# Arrow Diameter Impact on Target



## Bobmuley (Jan 14, 2004)

IMO we should only be worried about radii of the 40 cm target and radius of the shaft.

20 mm radius for a 40 cm target's 10 ring. I only come up with a 1.4% "bigger" effective 10 ring between max 9.3 arrows and the 22s.

I do like how you look at it though!


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## markus_ger (Dec 1, 2016)

You are right, for indoors only the 40 cm target face is relevant. I was only adding the other target faces for cross-checking usability of thick arrows during summer outdoor FITA rounds in low wind conditions.

Your can calculate everithing with radii or diameters alike. You only have to be consistent or watch not not to mix values or formulas. You are talking about a 40 cm target face (which is a diameter) and the US 20mm 10 ring (which is the radius). The 22/64" and 93 mm arrow measurements are diameters again.

In case you still get different results I'm highly interested in your formula. Maybe my calculations are off.


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## whiz-Oz (Jul 19, 2007)

You still may be off if you are only considering the geometric calculations and ignore the straightness variation in the arrows.


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## nestly (Apr 19, 2015)

You've already figured out the math, the only remaining question is whether you can make the smaller dia shafts more forgiving than the large Dia shafts such that you can gain more points by shooting tighter groups vs gaining points due to line-licking. For myself shooting indoor, I score better with 23's than 27's because my X23 groups are smaller on average (center to center) than my X27's. As distance increases, the ratio of shaft diameter to ring diameter decreases, so the greater the distance, the fewer points you'll gain due to increased shaft diameter.


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## markus_ger (Dec 1, 2016)

nestly said:


> the only remaining question is whether you can make the smaller dia shafts more forgiving than the large Dia shafts


I will try to do so with the Goldtip '22 series. First I'll work on FOC by putting more weight on the tips. Next I'll try spine aligning the arrows. Finally I'll change normal nocks to pin nocks to avoid robin hoods. Currently I don't see anything I can improve about the fletching. If the arrows still don't group right, the spine is too stiff. It's 350 and my bow shoots better with 400s. Then I'll need a set of new arrows anyway. Is there anything I forgot?



whiz-Oz said:


> You still may be off if you are only considering the geometric calculations and ignore the straightness variation in the arrows.


@whiz-Oz: True, let's add arrow straightness and variations in arrow straightness (and spine) to the list of other things, that impact arrow flight and forgivingness.


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## Rick! (Aug 10, 2008)

markus_ger said:


> I will try to do so with the Goldtip '22 series. First I'll work on FOC by putting more weight on the tips. Next I'll try spine aligning the arrows. Finally I'll change normal nocks to pin nocks to avoid robin hoods. Currently I don't see anything I can improve about the fletching. If the arrows still don't group right, the spine is too stiff. It's 350 and my bow shoots better with 400s. Then I'll need a set of new arrows anyway. Is there anything I forgot?
> 
> 
> @whiz-Oz: True, let's add arrow straightness and variations in arrow straightness (and spine) to the list of other things, that impact arrow flight and forgivingness.


All your maths don't take into account that you can group arrows in the 10 ring off center or even in one hole that migrates as the round progresses. Even so, even if u only gain one point consistently, it's worth the change.

You can take a long time playing with point weight and such on your 22s. Or just run them through a shooting machine and cull out the ones that don't hit the same hole. I just did this last week and one shaft refused to nock tune.




nestly said:


> You've already figured out the math, the only remaining question is whether you can make the smaller dia shafts more forgiving than the large Dia shafts such that you can gain more points by shooting tighter groups vs gaining points due to line-licking. For myself shooting indoor, I score better with 23's than 27's because my X23 groups are smaller on average (center to center) than my X27's. As distance increases, the ratio of shaft diameter to ring diameter decreases, so the greater the distance, the fewer points you'll gain due to increased shaft diameter.


Why are your 23 groups smaller? More X's than 27's or the same? Can you explain it without the term forgiveness?




Sent from my iPhone using Tapatalk


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## nestly (Apr 19, 2015)

Rick! said:


> *Can you explain it without the term forgiveness*?


Why would I do that? That term represents a real and important factor in archery.


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## Bobmuley (Jan 14, 2004)

Regardless of how geeked out anyone gets with the thought and calculations the end result is shooting a bunch of scored arrows.


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