Armor, Hit locations, and math Options

[Crusher Bob]

Since I don't think it's come up on the new boards, and I didn't want to get involved on the firearms thread, here's some stuff about armor, hit locations and other interesting bits:

First question? If we wanted to make a random hit table, what percentages should we use for each location of the body?

Surveillance for Fatal and Nonfatal Firearm-Related Injuries --- United States, 1993--1998
Gives the following approximate hit location percentages for non fatal shootings (assault/intervention type) in the US as:

arm 0.13
leg 0.33
head 0.14
torso 0.21
abdomen 0.16
undetermined 0.03

Our next step is to distribute the undetermined 3% into the other areas, so we don't have to deal with it later. This gives:

arm 0.134
leg 0.34
head 0.144
torso 0.217
abdomen 0.165

But this data only accounts for non-fatal shootings, how do we account for the fatal ones?

An Analysis of Wound Statistics in Relation to Personal Ballistic Protection (pdf file)

Tells us that, during the Vietnam war, hits with small arms fire in the following areas had the following chance to be fatal:

arm 0.01 (rounded up to 1%)
leg 0.05
head 0.7
torso 0.51
abdomen 0.4

assuming 1000 non-fatal shootings, we then go on to use the above numbers to determine the number of fatal shootings that would have hit the same location

[Aaron]

Interesting read. You need to get out more, but interesting read. =i)

[Crusher Bob]

Yes, and I practice with them four hours a day, so that when I meet a shadowrunner I can kill it. :D

Next up armor penalties:

I'm not that happy with how armor penalties are implemented in SR4, the way it's currently implemented and armor penalty generally means a big penalty since the check for penalties is based on armor vs (body x 2) but the penalty itself is based on armor vs body. So I'll present some ideas for more in depth armor penalties.

Helmets:
The main problem with helmets is that they effect your perception, of course you can add techno bells and whistles to negate the penalties.
Proposal:
Light coverage helmet (35% of head)
using my above data: IIIA provides 2 armor
gives a -1 penalty to hearing (perception)


Medium coverage helmet (covers 50% of head)
standard infantry helmet: IIIA, provides 3 armor
gives -2 to hearing (perception)

Helmet with face shield (covers 75% of head)
riot/bomb squad type helmet, IIIA, provides 4
gives -3 to hearing and -1 to vision

turtleshell helmet (100% coverage of head and neck)
only worn as part of complete suit, otherwise too hard on the neck, but provides roughly 6 points of armor (class III)
-4 to hearing and -2 to vision

So, a standard infantry helmet basically doubles a soldier's ability to resist damage.

Armor on the torso and abdomen
Armor on these locations is not as penalizing as armor on the arms and legs. The main problem is getting hot.

Cloth armor (I or IIA)
no penalties

Flexible armor (II or IIIA)
-1 penalty on extended physical tests (climbing running, etc) without cool environment or techno/magic cooling system.

Semi-rigid (III)
cooling (as above) and a additional -1 on physical skills (as enhanced articulation)

Rigid (IV)
cooling penalty goes to -2, -1 on physical skills, -1 reaction

Arms and legs
Much larger penalties than on the chest:

Arms
Cloth armor (I or IIA)
no penalties

Flexible armor (II or IIIA)
Slight loss of flexibility and speed gives a -1 penalty to close combat tests

Semi-rigid (III)
-1 to both close and ranged combat

Rigid (IV)
-1 AGL, -1 cooling

Legs
Cloth armor (I or IIA)
no penalties

Flexible armor (II or IIIA)
-1 Physical Skills

Semi-rigid (III)
-2 physical skills, -1 close combat tests, -1 REA

Rigid (IV)
-1 AGL, -1 REA, -2 physical skills, -1 cooling penalty

So the totals for someone in turtleshell (IV chest, abdomen, III head, arms, legs) would be:
-3 cooling, -3 physical, -2 reaction, -2 close combat, -1 ranged combat, -4 hearing, -2 vision
Without an additional cooling system and perception enhancments it can present some real difficulties.

'open' heavy armor
(plus whatever penalties from the helmet)

Full Suit (no helmet) IIIA torso, abdomen, arms, legs 90% coverage
-1 cooling, -1 close combat, -1 physical

Full Suit (no helmet) IV torso, abdomen, IIIA arms, legs 90% coverage
-2 cooling, -2 physical skills, -1 reaction, -1 close combat

of the concealed armor I statted out above, only the armored jacket has any penalty, with -1 close combat.

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The turtleshell suit might be a bit over the top, but them an HMG will go right through it.

Comments?

[WeaverMount]

Is this a though experiment or do you think that this is playable? Would you be willing to type out an example initiative pass pass with burst?

[nezumi]

Very cool. It seems simpler than I remember CP2020 being and it translates easily back to SR3. I didn't see how 'cooling' affects the game, nor did I see you actually include rules for shifting damage based on hitting someone in a particular area. My big concern with this is if you have a 70% chance of dying when hit in the head with any sort of small arms, given the called shot rules as they are, I can only imagine people always shooting for the head, so the called shot rules will DEFINITELY need to be revised. This does bring up the potential for 'AVS burst called shot to the head, bypassing armor and upping damage, booyah HEADSHOT! lolol'

[Buster]

Be careful with the stats on the website you listed. These statistics are not combat related gun shot wounds. Those statistics included all self inflicted wounds too. Notice the really high percent of leg wounds? Also most firearm attacks are 1) perpetrated by someone the victim knows and 2) executed at close range (less than 15 feet).

You should look for military and police related statistics, these stats are just drunks and domestic abuse cases. Nothing here to base game rules on.

[Crusher Bob]

The hit locations of the wounds are tracked by type. The type I picked out was listed as assault/intervention. Self inflicted wounds are tracked seperately.

[Buster]

[Crusher Bob]

I used the data on table 8 of my second source to confrim the data I had.

[Aaron]

Oh, yeah. Encumbrance penalties. I'd forgotten about those. Suddenly, dermal plating and cyberlimb armor make a lot more sense.

[Buster]

The second source is awesome. Notice the radical difference between hit locations: in Vietnam, only 5% of small arms injuries were leg injuries versus the 33% of the drunk/domestic-assault cases listed in the other site.

I would think the Vietnam stats would be the ones to use because the Vietnam stats are segregated into Small Arms where the other conflicts lump in artillery with the small arms damage. Furthermore, jungle warfare would be most similar to postmodern urban jungle warfare.

Beware of the Northern Ireland stats and notice their really high percentage of lower extremity injuries? This is because the IRA was intentionally targeting kneecaps. The motto: "intimidate, kneecap, exile, or kill" the enemy. In fact, knee replacement surgery technology has surged partly because of that conflict alone. Here's a source: http://www.cwnews.com/news/viewstory.cfm?recnum=23828

[TheOneRonin]

I really like those optional rules. I've already revised worn armor in my SR4 games so the protection they give is more on par with the NIJ standards than the way the rules are currently written.

But going by these rules, how would you stat out the implanted armor (i.e. Dermal Plating/Sheathing, Orthoskin)?

[Crusher Bob]

[edits of value of IIIA armor, was an earlier revision numbers)

Here we start getting into things requiring actual game philosophy decisions.
I'm trying to make the system roughly similar to SR4's in the end, but so that you can see all the knobs and decisions that went into it, so that you can twiddle with them if that's what you want.

Hit locations and damage
How too represent hits to the head are much more lethal?
1st idea is as follows: assume hits to the thorax cause 'average damage' and the lethal % for hits to that area does a pretty good job in representing SR4 damage.

So we get:

[Crusher Bob]

Since I have some spare time, I'll check the numbers for a much bigger gun (or the same gun being fired by a gun adept, assuming we'll keep hits add to damage).

Damage is 12 (-1) (6 (-1) plus six hits))

Naked Bob:
abstract: 11 damage
hit locations: 11.01 damage

Helmet Bob:
abstract: 10.33 damage
hit locations: 9.89 damage

Armored clothing Bob:
abstract: 9 damage
hit locations: 9.26 damage.

Interesting bits:
helmet Bob's chance of death is somewhere around 72%, because the helmet won't reduce the hits to the head to below a lethal level and hits to the thorax and abdomen are lethal as well.
On the other hand, Armored Clothing Bob will only be killed outright by a hit to the head, meaning that he has only a ~28% chance of instant death.

(ignoring dice variance in both of the above statements)

We'll also check turtleshell Bob vs the big gun:
(22 armor + 3 body)
abstract: 4 damage
hit locations: 3.89 damage

[nezumi]

Does armor reduce the damage of an attack before or after multiplying it? That could save Helmet Bob.

[Crusher Bob]

Multiplication is after soak is done.

The damage for helmet Bob using hit locations for the head looks like:

He is hit in the head for 7.5 (-1)

He has body 3 and 9 armor on the head. So he gets 11 dice to resist 7.5 damage.
He gets 3.67 hits and is looking at 3.83 hits of damage, multiplied by 1.5 means he takes 5.75 points of damage.

Helmet Bob vs the Big Gun ™:
He is looking at 12 damage, getting 3.67 hits on soak, leaving 8.33 damage for multiplication, which turns into 12.5 damage. Ouch!


You have to multiply the damage after soak, both the save the head and to prevent the arms of trolls from being bulletproof.

Example:
Buff troll (body 15) is shot in the arm with an anti-material rifle (8 (-12) damage) and 4 successes. He is wearing no armor on the arms. If the damage was multiplied before soak then the damage would drop from 12 to 6 and he would soak 5 of it. Doing it the other way, he soaks five, leaving 7 damage, then multiplied to 3.5 damage.

[pestulens]

I have always questioned the need for hit location (or an extensive called shot system) in games like shadowrun that already have a degree of success defect on damage. Since we also have a called shot to avoid armor rule this is doubly redundant.
I have seen systems with mead use of a similar system but they where much less complex otherwise than shadowrun. Warhamer fantasy roll play comes to mind, where armor provided a fixed protection value but only covered sertan portions of the body. Shadowrun is more fast paced (theoretically) and actions take longer to resolve.

[Crusher Bob]

Bullets and armor penetration. (When to convert to stun?)

This one is a bit harder. There's no real way to show my math on this one, since it was largely randomly manipulating numbers in excel until I got something that looked about right.

One of the main problems is differentiating the much greater penetration of rifle rounds vs pistol rounds.

So, my recommendation is as follows:

All rifle rounds are modified by subtracting one from their base damage and adding 4 to armor penetration values.

Using SR4 stock weapons, this gives us the following:

[Moon-Hawk]

[Crusher Bob]

My intention was that the assault rifle goes from 6(-1) to 5(-5). Firing AP bullets out of your assault rifle makes it 4(-9) and firing expanding bullets makes it 6(-1) again.

Firing AP bullets out of your predator makes it 4(-5) and firing expanding bullets makes it 6(+3).

[Moon-Hawk]

Okay. That's what I thought you meant.

It seems reasonable. I'm not sure how valid of a measure your "penetration total" is. Obviously a point of AP is not worth a DV, so simply adding them together isn't really a great measurement. If you're looking for expected damage against an armored foe, AP should really only contribute 1/3 as much to the consideration as DV, and against an unarmored foe it's worth even less. (nothing, in fact) So "penetration total" can be a bit misleading. I think a better metric would be DV-(AP/3).

Which brings me to my other question. Why are you trading 1 DV for 4 AP? Granted, the 4:1 trade-in rule sets a bit of a precident for that, but I would think that in this case you'd want to use the statistically expected values for a 3:1 trade-in. By doing a 4:1 trade-in, if you decrease DV by 1 but improve (see how I cleverly dodge the increase/decrease issue? ;-) ) AP by 4, then the expected damage against an armored opponent increases by 0.33 boxes. Of course, not everyone will be armored, but considering the ubiquity of armored clothing I'm not sure how carefully we need to be considering the unarmoed foe. I mean, if you assume that 1/4 of all foe's will be unarmoed then the expected damage breaks even, so maybe a 4:1 trade-in is good.

All in all, I have no objections. It seems like it accomplishes your desired goal nicely.

[Crusher Bob]

The penetration total is listed so that you can do quick checks on what kind of armor will convert it into stun. Before the penetration total of heavy pistols of 6 and assault rifles od 7 meant that an armored jacket would stop both rounds (assuming not too many successes). With the modified values, assault rifles have a penetration of 10, meaning that concealable armor will basically never convert assault rifle fire into stun.

I gave the rifles a 'free' extra point of AP because I think that SR greatly shortchanges the greater penetration of rifle fire.

[Moon-Hawk]

[Crusher Bob]

Armor and weapons:

1 Concealable armor covers less area than obvious armor of the same type. So obviously armored clothing (think armored uniform) might provide a bit more actual armor value than concealable armored clothing.

2 Calculating the exact coverage of armor is difficult since bullet wounds are not completely randomly distributed over the target area. Covering the right 25% of the surface area might provide 50% coverage in the armor calculation.

3 Armor that is 'open' is incapable of providing 100% armor coverage, shots from the side, top, etc still have a chance of getting through. Should there be an extra penalty for closed armor, on top of other armor penalties?

4 Helmets are generally rated for IIIA (good vs all pistols) protection. Helmets that provide more protection are difficult to make, both because class III and IV armor are considerably heavier and the physics of providing heavy armor to the head are somewhat more complicated.

Helmets
Light Helmet 35% coverage (2 armor, -1 to hearing tests)

Standard Helmet 50% coverage (3 armor, -2 to hearing tests)

Helmet with face shield 75% coverage (4 armor, -3 to hearing tests, -1 to vision tests, -6? to enhanced smell)

Closed Helmet (turtleshell type, only worn with full sit of closed armor) 100% coverage (around 6 armor, but is factored into full suit armor) (-4 to hearing, -2 to vision, enhanced smell useless)

Concealable armor
In order of descending concealability:

Light concealable vest: armor 4
worn under clothing
Class IIA, 75% coverage of thorax and abdomen

Light armored clothing: armor 5
(armored hawaiian shirt and armored shorts)
Class IIA, 65% coverage thorax and abdomen, 33% coverage arms and legs

Armored clothing: armor 7
(fully covering clothing such as a business suit)
Class IIA, 75% coverage of thorax, abdomen, arms, legs

Concealed Vest: armor 7
Class IIIA, 85% coverage of thorax and abdomen
-1 cooling penalty
An alternative to the armored business suit. You don't have to keep up with the style. On the other hand, you sweat a lot.

Armored Jacket: armor 8
Class IIIA, 85% coverage of thorax, abdomen, arms
-1 to close combat tests, -1 cooling penalty

Unconcealable Armors
Armored Fatigues: armor 8 [edit, was 9, mistake in excel file]
Class IIA, 90% coverage of everything but the head.
(Protects against shrapnel and greatly increased your odds of being presentable enough for an open casket funeral, what more could you ask for?)

Armored ninja suit: armor 10
Class IIA, 75% coverage of head, 90% coverage of the rest of the body.
(If you plan on sticking on a helmet, use the base value for armored fatigues instead)

Light full armor: armor 11 (no helmet)
Class III, 90% thorax and abdomen, IIA 90% arms and legs
-1 cooling, -1 physical skills

Heavy Full armor: armor 14 (no helmet)
Class IV, 90% thorax and abdomen, IIIA 90% arms and legs
-2 cooling, -2 on physical skills, -1 reaction, -1 close combat

Turtleshell: armor 22 (includes helmet)
Class IV, 100% thorax and abdomen, III 100% arms and legs
-2 cooling penalty, -3 on physical skills, -2 reaction, -1 on both close and ranged combat tests, -4 hearing, -2 vision, enhanced smell useless.

Of course, such a suit would have a cooling system, and all sorts of sensory enhancements tacked on...

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There are all sorts of gameable holes in the way I've calculated the armor values. Best not let the players loose on them. For example, wearing bullet resistant (Class I) panty hose pulled over your head (a CP2020 favorite!) would give you around 2 points of armor!

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Well, they are putting up the typhoon signal here in HK, will be back with the weapons in a bit.

[Crusher Bob]

Next on to weapons and making sure the numbers match up right.