Power stroke?

[Kegan]

The ecent threads about selfbow speed mae me wonder: if an archer with a 28" draw is using a 6.5" brace height, and an archer with a 27" draw is using a 5.5" brace height, their power strokes are the same- so would their be the usual 5 or so fps difference in cast or not?

[knightd]

With my limited experience in this subject.. I find that all things draw weight and arrow weight and bow design being equal.. there should be no diference..

[Gordon]

You will get a little more energy because the string is pushing the arrow a bit further.

[knightd]

Gordon.. The power stroke is the same on the set up he is using...

[wolfsire]

With my limited experience in this subject.. I find that all things draw weight and arrow weight and bow design being equal.. there should be no diference..

I have a notion that this might not be correct.  If the bows are otherwise the same, they would have the same F/D curve but the inch in question would be on different parts of the curve.

[DanaM]

Good question kegan, me I have a 24" draw so at a 6" brace thats only 18" of power stroke
Maybe I should brace at 2" so I can get a 22" power stroke

[knightd]

I have a notion that this might not be correct.  If the bows are otherwise the same, they would have the same F/D curve but the inch in question would be on different parts of the curve.
[/quote]

I was trying to say if they were built for the given draw leangth.. With that said even if they were not !! the diference of 1" of draw and droping the brace to make up the diference should not efect the force draw curve enough to be that noticeable..
 There can be a Big !! performance diference in a bow designed for a 26" draw and one designed for 28" draw but only being drawn to 26".. I only draw 26" and I'm curently working on 2 or 3 design's specifically for  the 26" draw. That I and others have.. And yes I'm changing the F/D curve to work at that draw leangth..

[Marc St Louis]

If both bows had the same draw weight then the bow with the lower draw length and brace height will have the advantage

[knightd]

Mark I agree.. But it isn't much of a advantage at the given 1". and no change of design..

[Kegan]

If both bows had the same draw weight then the bow with the lower draw length and brace height will have the advantage

Can you explain that a little further? Is it just matter of less stress on the bow wood?

[Marc St Louis]

For one thing the bow with the shorter draw for same draw weight will have a more aggressive increase in draw weight per inch.  That means there will be a bit more push to the arrow throughout the power stroke.  Then there is the lower stress to the wood factor as well but that will not amount to much but the 2 combined will give the shorter draw bow a definite advantage

[Badger]

Probably the only real way to test this would be to take the same bow and lower the brace height and shorten the draw length. If done with the same bow the longer draw would win as it would have a higher draw weigth and store more energy. If you simply lowered the brace height and kept the draw length the same it would pick up a bit of speed. Steve

[knightd]

Mark I find that to not be always the case.. In allot of R/D bows the only thing that would change is the amount of string tension at brace but the bow will still only gain lets just say 2 1/2lbs per inch of draw. so the power stroke still remains the same..

[Kegan]

For one thing the bow with the shorter draw for same draw weight will have a more aggressive increase in draw weight per inch.  That means there will be a bit more push to the arrow throughout the power stroke.  Then there is the lower stress to the wood factor as well but that will not amount to much but the 2 combined will give the shorter draw bow a definite advantage

That makes alot of sense. Thanks Marc.

Steve- I meant two bows of same design, each built for the specific brace height and draw length.

[Badger]

Kegan, my lifetime fastest bow had a draw length of 26 3/4" and a brace height of 5". It started breaking down the wood as I increased the draw length past 27" and slowed down considerably after that. Steve