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Horn bows and stacking

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gfugal:

--- Quote from: mikekeswick on October 21, 2017, 01:52:42 am ---I draw my 48 inch Turkish bow to 30 with no real stacking and it doesn't show much string follow even if strung for a few days.
A standard length for a 28 inch draw Turkish bow would be around 42 inch. Of course you can modify any design to suit.
if you take the length of the bow and divide by 1.5 you will get its potential drawlength. So my 48 inch bow could go to 32 inch draw.   48/1.5 = 32.
Stacking in isolation is down to the design of the tips (angles) more than the length of the bow.

--- End quote ---

I concur that it's not just about length. If you have sharp angled recurves or siyahs you can avoid stack regardless of length as long as the material can handle it. It's just about making the right string angle and not related to the material bending. But if the recurve angle is low, or it's straight limbed I would stick to a draw around half the length maybe  less but I wouldn't go more than 1.8 unless you got some sharp and/or large levers such as in a Turkish bow.

sleek:
With time to have thought about this i realused there is another component to stack and string angle. I havent seen it mentioned but perhaps its already understood. Either way, i just recently realized it.

String angle is not what matters with stack. It is tip leverage and that alone. String angle is a bi product of leverage, not the cause of it. For example, the longer the bow the more leverage the limbs provide, as a result string angle is low at the tips.

Lets take this further. A short bow with standard recurves. Whats standard, I dont know dont be so difficult, just humor me. Now the recurves provide more leverage at the tips and as a result, the strung angle is low.

But lets complicate things. Why? Because I like to be difficult, and you arw still reading this so it must be ok with you too. Lets say for illustrative purposes only we have a short straight limb bow with no recurves. We know what to expect with string angle at its tips and stacking already regardless of how long the short bow is you just imagined. Now lets tie on a recurve the diameter of a basketball, and make it so the tip ends 90 degrees. When strung, the stack reduces as well as string angle. Lets now untie the basketball sized recurves and tie on soup can ones, same 90 degrees. All else being equal, the stack will increase compared to the basketball, even though string angle is identical. Now lets tie on a recurve the size of a golf ball. Once again all else equal, the stack will increase compared to the soupcan, but string angle is the same.

The take away here is, with tips, its a leverage function. With recurves, the leverage increases with radius. The string angle is just along for the ride.

Now the next stwp is to realose, there is an optimum radius and angle for any bow. Find that and you have a winning combination. Im certain there is a ratio or formula to be made to calculate the perfect tips for any bow.

gfugal:

--- Quote from: sleek on January 28, 2018, 01:32:15 pm ---String angle is not what matters with stack. It is tip leverage and that alone. String angle is a bi product of leverage, not the cause of it. For example, the longer the bow the more leverage the limbs provide, as a result string angle is low at the tips.

--- End quote ---
I think you're on to something sleek. Yes, we only care about string angle because it is related to leverage which is what really matters. I would have to disagree with you that string angle is a bi-product of leverage, but rather the inverse is true. Good string angle allows better leverage on the limb. However, like you mentioned it's not just string angle that can effect leverage. Lever length is also very important, if not more. So you could potentially have a better string angle on a short recurve due to its sharp bend but a longer lever in a siyah, for example, would produce more leverage despite having a worse string angle.


--- Quote from: sleek on January 28, 2018, 01:32:15 pm ---...lets tie on a recurve the diameter of a basketball, and make it so the tip ends 90 degrees. When strung, the stack reduces as well as string angle. Lets now untie the basketball sized recurves and tie on soup can ones, same 90 degrees. All else being equal, the stack will increase compared to the basketball, even though string angle is identical. Now lets tie on a recurve the size of a golf ball. Once again all else equal, the stack will increase compared to the soupcan, but string angle is the same.

--- End quote ---
This is some good creative thinking, again you're on to something. But I would have to disagree that it's the radius that matters. I don't think its the radius but the fulcrum length of the lever. a larger radius will naturally give a longer fulcrum, thus better leverage.

sleek:
I disagree very respectfully.  I believe it has everything to do with leverage and i believe I can prove it.

Simply putting the long post i made,  the bigger the gap in distance, between the string nock, and the back of the bow, the more leverage. It has ZERO to do with string angle.  String angle is a bi product not a cause of leverage.

sleek:
A bow could be built with tips thay shoot straight down, creating 0 degrees string angle,  and still have leverage as long as the nock is at or above the back of the bow.

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