Quick Sciency Karate Question

[Blood Legend]

How many dice of damage should a punch delivering about 1000 pounds of impact force, or a kick delivering 1500 impact pounds of force do?

We're having an issue in our group where the punch~smith needs more damage, but we don't want to push the limits past real-world limitations and we all know that ST damage is supposedly already really high compared to gun damage.

[Dalren]

According to this article, 1000 lbs of impact force is about the same force as that of a sledgehammer. Here's the Sledgehammer entry from High Tech:

Originally Posted by High Tech p. 25

Sledgehammer (TL5). A two-handed hammer for driving
posts, rock drills (p. 26), and so on. Treat as a maul
(p. B274) at -2 to skill. $10, 15 lbs. LC4.

According to Characters, the damage for a Maul is Swing+4 crushing. What we don't know is the ST of the person swinging the Maul. However, Characters says that ST (even for normal humans) can exceed 20. If we assume on the low side, a Maul swung by someone with ST 20 would do 3d+6 damage then that should give a reasonable starting point for a highly trained, high strength fighter. Of course, getting a similar damage out of an unarmed attack (assuming we're not using Innate Attacks) would require Karate at DX+1 and ST 29 or Brawling at DX+2 (plus an appropriate fist load) at ST 33.

[zoncxs]

Well, the boxer that they used to record that record is at least 2 to 3 times as strong as the average person. He is also well trained in his style. With that in mind.

Boxing skill at DX+2 for max bonus.

ST score of around 14-18.

That gives us:

1d+2 - 1d+4

Thrown as a committed attack strong Or aoa strong:

1d+3 - 1d+4 or 1d+4 - 1d+6

[Anaraxes]

People can put about as much energy into a punch as there is in many handgun bullets. Momentum and energy transfer mechanics are really different, so it seems hard to me to compare. You could take the Douglas Cole spreadsheet and try to treat as fist as a pi+++++ round of appropriate energy, but I'm not sure that's really any better than the RAW you already have.

[Anthony]

Originally Posted by Blood Legend

How many dice of damage should a punch delivering about 1000 pounds of impact force, or a kick delivering 1500 impact pounds of force do?

That's a nearly meaningless question, because the pounds of force delivered by a strike depend on how quickly the fist decelerates on impact -- if you have a punch with a total of 20 ft-lb energy (which is nothing special) and your first comes to a stop in 1/4", average force during the deceleration process is 960 lb (20 ft-lb, stop distance 1/48 of a foot, so force = 20 * 48) and peak is probably well over that. If you punch something more yielding, force is lower.

Punch energy is probably a better measure, but I'm having trouble finding a credible value, the estimates I'm finding vary by an order of magnitude (the true value is probably somewhere between 100J and 1,000J). The range of pistol bullet energies is from about 100J for a .22 short to about 1,500J for .44 magnum, with .45 and 9mm (2d pi+, 2d+2 pi) in the 500-700J range; depending on the energy estimates you accept, proper damage is likely somewhere between 1d and 3d.

Unfortunately, bullets apply force in a very small area, and punches don't. Bullets are also made of metal; fists are not. The combined effect is that punches should do significantly lower damage at the same energy levels, with a very poor armor divisor -- say, 1d+2(0.5) for the high end energy estimates.

[ErhnamDJ]

What Anthony said is right. Check out this video.

A lot of the energy gets lost wobbling there. In a punch the energy would get transferred back into the arm. The same thing happens with stuff like baseball bats or sticks. The energy doesn't all go into the target. The human body is probably just about the worst weapon anyone would ever seriously consider using.

I don't know how it could possibly be that your punch could exceed Joules equal to more than thrice Basic Lift. If you could punch that hard, then why is there no way to transfer that much energy into a spring such as a bow? And that's before you get into things like looking at how much of the time in that second is spent moving around dodging and parrying, or even doing multiple attacks. If you could use a single arm to do an attack with Joules equal to 3x BL three times per second (Rapid Strike + AoA (Double), then that is way, way better than you could hope to put into a bow (or to throw using the throwing rules).

It's well known that the melee damage in GURPS does not match what could be accomplished in reality. That's one part of the system where the assumption built into the rules is that of the cinematic Hollywood (or Hong Kong) movie.

You could do something like say that the punch has Joules equal to x1.5 BL (probably on the higher end, really, when you consider what all else a GURPS combatant can do in a single second) and that it's so incredibly inefficient that it's only able to transfer half of that (just making this part up) to the target, and that it's so bad at penetrating armor that it has a .25 armor divisor. And that would be more realistic than what we have now. But if you didn't also touch the melee weapons, then you'd be nerfing the unarmed combatants for essentially no reason. If you're going to use the super cinematic Hollywood movie damage for some, then it probably makes the most sense to use it for all.

[Johnny Angel]

I remember a Stan Lee's Superhumans episode in which a monk was able to generate force equal to a car crash. Though, I believe it took him some time to concentrate before doing so.


edit: I looked it up; his name is Shi Yan Ming.

[DouglasCole]

Originally Posted by ErhnamDJ

I don't know how it could possibly be that your punch could exceed Joules equal to more than thrice Basic Lift. If you could punch that hard, then why is there no way to transfer that much energy into a spring such as a bow?

Just to level-set, a 70# compound bow shooting at around 300fps can deliver about 130J, which is about 5xBL for ST 12. That's about 75% efficient using a carbon fiber target arrow.

[Anthony]

Originally Posted by ErhnamDJ

I don't know how it could possibly be that your punch could exceed Joules equal to more than thrice Basic Lift.

If we assume a force of (BL) over a distance of 3', total energy in joules is (BL*4.448 N/lb*3*0.3048m/ft) or BL*4 J/lb. However, the actual maximum force which can be applied is probably somewhat higher; if we limit it to BL*3, we get BL*12 J/lb.

High energy figures for punches probably come from a whiplash effect, where you generate rotational energy in the torso (using leg muscles) and then transfer it out to the limbs. This doesn't translate into anything you can use for a bow. Slams and tackles can routinely exceed 1 kJ.

[ErhnamDJ]

Originally Posted by DouglasCole

Just to level-set, a 70# compound bow shooting at around 300fps can deliver about 130J, which is about 5xBL for ST 12. That's about 75% efficient using a carbon fiber target arrow.

Yeah, but that's using both hands (which karate punches don't do) and, even more importantly, that's storing the energy in the spring over multiple seconds.

The stored energy there is 177J, but that's over two seconds and two arms. GURPS assumes that both arms are equally strong, so that's around 44 Watts per arm. For a ST 12 guy, that's less than twice his Basic Lift.

If you look at someone strong enough to draw the bow in one second (someone with ST 14 and a BL of 39), then that's still only a little bit more than twice his BL in Joules per arm.

And doing a Ready only allows a single step. A karateka might be throwing two or three attacks in a single second and doing the same number of parries, while moving his whole move at the same time on a Move and Attack.