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Self bows with horn bow stats

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sleek:
You have my attention:)

Marc St Louis:
Unfortunately it was too long ago and I don't remember much about it.  I know it was a deflex static recurve but I don't remember if it was sinew backed or hard backed, I don't have the bow anymore

Badger:

--- Quote from: DC on September 16, 2016, 11:26:35 am ---I was just reading Tim Bakers "Bow design" chapter(around page 50) last night and I think he claims that the side profile of the "used and unbraced" bow will determine the energy storage. Doesn't matter whether it's all wood or sinew or horn, as long as the unbraced shape and draw weight are the same and the bow actually survives the bend, the energy storage will be the same. Are we disputing that?

--- End quote ---

  This is not true, pretty good indicator but a bow with plenty of reflex can have crappy performance. I built two bows a couple of years ago with about 12" of reflex and big recurves. It maintained most of its profile but the wood was basically crushed after a dozen or so shots and I had a mediocre performer, Thats why I now measure the draw weight at different points, sometimes a bow wont take much set but will loose weight.

loon:

--- Quote from: Badger on October 12, 2016, 12:26:25 am ---
--- Quote from: DC on September 16, 2016, 11:26:35 am ---I was just reading Tim Bakers "Bow design" chapter(around page 50) last night and I think he claims that the side profile of the "used and unbraced" bow will determine the energy storage. Doesn't matter whether it's all wood or sinew or horn, as long as the unbraced shape and draw weight are the same and the bow actually survives the bend, the energy storage will be the same. Are we disputing that?

--- End quote ---

  This is not true, pretty good indicator but a bow with plenty of reflex can have crappy performance. I built two bows a couple of years ago with about 12" of reflex and big recurves. It maintained most of its profile but the wood was basically crushed after a dozen or so shots and I had a mediocre performer, Thats why I now measure the draw weight at different points, sometimes a bow wont take much set but will loose weight.

--- End quote ---
Hence the *used* and unbraced reflex would be low? ie reflex right after shooting, then unstringing
Another thing that affects the energy storage is the tiller? How close to the handle the limbs bend? And I guess also where the reflex is, closer to handle or outer limbs. Of course you can also have a bow that stores a ton of energy that shoots horrible because it's very inefficient. Manchu bows are only great at very heavy arrows - long horn bows

gfugal:
The reason Horn Bows are so good is because of their shape and design that allows for earlier energy built up in the beginning of the draw. Theoretically if you built a self bow with the same design and it holds up it would perform similarly. However, there are two problems. 1) Self-bows usually can't take that much energy without breaking or getting set. I am finishing up on a another short wood bow with only paper backing. Its 43" knock to knock and draws 45#@27". That being said it has a horrible energy storage curve because the wood just can't handle the design. It got a lot of set and string follow. If a wood bow was to compare to a horn bow it would have to be able to retain the large reflex without taking set. Now this could be because I'm using less than Ideal wood and errors in my tillering, but it still illustrates the problem. 2) the other issue is even if you were able to get the same force curve as a horn that doesn't mean it will spit out an arrow at the same speed. Some material is less efficient at transferring potential energy into kinetic energy. The only way to know is to get the efficiency ratio by taking the kinetic energy determined by the velocity and arrow mass and divide it by the stored up potential energy determined by the force curve.

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