F.O.C. / broadhead weight (moved)

[Terry Green]

Originally posted by Str8Arrow:
If you read Ashby's studies, you'll see that momentum is more easily redirected when it is centered further back on the arrow. Even without doing the studies myself, it makes perfect sense that an arrow that deflects more (lower FOC), will not penetrate as well as an arrow that deflects less (higher FOC).  Add in the penetration measurements taken from shots from the 40 lb vs 65 lb bow and it makes sense.

I sure don't see that in the momentum aspect...maybe there's some contradiction there???

1st a person claims momentum is king, and then he does not?  Again...where is the facts or proof.  Where are YOUR tests not someone else's?  I've done my own....and on LIVE animals and 3 different target mediums.  I cannot find where a 45# bow exceeds a 65# bow at 10 grains per pound period.

Now show me the proof....YOUR proof, not someone else's 'theories'.  The momentum numbers don't lie, and neither do momentum vs FOC.  Show me EXACTLY where I'm wrong.....without smoke and mirrors.

SHOW ME where a 45# bow with 25% FOC exceeds a 65# bow same grain per pound with the 65# bow at 15% FOC with the same design bow and draw length.  PROVE IT to me....not theories about it.  PROVE IT. I'd love for my 70@ bows to 'hit like' 90#ers.

[Str8Arrow]

Originally posted by Terry Green:

1st a person claims momentum is king, and then he does not?

I'm not sure who said it was king and then said it wasn't. I say that momentum is a better indicator of penetration potential than KE is. Potential of course, can be unrealized - especially if redirected by a bone.

 

Again...where is the facts or proof.

Ashby has provided a huge amount of data that supports his theories. Like I said, proof is not going to happen - not on the internet.

 

Where are YOUR test not someone else's?

I've done no formal testing with data that was critically analysed. All I have is 5 years of shooting High and extreme FOC arrows into animals with very positive success.  However, there is nothing wrong with relying on the substantial testing done by Ashby.

 

I've done my own....and on LIVE animals and 3 different target mediums.  I cannot find where a 45# bow exceeds a 65# bow at 10 grains per pound period.

Point me to the data so I can see if it make sense to me.

[Terry Green]

All I have is 25 years of KILLING animals with 18% FOC with GREAT success....and measuring penetration in 3 different target mediums with different weight bows.

   

Originally posted by Terry Green:
     

Originally posted by Str8Arrow:
If you read Ashby's studies, you'll see that momentum is more easily redirected when it is centered further back on the arrow. Even without doing the studies myself, it makes perfect sense that an arrow that deflects more (lower FOC), will not penetrate as well as an arrow that deflects less (higher FOC).  Add in the penetration measurements taken from shots from the 40 lb vs 65 lb bow and it makes sense.

I sure don't see that in the momentum aspect...maybe there's some contradiction there???

1st a person claims momentum is king, and then he does not?  Again...where is the facts or proof.  Where are YOUR tests not someone else's?  I've done my own....and on LIVE animals and 3 different target mediums.  I cannot find where a 45# bow exceeds a 65# bow at 10 grains per pound period.

Now show me the proof....YOUR proof, not someone else's 'theories'.  The momentum numbers don't lie, and neither do momentum vs FOC.  Show me EXACTLY where I'm wrong.....without smoke and mirrors.

SHOW ME where a 45# bow with 25% FOC exceeds a 65# bow same grain per pound with the 65# bow at 15% FOC with the same design bow and draw length.  PROVE IT to me....not theories about it.  PROVE IT. I'd love for my 70@ bows to 'hit like' 90#ers. [/b]

Again...PROVE ME WRONG....PLEASE!!!!!!!!!!! I want my 70#ers to 'hit like" 90#ers please prove it to me!!!! ( I don't think you can)

[Str8Arrow]

Why are you so hung up on this "prove me wrong"? Don't you know that nothing can be proved absolutely? Do you realize there is a whole segment of society that believes the earth is flat and you can go to their web forum and I'll guarantee you that you will not be able to prove to them that it is not.

I'm not asking you for proof. I'm asking you for data that I can analyse critically. I want to see if your testing was complete or if you missed something or made an error or two in your testing or conclusions. After reading Ashby's studies, I was very impressed by the thoroughness of the data and conclusions drawn. I'm really hoping if others have contradictory data, that they simply let us study it.

[Terry Green]

Originally posted by Str8Arrow:
You just asked the poster before you for proof.  Where's yours?  

Originally posted by Str8Arrow:

I'm not asking you for proof.  

Looks like more contradiction......

Until it is PROVEN....I stand by my signature line...Until then, I'll be waiting for a common sense answer.

[Str8Arrow]

Sorry....I meant to quote you but edited your post by mistake.

[JimB]

A lot of people don't realize that perfect arrow flight is near the top of Ashby's list in order of importance.

He says,"Poor flight squanders arrow performance.
  You should spare neither effort nor expense in achieving absolutely perfect arrow flight.Even with every other factor in place,without good arrow flight you'll still have poor arrow performance."

[Terry Green]

Originally posted by JimB:
A lot of people don't realize that perfect arrow flight is near the top of Ashby's list in order of importance.

He says,"Poor flight squanders arrow performance.
  You should spare neither effort nor expense in achieving absolutely perfect arrow flight.Even with every other factor in place,without good arrow flight you'll still have poor arrow performance."

Amen....LOTS of folks here are preaching that as well....and have been for a LONG time.

[Str8Arrow]

I agree. EFOC is only a part of his studies and recommendations. In fact, he recommends shooting the heaviest draw weight you can accurately shoot at hunting distances. Even though his data demonstrates that you can optimize an arrow's penetration with EFOC, he's an advocate of using as much fire power as possible. He'd like you to shoot the heavy draw weight with the optimized arrow. One of his beliefs is that there is no such thing as too much penetration when bowhunting.

[Terry Green]

Originally posted by Str8Arrow:
[I see, in other words, you have no data to suport your view and want to protect the unknowing masses from the only data given in a thorough study on the subject.  This is good to know. It explains a lot. end quote.

What speak volumes is YOU have no proof OR data.....nor can prove me wrong even though I HAVE data.  I GAVE it to you....PROVE to me the 45#/65# claim...with DATA.

[trcytylr]

I just wanted to tune my little bow and arrows   :(

[mrjsl]

Originally posted by Str8Arrow:
Why are you so hung up on this "prove me wrong"? Don't you know that nothing can be proved absolutely?

E = mv2/2

Isaac Newton and the prevailing laws of physics are on Terry's side here.

I had never heard of EFOC until a month ago when I dusted off my recurve and set about trying to tune things up.

However, the idea that you can take two arrows traveling at the same speed (for arguments sake) one 650 grains, and one 450 grains (roughly 30% lighter) and achieve the same impact energy by shifting the weight distribution of the arrow is... poppycock.

It may improve arrow flight in some arrows, thus aiding penetration somewhat, but that is not what was claimed.

This can easily be tested. Take the two bows and the two arrows. Use rubber blunts and shoot them at your car and check the size of the dents. No matter what you do to the FOC the heavier arrow + heavier draw weight bow will make a bigger dent.

[Ragnarok Forge]

Ok,  I think were missing some critical points in this discussion as it revolves around my earlier statement.  My statement was based on penetration optimized arrows for the 40 lb bow compared with standard nonpenetration optimized arrows with the 60 or 65 lb bow.  If you give the Ashby reports a thorough read you will see that this is their basis for research and reporting.  

Optimized arrows do not weight 10 gpp.  That number has nothing to do with the Ashby reports or arrow optimization.  Ashby uses standard, high and EFOC arrows that weigh over 630 grains in his testing. He uses arrows that are  optimized to allow for the best penetration possible, and similar weight sets that are not optimized.  All shot testing is on recently killed animals.  These arrows are tested against each other.  

I work as an engineer and have reviewed his numbers, his theories and their basis, and torn his entire process and practices to pieces looking for flaws.  There really are not any to be found with minor exceptions that don't change the results of his studies.  


Terry is 100% correct, if you shoot the 10 GPP arrows for both bows the light arrows don't even come close to mathching penetration of the heavier bow.  If you take a non optimized 650 grain arrow out of a 65 lb bow and a totally optimized 650 grain arrow from a 45 lb bow, your gonna be suprised at the results.  In most  cases the lighter bow will match and at times exceed the heavier bows penetration.  Ashby's testing supports this as well.

Terry you will never get your 70 lb bow to shoot like a 90 lb bow, the arrow weights are roughly the same so the arrows arc will be different between the two bows.  You can get the lighter bows optimized EFOC arrows to penetrate like the heavier one when it is shooting standard design FOC arrows.  

Ashby's testing is indicating that EFOC arrows are showing dramatic increase in penetration over standard arrows.  Terry is right here too.  10% more more FOC helps a bit.  20% more FOC makes a lot more difference than we all think.  I am excited to see how much in the next few Ashby reports.

My engineering based review of all this stuff, the laws of physics, and momentum equations as they apply to penetration all lean to EFOC and penetration optimization of your arrows as a great way for a light weight bow shooter to bring their penetration to a point where it will match a heavier bows using standard non optimized FOC arrows.

Important to understand that I am not arguing with anyone here.  I think the original poster was asking about FOC and how to tune for it.  Drop me a PM and I will be happy to tell you how I did it.  Terry has a great post or two on how to get there so search a bit and find them.  Those posts saved me a ton of work to find EFOC.

[Ragnarok Forge]

The momentum equation which is what defines the energy that is used by an object to achieve penetration does not square velocity which is where the KE equation fails as does the one noted in the thread above.  The statement that physics supports Terry's comments is correct.  Since Terry's statement covered different weight arrows instead of optimized arrows for one bow and standard arrows for the other.

[Terry Green]

mrjsl ......thanks.....haven't heard the work poppycock in a long time.

Yep, run the numbers over and over and over, ....they don't lie.

Someone got 'hung up' on when I said 'I feel'...and that comment was ONLY directed to what I feel is minimum FOC for broadheads and hunting....had nothing to do with the facts I stated above that statement.

Here we go again....

"If you take a non optimized 650 grain arrow out of a 65 lb bow and a totally optimized 650 grain arrow from a 45 lb bow, your gonna be suprised at the results. In most cases the lighter bow will match and at times exceed the heavier bows penetration."......                     Run the momentum numbers on those two arrows....too great to overcome with a simple weight distribution shift on the arrow.

OK......this one has run its course....back to hunting...