concave/convex bamboo longbow

[algstick]

can someone explain what concave convex is all about in regard to a bamboo hill style longbow?

thanks

[Roy from Pa]

Man ya lost me. Ya sure your not talking about deflex/reflex?

[jsweka]

It actually has something to do with the cross section of the limbs.  I think it's concave on the back, but I'm not totally sure.  Dave Miller is probably the only bowyer making these types of bows today.

[SportHunter]

I think the concave convex is a similar principle as trapping the edges to eliminate excess material and increase efficiency. Since the bamboo is curved its naturally concave or convex depending on which side of the bow its applied to.

Howard Hill had a patent on the concave convex design if anyone knows how to search old patents I'm sure it's out there, it has been posted before.

[LittleBen]

That would be where I step in ....

http://www.google.com/patents/US2256946?printsec=description#v=onepage&q&f=false

[LittleBen]

On another note though, I'm pretty sure that mathematically, the most efficient design always has a flat back and flat belly, the only thing that should be varied is the trapping to account for differences in the strength of the back and of the belly.