F.O.C. Formula Measurements.

N2D · 01-02-2009, 03:52 PM

I have seen two different formulas for F.O.C. One is measuring from the nock groove where the string goes to the end of the insert. The other is to measure from the nock groove to the end of the broadhead or field point. Not sure if there is a right or wrong here. Anyone know if one is more accurate than the other?

Thanks

Ed

TFOX · 01-02-2009, 04:06 PM

Easton recommends to the end of the arrow shaft and to me,this would be correct when you are taking into account dynamic spine deflection.

From a pure mathematical standpoint,to the end of the point is probably correct.

01-02-2009, 04:09 PM

to me, a proper FOC calculation should include your BH length because you are calculating the complete arrow. But the industry standard I see does not.

Ed McDonald · 01-03-2009, 10:11 AM

Here is FOC as I understand it ..........

Ed McDonald · 01-03-2009, 10:14 AM

Let me try that again ..........
In the example below , the balance point is 3" in front of center . You divide the 3" by the total length (30" ) . In this case
the FOC is 10 percent .

TFOX · 01-03-2009, 10:41 AM

BUT,Easton does not include the point length as in the picture,imo,when dealing with arrows,you are better served to use their reccomendations.

Here it is right out of their arrow tuning guide.

Sorry about the size,I have resized it twice now on Photobucket and it is shown as being resized there but it won't translate to here,it keeps going back to full size.[:@] Wow,now it has resized[&:]

MeanV2 · 01-03-2009, 01:08 PM

To me it would be better to figure it either way and attain at least a 12% FOC for broadhead flight than not to figure it at all.

Dan

N2D · 01-04-2009, 05:07 AM

T-FOX I tried to run it that way and I do not get it to work out right. Must be doing something wrong. Is this the same as (ABP/TAL) - .50 x 100 = F.O.C. ?

Ed

N2D · 01-04-2009, 05:11 AM

Dan, I have been doing what you said. Using the two formulas that I have so far and getting an average making sure the lowest one is at least 12%. Still would like to know how to work any other formulas (like the one T-Fox has) if I can figure it out.

Thanks

ED

TFOX · 01-04-2009, 09:29 AM

It is the same as the one above it,just written different and doesn't go to the end of the point.