiarize engineer Norenberg with the nature of tank oscillations.
  5. Propose to engineer Norenberg to provide an overall diagram and dimensional blueprints of the gun stabilizer devices.
Signatures."

Look at that, bi-planar stabilization, in 1930! Sadly, I have not seen anything on more stabilizers for the MS-1, but this is far from the last time gun stabilizers appear in Soviet documents.

The idea of a turret stabilizer appears once more in 1939, for the BT-7, in a list of experimental developments at factory #185. In that same year, a stabilizer is proposed for the T-28's gun. Stabilizers were also proposed for the IS tank (and were actually built for the IS-5, although I am unsure about others). 

More stabilizers are mentioned in CAMD RF 38-11369-1.

"3. Work on stabilizing tank weapons.

In tank combat, aside from shooting from a stationary position, a tank must fire on the move. The conditions of firing on the move had to be as close as possible to the conditions of firing while stationary, from the point of view of accuracy, rate of fire, and convenience of loading. 

In order to solve this task, SKB NKSP, according to GOKO decree #3826 from July 28th, 1943, began designing and manufacturing experimental gun stabilizers for medium tanks in July of 1943, according to technical-tactical requirements from USA GBTU.

The design of domestic stabilizers took into account the experience with American gun stabilizers. However, domestic stabilizers work on a completely different principle, as they are based on the idea of forceful stabilization. This provides our stabilizers with higher precision than American indicator stabilizers.

The following gun systems were equipped with stabilizers: 76 mm American gun on the M4-A4 tank, 76 mm F-34 gun on the T-34, and the 85 mm S-53 gun on the T-34-85. The  latter designs corrected the deficiencies of the former.

Currently, according to GOKO degre #6896s from November 7th, 1944, a trial run of 5 T-34 tanks with STP-S-53 stabilizers are being prepared for trials."

While I haven't read anything about the Soviet Sherman stabilizer, the stabilizers for the T-34 (STP-34) and T-34-85 (STP-S-53) are more widely known. I do not have a photograph or a description of the STP-34, but I do have them for the STP-S-53. Since they were designed and built at the same time, it is likely they operated on the same principles.

STP-S-53 stabilizer in a T-34-85 tank
1. Hydraulic cylinder 2. Oil tank 3. Hydraulic pump 4. Electric motor 5. Damping gyroscope 6. Force gyroscope 7. Vertical aiming flywheel 8. Stabilizer switch 9. Hydraulics switch 10. GKZ-T modulator

Solyankin et al describe this device in their book "Domestic Armoured Vehicles, 20th century, volume 2". Skipping over the technical minutiae, let's go straight to the conclusions: "Trials showed good results. Conditions of firing on the move were close to conditions of firing from a stationary position. The stabilizer eased the task of vertical aiming, and the automatic firing mechanism reduced the shell's lag time, further decreasing vertical dispersion."

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