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Main Boards => PowWow => Topic started by: fnshtr on February 09, 2010, 10:12:00 PM

Title: FOC Calculation
Post by: fnshtr on February 09, 2010, 10:12:00 PM
First of all... let me ask forgiveness. I did do several searches and read until my eyes began to shrink.  :knothead:  

Could some kind soul please point me to the link that explains FOC calculation?

I want to experiment with this in hopes of increasing penetration on larger game (elk).

Thanks...
Wayne
Title: Re: FOC Calculation
Post by: patvro on February 09, 2010, 10:15:00 PM
http://www.archery-engineering.co.za/conversions/arrowweightandfoccalculator.htm
Title: Re: FOC Calculation
Post by: fnshtr on February 09, 2010, 10:19:00 PM
Thanks!
Title: Re: FOC Calculation
Post by: LongbowGuy83 on February 09, 2010, 10:32:00 PM
Is there a way to figure it on woodies? I'm simple minded also so keep in mind the simpler the explanation the better.  :bigsmyl:
Title: Re: FOC Calculation
Post by: DesertDude on February 09, 2010, 11:02:00 PM
Look in the "How To" forum section.
Title: Re: FOC Calculation
Post by: LongbowGuy83 on February 09, 2010, 11:05:00 PM
Thanks Mark. I will look.
Title: Re: FOC Calculation
Post by: Jack Guard on February 10, 2010, 12:43:00 AM
(ABP/TAL) - .50 x 100 = FOC%

Arrow balance Point (measured from the throat of the nock) divided by Total Arrow Length (measured from the throat of the nock to the back of point) minus .50 times 100 equals Front Of Center %.

An example would be as follows:
 ABP 18.25 / TAL 29 = .6293 - .50 = .1293 x 100 = 12.93% FOC
Title: Re: FOC Calculation
Post by: Rob DiStefano on February 10, 2010, 06:10:00 AM
Here's a link to an Excel file I built that'll give ya FOC and GPP ...

Excel .xls file (http://www.tradgang.com/docs/arrow_calcs.xls)

Enterprise Excel .xlsx file (http://www.tradgang.com/docs/arrow_calcs.xls)

   (http://www.tradgang.com/docs/arrow_calcs.gif)
Title: Re: FOC Calculation
Post by: LongbowGuy83 on February 10, 2010, 06:20:00 AM
Good deal. Thanks Rob.
Title: Re: FOC Calculation
Post by: fnshtr on February 10, 2010, 09:57:00 AM
Thanks Jack, Mark, Rob. The first calculator provided didn't have enough options for my set up.
Title: Re: FOC Calculation
Post by: Winterhawk1960 on February 10, 2010, 08:32:00 PM
So, what is an "acceptable" amount of FOC for elk sized animals ???

Winterhawk1960
Title: Re: FOC Calculation
Post by: mickeys4 on February 11, 2010, 10:27:00 AM
Here's a FOC calculator online.

http://home.att.net/~sajackson/archery9.html
Title: Re: FOC Calculation
Post by: trapperDave on February 11, 2010, 12:25:00 PM
QuoteOriginally posted by mickeys4:
Here's a FOC calculator online.

 http://home.att.net/~sajackson/archery9.html  
thats the one I use. nice n simple  :D
Title: Re: FOC Calculation
Post by: fnshtr on February 11, 2010, 12:38:00 PM
Don,

I'm shooting Traditional Only carbons from 3 rivers... with a 100 grain insert and 100 grains of weedeater string and 125 grain woodsman BH.

It appears that I've got a total arrow weight of about 585 grains. I would like to reach 600. Nothing "magic" about 600, just a nice round number and recommended by some as a minimum for elk. I'm considering increasing my BH weight to 145 or 160 grains.

I'm curious where my FOC will end up... but not aiming for a particular number.

Wayne
Title: Re: FOC Calculation
Post by: Rob DiStefano on February 11, 2010, 01:39:00 PM
imo, one should think about mass arrow weight, first.  i think the minimum for that would be about 9gpp (that is, 9 grains of arrow per pound of bow holding draw weight).  that plus a well flying, well placed sharp arrow and yer good to go.

foc is all about arrow balance.  there are theorized, and at best subjective claims of added penetration and enhancements to arrow flight.  use it or not, i don't think it's as important as ....  
 
use as heavy a holding weight bow as you can master, have well flying arrows, sharp c-o-c broadheads, and consistent arrow placement.  see, trad bowhunting isn't all that hard.    :D