2S35 Coalition

[Feanor]

It looks like the double-barrel SP-Arty project is continuing, and we have images of the prototype. The 2S35 Coalition-SV may yet see service.

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This project was reported cancelled last year, but it appears work is continuing, and quite possibly with state support.

Thoughts, opinions?

 

[NICO]

Thanks, great video.

 

[My2Cents]

Note that the video only shows one barrel being fired. The autoloader must be a monster. I doubt it would be practical or safe to be loading one barrel when the other fires. Vibration and barrel whipping from consecutive shots may limit the rate of burst fire as well.

It is probably a meter taller than the single barrel version and weighs 20% to 30% more.

To be honest, the design only seems to have an advantage if they are intending to fire 2 quick shots and then displace.

 

[Abraham Gubler]

I’ve been struggling for some time to understand the reasoning behind the twin barrel Coalition. Burst rate of fire is unlikely to be the motivation. It is easy enough to fire two rounds rapidly through a single barrel with a loading mechanism. The PzH 2000 fires a very rapid double tap by using the loading arm to pick up a second shell after the ordnance has been loaded which it holds above the breech. After firing it quickly loads the second shell and fires again within a second or two as soon as the gun has levelled after the initial recoil. With Soviet 152mm ammunition the propellant is held in a shell case making rapid two round bursts even easier (no problem with unburnt residue in the breech). Simultaneous firing may be possible but its going to put the two rounds on converge (hitting the same place) and not contribute to a frontage. Converge can be useful with different fusing (the best mix is one airburst, one point detonating and one delay hitting the same spot: not much can survive that) or to destroy a bunker (regiment converge: 24 rounds on 10 square meters!) but you can achieve all that with a single tube firing MRSI missions.

So why two barrels and all that extra weight and cost? Sustained rate of fire is probably the main reason. Any artillery piece is limited in its sustained ROF by the barrel’s ability to handle the temperature. With two barrels you are putting half the number of rounds through each barrel so the single unit can fire twice as many rounds for the same increase in barrel temperature. But you can achieve higher sustained ROF via active temperature management. The Crusader system had a very advanced barrel cooling sleeve that kept the barrel ‘cool’ during sustained fires. All the complexity and extra weight and cost of twin barrels seems a bit of a waste when you can just add a barrel jacket and run some liquid nitrogen up and down it. Even without active temperature management two gun systems is always better than one. So keep your Coalition I’d go for two SP guns.

 

[Feanor]

The official line is that it would have a higher rate of fire. Unofficially I have no idea what they're thinking. While it's true that the Msta-S is not a great arty piece, this is a ridiculous alternative. Hopefully we'll see more as time goes by.

 

[NICO]

I know very little about artillery and as far as I understand both PZ2000 and Crusader achieved pretty fast rates of fire without 2 guns. Could it be advantageous to have 2 auto-loaders if space is available so that you could fire 2 different types of rounds near simultaneously? Could there be some advantage to that?

I don't know how really to explain this but maybe with 2 guns, your extended rate of fire of 2S35 with 2 guns would be better than a rapid firing PZ200 with only 1 gun as it would overheat faster than 2 guns? You would have to forget about counter battery danger though.

Not sure it is a great system but sure looks bad ass.

 

[Locarnus]

Looks like the big brother of AMOS, prob. for the same reasoning.

And whats the issue with simult. firing? Two barrels would just double the rate of fire at some increase in weight.
Less exposure to counter fire...
Some guided munition and they land apart from each other, not in the same spot.

 

[My2Cents]

Looks like the big brother of AMOS, prob. for the same reasoning.

And whats the issue with simult. firing? Two barrels would just double the rate of fire at some increase in weight.
Less exposure to counter fire...
Some guided munition and they land apart from each other, not in the same spot.

If they fire simultaneously you have a major recoil problem.

As for increasing the rate of fire, you probably do not want to be in any part of the loading process for one barrel when the other one is fired. Any misalignment and everything smashes to a halt, if you are lucky. Smaller guns can handle this because they used fixed ammunition (projectile and powder in a casing are a single unit, like a rifle cartridge) and the lesser size and weight of the ammunition permit a larger (relative to the size of the round), and more rigid, ammunition handling and loading mechanism. All current 152mm/155mm howitzers use separate ammunition because of the difficulty of manually loading 140+lb rounds some 4 feet in length.

I suppose you could load both barrels simultaneously using a preloaded clip and semi-fixed ammunition. The practicality of this approach would depend where the bottlenecks are in the current loading processes for 152mm/155mm howitzers and the handling of the spent propellant casings. You would have to prepare and load 2 rounds into the clip, which would then be moved into position and then both rounds simultaneously rammed. However, ammunition storage space would probably increase by 60% to accommodate the propellant casings, and clearing jams and misfires would be extremely difficult. The length of the semi-fixed ammunition is also over 2x that of the components of separate ammunition, increasing the size of the loading and ramming mechanism by as much.

On the other hand, just going to a semi-fixed alone with a single barrel could increase the rate of fire by 60% to 80%, until cooling the gun barrel became a problem after 10 to 12 rounds. And probably weight a lot less.

 

[Feanor]

More on the Coalition, for those that can read Russian or use an online translator.

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Also the photo of an earlier prototype.

 

[Volkodav]

It could be to permit higher sustained rates of fire through allowing one barrel to cool while the other fires. Whether this is through firing alternatly or whether one barrel would fire for a couple of minutes and then switch to the other.

Another possibility could be a CRAM mission with the second barrel ready to arc up in the event of counter battery fire.

I missed the part of Abes post where he mentioned sustained rate of fire, whoops.

 

[NICO]

It could be to permit higher sustained rates of fire through allowing one barrel to cool while the other fires. Whether this is through firing alternatly or whether one barrel would fire for a couple of minutes and then switch to the other.

Another possibility could be a CRAM mission with the second barrel ready to arc up in the event of counter battery fire.

You seem to know more than me about artillery. Would it be advantageous to be able to fire let's say HE round on 1 target and maybe fire a precision round for counter battery on another target? How much vertical/horizontal separation could you get from 2 guns like this firing on separate targets? Not sure as a concept that it provides a big advantage over 2 separate guns, just asking. There has to be some reason Russians are spending money on this project.

 

[Feanor]

You seem to know more than me about artillery. Would it be advantageous to be able to fire let's say HE round on 1 target and maybe fire a precision round for counter battery on another target? How much vertical/horizontal separation could you get from 2 guns like this firing on separate targets? Not sure as a concept that it provides a big advantage over 2 separate guns, just asking. There has to be some reason Russians are spending money on this project.

The current size of arty bde's is rather small and few in number. In the even of a major war they are meant to serve as mobilization potential for more units. However in limited conflicts 18 tubes is in my opinion, not enough. The Coalition-SV would let them have more firepower with the same manpower and (theoretically) minimal cost increase.