RE: Who said that physics wasn't fun?
 

I don't think Arthur was suggesting that it would cure it, and I know I didn't. It's a step in the right direction.


Believe me, I don't want to soud disrepectful, but there are simply a host of reasons this might happen, and not indicate which will penetrate furthest on an animal. First, arrow tips must be identical shape and size, arrow diameters must be the same. They also both have to have perfect dynamic spine while being shot out of the same bow, and they should have the same percentage FOC. Here's the big one - the medium shot into, has to be of different densities which will tend to deflect the arrow. This is what happens when an arrow hits the edge of a bone or at an angle. The forces of defection have to be resisted. Heavier arrows will always resist these forces best. High FOC arrows will deflect less than low FOC arrows. This is the primary reason why tests into plywood and steel drums might be a good indication of broadhead strength, but have no real bearing on penetration potential in an animal.

RE: Who said that physics wasn't fun?
 

I may be thinking incorrectly but I don't see how this test couold be possible. Using the same arrow diameter and foc can be accomplished , but increasing the weight is not. That would entail jumping a cuople sizes up of the same arrow (i.e. Beman 400 to 300 to increase the weight enough to get 100 grs more) and keeping the diameter and foc the same by using the same fletching,tip,and nock, but the spine would be way off. Even if you could increase the weight of the shaft itself the spine changes.
You would have to get an arrow manufacturer to make 2 arrows w/ the same spine that were 100+ different in weight to run a test like this.

So I think we can conclude that spine and foc as well as mass and speed contribute to penetration. They are all functions in and of themselves. The variables(I don't believe) can't be eliminated.

RE: Who said that physics wasn't fun?
 

Every test I have ever done ( I have done many) always showed the heavier arrow penetrating better, but there is a sweet spot for most bows. And this was irregardless of arrow type or diameter.

I agree with almost everything Arthur and TFOX have stated except the thing about the thin walled aluminums. I get better penetration with 2213's than I have out of any carbon arrows I have used and certainly not any less than some of the thicker walled aluminums I have used. It won't matter how thin the wall of the arrow is, if it has the same spine it has the same resistance to bending. The diameter of the shaft makes up the difference for the thicker wall. So the only factor in penetration would be the larger diameter of the arrow. However in a well lubricated target like a live animal I don't think it would matter too much.

The thin walled arrows do dent easier though when you hit them with a different arrow.

I'm not saying one of us is right and the other is wrong, I just haven't seen this and I would need some pretty decent scientific evidence to the contrary to change my mind.

I have LOTS more to say about this thread, but I think I will bite my tongue for now. Those that know me know what I am thinking I'm sure.;)

Paul

RE: Who said that physics wasn't fun?
 

Dr. Ashby's results have showed better penetration with smaller diameter shafts.There has been some discussion that suggests all that is necessary is to have a broadhead ferrule that is larger than the shaft diameter - shaft meets little resistance with hole larger than shaft. He also demonstrates significantly better penetration with extreme FOC arrows. I'm not sure if he's said what shaft they are, but I'm willing to bet these are lighter weight carbons. I've tried building an aluminum with an FOC of 27-30% and adequate spine from a 70 lb bow, and have not been able to acheive it. Aluminum simply weights too much. I can't get enough weight on the tip. With carbons, I can easily get 350 grains on the tip of a relatively light weight shaft that is stiff enough to shoot it. These high FOC carbon arrows appear to out penetrate an equal weight aluminum quite easily, and I'm guessing that his statistics come from extreme FOC carbons. I do agree that this area of penetration hasn't been completely explored at this point.

RE: Who said that physics wasn't fun?
 

I will clarify I was speaking of deer sized game, not large african game.

Paul

RE: Who said that physics wasn't fun?
 

still going :D

RE: Who said that physics wasn't fun?
 

I know, I was thinking of stirring up all kinds of crap just to see if I could another 5 pages out of it, but decided to let it go;).

Paul

RE: Who said that physics wasn't fun?
 

Hey Einstein,

You are quoting someone else, as opposed to me....

RE: Who said that physics wasn't fun?
 

I used the same tip and put up 5- 1.5 spots on the target in diffrent places. If the shots were not within 3 inches of the 1.5" dot I disregarded it.

The lighter arrow has a smaller diameter. Your response reinforces my remark that there is a lot more that goes into it then just weight of an arrow or momentum. If I give enough examples you will just disagree with them anyway. Therefore, I'm done responding. I've proven my pont.

RE: Who said that physics wasn't fun?
 

I may be thinking incorrectly but I don't see how this test couold be possible. Using the same arrow diameter and foc can be accomplished , but increasing the weight is not. That would entail jumping a cuople sizes up of the same arrow (i.e. Beman 400 to 300 to increase the weight enough to get 100 grs more) and keeping the diameter and foc the same by using the same fletching,tip,and nock, but the spine would be way off. Even if you could increase the weight of the shaft itself the spine changes.
You would have to get an arrow manufacturer to make 2 arrows w/ the same spine that were 100+ different in weight to run a test like this.

So I think we can conclude that spine and foc as well as mass and speed contribute to penetration. They are all functions in and of themselves. The variables(I don't believe) can't be eliminated.
[/quote]

Thank you.

Does anyone know the record for # of pages in a thread?