Request for those who are starting a new bow.

[Bayou Ben]

Steve, I'm sure you've come across this article....http://www.primitiveways.com/Bow_and_Arrow_Efficiency.pdf
I recently found it when trying to get more information about bow hysterisis. 
Are the results saying that the more you draw a bow the less efficient it will be?  So related to your experiment, a 24" draw may have 15% loss due to internal friction, where as a 28" draw would have 20% loss due to internal friction, regardless of set.  Or am I reading this wrong?
 
   

[Badger]

Steve, I'm sure you've come across this article....http://www.primitiveways.com/Bow_and_Arrow_Efficiency.pdf
I recently found it when trying to get more information about bow hysterisis. 
Are the results saying that the more you draw a bow the less efficient it will be?  So related to your experiment, a 24" draw may have 15% loss due to internal friction, where as a 28" draw would have 20% loss due to internal friction, regardless of set.  Or am I reading this wrong?
 
   

      I don't remember the kinds of percentages that were involved because they were all over the place with different bows. A perfectly designed and tillered bow would have hysteresis more similar to a fiberglass bow. Once a bow has been drawn past a certain point it can never be the same at that point again. The draw length is only pertinent once the set starts taking place. If everything is perfect it will react the same at 28 as it did at 24. The point is that once you have past 24 you can never go back and have the same performance as you did the first time unless everything was perfect. Most all 28" draw bows have at least some signs of set, some of them I see here are surprisingly fresh at 28" but I would still guess they have taken at least some set.  Thats why on my test I suggested we should an arrow at 24" when the bow has still never been drawn past 24" and then we go back after it has been drawn to 28" and shoot another arrow at 24" and compare the difference.

[DC]

So the old "man height" logic may be right after all. A six foot guy probably wants a 72" bow rather than a 66". It's strange that while bowyers were shortening bows they never noticed diminishing performance.

[PatM]

This is where a self fulfilling prophecy starts limiting things.

[Badger]

So the old "man height" logic may be right after all. A six foot guy probably wants a 72" bow rather than a 66". It's strange that while bowyers were shortening bows they never noticed diminishing performance.

   If the bows are wide enough and thin enough to take the bend they will do it. I tested one yesterday 50" long  50#@24"   I lowered it from 60#@24". I used the handicap method of lowering the grains per pound based on the draw length. It was hitting 182. This bow is really designed for very light arrows though in the 200 grain range. I think I was shooting about 410 grains.   As far as shorter bows taking more set and not performing as well. I think a good portion of them do suffer while some guys are able to handle it. Longer bows store more energy anyway.

[DC]

Shooting machine is about done. I've shot one arrow. I followed Del's lead with some of Jan's ideas. Scary rig to use. Should be back to bows tomorrow.

[Bayou Ben]

I have one that I’ll be finishing up in the next couple weeks. It will be a little overbuilt though at 28” as it’s designed for 29.5” draw.  Not sure if that matters.  I know it will take some set at 28” though, and going back to 24” will results in lower speeds.  So will this more or less quantify how much energy was lost to set?

[Badger]

I have one that I’ll be finishing up in the next couple weeks. It will be a little overbuilt though at 28” as it’s designed for 29.5” draw.  Not sure if that matters.  I know it will take some set at 28” though, and going back to 24” will results in lower speeds.  So will this more or less quantify how much energy was lost to set?

  That will be interesting. Just make sure your first shot at 24" is before it has ever been drawn past 24". If your second shot at 24 is pretty close to what your first shot is you know you did a good job on the bow. The draw weights will be different but the comparison should be the same because of adjusted arrow weight both times.

[Bayou Ben]

Okay. This sounds fun. Hopefully I will learn a thing or two in the process.  I may have to cut down some arrows.   I don’t think any of them are that light.

[Yellowstave]

So correct me if im wrong.. if performance drops off after 24", then wouldnt a person with a shorter draw length, lets say 26", have less loss of performance than a guy with 28 inch draw and therefore achieve greater cast??. 

[Hawkdancer]

I'm sort of in with DC, my draw length is 26".  A 22" arrow at 7.5 is no problem, but what weight at 26"?
Hawkdancer

[Badger]

I'm sort of in with DC, my draw length is 26".  A 22" arrow at 7.5 is no problem, but what weight at 26"?
Hawkdancer

   9.2 should work

[Selfbowman]

I think Alan makes the most since to me with his explanation. So most of our set occurs between 24-28" if we don't go past our intended draw weight in the tiller process? That seems to be where mine happens also just thinking back. So extra mass in width vs. set . Which robs cast the most? That's what I have been trying to figure out also. But I have not built that many yet.  Arvin

[Badger]

      Allen, I think you could equalize the test pretty well by ignoring the 28" shot and just comparing the before and after 22 or 24 inch shots made at the same grains per pound regardless of draw weight. I personally don't feel there is a good way to even the playing field by using a set formula to adjust weight. Lots of variables that doesn't allow for.

[willie]

     . I personally don't feel there is a good way to even the playing field by using a set formula to adjust weight. Lots of variables that doesn't allow for.

There can be a difference between a formula of "what is supposed to be", and a formula derived from actual shooting stats.