TL3 shields work as cover vs modern rifles?

[Xplo]

Originally Posted by Ulzgoroth

Only they're not made of shiny heavy duty steel.

Sure.. but a lot of people don't know that, apparently. They're going by something they saw in a piece of art, or in a movie, or something they thought they read about or heard somewhere.

Same mentality gets you 10 lb broadswords. After all, if you've ever hefted one of those fantasy display swords with all the glass gems and spiky bits and dragon heads on it, you know they're really heavy. Most people don't get to swing real swords around.

[Lupo]

Originally Posted by weby

An m16 will do 5d dame that is on average 17.5. Whereas the shield has a DR of 9 and 60 hp and according to the breaking shields rules is penetrated on HP/4+DR, thus with 24 points. Add the RD 5 chest armor and the total raises to 29 that requires one to roll five sixes to penetrate one point.

I agree with Hal here, shields should have *far* lower DR and HP. They're unrealistically resilient in GURPS and this creates the problems you are pointing to.

[Ulzgoroth]

The overpenetration rule that thin slabs provide only their DR as cover against small projectile attack types, with no contribution from HP, would seem to fix that problem if you use it instead of the rules as written for penetrating shields. And, on the side, makes it quite possible for a strong bow or sling to punch through even a heavy shield.

Incidentally, with ST 14 and a staff sling throwing lead shot, you get as much damage as a 9mm pistol. Wow.

[Rupert]

Originally Posted by Ulzgoroth

Incidentally, with ST 14 and a staff sling throwing lead shot, you get as much damage as a 9mm pistol. Wow.

Strength-based damage scales too well compared to the gun/beam damage scaling, This is a known problem with no easy fix, as fixing it means tearing apart one scaling rule or the other (the most likely candidate being the ST -> chart). It's also why my favourite fantasy missile troops are ogres with slings (firing cast lead bullets, of course).

[hal]

Originally Posted by Lupo

I agree with Hal here, shields should have *far* lower DR and HP. They're unrealistically resilient in GURPS and this creates the problems you are pointing to.

The question then becomes one of "What should the HP and DP values for shields be?"

It isn't all that hard to determine what the physical volumes required for various objects. Given density of materials used for the construction of shields, it isn't all that hard to determine what any given shield's weight should be based on the materials used. For example, Birch has a density of 41 lbs per cubic foot. Iron has a density of 489 lbs per cubic foot. Leather has a density of about 58.98 lbs per cubic foot.

The formula for calculating the volume of a shield would esentially fall under the heading "cylinder" where volume = pi * radius^2 * depth(or height) of cylinder.

Other needed information:
1 cubic foot contains 1,728 cubic inches.
1 inch = 25.4 mm


Thus, the dimensions of a round shield that measures 20" in diameter, 3/4" in thickness made of birchwood laminates, would contain roughly 235.619449
cubic inches in volume, and have an expected weight of about 5.6 lbs.

If one presumes that the DR of that Birchwood plywood shield is about equal to 1" thick wood (per page 558 of GURPS CAMPAIGNS), then any other DR bonuses to the shield have to stem from either (or both) leather and/or iron being added to the shield's facing.

I leave it to the reader to see if they can recreate the values for shields given in GURPS using real world data.

Oh, almost forgot...

GURPS assigns a DR value for 1" of iron as being 70. All it takes to calculate the thickness of iron required to grant a given DR value, is to determine the thickness of the iron required divided by 70 and that is the thickness in inches of the iron material. If you know the shield's basic dimensions (ie its radius), then you can determine how many cubic inches of iron is required to cover that shield to any given depth.

(Note: I do not know how thick leather has to be before it provides a DR of 1, but since leather provides a DR of 1 for covering the same as an iron plate cuirass, it shouldn't be too difficult comparing weights of the two to get some acceptable value of thickness to DR rating. There is already talk about how a plate cuirass should weigh about 8 lbs with a 1mm thickness.)

Basic numbers I ran using a spreadsheet:

Roundshield at 20" diameter
DR 7
Birch material
depth of wood = 3/4"

Cubic foot required for wood = .136 cubic feet
Cubic foot required for iron = .016
Weight of wood: 5.58 (for DR 1)
Weight of Iron: 7.82 (for DR 6)
Combined weight: 13.4 lbs
Combined DR: 7

A 30 inch shield by the way, would weigh almost 30 lbs in order to have a DR of 7!

Frankly? I don't think that the shields depicted in GURPS match that of Historical shields. My expectations of what a shield's DR should be, is that of perhaps 1 for the wood itself, and maybe 1 or 2 for leather facing of the shield. The leather facing should in most respects, be treated as ablative armor, so that over time, the shield's DR becomes hacked to bits and then the shield's hp become hacked to bits. The older GURPS rules reflect this - which is why I use those instead of the new rules

[Rupert]

Originally Posted by hal

It isn't all that hard to determine what the physical volumes required for various objects. Given density of materials used for the construction of shields, it isn't all that hard to determine what any given shield's weight should be based on the materials used. For example, Birch has a density of 41 lbs per cubic foot. Iron has a density of 489 lbs per cubic foot. Leather has a density of about 58.98 lbs per cubic foot.

If one presumes that the DR of that Birchwood plywood shield is about equal to 1" thick wood (per page 558 of GURPS CAMPAIGNS), then any other DR bonuses to the shield have to stem from either (or both) leather and/or iron being added to the shield's facing.

What you can do at this point is grab VE2 (yes, it's for 3e, but for now it's still a useful guide) and look up how many pounds of something it takes to get 1DR per square foot. Wood comes in at about 1lb/ft^2 per 1DR, or 1/40 x 12 = ~0.3" per DR (~3.3DR per inch).

Leather is given as 0.06 lbs/DR, but is flexible (strangle generous, and suggests that WWI tanks should probably have been covered in a laminate of hide and linen cloth). That's 82DR/inch, which is clearly ridiculous, so we'll assume it's just a denser wood (and we can assume it counts as rigid if it's moulded over and backed by the shield's wooden component), in which case it's ~5DR/inch.

So, a shield of 3/4" wood faced by 1/4" of leather gives us about 0.75 x 3.3 + 0.25 x 5 = DR3.725, which we could round to DR4. It also weighs (0.75 x 41 + 0.25 x 59) / 12 = 3.8 pounds per square foot, so a round shield 3" in diameter would weigh 19 pounds, plus a bit for the grips, etc. - say 20 pounds, and thus have 22 Health.

Now, as a shield is a thin object, clearly the rules stating that they only use their DR vs bullets, etc. apply. However, they'd get to use the extra 22/4 = 5.5DR against crushing and slashing blows, but only when seeing if the shield protects the wearer, so it won't last long if a big guys decides to target the shield directly.

[The Resistance]

So, WILL the Low-Tech supplement give more realistic rules for shields, and, if so, will they also factor in how bullets interact with them (granted, outside the scope of most TL0-3 civilizations, but it might be good to include it then, rather than leave a schism in the rule that will be filled later on)?

[Icelander]

Originally Posted by The Resistance

So, WILL the Low-Tech supplement give more realistic rules for shields, and, if so, will they also factor in how bullets interact with them (granted, outside the scope of most TL0-3 civilizations, but it might be good to include it then, rather than leave a schism in the rule that will be filled later on)?

Yes to the first, but no to the latter.

There are no new rules for how bullets or other pi attacks interact with the Damage to Objects rules. Just expect that you'd need to shoot pretty damn often at a given shield to ruin it, but if you just want to kill the bearer, treat the shield as concealment and fire through it.

Mind you, a heavy laminated shield might actually serve to deflect pistol bullets, but against a real battlefield weapon, you're out of luck.

[martinl]

Originally Posted by Lupo

I agree with Hal here, shields should have *far* lower DR and HP. They're unrealistically resilient in GURPS and this creates the problems you are pointing to.

The average rpg hobbyist expects low tech shields to be durable equipment. GURPS caters to this.

Realistic low tech shields, as noted, take a lot of damage in fights. Handling this in GURPS results in a lot of record keeping and maintenance.

GM: Lord Phluphernuttur, the Black Squire smacks you with his morningstar!
Player: I block (clatter) made it by 3.
GM: OK, the morningstar does (clatter) 11 points to your shield. Is that enough to bash through?
Player: hrm... minus DR ... carry the 2 ... ok 3 points get through.
GM: OK, roll on the shield penetration hit location table (clatter) it hits your helmet.
Player: Whew, I got DR 5 there.
GM: Are we using armor damage?
Other players: (run away screaming)

[Anthony]

Actually, I think some of these are general mechanical issues with 4e, not specific to shields. One problem is that penetration of barriers is based on the hit points of the barrier, which means making a barrier wider (without increasing its thickness) makes it harder to penetrate. Another problem is that most barriers don't actually have the same defense against all attacks -- for example, a rifle bullet can easily blow through more than 6" of wood, whereas 1/2" will stop most melee weapons. On the reverse end of things, against sandbags the melee weapon may have more penetration.