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Nautical_Metaphor

AP ammo penetration?

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Hi,

contemplating models (rather thanwhile being in actual compbat), how to determine the armor thickness a given shell is able to penetrate?

 

In the Wiki, there is a formula relating HE shell calibre to penetration capability, but not for AP. If I haven't missed it.

http://wiki.wargaming.net/en/Ship:Gunnery_%26_Armor_Penetration#Armor-Piercing

http://wiki.wargaming.net/en/Ship:Ammo

 

I realize the relation has to be fairly complicated because of the whole angling issue, which doesn't apply to HE so it is much  easier to just give that 'divided by 6' or 'divided by 4' rule. No trigonometry required.

 

But there surely has to be a fairly simple formula correlating AP calibre to max armor penetration for un-angled impacts? Just to give you a rough idea?

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No simple formula.

 

I'm not even sure if the penetration formula that WG uses is completely known at this point, but afaik they very try to keep very closely to the real life penetration capabilities of known AP shells. Thus the closest you could get to getting raw epentration numbers would be using the USN empirical formula for armour penetration by Garzke and Dulin.

 

Not quite suited for easy reference.

 

You can also reference this for specific ships' penetration curves. Afaik the user also used the aforementioned formula and cross-referenced it with the known armour penetration values (as they get dropped by the devs in the armada videos).

 

 

 

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[CATS]
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I posted you the links here:

If you do not read the help, it does not work.

 

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[TOXIC]
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1 hour ago, Nautical_Metaphor said:

Hi,

contemplating models (rather thanwhile being in actual compbat), how to determine the armor thickness a given shell is able to penetrate?

 

In the Wiki, there is a formula relating HE shell calibre to penetration capability, but not for AP. If I haven't missed it.

http://wiki.wargaming.net/en/Ship:Gunnery_%26_Armor_Penetration#Armor-Piercing

http://wiki.wargaming.net/en/Ship:Ammo

 

I realize the relation has to be fairly complicated because of the whole angling issue, which doesn't apply to HE so it is much  easier to just give that 'divided by 6' or 'divided by 4' rule. No trigonometry required.

 

But there surely has to be a fairly simple formula correlating AP calibre to max armor penetration for un-angled impacts? Just to give you a rough idea?

HE penetration is simple. A shell hits an armor, there's a penetration value specific for the shell (depending on caliber, nation and IFHE skill) and this value is compared to armor thickness.

 

Not so with AP. AP shells don't have a "penetration" value because they actually rely on their kinetic energy to punch through the armor. And shells don't travel at constant speed. And when they finally hit the target, there are all the angle considerations... Getting the maximum possible penetration value against flat armor at point-blank range would be a pretty useless info to have - and one that would actually serve as misinformation rather than information (people would see the awesome pen values of some guns and then get surprised by never seeing anything in the same dimension of "promised" performation in actual in-game performance). The best we could have would probably be some numbers for 2/5/10/15km - but these would be deceptive too since shells at longer ranges come at an angle (from above) even at perfectly broadside targets.

 

Basically, the penetration model for AP is much, MUCH more complicated and can't really be derived from gun stats available in port. The one exception is penetration of targets at autobounce angle - you KNOW you won't penetrate unless you overmatch and overmatch mechanics are simply a function of caliber and armor thickness (not unlike HE penetration).

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[GRKEN]
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There's no simple formula or rules.

While it's based on real world things like shell's initial velocity, weight, drag etc that's then modified by "Krupp" value which is coefficient WG uses to adjust things.

Good example is 130mm AP of Soviet DDs vs AP of USN 127mm/38 AA catapult/mortar.

Soviet AP has IIRC 60% higher muzzle energy and superior ballistics (long heavy shell with high sectional density) but its Krupp value is so bad that up to 7km their penetration is basically same.

 

And of course you need to know what kind armor targeted ship has.

Aimed to wrong spot shells can shatter or overpen instead of doing lots of damage.

And even generalizing per ship class doesn't work:

Against all or nothing armor scheme battleships DD AP can do lots of damage.

While "tapered armor"/medium armor including battleships would just shatter those shells.

 

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[ADRIA]
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3 hours ago, Nautical_Metaphor said:

But how about thumb rules?

The only one of those is the overmatch - caliber divided by 14.3 and then always rounded down - if the armour you hit is at that thickness or lower you overmatch it. Somehow you still can manage to bounce tho, like high caliber AP on DDs. No idea how, but it's a (pretty rare) thing.

 

Everything else with AP is far more complicated calculations

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