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Hornbow force/draw curves for Sleek

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bownarra:
Brace heights are 6 1/2 for the Turkish bow and the the other is braced at around 8 "

sleek:
For the second bow I got 93.45 joules, storing 95.74% of its drawn energy. Straight curve bows do give close enough to 100% so no arguments there. But I see this bow is 5% under the energy storage of a linear curve, not over it.
 Your numbers seem high. I added up all the numbers, to get inch pounds, then divided by 12 to get foot pounds to compare directly to his draw weight. I think perhaps a conversion discrepancy to joules may have contributed to an error for you?

Tuomo:

--- Quote from: sleek on February 13, 2021, 07:15:47 am ---For the second bow I got 93.45 joules, storing 95.74% of its drawn energy. Straight curve bows do give close enough to 100% so no arguments there. But I see this bow is 5% under the energy storage of a linear curve, not over it.
 Your numbers seem high. I added up all the numbers, to get inch pounds, then divided by 12 to get foot pounds to compare directly to his draw weight. I think perhaps a conversion discrepancy to joules may have contributed to an error for you?

--- End quote ---

I am not sure if I understand what you mean. I think that it is the US way to compare stored energy to bow's maximum draw weight, which is a bit vague way.

You get straight draw force "curve", when you draw straight line from zero to maximum draw weight. When compared to this "curve", these horn bows have much fatter curves. Straight draw force "curve" is very close to real straight bow's draw force curve, so that is why I compare other bow's stored energy to that. So, I define that straight draw force "curve" means 100 % or 0,5 or 1,0 or whatever, it is just a relative value to which I compare other values. I think that you compare stored energy to bow's maximum draw weight. And I do not understand, how it is meaningful to compare different units (joules to newtons, if using SI-units, or foot-pounds to pounds, if using imperial units). And, that is why I get readings like 110 %, because these horn bow stores more energy than straight bow to which I compare these horn bows.

Great bows, would like to try them, so maybe I have to make some! I have made just one Turkish horn bow, so not much experience yet. But measuring (and calculating...) is always fun!

sleek:
We compare how much energy is stored in a bow to the draw weight of the bow to determine how efficient the bow is at storing the energy we put into the bow by drawing it back. Its important because a bow that stores more energy compared to its draw weight has the potential to be a higher performance bow. The last half if that being it needs to also deliver its stored energy into its arrow as efficiently as possible as well. Both of those require knowing the ratio or the percentage ( your preference ) of the bows drawn weight to its stored energy.

I dont understand how you are doing it, or what information you gather thats valuable to you if you don't do it for comparison to the bows draw weight. Can you elaborate on your method and why?

Tuomo:
I got it. I am just comparing the stored energy to some kind of reference value, as you are also doing. You compare stored energy to bow's draw weight (SE/PDF), I compare it to stored energy under straight and linear draw force "curve" (then the stored energy is half of the theoretical maximum value). From the reference value it is easy to see, if the bow stores more or less energy than normal straight bow - the maximum draw weight does not matter. Of course, stored energy as joules is needed for efficiency calculations. So, stored energy can be presented as a reference value (percentage) or real value (joules).

I know that the reference value may be a bit confusing but it is still quite obvious when you are used to it.

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