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Sinew Backed, Double Curve Bow
M-P:
Hi Folks, From what I can find in the literature, Patrick is right in saying that the originals were shaped into the gull wing shape before tillering. A bow that is reflexed at the handle and straight limbed will also take a gull winged shape when strung. I think the second option increases perfomance by increasing early draw weight. See my example made from rocky mountain juniper
Ron
a finnish native:
what M-P said. you tiller the bow so that the wood bends from everywhere, and the handle being a tad stiffer will remain reflexed. I have to say that I have made several gull wing shaped bows. not for one have I defleced the limbs before tillering. it takes the shape automatically. And those bows of mine still contain reflex after several hundread shots.
El Destructo:
thats what I do to mine also....the Shape is pre-tiller
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JackCrafty:
Awesome! Thanks for the pics guys. ;D
It seems there are various interpretations of double curve (gull wing) bows. As for me, I try to focus on reproduction bows. After careful study of Native American designs, there seems to be one characteristic that stands out: Plains Indian bows are simply "curved" D-bows. They perform basically the same, and are tillered the same, as D-bows. The primary difference is the decreased brace height of the double curve bow design.
Any characteristic that improves the performance of a D-bow will also improve a double curve bow. Less deflex in the upper limbs is a good performance enhancer (as M-P mentioned) and so is recurved tips, narrowed tips, wider limbs near the handle, etc.....and there are Native American bows with these characteristics.
The reason(s) behind why Native Americans often liked to deflex the tips of their bows is a mystery from a performance standpoint.....but many NA bows have them, so I think they are an essential element.
IMO, a bow with a reflexed stiff handle and slightly reflexed, slightly deflexed, or straight limbs is simply a reflexed stiff handle bow. The design is efficient for long lengths but not for a compact bow....unless the limbs are quite wide. I would say that a reflexed stiff handle bow is more like a Sudbury bow than a plains double curve bow.
JackCrafty:
There is also the issue of the ability of the handle area to remain reflexed during the life of the bow. Many bowyers make the handle stiffer so that the reflex will not "pull out". Some woods are better at keeping this reflex than others. IMO, if you are using wood that does not hold a reflex well, it is not suitable for a double curve bow.
The way to get around this, of course, is to find a stave with the natural shape of a double curve...which is not too difficult if you've got thousands of acres of woodlands to rummage through. I don't know about you but I certainly don't. So...I've experimented with quite a few species and here is my list (best first) of suitable wood for double curves:
Osage
Juniper
Elm
Locust
Mulberry
Other low to medium stiffness, high tensile strength wood
White Oak
Hickory
White Ash
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