Friday, 14 June 2013

Soviet Very High Power Guns: BL-9

I have previously written about the BL-8 152 mm Very High Power gun, and briefly mentioned the BL-9 Very High Power gun. Here is how both of these projects started. Surprisingly enough, they were originally meant not for the ISU-152, but for the SU-152. CAMD RF 81-12063-1 tells the interesting story.

"The special NKV telegram #5014 sent on September 24th, 1943, tasked OKB-172 and the #172 Molotov factory to develop a 122 mm self propelled gun, capable of reaching 1000 m/s muzzle velocity with a 25 kg shell.
Giving the highest priority to this project, OKB-172 completed the draft ahead of schedule, and presents it for your approval. As a result of performing the draft work, we have discovered the following:
  1. The task of creating an SPG with the muzzle velocity of 1000 m/s can be accomplished by installing a new barrel on the KV-14 SPG, to replace the model 1937 howitzer, and a new single-sided hydro-pneumatic balancing mechanism. 
  2. As the power of cannons constantly grows, you may be interested in our installation of an OBM-43 barrel, with the muzzle velocity of 880 m/s and a 43.5 kg shell, on the KV-14 SPG, instead of the 122 mm barrel with the 1000 m/s muzzle velocity. Such a solution raises the power of the SPG by 33.5% and increases its armour piercing and concrete piercing capability.
With this solution, not only does the SPG receive a more powerful gun, but the gun is already in use, and will ease production and use of the guns."

KV-14 is, of course, the pre-production index of the SU-152. 

The document then provides comparisons between the different gun options: the ML-20S, 122 mm OBM-50 (BL-9) and the yet unnamed 152 mm gun. The ranges at 22 degree elevation (max elevation for all guns) are: 12 km for the ML-20S, 21 km for the BL-9, and 18 km for the new 152 mm gun. The penetration for both experimental guns at 1500 meters is 195 mm against flat armour, and 160 mm against armour angled at 30 degrees. This is pretty close to the figures given in that other penetration table (197 mm against flat and 160 mm against angled armour). All three guns have the same horizonal traverse: +/-7 degrees. They can carry 16 shells (38 for the new guns with a redesigned fighting compartment). The projected rate of fire is 1.5 RPM for the ML-20S, 2 RPM for the BL-9, and 1.33 RPM for the 152 mm gun. The mass of the SPG is 47 tons with the ML-20S, and 48 tons with either of the new guns.

However, the OBM series wasn't only destined for tank destroyers. A 122 mm OBM-51 gun, almost equivalent to the OBM-50 (BL-9), was planned for a heavy tank. The project requirements were:
  • 1000 m/s muzzle velocity
  • 200 mm of penetration at 1000 meters
  • Use of existing A-19 shells
  • Maximum compatibility with ML-20S components
CAMD RF 38-11369-286: BL-9 against a 203 mm plate at 1000 meters. One shell penetrated completely, 4 shells are stuck in the armour, 3 shells left dents.

You may be thinking of the IS, but no, the tank that was first meant to carry this powerful gun was the KV. On October 26th, 1943, the Technical Department of the NKV held a meeting on the 122 mm OBM-51 tank gun proposed by OKB-172. The details are contained within CAMD RF 38-11355-1403.

"As ordered by the Tech-department of the NKV, OKB-172 developed a project for a modernization of the KV tank by installing a 122 mm gun. The modernization removes the current KV turret and all its armament, and replaces it with a new turret that holds a 122 mm high power gun, two machine guns, and the ammunition rack. The rest of the tank, all of its mechanisms, components, and armoured hull, including the turret ring, remain the same.

The 122 mm gun designed by OKB-172 has the following characteristics:
  1. Caliber: 122 mm
  2. Muzzle velocity: 950 m/s
  3. Shell mass: 25 kg
  4. Maximum gas pressure: 2660 kg/cm^2
  5. Barrel length with muzzle brake: 58.5 calibers
  6. Recoil resistance: 16 tons
The tank's turret consists of homogeneous rolled armour plates. Front: 75 mm, side: 60 mm, roof: 30 mm. In order to balance out the gun, the rear of the turret has 150 mm of armour. 

The gun is installed in the front of the turret on a welded mount. The mount and vertical aiming mechanism are borrowed from the SU-152 SPG with no changes. In order to balance the oscillating part of the gun, a hydromechanical balancing mechanism is planned. The turning mechanism is the same as in the KV turret. The tank carries 45 rounds of ammunition in the turret and on the bottom of the fighting compartment.

After discussion, we have come to the following conclusions:
  1. The modernization of the KV tank to equip it with a powerful 122 mm gun is a modern and reasonable course of action.
  2. The project is approved to continue to the prototype stage.
  3. It is reasonable to also adapt the modernization project, including the turret, to the IS tank.
  4. During development, it is suggested to:
    1. Use the D-5 mount, as it is the most compact.
    2. Use a horizontal sliding breech. 
    3. Increase the muzzle velocity to 1000 m/s on the IS chassis.
    4. Develop a cast turret variant, and make it as short as possible.
    5. Reduce the ammunition capacity to 30 shells to reduce turret height and mass.
    6. Allow for shooting on the move, move the fire button to the elevation mechanism. Implement a secondary electric fire mechanism.
    7. Reduce the tank mass to 45 tons.
  5. Give OKB-172 the highest priority, given the importance of this project.
  6. Suggest that OKB-172 work with naval armament factories."
As we already know, the lower velocity D-25T was chosen as the gun for the IS. Its penetration was entirely adequate for the German tanks that ended up being produced, and the high power 122 and 152 mm guns were ultimately not needed. 

18 comments:

  1. KV-1S with BL-9 (equivalent)?
    Yes, please, I'll take three. :)

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  2. Could make for a decent tier 7 premium heavy.
    good gun, but terrible manoeuvrability and worse armour.

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    Replies
    1. Not everything is about world of tanks you stupid cock

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    2. Fucking cucked

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  3. "BL-9 against a 203 mm plate at 1000 meters" and penetration ? 0_o
    Yes, please, I'll take one! :)

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  4. Excellent read, but one question come to mind:
    Would the KV chassis could even handle this massive turret and gun with it's recoil?

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    Replies
    1. That's why the KV version only reaches 950 meters per second.

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  5. so am I to understand that Germans tanks are total garbage while russian tanks > German tanks? please, do clarify

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    Replies
    1. I don't see how you could come to that conclusion by reading this article.

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    2. I read some of this blog (I think that's what you should call this impressive chunk of historical records)

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    3. German tanks like the Tiger and pnather had better guns at first but in general the soviets outproduced and out competed the German ones. German tanks were gas-guzzling complexities with bad manuverability and cross-country ability. Only uperior organization in the early stages of the war gave them the advantage.

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  6. soviet power gun is amazing, it is powerful and it is good for shooting and self defence.

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  7. I wonder, if the Germans had deployed the maus, would the IS version of the bl-9 have been used on the IS-2 or IS-3?

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    Replies
    1. Sorry, I meant OBM-51

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    2. Possibly, it it would likely end up only in tank destroyers, not in heavy tanks.

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  8. Perhaps the hardest test for any Russian patriot is to face the fact that it was RAF and USAAF + western allied navy forces which destroyed in 1943 some 25% of German war production. In 1944 they destroyed at least 50% plus 80% of German fuel production. So actually it was western allied who eliminated more than 35% of German war production before it started journey to battleground.

    In air war Lufwaffe losses were: 75% in west and south, 25% in eastern front. Putting those figures together we can be sure that for every 153 German aircraft aim to produce, 53 was eliminated by western allied air (and sea) power, 75 eliminated by western allied air power in combat zone (combat or operational losses) and only 25 eliminated by Soviet forces (either combat or operational losses).

    Soviet Union caused only about 16% of Luftwaffe total losses either in factory or combat level. So in reality when remembering how vital air power was - the war was won by western allied air and sea power, not by ragged hungry Soviet forces.

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    1. And don't forget that Germans used just about 12-13% of their AA-artillery in eastern front including Poland and Baltic states and that oil of Romania in early 1944 had only 13-15% share of German fuel production (for Luftwaffe even less).

      As you will notice there are lots of myths Russian Great Patriotic War Nonsense Factory is still feeding for ignorants. Perhaps the greatest shock will be when Russians finally realise how less big power actually put on land warfare. For instance Germans invested some 30% for land warfare, western allies some 20-25% and Japanese hardly more than 15%. Armies generally have always been much more backward than navies and air forces. Besides losses of army weapons and tanks were much easier and faster replaced than expensive navy vessels. It took much time and training to have skilful pilots too than some ordinary infantry men to those bulk divisions.

      So army losses were not decisive at all while lost battleships, aircraft carriers and well trained pilots were. Folks are too much focusing land battles.

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    2. airplanes cannot occupy & hold a land surface, ships cant do either.Navy can disrupt supply lines and isolate with a blockage an island or even a country, but STILL you have to put troops on the ground to take back this piece of land.Even if you destroy a country's military manufacturing capacity ,still you ll have to eliminate every pocket of resistance/defense of enemy ground troops.nd you cant do that with naval guns or flying tin cans straffing the ground with cannons rockets and bombs.US army had to fight japanese troops in caves and charge with bayonettes long after the Japanese military capacity was almost completely destroyed.War was won on the Eastern Front and on Land,deal with it.

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