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Hello, and welcome to my suggestion for the KV-9
TL;DR: A heavy tank prototype based on the KV-1 to solve the issue of a lack of 76mm F-32 and (later) the ZiS-5 cannon. Up-armored and equipped with a modified 122mm howitzer.
For a more in-depth look:
In-Depth Background
The KV-9 can trace its production origins to mid-late 1941. With the beginning of Operation Barbarossa, Soviet factories were kicked into high gear in order to produce enough tanks and weapons for the war effort. Issues, as always, caught up to the Soviets on this end. With KV-1 tanks being produced in factories further east like UZTM (Ural’s’kiy Zavod Tyazhelogo Mashinostroyeniya,or Ural Heavy Machinery Plant) in the Ural mountains, there were supply issues when other factories failed to produce what was required. For UZTM, those supply issues were related to the lack of 76.2mm anti tank guns. With the siege of Leningrad imminent, the Kirov plant had halted production of F-32 cannon for the KV-1. The only remaining producer of tank cannon, then, was the Gorkiy factory - who was dedicated to production of the F-34 gun for T-34s, not yet adapted for KV-1s.
With no set-in-stone date by which cannon production would begin again, and a need for continued KV-1 production, the NKTP (Narodnyi Komissariat Tiazheloi Promyshlennosti, the People’s Commissariat of Heavy Industry) hoped to find a replacement as soon as possible and as close to UZTM as possible. Luckily, while not a producer of tank cannon, UZTM had produced the M-30 122mm field howitzer since 1940. Hoping to take advantage of this, UZTM’s design bureau was asked to diagram a turret for the KV-1 that would be able to house a tank-adopted variant of the M-30. Alongside this, UZTM also started producing the V-2K engines needed for the tanks, making the plant an even better candidate for production of stopgap KV-1s armed with something other than the F-32 or ZiS-5.
The gun itself would further be developed. The original designer of the M-30 howitzer (and an incredibly proficient cannon designer), Fyodor Fedorovich Petrov, actually headed the project to adapt the M-30. Alongside him were such notable figures as Lev Gorlitsky and Deputy People’s Commissar of Tank Production Josef Kotin. The assembled “team” came up with 2 major designs in the end, both given the new designation “U-11”. The 2nd design was chosen for a multitude of reasons - it was simple, the parts required were able to be produced at UZTM, and most importantly, it was compact enough to fit into a minimally modified KV-1 turret. Even with the advantages and work put into it, the gun still suffered some drawbacks. It would have a much slower rate of fire, its storage capacity would be significantly lower, and there was no purpose built armor piercing or anti-tank shell for the weapon. Most importantly, several factories (including UZTM) had started production on the ZIS-5 anti-tank cannon for the KV-1, reducing the need for an intermediary cannon. Despite all this, the possible urgency of the situation and extent of development pushed the authorization of one prototype.
By December 15th, the tank was fully blueprinted. The cannon managed to fit inside the turret with little modification, but the gunport and mantlet had to be changed. The U-11 cannon itself had the first prototype constructed by mid December, and the gun, its improved mantlet, and optics were placed into one of the more rare cast KV-1 (1941) turrets, which was similarly placed on a KV-1 (1941) hull modified to carry 122mm shells inside. Some small issues came to light when this pairing was made - the U-11 was unable to make the expected 3.5 degrees of depression and instead made only 2, and only 48 main gun shells were able to be stored, compared to the expected 50. After the prototype itself had been completed, it was sent to ChTZ (Chelyabinskiy Traktornyy Zavod, or Chelyabinsk Tractor Plant) for further testing.
(Note: Several sources say that the single prototype fought as part of the 121st Tank Brigade on its way to ChTZ.)
In January and February of 1942, a trial was set up and performed specifically for the KV-9. 210 shots, most with an above standard charge weight, were fired to test recoil, gun pressure, and gas leakage. All that were tested came back normal, and the gun managed to successfully pass the gunnery trials too, hitting each shot on both a 5x5m target at 1km and a 1.25x1.25m target at 600m. At this point, the tank was also provided with armor-piercing shells. The M-30 and U-11 had no AP shells by default, but the cannon was provided with APHE shells from the A-19 M1931/37 field gun. These shells, fired with an increased muzzle velocity for testing, succeeded in penetrating a KV-1 turret face from 100m. However, it was found that the APHE shells with such a velocity put significant strain on the barrel, with the maximum safe velocity being 432m/s. Alongside this, the trials also showed a very decreased reload rate of around 2 rounds per minute and some armor issues with the mantlet. Regardless, the tests were considered a success.
In the end, it was not to be. It was found that the decreased velocity of the AP shell significantly worsened penetration, to the point where a standard 76.2mm AP shell from a ZIS-5 would surpass it. The final nail in the coffin came when the 122mm HE shell was tested against armor - and promptly failed to do significant damage to a 75mm armored plate. Even though the testing commission found it “…necessary to accelerate mass production of the KV-9” after initial trials, the consequences brought about by the large howitzer (limited ammunition and worsened reload) were no longer dampened by the power of the U-11 howitzer, which in theory actually performed worse against armored targets than the ZIS-5. Had the ZIS-5 still been in deficit, the howitzer might have been justifiable for tank use, but the production of the ZIS-5 at UZTM made the entire reason for continuing development of the U-11 and the KV-9 itself pointless.
The singular prototype was finally scrapped in December 1943. Interestingly, the BP-460A HEAT shell for the M-30 would have come out before the tanks’ scrapping, significantly increasing the power of its main gun. However, it is safe to say that it was clearly not enough to save the KV-9.
Construction:
- Builder: Ural’s’kiy Zavod Tyazhelogo Mashinostroyeniya
- Ordered: early December 1941
- Completed: late December 1941
- Length: 6.9m
- Width: 3.32m
- Height: 2.71m
- Weight: 48.1 tons
Powerplant: Kharkiv model V-2K diesel engine, 600hp at 2,000RPM
Speed: 35km/h
Crew: 5
Armor:
- Hull: Reportedly 135mm front (unable to confirm), 75mm sides, 60mm rear, 40mm roof
- Turret: 75mm face, 90mm mantlet layered on top of that, 75mm sides, 75mm rear, 40mm roof
122mm U-11 howitzer, 48 rounds
- 122mm OF-462 high-explosive shell: 21.76kg, 515m/s, 3.67kg TNT
- 122mm BP-460A high-explosive anti-tank shell: 13.4kg, 335m/s, 2.73kg TNT equiv, 160mm pen
- 122mm BR-471 armor-piercing high-explosive shell: 25kg, 432m/s, 246.4g TNT equiv, 86mm pen (according to DeMarre formula and using current WT figures)
3x 7.62mm DT machine gun (bow, coax, and rear of turret), 1943 rounds
I hope my post has been interesting in the least, and I hope you consider voting to add this unique tank to War Thunder.
Yours Truly, KewlPangolin.
Sources:
Tank Archives - Howitzer KV ← Best source out of the bunch.
Tank Archives - The First Coming of the IS-2
Catainium’s Tanks - KV-9
Tank Archives - DeMarre Penetration Calculator
Shell specifications (mostly) provided by our very own War Thunder