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[GreatWyrmGold]

Or start with wood. As you said, crossbows are powerful enough that there's a lot less room for variables to outweigh statistical error.

[Urist Da Vinci]

Take a look at this gamelog excerpt:

You pick up the feather wood bolt with your right hand.
The flying feather wood bolt strikes Dwarf 2 in the head, but the attack is deflected by Dwarf 2's iron helm!
You pick up the AP feather wood bolt with your right hand.
The flying AP feather wood bolt strikes Dwarf 2 in the upper body, tearing the muscle and tearing the liver through the iron breastplate!
The AP feather wood bolt has lodged firmly in the wound!
The Dwarf 2 pulls out and drops the AP feather wood bolt.
You pick up the feather wood bolt with your right hand.
The flying feather wood bolt strikes Dwarf 2 in the right hand, but the attack is deflected by Dwarf 2's iron right gauntlet!
You pick up the AP feather wood bolt with your right hand.
The flying AP feather wood bolt strikes Dwarf 2 in the upper body, tearing the muscle and tearing the right lung through the iron breastplate!
Dwarf 2 is having trouble breathing!
The AP feather wood bolt has lodged firmly in the wound!
The Dwarf 2 pulls out and drops the AP feather wood bolt.
You pick up the feather wood bolt with your right hand.
The flying feather wood bolt strikes Dwarf 2 in the left lower leg, but the attack is deflected by Dwarf 2's iron greaves!
You pick up the AP feather wood bolt with your right hand.
The flying AP feather wood bolt strikes Dwarf 2 in the right upper leg, chipping the bone through the iron greaves!
A tendon has been torn!
The Dwarf 2 falls over.
The Dwarf 2 gives in to pain.

Normal feather wood bolts aren't penetrating the iron armor, but the AP bolts do penetrate.

These are the values for "AP feather wood" (I called it that because I expected it to be armor-piercing):

Code: [Select]

[PLANT:FEATHER_AP]
[NAME:feather tree][NAME_PLURAL:feather trees][ADJ:feather tree]
[USE_MATERIAL_TEMPLATE:STRUCTURAL:STRUCTURAL_PLANT_TEMPLATE]
[BASIC_MAT:LOCAL_PLANT_MAT:STRUCTURAL]
[USE_MATERIAL_TEMPLATE:WOOD:WOOD_TEMPLATE]
[STATE_NAME:ALL_SOLID:AP feather wood]
[STATE_ADJ:ALL_SOLID:AP feather wood]
[STATE_COLOR:ALL_SOLID:CREAM]

[SHEAR_YIELD:5000000]wood default 40000
[SHEAR_FRACTURE:5000000]wood default 40000
[SHEAR_STRAIN_AT_YIELD:0]wood default 1000

[PREFIX:NONE]
[DISPLAY_COLOR:7:0:1]
[TREE:LOCAL_PLANT_MAT:WOOD][TREE_TILE:5]
[TREE_COLOR:7:0:1]
[DEAD_TREE_COLOR:7:0:0]
[PREFSTRING:feathery leaves]
[DRY][GOOD]
[BIOME:NOT_FREEZING]
[SAPLING]
[SOLID_DENSITY:100]

The only things that I changed from the wood defaults were the SHEAR values. MAX_EDGE is still at the low wood value of 1000.

I can conclude that the SHEAR values are used to check if a bolt can penetrate armor. This is similar to edged melee weapons, where the armor/weapon material with the higher SHEAR_YIELD value "wins".

I can't make any conclusions about the damage done with increased SHEAR values given that the armor is penetrated. That would require further testing.

[GreatWyrmGold]

So...High shear yield and density makes good bolts?

[Joben]

Hey folks can anyone confirm something about the properties of ammo?

I think the Wiki is wrong but don't want to change it without consulting with others.

http://dwarffortresswiki.org/index.php/Weight

That page says that a piece of ammo has a volume equal to SIZE / 10
Meaning that a bolt/arrow has an effective SIZE of 15 cubic centimeter, instead of 150.

Iron has a density of 7.874 grams per cubic centimeter.
Putting it at 118 grams per arrow instead of the ~1.2 kilograms you'd expect if you go by the raw SIZE listed in it's erm... raw.
That would certainly make way more sense, I think medieval war arrows are variously reported as ~50-120 grams.

But it isn't true. In game, vanilla arrows show up as ~1 Urist, which is 1 kilogram. e.g. 50 iron arrows = 58 Urist.

(density of iron * Volume of arrow) * Number of arrows = ?

(7.87 * 150) * 50 = 59055 grams

Or 59 kilograms.


So yeh, dwarves do indeed seem to be firing 2.2 pound spears at what appear to be supersonic speeds.

[Urist Da Vinci]

...
So yeh, dwarves do indeed seem to be firing 2.2 pound spears at what appear to be supersonic speeds.

I made iron 20x denser, and then made 100 iron bolts in the arena. The resulting stack weighed 2355 urist. Dividing by 20 and by 100, you get each bolt weighing 1.18 urist, which is equal to 1.18 kg or 2.6 lbs.

[Joben]

K, I'm getting 1.18 kg per arrow too.

So removed the referenes to dividing by 10 and put in references to the sizes listed in the raws for weapons and ammo.

[Loud Whispers]

So yeh, dwarves do indeed seem to be firing 2.2 pound spears at what appear to be supersonic speeds.

The Dwarves were being a bit modest when they called it a crossbow...

[AutomataKittay]

So yeh, dwarves do indeed seem to be firing 2.2 pound spears at what appear to be supersonic speeds.

The Dwarves were being a bit modest when they called it a crossbow...

http://en.wikipedia.org/wiki/Spear-thrower Maybe they figured out how to mechanize this? I do notes a mention of 93 MPH spears...

[Zivilin]

Perhaps iron already has a high enough max edge that raising it doesn't help. Have you tried lowering it significantly?

Good point, I'll try that.

Or start with wood. As you said, crossbows are powerful enough that there's a lot less room for variables to outweigh statistical error.

Or that, if the previous doesn't give any results. However, from my data and the data from Urist da Vinci, it's pretty much certain that MAX_EDGE doesn't affect armor penetration at all. Shear Yield is responsible for that, apparently. I'll redo the weight tests and try to monitor the wound types this time. Maybe that will shed some insight on why heavier missiles do better. I haven't been observing the reports too closely when I performed the weight experiment (only average number of bolts), so I didn't observe whether there were any deflections.

So...High shear yield and density makes good bolts?

This would appear to be the case.

K, I'm getting 1.18 kg per arrow too.

So removed the referenes to dividing by 10 and put in references to the sizes listed in the raws for weapons and ammo.

Actually, if You consult the wiki page, the working formula for calculating weight is given as:

Weight (in Γ) = Density * Volume / 100,000

If You put in the figures for ammo and iron You do, in fact, obtain the correct answer:

Iron Bolt Weight (in Γ) = 7850 * (150/10) / 100,000 = around 1.18 Γ

Disregarding the division by ten would give You 11.8 Γ. The Volume calculation Size/10 for ammunition is correct in that regard.

I would guess that this represents the weight of the arrowhead? Since objects only have one core material, it would make more sense to qualify an bolt by type of metal used in the arrowhead than type of wood used for the shaft. So instead of implying we have 150 cubic centimeter iron arrow, its more of simplifying the whole bolt to a 15 cubic centimeter iron arrowhead.

It still weighs 1.18 Urists, though

[Joben]

Uhhh what...I have no idea what point you were trying to make...but you can't disregard the divided by 10, that's the entire point.

Since size and volume are explicitly the same thing in Dwarf Fortress, therefore the statement on the wiki that ammo volume = SIZE / 10 is a logical absurdity. Even in DF a thing can not be one tenth it's own size.

Simple math bears this own, demonstrating that individual arrows 150 SIZE ingame.

[GreatWyrmGold]

I think you're misunderstanding Zivilin.

[AutomataKittay]

Size don't necessarily means material volume, size can just as easily mean bulkiness of the item itself. After all, mostly hollow thing is fairly large, but not weighty, isn't it? I'd not be surprised if the size's more there to limit how much you can stuff into a quiver.

And I did the math and checked the raw myself, the formula on top of the page worked fine with 150/10 and using raw's density here http://dwarffortresswiki.org/index.php/Iron , instead of the number you picked out, if the actual weight is around 1.18.

[Zivilin]

I don't think I am misunderstanding, but I am probably not being clear enough. I shall endeavor to clarify my point to the best of my ability.

Once more, I would like to note that the Wiki page on Weight has the following weight calculation formula:

Weight (in Γ) = Density * Volume / 100,000

It then proceeds to list all Item Types and their Volumes in table form. My point is, the value of Volume is provided for the purpose of fitting it into the formula. The value of Volume is not meant to match up with SIZE values found in the raw files. For most item types the Volume provided on the wiki page does equal to Size. However, Ammo appears to be an exception. That is why under Volume it said SIZE/10.

This is easy to check. If Volume = 150 (density of iron from raws: 7850), then the wiki formula gives:

Iron Bolt Weight (in Γ) = 7850 * 150 / 100,000 = 11.8 urists

Right?

I think everyone agrees that it should be 1.18 urist for a single bolt of iron. In the case of Ammunition, Volume is not equal to Size for the purposes of weight calculations.

...

Scratch that. I just had a look at some weapons in the object testing arena, and an Iron Battle Axe weighed 6 urist, while an iron War hammer weighed 3 urist. According to the raws
Battle Axe Size = 800;
Warhammer size = 400;

Substituting this into the wiki equation we get:

Iron Battle Axe Weight (in Γ) = 7850 * 800 / 100,000 = 62.8 urists

Iron Warhammer Weight (in Γ) = 7850 * 400 / 100,000 = 31.4 urists

Soooo.... it would appear that the problem is with the wiki formula itself. Perhaps it hasn't been updated in a while (or someone missed a zero), but as fars as weapons go, it seems it should have the following form:

Weight (in Γ) = Density * Volume / 1,000,000

If Urists = Kilogram, this would make sense unit-wise. In the raws, Density is given in... milligrams per cubic centimeter, apparently, and Size/Volume is supposed to be in cubic centimeters, then Density*Volume gives us the weight in milligrams. Milligram = 1/1000 of a gram, Gram = 1/1000 of a kilogram, thus the 1/1,000,000 multiplier.

This should probably be verified on objects other than weapons.

[AutomataKittay]

Hmm, I think armor could be examined in the arena. Though I notes that weapon and armor are labelled as 'special' in the wiki list, probably because of their relative complexity compared to other things.

Looking at bins and barrels ( and various furnishings ) in fortress mode should be able to verify, I don't have access to the game at the moment.

[Zivilin]

I couldn't check armor, because I couldn't find any specific SIZE values relating to it. According to the wiki, there are a number of parameters which can affect armor size.

Data on weapon size is very easy to obtain, since it is given in the item_weapon.txt raw file. I checked a few more weapons and they all confirm the 1/1,000,000 multiplier formula.

However, I tested a few different types of stone furniture using the Volume data given in the wiki (I couldn't find furniture volume in the raws on short notice) and it turns out that furniture (doors, statues,chains, and also mined stone) agree with the previous 1/100'000 multiplier. So either the game Volumes/Sizes of furniture aren't the same as stated on the wiki, or there are two different weight formulas for different item types.