GMMAT

When you start mentioning a part of the arrow that's being propelled from a bow "pulling" another part (upon impact).......you've overshot my engineering capacity.

Exit stage left...

Interesting, though

MO_Bowhnter

Well basically the arrow starts slowing down as soon as it leaves the bow string so the portion of the arrow with the most mass will have the greatest amount of momentum and this spot is the front of the arrow. So since it is slowing down and losing energy slower than the rest of the arrow, it must pull the rest of the arrow along.

Arthur P

Nowhere in the formula for KE does FOC show up.In my very best Jeff Foxworthy imitation, "Well DU-UH!" By the same token, nowhere in the formulas for computing aerodynamic stability does KE show up!You're talking two completely different things.

GMMAT

Who said anything about aerodynamic stability?

We were talking about penetration.

Duh.[&:](just kidding)

mobow

I don't see how a high FOC is going to impact how much KE an arrow uses upon entry of an animal. FOC is all about flight stabilization and how hard the fletching has to work at keeping the arrow on a straight path. As I mentioned, an arrow will flyheavy end forward. Period. Don't think so? Shoot an arrow that you KNOW is more heavy toward the nock end. I promise you it's going to flip over in flight. The closer your FOC is to 0, the harder the fletching has to work at keeping the arrow in a straight line.

Unless my thinking is completely warped, once an arrow enters the body of a deer, it HAS to follow the broadhead. KE and momentum are what moves that process along, not FOC. Again, FOC is allabout stabil flight.

BobCo19-65

Then why are we talking about KE?

JoeRE

Thank god for physics[8D]

What is being said is momentum is what really determines penitration for an arrow, it is the resistance to change of velocy/direction (meaning what keeps the arrow moving through an animal).

Without getting technical, strait line momentum of an arrow is greater w/ high FOC. (Moments of Inertia anyone[&:]?) Therefore, high FOC is preferable. How great of a difference does FOC have? That is the question....

Kinetic Energy does not directly relate to penetrating ability for archery although it does have useful comparative properties.

Arthur P

FOC is all about stable flight. But you have to consider that the arrow's flight is not done until it comes to a complete stop. In other words, it is still in flight during the time it's penetrating that animal.

High FOC allows the arrow to remain more stable and resist deflection when it contacts ribs and such while passing through. A low FOC arrow can deflect off a rib, causing the shaft to have more contact with the surrounding tissues, causing extra drag and reducing the arrow's penetration. If the arrow can keep it's KE and momentum going in a straighter line - more stable flight path - while penetrating, it'll penetrate deeper.

That's my theory and I'm stickin' to it.

PA Hardwoods

Thank you JoeRe! That is what I was trying to say but my brain and fingers aren't connecting today.[8D] Basically from what I understand Momentum is MUCH more important to good penetration than Kenetic Energy.

peakrut

http://www.huntingnet.com/staticpages/staticpage_detail.aspx?id=20
http://www.huntingnet.com/hunting/bow-hunting-resources.aspx
Our own HNI site info. Just a heads up, some other pretty good stuff in there.