RE: Does Kinetic Energy = Penetration?
About arrows flexing when they hit a target (which they ALL do, regardless of material)... You cannot take much from how an arrow acts when slamming into a target and going from XXX fps to a dead stop in a matter of a few inches. Granted, carbon arrows DO, in fact, dampen oscillation quicker than aluminum. No question about it. However, the slow motion video you see on the GoldTip website shows arrows hitting a target, expending all their energy and stopping dead with aluminums flopping around like a bullwhip and carbons just quivering. Impressive as all get out, but it's not all that meaningful. An arrow is not going to whip around like that when it zips through a deer's ribcage, so any advantage carbon's superior damping qualities give it are minimal in a real life hunting situation.
But then, use a heavy carbon that carries as much momentum as a heavy aluminum and you've probably really got something when that blasted shoulderblade gets in the way.
The more I think this over, the more I'm liking the idea of a heavy carbon arrow. Now to find one that works at an extra long length.