Piercing damage against low tech armor

[Rupert]

Originally Posted by Varyon

I can certainly see a case made to have the WM be lower for game balance purposes, yeah. Then again, getting ~2d(2) imp from a bow probably requires comparable investment to getting ~3d+1 cut with a swung weapon, and those manage comparable wounding against the DR 7 Heavy Steel Corselet from Characters, so the former isn't necessarily broken (there is the issue you can manage this from range, of course, but you often need higher skill to reliably hit a ranged target than you do to reliably hit a melee one).

Composite Bow, ST13, and your super-bodkins, and you're good to go. 1d+3(2) imp does 1d x2 vs basic set's plate. Using LT's higher DR plate requires more points, but then we're fixing one problem made by adding something by adding something else. Easier to just not add it in the first place.

[Verjigorm]

Originally Posted by Rupert

Of course what that does is make a half-decent PC archer able to blow right through heavy plate and average a major wound for the guy inside without having to aim for the vitals or armour chinks or anything like that.

The big problem here is that the damage values for bows is just wrong. I mean, the composite bow is, what, thrust +3imp? So a ST 12 man launches an arrow with a comparable energy to a .22? Nah, that doesn't pass the smell test.

We could halve the damage of bows, and it wouldn't be too much.

[Rupert]

Originally Posted by Verjigorm

The big problem here is that the damage values for bows is just wrong. I mean, the composite bow is, what, thrust +3imp? So a ST 12 man launches an arrow with a comparable energy to a .22? Nah, that doesn't pass the smell test.

A professional baseball pitcher throws a ~145g ball at up to ~45 m/s, for ~146J of kinetic energy. That's close to the energy of 'standard' velocity .22LR rounds (and at least equal to a .22LR standard fired from a pistol). A good bow should do better than that.

This is consistent with what you'd expect from a bow of 100+ pounds drown for a couple of feet.

Oh, and I specified ST13. [/nitpick]

[Anthony]

Originally Posted by Verjigorm

The big problem here is that the damage values for bows is just wrong. I mean, the composite bow is, what, thrust +3imp? So a ST 12 man launches an arrow with a comparable energy to a .22? Nah, that doesn't pass the smell test.

Damage isn't purely a function of energy, and there's the general problem that ST damage in GURPS has a really weird curve, but a .22 isn't a terribly powerful bullet.

[Varyon]

Originally Posted by Anthony

Eh, that grossly overestimates the relevance of hardened steel for arrows. In general the reason for hardened projectiles is so they don't self-flatten when they hit armor, but penetration mechanisms for arrows against hard armor aren't terribly dependent on having a sharp point, and against soft armor (leather, cloth, etc) the arrow doesn't flatten anyway.

GURPS treats hardened steel impaling weapons as getting an armor divisor against most armor (I don't think it's reflected in the rules, but I feel hardened steel armor should count as GURPS Hardened - although that may be double-dipping to include both Hardened and the increased general DR it receives). Are you saying this is outright inappropriate, or that the armor divisor of (2) simply overstates things? I feel (1.5) might be more appropriate, although I understand why GURPS avoids that divisor (as well as why it typically avoids 7 as a multiplier/divisor). Heck, considering TL 4 Hardened Steel for armor is typically around x1.2 to DR, an armor divisor of (1.2) might be appropriate.

Originally Posted by Rupert

Composite Bow, ST13, and your super-bodkins, and you're good to go. 1d+3(2) imp does 1d x2 vs basic set's plate. Using LT's higher DR plate requires more points, but then we're fixing one problem made by adding something by adding something else. Easier to just not add it in the first place.

I don't recall if DR rounds up or down when armor divisors are in play, so I was just going with needing 2d(2) imp to reduce DR 7 to DR 3.5 - or 1d - so that you end up with 1d imp penetrating. That calls for ST 15 and normal Hardened arrows (or ST 13 and Fine Hardened arrows). If DR 7 gets reduced to DR 3, you can do it at ST 13 and normal Hardened arrows (or ST 11 and Fine Hardened arrows), while if it gets reduced to DR 4 you'd need ST 17 and normal Hardened arrows (or ST 15 and Fine Hardened arrows). Where in that split it happens dictates what sort of melee weapon you'd need. At ST 13 (vs DR 3 with AP arrows), you can't quite match the super-bodkin's wounding - a Halberd gets you to 3d cut, which the armor functionally reduces to 1d cut. At ST 15 (vs DR 3.5 with AP arrows), a Dueling Halberd or regular Poleaxe suffices - sw+4 cut gets you to 3d+1 cut, which the armor functionally reduces to 1d+1 cut, comparable to 1d imp (average 6.75 HP wounding vs average 7 HP wounding). At ST 17 (vs DR 4 with AP arrows), a glaive is sufficient for the above. Note in all cases, the melee weapon outperforms the super-bodkin in wounding against most armor (we've been looking at literally the best protection available at low TL, prior to the publishing of LT).

Originally Posted by Verjigorm

The big problem here is that the damage values for bows is just wrong. I mean, the composite bow is, what, thrust +3imp? So a ST 12 man launches an arrow with a comparable energy to a .22? Nah, that doesn't pass the smell test.

We could halve the damage of bows, and it wouldn't be too much.

I believe the Cinematic Scale for bow damage in "The Deadly Spring" works out roughly comparable to the GURPS ST table (at least in the range of typical human ST), while the Realistic Scale is half of this. I've also heard that the GURPS wounding results for ST-based weapons against unarmored foes seem in the realm of realism, however (although they accumulate too effectively, hence optional rules like Conditional Injury), which means cutting bow damage in half may get bows more in line with how they behave against armor, but make them too weak against unarmored foes. A possible solution would be to give all ST-based attacks an armor divisor of (0.5) - those that are already (0.5), like wooden stakes, would be either (0.3) or (0.2), while those that are (2), like Hardened Steel estocs and arrows (or bodkins), would simply have no armor divisor. Alternatively, leave armor divisors for these weapons the same, double all DR values, and give firearms AD (2) (AP ammo would be either (3) or (5)).

All that said, I'm not entirely certain a moderately strong man with a bow shouldn't have comparable penetration to .22 LR. It's well-known to be a pretty anemic round, after all.

[RyanW]

Originally Posted by Rupert

A professional baseball pitcher throws a ~145g ball at up to ~45 m/s, for ~146J of kinetic energy. That's close to the energy of 'standard' velocity .22LR rounds (and at least equal to a .22LR standard fired from a pistol). A good bow should do better than that.

A modern big-game hunting bow has about half that kinetic energy. In testing, a replica 150 lb warbow maxed out around 130 J.

[Anthony]

Originally Posted by Varyon

GURPS treats hardened steel impaling weapons as getting an armor divisor against most armor (I don't think it's reflected in the rules, but I feel hardened steel armor should count as GURPS Hardened - although that may be double-dipping to include both Hardened and the increased general DR it receives). Are you saying this is outright inappropriate, or that the armor divisor of (2) simply overstates things?

The whole concept of generic armor divisors isn't terribly realistic, but hardening your tip doesn't change the amount of energy required to penetrate armor -- it just changes the amount of energy lost to damaging your penetrator, and prevents damage from converting your penetrator into a shape that's less efficient. As such, against soft armor that won't significantly damage the arrow in the first place it doesn't do anything, nor does it really change the energy required to force apart a link of mail. It would in principle matter for penetrating plates, except arrows don't really penetrate plates in the first place.

[Ulzgoroth]

Originally Posted by Anthony

The whole concept of generic armor divisors isn't terribly realistic, but hardening your tip doesn't change the amount of energy required to penetrate armor -- it just changes the amount of energy lost to damaging your penetrator, and prevents damage from converting your penetrator into a shape that's less efficient. As such, against soft armor that won't significantly damage the arrow in the first place it doesn't do anything, nor does it really change the energy required to force apart a link of mail. It would in principle matter for penetrating plates, except arrows don't really penetrate plates in the first place.

Even very thin plates? Low Tech's DR 3 light plate is equivalent to about 1 mm of GURPS-standard steel. And implicitly includes padding and some fudging for surface effect so it might be as little as 1 mm of weaker metal.

[DanHoward]

Originally Posted by Ulzgoroth

Even very thin plates? Low Tech's DR 3 light plate is equivalent to about 1 mm of GURPS-standard steel. And implicitly includes padding and some fudging for surface effect so it might be as little as 1 mm of weaker metal.

At point blank range, heavy warbows shooting hardened steel arrowheads can easily penetrate 1mm unhardened iron plate. At 2mm (with no underpadding), the depth of penetration drops to around half an inch, so barely deep enough to cause injury.

Source: Bourke and Whetham, "A report of the findings of the Defence Academy warbow trials Part 1 Summer 2005," Arms and Armour, pp.53-82.

[Verjigorm]

Originally Posted by Rupert

A professional baseball pitcher throws a ~145g ball at up to ~45 m/s, for ~146J of kinetic energy. That's close to the energy of 'standard' velocity .22LR rounds (and at least equal to a .22LR standard fired from a pistol). A good bow should do better than that.

This is consistent with what you'd expect from a bow of 100+ pounds drown for a couple of feet.

Oh, and I specified ST13. [/nitpick]

ST 13 is 1d+1 thrust, right? So 2d imp out of a warbow. Which is comparable to .38 special in gurps damage. .38 special commercial loads can penetrate anywhere from 2.5 to 5mm of mild steel, depending on the projectile(lighter FMJs penetrate better than heavier soft points, for instance). .380 ACP has somewhat worse performance, but should still reliably penetrate 2-3mm of mild steel.

Joe Gibbs has demonstrated that 165lb warbows cannot consistently penetrate a .5% Carbon steel breastplate ranging from 1.5mm to 2.5mm, at 10m and 25m ranges.

So, yeah, I believe that the damage values of guns and bows are not anywhere near right. Medieval plate armor is not going to protect you against even notoriously under powered pistol calibers.

This also gets into an issue with the way real world projectiles interact with armor and the soft squishy stuff it protects. Thinner thicknesses of armor tend to remove very little energy from the penetrating round, allowing very deep penetration in soft tissues.