Intro:
The M55 howitzer is yet another fantastic addition to the American howitzers collection, with a lot of other nations benefiting from this addition as well. The Soviets however haven’t received a proper counterpart yet, so that’s what I’m here to propose: the S-51 203mm self propelled gun!
History:
At the end of 1942 the USSR’s defensive campaign started turning into an offensive campaign, and one of the army’s aspects that was found lacking was it’s ability to properly deal with pillboxes or heavily fortified positions.
Even the 152mm howitzer was (somehow) sometimes not enough, but another gun was: the 203mm M1931 B-4, but this weapon was slow, clunky, and had no protection whatsoever.
The regular towed 203mm M1931 B-4 Howitzer
A new assault vehicle was needed, and the Central Artillery Design Bureau (TsAKB) came up with the S-51. The previously mentioned B-4 203mm gun now mounted on a KV-1S hull, with a single prototype being made in 1944. However, due to the vehicle getting knocked back well over a meter when firing, often knocking over a lot of the crew on top of the vehicle, along with other stability issues, it was concluded the KV-1S was an insufficient platform for carrying such a large gun, and thus was never accepted for production.
This Vehicle’s Place in the Game:
This is one of the most unique vehicles Gaijin has yet to add. I strongly doubt this thing would be good at all, but it for sure would be a lot of fun. This is why I believe this would fit best as an event vehicle: very fun, but not competitive. The battle rating I think matters quite little, seeing how strong the gun is and how literally anything can easily kill it. I would personally place it around 3.7 to 4.3, as this is a similair BR to comparible German open top SPGs, and this way you could also play it allongside other Soviet KVs.
Now there are a couple of things that would have to be somewhat artificially altered for this vehicle to be functional in game. Namely, the reload is quite long, and some of the crew were placed on the ground next to the vehicle when operated. Altering the reload Gaijin has done before with the Sturmtiger, so I doubt that’d be a problem, especially considering the change wouldn’t nearly as large as that of the Sturmtiger. Regarding the crew, I would try to fit as many of them onto the vehicle itself, or otherwise just outright leave the extra crewmembers out (trust me, this vehicle has enough). I think these changes are well worth the vehicle!
Specifications:
Hull armour: Regular KV-1S (The KV-1S hull is largely untouched, apart from a new engine, the new gun mounting, walking platforms, ladders, and railings being added)
Gun shield armor: 7mm
Weight: 49.7 tons
Engine: Model V-2K 12 Cylinder Diesel engine
-600hp at 1900rpm
Transmission: Same as KV-1S
Speed: 30 kph
Crew: 10
-Driver
-Commander
-Gunner
-Loader x7 (or less, dependent on how many are placed on top of the vehicle)
-loses assistent driver, as well as acces to hull MG
armament: 203mm howitzer M1931 (B-4)
Horizontal guidance: +4 degrees to each side
Vertical guidance: 0/+60
Ammunition:
*F-265
-Capped HE, 100kg, 288 to 607 m/s depending on propellant charge weight
*F-265D
-HE, 100kg, 288 to 607 m/s depending on propellant charge weight
*G-620
-Anti Concrete, 100kg, 607 m/s
-102mm of pen, 500 meters, 27 degrees (178mm max pen according to calculator)
*G-620 T
-Anti Concrete, 146kg, 607 m/s
-102mm of pen, 1800 meters, 27 degrees (216mm max pen according to calculator)
Both high explosive shells could have a varying muzzle velocity, depending on how much propellant was placed behind them. This could range from 3.24 kg (288m/s) all the way up to 15.0-15.5 kg (607 m/s), though I would go for the higher end for a consistent velocity with the AC shells. Alternatively, the uncapped HE shell could be given the lower velocity (maybe with a lower reload time as well), with the capped shell the higher velocity.
As mentioned, the regular F-265 shell is capped allowing for more penetration. I couldn’t find the explosive filler in these shells, but considering they’re 100kg in weight total, I doubt it matters much in terms of performance. For reference the KV-2’s OF-530 HE shell is only 40kg in total weight.
There are also 2 AC shells, which unlike the KV-2’s, might actually be usable. Unlike the HE shells, these have a fixed velocity.
The G-620 “Light Anti Concrete” shell can according to a quick calculator go through about 178mm of armour at most, but according to real life tests only through 102mm at 500 meters on a 27 degree angle. My estimate 0 degree, 10 meter penetration number would be somewhere in the middle, around 130 to 150mm of penetration. This would of course have to be properly calculated, but keep in mind that like the KV-2’s shells there is a limit where the penetration doesn’t go down any further due to the sheer explosive mass.
The G-620 T “Heavy Anti Concrete” shell would be very strong, and by using the same logic as the previous shell, I think would have between 160 to 180mm of penetration at 10 meters at 0 degrees.
The S-51 could carry a total of 12 shells, which were placed in a wooden box behind the right gun shield attached to the railing as seen in the picture below. Technically the ammo box would only be attached here during traveling, but seeing as you’re gonna do a lot of this in-game, I think it makes sense to just place the box here. You could make it so you’d have to set-up in a firing position, placing the ammo box on the ground and dismounting the externally placed crew (which would fix that problem), but I think this would be way too tedious. I’d rather have less crew over having to stand still for a very long time just to reload.
Speaking of which, and as previously mentioned, the reload is quite long for in-game purposes. The fire rate is stated to be about 1 shell every one and a half minutes (90 seconds), which would be excesively long in-game, especially considering how vulnerable the vehicle is compared to other vehicles with extreme reloads like the KV-2, Sturmtiger, or T-30. I would half the reload rate to about 40 to 50 seconds, which is pretty in line with the Sturmtiger.
Conclusion:
I truly believe this could be one of the most fun and ridiculous vehicles in the game, and even with the minor tweeks needed, this would be a well worth vehicle to have in-game. Let me know what you think though, this is my first ever vehicle suggestion so any and all feedback is welcome. Below I’ll leave some more picture as well as my sources. God bless!
More images:
Spoiler
Bellow are images of the S-51 with the gun in travel position
Sources:
Spoiler
Tank Archives: High Caliber Convertibles
Tank Archives: Penetration Calculator
Tank Archives: Penetration, Part 3.
Работы по опытным САУ, начало июня 1944 года: yuripasholok — LiveJournal
Translated sources:
- Yes
- No
- In the tech-tree
- As a premium (wrong answer)
- As an event vehicle
- As a squadron vehicle
- In a battlepass
- I don’t want this vehicle being added