Black Stick

Alright, this is going to be hard for me to explain because I do not have a lot experience in testing arrow masses and their efficiency, but I'll do my best. Is it possible that the marginal gain in KE peaks. Think about it. Look at the following HYPOTHETICAL data:

365 grain arrow — 1# KE — _ Marginal KE
370 grain arrow — 2# KE — 1 Marginal KE
375 grain arrow — 3# KE — 1 Marginal KE
380 grain arrow — 4# KE — 1 Marginal KE
385 grain arrow — 6# KE — 2 Marginal KE
390 grain arrow — 8# KE — 2 Marginal KE
395 grain arrow — 10# KE — 2 Marginal KE
400 grain arrow — 13# KE — 3 Marginal KE
405 grain arrow — 16# KE — 3 Marginal KE
410 grain arrow — 19# KE — 3 Marginal KE
415 grain arrow — 23# KE — 4 Marginal KE
420 grain arrow — 27# KE — 4 Marginal KE
425 grain arrow — 31# KE — 4 Marginal KE
430 grain arrow — 35# KE — 4 Marginal KE
435 grain arrow — 40# KE — 5 Marginal KE*
440 grain arrow — 44# KE — 4 Marginal KE
445 grain arrow — 48# KE — 4 Marginal KE
450 grain arrow — 52# KE — 4 Marginal KE

It's like combining economics and physics into one very complicated question.

Black Stick

Because I could not post on the old thread, we will have to continue here.

A lot of time has been put into this question and I think it should be answered.

Sylvan, common man. Just do the tests. Seriously. Like Thumper's mother said in the Disney classic Bambi, "If you can't say anything nice... DON'T SAY ANYTHING AT ALL." The google searches, as credible as they may be, are not what I am looking for. NO MORE!

Everyone else, keep helping. I appreciate it. Thanks!

Black Stick

I am not here to prove or disprove scientific theory. I am here to get a question answered, so lets try to stay focussed.

Black Stick

I am just thinking that because it is highly unlikely for the KE/momentum to peak, maybe efficiency will. I certainly expect this to be the case. If you look at the HYPOTHETICAL data on my previous post, you would see that at 435 grains, the gain in KE Peaks at 5# KE. That is how I would define efficiency. I hope this helps.

Black Stick

I came up with this modified question thanks to Big Bulls post:

"If you calculate the numbers on the arrows that I posted you can see that my numbers agree with MeanV's findings. All three arrows were shot three times each through the same chronograph, out of the same bow, at the same draw length, at the same draw weight.

For poops and giggles I just shot a 397 grain arrow too.

397 grain arrow... 315 fps ......... 87# KE
443 grain arrow... 302 fps ......... 90# KE
502 grain arrow... 283 fps ......... 89# KE
625 grain arrow... 256 fps ......... 91# KE

Aparantly the 82nd, and probably the 101st, are less efficient with certain weight arrows."


Thanks!

Black Stick

Almoat forgot to remind everyone of my specifics:

30" draw length (29" arrows).

If you need anymore information, please, do not hesitate to ask, and again, let's stay focused.

Black Stick

I hope that with the help of the experienced members of huntingnet.com, we will narrow down the range of arrow masses, thus reducing my expenses for testing. Please HELP.

OHbowhntr

You're measuring KE now, not momentum, which is really ok for the most part if you are trying to achieve max KE, because max KE should have you carrying plenty of momentum to do the job on anything in NA. And unless you're planning on a trip to Africa, you'll be fine with just about whatever you place on that string, as long as it's above the recommended IBO weight. I think based of of some number crunching, it looks like around 500 ought to be hitting max KE based on some basic guestimates of your set-up, and if you were to drop weight to 65#, you max KE should be around 490, using "The Archery Hut Calculator," which I'll trust more than OT2 at this point. Question is what is the IBO on the Birth Certificate??? I used 340, as they always seem to come in low, and my numbers were hitting pretty close to what you posted. This calculator ( http://thearcheryhut.com/calculators.php ) is pretty close from everything I've used it on, and I'll go as far to say I trust it more than the OT2, which basically makes my purchase a waste of $25, but so goes life.

SwampCollie

I missed much of the first "discussion". I don't totally understand the question here... are you just wondering if KE as it pertains to arrows has a "Law of Diminishing Returns"..... as does certain Economic models?

JoeRE

You did not miss much for the most part[&:].

The heart of the argument is what happens to KE and momentum (do they peak?) when a particular bow at a particular poundage shoots a wide range of arrow weights....say from 300 to 700 grains. Is there a point with optimum momentum or KE as the arrow weight increases and velocity decreases or do they just increase/decrease within that reasonable range?

I am staying out of it entirely this time - I already know what I do know, and what I dont know[:-].