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Vehicle Combat: I can’t be doing this right


rleduc

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I’m hoping that I am overlooking some detail in the combat system – maybe someone here can see it and tell me what I’ve overlooked.

In the real world I drive a 1997 Accord with 230,000 miles on it. According to the book, this vehicle will have AV 10 and HP 40 – as GM I rule that the thing is down 10% of its HP due to mileage (whatever) – leaving it with HP 36.

On a particularly bad day, someone takes my car and drives over an antitank mine which goes off delivering average damage of 6D6+6 or 27 points. Now the driver takes 27-2 or 25 HP which will reduce a normal person to mush – but the car takes 27-14 or 13 points and after I wash out the interior I can drive it to work. Unfortunately, someone decides to use it for LAW Rocket target practice. Each rocket does 8D6 or, on average 28 points. My poor car was at 36-13 or 23 points when the first rocket hits doing 28-14 or 14 points – leaving the Accord at HP 9 which is still above 5, so it has no damaging effects to its performance. (If it looses another 4 HP its max speed will drop by 50%.)

Am I missing something?

Thanks,

Rich

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Since mines and LAW rockets cause explosions, I would use the Explosions

rules from the Spot Rules chapter and apply all the explosion damage as ge-

neral damage to vehicle and passengers alike.

The mine would detonate within 1 m of the car and would cause the 6d6+6

hit points damage, reducing your car to 9 hit points on average (let us not

mention the poor passenger ...).

Since your vehicle would still have more than 5 hit points, but less than half

of the hits points it started with, the Vehicle Damage rules on p. 216 / 217

would allow you to drive what remained of your vehicle at half speed, if you

wanted. Think of a vehicle that has been thrown through the air and badly

damaged by the mine blast, but is still able to crawl.

Later on the first LAW rocket would almost vaporize the wreck of the car with

28 points of damage against the remaining 9 hit points.

Well, at least this is how I would handle it. :)

Edit.:

On second thoughts, if you divide the car into hit locations, with a zone within

1 m of the mine explosion and a second zone within 1 + m from the explosion,

and give the lower zone - most probably including the engine or other vital

parts - 75 % of the weight and hit points of the car, this lower zone will take

enough damage to destroy the engine completely, I think.

Edited by rust

"Mind like parachute, function only when open."

(Charlie Chan)

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I think you've missed a couple of real world issues.

1. Anti tank mines are designed to incapacitate a tank's tracks rather than penetrate the armour. They can be triggered by pressure and can be set to ignore light vehicles.

2. Light Antitank Weapons are designed to penetrate armour and kill the crew. The explosion in the interior may cause additional damage through fire to the controls and may trigger a second explosion as the ammunition catches fire.

In both cases above the tank could be repairable depending on the dammage.

In the case of your accord. The explosion of the antitank mine would destroy your tyre, wheel, suspension, steering and possible engine and or petrol tank. Additionally the passengers in the front would suffer shrapnel from the explosion.

In the case of the LAW, the car interior would be consumed by fire after the explosion and there is a high chance that the petrol tank would also explode catch fire.

In both circumstances, although the vehicle could be repairable, one or more components would be destroyed, rendering the car useless.

See it as a Major Wound result crippling the car.

Likes to sneak around

115/420

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Since mines and LAW rockets cause explosions, I would use the Explosions

rules from the Spot Rules chapter and apply all the explosion damage as ge-

neral damage to vehicle and passengers alike.

The mine would detonate within 1 m of the car and would cause the 6d6+6

hit points damage, reducing your car to 9 hit points on average (let us not

mention the poor passenger ...).

I’m with you up to here – 6D6+6 will average 27 points – more then enough to toast the driver, but with 14 AV on the car, it is only going to take 13 points – hardly more then a fender bender.

Since your vehicle would still have more than 5 hit points, but less than half

of the hits points it started with, the Vehicle Damage rules on p. 216 / 217

would allow you to drive what remained of your vehicle at half speed, if you

wanted. Think of a vehicle that has been thrown through the air and badly

damaged by the mine blast, but is still able to crawl.

There we go – I had miss remembered those rules. Half damage for half movement and the vehicle stops at 5 HP – still given the armor, the mine would not have even dropped the car to half move. I looked at explosions and didn’t see anything about not counting armor – so I am still left with my initial conundrum, how can a passenger car survive an antitank mine and still drive away.

The problem seems to me to be the amount of armor given cars. Does anyone see an “unintended consequence” to simply lowering the AV of vehicles?

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I think you've missed a couple of real world issues.

1. Anti tank mines are designed to incapacitate a tank's tracks rather than penetrate the armour. They can be triggered by pressure and can be set to ignore light vehicles.

2. Light Antitank Weapons are designed to penetrate armour and kill the crew. The explosion in the interior may cause additional damage through fire to the controls and may trigger a second explosion as the ammunition catches fire.

In both cases above the tank could be repairable depending on the dammage.

In the case of your accord. The explosion of the antitank mine would destroy your tyre, wheel, suspension, steering and possible engine and or petrol tank. Additionally the passengers in the front would suffer shrapnel from the explosion.

In the case of the LAW, the car interior would be consumed by fire after the explosion and there is a high chance that the petrol tank would also explode catch fire.

In both circumstances, although the vehicle could be repairable, one or more components would be destroyed, rendering the car useless.

See it as a Major Wound result crippling the car.

Thanks for your input – in this case I am working on post-apocalyptic jalopy mechanics (as per, say, Mad Max) and I am actually trying to understand the BRP mechanics so I can develop a credible system. In game play, I would agree with your version, but I would also tend to pile additional damage on the car – the blast cutting through the engine compartment is likely to destroy vacuum lines, rupture any number of other soft components and generally disable the vehicle.

I like the idea of a major wound system for cars – it would be easy to implement and go with a fast and furious chase system.

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Hmmm ... :confused:

I think the armor value of the car protects the passengers inside the car,

but I doubt that it is meant to protect the car itself.

My understanding was that when there are two numbers, such as with the sedan that the first number applied to the car, while the second applied to the passengers.

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OK, maybe I am confused (and should look at the book when I get

home), but ...

Didn't you say that the AV is 10 and not 14? If so, 6d6+6 averages 27 HP

damage. Subtracting AV of 10, 17 HP of damage gets through. The Accord

originally had 40 HP, but you rule it only has 36 HP due to age. 36 - 17 is

19 HP left. But, this is more than 50% of the original 40 HP, so the half

speed rule applies. Additionally, in the playtest (again, I need to refer to

the book), there is an option for the GM to roll against the Chase Mishap

table any time the vehicle is damaged.

Seems that should cover it nicely.

-V

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No, unfortunately, I’ve been saying 14 – and I just double checked and that figure is correct. Therefore the car has 23 HP and is still running fine.

I think the real take home lessons here, are 1) I had made a mistake regarding how much damage a car can take before it is affected by HP loss, 2) in most cases it is easy to house-rule through the issues as they come up, and 3) there is room for adjustment with the vehicle rules as written (I think I will lower the AV on certain vehicles).

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Another thought.

The underside of commercial passenger vehicles is not very thick.

I recall an incident in high school where someone ran over a not

very thick branch which pierced the floorboards.

Also, an big complaint in Iraq was that the Humvees and trucks were

not properly armored, cost cutting led to the elimination of extra

armor underneath. The number of casualties resulting from roadside

bombs prompted a call to change that.

Maybe the vehicle rules need some "armor location" rules as well :)

What are some other vehicle AVs? How does 14 compare?

-V

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My old house rules that I am trying to BRP-ify were based loosely on the original zip-lock Car-Wars game. In that game you had six different armor locations; four sides and top and bottom. What I am hoping to do is come up with something that feels like BRP – fast and easy, not too much book keeping, while still keeping the feel of “crazy guys welding together combat cars and going at it”.

I’ll keep the board posted on how it turns out.

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In the real world an AT mine will destroy (completely) an Accord. Rather medium size IED's (10 Kg) of home made explosives will destroy a large pickup truck.

8 people (3 in front, 5 in back) hit an IED in a bongo truck (a large bed pickup style truck). The IED killed all 8 of them (shrapnel), tore the bed of the truck off in two pieces with the tailgate becoming a third large piece of shrapnel.

The IED (pressure plate) detonated under the right front tire. The right front tire and quaterpanel were gone. The engine was blown out the left side of the vehicle. The left front tire was also removed from the vehicle. The cab was seperated (at the firewall) from the engine compartment.

The rear axle had both tires still attached (flattened) but about 5 meters rear of the explosion.

The furthest large shrapnel piece travelled about fifty meters, with "most" of the large parts contained in an lozenge shape five meters by twenty meters with the point of detonation being the right hand focal point and the long axis being approximately 200-220 degrees off the line of travel of the vehicle.

So...taking the "real world" results of that 10 Kg of HME, turn that into Game Mechanics, not the other way around.

For a straight AT mine, they have a tendency to explode directly vertical (they are usually NOT straight High Explosive, but rather a "platter charge/Explosively Formed Projectile/Self Forging Warhead"). GENERALLY, the explosion is rather clean and will (vs. "wheeled vehicles") remove the wheel, the hub, and it has a tendency to take along half the axle shaft as well. about a 50% chance of whether the frame is bent. On a narrow frame vehicle, you might get lucky (the frame is less than the width of the engine)...if it's a wide frame, it will most likely be bent sharply upward, so the vehicle, even if "repaired" will still probably never drive straight again.

For a "V" hulled vehicle, the angle of incidence is usually such that the blast/projectile is deflected and thus will usually prevent penetration of the hull by the projectile. The large ground clearance also helps to dissipate blast before the blast wave impacts the vehicle hull.

For tracked vehicles, an AT mine will again detonate directly upward, and will (depending on the track material...) sever the track by blowing up 3 to 4 "track pads"...AKA track links. IF the mine detonates under a "road wheel" it will usually knock it off, which will immobilize the tank until the track is repaired (which depending on crew skill and conditions) in as little as 10 minutes (in "perfect" situation with an "expert crew") to four hours...or longer (under fire, at night, untrained crew, and poor equipment)...but on average, even under fire, 1 hour.

ummm, sorry for rambling...but AT mines vs cars...cars are usually totaled. ;-(

-STS

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I done a litle work on this with my vehicle design stuff, so here are some of my observations:

1) THe explsoion values are a bit high.In game termsonly takes about 1 lb of C-4 to give explssion damage equvalent to a 120mm HE tank round. That just isn't right.

2) Assuming the car could set off the anti-tank mine (doubtful), the damage would really go into the wheel, which would prtotect the occupants of the vehcile, but not that much. BRP armor values kind of assume that the occupants are only protected by the skin of the vehicle, as when the vehicle is shot at. In this case, I7d probably give the passengers the benefit of the higher AP rating, but it probably won't make much of a difference, since the remaining damage is probably still going to be high enough to waste everyone.

3) One thing not considered in the rules is that the vehicle is in direct constact with the charge, and that the charge is probably shapred to maximize it's effect in the exact direction the vehcile is at, in realtion to the charge. This would make the charge much more effective against the vehcile, and less effective than, say, a grenade on those not directly over the blast.

4) Part of the explosive's effectiveness on vehicles in the real world is because vehicles as so large. A vehicle that is, say 8 times the size of a man, probably get hit with 4 times the shrapnel and blast due to increased surface area. Also, the explion can trigger secondary explsoions, fires, and other damage. So a vechile that sruvives and explosion probably wouldn't survive it for long.

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

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Reading this thread reminded me of a trip to Caernarfon Castle with some RPG friends, we looked over one of the walls and Ady said "That's a 12 metre drop - we could survive jumping down in RQ, hmmm ...".

RPG rules don't always reflect real life that well.

I'd set things according to how you would like things to happen. If you feel that an Accord could run over a mine and survive the explosion then set damage accordingly, however if you feel that a mine would trash a normal car then set higher damage or set extra shrapnel damage or have the fuel tank explode.

In a Mad Max style game, cars should be better able to survive catastrophic damage as that is the whole point of the game.

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soltakss raises a good point here. Game rules generally should reflect the "reality" that why are trying to mimic. I recall a Superheroperheroish campaign I ran a few years back w. here a character fell out (well crashed though) the window of a skyscaper. Realsistically, the PC should have been dead.or at least badly messed up from the 100 meter fall. In the game the PC was just stunned for a round, and trashed the sidewalk and a water main.

Since BRP is a generic systerm, I think the way to go would be to try to make the explisive rules fairly realistic with options to "dail down" the effects as desired to reflect certain settings or styles of play. That way everyone could get what they want.

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

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1) I had made a mistake [reading the rules]
Happens to me all the time ... :o

2) in most cases it is easy to house-rule through the issues as they come up, and
Percentages by-the-seat-of-the-pants are easy ... :D

3) there is room for adjustment with the [...] rules as written
And that is why I love BRP! :thumb:

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Dreamscape Design: My Corner of BRP Central ... Mine, All Mine! 

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