Instead of a curve I would suggest setting the bow so it shoots a change up. It will be much harder for a deer to duck the arrow.

Now that was funny!!!

i've been thinking about the old water baloon trick. pull the string barely back and loft one, and while they are watching that slip in a fast ball.

Ya know...
a cuving arrow sure would come in handy for those bucks that always seem to stop right where a tree is blocking your view of their vitals.

If the arrow is hitting on the target or on on side of the target at 20 then when you go back to 40 it is on the other side of the target, I'd say you've got a curveball there. If it stays in the same position then it's probably an optical illusion