# String walking: relationship between crawl length, distance and arrow velocity



## Hank D Thoreau (Dec 9, 2008)

This is the link to my previous post on gap aiming which is referenced above.

http://www.archerytalk.com/vb/showthread.php?t=854401


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## pilotmill (Dec 10, 2008)

*barebow*

Hank, thanks for the post, I play with this kind of experiments myself and enjoy your analysis, mine is not nearly as complete. I did take Archers Advantage and make a sight tape for my tab, just as a little test, interesting that the tape, reversed of course compared to my practice tab marks were right on. I am thinking here, does it matter if you adjust the front sight or the rear? 
Apparently not, mine is still work in progress, when I get a better idea of exactly how to input my numbers I will share but thats where I am going with my thoughts. Thanks again, Gar.


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## limbwalker (Sep 26, 2003)

Hank, that's pretty neat.

Chart doesn't match up with my results, but that's to be expected. Different anchors, different distances from anchor to eye, longer sight plane, etc., etc. will all affect the amount of string crawl at a certain velocity.

My setup is traveling about 190 fps. and I get a little less crawl than you do. But my arrows are 32.5" also... 

Keep up the good work! There is a method to our madness! ha, ha.

John.


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## Hank D Thoreau (Dec 9, 2008)

Thanks for the comments. The key is the relationships rather than the actual numbers (as long as the actual numbers are reasonable to validate the model). It is surprising that a parabolic trajectory would give rise to a linear string walk.

The parameters that I used do not match me either. I am tall and use uncut arrows -- and I have not had anyone measure my face while anchored. Still, it is amazing that the numbers are in the ball park. I have seen photos of folks using crawl lengths similar to the ones that are calculated. What I would be interested in is a plot of actual tab marks by shot distance to see if the linear relationship holds up under actual use. It seems to for me.


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## rasyad (Nov 22, 2005)

I am confused. Please clarify the term "crawl". I am finding 4 terms being used, "crawl legnth", "string crawl", "face crawl", and of course "crawling on the ground (as in stalking game) before "releasing the string".

Thanks, 

Rasyad


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## Hank D Thoreau (Dec 9, 2008)

In string walking you sight by holding the string at a different distance under the nocking point for each distance shot. The distance under the nocking point is chosen so that the tip of the arrow is on the target center. The crawl length is the distance under the nocking point that you hold the string.

Face walking achieves the same objective in a different way. In face walking (face crawl), you change the anchor point on your face for different distances.

Each of these methods is designed to move the position of the arrow relative to your eye so that the arrow tip can be placed on the gold.


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## rasyad (Nov 22, 2005)

Hi Hank, thanks for doing this work and for your clarification on crawling. The flatter trajectory that comes with faster arrows is easily grasped but I haddn't really considered the relative difficulty of estimating a gap vs setting a crawl legnth. 

Great stuff,

Rasyad


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## slhsxcmy (Sep 26, 2018)

This has helped me after 10 years, so I want to say thank you Hank.


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## f_thomas (Oct 12, 2006)

Answered above


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## Bender (Dec 6, 2006)

Hank there is this:

https://www.facebook.com/arch4archery/

FWIW Jim Conger there did find a small deviation from linearity at extreme crawls. 

Off hand it seems that it shouldn't be as linear as what either you or he shows. But that is surely because of the "hard limit" of point on. The trajectory is a parabola but to complicate matters even further, drag pulls the trajectory out of being a true parabola. (But that effect is most obvious at longer distances. )

Jim is a retired engineer from Boeing and it was with his help that I was able to develop and patent my high spin low drag Aero-Flight vanes. (they can be found here: https://www.fenderarchery.com/collections/aero-flight-vanes and some of my test data is here:https://www.fenderarchery.com/blogs/archery-info/aero-flight-test-data) He still had access to some sweet simulator programs for air foil profiles. (it's all good, he didn't care about holding the patent jointly) He and I met because we shoot the same events, and he came to me wanting me to provide "real world" data to fine tune his app. 

Oh and perhaps not so surprising, he and I found that when generating gaps or crawls, in the real world, the program is incredibly sensitive to distance from arrow nock to eye when at anchor.

Anyway, as odd as it seems, yep the linear relationship is basically supported, at least within "practical application" considerations. 2 people working independently came to the same conclusion. 

"I love it when a plan comes together" (insert mad scientist emoticon)


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## alish (Jan 31, 2018)

The linear aspect of crawl to distance is supported by personal experience. I can't remember where I had first read about this relationship, but the article showed how you could extrapolate crawl data to new distances. This was exactly what I did when I started stringwalking. I had only had the opportunity to figure out my crawls for 10-25 yds. when I decided to enter a local 3-D shoot (with marked distance targets out to 85 yds). I plotted the measurements down the tab (in mm) vs. distance to target, which was close enough to linear that it allowed me to determine my tab marks for distances from 25 yds. out to my point on distance (POD determined from the plot, not from actual field testing), and to guestimate new anchor locations for facewalking beyond my POD. I was pleasantly surprised how well it worked out at the 3-D shoot, at least out to about 65 yds. (I was shooting about 30# otf, so I had run out of lower anchors for longer distances). It was pretty funny trying to shoot the longer targets


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## slhsxcmy (Sep 26, 2018)

This is so helpful! Thank you so much!


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## liquidator4711 (Aug 4, 2016)

Bender said:


> Hank there is this:
> 
> https://www.facebook.com/arch4archery/
> 
> ...


Bender, it seems arch4archery is not available at the google play store and Jim doesn’t seem to respond to emails - any idea what’s up? Would love to try it out for outdoors.


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## BuzzMA (Jan 11, 2010)

I am curious about the vertical scale being used in the "gap" chart, specifically the units above and below the origin. Are the units above 0 vertical distances and those below horizontal distances and is this what appears to cause the non-linearity? Is the conclusion that since we are really bad at estimating elevation above and below the target "string walking" is the better choice, not that I would argue that it is not. It would seem that the down side to "string walking" is that since the measuring device, the tab, is relatively small, small errors have can have a large effect.


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## Humble3.14 (Nov 12, 2019)

I'm just looking for some clarity. 
Doesn't this show that string-walking is a sighted style of aiming, up to the archers point-on distance?


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## Seattlepop (Dec 8, 2003)

Does arrow speed (same kit) change as you crawl? More crawl less speed? Any calcs/charts for that? I've assumed this is the case from other discussions about changing spring tension for various distances when string walking.


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## equilibrium (Oct 31, 2006)

*I think this thread has the Corona #19 virus. *


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