Who said that physics wasn't fun?
#131
Join Date: Feb 2003
Location:
Posts: 2,413
RE: Who said that physics wasn't fun?
Unfortunetly, I'm still not sure dictating a minimum weight will actually cure the problem.
I did an experiment today with my bow set at 66 lbs. I shot 20-391 gr arrows from 20 yds and 20-520 gr arrows from 20 yds. This may surprise you and the others here. But the 391 gr arrow's averaged penetration was 18.75 inches. The 520 gr arrow? 16.75 inches. That's 2 more inches. If people would like I'll keep track of this each time I shoot until I reach 100 shots with each and post. All shot at compressed sawdust particle board sheets.
#132
RE: Who said that physics wasn't fun?
ORIGINAL: Straightarrow
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.
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.
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.
#133
Join Date: Feb 2003
Location: Blissfield MI USA
Posts: 5,293
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
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
#134
Join Date: Feb 2003
Location:
Posts: 2,413
RE: Who said that physics wasn't fun?
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.
#139
Nontypical Buck
Join Date: Feb 2007
Location: Balt, MD (orig: J-town,PA) The bowels of Hell!!!
Posts: 2,188
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.
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.
#140
Nontypical Buck
Join Date: Feb 2007
Location: Balt, MD (orig: J-town,PA) The bowels of Hell!!!
Posts: 2,188
RE: Who said that physics wasn't fun?
ORIGINAL: archer58
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.
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Thank you.
Does anyone know the record for # of pages in a thread?