I have read many post and agrued myself, the point of Kinetic energy being a better numerical representation of penetration than momentum. This last year I did a little experimenting during deer season. I had switched to carbon arrows which gave me almost identical KE and a little less momentum ( I have the number down somewhere if anyone is interested) than my trusty aluminums. I was shooting thunderhead 100, 28 inch CX 3D selects. The first deer I shot was a large doe. She was quartering away at 18 yards. the arrow entered a little to far forward and exited the far shoulder. From the angle of the shot and portion of arrow I found I can only speculate that the arrow must have stopped somewhere in the opposite shoulder. I do not take any pride in loosing a deer and I am embarrassed. It began to rain and the VERY POOR blood trail I had was lost. I returned the next day and look again. I never recovered the deer.

Disgusted with the poor penetration I switched back to my aluminums. Now mind you, identical KE and a more momentum. I had a shot a little buck with 2213' s and the same broadheads ( thunderhead 100). The arrow went through the opposite side shoulder. It passed through the large bone right where it joins the shoulder. While this again was not an ideal shot, the arrow passed completely through and stuck in the ground. The deer went about 50 yards. I thought about this all year and ended up killing another small buck with my bow. Complete pass through with my 2213' s.

While this is not a scientific test and under tight controlls, this was a practical application for me. I have come to the following conclusion.

Momentum and KE depend on the same variables, Mass and Velocity. KE is mass x velocity x velocity x 1/2. Momentum is mass x velocity. Since kenetic energy increases exponentialy as velocity increases, there could be a slight misrepresentation of actual penetration. Momentum is actually a vector. It is not simply a number. It is a number with a direction. As the arrow penetrates the deer, momentum is transfered to the deer. KE is afffected by friction as well as a transfer of energy. Since the friction can vary depending on the shot placement, angle on entry, surface of the arrow, etc, I don' t see how we can correlate KE and penetration. From my experience I think momentum might serve as a better tool to evaluate potential penetration.

I know this is opposite of what I argued last year, but I am big enough to admit, I could possible, sometimes, everyonce in a while, if the planets are aligned corectly, be wrong.

I would like to know if anyone else has some practical applications. Maybe we could come up with a test.