Bascially youeliminate one inch of arch for every 10 FPS increase in arrow speed in your trajectory from 20 - 40 yards.
That is incorrect. Arrow drop and trajectory are not interchangeablelike that.
"Arrow Drop" is absolutely the most useless piece of info an archer can clutter his mind with. All that does is tell you how much an arrow traveling XXX fps will fall, over XX number of yards, when shot perfectly level off a cliff. Who ever does that? Not I!
The archer launches his arrow at an upward angle, the arrow travels upward until gravity begins pulling it down and it starts to glide downward until itplops into the center of the target. That upward launch angle makes arrow drop numbers totally, completely, irrevocablymoot.
TRAJECTORY is the ticket!
When you calculate the trajectories of arrowsgoing the speeds Rob mentions at different yardages, the results will be very similar, if not identical,to his actual results.