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Quick Vehiicle Stats


Atgxtg

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2d8 doubled for impale.

Ah. Yeah, we pretty much decided to dump impales as such, but will probably have a special success chart or benefit of some type. Basically the double damage on impales made the condensed damage vales a nightmare. TO make something proof against a 5.56 round, I'd need 32 points of armor, putting it beyond the ability of a .60 cal to penetrate without an impale.

As it is, I ignored that the armor was aluminum just to get decent values.

aha....ok. Nonetheless I think that an 10t APC with only a few AP more than the max protection of a medieval plate armor is odd.

Me too. by BRP seems to follow a quadruple the thickness, double the AP rule. If 2" of steel plate has 19AP in CoC, then I can't have 1.5 inches of aluminum with a higher AP value. Oh, if it helps, I was thinking that modern firearms would punch through most medieval armors, so roughly count the APs as half, or subtract 5 or so. I can't see medieval plate stopping a 9mm or .357 round. So 8 point plate was only worth 4 or 5 points would the APC look better?

As far as I can reverse engineer, the formula for APs in BRP is

Armor Value: Square root of thickness (in millimeters) x type factor

Type Factor

Metal (steel) 2.7

Concrete 0.75

Hardwood 0.50

It is the condensed curve the BRP uses that keeps the AP low. Realistically the APC would have about 50 times the AP of medieval plate armor for 400 AP, but BRP doesn't use a linear scale for damage so it has to compress the damage values for weapons to keep them in line. Actually I think it was done the other way around. That is, in order to keep the weapon damages in the ranges that they wanted, the had to scale down the APs to match.

A .50 cal has 47 times the energy 466 times the momentum, and around 9 times the penetrating power of a .45 ACP, but only does twice the damage in BRP. That is a pretty tight curve. Doesn't leave much wiggle room.

Maybe for a civilian car from 1920 SIZ/2 probably would fit, (and I think that the CoC values had such cars in mind) but a modern military vehicle should have a different basic formula than SIZ/2. Eg. for modern military vehicles I would assume double SIZ as HP, for modern civilian vehicles normal SIZ and only for ancient vehicles like 1920 cars or horse coaches SIZ/2.

The do give HP for modern cars like a Taurus too. I'll admit the HP values are tough, since they seem the mix SIZ and other factors. I tired messing with a CON/Durability score for vehicles, but wound up needing negative value to get some CoC values to work out.

I sort of want to try and make this as compatible as possible with the other BRP products so that it will be useful.

Personally, I favor doing it by mass, which probably means SIZ in BRP terms. Since x2 mass is +8 SIZ in BRP (through most of the charts), that sort of limits things.

The problem with double SIZ as hit points it that we have tanks with 180 hit pints, behind 70 point armor in a game where a 120mm AP round is doing around 20D6 damage. Since most of the mass IS the armor, then I think the APs should be higher than the HP, otherwise you are counting the Armor twice.

For instance if a M1A2 tank masses 65 tons, but 40tons of that is armor, thenit is really a 20 ton (SIZ77) vehicle with 70 APs or armor (more against HEAT). So AP70/HP45 looked good.

Nightshade has beens suggesting full SIZ for HP, maybe that might be a good option for miltary vehicles.

But most of this is fitting in with the values given for weapons and armors in CoC. If the BRP book changes those values, then the math changes. BUt I'm really trying to plug in numbers that fit the valeus give in CoC.

If we went with some older weapon damages, like the 1d8 for 9mm in CoC 1st edition, and the 3d6+6 for the .30 cal, I'd have a LOT more room to work in.

Chaos stalks my world, but she's a big girl and can take of herself.

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Ah. Yeah, we pretty much decided to dump impales as such, but will probably have a special success chart or benefit of some type. Basically the double damage on impales made the condensed damage vales a nightmare. TO make something proof against a 5.56 round, I'd need 32 points of armor, putting it beyond the ability of a .60 cal to penetrate without an impale.

good idea. Especially the special success chart. (but also some extra work)

Me too. by BRP seems to follow a quadruple the thickness, double the AP rule. If 2" of steel plate has 19AP in CoC, then I can't have 1.5 inches of aluminum with a higher AP value. Oh, if it helps, I was thinking that modern firearms would punch through most medieval armors, so roughly count the APs as half, or subtract 5 or so. I can't see medieval plate stopping a 9mm or .357 round. So 8 point plate was only worth 4 or 5 points would the APC look better?

Yes of course. But in this case, you should consider to introduce "tech levels" like Gurps and splitting the equipment to different "eras". So a modern era 8 AP armor would be effectively 16 AP vs. lower techs like medieval era crossbows. And vice versa a medieval armor has only half value against modern weapons.

As far as I can reverse engineer, the formula for APs in BRP is

Armor Value: Square root of thickness (in millimeters) x type factor

Type Factor

Metal (steel) 2.7

Concrete 0.75

Hardwood 0.50

It is the condensed curve the BRP uses that keeps the AP low. Realistically the APC would have about 50 times the AP of medieval plate armor for 400 AP, but BRP doesn't use a linear scale for damage so it has to compress the damage values for weapons to keep them in line. Actually I think it was done the other way around. That is, in order to keep the weapon damages in the ranges that they wanted, the had to scale down the APs to match.

The problem with double SIZ as hit points it that we have tanks with 180 hit pints, behind 70 point armor in a game where a 120mm AP round is doing around 20D6 damage. Since most of the mass IS the armor, then I think the APs should be higher than the HP, otherwise you are counting the Armor twice.

For instance if a M1A2 tank masses 65 tons, but 40tons of that is armor, thenit is really a 20 ton (SIZ77) vehicle with 70 APs or armor (more against HEAT). So AP70/HP45 looked good.

This would be definately the way to go. In this case I agree to your construction and will use it in my games. (if you allow :))

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I've got a second formula that also seems to fit the data points given in CoC. It uses a cube function rather than a square root.

AP=Cube root (mm)

Steel x5.14

Concrete x1.69

Hardwood: x1

Both the square a cube root formulas have advantages. The cube one seems to fit the required thickness for submarine hulls better. Or I might just use the sub formula for APs.

That is AP= Cube Root (mm*100)

Steel x1

Concrete x0.35

Hardwood: x0.20

I'm also playing around with a few more HP options. I'm trying to fit the values in CoC better. Either a tech era factor and/or factoring in the size of the Engine (something like +5 HP/cubic liter in the 1920s, and about 10HP/cubic liter c.2000, or maybe just uses the Engine L as the base for the Engine HPs. ).

One thing I wondering is if we need total Hit points for a vehicle. Unlike a person, a vehicle doesn't "bleed to death" and unless some vital is taken out, it will continue along. Shooting out the lights or tires doesn't have the same effect as shooting a man in the eyes or feet. If we just limited total HP to whole area attacks like explosions or driving off cliffs, then the vehicles would be pretty tough indeed, only stopping after their engine, proplsion or controls got shot out.

My goal is to get it so someone can take a real vehicle plug the stats into a couple of formulas and get BRP game values that are reasonable enough for game play. I'm nearly there with a rough draft. Not surprisingly Tank and Battleships with their heavy armor are the big sticking points. The armor sets the damage range for the big guns, in turn setting the scale for the weapons in between. I figure that if I can get a Kawasaki, Ford Escort, Ferrari, M113, M1A2 and Iowa-class Battleship to work out then the ratings should hold up for anything in between.

Chaos stalks my world, but she's a big girl and can take of herself.

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