Question about bow poundage and arrow performance.

[Badger]

  Here is a good way to look at it.

 A 70# bow shoots 700 grains at 165 fps =42.27 KE
 A 70# bow shoots a 700 grain arrow @ 150 fps= about 35# KE
A 50# bow shoots a 500 grain arrow at 175 fps=34 #KE

 So the very fast 50# bow would be equal to the slow 70# bow.

[BowEd]

I see.Wonder what a 50# bow that shoots a 650 grain arrow at 165 fps is doing?Or same bow shooting a 450 grain arrow at 195 fps.Are these formulas in the TBB series somewhere?....lol.I should be able to figure this out myself.
It's not a matter of gain really to me it's understanding the process to see what is gained.A bow shooting with the comfort of a lighter weight bow but performing like a heavier bow is always desireable to me.The data gets turned into other things like a quicker kill and easier blood trail to follow.Not all exactly bragging type rights.Your taking my questions the wrong way.It's not just a target shooting type question.

[Badger]

Beadman, message me your e mail and I will send you a link for a kinetic energy vs arrow speed calculator. When you are making comparisons always assume that the KE will go up slightly as arrow weights are increased. So a bow getting 35# with a 500 grain arrow will proably get 38# with a 700 grain arrow because they get more efficient with more grains per pound.

[BowEd]

Well I went on this sight called toughhead arrowheads.Findings from Dr Ashby's research.1/2 mass times velocity squared or KE=[1/2M] X [V squared].He gets into momentum formulas too.V=[M] X [V].All of the arrow itself.Penetration diagnosis is done then too.
He gets into it really.Seems like just tweaking the front of center on an arrowshaft can increase penetration.Using less and less feathers for a lighter back end.

[BowEd]

Yes there is a calculator there that tells me my KE & Momentum.

[Pappy]

Man yall are making my head hurt.
 Pappy

[loon]

What I wonder is if momentum begins to matter more with massive sharp broadheads.. from reading their papers, it almost seems like momentum matters more. And mass even more.

toughhead... tuffhead?

[willie]

The data gets turned into other things like a quicker kill and easier blood trail to follow

Not trying to discount the bows poundage or the delivered FPS part of the equation, but when it comes to the arrows terminal effectiveness, I think that having a well tuned arrow, with some FOC, that delivers a straight-on impact, does as much for terminal performance as many of the other aspects under discussion.

[BowEd]

I knew about this tuffhead site too but did'nt realize they had a calculator right there too on the page.My mistake.Sorry Badger.
Dr. Ashby really gets into momentum being most important as far as penetration goes of broadheads Loon.I've got a friend here who's been shooting,tweaking,and experimenting with extreme FOC  shafts all summer long and says everything that Dr. Ashby said is true.Arrows fly like a dart.Using just 2" feathers too I might add.They are set up almost like a javeline.African tribes knew of this long ago using very long shafts with no feathers and big tall above man size bows.
He will hunt with an extreme FOC shaft this fall to see.Gary is wanting 2 holes in deer to have an easier blood trail to follow and since it's only a thinner skinned deer he will use those shark tooth broadheads.For now I will just stick with my dogwoods....lol.
Getting a 40# bow to penetrate with a broadhead as far as a normal set up shaft shot from an 80 pound bow.These are all 20 yard and under shots too.Grizzly broadheads have the best mechanical bone busting advantage also.So it's just not the bow to be efficient.The arrow shaft is all important too.For hunting & penetration that is and other uses also I'm sure.Hard to believe I know.If anyone is interested I suggest to read Dr. Ahsbys' findings.He is thorough.He tested on slain buffalo within 6 hours of being slain.   

[BowEd]

You bet willie.Your on point there.

[BowEd]

Seems like the discussion has drifted to arrow shafts...lol.,but still an efficient bow used is all important along with a properly set up shaft.I am in no doubt that 90% of the deer hunters out there are not using this advantage to hunt with.

[willie]

my experience with extreme FOC has  been that they do not yaw as bad, and consequently  can get by with less fletching, but there is a tradeoff with the extreme FOC not shooting as flat a trajectory. Good flight can be had with not so extreme FOC , if  you have trouble re-adjusting your range estimation, but a little more tuning is often necessary. Of course we do that with center balanced arrows anyways. There are also some arrow manufacturers spewing  BS about extreme FOC giving extra range....   

[bradsmith2010]

ok I thought about it,, yes a 50# bow shooting a 700 grain arrow 150fps is shooting the same as a 70# bow shooting a 700 grain arrow 150 fps,,
in the first Bowers Bible Tim says a normal 70# bow should shoot a 500 grain arrow about 177 fps,,we didnt do much 10gpp back then,the first mojam stats are all 500 grain arrow,,

I know things have changed a bit since then,, but in my mind,, that is still an ok shooting bow,,today we would expect it to shoot a 700 grain arrow 165 fps,,

[loon]

haha that is so slow wat, there's 50 pound bows that can shoot a 500 grain arrow at 180fps...
But I guess it'd still get the job done, I'd hate having to yank back 70# just for that though. And it's probably better to have a more accurate bow than a really fast one when hunting... I think accuracy and having the arrow hit straight are most important?

[Badger]

my experience with extreme FOC has  been that they do not yaw as bad, and consequently  can get by with less fletching, but there is a tradeoff with the extreme FOC not shooting as flat a trajectory. Good flight can be had with not so extreme FOC , if  you have trouble re-adjusting your range estimation, but a little more tuning is often necessary. Of course we do that with center balanced arrows anyways. There are also some arrow manufacturers spewing  BS about extreme FOC giving extra range....

  Extreme FOC will not change the trajectory anymore than just adding the same amount of weight anywhere on the arrow.