ATARNarchive

FD curve

4 posts2008live thread
Redhorse
An update on my first inner curve bow, one horn did explode :(
I had made some shooting at 27" draw and some scale readings at 28" belly. But in my last fd curve reading with a new digital scale it blows, I got only one reading at 27" and 80 lb. In the picture its the longest curve. My other shorter bow, the one from the inner curve tread is the one that readings start at 6" brace.
The other 3 (Puzio made) bows are weighted with old scale and not so exact but they show a little of were they could be in a more accurate reading. I can't be sure if my crono is correct but we get around 75% efficency most of the time. Sometimes higher and lower to, depending on how good the release was :)
The bows are close to Turkish and the Q is. what can we do to get more energy in the limbs and how to, get it out?
I guess this is something bowyers have worked with for millenniums :)
Adam Karpowicz
The f-d curves look about right.

For these short bows, the only way to boost energy storage is to add more overall reflex to the limbs. Then the initial "hump" on the f-d curve will be higher. At the same time one should rather avoid too much reflex in the kasan sections, because this would add mass to the limbs. It means the reflex should be more concentrated at the sal/kasan intersection to be straightened during the draw. Not an ideal situation, but a compromise. The efficiency can be improved by the reduction in mass for the tips and the kasans by making them narrower, but still sufficiently thick so they do not bend in the last half. Not too much width reduction, since the stability of the bow may suffer.

What is the "inner curve"?

Adam
Redhorse
Inner curve is the upper side of horn, the part that is up on the Buffalo horn. Normally the bottom side of the horn is what bows are made of. But after a wile you will have plenty of the shorter inner curve spread all over your shop :)
Learning the process of making a hornbow, they will do. And I have one that is made from the sidewalls of the horn. I think the sidewalls is what Dicks sell as hornbow slats.
Has anybody fd curve on crabbows and other types?

This is the bow that the horn did explode at scale :(
Redhorse
Nobody have f-d curve for other types?