What is better armor? 400mm or 4x100mm?

[fnord_disc]

I tried picking a less scientific title this time in the hopes that it attracts more readers ;-)

 

Introduction

The discussion about Amagi's armor on Reddit has shown me that much education still needs to be done on this subject. In particular, I saw an argument being made that Amagi has 250mm of belt armor and 100mm of angled citadel armor behind it. The argument then, presumably, insists that this is roughly equivalent to Yamato's 400mm belt under the assumption that angled 100 ~= 150mm and so 250mm+150mm=400mm.

This view is fallacious.

However, please note that this does not concern itself with the size of the hit box, which is clearly very small on Amagi.

Where the math comes from

Penetration has been reverse-engineered a while ago and iChase and I also reverse-engineered speed loss after penetration of armor when he worked on citadel overpenetrations. At the time, analysis of citadel overpenetrations was the only goal, but this also lets us judge whether salami armor is inferior, superior, or comparable to a heavy concentration of armor on the broadside.

What I have done in a rather quick and ghetto fashion here is simulate a Yamato shell with 500mm of penetration at the first armor plate penetrating a series of plates. The sum of the plates is always 400mm, but they are split into 1-4 individual layers.

The Plot

http://i.imgur.com/g2rMDFz.png

The difference is very striking. Yamato's 500mm penetration shell retains 95mm penetration behind the 400mm plate. It retains more than 450mm of penetration after 4x100mm plates.

tl;dr

Splitting armor into several layers is very bad and greatly compromises the usefulness of armor. Amagi's 250+150 is more equivalent to a 300mm belt than to 400mm.

[Aotearas]

4x100mm on the basis that even just air in between the plates bleeds energy amounting to a greater sum of protection than just the plating itself, nevermind the whole thing about setting off fuzes to detonate prematurely.

[ScratxNeko]

4x100mm on the basis that even just air in between the plates bleeds energy amounting to a greater sum of protection than just the plating itself, nevermind the whole thing about setting off fuzes to detonate prematurely.

 

That's not how it works, though. Penetrating armor is more of a factor of local resistance at the impact point. A thicker plate is MUCH more resistant to penetration than two plates, air-gapped, that together match the same thickness.

[fnord_disc]

4x100mm on the basis that even just air in between the plates bleeds energy amounting to a greater sum of protection than just the plating itself, nevermind the whole thing about setting off fuzes to detonate prematurely.

 

First of all, I simulate the game and not reality. This is not the navweaps forum.

 

Second, laminated armor is simply inferior in thickness to single-layer armor in reality. Only fringe effects make laminated armor useful is certain rare cases.

 

I refer you to Nathan Okun:

 

http://www.navweaps.com/index_nathan/Multi-plate_discussion.pdf

[Fino_93]

In real Life 1x400 would be better as scratxneko has explains.

 

In the game 1x400 is better cause if i manage to penetrate 1 or more of the 1x100 layers my Shell would detonate insides the ship, i could miss the citadel but i would do a penetrating damage that could be prevented by 1X400.

[Aotearas]

 

First of all, I simulate the game and not reality. This is not the navweaps forum.

 

Second, laminated armor is simply inferior in thickness to single-layer armor in reality. Only fringe effects make laminated armor useful is certain rare cases.

 

I refer you to Nathan Okun:

 

http://www.navweaps.com/index_nathan/Multi-plate_discussion.pdf

 

Ah, I misunderstood then.

 

And nice referral, I shall read that when I got some time, thanks

[Panocek]

Speaking of Amagi armor, I'm curious if inner 250mm plate counts for protection, or it counts as one with outer armor belt?

[Aviadvigatel]

I would think 4x100... Bismarck and Tirpitz is proof enough i would say.. They were so difficult  to destroy because of a inner armor plating making it really hard to penetrate... It is a documentary on Youtube about exactly that,where they explain how it worked.. I cant remember exactly what they said,but it was like Aotearas said,that the Air also was in on stopping the shell... King George V and Rodney fired over 670 14 and 16 inch shells,and Bismarck still had her flags up remaining a fleet..

[BuccaneerBill]

I would think 4x100... Bismarck and Tirpitz is proof enough i would say.. They were so difficult  to destroy because of a inner armor plating making it really hard to penetrate... It is a documentary on Youtube about exactly that,where they explain how it worked.. I cant remember exactly what they said,but it was like Aotearas said,that the Air also was in on stopping the shell... King George V and Rodney fired over 670 14 and 16 inch shells,and Bismarck still had her flags up remaining a fleet..

 

 

Bismarck had a 110mm highly angled slab of armour behind the 320mm main belt, that's why they were hard to citadel up close. But normal battles are at range where plunging fire  which partially negates that layout and also allows underwater shots, where Bismarck had little protection..  Like POW did to Bismarck during the Denmark Strait,underwater shot, hitting underneath the armour and flooding machinery. Bismarck's armour is only really good at close range like in the final battle, but still most of the shots hit the superstructure and guns and you don't really sink ships like that. But you do turn them into burning hulks.

 

Bismarck's flags were only probably up because their was no one left alive above the armoured deck to take them down?

[Ictogan]

Speaking of Amagi armor, I'm curious if inner 250mm plate counts for protection, or it counts as one with outer armor belt?

 

 

You are just looking at the armor belt from the inside. Unlike e.g. the Bismarck there's no second armor plate at that location, you're literally looking through a hole at the inside of the same plate you can see on the outside. At least that applies to some other ships and I believe it applies to Amagi as well.

[philjd]

I would think 4x100... Bismarck and Tirpitz is proof enough i would say.. They were so difficult  to destroy because of a inner armor plating making it really hard to penetrate... It is a documentary on Youtube about exactly that,where they explain how it worked.. I cant remember exactly what they said,but it was like Aotearas said,that the Air also was in on stopping the shell... King George V and Rodney fired over 670 14 and 16 inch shells,and Bismarck still had her flags up remaining a fleet..

 

There is a difference between destroying and rendering ineffective - the Biz was rendered 'hors de combat' long before she scuttled/torped into being a 1 way submarine.

A number of definitions:-

Hard Kill - sunk (destroyed)

Soft Kill - rendered ineffective and harmless

Mission Kill - damaged enough to prevent the ship from performing it's mission.

 

In Biz's case, the PoW hit did a mission kill (forcing a return to harbour and no raiding). During the final battle she was soft killed by KGV/Rodney., Then sunk (by self or torps, doesn't really matter which).

 

OT -  Navweapons is a superb resource (so can Warships1 be if the right people join the thread), lots of knowlege. Just hope that WG used something similar in the mechanics.

[Panocek]

 

You are just looking at the armor belt from the inside. Unlike e.g. the Bismarck there's no second armor plate at that location, you're literally looking through a hole at the inside of the same plate you can see on the outside. At least that applies to some other ships and I believe it applies to Amagi as well.

 

When I browsed Amagi it looked more like inner 250mm plate to me. That or don't do science when tired and after mead.

[Historynerd]

That may be somewhat worrying, if I understood this correctly, and I am not making mistakes (I am making a supposition that this mechanic always applies, and there is no game-wise application of the IRL phenomenon of APC shells decapping).

 

(Sorry if I always drag the discussion towards these topics, but I believe it might be somewhat relevant.)

 

This basically causes the Littorio (the assured Tier VIII battleship of the future Italian tech tree) to have one of its biggest advantages severely curtailed, as the non-application of the decapping effect that its vertical armour layout was supposed to cause make its layered concept nothing but a hindrance.

f I did not misunderstood something, the resulting 70 + 280 mm layered armor will be relatively weaker than a uniform slab of 350 mm, thus making the Littorio less than impressive in protection (and overall reflecting badly on its standing along with the other Tier VIIIs, as its powerful if  guns and its protection balanced the long reload times and the deficiences of AA).

 

Of course, this is very much in the far future, so there's plenty of time to look at this issue and find a way, but if there is no way to implement the effects of the "decapping plate" concept (which however would be a major headache), I believe there is no other way, for the sake of balance, than cheat a bit and give the Littorio a revised armor scheme accounting for a uniform 350 mm plate, to redress the weakness that its IRL layered layout may create.

[Exocet6951]

 

When I browsed Amagi it looked more like inner 250mm plate to me. That or don't do science when tired and after mead.

 

It's poorly rendered, because the way it's shown, there are both an inside and outside plate, both being 250mm

 

 

I think it's just simplifying things, where the outside is 250mm, and the inside is a small splinter shield or something.

They didn't take the time to modify it, because it would be a lot of work for something which almost no one sees.

[Ictogan]

 

When I browsed Amagi it looked more like inner 250mm plate to me. That or don't do science when tired and after mead.

 

From looking at ships where there are definitely further inner angled plates, like german BBs, it seems that the armor viewer always calls those "deck" and not "armor belt". Note that the Amagi does have an angled inner plate at exactly the location where an inner plate would be found though, it's just part of the citadel armor.

[Ictogan]

That may be somewhat worrying, if I understood this correctly, and I am not making mistakes (I am making a supposition that this mechanic always applies, and there is no game-wise application of the IRL phenomenon of APC shells decapping).

 

(Sorry if I always drag the discussion towards these topics, but I believe it might be somewhat relevant.)

 

This basically causes the Littorio (the assured Tier VIII battleship of the future Italian tech tree) to have one of its biggest advantages severely curtailed, as the non-application of the decapping effect that its vertical armour layout was supposed to cause make its layered concept nothing but a hindrance.

f I did not misunderstood something, the resulting 70 + 280 mm layered armor will be relatively weaker than a uniform slab of 350 mm, thus making the Littorio less than impressive in protection (and overall reflecting badly on its standing along with the other Tier VIIIs, as its powerful if  guns and its protection balanced the long reload times and the deficiences of AA).

 

Of course, this is very much in the far future, so there's plenty of time to look at this issue and find a way, but if there is no way to implement the effects of the "decapping plate" concept (which however would be a major headache), I believe there is no other way, for the sake of balance, than cheat a bit and give the Littorio a revised armor scheme accounting for a uniform 350 mm plate, to redress the weakness that its IRL layered layout may create.

 

They didn't combine the decapping plate and main belt for Iowa, which also makes it a weakness for her because the decapping plate can very easily be penned by small caliber AP. The main belt on it will protect against citadels, but not regular pens.

[Historynerd]

They didn't combine the decapping plate and main belt for Iowa, which also makes it a weakness for her because the decapping plate can very easily be penned by small caliber AP. The main belt on it will protect against citadels, but not regular pens.

 

I see, but on Iowa the decapping plate concept was not brought to the extreme as in the Littorio. Plus, the Iowa is fast, her AA suite seems good, so she doesn't need an edge in protection as much as the Littorio, I believe.

[fnord_disc]

That may be somewhat worrying, if I understood this correctly, and I am not making mistakes (I am making a supposition that this mechanic always applies, and there is no game-wise application of the IRL phenomenon of APC shells decapping).

 

Correct. There is no APC decapping mechanic.

 

 

This basically causes the Littorio (the assured Tier VIII battleship of the future Italian tech tree) to have one of its biggest advantages severely curtailed, as the non-application of the decapping effect that its vertical armour layout was supposed to cause make its layered concept nothing but a hindrance.

f I did not misunderstood something, the resulting 70 + 280 mm layered armor will be relatively weaker than a uniform slab of 350 mm, thus making the Littorio less than impressive in protection (and overall reflecting badly on its standing along with the other Tier VIIIs, as its powerful if  guns and its protection balanced the long reload times and the deficiences of AA).

 

The space between those two armor layers on Littorio is very small - Lesta might not model it as separate plates, but as a single 350mm plate. In fact, even Breyer's book gives the belt as 350mm. According to my books, the gap between the two armor layers was only 25cm and to my knowledge such small spaces are not modelled in the game.

 

I would assume that Littorio will receive a uniform 350mm belt.

[Historynerd]

Correct. There is no APC decapping mechanic.

 

The space between those two armor layers on Littorio is very small - Lesta might not model it as separate plates, but as a single 350mm plate. In fact, even Breyer's book gives the belt as 350mm. According to my books, the gap between the two armor layers was only 25cm and to my knowledge such small spaces are not modelled in the game.

 

I would assume that Littorio will receive a uniform 350mm belt.

 

Yes, the space between the two plates was only 250 mm, although this was reputed enough for the decapping effect to take place, at least for 381 mm shells at the expected combat ranges.

(And, all due respect, but Mr. Breyer's statement makes my eyebrows rise a bit)

 

In any case, it's alright. As long as WG balances out the ship, no issue. I know this was always going to be very difficult, if not impossible, to simulate.

[fnord_disc]

 (And, all due respect, but Mr. Breyer's statement makes my eyebrows rise a bit)

 

Breyer is known to have been a little lazy when it comes to the armor layouts.

[Bellegar]

Very interesting thread/discussion. But can some one explain to me what decapping armor and effect are and how it works?

[piritskenyer]

This is a recurring one!

 

As far as I know laminated armour can only work well if the individual plates are at least half as thick as the attacking shell's calibre. Also, a lot depnds on hardnesses and metallurgic proprerties, which puts the whole argument on a level so technical that I'm not even going to attempt to have a go at it (well, as long as I'm at work, that's for sure).

[piritskenyer]

 

There is a difference between destroying and rendering ineffective - the Biz was rendered 'hors de combat' long before she scuttled/torped into being a 1 way submarine.

A number of definitions:-

Hard Kill - sunk (destroyed)

Soft Kill - rendered ineffective and harmless

Mission Kill - damaged enough to prevent the ship from performing it's mission.

 

In Biz's case, the PoW hit did a mission kill (forcing a return to harbour and no raiding). During the final battle she was soft killed by KGV/Rodney., Then sunk (by self or torps, doesn't really matter which).

 

OT -  Navweapons is a superb resource (so can Warships1 be if the right people join the thread), lots of knowlege. Just hope that WG used something similar in the mechanics.

 

Ahem.

 

Now I may be wrong, but the kill categories are as follows:

 

M-kill (Mobility kill - no engine and/or steering)

F-kill (Firepower kill - no workable armament)

K-kill (Catastrophic kill - damage that renders the vehicle beyond recoverable and repairable status)

 

All of which are a type of mission kill, but not all mission kills fall into these categories.

 

Example for an

• M-kill: Hit that Bismarck's rudder sustained making her able to sail in circles
• F-kill: Hits sustained by Bismarck making her FC and actual armament inoperable
• K-kill: The hit HMS Hood sustained to her magazines, blowing her up

All of these are mission kills because they rendered the ships sustaining them unable to perform their missions as intended. A mission kill that falls under none of these would be beaching (although that can be considered an M-kill)

 

[SparvieroVV]

 

Yes, the space between the two plates was only 250 mm, although this was reputed enough for the decapping effect to take place, at least for 381 mm shells at the expected combat ranges.

(And, all due respect, but Mr. Breyer's statement makes my eyebrows rise a bit)

 

In any case, it's alright. As long as WG balances out the ship, no issue. I know this was always going to be very difficult, if not impossible, to simulate.

 

The space was the minimum considered necessary.  The original design called for a larger space however concerns over battle damage stripping out the decapping plate or space becoming voided and vulnerable to flooding saw the minimum calculated space used. Hopefully WG gives the Abruzzi and Littorios a little leeway to make up for the loss of these plates. Okun states a minimum of 100mm is necessary to decap a 381mm shell. Afaik the Italian shells where designed to be a bit more pointed to defeat face hardened armor and be a bit harder to decap. So the 250mm gap should be a little overengineered.

 

How does WG treat Iowa's 1.5" STS plate? From the armor viewer it seems to just treat it as an outer portion of the armor system.

[mr3awsome]

During the final battle she was soft killed by KGV/Rodney., Then sunk (by self or torps, doesn't really matter which).

Its a hard kill. By the time Bismarck was torpedoed and the scuttling charges went off the ship was already going under. It only sped up the inevitable.