Tuesday, 23 September 2014

KV-9 Rejection

"According to the resolution of the GAU KA chief, Colonel-General of Artillery, comrade Yakovlev, I report the conclusion of the GAU Artillery Committee on the 122 mm U-11 howitzer in the KV-9 tank.
  1. The report given to the commission is not full. We have yet to establish the accuracy and expected deviations, recoil velocity curves (due to new recoil mechanisms, different from the stock 122 mm mod. 1938 howitzer), establishing the ballistics when firing AP shells, and testing penetration with stock shells.
  2. The rate of fire, range, accuracy, ammunition capacity, and ease of use of the 122 mm howitzer are inferior to the 76 mm tank gun.
    As for the penetration of 110 mm of cast KV turret armour when firing a 25.2 kg shell at a muzzle velocity of 525-573 m/s at 100 meters, calculations show that firing at this velocity is unacceptable, as the pressure in the barrel reaches 3500-4000 kg/cm^2. Due to the screw breech, it is not possible to increase the pressure in the barrel. The pressure of 2350 kg/cm^2 must be maintained, and this would require a charge that provides a muzzle velocity of 476 m/s or use the first charge of the M-30 howitzer, providing a velocity of only 432 m/s. In either case, the penetration of the AP shell will be less than the 76 mm gun. The only advantage of the M-30 howitzer in a KV-9 instead of an F-34 gun is the improved HE performance.
  3. As the 76 mm gun adequately deals with all tasks required of tank artillery, using a 122 mm howitzer in a KV tank is excessive.
  4. The installation of a 122 mm howitzer in a KV tank is initiated by the manufacturer as a reserve in the event of a shortage of 76 mm tank guns. From this point of view, it is reasonable to complete trials, after which a finished prototype and blueprints for it will be developed, according to commission conclusions. 
Additional trials of 80 shots are scheduled at the Nizhniy Tagil artillery proving grounds. I ask for you to order the KV-9 tank with a U-11 howitzer shipped to Nizhniy Tagil for these trials. Notify the Artillery Committee when the tank is shipped so that we can send a representative to the proving grounds."


CAMD RF 38-11355-668

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