Crossbow Question

[Rasheab]

So I'm sure there are some folks around here who know the answer to this question.

Crossbows can only have 15 pounds of pressure when ready to fire. But I've been told that crossbows at that poundage are practically useless (they don't shoot very far).

So my question is: why is the limit 15? If they don't work very well, why isn't the limit higher? I don't know all the tricksy poundage differences mathematically between bows and crossbows, but if a bow can shoot decently far at 35 pounds, why are crossbows gimped?

Thanks.

[Big King Jimmy]

Because a bow needs to be half drawn at 15 feet. Since crossbows can't half draw, they drop their poundage in half.

Now, that's where someone **** up. See, poundage per inch on a bow isn't linear. But them's the breaks.

[Davit]

Next up, if you want to discuss rules move to the correct forum. This one is how to build, not the rules say something.

[Arrakis]

Move this to the rules forum if this is too much of a digression, please.

Is anyone else watching the new Dag crossbow rules with any interest? It will be nice to be able to see how it works out for them without having to do all of the play testing and such ourselves.

[Forkbeard]

Last winter we went through all this. Some clever sob or another did the math on what it wou8ld take to have a 14" arrow( that's half draw) leave a xbow at the same velocity as a 28" arrow leaving a regular 35# bow at half draw(14").
The answer is 30 to 32# * 14".
This also can be figured out by seeing what your legal 35# * 28" bow pulls aty 14". That also says about 30#.
So, if someone built a (or a few) Xbow that pulled 30# * 14" and brought it to a war(or all major wars) one summer, we could get the rules changed.
Look up the old threads and see for yourself. The math is good. It will work and be safe.
Somebody with some money and time to spend on making the test xbows is all we need.
FB

[Arrakis]

Somebody brought a small crossbow to Beltaine 08 that worked great. If I recall, it was something like 50+#. I was shot in the face with it from, say, 30 feet. No pain. Certainly no worse than a normal arrow.

Who had that and what was the actual poundage, I wonder...?

[Cyric]

There was a crossbow at fest this year. we shot someone point blank in the face and it hurt a lot less than a normal arrow, but it pulled more than 15#. Outside of a rules change with all the math, and an easy way to verify that math at weapon check, the best thing you can do is build a crossbow, test it in your realm, then bring it to an event and let the weapon checkers and marshals look at it.

[Rasheab]

I posted originally in the foam smithing, because I thought that was more appropriate place to discuss the safety of the weapon which presumably led to the rule. I know the subject of the rule itself has been brought up before, so I didn't want to do it again. (Also I couldn't respond in this forum until earlier today.)

But since it's here, I have a follow up question. How does one measure the poundage of a bow/crossbow? If one is to build a working crossbow at higher poundage to test, it's an important question.

[Big King Jimmy]

There are various bow testers available to buy. It's pretty easy, you knock an arrow, the bow tester is a scale that fits around the string. You pull the tester which pulls the string to 28 inches, and then read the tester (most have their gauges freeze at the highest poundage delivered until you reset them.) It can also be done with a fish scale, but in that case you have to be able to read the scale on the side of your face.

[Forkbeard]

And for your building info, I beleive a crossbow that pulls 30lbs * 14" will be what you're going for. That will be the most powerfull crossbow that is still putting arrow out at the same force as a regular bow at half draw.
FB

[Oznog]

Been there, done that, launched several threads on it.
http://board.belegarth.com/viewtopic.php?f=66&t=26058
http://board.belegarth.com/viewtopic.php?f=66&t=18412

Crossbows should be reduced in power due to not being half-drawable, but
the idea of a 15# crossbow being half the draw of a 30# handbow is incorrect.

In reality, a crossbow at 45# * 10" power stroke is about half the draw. I know that some people have a hard time understanding that but that's consistent with the physics of the shorter draw, measured tests, and a ton of my LARP experience with it. As I got into in one of the earlier threads listed above, stick the same arrow you just shot out of a handbow and at pointblank range it is already moving slower than it would be once it's left the handbow at full draw and traveled past the 20ft minimum range for fulldrawing.

At 45# * 10", there is a danger of people simply not noticing it even at moderate ranges BUT getting hit in the face up close is pretty much the same as getting hit in the face with a handbow from a ways off. It's pretty much the "sweet spot" between being unsafe and being ineffective. I played for a bit with 38# * 10" and people weren't even noticing being shot up close fairly regularly. 15# is not just "gimped" but absurd, you can just throw an arrow significantly faster at that point.

Crossbows should generally not be measured by draw length, that is not a well defined term and is wildly inaccurate. Power stroke is accurate and if you're going to measure something, measure that!

A crossbow with a realistic form will by ~ 10" power stroke at most. You only find greater ones when someone takes a fiberglass kid's bow and puts it on a stick or something.

[Elebrim]

The math is sound, I'm sure we can agree on that. But someone needs to actually propose the rule changes in the next voting session, otherwise this whole discussion is moot. Something along the lines of:

(NEW) 1.4.8.3. The Maximum poundage allowed on a crossbow is 45lbs at a 10" power stroke.

And to accommodate for the physics at minimum range,

3.8.2. A half draw or throw for Class 4 Weapons under a range of 15 feet is required. It is illegal to fire a crossbow at under a range of 10 feet.

[Mekoot Rowan]

Elebrim, did I miss something? If the math says that a 30# Xbow at 10" power stroke (after reading this thread I am even more confused about the numbers) is equal to a half draw, then why would we need to limit firing at under 10 feet? What would be wrong with simply leaving things as stated that any projectile must travel it's own length to score a legal hit and not worry about close firing crossbows since they would be essentially equivalent to a half draw on every shot?

[Oznog]

(NEW) 1.4.8.3. The Maximum poundage allowed on a crossbow is 45lbs at a 10" power stroke.

And to accommodate for the physics at minimum range,

3.8.2. A half draw or throw for Class 4 Weapons under a range of 15 feet is required. It is illegal to fire a crossbow at under a range of 10 feet.

I agree rules changes are necessary.
First though you've really got to go to inchpounds (refer to previous posts on this). 45#x10"=450ip. At 8" (which is not an unusual draw for a reproduction), you need 56# to do the same job. Otherwise, at 45#x8"=360ip and 360ip is WAY on the low side to be fighting with.

The selection of 450 inchpounds ALREADY implements the idea of half-draw. I can demonstrate that I'll just hold it out at arm's length backwards and shoot myself. It's one of the stronger hits you'll get but pretty much like getting fulldrawn at 20 ft-50 ft or so. There is not a substantial difference in energy in the first 10 feet anyways. But (also covered in previous posts) minimum ranges never worked in practice. The play-to-win fighters try to rush in and catch the shot inside the "min range", actually trying to make the situation occur so they won't have to take it. This is completely opposite of the safety goals but it is impossible to guess the person's intent and of course unfair to say you can't move within 20 ft or 10 ft of a loaded crossbow until he shoots. Then you have people arguing over whether the shot contacted at 9 ft not 11 ft so they weren't killed and the archer is dead vs they were killed and their hits on the archer did not count.

Min ranges in reality solve nothing really and cause major rules problems. Just establish the actual acceptable shot energy and use that alone. And 450 ip for unarmored LARP use is pretty much it.

[Elebrim]

Rowan - I just picked a suggested rule and rolled with it so someone would actually get something together. All too often these discussions either A) die out and lead to nothing or B) get hijacked into an idea that is way beyond the scope of what was originally discussed or necessary for correction of the problem.

Oznog, thanks for pointing out the minimum range loophole; I hadn't considered that possibility. I would still be concerned with people trying to pull off the point-blank shots, though, especially on the high end of the 450ip range. And given the complaints that have been made in the past over bows getting tangled in melee, a crossbow would probably be a similar risk.

[Oznog]

Oznog, thanks for pointing out the minimum range loophole; I hadn't considered that possibility. I would still be concerned with people trying to pull off the point-blank shots, though, especially on the high end of the 450ip range. And given the complaints that have been made in the past over bows getting tangled in melee, a crossbow would probably be a similar risk.

Ha comes from experience.

Well, I can say that there's no power difference between point-blank and 10 ft. Nothing you could discern readily. It can be measured on a chrono but it's not especially significant.

Now there is sort of a hypothetical danger zone where the arrow doesn't have room to clear the string, like if you placed it up against someone and fired (literally point blank). The force won't be particularly dangerous, all this means is there's 45# of string force pushing the person and bow apart which is actually pretty trivial, arrows produce way more force than that on impact. The arrow might break but I really don't know. I would not approve of such usage.

Honestly, in all my fighting with crossbows in Amtgard/HFS, this never even came up. And for that matter the exact same problem exists for handbows (like if they're 6" away and you release, there's not enough room for the arrow to clear the string before hitting them there either). It's never come up for them either, to my knowledge. So my recommendation would be to not bother making a rule for it, I don't see any problem needing to be solved but in my experience this is the kind of thing everybody's going to go around asking questions about and then misquoting it and again somebody arguing "hey I don't think that shot actually cleared the string when it hit me so I'm not taking it".

Is there like a central authority in Belegarth that actually works with archery questions, or is it a thing with an annual vote with the sitting monarchs?

[Derian]

Is there like a central authority in Belegarth that actually works with archery questions, or is it a thing with an annual vote with the sitting monarchs?

All rules changes are voted on by the war council, which is essentially a one vote per realm system. Votes take place quarterly.

[Oznog]

Ouch. I kinda had some ideas about sending you guys a loaner crossbow to go through. There's an obstacle there if there's no specific archery authority but scattered voting members which may not have archery experience. I'm not sure how to approach this one.

[Derian]

Do you make it out to any Belegarth events? I'm not sure where you're located, but that would probably the best bet as there would be a number of people who could examine it at an event.

[Cyric]

Ouch. I kinda had some ideas about sending you guys a loaner crossbow to go through. There's an obstacle there if there's no specific archery authority but scattered voting members which may not have archery experience. I'm not sure how to approach this one.

There are enough people with archery experience around that can inform the rest of war council what they find.

[Oznog]

There are enough people with archery experience around that can inform the rest of war council what they find.

Who might those people be? I'd be looking for someone with not only some technical experience but someone whose testimony before the WC would have some weight. Because yeah thinking about it the people who know what they're talking about and the people who get listened to are not always the same people When is the next War Council, anyways?

I don't get to play Belegarth myself, I'm in Austin, Tx and there's no group especially near here. I've done Amtgard like forever, played HFS just the same when HFS had a large group going.

[Cyric]

Kegg is on war council, is an experienced archer, and has been wanting to change the crossbow rules for a long time. he'd probably be the one to talk to.

[Derian]

Kegg would indeed be a good choice, I would think.

We're currently in a two month discussion period; voting will be held next in the month of December.

[Rasheab]

So Oznog, your math to change it to inch pounds looks pretty straight forward. So to test the strength, I would use a scale just like Jimmy mentioned, and then use your formula, correct?

[Oznog]

So Oznog, your math to change it to inch pounds looks pretty straight forward. So to test the strength, I would use a scale just like Jimmy mentioned, and then use your formula, correct?

Yeah. Measure the power stroke as the distance the string travels, not the distance from the nut to the front of the stock. 45# * 10" = 450ip. Or you can write the rule as a chart, any crossbow built as a crossbow (or one of those popular toy "pistol crossbows") and not hacked together out of something weird's probably gonna be 8"-10". 56#*", 50#*", 45#*". You can make the chart larger if you want to address stuff like kid's bows stuck on a biiig long stick if you really want to. Anybody can approximate for values in between without a calculator. 8.5"... well the average person would see 53# as the midpoint between 8 and 9, it calcs to 52.94# so that's just fine.

I try to measure the power stroke to 1/4" myself but whatever. So if you do have 8.25" and the guy without a calculator can't tell if that's 55# or 54#... well stop being OCD. The scale's not accurate to within a pound! Either one is only +/-1% off from the exact value there. But you DO need to consider at least the half-inches. Saying it can only be 50# * 8.01" (rounding up to 9") is off by more than 10% and in my experience that's a fairly noticeable drop in the normal >20ft range. Starts getting into the "nobody feels it" range again.

[Davit]

I know this sounds stupid, and I know that most of us can do math, however sometimes at 9 in the morning after a hard night of, well whatever we do at night math isn't going to be our strong point. The easiest way to do something like this IMO would be a table of some sort with a "if the string travels 8" max # is X" etc.

[Kyrian]

How about this (assuming 450 inch-pounds):

Code: Select all

String travel   Draw poundage
6                75
6.5              69
7                64
7.5              60
8                56
8.5              53
9                50
9.5              47
10               45
10.5             43
11               41


Like we do for quickly measuring arrow draw stops, we could set this on on the edge of a table.

[Black Cat]

Since crossbows are a part of the subject of archery, I have decided to add everyone who has posted here to the archery forum. Kegg has been added as well.

This topic is still best discussed here so everyone can see it, but crossbows have also been brought up in the archery forum and I don't want anyone who wishes to take part in this discussion to miss anything important that may come up.

[Davit]

That's exactly what I was looking for kyrian, just to lazy to do myself.

[Oznog]

Yep, that chart works. 6" is the Cobra pistol crossbow... the Trident type is actually a bit shorter. But it's kinda silly, once you get to pistol crossbow size it's pretty much impossible to build it too powerful since it's so crippled by short draw length. It's a waste of time to measure the pistol bows they can't be too strong.

On the other end, you won't get much over 10" (well, all mine are ~10.25"-10.5" actually) unless they're putting fiberglass kid's bows or huge fiberglass bars on a stick. There's no compelling reason to disallow this sort of odd homemade form IMHO, so you need a mechanism to calculate it. Well, note that above 11" or so the half-inches mean little (12"=37.5#, 12.5"=36#, 13"=36.4#) so there's no reason to use that kind of step above 11" at all. Since you're gonna round to the nearest pound at least the 12.5" and 13" limit are the same number anyways.

[Forkbeard]

What we need is to drop all this speculation about different draw lengths.
Draw length needs to be 14".
Anything else is going to add too much confusion to the argument.
\FB

[Oznog]

Doing that would make the rule wildly inaccurate. At one end would be my recurved prod design of 14" draw, 10" power stroke=450ip. Nobody but myself makes prods anything like this. At the other end would be someone trying to make an actual period copy like Iolo's. The one of his I have is 11.5" draw, 9" power stroke, but that's a recurve too. In fact anyone building a crossbow will almost certainly be working with fiberglass flats. That typically requires at least another inch at least of brace height to tension the prod in a functional way. 2" more is plausible, yielding a 7" power stroke.

Well, at that point your rule doesn't know the difference between say a 450ip big bow and a 315ip little bow, which is like not being able to tell the difference between a 25# and a 35# handbow.... or 35# vs 50#. That's far too wide of a gap. At that point the method is just presenting random, arbitrary limitations. And I gotta say this- at 450 ip it's already a bit "lean" on power. Going much lower starts to put it into the range of nobody feeling it at 50ft.

Most likely a max draw/fixed poundage limit would actually find "pistol crossbows" to be over the legal poundage, which is silly they tickle at most. Well you can argue that pistol crossbows shouldn't be allowed because they're dumb toys not in line with the original weapon form, and maybe there's something to that, but if your rule says they're illegally powerful then the wording of the rule limiting power is obviously flawed.

I've gotta say, it'd be nice if I were the sole supplier with a monopoly on 14" draw, 10" power stroke prods to reach the intended inchpounds. But that's not fair and not how LARPs actually work. Many people want to try to build their own because they lack the $ or like to build things and that's gonna typically result in a lower power stroke and/or shorter draw and it won't be able to meet the intended spec.

The chart's NOT all that hard. You can fit it on one line if you like.

[Davit]

I think what FB's trying to state is that you've never had to check over 300 arrows their bows and everything else that comes through weapons check. That's why I wanted a simple chart. By the way, I think if this happens, I wouldn't want to deal with anything under 1 inch increments. Having a **** ton of measurements with just the inch increment is going to be complicated enough, anyone trying to make me figure out how many foot-pounds a 4.2 inch draw that pulls X pounds equals during a weapons check is going to eat the end of my boot. Honestly weapons checking is a job that's **** and thankless enough as it is.

[Oznog]

Well can Belegarth's rules support "interpolation" ok?
6" 75#
6.5" 69#
7" 64#

If you drop the 0.5", it wouldn't take a rocket scientist to see that 6.5" = 69# or maybe 70# (you won't be able to read a meter with this sort of accuracy anyways). 6.25" would be ~73# too. But I'd say '5.01"-6" 75#, 6.01"-7" 64#', that is, not estimating intermediate values is too big of a jump.

Actually when I build bows I just use a chrono, it's much more accurate. I shoot the same weight bolt out of the reference bow and the one I'm working on and can see if it's shooting high or low.

[Forkbeard]

No Beles rules DO NOT support "interpretation.
All bows are 35# max *" draw max. Anything less is ok anything more is not.
Xbows need to be the same regular measurements.
FB

[Mekoot Rowan]

Fork, I don't know if you read or wrote wrong, but interpolation is totally different from interpretation. He means that you would essentially guess at what a good draw would be given that the power stroke falls between two sets of charted measurements. This wouldn't be very hard but it would be simpler if checker just took any abberation, like Davit's 4.2 inches or whatever, and just rounded down to the nearest whole number and tested from there.

It seems really rigid to force all crossbows to draw 14", any bow can draw a 28" arrow, so the rules there are good. A crossbow on the other hand would have to be designed to draw 14" only, no shorter or longer, so any small mistake in construction could leave you with a worthless weapon. Unless I'm misreading what is being said and the draw just needs to be 14" or less which would be perfectly fine since according to Oznog (who seems to have the most experience in crossbows in this discussion) 14" is rather large for the poundage we're talking about.

It seems like the chart Kyrian posted is the best and most fair option put forward so far. It looks fairly easy to use and requires nothing more than a measuring tape and a bow tester which are already available at weapons check.

[Oznog]

Yeah I'm asking if a rule *could* be worded that way, to intepolate. A chart going by inches is somewhat on the coarse side and the intermediate values for 1/2"es or 1/4"es are fairly obvious, no calculator required.

How would you even measure "draw length"? DL is a term defined by Archery Manufacturer's organization as going from the nearest part of the handgrip on the bow plus 1.75". It has no real meaning for a crossbow. Crossbows are all measured by power stroke- string travel- as an industry standard.

[Big King Jimmy]

In belegarth, we commonly use the term draw length to describe the distance from the strings at rest position to fully drawn. Is that the same as power stroke?

[Kyrian]

The way I'm visualizing testing this, we would put the crossbow so that the string in the resting position is aligned with the edge of the table. The crossbow is braced in place and the scale is then attached to the string and drawn back to the locking position with measurements taken for string travel and poundage. If the string travel falls between two of the known quantities, for example, between 7" and 7.5", then the crossbow would have to pull at or less than the value for the 7.5" string travel, in this case, 60#.

Does this sound reasonable?

[Oznog]

In belegarth, we commonly use the term draw length to describe the distance from the strings at rest position to fully drawn. Is that the same as power stroke?

That is "power stroke". However, that's NOT "draw length"!

Having 28" draw means 26.25" from the palm of your bow hand to where you anchor your fingers. The AMO defined that back in the 70's.

DL started out as measured from the FRONT of the bow. That measure came about to communicate what arrow length was needed. With broadheads, you can't draw the head any amount onto the shelf. So the far end of the shelf was the important measure. But bows have different shelf widths. A typical person with a 26.25" draw from one hand to the other found that with a 0.75" narrower bow shelf (longbow, etc) would call that a 25.50" draw. And he's like *, I used a 28" draw on a longbow and I asked for you to sell me a 35" * 28" recurve but you're telling me that means something else on a recurve?

AMO fixed that by simply defining the bow handle as being 1.75" thick regardless of how thick it actually is (for recurves, 1.75" from the deepest part of the grip to the front of the bow IS very common). So really they're essentially saying draw 26.25" from the deepest part of the grip (called Draw Length from Pivot Point, DLPP) and that's the 28" draw point. That's what Draw Length means today and it's the standard used to measure and label all bows by the AMO specification.

[Oznog]

The way I'm visualizing testing this, we would put the crossbow so that the string in the resting position is aligned with the edge of the table. The crossbow is braced in place and the scale is then attached to the string and drawn back to the locking position with measurements taken for string travel and poundage. If the string travel falls between two of the known quantities, for example, between 7" and 7.5", then the crossbow would have to pull at or less than the value for the 7.5" string travel, in this case, 60#.

Does this sound reasonable?

Well, you'd just measure the power stroke itself without drawing it. I mean string's here, locking point's there.
The only thing is, if a guy's got a 7.1" draw and you use automatically use the 7.5" limit, then it's off by ~6%. Eh, a little off but not too bad. That'd be like giving someone a 32.7# instead of 35# draw limit because of some technical detail.

The problem you're gonna have is exactly how to measure a bow. The string travels straight over the stock so the meter's hook will be pulled downward onto the stock which makes friction. And actually many bows will have a spring or something either on top of the nut position or behind it which gets in the way of the meter's path.

But keep in mind what's going on here. 450ip is pretty usable AND tolerable but if it does end up being 475ip it's not gonna take anyone's head off. It would be highly unlikely anyone could tell the difference. You just don't want to see escalation where a 475ip passes so maybe we can get a 500ip in there etc etc.

[Big King Jimmy]

wait, no, that's not how we do draw length either, we do it from the hand. A piece of tape 28" up the shaft is aligned with the front of the bow.

[Big King Jimmy]

But keep in mind what's going on here. 450ip is pretty usable AND tolerable but if it does end up being 475ip it's not gonna take anyone's head off. It would be highly unlikely anyone could tell the difference. You just don't want to see escalation where a 475ip passes so maybe we can get a 500ip in there etc etc.

Belegarth has no soft bounderies like this. I mean, hit testing, sure, I guess. But not with anything you can quantify. It would have to be 450IP and no more, if that's what the number was.

[Oznog]

Belegarth has no soft bounderies like this. I mean, hit testing, sure, I guess. But not with anything you can quantify. It would have to be 450IP and no more, if that's what the number was.

Well, if you measured a bow and the meter said 36#, realistically you wouldn't toss it off the field would you? It's beyond the accuracy of the meter.

[Derian]

Unfortunately, yes, that's often how it's done, regardless of how wrong it might be.

[Arrakis]

Derian:

That just means archers need to roll with at least two bows near max or one near max and one they're reasonably sure will test 5# light. For X-bowers, that would just mean accurate power stroke length measurement during construction and leaving a "safety margin", as it's known in engineering, of however many pounds of draw steps the bow down to the max allowable power at the next longest charted power stroke length.

So, if I built a x-bow with a 7 inch stroke, I'd build it to 60 pounds of draw, not the 64# I could get if I built a bow with a 6.9 inch stroke (the first case having the draw weight as the margin and the second case having the stroke length as the margin).

That accounts for checker error and for heat and other factors.



Simple.


Just don't bring a realllly near max bow or x-bow to an event without a backup and plan to arch all event because your bow just might fail.

[Derian]

Arrakis, that's really not an option for most people; bows aren't cheap by any stretch of the imagination, especially nice bows.

Really, weapons checkers should allow for margin of error on bow testers (and scales for melee weapons, which often is not the case).

[Arrakis]

Derian, I certainly agree that how it's done right now is not optimal. I was just saying that that's how I would account for the way it is done now.

Also, anyone who is getting into archery in this sport KNOWS they're going to be spending money (or should...). Arrow shaft replacement ALONE is a major investment if you go eventing a lot, not to mention replacing screwed-up heads, damaged fletchings, bowstrings, bow expenses...

If you're looking to save money, fight bluesword and plywood strap round.

[Angmarth]

I haven't read all of these, but I think what we all want to see is a crossbow that fires with approximately the same amount of energy as a standard bow. Someone may have already done this math, but bear with me.

Let's look at

Ex (energy crossbow)
Eb (energy longbow)

Ex = Eb

Really what we are looking at is KEx (kinetic energy crossbow) = KEb (kinetic energy longbow).

KE = (1/2)(m)(vˆ2)

KEx = (1/2) (mass of the quarrel) (velocity squared)
KEb = (1/2) (mass of the arrow) ( velocity squared)

I think it would be safe to assume that the mass of a padded quarrel would be approximately 70% that of a padded arrow.

Hence, m(quarrel) = .7 m(arrow).

KEx = KEb (Followed by substitution and simplification)

(1/2) (mass of the quarrel) (velocity squared crossbow) = (1/2) (mass of the arrow) ( velocity squared longbow)

(mass of the quarrel) (velocity squared crossbow) = (mass of the arrow) ( velocity squared longbow)

.7 (mass of the arrow) (velocity squared crossbow) = (mass of the arrow) ( velocity squared longbow)

.7 (velocity squared crossbow) = (velocity squared longbow)

.84 (velocity crossbow) = (velocity longbow)

This means that the velocity for the quarrel MUST be higher when it leaves the bowstring in order to achieve the same KE. In fact it must be 1.19 times greater, almost a 20% increase.

Using some crazy assumptions (such as a perfectly efficient bow to negate friction and poor design issues) we find that:

Since F = ma, we can substitute for the a and get F/m=a.

PE = (m)(F/m)(s)

Since the m's cancel out, we are left with PE=Fs.

This means that in a perfect world the draw length is DIRECTLY proportional to the energy stored. With a crossbow draw length no where NEAR the length of the bow, you need to up the force delivered by the same proportions. In theory (in the perfect world) a 70lb crossbow could be used at 14inches. Since we don't live in a perfect world and our bows are probably only 50% efficient (with crossbows being somewhere closer to 75%) we should look at a force something like this:

(.75)FxSx = (.5)FbSb

Using 14 inches as a MAX draw for crossbows you say:

Fx = 1.333Fb

In this case the rule would state:

A crossbow may have no more than a 14" draw, and no greater pull than 47lbs. In interest of ease, my suggestion would be to set the pull at 50lbs, a standard we have already seen in some games that works just fine.

[Forkbeard]

I did miss read ozongs post, sorry.
But my point was that we need standardized constuction of xbows. WC will never pass rules where you have to apply a chart and do math to figure out if something is leagal. They just won't. It would make weapon check take longer and nothing that makes weapon check take longer is going to pass.
If this means everybody can't bring whatever small peice of **** crossbow they have, so be it. Make your own to comply with whatever rules we settle on. I will.
Angmarth, you're totaly on the right track.