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Engineering Manual - Ballistics

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While working on STRIKE, I realized that I had to flesh out the "Kit" part of the engine (STRIKE stands for Strategic, Tactical and Roleplaying Integreated Kit Engine). The RPG game system is split into two parts, a Core system which all genres, settings and premises must have, and a Plug-in system which provides mechanics, attributes, the chargen process and other elements which are more genre or settings-bound. I realized that someof the Plug-Ins could be cross compatible with all 3 levels of gameplay (strategic elements are derived from tactical elements, and tactical elements are derived from roleplaying elements). I wanted to create an Engineering Manual which would be a Plug-in resource for players to create weapons, vehicles, and system equipment (such as communications or sensory gear). Because my game is quite crunchy and more grounded into the sense that "this could really happen" and "these are the things I''d have to worry about if I did this in real-life". So this engineering manual is in many ways a mod-tool to help create new things or tweak existing ones. Right now I''m trying to develop rules for weapons. Being a neophyte computer programmer, I''ve been abstracting the concepts as much as possible in order to seperate the essence of something from its actual behavior. I''m doing this so that I can take what''s common about weapons and create the same traits to describe them. For example, I''ve broken weapons down like this into these Abstract Data Types: The Damage Object(DO) - The DO is what actually delivers the form of damage to the target. It is the means by which the DO''s energy is transferred to the target to change the target''s current state. In the case of a gun, it''s a bullet, in the case of the sword, it''s the sword itself. In the case of the former, it''s an Indirect DO, and in the latter it''s a Direct DO. The Delivery System - How does the DO get to the target? There can be an Internal Delivery System (such as a rocket), an External Delivery System (like a gun or bow and arrow), or Self-Propelled (most forms of energy weapons like lasers where the DO is also the means of propulsion) Damage Form - What form of damage does the DO do? Generally, it is either kinetic (a moving object colliding with another object), energy (a form of energy releasing its energy to the target), or Pathogen (a catch-all that describes any vector which can state change one of the Damage System Tracks of a character....for example, diseases, poisons, mental trauma, etc) Damage Type - How does the DO affect the state change on the target? In Kinetic DO''s, it is physical damage and can be either penetrating, tearing, crushing, cavitating or cutting. Energy forms can either do Heat or Radiation damage. Pathogens directly affect either an attribute, or one of the Damage System Tracks (of which I have several). Right now, I''m concentrating on developing normal conventional weapons with the above abstractions in mind, and I need to make the above elements more concrete. I''ve been very much influenced by Greg Porter''s excellent Guns! Guns! Guns!, but I think there can be some room for improvement. For example, 3G! combines the element of kinetic energy and pressure into one value...the Damage Value. I think that''s problematic. I want my game to seperate a round''s ability to penetrate armor seperately from how much tissue damage it does. This leads to the next problem. From doing a little research on Terminal Ballistics, the general consensus now is that total Kinetic Energy of a round doesn''t really have that much of an impact on how damaging a bullet is. The greatest determiner of Wounding Capacity (WC) is how big of a hole it creates in you. For example, some very high powered rifles with solid metal jackets drill nice clean holes in their targets, whereas a slower bullet when it hits the body often tumbles, leaving a very jagged wound track inside the body. Moreover, the bullet may not exit the body, and hence, 100% of the kinetic energy of the round is absorbed by the body. So this leads me to Question #1: How to determine a Damage Rating (Terminal Ballistics) . From my research, it seems there are a couple factors which help determine how big of a wound cavity you leave in the target. Round Tumble- The more yaw or pitch a bullet has, when it hits the target, this becomes more pronounced, causing the flight path of the bullet to go in less of a straight line, and more into a jagged pattern Round Fragmentation- Some rounds will actually break apart upon hitting a body, so that multiple wound channels are created Round Deformation- Hollow Points take advantage of this. When the bullet hits a target, it mushrooms creating a much larger wound channel Round supercavitation- The russians came up with a round that when fired, creates a wall of supercompressed air around the bullet (the nose of the bullet has a slight concave curve to it to create this pocket). When the bullet hits the target, this pocket of air collapses doing two things. First, it creates a shcokwave in the human body. Research says that this probably only has minimal impact on tissue damage. But the other effect is that when the air pocket collapses, it makes the bullet pitch or yaw, making the bullet tumble inside the body. NATO forces don''t use this round (even though it''s not specifically forbidden by the Geneva convention) as they feel it is inhumane. Does anyone know of any good ways of how to model this or of any good sites that can explain how this works better? Question #2: Develop the ammunition first or the gun first? In 3G!, you sort of co-develop them at the same time. Or rather, you decide on a Damage Value, and from that you determine what the muzzle energy of the gun is, and the base energy of the ammunition. However, in my design system, Damage isn''t directly correlated to the energy of the gun. So I was thinking that I''d probably have to design the gun first. I was thinking it''d go something like this: 1. Figure out what kind of aiming ballistics you want (how accurate it is...generally dependent on velocity and length of barrel) 2. Determine what kind of damage ballistics you want (how quickly does the round lose its kinetic energy?). Rifle rounds keep their energy longer than pistol rounds. 3. From the generalizations above, figure out an approximate velocity of the gun you want as well as the bullet''s inherent characteristics like mass, length/diameter ratio...or caliber (these should be independent of what theExternal Delivery System provides). 4. Determine how much energy the Delivery System needs to propel the givenmass of the bullet to the desired velocity. 5. From this, determine the mass of the different components of the External Delivery System (the Receiver, Action, Feed Mechanism, Barrel and Ergonomics) My system will probably at least seem very familiar to anyone who''s used Guns! Guns! Guns!, but there will be some slight differences. Namely how Damage and Penetration are calculated, and mine will have a few extra steps (like considering the cross sectional area of a round to determine Drag and Penetration). But these few small changes means that I can''t follow in the footsteps of 3G! either, because some of the steps rely on knowing the Damage Value which I don''t use.

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About the Delivery system, what would you say about a sword? External?

I think that the damage type depends on the damage form, the physical shape of the DO, the movements that the DO since it touchs the target, how fast the DO is moving, how rigid or flexible the DO is, and how much strong the DO is, and how much does the DO weight. Of course you might want to take some of those out, so it doesn''t becomes too complex.


Question 1: Just as you say, put together all the factors that you found during your research to determine how big the hole is in a formula, and that would be the result.

I didn''t understood your question next question.. you talking about 3D modelling? or about how to apply this factor effectively in a realistic way?

Question 2: I think you should develop the ammunition first, since it''s the one that is going to deal the damage and depending on what kind of weapon you need to fire that ammunition you design the gun.

Sorry for taking so long to answer your post!

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quote:
Original post by Dauntless
So this leads me to Question #1: How to determine a Damage Rating (Terminal Ballistics) . From my research, it seems there are a couple factors which help determine how big of a wound cavity you leave in the target.

Round Tumble- The more yaw or pitch a bullet has, when it hits the target, this becomes more pronounced, causing the flight path of the bullet to go in less of a straight line, and more into a jagged pattern

Round Fragmentation- Some rounds will actually break apart upon hitting a body, so that multiple wound channels are created

Round Deformation- Hollow Points take advantage of this. When the bullet hits a target, it mushrooms creating a much larger wound channel

Round supercavitation- The russians came up with a round that when fired, creates a wall of supercompressed air around the bullet (the nose of the bullet has a slight concave curve to it to create this pocket). When the bullet hits the target, this pocket of air collapses doing two things. First, it creates a shcokwave in the human body. Research says that this probably only has minimal impact on tissue damage. But the other effect is that when the air pocket collapses, it makes the bullet pitch or yaw, making the bullet tumble inside the body. NATO forces don't use this round (even though it's not specifically forbidden by the Geneva convention) as they feel it is inhumane.

Does anyone know of any good ways of how to model this or of any good sites that can explain how this works better?


I think there are two basic approaches to destroying a target:

1. Hit something essential that the target cannot function without. This can be achieved either with extreme accuracy (shot to the head etc) or by increasing the damaged area so as to maximize the chances of hitting something important.

2. Inflict such massive, superficial damage that the target simply becomes non-viable. In the case of a soft target, this involves making a big enough hole for them to bleed to death, in the case of a hard armoured target, this consists of screwing up enough of the target's infrastructure and non-essential functions so badly it is essentially useless.

For 1. the size and density of critical areas is important - you can probably compare the flight volume of the bullet through the target and compare it to the density of critical areas on the target, adjusted for any sharpshooting ability the firer has. A guy spraying AK47 fire is pretty much shooting randomly, so he won't get much of an adjustment - a sniper on the other hand, is spending a great deal of time actively aiming for these points, and so gets a large adjustment. If a critical hit is scored that effectively means insta-death.

If a critical hit isn't scored, you're looking at a 2. scenario. Here I think you need to have an idea of how much infrastructure damage a target can take before it becomes non-functional. You could calculate the infrastructure damage by comparing the flight volume of the bullet through the target and the volume of the target, and subtracting that percentage of the target's current 'infrastructure' points from it's total. Obviously, an object with a large volume, such as a tank, is going to be very resistant to this sort of damage unless it really is massive - i.e caused by some kind of explosive round. Drilling little holes with high velocity penetrators isn't going to do a hell of a lot, unless you strike a critical system.

As for how you actually model the flight volume through the target - good luck. Really, this will depend on so many factors it will be nigh on impossible to simulate accurately - at some point you WILL need to abstract this or make some basic assumptions.

quote:
Question #2: Develop the ammunition first or the gun first?



One thing that worries me is the probability of creating and fielding a non-viable weapon without realising it. Suppose I type in a bunch of numbers more or less at random, and end up creating a high explosive grenade launcher that has a range of 2 feet, and thus invariably kills the guy equipped with it. This sort of thing simply doesn't happen in real life. In fact, the military tends to buy weapons from contractors which have already been tested and met certain criterion, such as purpose, weight, and cost. Perhaps you could 'define your criterion' and allow some sort of 'weapon generator' to create a series of weapons aimed at meeting your criterion, with some built in sanity checking to make sure that none of the results are too silly?

Anyway, to answer the actual question - it's common for military forces to define an ammunition standard, and then develop weapons - and ammunition - around this standard. So you could define your basic ammo type - calibre, length etc - define a weapon capable of launching this ammunition a respectable distance, and then define subtypes of ammunition (hollowpoints, explosive rounds etc)

[edited by - Sandman on June 1, 2004 1:06:01 PM]

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Coz-
I''ve been trying to figure out if melee weapons are External Delivery Systems DO''s, or are Self-Propelled DO''s. I''m starting to think it would make more sense if I made them Self-Propelled. The logic is that a melee weapon is really an extension of the human body, so the weapon (the human body) is its own means of delivering itself to the target. This also means that the Kinetic Energy of the melee weapon is dependant upon the wielder.

I wish question #1 was as easy as that. I''m currently doing some research to figure out if there is consistency within ammunition types and weapons to create the 4 different types of Damage factors (Tumble, Deformation, Cavitation and Fragmentation) or if it''s more random (the deformation is usually not random I know for sure).

As for #2, what I mean is that designing a gun is sort of a chicken or egg question. Which one should you design first? If you design the round first, the gun has to be able to fire that round, and if you design the gun first, then you have to create ammunition which can be fired from it. Many of a bullet''s ballistics characteristics are dependant both internally within the round itself (Internal Ballisitcs, such as length:weight ration, cross sectional area (which affects drag and penetration), starting kinetic energy, mass, density, deformation ability, fragmentation ability, etc etc. Then the gun also applies factors which affect ballistics (external ballistics) and this includes things like rifling, muzzle kinetic energy, gas disturbance (the gas pushing the round out of the barrel can also be unstable and cause the bullet to tumble more...this is what muzzle brakes try to relieve) etc etc.

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Sandman-
Where a target gets hits is definitely important. I think there are 3 fundamental criteria that determines damage:

1) Target location (where the damage path track is)
2) How wide the damage track is
3) How deep the damage track is

The first step determines what kinds of physiological effects happen. For example, if you take a 12ga shotgun round to the knee at 20ft, it''s probably going to blow your calf off....defintiely painful (in my system this would equate to the Pain meter), definitely structurally damage (the lower leg region would be gone), pretty badly bleeding (the Support system damage track would take off about half), the shock value would be moderately high, but the initial critical damage would be moderate but not that severe. It could eventually become fatal because the bleeding will cause the Support Damage Track to lose points every round, and this combined with the moderate shock rating could throw the victim into Shock and death of blood loss. But if the victim receives medical attention within 5 minutes or so, he has a pretty good chance of living. It will be extremely hard for the character to do much else than grip the stump at the end of his thigh and scream in pain, but it''s also possible that he might still be able to perform some actions (albeit at a minus due to pain).

However, place this same damage in the head...and well, roll up a new character. The critical damage would be off the charts and no matter how healthy the character is or how pain intolerant...no brain = no life.

#2 and #2 are important though, because they also determine how wounding the damage could be. Hit someone as hard as you can in the chest with a punch, and you might knock the wind out of him, or if you''re Bruce Lee, you might crack his sternum, but otherwise, the damage probably won''t be that severe. Now, whack the guy in the spot with a warhammer with all your might, and he might have a burst heart, or the sternum piercing his heart. In both cases, there was no wound cavity to speak of, but the kinetic energy creates a shockwave which can damage tissue, or it can break bones, which in turn with the force applied can pierce internal tissue.

As for the possibility of creating unviable weapons, it technically is still possible to create a gun that shoots a bullet so that it only flies 10 ft before hitting the ground (or worse, that grenade), but at least you''ll immediately know if the weapon is useful or not. Some roleplaying games which allow for the creation of weapons are not so clear cut if a weapon will be useful or not until they are actually used. Many of these game systems use "effects-based" rules. In other words, they don''t care about why an effect was achieved (the causality), they only model the effects themselves. With games like this, it''s possible to create a weapon the size of an assault rifle that can destroy tanks, the only limiting factor being that they cost more points to own (the point cost is determined by how useful the effect is). The advantage of such a system is that it can model any genre in any setting, because technology is moot.

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