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Old 05-03-2017, 07:11 PM
swaghauler swaghauler is offline
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Join Date: Jan 2015
Location: PA
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Default Some Basic Archery Terms

Here are some basic archery concepts and how they relate to archery in the real world. I'm guessing the Forum will have to work out which concepts are relevant to the game and how to apply them to the game engine being used.

The Characteristics of a Bow (or Crossbow):

1) Draw Weight: This is the amount of "pull weight," measured in pounds in the US, To draw back the bow. Common convention has Draw Weight ranging from 20lbs to 200lbs for a normal maximum (there are rumored 240lb bows, but I have never seen evidence of one). Draw Weights for crossbows range from 20lbs up to 500lbs for a crossbow that can be cocked by a cord or "goat's foot" lever (heavier crossbows require a windlass device to cock). I use 20lbs Draw Weight per point of STR for bows and 50lbs Draw Weight per point of STR for crossbows and list this as the STR needed to use this weapon. I think Draw Weight should be the primary measure of damage. When you look at the speed stats of bows published online, the standard bow Draw Weight used is 70lbs. Most modern Compound Bows can adjust their Draw Weight by about 10lbs in either direction. This task requires a skilled bow smith/boyer (AVE: Archery check?) to avoid damaging the bow's cam and pulley system.

Letoff: Compound Bows (and ONLY Compound Bows) have a feature called "Letoff." This is a point in the draw where the cams reach a "hold point" that takes most of the weight of the draw OFF of the shooter. This reduces the STR needed to hold back the bow string so the shooter can aim at a target. The typical "Letoff" of a Compound Bow is 80%, meaning that a standard 70lb Bow will only require 14lbs (STR 1) to hold at full extension. This "Letoff" is keyed to the cams and this means that you need to pull the Compound Bow back to the Draw Length it is set for to ensure "Letoff" occurs. Not pulling back that far not only prevents "letoff" from activating (requiring the shooter above to hold 70lbs/STR 4), but can damage the bow by causing "whiplash" which causes damage to the cables and cams (this is why you never "dry fire" compound bows). Composite Bows, Modern Longbows, Recurve Bows, and Self Bows DO NOT have this feature and you MUST hold their ENTIRE Draw Weight (which makes them harder to aim). They also have NO cam reset or letoff either, which means you can shoot shorter arrows from these bows (see below under Draw Length).

Minimum Arrow Weight: A bow's Draw Weight determines the minimum weight of arrow that it can shoot. An arrow must "flex" a little bit to both absorb the bowstring's energy transfer (from the bowstave) and to curve around the belly of the bowstave (this is often called "The Archer's Paradox"). Too much "flex" and the arrow COULD snap/shatter upon launch. This feature of an arrow is called "spine" in arrow selection guides. Regardless of an arrow's spine, there is a standardized weight for bows based on Draw Weight. This formula is 5 grains of arrow weight per pound of bow draw weight. Most big game arrows (and war arrows) will go 10 grains per pound of draw weight. Thus a 200lb Draw Weight bow would use a 1000-grain arrow. An 80lb Compound Bow will use a 400-grain arrow for hunting.

It's obvious that Draw Weight influences damage.

Draw Length: This is the length of arrow needed to properly fire the bow (or crossbow) at the velocity listed for that weapon. The standard draw length set by international standard is 28" of length. The standard set by the US bow industry (and the stat you most commonly find on the internet) is a 30" Draw Length. Draw Length is determined by the length of your arms. For every inch you change the Draw Length, you adjust your arrow speed by 10fps. Additionally, you will lose 1.7fps for every 10 yards the arrow travels. Traditional bows (composite, long, recurve, and self bows) can use ANY length of arrow. You just won't pull the bow back to its full draw with a shorter arrow and will have too much arrow out front (which can affect its flight) for longer arrows. Compound bows are "tuned" to use a SPECIFIC arrow length. overdrawing or underdrawing a compound bow can damage it. Compound bows can be fitted with "loops" (extensions tied to the bowstring) to allow the fire of shorter arrows. This will require a mechanical release (trigger mechanism held by hand) to use though. A compound bow can use up to a 2" Loop and Mechanical Release to adjust Draw Length.

Efficiency: You will see this trait often "espoused" by manufacturers (most compound bows boast a 95% Efficiency). It is the amount of a bow's power that is transferred to the arrow upon release of the bowstring. The longer or heavier an arrow is, the higher the bow's Efficiency will be. This is because the bow string will act upon the arrow for a longer time before the arrow parts with the string. A lighter arrow will SIGNIFICANTLY INCREASE the noise a bow makes (the "shawaaack" sound you will often hear during archery). This is because the excess energy that is left in the bow is causing it to "resonate" and make that noise. String silencers can help this. Heavier arrows will make LESS NOISE when fired because they absorb more of the bow's energy before parting from the string.

Based on what Draw Length influences, I think this should figure prominently into determining Range. I also believe it should (along with cross-sectional density) affect Penetration as well.

These are some basic terms you need to understand in order to model the damage of a bow or crossbow in Twilight.

Last edited by swaghauler; 05-04-2017 at 09:17 PM.
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