Partial Penetrations Are Broken

[cb4]

It doesn't seem possible to protect a battleship adequately against guns larger than 17 inches. If you armor your ship sufficiently to resist AP, the AI will always shoot HE, and HE partial penetrations do significant damage, even against very thick armor. The partial penetration damage scales up rapidly with caliber, and once you're facing 20 inch guns, HE partial penetrations do so much damage they can knock out main battery guns that have 50 equivalent inches of armor plate, as well as damage engines behind similarly massive main belts.

In this scenario, the enemy super-battleship has dealt almost as much damage with 11 20 inch HE partial penetrations as my battleship has with 22 18 inch AP full penetrations, and has knocked out two engines and a main battery turret.

As a side note, the power of these HE shells also means you cannot go the all-or-nothing method, even if you keep all of your magazines inside the middle 3 sections that are protected by the main belt. 20 inch HE will never overpen and if it actually gets a full penetration in your bow or stern, it will wreck half your ship and splash damage everywhere, including in your main belt sections. You need around 8 equivalent inches of armor protection to prevent a 20 inch HE full penetration.

[disc]

We definitely need a testing mode, this is a curious phenomenon

[madham82]

How exactly do you know the AI is using HE? Judging by your damage screenshot it looks like you are using HE (17 fires), but the AI has only 1 fire? Seems like it is using AP. Makes me wonder if we can rely on the visual difference between HE/AP for the AI. Also the avg and effective pen numbers are reversed in comparison, though it does look like the AI's hit had far lower armor pen in the bottom line, but much higher in avg armor pen? That doesn't make any sense. 

[Cpt.Hissy]

They used WoWS model, HE are yellow-ish tracers and AP are white.

 

On topic, theoretically stupidly big guns will be devastating to anything, be it armored or not, simply because of bigness of boom.
but i don't know the scale of that devastation and how it corresponds to what happens in game.

Edited March 21, 2021 by Cpt.Hissy

[cb4]

40 minutes ago, madham82 said:

How exactly do you know the AI is using HE? Judging by your damage screenshot it looks like you are using HE (17 fires), but the AI has only 1 fire? Seems like it is using AP. Makes me wonder if we can rely on the visual difference between HE/AP for the AI. Also the avg and effective pen numbers are reversed in comparison, though it does look like the AI's hit had far lower armor pen in the bottom line, but much higher in avg armor pen? That doesn't make any sense. 

The numbers are correct. They are shooting HE (yellow tracers), and HE has very low effective pen (only around 7 inches for 20 inch HE shells). If they were shooting AP we would see over 20 inches of effective pen, and they would get full penetrations against belt extended/deck extended. They are hitting my armor which has between 9.2 and 50 inches of effective armor, so averaged out among all the hits 27.7 inches of effective armor is realistic.

On the other hand, against their ship, I am shooting 18 inch AP against relatively thin armor (and penetrating it), so I'm getting 22.8 inches of effective pen on average, against an average of 10.9 inches of effective armor.

I think the reason I have more fires is I have twice as many hits, and they are actual penetrations which seem to cause more fires.

[madham82]

15 hours ago, cb4 said:

The numbers are correct. They are shooting HE (yellow tracers), and HE has very low effective pen (only around 7 inches for 20 inch HE shells). If they were shooting AP we would see over 20 inches of effective pen, and they would get full penetrations against belt extended/deck extended. They are hitting my armor which has between 9.2 and 50 inches of effective armor, so averaged out among all the hits 27.7 inches of effective armor is realistic.

On the other hand, against their ship, I am shooting 18 inch AP against relatively thin armor (and penetrating it), so I'm getting 22.8 inches of effective pen on average, against an average of 10.9 inches of effective armor.

I think the reason I have more fires is I have twice as many hits, and they are actual penetrations which seem to cause more fires.

Yea tracers are the only way I knew of too, but something is seriously off. How can the average effective pen be so low but average armor pen be high? Either something is making the splash damage from HE way more effective or those stats need to be explained. 

At least with your AP numbers, it seems to make sense. On average your hits pen effectively 22" of armor, but the hits are on average are against 10" of armor. That's completely opposite the way the HE is being represented. HE can't effectively pen less armor per hit than it pens on average. That seems to imply it damages armor around the hit more than the point it hits. Would explain your issue if actually true. 

[Zuikaku]

So, after insisting on having stupidly oversized and unrealistic guns and hulls in the game ,now we complain about unrealistic damage they inflict??! 

Too much energy and effort has been put in this fantasy stuff anyway, especially when we lack early hulls and guns that actually existed.

[Entropy Avatar]

On 3/21/2021 at 5:08 AM, cb4 said:

As a side note, the power of these HE shells also means you cannot go the all-or-nothing method, even if you keep all of your magazines inside the middle 3 sections that are protected by the main belt. 20 inch HE will never overpen and if it actually gets a full penetration in your bow or stern, it will wreck half your ship and splash damage everywhere, including in your main belt sections. You need around 8 equivalent inches of armor protection to prevent a 20 inch HE full penetration.

The splash damage part is interesting. My understanding is that if a large HE shell exploded in unarmoured forward part of the ship, the internals would still be protected by a transverse armoured bulkhead. Is armor only used for penetration calculations and not to protect against the actual explosions?

[madham82]

2 hours ago, Entropy Avatar said:

My understanding is that if a large HE shell exploded in unarmoured forward part of the ship, the internals would still be protected by a transverse armoured bulkhead. 

That's actually an improbability (won't say impossible) because HE fuses on contact. Therefore if it hit something substantial enough to fuse it (i.e. the side of the hull), then it wouldn't explode inside (like AP) but the on the outside. Then the only damage internally would be from splitters that had enough energy to continue on in the hull. 

Edited March 22, 2021 by madham82

[Zuikaku]

Large HE shells were known for knocking out heavily armoured Panthers and Tigers. The sheer power of explosion and forces of resulting pressure were enough to demolish and displace turrets without penetrating the armour. And incapacitating crew in the process.

[Cpt.Hissy]

Large naval shells were known to knock off main belt plates, cause cracks and deformations in the hull, pop out rivets and create leaks, even when they failed to detonate.

it's literal ton of steel traveling at supersonic speed. It's much more impact force than any tank in existence ever could have. (well unless you shoot a tank itself)

And big HE detonating on the hull will not just scratch the paint or create splinters, it will tear out huge part of the plating and leave a hole big enough to drive through with a bus.
There is a reason behind the distributed armour idea.

[madham82]

I was not speaking to hull without armor, I was pointing out HE does not blow up inside the hull. Thats AP. The damage HE can do is directly related to the thickness of the armor and the amount of explosive used. But a shell that explodes inside a sealed area does far more damage than one on the outside. Hence the use of AP. 

[Zuikaku]

Blast effect of shell this size is is well felt on the inner side of the armour. It is wrong to think that detonating of several hundred kilos of explosives on the face of the armoured plate will leave the compartments behind undamaged. 

[cb4]

Japan 51 cm/45 (20.1") "A" Type 98 (?) - NavWeaps

The bursting charge of the 20 inch HE shell intended for the A-150 'Super Yamato' would have been 84kg. Not... hundreds of kg.

There are actual data and formulae on how much armor is required to defeat an HE shell.

Okun Resource - Miscellaneous Naval-Armor-Related Formulae - NavWeaps

This formula suggests that a 20 inch nose-fused HE shell could, at most, assuming a point blank impact at 90 degrees at 2300 fps (basically muzzle velocity), blow a 20 inch hole in a 6.8 inch plate of STS homogeneous armor, and that a 8.16 inch plate is the maximum thickness that would be cracked or dented. (Yes, I realize that the armor in the game would be face hardened, but I don't think it makes a huge difference here).

Based on this I would expect a 4.6 inch plate to end up with a ~30 inch hole. As for the 25 inch belt... I wouldn't expect any damage at all. This is generous as we're not talking about point blank, 90 degree impacts, this was an engagement at around 20 km where the shells would be striking much closer to 45 degrees and would been slowed by air drag.

There's a reason that AP was used - HE is just not very effective against heavy armor. If HE shells were able to cause significant, incapacitating damage to battleships without penetrating, battleships would have been built with very different armaments and protection schemes.

In no way should 11 20 inch HE partial penetrations (several of which hit the strongest part of the protection scheme - a protection scheme far stronger than any ever constructed) be able to put a 75,000 ton battleship in serious danger of sinking due to structural damage. Battleship protection schemes were designed to protect propulsion, steering, the main armament, ammunition, and enough reserve buoyancy to keep the ship from sinking from anything short of an AP shell, AP bomb, or torpedo that was actually powerful enough to penetrate.

From HE shells, I would expect damage to the less armored areas, and a superstructure hit to seriously mess up fire control and spotting, but currently in the game, you can *sink* a battleship with HE without ever penetrating its armor. There is no way that is reasonable.

[Entropy Avatar]

13 hours ago, madham82 said:

I was not speaking to hull without armor, I was pointing out HE does not blow up inside the hull. Thats AP. The damage HE can do is directly related to the thickness of the armor and the amount of explosive used. But a shell that explodes inside a sealed area does far more damage than one on the outside. Hence the use of AP. 

My interest is mostly how the damage model in the game works. I'm wondering if it's possible that when HE does damage to an unarmoured portion of the hull, does the "splash damage" to neighbouring portions of the hull take armour into account. As you say, the thickness of the armour should have an effect on the spread of damage from one part to another - but that won't happen unless it's explicitly coded in the damage model.

Overall, I get the sense that the dev's use armour to determine penetration level but perhaps haven't considered all of the effects.

[madham82]

46 minutes ago, Entropy Avatar said:

My interest is mostly how the damage model in the game works. I'm wondering if it's possible that when HE does damage to an unarmoured portion of the hull, does the "splash damage" to neighbouring portions of the hull take armour into account. As you say, the thickness of the armour should have an effect on the spread of damage from one part to another - but that won't happen unless it's explicitly coded in the damage model.

Overall, I get the sense that the dev's use armour to determine penetration level but perhaps haven't considered all of the effects.

It's a good question. I know there was a fix made a couple of patches ago to fix some issues with HE. Basically plunging fire HE was going through the deck like butter and doing orders of magnitude more damage than AP would at the same distance. This made it possible to sink well protected ships in just a few salvos. It sounds like all the issues might not have been solved completely. It definitely sounds like the "splash" damage is greater than the immediate area the HE shell impacted, which shouldn't be so. 

Edited March 23, 2021 by madham82
typo

[Cpt.Hissy]

Damage model in the game looks like that of WOWS, except we don't have complex internal armour model and realistically placed hitboxes for components, but out armour is hull's outer surface with very generic separation into parts, and internal systems are either represented by generic, evenly placed hitboxes, or are just pure RNG

Don't expect much from it..

[Hangar18]

On 3/21/2021 at 5:08 AM, cb4 said:

It doesn't seem possible to protect a battleship adequately against guns larger than 17 inches.

sounds about right.

[madham82]

FYI, may want to get out there and do some retesting. 

Hotfix v84:

• Increased Partial Penetrations/Overpens damage and tuned their mechanics in order to have a more realistic effect. HE penetration slightly reduced. As a result, small guns will become more effective, especially at close ranges and HE will be ideal for destroying a ship's superstructure and incapacitating its parts, but not as useful for sinking it.

 

 

[Steeltrap]

On 3/23/2021 at 7:04 PM, cb4 said:

Japan 51 cm/45 (20.1") "A" Type 98 (?) - NavWeaps

The bursting charge of the 20 inch HE shell intended for the A-150 'Super Yamato' would have been 84kg. Not... hundreds of kg.

There are actual data and formulae on how much armor is required to defeat an HE shell.

Okun Resource - Miscellaneous Naval-Armor-Related Formulae - NavWeaps

This formula suggests that a 20 inch nose-fused HE shell could, at most, assuming a point blank impact at 90 degrees at 2300 fps (basically muzzle velocity), blow a 20 inch hole in a 6.8 inch plate of STS homogeneous armor, and that a 8.16 inch plate is the maximum thickness that would be cracked or dented. (Yes, I realize that the armor in the game would be face hardened, but I don't think it makes a huge difference here).

Based on this I would expect a 4.6 inch plate to end up with a ~30 inch hole. As for the 25 inch belt... I wouldn't expect any damage at all. This is generous as we're not talking about point blank, 90 degree impacts, this was an engagement at around 20 km where the shells would be striking much closer to 45 degrees and would been slowed by air drag.

There's a reason that AP was used - HE is just not very effective against heavy armor. If HE shells were able to cause significant, incapacitating damage to battleships without penetrating, battleships would have been built with very different armaments and protection schemes.

In no way should 11 20 inch HE partial penetrations (several of which hit the strongest part of the protection scheme - a protection scheme far stronger than any ever constructed) be able to put a 75,000 ton battleship in serious danger of sinking due to structural damage. Battleship protection schemes were designed to protect propulsion, steering, the main armament, ammunition, and enough reserve buoyancy to keep the ship from sinking from anything short of an AP shell, AP bomb, or torpedo that was actually powerful enough to penetrate.

From HE shells, I would expect damage to the less armored areas, and a superstructure hit to seriously mess up fire control and spotting, but currently in the game, you can *sink* a battleship with HE without ever penetrating its armor. There is no way that is reasonable.

Great points. I've made reference to Okun's work around here before, and even suggested the devs themselves ought to have been familiar with it as part of their background research. There's a reason he rates his own section of NavWeaps. Whether they are or not I've no idea.

Jellicoe himself said he expected only the AP rounds at ~10-12k yards to do the killing damage. HE was expected possibly to do extensive damage to upper works etc etc that might prove disruptive, especially to gunnery spotting and director equipment. This was with the RN using Lyddite, and we all know how well THAT, along with the poor shell quality, worked out.

The troubles is these posts, no matter how well backed up they are with references etc etc, seemingly result in "over-pen". They go in one side of the forum and out the other without appearing to make any serious or lasting impression, especially not on the devs who ultimately are the ones that count.

Not that I'm discouraging it, not at all.

Cheers

[Fenn]

On 3/23/2021 at 8:03 AM, Zuikaku said:

Large HE shells were known for knocking out heavily armoured Panthers and Tigers. The sheer power of explosion and forces of resulting pressure were enough to demolish and displace turrets without penetrating the armour. And incapacitating crew in the process.

I see this commonly bandied about, but there is legitimately no real evidence of this. Big guns can damage, mission kill tanks but straight up kills? Naw.