Ozbow

Some years back I found a picture of one of these bows on the internet but no text to accompany it.

Whilst searching the net this week for bows incorporating a concave belly I found the following web site.

You may get the following alert.
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http://primitive-bows.com/hld-a-new-pro ... -selfbows/

Daryl.

Very interesting Daryl. If I remember correctly there was mention of concave bellies on bows in Archery: The Technical Side" by Hickman, Forrest Nagler & Paul E. Klopsteg. Some of the PNG bows made of bamboo had the concave on the back of the bow and not the belly. I think it would take some practice to make one of those bows he shows.

Jeff

Concave limbs can be tremendously beneficial to performance. However, when I see people scooping timber out of a wooden bow, I can't help but think they're doing themselves a disservice.

There was a fellow a few decades ago making laminated bows that had a concave belly. He did it with specially machined forms that pressed the lams into a measuring-tape shape during glue-up. These had better performace because the structure of the materials was altered to cause a given mass of material to become stiffer. Like tking a strip of very thin steel and bending it to look like a measuring tape.

However, when all you do it remove material to accomplish the same cross section, I strongly suspect this is functionally the same (mechanically the same, too) as making the belly convex. That is: crowning the belly. I've not yet seen it demonstrated that achieving the cross section through material removal has the same effect as deformation during lamination.

The convex-back bows are a different matter. This, I suspect, is more a matter of expedience (making bows from bamboo or palm) than the elusive hunt for an extra FPS on the arrow. There's no value judgement in this of course - just a suspicion based on the requirements of people needing to make reliable tools of sustenance with the materials and tools available. My uncle brought some back with him from when he was a missionary up there. They're truly remarkable and impressive weapons.

Yeoman

Dave,

I haven’t got around to making the profiling bits to try the following.

Daryl.

Don't ACS takedown longbows have a concave belly?

Yes, I believe that is the fellow who had the special forms machined up.

That patent has been taken over by (though not owned by) South Cox of Stalker stickbows - he bought both A+H and Dryad last year (I think?) and is now/about to offer limbs with the curved cross section options.

The Push have a podcast going through the whole shebang if anyone is interested - https://thepushpodcast.libsyn.com/episo ... -south-cox

metalhead wrote: ↑Thu Dec 23, 2021 8:09 pm Don't ACS takedown longbows have a concave belly?

Perhaps they were inspired by Howard Hill's patent.

Daryl.