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Hair Brained Idea

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Re: Hair Brained Idea

Postby jwillis » Sat Feb 06, 2010 10:15 am

Bob, I think most of us are seeking a balance of shooting characteristics in our designs. One thing that the WTT building and testing is showing us is that the fastest and most efficient bows are usually also the best shooting bows. Some of us are not content to build what everyone else is building and be happy with that. We want to push the limits and see what is possible. Jim
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Re: Hair Brained Idea

Postby Kirkll » Tue Feb 09, 2010 9:52 pm

i honestly believe that the top bows this year will NOT be typical hybrid long bows. ;) once a guy figures out which design stores the most energy, and can harness the return into the shaft, and maintain good stabilty.....that's the guy that's going to pick up all the marbles. ;)
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Only archers are fool enough to want to make a composite with natural materials and man made materials, and then bend it repeatedly...
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Re: Hair Brained Idea

Postby DCM » Sat Mar 06, 2010 6:13 am

I'm hankerin' for a cigarette after that post Kirk.

I wonder if the question has been definitively answered:

When comparing two bows, will the bow that shoots faster at say 6 gpp always shoot faster at 16 gpp, all else equal of course? What about 8 gpp and 12 gpp?

I need to study this years results. You'd be surprised how much of what ya'll do finds its way into the mainstream in one way or another. And it all extends the craft.
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Re: Hair Brained Idea

Postby Crooked Stic » Sun Mar 07, 2010 5:52 pm

Yes.
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Re: Hair Brained Idea

Postby jwillis » Mon Mar 08, 2010 3:19 pm

I found it interesting when looking at the WWT3 results showing the FD curves and bow photos, that even though many of the bows had very similar unstrung profiles, and even very similar braced profiles...plus...even very similar full draw profiles...the fastest ones on the chrono visibly stored more energy on the FD curves and had no visible limb vibration at the end of the power stroke. Look at the FD curve on Kenro's 200 fps "Reaper" bow. It has very close to a longbow profile at brace and full draw, but has a FD curve that looks like a recurve. Other bows with less reflex had FD curves with a smaller hump. There must be some golden ratio stuff going on in that design in order for that to happen...finding the profile, layup, and selection of materials that provides the optimum power to weight ratio. We don't talk about that much. Jim
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Re: Hair Brained Idea

Postby badger5149 » Mon Mar 08, 2010 4:13 pm

David, the heavier you go with an arrow the more the speed will lean toward the bow with the most stored energy. The lighter you go the more they lean toward efficient bows. There will always be some place in the middle they shoot the same. Now if a bow stores a lot of energy and is also efficient it will win on both sides. Between 8 and 12 grains per pound you wont notice anything dramatic when comparing bows but it is enough to show the begining of a trend.
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Re: Hair Brained Idea

Postby DCM » Tue Mar 09, 2010 7:06 am

Steve,

Yes, I'm familiar with the concept, have seen the trend and have plotted hypothetical curves. But I wondered where or whether on actual bows the curves bows typically cross over, evidently above 12 gpp. It's been much discussed and ya'll do such a good job on data collection across a variety of bows I figured this presents an opportunity, attacking the old saw "the faster bow will always be faster" or more frequently "a longbow shoots a heavy arrow 'better'." Kinda like the long barrelled shotgun thing. While longer guns are "better" for long range pass shooting (waterfowl), it ain't because of the pattern density, retained energy or anything inherent in the gun itself.
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Re: Hair Brained Idea

Postby jwillis » Tue Mar 09, 2010 2:06 pm

What type of test do you propose? Shooting a range of arrow weights from a few bows? Or do we have to first find one that is really efficient and one that really stores a lot of energy? Or, do we shoot a range of arrow weights from a recurve, heavy r/d, mild r/d, and a straight bow? What is the hypothesis and what are the parameters? Jim
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Re: Hair Brained Idea

Postby DCM » Wed Mar 10, 2010 8:11 am

Well I should start by saying I haven't participated sufficiently to even suggest an agenda, but to answer your question the hypothesis is:

When comparing two bows, the bow which shoots 6 gpp faster will shoot 16 gpp faster.

Further, to be relevant to our purposes, a bow which shoots 8 gpp faster will shoot 12 gpp faster.

This premise manifests itself in all manner of antecdotes and philosophy like: Longbows shoot heavy arrows "better." Or the idea one should design a bow differently to shoot heavy arrows or, in Steve's case design a "flight" bow as if they two would not necessarily benefit in the same measure by the same design choices. I started to write "compromises" which is probably as accurate as I believe for each advantage you achieve in one area of performance you may sacrifice another.

As I understand the premise it is that a bow which stores more energy at the expense of efficiency (a heavy but pronouned recurve) will not suffer the same rate of degradation of speed over an increasing load (gpp) as a very efficient bow which doesn't store as much energy (a modest r/d bow with very tiny outer limbs). But in a practical sense, in the range of gpp we are interested in, does it matter? Another way to say if you plot the speed versus arrow mass of two (dissimilar) bows say from 6 gpp to 16, or 20 gpp, at what point if ever do the two plots cross.

Here's an example of the hypothetical plots to demonstrate the idea, speed on the Y axis, arrow mass on the X axis. But I haven't plotted actual bows which demonstrate this idea, and have argued over the years both sides of the issue.

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Re: Hair Brained Idea

Postby DCM » Wed Mar 10, 2010 8:14 am

"Bows designed for very heavy arrows as opposed to bows designed for very light arrows"

This comment of Steve's set me to thinking whether this idea (that the lines do cross in a range of gpp which is relevant to us) has been demonstrated by plotting actual data.
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