Final Word on the Effect of Poor Armor Quality? BTS?

[Jeff Heidman]

I would like to get a definitive answer on exactly what it means to say a given vehicles armor quality is some number <100%.

Does an armour quality of 85% (hey Fionn mean:

A. That the actual armor thinckness is equal to 100*.85 = 85mm,

B. That there is some greater chance for a weak point penetration beyong the 15% reduction in armour qualty, or

C. That there is some greater chance for other undesireable effects, like flaking and such, or

D. Some or all of the above.

I know that this ahs come up before, but I could not find a definitive answer to B and C.

Jeff Heidman

[Guest Big Time Software]

As far as I know, only A is true. My understanding of the armor flaws is that they just weren't as capable of stopping AP shot, not that the metal was extra brittle (which would cause B and C most likely).

Steve

[Juardis]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Big Time Software:

As far as I know, only A is true. My understanding of the armor flaws is that they just weren't as capable of stopping AP shot, not that the metal was extra brittle (which would cause B and C most likely).

Steve<HR></BLOCKQUOTE>

Really? That's surprising. I would have definitely said it meant the armor was more brittle, less structurally sound. But if all it does is affect thickness, why include armor quality at all? Unless you do so for the diehard numbers guys who insist that the front turret of the KT is 120mm thick and not 100mm thick .

As an example. The Titanic had flawed steel which, when combined with the cold weather, made it more brittle than it would have been. Hence, it ruptured when it might have dented.

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Jeff Abbott

[Jeff Heidman]

interesting.

Fionn is absolutely convinced that there is a *greatly* increased chance of weak point penetrations and flaking with poor qulaity armor, even to the extent that the reduction in actual armor thickness is not the critical effect.

I would really like to hear something from Charles on this.

Jeff Heidman

[Guest Big Time Software]

Juradis wrote;

<BLOCKQUOTE>quote:</font><HR>Unless you do so for the diehard numbers guys who insist that the front turret of the KT is 120mm thick and not 100mm thick<HR></BLOCKQUOTE>

Bingo The armor ratings need to be consistant. If something was 100mm thick, it should be written out that way EVEN if the effective value is as if it were 85mm.

Jeff, OK, I'll bug Charles for a definitive answer. As I said, I am not totally sure my answer is correct for B and C. Definitely is for A.

Steve

[Jarmo]

Strange, I was sure I had heard an "official" statement the quality

affects the weak point thingy.

Could have been Fionn saying it, though.

[Jeff Heidman]

Thanks Steve.

[Henri]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jarmo:

Strange, I was sure I had heard an "official" statement the quality

affects the weak point thingy.

Could have been Fionn saying it, though.<HR></BLOCKQUOTE>

You bet, there is a rather hot discussion with Fionn on the Usenet war-historical forum about what it means exactly (Fionn doesn't post here any more since he was banned).

Henri

[Priest]

A tragedy really (said very seriously).

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Sir are you sure you want to go to red alert...it would mean changing the bulb

-Priest

[Guest Big Time Software]

OK, in total ignorance of what is going on over on USENET (i.e. I haven't been there in a looooong time) I have the following OFFICIAL information:

Only "A" is correct, as I previously stated.

The "weak point" is basically a small part of a vehicle that is under armored compared to the rest of the surrounding surface. Such as a vision port, MG port, etc. The armor quality is different in that it simulates a round striking the thickest part of the particular surface (i.e. NOT a weak point). If the armor is 100mm thick and at 85%, a round that can only penetrate 90mm of "normal" armor will cause a failure (not sure if "catastrophic failure" is the right term here) of the armor plate and result in a penetration.

Charles used this reasoning:

<BLOCKQUOTE>quote:</font><HR>There could be any of a number of things wrong with the metal. Brittleness is more common than softness here, simply because CM already simulates the armor hardness/softness issue directly. There can also be things like "fault lines" (that's not the precise term) in poorly-made armor. It can also represent poor-quality alloys (e.g. late-war Germany) that just don't resist as well as top-quality plate.<HR></BLOCKQUOTE>

So think of the % armor rating as being a catchall for manufacturing defects. If a round strikes this armor it can result in a penetration. Weak points can happen on ANY vehicle no matter how thick the armor is or its quality. They are meant to be two separate factors.

As for increasing internal flaking, Charles doesn't think that there is a direct reason to increase the chances of this for flawed armor. This would imply that the lower quality armor was more likely to flake if a penetration were defeated, and he simply doesn't have data to support such an assumption.

Steve

[Jeff Heidman]

Thanks Steve, I appreciate you taking the time to fin this out for me.

Fionn is going to be mighty dissapointed!

Jeff Heidman

[Henri]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Heidman:

Fionn is going to be mighty dissapointed!

<HR></BLOCKQUOTE>

I dunno, Jeff;it is not clear to me that this contradicts what Fionn said: he was a bit vague except for saying that the 85% definitely does not refer ONLY to effective armor thickness.He did not reply directly to my question of whether or not the 85% was simply a catchall number that took into account all the effects such as weak spots.

So my understanding of the above is that the 85% IS a catchall number for effective armor thickness -but that also incorporates the other factors that affect penetration, in sum an aggregate measure of probability.And that is what I thought Fionn said in a roundabout way on the Usenet forum.

Henri

[Jeff Heidman]

Well Fionn, rather clearly said that there was a greater chance of a weak point penetration with poor armor. Steve (and Charles) just said that was not true.

He specifically stated that it would be wrong to say exactly what Steve and Charles just did say.

This is not really the place though, since Fionn is not here.

Jeff Heidman

[Jeff Heidman]

I think the important thing to note (and what I wanted to know to begin with) is that case "A" above sums up everything there is to know about lower quality armor. That as far as CM is concerned there is zero difference between 85mm of 100% armor and 100mm of 85% armor.

Effect wise, BTS could have just gone through and multiplied all armor values by their armor quality ratings, and we would not be able to tell the difference.

Jeff Heidman

[Jeff Heidman]

double post

[This message has been edited by Jeff Heidman (edited 01-09-2001).]

[rexford]

Research on the impact of armor flaws resulted in multipliers that convert poor armor to an equivalent thickness of good quality U.S. 240 BHN test plate.

Example:

If a round penetrates 100mm of U.S. good quality test plate and penetrated 120mm of flawed plate at the same angle and velocity, the 120mm plate would have a quality factor of 100/120, or 83%.

Further research showed that the flaw effect was proportional to T/D ratio and influenced by impact angle, where plates that are thick relative to projectile diameter are able to spread impact around better and suffer less from flaws.

If a Panther glacis with medium flaws is hit by 90mm APCBC, the Quality multiplier for 55° hits would be 0.89. Against 122mm APBC, the Quality multiplier for Panther glacis would be 0.85.

When medium flaw Tiger 80mm armor is hit by 75mm rounds, T/D = 1.07, angle is 0° and quality multiplier is 0.98, so 75mm hits do not result in a significant reduction in armor resistance in this case.

Armor flaws is different from weak spots due to weld lines or shot traps.

[Major Tom]

Well, I think that you are right about stating that this isn't the place since Fionn isn't here, but, you probably should not have brought up his name to begin with then.

Finding out something, to find out what it is is one thing. Finding out something just to prove someone else wrong is another.

[Guest Big Time Software]

Jeff wrote:

<BLOCKQUOTE>quote:</font><HR>Effect wise, BTS could have just gone through and multiplied all armor values by their armor quality ratings, and we would not be able to tell the difference.<HR></BLOCKQUOTE>

Correct. Except we would have ever Grog and Grogwannabe telling us our armor values were wrong

Rexford wrote:

<BLOCKQUOTE>quote:</font><HR>Further research showed that the flaw effect was proportional to T/D ratio and influenced by impact angle, where plates that are thick relative to projectile diameter are able to spread impact around better and suffer less from flaws.<HR></BLOCKQUOTE>

Very interesting. It makes quite a bit of sense. I do not think our system takes this into account, rather the poor armor quality rating is rather an abstraction. However, I will pass on your info to Charles for possible future inclusion. Thanks.

Major Tom wrote:

<BLOCKQUOTE>quote:</font><HR>Finding out something, to find out what it is is one thing. Finding out something just to prove someone else wrong is another.<HR></BLOCKQUOTE>

Oh, I don't mind someone coming here to ask something to prove someone else wrong. However, I do think it is totally wrong to carry over a discussion when one side clearly can't enage in it. Jeff, to your credit you did not seek to do this from the start and I don't think Henri meant anything by bringing it up here. But please, let's just drop this aspect of the discussion or I'll feel compelled to lock it up. Anybody interested in the real deal can dial into USENET

Thanks,

Steve

[Treeburst155]

And all this time I've equated weak point penetrations with the armor quality figure. Oh well, ya learn somefink every day.

Treeburst155

[rexford]

See my post on Isigny tests, the 0.85 quality multiplier for Panther glacis does not appear to be warranted against front lower hull nose armor, the cast mantlet or hull side.

Armor flaws on Panther and Tiger II appear to be tied into the large size of the glacis plates and the hardness (above 250 Brinell), which made armor more susceptible to heat treatment errors in Germany than smaller plates or cast.