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Old 05-07-2017, 09:06 AM   #11
vitruvian
 
Join Date: Aug 2004
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Just set some kind of threshold that looks good for total momentum of the impacting projectile (e.g., a cannonball has substantially more momentum, if not energy, than a much higher velocity rifle round). Above this threshold, treat it like impact damage from collisions and falls, i.e., even rigid armor lets blunt trauma through.
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Old 05-07-2017, 10:52 AM   #12
Varyon
 
Join Date: Jun 2013
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

First off, all piercing attacks should have something like a crushing component to them, for things like knockback, blunt trauma, etc. For firearms, this is somewhere around 1/3rd of the actual damage (this seems to scale slowly with projectile size - Pi is around 1/3, Pi+ is around 1/2.5, Pi++ is around 1/2, at least on the lower end, as GURPS doesn't have a Pi+++ or larger category). For rigid armor, what happens with a non-penetrating, non-deforming (no dents, cracks, etc) hit is that you essentially have the impactor and plate become a single entity with the same momentum as before, pushing into the target. With a breastplate, this is a huge area, so you end up with no real injury. With a trauma plate, it may be smaller, so with that same amount of energy focused into a smaller area, you can get into some actual wounding, although that's not very likely - the energy needed to harm the wearer is usually more than enough to cause deformation of the plate.

With deformation, the easiest way to think of it is as a dent - all that energy gets focused into a much smaller area, so there's more potential for wounding. Actually deforming the plate burns up a decent amount of energy, however, which complicates matters. This is where you see the potential for broken ribs and the like.

My planned Armor and Wounding Overhaul is intended to have this as an integral part of it, but that's nowhere near ready to post, and changes things a lot more than just "Bullets can cause blunt trauma." For the latter, flexible armor should result in 1 point of Blunt Trauma for every 20 points of Pi-, 15 points of Pi, 12 points of Pi+, or 10 points of Pi++ (cannons and the like already typically do crushing). Ceramic trauma plates should probably count as flexible, as they deform (shatter) fairly readily, but having them downgrade the piercing class (Pi+ becomes Pi) for purposes of Blunt Trauma may be appropriate (to represent the energy absorbed by deformation). Truly rigid armor - including steel trauma plates - result in no injury if piercing damage does not exceed something like half DR. If it does exceed half DR, the armor suffers some degree of deformation, which doesn't impact its ability to continue functioning but can transfer some injury to the target - use the above progression, but downgrade the piercing class by two steps (Pi+ becomes Pi-). For armor with different performance against piercing damage rather than crushing, like Kevlar, you may wish to convert damage to crushing to see if actual damage gets through, rather than just Blunt Trauma. To convert, divide Pi- damage by 4, Pi by 3, Pi+ by 2.5, and Pi++ by 2. Note you may wish to do this for very light targets as well, to determine how much knockback your orichalcum-armored pixie suffers when he takes a blunderbuss to the chest.
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Old 05-07-2017, 03:42 PM   #13
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Quote:
Originally Posted by Tomsdad View Post
Actually it is being reported as a problem
BABT is actually the armor's DR being exceeded, just not by very much.
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Old 05-07-2017, 03:51 PM   #14
Ulzgoroth
 
Join Date: Jul 2008
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Quote:
Originally Posted by Anthony View Post
BABT is actually the armor's DR being exceeded, just not by very much.
It's not piercing damage behind the armor, though, or they wouldn't be calling it blunt trauma.
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Old 05-07-2017, 04:28 PM   #15
Anthony
 
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Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

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Originally Posted by Ulzgoroth View Post
It's not piercing damage behind the armor, though, or they wouldn't be calling it blunt trauma.
Sure, but that's an issue of mechanics. BABT for rigid armor doesn't occur if the armor significantly outclasses the attack, it's a feature of partial failure. You could do something like treat half the armor's DR as flexible.
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Old 05-07-2017, 07:30 PM   #16
Fred Brackin
 
Join Date: Aug 2007
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Quote:
Originally Posted by Anthony View Post
BABT is actually the armor's DR being exceeded, just not by very much.
By strict reading of the rules I believe someone with DR23 (Rigid) from a trauma plate and DR 12(Flexible) from the associated vest gets blunt trauma (Gurps style) on anything over the 23 but under the total of 35.
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Old 05-08-2017, 01:28 AM   #17
Tomsdad
 
Join Date: Jan 2010
Location: Brighton
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Quote:
Originally Posted by Anthony View Post
BABT is actually the armor's DR being exceeded, just not by very much.
EDIT: Actually it seems to be based on absolute the energy of the round in question as well not just how close it gets to the DR. Obviously as that goes up it takes higher and higher rated plates to see the effect at all! Weaker plates being penetrated so no BABT to see.

Quote:
Originally Posted by Ulzgoroth View Post
It's not piercing damage behind the armor, though, or they wouldn't be calling it blunt trauma.
Quite

Quote:
Originally Posted by Anthony View Post
Sure, but that's an issue of mechanics. BABT for rigid armor doesn't occur if the armor significantly outclasses the attack,

Only in trauma of TL8 body armour, "outclassing" is matter of DR and actual weapon damage relative to each other, and the blunt trauma rules will give you that. Because at TL8 you ballistic plate will either be facing:

lower energy rounds and easily stopping them (i.e outclassing them) and they will do little or no blunt trauma because they're damage is low

Higher energy rounds and stopping them (but not outclassing them by as much) and since the round will be doing higher damage you get more chance of more blunt trauma.

Or failing all together and blunt trauma is moot




Quote:
Originally Posted by Anthony View Post
it's a feature of partial failure. You could do something like treat half the armor's DR as flexible.
I take you point about partial failure (as in full success is no negative effect from being hit not just stopping the round penetrating*). But if you did the above you pretty much limit blunt trauma to 1 point in TL8 plates. Which kind of goes against the point the linked article was making that it get worse the more powerful the round is. But that said it's going to depend on what your view of 1 or 2 points of blunt trauma is, at this end of the spectrum the system doesn't give much granularity.


*but in RL I'm not sure that's how the industry and it customers rate it, from what I've read it seems to be more about penetration or not (for obvious reasons).

Quote:
Originally Posted by Fred Brackin View Post
By strict reading of the rules I believe someone with DR23 (Rigid) from a trauma plate and DR 12(Flexible) from the associated vest gets blunt trauma (Gurps style) on anything over the 23 but under the total of 35.
I agree that is a reasonable reading, but again it will in effect limit blunt trauma to only ever being 1 point in TL8 body armours.

However that said even if you do limit it to 1 point it would seem to cover most of levels do injury the article seems to describe (unusual events can be covered by critical hit effects)


I guess it's going to come down to what you consider 1 point of blunt trauma injury to be. Or more accurately what we view the damage referenced in the article to be in GURPS terms. I quite like the idea of allowing blunt trauma to the vitals getting the knock down check from MA for instance.

Last edited by Tomsdad; 05-08-2017 at 07:35 AM.
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Old 05-08-2017, 02:59 AM   #18
Tomsdad
 
Join Date: Jan 2010
Location: Brighton
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Thinking about that last point, I'm beginning to think that worrying about weather it's 1, 2 or 3 points of blunt trauma isn't really worthwhile. Instead just allowing blunt trauma to count as cr for knock down tests. That way BABT isn't really a problem when you are hit in most places, but can potentially have an effect if you get hit in the vitals or skull where you have to make knockdown test. This would seem to match the article posted earlier.

Accordingly I like Anthony's idea of splitting plates to count as 1st half rigid, 2nd half counts as flexible for calculating blunt trauma.

That way low energy bullets that likely won't do more than half DR damage won't threaten BABT, more energetic ones that go past the halfway threshold might if they go past by enough.


It's a bit threshold-y, but i think it could work

Last edited by Tomsdad; 05-08-2017 at 07:13 AM.
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Old 05-08-2017, 03:31 AM   #19
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Quote:
Originally Posted by Tomsdad View Post
lower energy rounds and easily stopping them (i.e outclassing them) and they will do little or no blunt trauma because they're damage is low
5.56mm bullets against level IV armor should do 0, not 1. Against level III armor, doing a point is reasonable (and they'll go right through level IIIa).
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Old 05-08-2017, 03:36 AM   #20
Tomsdad
 
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Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Quote:
Originally Posted by Anthony View Post
5.56mm bullets against level IV armor should do 0, not 1. Against level III armor, doing a point is reasonable (and they'll go right through level IIIa).
That seems very precise in terms of RL conversion to GURPS, what are you basing that on?

(but also see my post directly above yours here, and the general point made about what does 1 point of damage actually mean here in RL terms)

Oh and thinking about skulls and non penetrating trauma I realise we've discussed this before as part of the usual weapons vs. DR threads here

Last edited by Tomsdad; 05-08-2017 at 05:48 AM.
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