DR derivation in GURPS?

Talonos · 09-09-2014, 06:01 PM

If you want to know how much damage something does, look at the joules of force it delivers, and make the damage type dependent on the size of the entry wound. The math is available if you really care.

If you want to know how much DR something has, you... what?

Common materials are in the back of the campaign book, and you can extrapolate. But let's say you have an unconventional material that you know a lot about in real life, but want to convert to GURPS?

How did the authors of GURPS decide on the DR of materials in low-tech, for instance?

Thanks. I appreciate how consistently helpful and friendly these forums are.

Nereidalbel · 09-09-2014, 06:10 PM

If you're thinking of using it as armor, it's a terrible plan. Diamond has this little fragility issue, where any attack at the right angle will shatter it. In GURPS terms, I guess you could say a critical hit strikes that angle.

As for the DR calculations, I'm not sure where to point you on that one. Sorry.

gilbertocarlos · 09-09-2014, 06:22 PM

Diamond is very hard(and brittle), so, it's semi ablative, apart from that it's very expensive.

I'd use LT stone armor as a baseline, but with higher DR, and an over the top CF.

Fred Brackin · 09-09-2014, 06:23 PM

Quote:

Originally Posted by Talonos

If you want to know how much damage something does, look at the joules of force it delivers, and make the damage type dependent on the size of the entry wound. The math is available if you really care.

If you want to know how much DR something has, you... what?

If it's actually used as armor in the real world currently you can probably find either it's equivalence to mm of RHA (DR70/inch) or a NIJ level x standard used in bulletproof vests. Then you find what sort of ammo that level vest stops which gives you a D of damage.

If you're looking at futuristic sort of armor there are various sources in Gurps publications. Diamond really wouldn't make practical armor but a composite synthetic diamond/nanocarbon material called "diamonded" is seen in several places. Gurps Spaceships makes it TL11 and about 7x as effective as Steel.

That is per unit of weight and not thickness. It'd be (roughly) around half that per unit of thickness.

Anthony · 09-09-2014, 06:59 PM

The calculations from energy to damage are at best a rough approximation. Fundamentally, damage in GURPS is based on penetration of (idealized) RHA, DR is based on RHA equivalent. Both figures are significantly dubious, as not all armors behave identically to RHA and thus they have different relative performances against different attacks.

Talonos · 09-09-2014, 07:24 PM

Interesting. That gives me something to look at... I was never familiar with "RHA" before. Thanks for the terminology.

sir_pudding · 09-09-2014, 07:41 PM

Quote:

Originally Posted by Nereidalbel

Diamond has this little fragility issue, where any attack at the right angle will shatter it.

Also flammable.

Anthony · 09-09-2014, 08:12 PM

Quote:

Originally Posted by sir_pudding

Also flammable.

While technically true, unlikely to be a factor most of the time; a large solid chunk of diamond would be tough to ignite.

sir_pudding · 09-09-2014, 09:15 PM

Quote:

Originally Posted by Anthony

While technically true, unlikely to be a factor most of the time; a large solid chunk of diamond would be tough to ignite.

Diamond ignites at 850 to 1000 C. Napalm burns at about 800-1200 C. So flamethrowers should do it.

DouglasCole · 09-09-2014, 09:17 PM

Quote:

Originally Posted by sir_pudding

Diamond ignites at 850 to 1000 C. Napalm burns at about 800-1200 C. So flamethrowers should do it.

Someone call Mythbusters and a jilted fiancee...

09-09-2014, 06:01 PM	#1
Talonos Join Date: Jan 2007	DR derivation in GURPS? If you want to know how much damage something does, look at the joules of force it delivers, and make the damage type dependent on the size of the entry wound. The math is available if you really care. If you want to know how much DR something has, you... what? Common materials are in the back of the campaign book, and you can extrapolate. But let's say you have an unconventional material that you know a lot about in real life, but want to convert to GURPS? How did the authors of GURPS decide on the DR of materials in low-tech, for instance? Thanks. I appreciate how consistently helpful and friendly these forums are.

09-09-2014, 06:10 PM	#2
Nereidalbel Join Date: May 2013 Location: Ellicott City, MD	Re: DR derivation in GURPS? If you're thinking of using it as armor, it's a terrible plan. Diamond has this little fragility issue, where any attack at the right angle will shatter it. In GURPS terms, I guess you could say a critical hit strikes that angle. As for the DR calculations, I'm not sure where to point you on that one. Sorry.

09-09-2014, 06:22 PM	#3
gilbertocarlos Join Date: Dec 2009 Location: Caxias do Sul, Brazil	Re: DR derivation in GURPS? Diamond is very hard(and brittle), so, it's semi ablative, apart from that it's very expensive. I'd use LT stone armor as a baseline, but with higher DR, and an over the top CF. __________________ I've revised the Low Tech weapons table: http://forums.sjgames.com/showthread.php?t=112532

09-09-2014, 06:59 PM	#5
Anthony Join Date: Feb 2005 Location: Berkeley, CA	Re: DR derivation in GURPS? The calculations from energy to damage are at best a rough approximation. Fundamentally, damage in GURPS is based on penetration of (idealized) RHA, DR is based on RHA equivalent. Both figures are significantly dubious, as not all armors behave identically to RHA and thus they have different relative performances against different attacks. __________________ My GURPS site and Blog.

09-09-2014, 07:24 PM	#6
Talonos Join Date: Jan 2007	Re: DR derivation in GURPS? Interesting. That gives me something to look at... I was never familiar with "RHA" before. Thanks for the terminology.