Sunday, 2 July 2017

Howitzer KV

So called artillery tanks, or support tanks, appeared in the mid-1920s. The British pioneered the concept, equipping their Medium Tanks Mk.I and Mk.II with 94 mm howitzers. Similar tanks were also built in other countries. The USSR was no exception. The first work on artillery tanks in the USSR began in the early 1930s. The BT-7 Artillery was the best known vehicle of this type. The KV-2 can also be placed into the artillery tank category, with some leeway. The artillery tank concept was rejected by the USSR before the start of WWII. Nevertheless, the KV-9 was designed in early 1942, a tank that fully fit into the category of support tanks.
A child of the gun famine

Histories of the KV-9 are usually based on the post-war UZTM (Ural Heavy Machinebuilding Factory, Uralmash) report on its activity during the war. According to it, the design of a 122 mm artillery system was done "under factory initiative, with the goal of creating a more powerful tank gun than the L-11 or F-34 that our tanks used at the time." Various historians added fuel to the fire, claiming that the design of a 122 mm tank howitzer began in 1939, and a second attempt was made in the spring of 1941.

In reality, there was no interest in the M-30 as a tank gun in 1939 or especially in 1941. At the time, GABTU focused on increasing penetration, not high explosive action. The M-30 was not good in this department, especially considering the lack of armour piercing shells for it. Unsurprisingly, the gun was never considered for use in a tank.

Production of M-30 howitzers at UZTM. The existence of a production line influenced the choice of an alternative weapon system for the KV-1.

The summary of UZTM's work is viewed by many as a main and completely trustworthy source, but this is unwise. It was written in 1945, and some events ended up distorted through the lens of time and wartime chaos. It's enough to say that this document omits a large number of vehicles that were designed, mostly SPGs.

One of these distortions happened with the KV-9. The Artillery Committee journal entry dedicated to the testing of the KV-9's 122 mm howitzer shows how much this report reflects reality.

"In the fall of 1941, when the KV was being put into production at Ural factories, the issue of insufficient supplies of artillery systems was raised. Production of F-32 guns at the Kirov factory in Leningrad ceased, and the last producer of tank guns was factory #92 in Gorkiy, which mostly produced the F-34 gun for the T-34, and only began production of 76 mm tank guns mod. 1941 (ZIS-5) with 40 caliber barrels in October.

It was necessary to produce tank guns somewhere close to tank production in order to ensure continued production of KV tanks. It was necessary to consider the production of local factories first when solving this problem, since it was necessary to begin production of tank guns as quickly as possible. Based on this requirement, the NKTP technical council ordered the Uralmash design bureau to design and produce a prototype of a 122 mm mod. 1938 howitzer (M-30) into the KV-1."

As you can see, there is no mention of improving firepower in the entry. The Artillery Committee document reflects reality more closely. The first 17 ZIS-5 guns arrived at the Chelyabinsk Tractor Factory (ChTZ) in late September of 1941, and full fledged production began in October. ChTZ produced 27 tanks instead of 65 in September and 87 instead of 100 in October. Guns weren't the only limiting factor: there were also issues with supplies of V-2K engines and a large amount of rejected gears. Uralmash was also partially at fault: a report for October mentions that the factory did not produce enough gun mantlets.

The issues with engines, a direct consequence of the evacuation of factory #75, was partially resolved by organizing production of V-2 engines at the Ural Turbine Factory. On December 13th, factory #76 was organized here, and the first V-2K engines were shipped even earlier, in November. The Ural was starting to grow its own tank production center.

U-11 gun system, dated December 15th, 1941

Where did the M-30 as an alternative to the ZIS-5 come from? The answer to this question comes from the requirement to use the capabilities of local factories. Uralmash began producing M-30 howitzers in 1940. F.F. Petrov, the gun's chief engineer, arrived from Molotov (modern Perm) to organize production. He remained at Uralmash as the head of the design bureau. As you can see, there was no other choice for an alternative to the ZIS-5. The myth about improved firepower came from a different project, U-12. It was built from the 52-K 85 mm AA gun, production of which was evacuated from Kaliningrad (modern Korolev) to Sverdlovsk, along with the factory #8 design bureau.

Emergency backup

According to the Artkom historical report, the gun design was ready by late November of 1941. The factory design bureau's chief, F.F. Petrov, headed the project. L.I. Gorlitskiy, evacuated from Leningrad in October of 1941, was his deputy. These two men later became key figures in designing Soviet medium SPGs. V.N. Sidorenko, a veteran of Uralmash's gun production, was the chief engineer on the project. Engineers A.V. Usenko and N.V. Kurin also worked on the system, the latter of which also came from Leningrad. The project was curated by Zh.Ya. Kotin. In addition to overall direction of work on the KV, Kotin was the Deputy People's Commissar of Tank Production at the time.

Reorganization of UZTM's production lines which made factory #8 a separate entity. The production of ZIS-5 tank guns at this factory put an end to the mass production of the U-11.

The project presented at a meeting with Kotin came in two variants. The first variant of the U-11, had minimal changes to the oscillating part of the M-30. Sadly, there are no remaining images of this variant, but it was similar to what ended up in ZIK-11 and SG-122. Instead of a pedestal mount, the howitzer was installed in a frame and protected with a mantlet. This variant was simpler to produce, but it was completely unsuitable for a tank gun. For starters, the gun had a very complex and massive mantlet. The overall layout of the turret was altered, and its balance was thrown off. It's not surprising that this variant was rejected.

The second variant of the U-11 was more difficult to produce. The M-30's barrel and breech remained, while the pipe was changed and the recoil mechanisms were designed anew. However, even from a production standpoint, it wasn't as bad as it could have been. The overall design was quite simple, and the components that had to be manufactured were tailored to the factory's capabilities. The most important thing was that the turret did not have to be changed significantly,

KV-9 at the factory, January 1942.

As a result of the meeting, the more compact and appropriate variant was selected.

"The technical meeting made a decision that can be summarized as follows. The Uralmash design bureau will create a technical project based on the draft and produce one prototype. Considering the lack of armour piercing shell, size of the ammunition and limited amount of space for it, drastic drop in rate of fire, and other negative consequences, the technical meeting made it clear that this option is viewed as a reserve, emergency measure."

It's not hard to see GAU's opinion of the project. The main reason for it was that the peak of the "gun famine" had passed. In addition, after the evacuation of factory #8 to Sverdlovsk, the ZIS-5 would be produced not only in Gorkiy, but at UZTM. This decision was finally confirmed by GKO decree #1070ss "On building NKV factory #8". The launch of production was late, but Chelyabinsk tanks were equipped with Sverdlovsk guns starting in January of 1942. Compared to this, the new gun with a lower rate of fire, unclear penetration, and a need to change the turret was less attractive.

The same tank from the front.

Despite such grim conclusions, the U-11 project moved past the draft stage. Technical documentation was ready by December 15th, 1941. A.S. Schneidman was involved from the ChTZ side as the man responsible for the KV's armament. The gun fit into the turret, but the gun port, mantlet, and observation devices were changed. The calculated maximum gun depression of the U-11 was -3.5 degrees. The recoil mechanisms did not allow for making it any greater.

KV-9 from the left.

The U-11 was built in metal and tested on a stand by the end of December of 1941. Later, when the gun mantlet was finished, the system was sent to Chelyabinsk to ChKZ. Tank #4996, built in Leningrad and put through refurbishment, was selected as the recipient. According to documents, the tank fought in the 121st Tank Brigade before it ended up in Chelyabinsk. The U-11 was installed into a cast KV turret with the rear machinegun still in place. Overall, the gun fit into the turret, but the gun depression was even less than on paper: -2 degrees. The ammunition capacity was planned at 50 rounds, but in reality was slightly less, at 48 rounds. To compare, the stock ammunition capacity of the ZIS-5 was 114 rounds. The amount of ammunition carried for the machineguns was also less: 1943 instead of 3000. The converted tank was given the index KV-9.

False start

Overall, ChKZ's treatment of the KV-9 was neutral, if not cold. The factory's design bureau had no direct relationship to the project. In addition, SKB-2 had two projects of higher priority: KV-7 and KV-8. The KV-7 was designed at Stalin's personal request, and factory #200 built 20 hulls before it was even tested. Finally, the tank was rejected and sent to be refined, and the factory had many unused hulls lying around. All of this slowed down work on the KV-9.

The same tank, showing maximum gun elevation.

On January 23rd, 1942, the test program of the "122 mm gun on the KV-9" was finalized. 206 shots would be fired, 150 of them with an increased power shell to test robustness and 30 to determine precision. A 50 km march was also planned to test the travel lock, convenience of mechanisms, loss of calibration, reliability of the ammunition rack, and crew comfort. Order #012 was signed on the next day, instructing that the trials would be done at the Kopeysk proving grounds from January 26th to February 5th. The order also formed the trials commission.

The turret is turned backwards.

In practice, the trials shifted, and were performed from February 2nd to 11th. 210 shots were fired, 171 of them at the factory proving grounds with proof and increased power shells. The recoil length of 560-580 mm was considered normal. Air samples taken to establish the concentration of gases in the turret were also within norm. Firing at a 5x5 meter target at a range of 1 km was a success: all shells hit the target. Trials to measure precision when shifting fire were also successful: at a range of 600 meters, all 1.25x1.25 m targets were hit.

In addition, trials were held at factory #200 to determine penetration. Since the M-30 had no armour piercing shells, they were taken from the A-19 122 mm corps gun. 4 shots were fired at a cast KV-1 turret from a range of 100 meters. The propellant charge was increased with every shot (from 2100 to 2400 grams), and the muzzle velocity went up from 525 to 573 m/s. The first and fourth shells penetrated the turret and ended up inside, the second and third ricocheted, knocking out a plug.

These were impressive results, but there were also complaints. In addition to the poor gun depression, the rate of fire was only 2 RPM. There were also complaints about the loader's station. The commission demanded that the gun mantlet be improved. There were also other drawbacks.

The turret is turned to the left.

Despite the drawbacks, the commission's conclusion was positive:

  1. The KV-9 tank with the M-30 howitzer passed trials and can be accepted into service with the Red Army.
  2. When building an experimental batch of KV-9 tanks, it is necessary to make all changes regarding the drawbacks of the prototype, paying special attention to the armour of the gun and the ammunition racks.
  3. Since the 122 mm M-30 tank howitzer trials gave good results, the commission considers it necessary to accelerate mass production of the KV-9."
Factory #8, which was separated from UZTM in February of 1942, began preparing for the initial batch of U-11 tank guns. In the meantime, some serious discussions broke out between the GAU and the NKTP. The Artillery Committee's review of the trials revealed a nuance. When firing armour piercing shells, the pressure inside the chamber reached 3500-4000 kg/cm² at a stock value of 2350 kg/cm². This was unacceptable, and intensive firing of these shells could result in failure of the breech. When an acceptable propellant load was used, the muzzle velocity was only 432 m/s. As a result, the penetration of the U-11 was worse than the ZIS-5. The only advantage of the U-11 was the high explosive performance. The GAU Artillery Committee considered it unnecessary to install the U-11 into the KV-1, reminding the NKTP that this was built on their own initiative.

Damage of an armour piercing shell after hitting a KV-1 turret.

On April 2nd, 1942, trials of high explosive shells against armour plates were performed. The M-30 gun was used instead of the U-11, since their ballistics were the same. Trials against a 76 mm plate showed that it it not damaged when hit by a 122 mm HE shell. The trials stopped here. This meant the end of the KV-9. The issue of mass production was no longer mentioned.

A number of researchers claim that the KV-9 was not put into production because of excess weight. As you can see, that is not the case. An attempt to reanimate the KV-9 was made in October of 1942, but that attempt was unsuccessful.

Paper reserve

By the time the trials of HE shells against armour were performed, factory #8 began production of the pilot batch of U-11 guns. As a result, the story of the KV-7 repeated itself. This time, instead of 20 hulls, there were 10 howitzers with no purpose. A decision had to be made regarding what to do with these systems.

U-22, an attempt to install the U-11 into a T-34 turret.

When work with a heavy tank went badly, a decision was made to turn to the T-34 medium tank as a platform. Mass production of the T-34 at factory #183 in Nizhniy Tagil had just begun in the spring of 1942. NKTP approved the cooperation of factories #8 and #183. The resulting system was indexed U-22 and differed slightly from the initial design. The turret had to be altered slightly to fit the larger weapon. The mass of the "artillery tank" was 30.7 tons, which was about the same as that of a regular T-34.

Factory #183's howitzer T-34.

The project ended up at the Artillery Committee in July of 1942. The response was as expected:

"The project installs a 122 mm U-11 tank howitzer into a new T-34 turret, with preservation of the existing turret ring. Considering that the fighting compartment only fits two people, which is not enough to properly service the gun, this project is of no interest and must be declined. Since the installation of this gun into the larger KV turret did not result in satisfactory comfort of service and rate of fire, the development of this project is nonsensical. 

In order to avoid further unproductive waste of time and effort, the Artillery Committee considers it prudent to consult the GAU on further work that stems from personal initiative."

It's hard to argue with the artillerymen. If the KV-9's rate of fire was only 2 RPM, it would be even lower here. A number of researchers considered this vehicle to be the ZIK-10 SPG, but the letter specifically refers to a tank. 

One of the last photographs of the KV-9, spring of 1942.

This was not the last attempt of finding a home for the U-11. In August of 1942, factory #8's design bureau, led by Petrov, designed the ZIK-10 SPG that had the same U-11 as its armament. Even earlier, in July of 1942, factory #592 designed the SG-122U SPG with the same gun. These designs did not move past the drawing board, even though the GABTU kept trying to find a use for the rather good U-11 gun. As for the KV-9, it was parked at ChKZ's courtyard in June of 1942. In December of 1943, the tank was scrapped.

No comments:

Post a Comment