[blakey]

Just wondered if anyone has any experience or advice about tuning for stringwalking with the super curve limbs. I'm kicking around buying a set, because I'm impressed with the speed I've seen at the club, but the ones here are all Olympic recurve with positive tiller. If I buy a set for stringwalking, then the crawls are going to change the lift-off point of the string under the bottom limb. Is that going to create a significant problem? I wonder if it might emphasise tiller imbalance, which is already challenged by the tune anyway? What do you think?

 

[Flying Watchmaker]

My wife string walks with hex5's, xs on 25" (bought before we found out about string walking), but they still work well, we tune(ish) for around 35m, and accept the inefficiencies at the extremes, used for everything from 5m bugs field targets to 70m fita rounds..

At some crawls they definitely don't sound nice, but still group well!

Tom

 

[Matt_Potter]

I string-walk Hex-6 limbs and love them. I think the extreme vertical stability of the design handles the effects of string-walking better than traditional profile limbs.


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[Rasyad]

Hex 6 BB2 here as well. I think there are advantages to the super recurve shape for stringwalking. We know that the smoothness of SR geometry happens because the limbs unfold and the string lifts off the limbs (out of the string groves) right before anchor. This creates extra leverage on the limbs and reduces the rate of draw weight increase to less than 1.4 pounds per inch whereas conventional limbs are more like 2-4 ppi at anchor.

As I understand, stringwalking has two main tuning challenges. The first is the increasing downforce on the rest at longer crawls. Fixes for this include tiller changes (depending on the target tuning distance and mystery form issues), high nock point, and matching the flexibility of the rest wire to work with everything else. (too stiff and the arrow bounces off the wire, too soft and the wire bends and fails)

The second tuning challenge is horizontal (left-right) consistency at all distances. With longer crawls the effective draw length is reduced which lowers the total energy imparted to the arrow. This causes the arrow to fly stiffer at shorter distances and weaker at longer distances. Fixes for this include aiming off to compensate or using the plunger spring tension to compensate.

Here is where the smoothness of super recurves helps. A 1/2" DL change with a really long crawl only reduces the draw weight by 1/2 # or so. The total power stroke is also reduced with longer crawls but the smoothness still helps. As well faster arrow speed and flatter trajectory are good things with stringwalking.

I have a theoretical question. We know that as limb tips unfold the bowstring is essentially "let out" and the unsupported string length grows during the draw. Upon release the first thing the limbs do is "reel in" the string and shorten the free string length.
With long crawls there is uneven string length above and below the arrow nock. Upon release the "slack" in the lower string has to be taken up as the arrow is being launched. Might it be possible that Super Recurve limbs do a better job of this compared to conventional recurve limbs or longbows?

Rasyad

 

[rsarns]

I have a theoretical question. We know that as limb tips unfold the bowstring is essentially "let out" and the unsupported string length grows during the draw. Upon release the first thing the limbs do is "reel in" the string and shorten the free string length.
With long crawls there is uneven string length above and below the arrow nock. Upon release the "slack" in the lower string has to be taken up as the arrow is being launched. Might it be possible that Super Recurve limbs do a better job of this compared to conventional recurve limbs or longbows? Rasyad

That's a very interesting idea, but my first reaction would be the opposite, as the string has further to travel with the big curves that unfold as they do. I am not a physicist nor have a clue..LOL Would be an interesting slow motion video comparison.

 

[Rasyad]

Ren,

My thinking is that the string "slack" has very little potential return force (accelerating the mass of the string) compared to the maximum stored energy of fully drawn limbs the dynamics of which demand that the spring force is focused at the limb tips.

I agree that high speed video will be the way to study this. I spoke with Dr. Dennis Chan at UC Berkeley a couple months ago. His department is buying new high speed video equipment and he is hoping to look at arrow clearance dynamics of super recurve limbs. I have offered my bow as a test subject. If this happens we should also be able to look at issues related to stringwalking.

Rasyad

 

[Sid]

Wow. Rasyad.

We would be mega keen to hear what others think on the impact limb stiffness has on paradox. We have our work. But third party findings would nock our socks off...
We have apporached a couple of experts in the field and recieved little to no room for a discussion. But then again some of them have spent alot of time refineing there models. Who wants to hear someone say there might be more to it.

Im not intending to blow our own trumpet here... but choosing a spine with the covert is more complex than ever.... it shoots alot of arrow setups with credability.
We think this is due to the string being supported more in string grooves. And this helps control left right nock movement. Which is also a trick that helps SW.
We have said before that the more you rely on the limbs cam action the more it will be effected by stringwalking. But there is more to bow tune than limb timing... vertical string stability. As well as horizontal string stability. This latter one is very complex

 

[rusty craine]

Well I am a believer. Go out 60 yards and put an aiming point above the target so you hit the target shooting with a one and half inch crawl. Gather up all the limbs you want to test and shoot away.

It will not take long shooting 60 yards with a 1.5" crawl for the limbs to sort themselves out. Especially true if you are a middle of the pack shooter.

 

[Jon Lewis]

I have seen no evidence that big curve limbs are any better or any worse for stringwalking, face walking or even moonwalking. Matt does ok with his, John, Jason, Scott, MartinO etc do ok with normal limbs so you pays yer money you takes yer choice I say.


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[Matt_Potter]

Well I am a believer. Go out 60 yards and put an aiming point above the target so you hit the target shooting with a one and half inch crawl. Gather up all the limbs you want to test and shoot away.

It will not take long shooting 60 yards with a 1.5" crawl for the limbs to sort themselves out. Especially true if you are a middle of the pack shooter.

Rusty

What's your point on if you can use a 1.5 inch crawl at 60 ???

Matt

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[rusty craine]

I am forcing the issue. My point on is 47 yards. At sixty yards I shot at the target with 1.5" and gap over the target till I can group the arrows.

It is a somewhat artificial test to see if one set of limbs will group better shooting from a more difficult release to get perfect.

 

[Sid]

I have seen no evidence that big curve limbs are any better or any worse for stringwalking, face walking or even moonwalking. Matt does ok with his, John, Jason, Scott, MartinO etc do ok with normal limbs so you pays yer money you takes yer choice I say.

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i dont think the subtlety of this has been noticed...

recurves of half the size of something like a hex limb used to be regarded as large recurve, were also regarded as nervious to shoot.

now they are being reported to be equal. But hugely bigget than big has been regarded