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Old 04-13-2012, 01:36 PM   #11
Flyndaran
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Default Re: When to use heavy war arrowhead or light? (Deadly Spring)

Ok, at least that's something. Thanks
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Old 04-13-2012, 02:43 PM   #12
DouglasCole
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Default Re: When to use heavy war arrowhead or light? (Deadly Spring)

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Originally Posted by Flyndaran View Post
Optimally I guess I would like enough information to pinpoint optimal arrowhead weights for a specific arrow.
But without getting the author to divulge possibly non-existent notes, I'm stuck with two types.
I suppose eye-balling it is the best one can do.
When in doubt, roll and shout. :)
Sorry, I'm in Japan, and can only get in front of my computer at odd times. Like now (5:40am local time).

For any bow in the design system, maximizing the weight of the arrow will maximize the efficiency of the energy transfer to that arrow, since the virtual mass of the bow will be basically constant, and you want the arrow to be as heavy as possible.

I built the light/heavy tables because some historical arrows require the use of a light head coupled with a light shaft to match weight. I suspect (but I never really plotted it out) that heavier tends to always be better than lighter just by the math (for a given bow, range is proportional to KE, and increasing mass increases efficiency, which increases KE).

But the overall reasons for light/heavy in the arrowheads themselves is to allow a toolkit to match historical arrows. You might also have a case where the arrowhead might be a rate-limiting step, and you want (for example) to put lightweight meteoric iron tips on arrows, but don't have that much of the stuff . . . so you want many lightweight arrows rather than few heavy ones.

That sort of thing.
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Old 04-13-2012, 02:48 PM   #13
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Default Re: When to use heavy war arrowhead or light? (Deadly Spring)

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Originally Posted by Ulzgoroth View Post
The benefit of a heavier arrowhead, from the article's formulas, appears to be that it lets you increase the weight of the arrow without increasing the diameter of the shaft. That boosts 1/2D range, as well as increasing the bow's efficiency, at the cost of max range.

You could get similar, though not the same, effect by increasing both the length and thickness of the arrow. (The difference being that your arrow weight would rise faster compared to your arrow weight/cross section.) I suspect there are practical limits on arrow length but so far as I can tell the article doesn't specify them. I'd generally keep arrow length around 1-3 inches longer than the draw length (as the only example that deviates from that is the medieval crossbow with its extremely short draw).
Yeah, pretty much this. I think I calculate minimum shaft diameter, but there's almost certainly a maximum where the thing is TOO stiff and doesn't paradox properly. Past that (which I didn't calculate) you'll lose Acc pretty fast. That probably sets an upper limit for the weight of the shaft (though that upper limit will vary hugely with the available wood selection; you'll need to apply GM judgement on what's available. Not everyone can just go off and knock together ironwood for the purpose).

Then, you can go heavy/light on the arrowhead. For an individual archer, heavy/light might not matter. If you're procuring a million arrows for a campaign, it might make a difference. I think the equations are biased to "heavier is better," but again, there's going to be a point where it's TOO heavy . . . but that was beyond the already-aggressive sanity-draining reach of the article.
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Old 04-13-2012, 04:41 PM   #14
Flyndaran
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Default Re: When to use heavy war arrowhead or light? (Deadly Spring)

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. . . but that was beyond the already-aggressive sanity-draining reach of the article.
That is the plight of gaming. You give us gamers the world, and we want the rest of solar system.

I'm mainly trying to make the perfect bows for SM+1 guys with strengths below 30. As an expert eyeballing it, would the physics bite me with those stats?
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Old 04-14-2012, 01:08 AM   #15
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Default Re: When to use heavy war arrowhead or light? (Deadly Spring)

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Originally Posted by Ulzgoroth View Post
I suspect there are practical limits on arrow length but so far as I can tell the article doesn't specify them. I'd generally keep arrow length around 1-3 inches longer than the draw length (as the only example that deviates from that is the medieval crossbow with its extremely short draw).
Not sure about the specific measure, but conceptually some limit like this makes sense (probably by proportion rather than fixed increment over draw length); at some point, the center of gravity of the arrow will be outside of the bow before the arrow has accelerated enough to be stable, and the arrow will drop off the bow.
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Old 04-14-2012, 02:09 AM   #16
DouglasCole
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Default Re: When to use heavy war arrowhead or light? (Deadly Spring)

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Originally Posted by Flyndaran View Post
That is the plight of gaming. You give us gamers the world, and we want the rest of solar system.

I'm mainly trying to make the perfect bows for SM+1 guys with strengths below 30. As an expert eyeballing it, would the physics bite me with those stats?
I don't think so. The danger here is that you'll need a lot of material to handle the energy input of someone that strong (ST 30 is about a 450-lb. bow) and you'll need to watch out for the virtual mass of the limbs.

I put together a bow for you that's 50% bigger than a usual longbow. It's an Osage Orange/Sinew composite recurve, with a draw of 45", it's 105" long, and a 1.7" diameter (reasonable for a 450-lb. bow).

It will fire a 50" Ash arrow with a heavy barbed war head about 470 yards, and do 3d (realistic) or 4d+1 (cinematic) damage when it hits. It will lose -1 per die damage per die at 408 yards.

This is, as they say, a credible threat. :-)

Cost of the bow is $2130 (!), arrows are $25 each (and 3/4" thick!).
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