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Elasticity versus poundage

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BowEd:
Talk earlier on this thread was about how much work a core is doing.Think it was gfugal.I look at it this way.When 10% thickness of the limb on the outside[a backing] does 50% of the work yes the core is doing 50% of the work[one reason too for a decent ring on self bows] and 25% thickness of the limb on the outside[a backing] is doing over 80% of the work yes the core is dong around 20%  of the work too along with the sheer forces discussed.Quite a load off it already.With 35% thickness of the limb thickness[a backing] on the outside it is doing close to 100% of the work but the sheer forces strain will still be the same the way I understand it.Engineering minds come up with these findings of which I don't argue their point.The asians/indians/turks and other cultures figured this out long before PHD diplomas were handed out through trial and error I imagine.
That's why the 1/3,1/3,1/3 ratio of components they've shown are  ideal for horn/wood/sinew bow composites.This is old hat to those who have been making these but for someone new to it not and it's an explaination why it works so well.It does not mean though that is written in stone like Mike said but a good starting point.It can be 25%/50%/25% ratio too with very good results.

willie:
there seem to be many different composit designs out there, some with shorter working limbs than others. Wouldn't a shorter working limb have to bend into a tighter radius?, and consequently need to have a higher proportion of sinew/horn to wood?

seems like longer and easier bends could use more wood, although the trick might be to properly balance the sinew to the horn strengthwise, so that the wood remains centered about the neutral axis of the entire limb?

joachimM:
Willie, yes you see this actually, when examining cross-sections of different designs across the length of the limb.

But also bear in mind that moisture content management also makes a huge difference. Both horn and sinew strongly increase their stiffness from 12% MC (which is way too high for sinew-horn bows) to 4%. In my climate (temperate humid) I can hardly get to below 12% MC without a hotbox or similar.

willie:
waterbuffalo horn, from a buildalong at       
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the horn appears to be twice as thick as the sinew. I do not have adams book, so I cannot look it up for myself, but does he mention the relative strengths and working strain limits of the various horns and sinews?

BowEd:
joachimM is right I feel to a degree.Depending on what a person can live with.Most times actual turkish horn bows are sealed with layers of finish and paint and guilding also slowing the infiltration of moisture.Adam talks of using them in rain storms with no ill effect.Just part of the landscape owning one you have to put up with using natural materials.Mike lives in England and owns many.Very humid there.Although it can take twice as long to lose moisture as acquiring it in them.Horn is affected only in half the degree with moisture as sinew and glue will be so it's resiliency is better.
Putting the bow back into a say 7% to 8% MC warm setting over a period of a week from a few days of shooting[braced throughout] it would return itself to original profile it took after tillering.
willie...As far as different strengths of horn goes I believe he mostly was satisfied with water buffalo horns' strength and use.Some very early bows made from ibex horn.He talked of cow horn being too thin,twisted and having delamination problems of which I've seen for myself.Gemsbok horn is ok too if you can find some thick and wide enough.I have myself here.Sheep or possibly goat horn done by a few fellas on here make great horn sinew bows from it.Works of art.Chuck,Goat,and Redhand has one going too.I feel it could function in a horn/wood/sinew construction.Bahleen I would like to try also.I'm sure it's a lot denser then wood and could be used.
Sinew of most types is good as far as strength goes he feels.He preferred moose leg sinew.Did'nt like any backstrap as it being too course and hard.I feel Pat M's method of wrapping and heating helps eliviate this.Actually sinew will shorten when it swells.To dry and shrink to that state.I've used beef backstrap,buffalo backstrap,elk leg the most of,moose leg,and deer leg and backstrap.All are strong enough to use.As long as the grains of weight add up to being what you need.I have not used ostrich.Getting rid of the grease is the thing to watch out for using any.
I would say that the bow you saw with thicker horn depending on proflle of course would still have to have enough sinew on it to a thickness to stop any chance of splintering yet.
I can say in truth I shot the previous bow I made close to every day for close to 4 months straight for sure 6 to 8 hours a day bracing times in misty rainy days too[then unbraced overnight] with maybe 1/4" of set showing to the next day.With one full day of rest it was right back to original profile when first tillered.That's being stored inside the house then too inbetween shooting.Very little stress shown on these for the amount of reflex it held.Resilient.

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