calculating bow speed
 

I saw a post a while back on calculating the number of inches the arrow drops from 20 yards to forty yards to figure out the speed. Does anybody know the numbers for that.

RE: calculating bow speed
 

Spread between 20 & 40 yard groups using 20 yard pin at both yardages:
220 fps (28.7")
240 fps (24.2")
260 fps (20.6")
280 fps (17.7")
300 fps (15.5")
320 fps (13.6")
330 fps (12.8")

RE: calculating bow speed
 

Yeh, that chart comes from edersbow and it doesn't work. I tried it and it was 34fps faster than my bow chrono's. According to the chart my bow shoots 294fps. From 20 to 40 yards there was right as 16" drop (2" groups at 40). That computes to 294fps. Too many chrono's said 260 + or - a couple.