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Old 06-18-2019, 09:08 PM   #51
Icelander
 
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Default Re: Modern Body Armor

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I wasn't talking about ceramic plates, those are inherently brittle (though there's some stuff that can be done with crack propagation). However, plastic level III plate seems pretty comparable to metal.
Well, it's true that plastics are much less brittle than ceramic composites and seem to be much better now than a decade ago. I don't really know whether they'll keep improving or whether there are some physical limits in sight, however.

Steel plates are impractical for Level IV body armor for humans because they weigh too much. Whereas HDPE plates don't (at least currently) work for Level IV body armor because, in GURPS terms, the DR per inch is too low. Both can work for Level III, but a surprisingly high number of HDPE plates that pass Level III testing are vulnerable to certain commonly used military 5.56x45mm rounds (not actually part of Level III standards), at least at high velocities.

From what I can tell, reading reviews, research and random Internet things, some of the most promising armor plates are hybrid designs. HDPE is light and durable, but not strong enough. Ceramic is light enough and strong enough, but too brittle. Steel is strong enough and durable enough, but too heavy.

That being said, in a world with supernatural threats, steel is a lot more attractive than in the real world. For one thing, fae hate and fear it, lose their balance and senses around it and have trouble perceiving the wearer clearly, let alone affect him with their glamour. It also provides some minimal protection from other magic, giving at least a -1 to attempts to affect the wearer. Granted, steel armor is not ideal for anyone wanting to be enhanced with magic, but while steel might give a slight penalty to magic, ceramic composites or HDPE are going to interfere worse with any spellcasting.

For another, nothing 1" thick will ever make for remotely concealable body armor, but Level III steel plates are only about a fifth of that. 5 mm is within the range of historical breastplates, which can be concealed under heavy clothing.

And, of course, ordinary humans don't tend to have ST 20, but chevals with friendly spirits or ritual magicians with the right charms can be stronger than any mortal for a night of slaying monsters. Not to mention monsters who might want armor, like vampire enforcers, revenant special operators or embodied warrior spirits.

I figure Monster Hunters with no magic of their own favor ballistic polymer soft underlayers and HDPE plates, along with every modern gadget and accessory they can get, for protection from hostile magic, while the Monster Hunters who fight fire with fire and magic with magic, they are going to be wearing steel armor and using old-school shotguns, lever-action rifles and revolvers.
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Last edited by Icelander; 06-19-2019 at 04:01 PM.
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Old 06-18-2019, 10:47 PM   #52
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Default Re: Modern Body Armor

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Whereas HDPE plates don't (at least currently) work for Level IV body armor because, in GURPS terms, the DR per inch is too low.
Actually, it's probably more accurate to say that Hardened is available for ceramic and not for other armor types.
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Old 06-18-2019, 11:54 PM   #53
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Default Re: Modern Body Armor

The Ablativeness *is that a word ?* of Ceramic plates is fairly overstated, you shouldnt absorb round after round, but it can stand up to multiple impacts fairly well

https://www.youtube.com/watch?v=oG15mCbj74w

while a Steel plate can take hundreds of rounds, because as the guy mentions, they are basicly a Steel Target, usually with some kind of liner or somesuch on them
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Old 06-19-2019, 02:18 PM   #54
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Default Re: Modern Body Armor

In the case of Gorilla Glass, a surface treatment helps keeps cracks from propagating through the material. I wonder if there is a similar process for ceramic?
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Old 06-19-2019, 03:13 PM   #55
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In the case of Gorilla Glass, a surface treatment helps keeps cracks from propagating through the material. I wonder if there is a similar process for ceramic?
There are certainly things you can do to limit crack propagation. The problem is that they might not be compatible with your primary goal of stopping bullets.
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Old 06-19-2019, 06:55 PM   #56
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Default Re: Modern Body Armor

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Actually, it's probably more accurate to say that Hardened is available for ceramic and not for other armor types.
That's one way, but I'm not sure that Level IV armor is well represented by giving it DR 25 and one level of Hardened. After all, just because it stops AP rounds in GURPS terms doesn't mean that it would stop APHC.
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Old 06-19-2019, 08:15 PM   #57
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Default Re: Modern Body Armor

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That's one way, but I'm not sure that Level IV armor is well represented by giving it DR 25 and one level of Hardened. After all, just because it stops AP rounds in GURPS terms doesn't mean that it would stop APHC.
Well, that might be an issue of having sufficient DR, but for kinetic penetrators there really is a correlation between 'hardened' and material hardness, and the common ceramic armor materials (boron carbide, corundum, silicon carbide) are all harder than metallic tungsten and at least as hard as tungsten carbide.
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Old 06-20-2019, 04:49 PM   #58
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Well, that might be an issue of having sufficient DR, but for kinetic penetrators there really is a correlation between 'hardened' and material hardness, and the common ceramic armor materials (boron carbide, corundum, silicon carbide) are all harder than metallic tungsten and at least as hard as tungsten carbide.
I think the issue is that no body armor I am aware of can fully neutralize the (2) Armor Divisor of APHC rounds, but is otherwise no more protective than NIJ Level III armor. There might be ceramic composites that, in GURPS terms, reduce the effectiveness of APHC and stop hardened steel AP rounds of similar weight and velocity as ball ammunition it is rated for, but that's more complexity than the RAW.

In realistic terms Hardened doesn't exist, largely because GURPS gives Armor Divisors to various different penetrators and real armor which neutralizes all of these at the same time (without having higher DR) doesn't exist.

Various high hardness armor, like boron carbide, might justifiably have half a level or so of Hardened against high hardness penetrators, which would in game terms neutralize AP (i.e. let it penetrate as ball ammo) and reduce APHC to the penetration values for AP.
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Old 08-24-2023, 09:25 AM   #59
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In realistic terms Hardened doesn't exist, largely because GURPS gives Armor Divisors to various different penetrators and real armor which neutralizes all of these at the same time (without having higher DR) doesn't exist.

Various high hardness armor, like boron carbide, might justifiably have half a level or so of Hardened against high hardness penetrators, which would in game terms neutralize AP (i.e. let it penetrate as ball ammo) and reduce APHC to the penetration values for AP.
Fascinating thread, Icelander and team!

Does this mean that AP rounds shouldn't actually have Armor Divisors in the real world? Should we just step-up AP damage to make up for it? Does GURPS maybe need an (1.5) Armor Divisor step to better fit real-world data?

(Sorry for resurrecting an old thread, first-time poster here.)
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Old 08-24-2023, 10:25 AM   #60
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Default Re: Modern Body Armor

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Fascinating thread, Icelander and team!

Does this mean that AP rounds shouldn't actually have Armor Divisors in the real world? Should we just step-up AP damage to make up for it? Does GURPS maybe need an (1.5) Armor Divisor step to better fit real-world data?

(Sorry for resurrecting an old thread, first-time poster here.)
General-purpose AP and Hardened probably aren't realistic, but limited versions are. That is, some weapons will readily penetrate certain types of armor materials but not other types. From my understanding, how it works out is a bit complicated. Also, limited Hardened isn't a thing in GURPS, so it's typically done as "increased DR vs certain threats" - like how I believe laminated armor gets either a x2 or x3 to its DR against shaped-charges. Personally, I'm generally comfortable with just simplifying things down to the default general-purpose AP and Hardened that's in GURPS.

A (1.5) AD would probably be useful for smoothing out the progression, as might a (7) AD (it currently goes (2), (3), (5), (10)), but GURPS is definitely not a fan of dividing by 1.5 (or multiplying by 0.7, which is basically the same -1 SSR as dividing by 1.5) or of dividing by 7, so those two tend to get skipped a lot. There's also the fact that (1.5) for +50% is difficult to justify - absent other Enhancements, you can get x1.5 to outright damage (which isn't susceptible to Hardened) for the same cost as a +50% Enhancement. Making Armor Divisor +25% and +1 SSR per level might be alright, making it basically be the same "extra damage at half-price for being susceptible to Hardened" as the first level for the whole progression. But then again, half price for being susceptible to Hardened is probably undercharging; if you consider the (10) level to be the most appropriately-priced at +200%, that's +33.33% per +1 SSR, which I'd probably round down to +30% per +1 (making (10) cost +180% instead of the +200% of the default or the +150% of +25% per +1 SSR). Whatever you opt to charge for Armor Divisor, Hardened should be around -2 SSR to price (currently that's +50% per level for AD, +20% per level for Hardened; if you drop it to +25% for AP, Hardened should probably be +10%, while if you drop it to +30%, Hardened should probably be +15%).
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