Main Discussion Area > Flight Bows
Arvins 62" osage design
willie:
87.3 ntn 1" wide
I estimated some values for a thickness taper that produces equal stress for as far out along the limb as I could. you cant take equal stress all the way out to the tip. The resulting bend profile or shape plot is as expected for equal stress. Stress and strain go hand in hand.
Virtualbow is just a visualizer. The program does not calculate any limb dimensions for you.
It does predict stress and bend radiuses for whatever you input as widths and thicknesses, and will calculate the draweight once you supply a MOE for stiffness. and
It is up to the user to watch that the stresses do go too high and cause unwanted set, and the user will need to make allowances for any limb crossections other than rectangular.
woodbears spreadsheet works differently as you need to plug in estimates of the materiel stiffness and set a factor for limb crossection (round to retangular), a strain factor to hopefully prevent set, and an elasicity factor if you are working with a highly or lowly elastic wood, and some values for relative stress should you want stiff tips or a stiffer handle rather than a circular bendy handled bow.
Next you try various thickness tapers, and the spreadsheet will calculate the approiate widths to suit your givens. If you plug an impratical design into the spreadsheet it will simply show you that you are asking too much of the wood by outputting 6"wide limbs sections or some such.
bjrogg:
I have been trying to read all the information and it is very interesting. I haven’t really had enough time to do it justice but wanted you to know I am watching. (-P
Really neat project. I have to admit it’s probably a little over my head, but I understand the basic mechanics.
Like Arvin said the pictures are nice to study too. I like the idea of the project. I will be watching
Bjrogg
Selfbowman:
Well I locked myself off PA thank you Marie!!! She helps not so smart guys like me get back in!!! I have made progress . This is a shorter version of my longbow design. Here is where I’m at.
Bob Barnes:
Glad to see you made it back. :) I can't wait to see how this one turns out. I've always liked 62-64" longbows. :OK
Selfbowman:
Well after typing for 20 min I lost everything . 🤠🤠🤠I’ll try again.ok This is shorter version of my longbow design. 62” at this point. The stave had a pretty high crown in it. Here is width dimensions every four inches from center of bow. Pic
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