At the Wisconsin Bowhunters Assoc. (WBA) broadhead shoot this past weekend I gave them the $2.00 donation to go ahead and confirm my K.E., speed, draw, arrow weight ect. I see where they figure your Power Factor. This is my K.E. divided by my draw weight. Mine came out to 0.999 for my bow. What am I suppose to realize with this number? Our state average is 0.843. Is this some kind of measure of efficiency for a given draw weight?
I guess it's one way of looking at bow efficiency, energy out per amount of draw weight. Problem is that you work harder drawing say a 60 pound hard cam bow vs a 60 pound round wheel bow, and just going by draw weight doesn't tell you how much energy you're getting out for work put into drawing. The real way to figure efficiency is to determine the bow's stored energy and the arrow's kinetic energy. Then divide the kinetic energy by stored energy.
At least their way gives you some kind of number to discuss over the campfire. Going by their method, my Power Factor with 600 gn arrows is 1.02667. With 470 gn carbons it's 1.00213. 60 pounds at 33 1/2" draw.
If only we all had 33 1/2" draw lengths! We could use bows with 9 1/2" brace heights, set at 45 lbs and blow through every deer in sight! <img src=icon_smile_big.gif border=0 align=middle>
That is an interesting little discussion piece at least. I did my figurin' and mine comes out to 1.06060606. As stated above it would favor longer draw lengths, shorter brace heights and harder drawing cams.
Power Factor
