Nagato/Mutsu armor

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geofflambert
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Nagato/Mutsu armor

Post by geofflambert »

I have a friend who, when he's not working, works on wargames that never will be published. He doesn't care because the process is all the satisfaction he requires. However, he has been disturbed by the performance of Nagato and Mutsu in this game. He says there is a published description of the armor plating on these ships which is inaccurate. He says he's noticed several (three I think) games that follow this incorrect source. I will present to you his essay on this matter along with some evidence. The evidence comes from a work that contains much more including data about all the BB/BCs of the early 20th century. I can scan and submit additional material if needed.

The reason for all this is: #1 is he correct that these ships are underrated by the game? #2 What should be done? Should we develop house rules, in effect, that call for the Japanese player (in PBMs) to alter (through the editor) the armor values of these ships?

Here is his statement:

Over the years I’ve noticed an information problem in various naval games concerning a particular class of warships, namely the I.J.N. Mutsu & Nagato. I don’t know what the source of the error is, but the deck & side armor end up short-changed. According to an excellent German source (Battleships and Battle Cruisers 1905-1970, Siegfried Breyer, trans. Alfred Kurti, Doubleday & Co., 1978), the deck armor on these ships was on the order of 182mm thick (i.e. 32mm more than in the War in the Pacific game), and the side armor was on the order of 375mm thick (i.e. 105mm more than in the game). The result is that in combat these formidable ships tend not to hold up anywhere nearly as well as should be expected.
Part of the problem may be that one of the three armor decks was ignored, and that a 75mm-thick secondary side belt behind the main side belt was ignored. Some might object that a narrow section along the top edge of the main belt is only 200mm thick; but a penetration there by non-plunging fire would hit the lowest armor deck at so extreme an angle that it would have almost nil chance of penetrating into magazine and machinery spaces; moreover a plunging-fire hit there (considering its lower velocity and the relatively extreme angle of incidence on the 200mm belt) would have even less chance of penetrating both the main and secondary belts.


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RE: Nagato/Mutsu armor

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RE: Nagato/Mutsu armor

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RE: Nagato/Mutsu armor

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Alfred
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RE: Nagato/Mutsu armor

Post by Alfred »

You will probably get a better response if you pose the question in the modders sub forum.  Those guys don't always pay full attention to the main forum and usually reserve detailed discussion, if they respond, to that sub forum.
 
I suspect they won't be in favour of a HR to allow just those ships to have the data altered as it would be inconsistent with the rest of the database.  But the editor is always there for players to adjust things as they fit even when it throws everything else out of equilibrium.
 
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RE: Nagato/Mutsu armor

Post by JuanG »

Hi,

In short, while he is not incorrect, there are two issues I see with his calculations. The first is a purely modelling flaw, the second is a 'design' one.

The modelling flaw is the assumption that plates 'stack' linearly - they do not. Two 100mm plates typically equate to ~164mm in ballistic terms, though it depends on the type of shell, impact angles, etc. With larger plates this is typically skewed towards the 'larger' plate.

In the above case, Nagato's deck has an 'effective' thickness of up to 151mm (if one adds up all the thickest points). In that light the stock value of 150mm is not at all too bad. In fact, I personally think it might be a tad overrated, as it would probably make more sense to work out the 'inner' and 'outer' deck effective thicknesses and average them or something, which would net you something in the order of 125-130mm.

For the belt case, the same applies. A purely vertical 300+75 arrangement amounts to something on the order of 330mm, with the plate sloped at 45 degrees like that it starts at 348mm and then varies (decreases and then increases again) with angle of fall of shell.

The 'design' flaw hinges on how exactly one defines 'penetration' in this game - in other words, does the 75mm sloped plate really count towards it, considering the shell is already inside the ship (albeit not the citadel proper). Considering the limitations of the engine in modelling this kind of 'semi-penetration' (same issues applies to CVs with little flight deck but solid hangar deck protection), I am of the opinion that it is best to understate rather than overstate the armour value in these cases.

My two cents.

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Juan
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RE: Nagato/Mutsu armor

Post by Alfred »

geofflambert,
 
You might want to have a look at this thread.
 
http://www.matrixgames.com/forums/tm.asp?m=2905617&mpage=1&key=armor&#2908629
 
Not much discussion around the forum about what was taken into account in determining the armour ratings for stock.  Usually you have to approach the subject from a ballistic, gun penetration perspective.
 
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RE: Nagato/Mutsu armor

Post by Dili »

The question is what the values of Nagato armor in game and if they are inferior.
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RE: Nagato/Mutsu armor

Post by Big B »

If you produced detailed diagrams for every warship - showing the arrangement of all armor, you will see the same pattern with all of them. Nagato is not really singled out.
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RE: Nagato/Mutsu armor

Post by crsutton »

And my question would be does this even take into account the quality of the steel used to build a pre WWI BB in an emerging industrial society, as to say compared to the steel found in a BB built by the US, Germany, or Britain in the late 1930s. I admit, that I have no idea about this but suspect that there must have been a some difference. Are there other variables as well that a two decade advance in ship design would call into effect such as welding vs riveting or structural design refinements (something has to support the armor)? I don't know but am guessing that there is just more than armor thickness that went into the equation.
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RE: Nagato/Mutsu armor

Post by Big B »

To answer your question - I do not "think" the stock game does (I'm fairly certain actually),
But all that can be found HERE

I discovered this resource a number of years ago...
ORIGINAL: crsutton

And my question would be does this even take into account the quality of the steel used to build a pre WWI BB in an emerging industrial society, as to say compared to the steel found in a BB built by the US, Germany, or Britain in the late 1930s. I admit, that I have no idea about this but suspect that there must have been a some difference. Are there other variables as well that a two decade advance in ship design would call into effect such as welding vs riveting or structural design refinements (something has to support the armor)? I don't know but am guessing that there is just more than armor thickness that went into the equation.
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RE: Nagato/Mutsu armor

Post by Symon »

I resoundly support Big B and JuanG. If one wishes to dink with the data, they may, of course, do as they please. If one wants to dink intelligently, then one should understand, at least, the basics of ballistics, projectile/fuse design, and metallurgy. The internet is a poor substitute substitute for intelligence.

FYI: the game engine does not take obliquity into account. For you serious freaks out there, did you note that Nagato's interior armor is at exactly the wrong angle for nominal range shots?

FYI: the game engine does not care about armor quality; 6" is 6", whether tungsten or plastic. Some mods have penetration values that depend on the nominal 'strength' of the armor of an opposing ship. So, all other things being equal (which they were not) a US or Brit 6" will penetrate a lot more Japan armor, that a Japan 6" will penetrate US or Brit armor.

FYI: that is how it is done in the AE database. It's not Squad Leader. One must learn how to do abstractions intelligently.
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RE: Nagato/Mutsu armor

Post by Big B »

Well said John,
ORIGINAL: Symon

{snip}...If one wishes to dink with the data, they may, of course, do as they please. If one wants to dink intelligently, then one should understand, at least, the basics of ballistics, projectile/fuse design, and metallurgy. The internet is a poor substitute substitute for intelligence.
.... It's not Squad Leader. One must learn how to do abstractions intelligently.

To add a little finer point to it all - as John and I (and many others) have found - the deeper you delve into these kind of mechanics (real world physics) ....instead of clarity - the waters can become even murkier, often to a surprising degree.
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RE: Nagato/Mutsu armor

Post by pontiouspilot »

The irony in this discussion is that in RL poor old Mutsu seems to have accidently blown herself up in port, or a suicidal sailor blew them all up.
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RE: Nagato/Mutsu armor

Post by geofflambert »

ORIGINAL: Symon
FYI: the game engine does not take obliquity into account. For you serious freaks out there, did you note that Nagato's interior armor anis at exactly the wrong angle for nominal range shots?

Do you mean that sloped armor behind the armor belt? I was wondering about that myself. It might work well if it were struck by plunging fire but not the nearer range fire where most hits occur. Perhaps they did that to save weight?

By the way everyone, thanks for all this. I'll show it all to him.

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RE: Nagato/Mutsu armor

Post by Nikademus »

Its a turtleback armor deck feature. Often seen in older incremental armor designs. Its meant to enhance protection offered by the primary belt against flatter trajectory shellfire. A shell that manages to penetrate the belt on a descending angle would then have to deal with this sloped armor deck usually causing the shell to detonate or ricochet from the vitals. Bismarck was the last battleship to feature this as part of her armor deck design. The designers were primary concerned with shorter range fights in North Sea or stormy Atlantic conditions. It did help make that ship very hard to sink.
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RE: Nagato/Mutsu armor

Post by wdolson »

A few months ago somebody posted an article on some Yamato class armor the US tested after the war. It was made for one of Yamato's sisters and discarded. It may have been the Shinano.

The piece of armor now sits as a sort of modernist sculpture outside the US Navy arsenal in Washington DC. A US 16 inch shell punched right through it on a test range.

I recall the article said that the USN found the thick armor to be very fragile and easy to penetrate. They also tested some Japanese cruiser armor and it proved to be some of the best armor tested, exceeding British, German, and US armor of the same thickness.

How the armor is made is another factor in its effectiveness. Japanese industry could produce very good armor of medium thickness, but when they went to thicker armor, they couldn't control the crystal size in the metal which made the resulting armor brittle.

I believe I read elsewhere the Germans were particularly good at making thick armor. It was another contributing factor to the ability of the Bismarck to take punishment.

I suspect someone will come up with the article on the Yamato armor. I can't find it at the moment.

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RE: Nagato/Mutsu armor

Post by Symon »

ORIGINAL: wdolson
A few months ago somebody posted an article on some Yamato class armor the US tested after the war. It was made for one of Yamato's sisters and discarded. It may have been the Shinano.
Some data would be nice, my friend. "Some guy posted it" doesn't quite cut it.
I recall the article said that the USN found the thick armor to be very fragile and easy to penetrate.
Once again, some data would be nice. The statement is, of itself, a metallurgical non-sequitor. Fragility is a function of 'inclusions'. If one can make decent medium plate, one can make decent thick plate, so long as one has the requisite thickness on one's rolling mill. Face hardening is another issue, but it has nothing to do with the quality of the base-plate.
They also tested some Japanese cruiser armor and it proved to be some of the best armor tested, exceeding British, German, and US armor of the same thickness.
That is rank, utter, nonsense. Sorry, Bill.
How the armor is made is another factor in its effectiveness. Japanese industry could produce very good armor of medium thickness, but when they went to thicker armor, they couldn't control the crystal size in the metal which made the resulting armor brittle.
Another metallurgical non-sequitor. I have a friend that can make a 6" boule of perfect crucible steel, in his backyard in 16 hours. There is no secret to steel. Face hardening is a bitch, but that has nothing to do with what's underneath.
I believe I read elsewhere the Germans were particularly good at making thick armor. It was another contributing factor to the ability of the Bismarck to take punishment.
Everybody who thinks on these things knows exactly what the parameters of Krupps finest were. Notwithstanding the "everything German is perfect" little kiddles, Krupp armor was pretty much average, and had nothing special to recommend it.

Have a doc with hundreds of contemporary primary sources to support this.
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RE: Nagato/Mutsu armor

Post by Big B »

Agreed, though the Bismark's accumulated punishment before sinking/scuttling (I won't open that one up) had more to do (I believe) with close range(=flat trajectory) hits, than inherent hull strength.
My brother went down to the wreck of the Bismark some years ago with Jim Cameron, and as I recall they found little evidence of damage below the waterline....though the topsides resembled Swiss Cheese....just saying.

B
ORIGINAL: Nikademus

Its a turtleback armor deck feature. Often seen in older incremental armor designs. Its meant to enhance protection offered by the primary belt against flatter trajectory shellfire. A shell that manages to penetrate the belt on a descending angle would then have to deal with this sloped armor deck usually causing the shell to detonate or ricochet from the vitals. Bismarck was the last battleship to feature this as part of her armor deck design. The designers were primary concerned with shorter range fights in North Sea or stormy Atlantic conditions. It did help make that ship very hard to sink.
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RE: Nagato/Mutsu armor

Post by mind_messing »

Have a doc with hundreds of contemporary primary sources to support this.

Let's see them! I, for one, love getting in at the source material influencing game decisions.
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