Air Jet damage

[Plane]

Originally Posted by kirbwarrior

If you stabbed someone with a spear for 8 damage who was wearing DR9 plate, I think the spear isn't hitting squarely enough to move them because part of how the armor works is precisely to stop hits from hitting squarely.

I agree with how a lot of surfaces work, although it might depend on the armor... flexible armor for example seems like it'd be more apt to "hug" a spearhead and have it not merely deflect off too the side (especially tip-catchers like chainmail) although perhaps the flexible armor itself would more aside (get dragged around) almost like a grapple?

When I look at https://www.youtube.com/watch?v=Yr4K28Kl8hg when the guy gets hit with the spear, although it's certainly a major wound where he's going to suffer knockdown and fall off his horse regardless, the complete lack of delay (he just gets LAUNCHED off) definitely seems like knockback to me.

The idea that DR has to stop cutting damage to stop knockback doesn't really make a lot of sense to me. If anything, I would think that the only thing that might lessen knockback from cutting is completely slicing through something, in which case whatever knockback you'd get from the unused damage would be lost.

That's what I'd expect with impaling too. The transfer used to actually do injury should always transfer momentum but once it overpenetraes, any extra damage wouldn't do knockback except to foes behind you it hits.

This is one case where back armor would make a difference: if a spear penetrates the front of a breast plate and the entire torso HP but is stopped by the back plate's DR then all the max knockback could happen.

Even with piercing damage: if we think of the whole "shoot tin cans as target practice" the cans DO get knocked back: https://www.youtube.com/watch?v=c5DqZ5VM1VU

You can see people actually put a wall behind the can to stop them from falling off but sometimes if you hit them high they flip over anyway.

I'm thinking maybe we should just use similar rules as Blunt Force Trauma (B372) for Knockback: cutting/impaling/piercing is just half as good as crushing. So instead of ST-2 to get a yard, you'd need ST*2-4 (minimum 2 damage)

Using B104's "Double Blunt Trauma" we could even extend that to more types: make Burning/Corrosion half as good as Cut/Impale/Pierce (so 1/4 as good as crushing) so you'd need to inflict ST*4-8 (minimum 4 damage) to knock something back a yard.

That sounds pretty reasonable, fire/acid can have SOME mass/impact.

This way the only thing lacking it would be Fatigue Attack.

[kirbwarrior]

Originally Posted by Plane

I agree with how a lot of surfaces work, although it might depend on the armor... flexible armor for example seems like it'd be more apt to "hug" a spearhead and have it not merely deflect off too the side (especially tip-catchers like chainmail) although perhaps the flexible armor itself would more aside (get dragged around) almost like a grapple?

When I look at https://www.youtube.com/watch?v=Yr4K28Kl8hg when the guy gets hit with the spear, although it's certainly a major wound where he's going to suffer knockdown and fall off his horse regardless, the complete lack of delay (he just gets LAUNCHED off) definitely seems like knockback to me.

The main thing I'm noticing from that is the guy is utterly dead. I think that's very important. And probably unrealistic, enough damage that can kill someone with a spear in GURPS is also the minimum for Overpenetration (-HP to hit kill damage, but basic damage equal to HP is max damage the spear can do). Thinking back to the 'arrows can't deal knockback' and translating that to much stronger people throwing spear at each other, I think the knockback would be too little to notice if it exists.

Imp and pi doing 1/4 knockback seems fine, but I think the important thing is the weapon has to, in some way, 'catch' onto someone to pull them back. And considering that (usually) 1 yard of knockback is similar in damage to nearly kill knock someone out with crushing, I'm not sure if it's too important to have to worry about knockback with these damage types since the GM can just rule something for corpses.

I guess it would matter for characters with giant HP above mass or Damage Divisors. But anything with enough DR to stop damage from impaling likely isn't moving far from getting hit by it. There is still force being applies, but knockback is a tremendous amount of force.

As for Burning and Corrosion, I'm not sure if those would make sense. Attacks where it seems to move things might just be linked with Crushing in some way.

[Rolando]

The problem I see is when you consider supers, battlesuits or others cases with very high DR and probably not very high mass nor ST.

This is of course a somewhat simplified rule and must be treated as such.

If there is super tech, magic or other special cases maybe impaling and piercing damage can cause knock back (at the GM discretion).

Then there is a case for weapon mass, a spear (backed by a soldier) and an arrow may both do 1d+3 damage but I doubt both will have the same knock back effect on a target.

For most "normal" cases impaling attacks will pierce and get embedded, go trough or simply not be strong enough to cause knock back.

[Plane]

Originally Posted by kirbwarrior

The main thing I'm noticing from that is the guy is utterly dead. I think that's very important. And probably unrealistic, enough damage that can kill someone with a spear in GURPS is also the minimum for Overpenetration (-HP to hit kill damage, but basic damage equal to HP is max damage the spear can do).

Ah: but he would take fall damage, maybe that's what finished him off?

I can't say for sure it was 'dead before he hit the ground'.

Plus are we 100% sure he wasn't just stunned (failed HT check from major wound) and then died a few seconds later from blood loss?

[kirbwarrior]

Originally Posted by Rolando

If there is super tech, magic or other special cases maybe impaling and piercing damage can cause knock back (at the GM discretion).

I'm all for an enhancement for impaling and piercing (and even cutting) attacks that gives them the ability to do knockback as per crushing. For instance, a spear could have a 'clawed' head that embeds into the target, giving it Armor Divisor 1/2 and Knockback. It would make for quite the scary looking weapon and be good for mob control.

Originally Posted by Plane

Ah: but he would take fall damage, maybe that's what finished him off?

I can't say for sure it was 'dead before he hit the ground'.

Plus are we 100% sure he wasn't just stunned (failed HT check from major wound) and then died a few seconds later from blood loss?

To be fair, we are looking at a movie that intentionally is cinematic instead of realistic. And I do like the idea of 'if the attack kills them, apply full knockback as per crushing' as a fun cinematic rule of cool.

[Gold & Appel Inc]

The scene from Troy pretty clearly shows the spear sticking out of the guy's throat in the close-up of him on the ground, so the armor he's wearing is irrelevant and neither the impact nor the fall killed him - Coughing up most of his blood did.

[Plane]

Originally Posted by kirbwarrior

To be fair, we are looking at a movie that intentionally is cinematic instead of realistic. And I do like the idea of 'if the attack kills them, apply full knockback as per crushing' as a fun cinematic rule of cool.

Ignoring impaling: where it only applies to cutting blocked by DR just really doesn't make sense at all.

Although I guess using LT's rule (cutting converts to crushing unless it beats DOUBLE the DR) this expands the capability of cutting attacks to inflict knockback even when surpassing DR.

I still don't like the idea that actually getting cutting multipliers on injury means no knockback though. I'd rather it just be REDUCED knockback like with blunt trauma (2 cutting = 1 crushing) which reflects that some force is going sideways (ripping the tissue open) but SOME of it is still going forward.

Plus obviously you lose excess damage (for calculating knockback included) if you completely cripple a limb.

You could give knockback to impaling using a similar principle.

[kirbwarrior]

Originally Posted by Plane

Ignoring impaling: where it only applies to cutting blocked by DR just really doesn't make sense at all.

Although I guess using LT's rule (cutting converts to crushing unless it beats DOUBLE the DR) this expands the capability of cutting attacks to inflict knockback even when surpassing DR.

I still don't like the idea that actually getting cutting multipliers on injury means no knockback though. I'd rather it just be REDUCED knockback like with blunt trauma (2 cutting = 1 crushing) which reflects that some force is going sideways (ripping the tissue open) but SOME of it is still going forward.

Cutting actually makes a lot of sense to me. The force is no longer applying in the direction of impact but perpendicular to it. Unless the blade is extremely thin (which usually undermines cutting weapons) the angle would push the parts apart from each other. This amount is pretty minor normally (it's likely rolled into the reason for the cutting multiplier) but with a strong enough attack you'd likely apply half knockback to the two halves of your target.

I'm also not entirely certain it makes sense for cutting weapons to have knockback normally. A mace knocking someone over makes sense. A sword that doesn't hurt them would likely just slide. An axe might knock them over, and again I feel like it might be a weapon that has the 'Knockback' enhancement on it.

I guess a big thing to me is that a crushing attack does damage by giving a big enough impact that has the side effect of moving something. Cutting, Impaling, and Piercing deal damage by ripping something apart in some manner. Equal damage from a bullet and a rock just affect targets so significantly different.

[Plane]

Originally Posted by kirbwarrior

Cutting actually makes a lot of sense to me. The force is no longer applying in the direction of impact but perpendicular to it. Unless the blade is extremely thin (which usually undermines cutting weapons) the angle would push the parts apart from each other. This amount is pretty minor normally (it's likely rolled into the reason for the cutting multiplier) but with a strong enough attack you'd likely apply half knockback to the two halves of your target.

I'm also not entirely certain it makes sense for cutting weapons to have knockback normally. A mace knocking someone over makes sense. A sword that doesn't hurt them would likely just slide. An axe might knock them over, and again I feel like it might be a weapon that has the 'Knockback' enhancement on it.

I guess a big thing to me is that a crushing attack does damage by giving a big enough impact that has the side effect of moving something. Cutting, Impaling, and Piercing deal damage by ripping something apart in some manner. Equal damage from a bullet and a rock just affect targets so significantly different.

I'm not arguing for 'normal' knockback, but 'half knockback' basically. Instead of needing 8 damage to knock back ST 10 guy 1 yard you'd need 16 cutting.

Another issue is the concept of penetrating the front DR with cutting, but then getting stopped by the back DR.

If you don't penetrate the back DR then it should do knockback even though you also did HP by penetrating the front DR...

and if stopping short of cutting through the back DR causes knockback, why not also stopping short of cutting through all the HP?

The force is not purely "spread that flesh", but that's a LOSS of force, so it makes sense to halve it...

Or maybe rather than halving ALL of it, just apply half any HP you deplete beyond DR, up to the point of overpenetration, at which point it's either completely lost (comes out the other side) or 100% knockback due to getting stopped by back DR