Bulk and ST for missile weapons
 

I know that there isn't a weapon design system in existence. I know that what I'm asking will more properly be answered if and when we get one.

But I need at least a provisional judgment call on it now.

I'm attempting to link crossbow size, weight and power with the poundage needed to draw it. That way, crossbows might be closer to reality than the current version.

Clearly, the more powerful a crossbow is, the stronger its construction needs to be. Some of that can come from better materials, but the most common method will always be a larger and heavier prod.

In addition, the longer the prod/lanth is, the more efficiency we get. That means a bow with a very small prod needs a very high draw weight to get the same initial velocity as a prod with longer limbs. It's therefore practical to have the prod of a dedicated war weapon be as wide as a man can easily use.

I can find the weight stats for crossbows of a given poundage in historical sources. I can also find their dimensions. Their capabilities can be estimated from testing data and the GURPS ST damage rules (which are faulty at high levels, but I'll use nonetheless to retain compatibility and relative power with other muscle-powered weapons).

But Bulk and ST for missile weapons do not correspond to any real world number that I can research. The best I can do is compare to similar weapons and guesstimate.

So, GURPS gives a Crossbow weighting 6 lbs. Bulk: -6 and ST: 7†. A Composite Crossbow weighting 7 lbs. has the same Bulk, but ST: 8†. A Repeating Crossbow of 10 lbs. is Bulk: -5 and ST 7†. A Pistol Crossbow weights 4 lbs. and is Bulk: -4 and ST: 7.

My questions are these:

a) What are the dimensions of these weapons?
b) How much does weight have to change in either direction before ST changes?
c) How much does Bulk change with increased size?

In other words, what Bulk and ST is a 18 lbs. crossbow with a lanth 4' wide? And so on and so forth.

Re: Bulk and ST for missile weapons
 

You might find it easier to compare to the Bulk of modern rifles from High Tech. At least those are for set specific models, and you can look up the dimensions online or in a Janes reference manual.

Regarding ST: Do you mean the Minimum ST to wield the crossbow, or the ST the crossbow can exert?

Re: Bulk and ST for missile weapons
 

I mean MinST.

And rifles are not shaped even vaguely like crossbows. A rifle of equal length to a high powered crossbow will be much less bulky because it doesn't have to have a wide prod that extends to both sides.

We can see that the GURPS Crossbow in the BASIC SET is only 6 lbs., but still Bulk -6, whereas rifles of that weight are usually much more handy.

What I'm trying to figure out is how much bulkier is the crossbow? How much does the inconvenient shape affect Bulk?

Re: Bulk and ST for missile weapons
 

Blah. Yes, of course there's a significant shape difference. My brain stopped working when it noted that rifles tend to be big, and well documented, and reached out and hit the reply button without further thought.

Regarding MinST, I don't think there are any hard formulas around at the moment, but I'm remembering a few "rules of thumb" which may or may not be as "helpful" as my rifle suggestion.

1) weight - to - MinST seems to scale linearly at a 1:1 ratio within the same group of weapons, for the same shape, judging from the Dungeon Fantasy rules for scaling up weapons for bigger barbarians. 1.5x the weight modifies the MinST by 1.5x

2) the "Combination weapons" box in Martial Arts (page 214) says, when talking about adding spikes, blades, and nasties to existing weapons (Which changes the balance!):
However, determining the MinST of a weapon can't be as simple as dividing weight by 1 if one handed and by 2 if two handed. It just doesn't return the correct numbers if you try that.

But that's a few clues, and the rule from Martial Arts will at least give you a way of "Fudging" the MinST for crossbows of a given weight by using one or the other rule to scale up or scale down.

If I had to guess, I'd say the Martial Arts scheme is probably more accurate because DF tends to lean in the direction of quick-and-dirty-and-cinematic.

EDIT: Although, on second thought, it may be erring on the side of higher MinSTs under the assumption that the weapon becomes more unbalanced the more geegaws you tack on.

Re: Bulk and ST for missile weapons
 

You know, Ive been thinking about this quite a bit myself as I continue to ponder the essential wood question and its effects on constructs.

Let me see if I can come up with a logic that can relate DR to HP of damge dealt or range. Essentialy, if DR is your ability to take damage with out loss of structural integrity and flexing the Bow/Crossbow is essentially the sort of non permenant damge that DR is meant to represent, could you draw a paralell?

Let me be more clear.

Can you define the min DR and HP of a crossbow as a function of its ability to impart Kinetic energy to a bolt?

Can you then take that DR and HP to let you know how much material is IN one so that you can then determine its apporpriate dimensions?

The reason I wonder is becaues Im curious to see if essential wood would make a bow/crossbow more or less useful for high strength creatures.

Get back to you soon....

Nymdok

Re: Bulk and ST for missile weapons
 

That last part is critical. The GURPS Martial Arts rules assume add-ons for the most part, and simplify the Min ST calculation. It's a good enough system for what it does, but it's meant to be a simplification. At the time, Sean and I discussed What Goes in Martial Arts and What Goes Elsewhere (mostly, Low-Tech). One of these was "rules for Min ST and weapon design" and they were to go Elsewhere.

So while I'll stand behind those rules, I'll only stand behind them for what they are: a simple way of dealing with customized and combination weapons, that gives close-enough results. A more detailed system was beyond the scope of the book.

Re: Bulk and ST for missile weapons
 

More.

Essential Wood pretty much makes the wood stronger without reducing its flexibility or other wood-like qualities. And the stronger the material for your bow or prod is for its weight, the less stored energy from your bow is lost in accelerating the bowlimbs.

Using Essential Wood would also allow a much higher absolute draw weight. While that would be all but irrelevant for bows meant for normal humans, since longbows can already be built as strong as any archer can draw, it could very well matter for fantasy creatures of human size*, but greater ST.

Making crossbows out of Essential Wood means that it would be possible to construct a high draw weight prod out of wood instead of steel. That would likely mean higher efficiency and thus better range and damage than a bow for the same ST made out of steel.

I suspect that Essential Wood is even better than horn and other materials used in composite bows. A perfect fantasy weapon would be a laminated or composite bow that has all the wooden components subjected to the spell.

The weapon could be a very light reflex bow, apparently too fragile to be used for anything other than sport, but due to the much stronger magical materials in use it would actually draw almost 200lb.

*Note that creatures larger than humans can use bows with a much longer draw length than was done historically. Since stored energy is a function of draw length times draw weight, this means a stronger bow for the same ST. Given that a fantasy giant would also have higher ST than a human, it becomes easy to see why people are scared of giants. Of course, single staves of good wood large enough to construct a giant bow might be hard to find. In that case, Essential Wood could be used on inferior wood in order to make it suitable.

Re: Bulk and ST for missile weapons
 

One thing worth mentioning is that Bulk doesn't correspond to just, well, bulk.

If you think of the instances where the penalty applies, there might be other factors involved. Penalty to hide is in the "bulky" factor, but "ease of fire while mobile" doesn't just depend on weight or dimensions, the trigger mechanism greately helps to fire while running, and since Bulk is used to determine the penalty to shoot while running, the number should be modified by that.

Mass is a factor (which translates to HP/weight);
Distribution of mass (how easily you can move it around, balance);
Ease of use (including firing mechanism);
Volume (how easy is it to hide?);
etc...

Take a pistol, for instance, no matter how light it is (in fact it can have a theoretical mass of zero) it still will have a non-zero Bulk number (probably still -2) because it's still tricky to hide. Same goes for bows and firing while running, the coordination is tricky, regardless of weight, size, etc (it requires a certain alignment of several moving parts: body, arms, bow, bow-string, hand, arrow... and they're all moving).

Re: Bulk and ST for missile weapons
 

This is very true.

And somewhat problematic. For example, a well-designed trigger for and the addition of a pistol stock to a crossbow (instead of a period nut and rifle stock) might make it easier to shoot on the move, but if the rifle butt isn't shortened as well, it won't make it easier to hide.

I'm thinking that the best Bulk I can hope for with a usable crossbow is -3. That would be one with a pistol grip, no stock and a compact prod. It could be quite powerful (historical examples exist in 760lb versions) and require a cranequin or windlass of some sort to reload, but for a single shot assassination, it would be ideal.

I'm still not certain what the maximum Bulk would be for a handheld crossbow. The largest would have more than a 4' prod and a stock of similar size, perhaps a little longer. A stirrup was fitted in the front of the weapon to help draw it. The heaviest crossbows would weight around 20 lbs. Any thoughts?

Re: Bulk and ST for missile weapons
 

It's also weird that there aren't rules for modifying the weight of a bow, whether it be ST10 or ST20... like you said, increasing the limb length adds more material. One possible justification is that it's possible to pull this off with changes in angle of the cord, curved design, type of wood, and whatever else is relevant (I don't know much about archery or bow-making/fletching).

Of course, crossbows have additional parts that scale with limb breadth, so even if the difference of weight for limbs is negligible the rest of the paraphernalia will still increase the weight a little.

While crossbows in history could grow to human-size and needed to be cocked with a stirrup and your foot, I don't think the crossbows in Basic/Martial-Arts get into that, they're just the ordinary 2-handed variety.

I also think that the realistic resolution of these crossbows also reflect the lack of material about them. Sure, we can differentiate the subtleties between several types of rifles, pistols and SMGs, we know a lot about them, and they're produced in series that share common traits. X-Bows weren't and we don't know a lot about them. "Small", "Medium" and "Big" might suffice, and even if you change the statistics a little, it's pretty believable that a crossbow existed with those stats, as they probably varied a lot even in the same place, as crafting wasn't industrialized.

I realize that's not what you're looking for, but for now eye-balling is probably going to give you the best results, and even if they're not perfect, there probably were some crossbows around that could perform like that and you can get away with it, unless you're too optimistic (which I don't think is the case).

I think there are too many variables we don't know how to quantify in order to reach a weight, bulk and minST value. I suggest taking the smallest crossbow you can find historically and giving it the lowest weight, bulk and minST value in the rules, likewise for the biggest historical crossbow that could be held, cocked and fired with 2 hands only. Everything else fits in between.

Re: Bulk and ST for missile weapons
 

I'm almost inclined to go with the Dungeon Fantasy rules for scaling weapons up, going with double weight for double ST (starting with the listed weapon), and then interpolating. But that's including making the whole weapon large (for instance increasing the draw length on a longbow by 50%)... Bleh.

Re: Bulk and ST for missile weapons
 

For crossbows, at least, if you increase the draw weight but don't increase the power stroke (the distance the string travels), you don't add much initial energy to the bolt at all.

That's why my treatment assumes that it's possible to vary prod size relative to ST and thus effiicency. Some steel bows will be extremely ineffient, but the high absolute draw will still allow them to retain effectiveness.

I'm confining myself to handheld weapons usable by SM 0 people. I plan to include tables that allow one to select the desired draw weight, material used for the prod and the approximate size of the prod relative to draw weight.

I'll also include several worked examples and note what ST can easily draw them.

I'm looking for help with eyeballing it. I've already benchmarked -3 Bulk as the handiest possible, now I need a good guess for the 20+ lbs. monsters mentioned above.

Re: Bulk and ST for missile weapons
 

Well, looking over the crossbows, bows and firearms it's safe to say the maximum Bulk penalty should be around -6/-7. Nothing I see has a bigger bulk number (except longbows), and a crossbow shouldn't be harder to fire while moving or to hide than a huge bow (which is -6/-7), it definately shouldn't be as much as -8, since any 2-handed crossbow, no matter how massive, if usable will be easier to fire on the run than a longbow, IMHO.

Since a regular crossbow is -6, let's assume the largest beast of it's kind will be -7, making it's larger dimensions comparable to an actual bow (regular or composite).

Weight is trickier, but using Bruno's suggestion, lets take a SM approach. Direct proportion is out, since we don't scale up the entire crossbow, only the relevant bits. Let's assume half, it's as good a guess as any unless somebody can figure out just what bits need to get bigger and how much they weigh. If a regular crossbow weighs 6 lbs for ST7, then ST14 will weigh 9lbs, and ST21 will weigh 12lbs. Damn heavy, but not impossible to use, probably the biggest crossbow a human can use effectively (using a Goat's Foot and a perk for +2 ST with Crossbows you only need ST15 to do it).

I'll say this though: from what Basic seems to hint, or maybe that's just my understanding, high ST bows and crossbows are not meant to be either heavier or more expensive. That's not realistic of course, but maybe the mechanic I suggested might be too harsh. You be the judge.

Edit... so a 18lb crossbow would require ST28 and theoretically a bulk rating of -7, although something this heavy probably doesn't qualify for regular 2-handed use anymore (even with the perk and a Goat's Foot, you'd need ST22 to cock it), at this point -8 for bulk might be believable.

Re: Bulk and ST for missile weapons
 

I don't agree.

I don't think any crossbow intended to be used as a battlefield weapon will go over this, but many crossbows were intended for sieges only.

And since a regular crossbow with a selfbow prod and weighting only 6 lbs. is Bulk -6, I'd think that siege crossbows of more than three times the weight would be much more.

Let's also keep in mind that a crossbow has much of its weight concentrated in the front. It's nowhere near as handy as a rifle of equal weight and length. This causes no problems when fired from a rest or even a stand on a castle wall, but it's hard to run and shoot with a monster like that.

I don't think it's fair to assume that a small crossbow designed for battlefield use and a huge one designed for be fired only from a mount on a castle wall would differ only by -1 in Bulk.

We know the range and penetrating damage of a 18 lbs. siege crossbow. We can also look up the range and damage of several other weights.

I don't have any difference finding weights. I need to know what ST a given weight requires in order to use the weapon.

And I'm not speaking of the ST to cock the weapon or the ST of the attack it delivers. I'm speaking of the MinST stat that ranged weapons have.

Re: Bulk and ST for missile weapons
 

I thought you said you were only talking about regular 2-handed crossbows, not siege or mounted ones. If that's the case, then hell yes, bulk -7 doesn't cover it.

As for the small differences in Bulk within "hands-held" crossbows I think a 1 point difference can be a big one, I don't view bulk in a linear scale. It's more of a bell curve to me, on the extremes a +/-1 covers a lot of differences, "low resolution", while near the middle (-3 to -5) a single point of difference can point to subtle differences. This is a personal view though, I feel that once it's pretty darn big, just making it bigger won't matter as much, same goes for small. However, I do agree that -7 or even -8 is generous for siege crossbows, but those are not your garden variety and I didn't think we were discussing them.

Edit: as for minST, yeah I screwed that up, got that mixed up with the ST to actually cock and fire the x-bow/bow...

Re: Bulk and ST for missile weapons
 

I'm discussing any weapon that can be used as a handheld crossbow.

Most of the larger variety were usually only used in sieges, but nothing prevents a PC from carrying it around. Well, except high Bulk.

The limiting factor with a high ST crossbow is that efficiency drops when you don't have enough draw length. The lightest draw crossbows might actually achieve bow-like efficiency, but the 1200lb monsters extraordinarily energy inefficient.

This is because increased the size of the prod at the same ratio as draw weight would produce bows too large to use comfortably. Hence, it seems from the historical record that Bulk was a factor that actively limited crossbow design.

So I want characters to have to select whether they want a powerful and efficient bow, which will be prohibitively bulky, or if they're willing to accept inefficiency in order to have a more comfortable weapon.

Re: Bulk and ST for missile weapons
 

Unfortunately, there don't seem to be strips and pieces of rules enough to lead to gameable stats, or even a precise definition of Bulk. At this point, I don't know nearly enough to even guess, and everybody else seems to have drifted from the issue.

Maybe if you posted the material you got from historical crossbows?

Re: Bulk and ST for missile weapons
 

Indeed. There is a noticeable dearth of rules.

You can see a short book preview that addresses the issue here.

Re: Bulk and ST for missile weapons
 

First, I took the time to write and research this throughly and Have actually submitted the idea to Pyramid for an article as it leads to some neat stuff.

The short version is this.

If you look up the Mary Rose you'll find a bunch of LongBow Dimensions.

Bulk Vs Str. Its not as big deal as you might think. You can Bump up the STR on a Bow/Crossbow without adding a signifigant amount to Bulk mainly becaue the length is the dominant factor contributing to the bulk as the 2-3 pound weight isnt generally considered bulky.

If the article gets rejected, I may publish the reults here because it is something that needs to be addressed.

Re: Bulk and ST for missile weapons
 

True. But those, I think, are not the ones we were having problems with. Nor were other dimensions, as these are accessible from the historical record.

The problem lies in relating these real world dimensions to the GURPS mechanics of Bulk and MinST.

One can certainly increase the draw weight of a crossbow without increasing the width and hence the draw length.

But that would result in a very inefficient weapon, since so little of the additional stored energy would be transmitted to the bolt in the form of initial velocity. I do not deny that it was done in the past, often enough, since with enough energy the lack efficiency could be tolerated and would still result in gains in absolute projectile energy.

But GURPS stats for the weapon would need to account for the lack of efficiency. A 760lb crossbow with a small prod and consequent short power stroke might not be any more effective than a 70lb bow with a much longer draw length.

Re: Bulk and ST for missile weapons
 

http://forums.sjgames.com/showthread...553#post721553


Finished...as good as my word, here they are...

Nymdok