Greg,

<BLOCKQUOTE id=quote<font size=1 face='Verdana, Arial, Helvetica' id=quote>quote:<hr height=1 noshade id=quote>If you shoot an arrow out of a bow and srart heavy and then progressively get lighter the KE will continue to go up.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face='Verdana, Arial, Helvetica' size=2 id=quote>

<font color=green>BUT THAT IS NOT WHAT HAPPENS!</font id=green> It's just the opposite. Dropping arrow weight increases speed but decreases KE due to efficiency. As you go lighter, the arrows gradually lose their ability to absorb stored energy from the bow.

The only way you can gain KE by going lighter is if you start with an arrow that is grossly too heavy for a bow, like a 1000 grain arrow on a 30 pound bow.

Archery is a game of tradeoffs. A bow has only so much energy that it can store and give back to an arrow as speed, KE and momentum. If I were beaten back into a corner and had to say which arrow would penetrate best while giving the best trajectory per penetration potential... I'd be inclined to go to a chronograph, do what Mullaney does and shoot arrows in 50 grain steps from heavy to light, graph the speed and KE, then choose the arrow weight where the two lines intersect. And that weight is going to be somewhere in between the two ends of the weight scale. Between 6-8 grains per pound of draw weight, depending on bow design.

Start at the arrow weight on the graph where the two lines intersect and use that as your baseline arrow weight, speed and KE. Above the weight and below that weight, that's where you get into the tradeoffs. Does lighter/faster for slightly better trajectory but less KE and less momentum do more for you than baseline? Does heavier/slower but with more momentum, more KE and quieter shooting do more for you than baseline?


Twang, I see what you're getting at, just don't know for sure which direction you're going with it.

Edited by - Arthur P on 08/23/2002 07:43:23