Here is the link to ashby's report. the AMO formula is on page 11 in a call out box (it is not the only formula, bbut he certainly feels it is the most accurate approximation of the TRUE FOC which unless you are building weapons doesn't much matter).
http://www.tradgang.com/ashby/2007prologueupdates.pdf I pasted the text of the calculation below:
(1) Measure shaft length; bottom of the nock’s throat to the most rearward portion of the broadhead taper.
(2) With tip mounted, determine the balance point by balancing the arrow on a knife edge. Mark this balance point.
(3) Measure balance point distance; from the bottom of the knock’s throat to the balance point.
(4) Divide balance point distance by shaft length. This gives the decimal equivalent of the balance point’s percentage relative to shaft length.
(5) From this quotient subtract 0.50, the decimal
equivalent of 50%.
(6) Convert the resultant decimal fraction to percent by multiplying by 100 (or simply moving the decimal point two places to the right). This gives the percent FOC.
Topic: foc (Read 236 times)
