Determining Damage- Realism

[Dauntless]

Okay, maybe my other post on Engineering was a bit too deep.

So here's one of my questions without so much of the background.  How can I figure out how much damage a certain weapon does?  While specifically I'm looking for guns, any form of kinetic energy damage counts.

Kinetic energy of the round only plays part of the role.  It's possible to have a high powered round go clean through a person and do less damage than a lower powered round that doesn't exit through the victim.  If you know anything about inelastic and elastic collisions, it partially deals with this concept.

The diameter of the round plays a part in determining damage, but is it more or less important than the kinetic energy?  In fact, could it be the momentum (or impulse) of the bullet rather than the kinetic energy?  The diameter of the round in part determines how large of a hole it's going to make in someone.  But a smaller round which tumbles can actually do more damage than a large round that do to its momentum will just burrow a hole in a straight line through you.

As I recounted in the other thread, there appears to be at least 4 other factors:

Round fragmentation
Round tumble
Round deformation
Round cavitation

I've a few ideas in mind how to correlate all this information together, but I'd like to hear a few other ideas or suggestions.[/url]

[Andrew Martin]

I've a few ideas in mind how to correlate all this information together, but I'd like to hear a few other ideas or suggestions.

Buy a herd of pigs, tie them to poles and start shooting them with a range of guns and ammunition; record your results. It's the only way to get the most accurate results unless you're the state executioner in a totalitarian state.

Once you've done this, you can then sell the results to arms and munitions companies around the globe.

[Ben O'Neal]

As I recounted in the other thread, there appears to be at least 4 other factors:

Round fragmentation
Round tumble
Round deformation
Round cavitation

I've a few ideas in mind how to correlate all this information together, but I'd like to hear a few other ideas or suggestions.

I have serious concerns over whether you need to bother with all of these factors. Why? Because they are largely random. One word. Dice. Use die, and instantly you can say "the use of die represents the random factors of how a bullet might travel through a person". If you roll low, it was a clean shot, if you roll high, it bounced around a bit and hit a few important things.

But I do have serious doubts about how an exit wound can be less damaging than a bullet that stops inside you.... unless it is poisoned. Hollow points are renowned for the massive size of their exit wounds.

Also, my final question, is if you are aiming for realistic combat, why bother with all of this? I mean, you get shot, you fall down in agony. No more fighting for you. (Ok, you could make it a bit more interesting and remain within the bounds of realism, but the point is that when you get shot, you don't give a fuck if the bullet tumbled or went straight, you just got shot!). On the other hand, if you are going to be modelling realistc medicine and first aid, then this stuff might be important for how well the soldier might heal.

-Ben

[Bill Cook]

I assume you're trying to create mechanics for gunfire for a game you're designing.

Capturing realism is like trying to count the stars in the sky; everyone has a different threshold.  Even after you get your mechanics the way you want, someone will take a look and say, "Hey, you didn't get that part that's so important to me," in different words.

So regardless of whether you necessarily understand it perfectly, what's so important about role-playing gunfire, to you?

* * *

OT: one to two weeks back I had this big breakthrough with a game I'm designing when I realized that all weapons do the same amount of damage.  Now, I know that's not literally true, but it's a game truth that facilitates my goal, which was to normalize what a TROS player would call Margin of Success.  I differentiate weapons in other ways (i.e. constraints on defensive actions, different dice counts for defense to different types of weapons, etc.).

After the changes I made, any weapon could hurt and kill you, in one to more blows, limited by appropriate defense.  It's not Newtonian physics, but the demo rocks.

[btrc]

What I'm using in EABA to good effect is a model like this:

1) Weapon does N six-sided dice of damage (+1 or +2), like 4d+2

2) Armor is similarly rated.

3) Armor subtracts from damage, and you roll the remainder.

Benefits:
1) If you have an armor that you know will stop a bullet, it will always stop that bullet. EXAMPLE: a 9mm in EABA is about a 2d+1 attack. A level II bulletproof vest is about a 2d+0 armor. The 9mm does exactly 1 point of damage (blunt trauma).

2) On the other hand, any amount larger than 0d+2 that penetrates armor has a variable damage, so you can have the effect that it was just a graze, or it hit something vital. EXAMPLE: A 3d+2 attack vs. a 2d+1 armor does 1d+1 Hits to the target. A 5d+1 hitting a 2d+0 armor does 3d+1 Hits.

Location specific effects add to damage -after- penetration, and may also have location-specific caps on damage. EABA subtracts for the arms and legs, and adds for the head (with a minimum of at least 1 point if 1 point penetrates armor).

I'd also note that EABA has a declining scale on damage. The more you've taken, the harder it is to get further effects. That is, shooting you in the arm twice does not do twice the damage as shooting you in the arm once. You need to model this somehow to reflect the real world cases where people are shot several times and survive, or are stabbed dozens of times and somehow pull through.

Greg Porter
BTRC

[simon_hibbs]

For the ultimate resource on this kind of stuff, see if you can find a copy of 'Guns, Guns, Guns' by BTRC. It's a complete firearm design system, similar to the vehicle design systems you often get in SF games. It includes a formula for calculating damage that takes into account bullet velocity, diameter and such. However...

Also, my final question, is if you are aiming for realistic combat, why bother with all of this? I mean, you get shot, you fall down in agony. No more fighting for you.

This is spot on. Mega Traveller, still the best edition of Treveller yet published, did precisely this. Damage was a fairly low-resolution affair. The results were basicaly wounded (with attribute penalties), incapacitated and dead. A magazine article in the Mega Traveller Journal took this raw data and built a whole medical treatment system on it, for determining where the damage is, the exact form of it, short and long term effects, appropriate treatments and such. This strikes me as being an ecellent way to proceed - generate just the information you need, as you need it in the game.

Simon Hibbs

[Dauntless]

Maybe I should claify what I mean by realism.

I'm not looking so much into an accurate 100% modelling of reality, but rather, something that's close enough so that you think, "this could really happen", that there's 100% consistency across the board, and that it doesn't require much (if any ) suspension of disbelief.  The simulation of damge affects here has one main goal....consistency.

Many game rules have arbitrary or inconsistent game rules when it covers game damage.  Some have some basic principles to guide the damage ratings like, "it's a bigger caliber round so it should do more damage".  But since my game allows for the creation of new guns, I can't just set up arbitrary rules for determining damage.  There's another design aspect for why I want to determine the many factors that go into damage determination.  I want to be able to make different guns that seem similar have different characteristics.

As for suggestions to reading Greg Porter's Guns! Guns! Guns!, I've had the original since 1988, and I have the pdf version as well.  It's been a great inspiration, but I'm going to be doing a few things differently than he is a I outlined in the Engineering post.  For example, I'm going to be seperating raw Damage (or Wounding Capacity) from Penetration.  I'm going to include much more bullet characteristics as well, such as cross-sectional factors (to determine drag and penetration...this is the "shape" of the bullet) as well as the other mentioned factors in determining damage.

someone mentioned that the Damage factors I mentioned are random.  While there is a random element to it in some  cases, in others, there is a consistency in one or more of the factors.  Round tumble is very often a consistent characteristic of a round fired out of a gun.  A great example is the first M16 rifles when they entered service in Vietnam.  Unlike today's M16A2 and M16A4 which are given mediocre man-stopping power ratings, the first M16's were noted as quite lethal.  There were two main reasons for this.  The first was that they put more grains of gunpowder in the round, and the second was that the original had a rifling of 1:12 (one twist in the barrel every 12" to produce spin to the bullet).  This meant the round carried more energy and more importantly, the bullet had less spin, and therefore the round tumbled more.  Because the round tumbled, sometimes the bullet wouldn't even hit the target nose-on.  This meant the round also tumbled through the human body rather than puncture it with a nice clean hole.  The top brass in the army didn't like the accuracy of the first M16's though, so they increased the rifling to 1:7 and changed the gunpowder.  The change in gunpowder decreased the fouling (plus they added a chrome liner in the receiver to reduce dirt muck-ups) and also slightly decreased the velocity, but the improved rifling also made the round more accurate but it didn't tumble as much when it hit the body.

So the newer M16's tended to drill nice holes into people whereas the older one's were reported to literally blow people's limbs off or even blow off heads.  The tradeoff was very poor accuracy and range with the older M16's.  From talking to other people who have fired other assault rifles from other countries that also fire 5.56mm NATO, they've all said one thing...the M16 accuracy sucks compared to FAMAS (France), the SA80 (England), or the Steyr-Aug(various other countries).  Same round, but different gun produces different accuracies and even different damages.

And this all leads back to how do you determine damage?  Well, I'll put up these bookmarks as they helped me out some and they might help other designers as well.  Many agencies have a HUGE interest in how lethal guns are, and to think there is no research done on it is naive at best.  While no one does live testing on humans, some countries have done tests on animals (not to mention anecdotal stuff from hunters) and even here in this country, test rounds have been fired on cadavers.  So it's not just gel blocks that a lot of this data comes from.  And of course there's also hospital data.  What I'm really looking for but don't know if I can find because it's classified are any military reports.  I know they exist, but haven't been able to find any information.  And I don't know if a Freedom of Information Act request will go through in order to do "Roleplaying Game research".

But anyways, here are a few websites with some useful info:
http://medlib.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNINTRO.html
http://www.mindspring.com/~ulfhere/ballistics/wounding.html
http://www.steyrscout.org/terminal.htm
http://www.isl.tm.fr/en/scientif/pages/d1/d1_e_atb.html

http://medlib.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNINTRO.html

[Dauntless]

Another point about getting shot....sometimes you get hit and don't go down, at least not immediately.  The M16 has been getting a lot of flak recently because there have been quite a few battlefield reports that it's taking more than one solid hit by an M16 or M4 round to take the bad guy out of the fight.  In fact, the Army and Marines are both looking at a new caliber round to address some of the problems the troops using 5.56mm rounds have been facing (the scuttlebutt right now is that the army is looking at a 6.8mm round).

So really, getting hit, even in the chest or stomach may not take you out of the fight depending on the round, the person's health, and perhaps more importantly, their state of mind.  And this in turn is important because if you aren't hors de combat with the first shot, you might be able to take out a few more people.

Famous case in point, the M1911A1 (or the "colt 45") was developed shortly after the Filipino Insurrection.  the gun was developed because the Smith and Wesson 38 calibre that was standard issue of the American troops wasn't putting down the Filipinos with even spotty regularity.  There were many documented cases of Juromentados (my mom says this basically translates as "religious fanatics") getting hit at point blank range with all 6 rounds, and they kept coming to kill the soldier (there were also documeted cases of some filipinos cutting Springfield rifles in half with their Kris swords).  So, the US decided it needed a sidearm that would literally blow a person off their feet...and the legendary 45 was born.

This is a reason why my Damage modelling system keeps track of different types of damage (I don't use hit points, but rather a comparison of a Damage Rating to a Status System).  For example, I differentiate damage by structural capacity (broken bones, torn muscles, torn cartilage), Trauma (life critical wounds),  Neurological/Motor (getting stunned, paralyzed or knocked unconscious), Support (blood loss, dehydration, hunger), Mental and Physical Fatigue.  Guns generally do a combination of tearing and penetration and this in combination with the location hit determines what kind of damage is done (well, that and the Damage Rating of the gun).

[Dauntless]

BTRC-
I actually much preferred Greg Porter's older games Timelords and Spacetime when it came to damage modeling.  Again, his works have inspired my own.  In that sense, EABA was a disappoint to me because it didn't feel as realistic as his earlier stuff.

While I agree that people can get shot multiple times and live, I didn't like the fact that the more hits a character takes, the less each succeeding damage does.  Most health care professionals are aware of shock and how lots of tiny effects can escalate into one big one.  Pain and blood loss can trigger other systemic reactions which aren't good for the human body.  But I'm definitely including rules which make sure that health isn't "ablative" (every wound takes away from a life meter).

While my mom's a great resource in an anecdotal way (she's been a nurse for 40+ years, with a quite a few of those in ER, including Cook County hospital....yup, that ER), I still need to do a little more digging on this.  But I did very much find Greg Porter's game of Timelords and Spacetime to have a very interesting way of modeling damage.

[btrc]

For wound effects, the Army Medical Service did a report after WWII on wounds and wounding, using field hospital data. With grisly pictures as I recall. Gunshots, shrapnel, etc.

For more modern info, look up books on emergency room medicine. These will deal with the nature of, effects and early response treatment of gunshot and knife wounds, among other things. More grisly pictures.

And remember, not everything you hear about weapons is true. The .45 has a lot of hype, none of which is apparently backed up by either theoretical figures or real-world ballistic tests. For instance, if the M-16A1 was as unstable as noted, you would have trouble deliberately hitting anything with it. Not a problem when you have hundreds of guys filling the air with lead, but for a roleplaying standpoint, I'd rather have my bullets flying straight and hitting what I aimed at, rather than flying through the air sideways and causing significantly more damage...to something other than what I was aiming at. Also note that if a bullet is travelling say 600m/sec, then it is only spending several -thousandths- of a second in a human target. Quick calculation: If a bullet decelerates from 600m/sec to 100m/sec on its way through a 20cm target (shedding 97% of its energy in the process), then it spends about 1/1000th of a second in the target. There's only so much tumbling -any- bullet can do in that interval.

If the tumbling, expansion or other bullet geometry helps the bullet shed energy, that's generally what does the damage, not any increased mechanical tissue damage caused by a larger bullet cross-section.

When an officially adopted weapon gets a lot of hype to about its effectiveness, it improves the morale of those using it, and those that have a vested interest in the weapon (manufacturer, military procurers, those who voted for it, etc.) will tend to agree, despite any later facts to the contrary. The current UK service rifle (L85 series) is a current example. Took years for the gov't to admit it was unreliable, inaccurate, too heavy and overly complex, despite numerous field reports of all of the above. For instance, despite being a bullpup design that is decades -newer- than the M-16 series, the UK's L85A1 is still -heavier-. A classic case of "We adopted it, therefore it must be a good weapon." I got roundly criticized by a few Brit gamers for pointing out the L85's flaws in the early 90's, but oddly enough, they stopped emailing me after I gave them proof to support my assertions...;)

Look for third-party info about weapons before believing any anecdotal hype or national bias.

Greg Porter
BTRC

[btrc]

BTRC-
While I agree that people can get shot multiple times and live, I didn't like the fact that the more hits a character takes, the less each succeeding damage does.  Most health care professionals are aware of shock and how lots of tiny effects can escalate into one big one.  Pain and blood loss can trigger other systemic reactions which aren't good for the human body.  But I'm definitely including rules which make sure that health isn't "ablative" (every wound takes away from a life meter).

True enough. I'll admit EABA is 'less realistic', but I think that it is 'realistic enough', especially when you use the advanced rules.

FYI, my basic design rule is that one 9mm to the head should result in immediate incapacitation and possible fatality on a normal person. If a system doesn't pass that basic test, it should be prohibited by law from using the word 'realistic'...;)

Look at the declining damage rule in EABA in terms of -effect-, not 'it does less tissue damage'. If you break your arm, it will have a certain game effect. If you break that arm in another spot, it might be the same amount of -tissue damage- as the first break, but in terms of -effect-, your arm really isn't that much 'more useless' than after the first break. Especially for the same 'hit location', multiple hits don't have a straight additive effect. It doesn't matter -how- you model it, but it is something that -should- be taken into account for a realistic damage system. It could be something as simple as saying that a 'broken' or 'incapacitated' or 'took all its hits' effect renders a body part useless, so you only count the actual damage for rolling shock effects for later hits on that body part.

Greg Porter
BTRC

[Callan S.]

I'm not looking so much into an accurate 100% modelling of reality, but rather, something that's close enough so that you think, "this could really happen", that there's 100% consistency across the board, and that it doesn't require much (if any ) suspension of disbelief. The simulation of damge affects here has one main goal....consistency.

I'd like to take a moment to look at what your design goals are, here.

Firstly, is this design intended for personal use only? I ask in relation to the impression you want to give of "this could really happen"

Now, I've never been in a gun fight, or even fired a gun. I've read various posts about things like bullets bouncing around in a targets body. As much as I believe it, I know that all these stories go through the 'I can talk the talk real tough' process before they get typed out.

Thus I have no idea how it 'could really happen'. I am not alone, there are many like me in the RPG demographic.

So basically you could write up anything and to me the difference between your ultra realistic system and one which makes you gag (b/c its so unrealistic), could be completely equal in my eyes.

In fact the one which makes you gag could win out/be purchased, because it could be a lot simpler.

Which leads to just how much suspension of disbelief will be jarred by the system. In a really awful system where things are all over the place, sus of disbelief can really be jarred and take a beating. But the thing is, suspension of disbelief is getting over the fact its not real, suspending the disbelief of it all.

This is important, because it doesn't matter how much detail you put in the system or how realistic it is, in terms of suspension. How much effort a user will put into suspending disbelief is more a matter of faith than math. All the handling of bullet velocities in the book doesn't do anything at a logical level for them. Suspending disbelief isn't a logical thing to do, its handled by the emotional side of a person. All the bullet velocity handling rules don't convince a player like scientists use evidence from experiments to prove theories to another scientist. It instead convinces people like a salesmens pitch, appealing to their beliefs and emotions.

Which means you can go long and hard into sweating the small detail, getting them just right, and unless you can somehow show and sell how much detail you went into there, it'll have been a waste of time.

On a side angle, a recent post in RPG theory was about RPG designs missing the fear and confusion of combat. It's basically a suggestion that the impression of chaos in combat is more likely to support suspension of disbelief for a game. I mean, suspending disbelief for a combat that is crazy and chaotic, that's easy. Suspending it for one where there is no focus on that and I know the exact number of times a bullet tumbled in my foe, which if I were there I'd never know that? Suspending there is harder, I just can't believe in technical nuance as easily as I can believe in a focus on how chaotic it would be.

On consistancy, what do you mean? Consistancy in relation to other system effects? That's quite straight forward to do (if requiring work), eg a cartoon type game can have weapons that are quite consistant with each other, despite the looney theme of the book. Internal consistancy? Or do you mean consistancy with the real world? It can't be the latter because you quoted 100% consistancy, and that would require zero abstraction.

[Dauntless]

My comment about things seeming like "it could really happen" was made in general and didn't necessarily reflect specifically combat per se.

That being said, the perfect simulation of reality is not my #1 priority.  My #1 priority is rather consistency based off game reality.  In other worlds the game rules create reality (with some help of GM interpretation of course) and this game reality should be very consistent.  In parallel with this design goal, I want the game rules to clsoely mirror the real world reality.

What do I mean by consistency?  It means that the results should be based on an underlying set of laws, principles or rules.  In effect my rules are the cause, and what happens in the game are the effects.  Inconsistent rules create effects which don't seem logical, rational, or plausible (according to the game setting...what may seem illogical or inappropriate for one setting may be appropriate for another).  These laws or rules should apply in every circumstance.  For example, in the real world, ballistics has to obey the laws of physics, and wound trauma has to follow the laws of human physiology.  

Game systems can become inconsistent when the underlying principles or laws are either ignored, not thought through fully enough, or simply don't exist.  Case in point, I was just on a forum discussion board on herogames.com where someone asked why axes were so much better than swords.  In Fantasy Hero, 1-H axes had a lower STR min and did more base damage than a 1-H sword...and swords were more expensive.  Clearly there was an error in thinking here.  Axes should have a higher base damage, but they should not have a lower STR min (unless the designer wanted to simulate that it's easier to increase the DC of an axe compared to a sword...in which case he missed the point that it also means that a lower strength character can do more damage with it than a stronger character with a sword).

The Hero system is an effects based system where the underlying causes are not considered because it is either irrelevant or because there are too many possibilities.  I want my system to consider both the cause and the effect, hence eliminating many unecessary inconsistencies (you'll never get rid of all of them, but that's what GM's are for...but a good rule set will minimize this need).  But the Hero system allows players and the GM to create weapons or equipment for any genre imaginable because it only models the effect and not the cause.

But this is also the root of its inconsistency.  My game system has a much more restrcted confine of setting, and the rules were designed to create a very "grim and gritty" atmosphere with lots of tactical choices.  I also took the approach that this is a Roleplaying Game.  I've noticed a trend for many games to emphasize the Roleplaying part while minimizing the Game part.  I want it to be a good blend of the two.  Even the roleplaying will have game mechanics to encourage or discourage character behavior (and hence how the player controls his character).

I'm creating these damage rules because I want players and the GM to be able to create weapons (any weapon up through a certain technological period) for their game.  Because the GM can create his own weapons, the playtesting must already be built into the design rules.  This is another potential flaw in effects-based systems like Silcore or The Hero System.  Hero requires the GM to scrutinize a design to make sure there has been no min-maxing or out-of-context equipment (or characters), and the same can be said of Silcore (for example, in the rules for Silcore, it says there's nothing stopping anyone from loading 12 beam cannons on a small mech...if it has to be done, the engineers will find a way to do it).  That's precisely what I want to get away from, and what I see as potential inconsistency.

The flaw with my system is that it is constrained to the technological limits that are implied within the game rules.  For example, suppose that tomorrow we develop superconductors....well, my rules don't allow for it until about 2020.  Another points lies here as well...I'm creating rules for equipment creation up through about the next 100 years after which I'm stopping.  I don't know how our technological limits will be, but the game rules provide the virtual reality that all the effects are based on.  The game effects may not always jibe with our own real world, but they will be consistent as much as possible within the context of the game world.  So my design goal as a second priority is to model our own real world close enough.  Partially so that we can relate, and partially because reality is a great way to provide a framework of design rules with built in checks and balances.

[Dauntless]

About the fear and confusion angle...I've been following Sydney's thread closely and offered some of my own thoughts on what to do.  

I come from a wargame background so modeling this confusion and fear is very important to me.  I think there's a fine line where roleplaying begins and Game ends, and where Game begins and Roleplaying begins.  Where you see this line is how you develop the rules to handle these kinds of situations.  If you lean towards the roleplaying line, then the player should act out his character model the fear and confusion.  If you fall towards the game line, then you model how the fear and confusion affect the character's ability.  Ideally you do both.

Is technical nuance unnecessary to model this chaos?  Not at all.  The technical detail is there to support and guide the roleplaying.  The game rules determine the effects, and the shared imagining has to fit within this context.  For example, let's say that a character has to make a coolness under fire check if a shot comes very close, and the character fails this fear test.  He fails the test but not badly, so the player says that his character hits the dirt and tries to find  any cover to protect him.  If the character failed badly, the player might say that his character hugs the ground, hands over his head in a fetal position whimpering for his mommy.

To me, I find this more realistic than a character charging a MG42 gun position while all his friends are turning into fair approximations of hamburger while he froths at the mouth screamig at the top of his lungs that the vermin Jerry's are going to pay.  Now instead, if the player has to make a roll against his willpower, perhaps having to spend some of his precious Task Enhancing points or metagame points to achieve that level of heroism is something else.  As my grand dad always said, "if it comes easily, it's not worth it".  And games that allow players 100% control of their characters in all circumstances without making them pay for it in some manner is not just unrealistic but ultimately not as rewarding either.  After playing some harder edged games that were more grounded in realism, I came to appreciate that the victories were hard fought and hard earned.  It made victory (and defeat) that much sweeter.  In many ways, I scaled down the strategic necessity of a commander to always be in control of his troops down to the indidvidual, but instead of the individual controlling his troops, he's trying to control his emotions.

So the technicalities don't take away from roleplaying, rather they supplement it.  Much like a director telling an actor how a scene should be played out, that's what my rules do.  The players frame the scene with their actions, the dialogue and acting  still in the hands of the player, but the direction is in the hands of the "director".  The more concrete the rules are the more information you have at your disposal.  I don't see this as taking away creatvity.  It does take away dramatic license, or the freedom to act out the scene as you envision in your head.  But it doesn't take away creativity.  Instead the concrete rules provide the confines within which the roleplaying description (the shared imagining) should take place.

[Mulciber]

Hello,

I would offer that Vincent has a few words to say on just this subject, within the context of his game. If one didn't care for profanity, I'd advise against following the link.

Best,
Will