Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: cunruhshoot on December 19, 2015, 12:53:00 AM
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Here is my question - does less deflex in a longbow limb increase the working portion of the limb as compared to more Deflex?
As I watched Dean Torges video - hunting the bamboo backed bow this is what I understood him to explain. If I am understanding correctly this would mean that my mild d/r design would be a bit slower than say the Kenny M form design that I also build from. But the mild d/r would throw a heavy arrow with more energy due to more working limb.
Here are pictures to compare my two designs.
Mild d/r
(http://i1073.photobucket.com/albums/w394/cunruhsurf/Bow%20Making/9588030b557a05cc7896f58a90e7f745.jpg)
More Extreme d/r
(http://i1073.photobucket.com/albums/w394/cunruhsurf/Bow%20Making/56325ed065e6619333c36fb6a352f37f.jpg)
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I believe more deflex causes more of the limb to work. That would translate into placing the mid limb posts closer to the riser at glue up.
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I've always understood the working limb to be the portion of the limb that bends, end of fade to nock.
The proportion of the total work done is less in the deflexed part of a limb than in the reflexed sectioned, reducing early string tension and concentrating the work done in the outer limb.
So less deflex means that the total work done by the limb is more evenly apportioned across the limb as a whole.
Just my understanding, I could be wrong!
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How's this for a selfbow FD curve. The working limb is less than 1/3 of the limb length. This is a flight bow by the way. The design goes against most of what we've learned as correct.
(http://tradarchers.com/forum/index.php?action=dlattach;topic=1503.0;attach=3347;image)
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Originally posted by BenBow:
The working limb is less than 1/3 of the limb length. This is a flight bow by the way. The design goes against most of what we've learned as correct.
(http://tradarchers.com/forum/index.php?action=dlattach;topic=1503.0;attach=3347;image)
The Siyah's are twice the length of the working part of the limb? A deflexed limb still works, it's still part of the working limb...
That F/D curve would suggest that there's a lot of early string tension which then pulls into a smooth draw. That would be a result of the string lifting off the string bridge/siyah's then the smooth draw is as it pulls 'normally'. But that initial 'heave' to get it off the string bridge/siyah's would explain the early tension.
I've recently reread the performance section of TBB1 - I believe most of this is covered in that.
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It doesn't change the amount of limb that is working. If it's bending it's working.
Do you mean what does altering deflex do to the stored energy?
Stored energy and efficiency are what matter when it comes to performance.
Narrow/thcker will return faster than wider/thinner Ben. Think of a tuning fork - which fork vibrates quickest when struck?