Monday, 14 July 2014

KV-9 Trials

"According to order #012 of the NKO and the order #48s of the People's Commissariat of Tank Production, the commission led by Major-General of the tank forces comrade Ponov tested the KV-9 tank armed with the 122 mm M-30 howitzer from February 2nd to February 11th, 1942.

1. Goal of trials.

A KV-9 tank produced by the Kirov factory on the chassis of the KV-1 tank (see attachment #1) was submitted for trials. The KV-9 is armed with a 122 mm U-11 (M-30) howitzer designed by the Ural heavy machine building factory. The 122 mm tank howitzer is based on the stock divisional M-30 howitzer (see attachment #2). The KV-9 turret differs from the KV-1 turret in the following ways:
  1. Increased gun port
  2. Altered position of optical devices
2. Trials of robustness and precision.

The factory proving grounds tested the robustness of the gun mount using 171 increased power testing shots. Before trials, the mount was disassembled and measured. The recoil was within the limits of 560-580 mm. During firing, samples of gas concentration in the driver's compartment and fighting compartment were gathered. 

Additionally, the tank made 39 shots at targets at ranges of 600 and 1000 meters with shifts of fire at the Kopeisk proving grounds. The results of the shots are shown in the following table."

The following table does not list where the shots hit, but their time, range, and target are recorded. The tank can reload and fire in as little as 12 seconds, although the time is noticeably larger occasionally (when a target is reacquired, for instance). At 1000 meters, the tank shoots at a 5x5 meter target, at 600 meters, at a 1.25x1.25 meter target. 

"Note: during robustness trials, there were cases where the shell did not extract, which is explained by the use of old steel shells that have been re-loaded and the chamber being dirty.

All targets were hit directly. During gunnery trials, the tank drove 40 km over paved roads and 25 km off-road. The results of the trials are as follows:
  1. The gun and mount system successfully passed robustness trials of 171 increased power shots. Measurements taken before and after trials have no difference between them, and are available in attachment 3.
  2. The recoil mechanisms performed normally and passed trials (recoil remained within 560-580 mm). The pressure in the recoil brake was 27 atmospheres before trials, and 26.5 after.
  3. The rate of fire is two rounds per minute.
  4. The precision is good. Fire can be shifted quickly and without delay.
  5. The elevation and turning mechanisms are comfortable to use.
  6. The loader's position is cramped and makes his job difficult, but ensures the rate of fire of two shells per minute.
  7. The ammunition rack is designed satisfactorily, aside from the following points:
    1. The metallic cover should be replaced with a tarp.
    2. Cut out the metal wall in the section covered by the tarp.
    3. Increase the amount of shells in the turret bustle to 6 shells.
    4. Bead form the metal to increase robustness.
  8. The angle of depression is 2 degrees. It is desirable to increase it to 4 degrees.
  9. The oscillating gun mantlet is not equal in thickness to the front of the turret, and some parts remain uncovered.
  10. The frame cover is cast. It is necessary to use a stamped frame cover.
  11. It is only possible to refill the brake fluid when the tank is tilted by 10 degrees or the recoil brake is removed.
  12. The recoil brake pressure can only be checked when the gun is retracted by 300 mm. It is necessary to move the pressure valve.
  13. There is no foot trigger.
  14. Move the elevation indicator to the gunner's control panel.
  15. Put a pear-shaped cushion on the periscope.
  16. At high elevation, the elevation mechanism carrier can hit the gunner's guard plate. Make a slot in the plate.
  17. Move back the sight 40-50 mm for more comfortable use.
  18. Move the fault indicator, as it is covered by the machinegun.
  19. The manual extractor is inconvenient; it slips off the shell rim.
  20. Tighten the mount for the driver's mirror. There were two cases where is was shifted during fire.
  21. The march stopper is reliable and allows to bring the gun into firing condition within 5-6 seconds.
  22. The angles of deviation are not measured due to a lack of stock shots. The gun was fired using T-34 sights.
  23. Move the DT machinegun up so that the disk magazine does not rub on the gun.
  24. In order to find out the concentrations of gas in the tank, probes were taken after 30-40 shots with the engine off and hatches closed. The results are:
    1. Fighting compartment: 0.201 mg/L
    2. Driver's compartment: 0.308 mg/L
      With the engine on, the concentration is acceptable.
Penetration trials

On February 19th, factory #200 performed penetration trials using the U-11 122 mm tank howitzer and A-19 armour piercing shells. 

Trials conditions:
  1. Shell mass: 24.6 kg (not entirely identical to stock)
  2. The shells were fired at a stock cast KV turret (110-115 mm).
  3. The distance between the muzzle and armour was 100 meters. The first load was 2100 grams of 9/7 powder and 0.030 of igniter. Muzzle velocity: 525.4 m/s. The shell penetrated the turret wall completely and remained behind the armour (see photo #1).
  4. Second shot. Propellant charge: 2200 grams of of 9/7 powder and 0.030 of igniter. Muzzle velocity: 540.2 m/s. The shell punched out a plug and ricocheted (photo #2).
  5. Third shot. Propellant charge: 2300 grams of 9/7 powder and 0.030 of igniter. Muzzle velocity: 546.4 m/s. Same results as the second shot (photo #3).
  6. Fourth shot. Propellant charge: 2400 grams of 9/7 powder and 0.030 of igniter. Muzzle velocity: 573 m/s. Same result as the first shot.
Due to a lack of measuring equipment, the pressure in the barrel was not measured. It is necessary to discover the optimal amount of propellant at the Nizhniy Tagil proving grounds.

Conclusions:
  1. The KV-9 tank passed trials and can be adopted into service with the Red Army.
  2. When producing the KV-9, all aforementioned drawbacks must be corrected, with special care taken regarding the armour and ammunition rack.
  3. As the 122 mm M-30 tank howitzer version passed trials, the commission deems it necessary to accelerate the mass production of the KV-9 tank.
February 16th, 1942"


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