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Old 05-18-2013, 06:41 PM   #31
Green-Neck
 
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Default Re: Skull and Spine DR - shouldn't these scale?

I thought I might resurrect this thread rather than start a new one.

I've been pondering DR and skulls, especially for animals like elephants.
It seems the generic DR 2 for all skulls is a little granular for me.
Personally I believe size modifier is a better indicator of skull DR than HP and I'm happy that all humans should be generically DR 2.
However having read about the experiences of professional hunters in Africa, a .375 (8d) is considered the minimum to penetrate an elephant skull most of the time, and a .416 Rigby (10d+1) to reliably penetrate it.
If the .375 averages 28 damage, the skull DR must be a large portion of that.
Some hunters used to target 'chinks in armour' for the perfect brain shot and get away with high power 6.5 and 7mm cartridges (21 damage, but half the DR).


A problem arising is it seems to me that if you can get 2-3 dice worth of damage into the brain pan it's game over for any creature walking this earth. But the elephant has 45 HP, so you need to do HPx2 ( to get to -1x base HP) /4 =22.5 points of basic damage to have a chance of killing an elephant with a brain shot.

Obviously larger creatures brain sizes do not increase in size in a linear way. Elephants have smaller brains than humans, and whales less than twice as big as humans.
It looks like the game designers have used HP rather than DR to model killing larger creatures with head shots.

Doesn't quite feel like it passes the reality check for me - any ideas how to remedy this situation?
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Last edited by Green-Neck; 05-18-2013 at 06:45 PM.
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Old 05-18-2013, 07:03 PM   #32
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Default Re: Skull and Spine DR - shouldn't these scale?

Quote:
Originally Posted by Green-Neck View Post
I thought I might resurrect this thread rather than start a new one.

I've been pondering DR and skulls, especially for animals like elephants.
It seems the generic DR 2 for all skulls is a little granular for me.
Personally I believe size modifier is a better indicator of skull DR than HP and I'm happy that all humans should be generically DR 2.
However having read about the experiences of professional hunters in Africa, a .375 (8d) is considered the minimum to penetrate an elephant skull most of the time, and a .416 Rigby (10d+1) to reliably penetrate it.
If the .375 averages 28 damage, the skull DR must be a large portion of that.
Some hunters used to target 'chinks in armour' for the perfect brain shot and get away with high power 6.5 and 7mm cartridges (21 damage, but half the DR).


A problem arising is it seems to me that if you can get 2-3 dice worth of damage into the brain pan it's game over for any creature walking this earth. But the elephant has 45 HP, so you need to do HPx2 ( to get to -1x base HP) /4 =22.5 points of basic damage to have a chance of killing an elephant with a brain shot.

Obviously larger creatures brain sizes do not increase in size in a linear way. Elephants have smaller brains than humans, and whales less than twice as big as humans.
It looks like the game designers have used HP rather than DR to model killing larger creatures with head shots.

Doesn't quite feel like it passes the reality check for me - any ideas how to remedy this situation?
Well, DR 2 human skull vs HP 10.

Let's play, and extrapolate.

DR 9 elephant skull vs HP 45?

Brain shot for DR 9 (2d+2) and need 22.5 pts (about 6d+1) to on the average go from HP to -HP. Total of about 9d, or a bit less.

That straddles it pretty well. With "aim for chinks" knocking this down to 7d+2; I have a 7mm Remington Magnum at about 8d with a 165gr bullet at 900m/s.

This all tracks well with your assumptions, and suggests HP/5 works within the realm of "not dumb" for humans and elephants.
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Old 05-18-2013, 07:04 PM   #33
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Default Re: Skull and Spine DR - shouldn't these scale?

One solution (it does add complexity however) would be to cap damage needed for skull damage death checks to -1xbase HP, or -1x10 HP, which ever is the lesser.

Given the delicate nature of brain tissue, and the lack of very large brains in nature, this would both give a more realistic brain-shot mechanics, and allow for a realistic amount of DR to protect the brain.

My instinct for increasing DR by size would be to follow the Fibonacci sequence, which is reasonably easy to remember if you like numbers at all. Peg SM0 at DR 2 as per RAW.

Code:
SM <<-3   DR0
SM -2     DR1    
SM -1     DR1
SM 0      DR2
SM 1      DR3
SM 2      DR5
SM 3      DR8
SM 4      DR13
SM 5      DR21
SM 6      DR34
Allow perk/quirk:
Tough Skull: +1 SM for calculating skull DR, suitable for animals that commonly use head butting.
Thin Skull: -1 SM for calculating skull DR, suitable for animals that are gracile in form.

So a SM3 elephant (female) would have 8 skull DR, but an adult bull would qualify for Tough Skull and have DR 13.

I'm not sure if my DR numbers are high enough, but they (to me) have a nice progression curve.
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Old 05-18-2013, 07:48 PM   #34
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Default Re: Skull and Spine DR - shouldn't these scale?

Quote:
Originally Posted by DouglasCole View Post
Well, DR 2 human skull vs HP 10.

Let's play, and extrapolate.

DR 9 elephant skull vs HP 45?

Brain shot for DR 9 (2d+2) and need 22.5 pts (about 6d+1) to on the average go from HP to -HP. Total of about 9d, or a bit less.

That straddles it pretty well. With "aim for chinks" knocking this down to 7d+2; I have a 7mm Remington Magnum at about 8d with a 165gr bullet at 900m/s.

This all tracks well with your assumptions, and suggests HP/5 works within the realm of "not dumb" for humans and elephants.
OK that mechanic is easy to remember and gives more realistic skulls for larger creatures - it does leave humans the ability to get DR 3-4 though, which is starting to sound like too much to me.

The problem is when creatures are larger than human scale their brains effectively become enormous in gurps. The system is modelling a thin DR2 skull wall with a massive brain that takes 6-7d of damage to have a 25.9% chance of killing the elephant.
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Old 05-18-2013, 08:27 PM   #35
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Default Re: Skull and Spine DR - shouldn't these scale?

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OK that mechanic is easy to remember and gives more realistic skulls for larger creatures - it does leave humans the ability to get DR 3-4 though, which is starting to sound like too much to me.
Use racial average HP?

Quote:
The problem is when creatures are larger than human scale their brains effectively become enormous in gurps. The system is modelling a thin DR2 skull wall with a massive brain that takes 6-7d of damage to have a 25.9% chance of killing the elephant.
Scale DOWN the brain? Maybe it's a SM smaller?

http://faculty.washington.edu/chudler/facts.html

This suggests the elephant brain is 3.5x the mass of the human brain; cube root of that is 1.5x human size, perhaps. That's a SM+1 brain on an SM+3 creature.

If you call it like that, you might give the brain half the HP (two SM's smaller), making it typically about 22 HP for a 45 HP elephant.
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Old 05-18-2013, 09:14 PM   #36
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Default Re: Skull and Spine DR - shouldn't these scale?

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Use racial average HP?


Scale DOWN the brain? Maybe it's a SM smaller?

http://faculty.washington.edu/chudler/facts.html

This suggests the elephant brain is 3.5x the mass of the human brain; cube root of that is 1.5x human size, perhaps. That's a SM+1 brain on an SM+3 creature.

If you call it like that, you might give the brain half the HP (two SM's smaller), making it typically about 22 HP for a 45 HP elephant.
I think 22 HP sounds about right - when you apply the aforementioned firearms, a penetrating damage of 3d+1 for 25% kill sounds in the ballpark.
That leaves about 5d of armour for the iffy .375 to be just doing the job. The .416 Rigby will be doing 5d+1 to the brain for two death checks.

So - we need to have a scaling up from DR2 SM0 to DR17.5(5d) SM3 to reality check with the PH's experiences. That's double the 1/5 HP/DR idea.

Also - how do we make a brain-size rule generic enough to not require doing research into an animals brain size to stat it?
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Old 05-18-2013, 09:42 PM   #37
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Default Re: Skull and Spine DR - shouldn't these scale?

Simple answer, as noted here and there:

Yes it makes perfect sense to scale skull/spine DR for SM. (It'd be strange not to do so.) Scale it with SM's linear measurement, in the same general way ST scales with SM: x1/2 for SM -2, x10 for SM+6, etc.

That's just gives suggested DR, of course. Modify to taste for individual species/creatures.
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Old 05-18-2013, 11:42 PM   #38
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Default Re: Skull and Spine DR - shouldn't these scale?

Quote:
Originally Posted by Green-Neck View Post
However having read about the experiences of professional hunters in Africa, a .375 (8d) is considered the minimum to penetrate an elephant skull most of the time, and a .416 Rigby (10d+1) to reliably penetrate it.
If the .375 averages 28 damage, the skull DR must be a large portion of that.
Some hunters used to target 'chinks in armour' for the perfect brain shot and get away with high power 6.5 and 7mm cartridges (21 damage, but half the DR).
"Professional hunter" means someone who guides wealthy tourists.

By "some hunters" you mean ivory hunters, people who made their living killing elephants. 6.5x54mm Mannlicher-Schoenauer and 7x57mm Mauser are not by any stretch of the imagination "high power".
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Old 05-19-2013, 02:03 AM   #39
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Default Re: Skull and Spine DR - shouldn't these scale?

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Originally Posted by Green-Neck View Post
One solution (it does add complexity however) would be to cap damage needed for skull damage death checks to -1xbase HP, or -1x10 HP, which ever is the lesser. [...]
One funny consequence is that deep-negative-SM creatures start alternating between high DR and negative DR.
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Old 05-19-2013, 02:20 AM   #40
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Default Re: Skull and Spine DR - shouldn't these scale?

Vicky:
How do you get to negative DR?
Using my original suggestion creatures <<SM-3 are all DR 0.
Using 1/5th of HP as Skull DR will eventually round down to DR 0.

Purple Haze:
I was using professional hunter in the original sense, that is one who hunts for a profession. Today the meaning has changed somewhat to 'hunting safari tour guide' as there is very little shooting to be done in Africa in a professional way. Well, in comparison the heyday of hunters like W.D.M.Bell, who shot 1011 elephants for ivory, mostly with a 7mm x 54.

I use the term 'high-power' rifle to denote full power battle-rifle sized chamberings, as opposed to intermediate or low power chamberings.

Tbone: can you give me a ref for the ST and size scaling?, I can't find it in the basic set... ta.
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