Which design is quicker?

[cool_98_555]

Suppose you have two identical osage staves of the same length at 66", same growth ring pattern, same seasoning time, same character, etc.  The only thing that is different is the width you are going to use for both bows.  Let's say you had 1.5" wide on one bow (which would result in the limbs being more paddle-like and less thick), and one that was 1.25" thick (which would result in the limbs being thicker).  Which bow will shoot faster, provided everything else is the same?  Lets say both bows were just straight limb longbows with a stiff handle, so no reflex or recurve.  What do you think?  Would they perform equally?  Would they perform differently because of the width/thickness ratio?

[PatM]

They say with Osage and the like "thicker is quicker".

[sleek]

The thicker the limb the less it will distort on string release. Basically wasting energy and making it less effecient. Tje wider tje limb the less set you get. There is a balance.  Experience and mbow mass will get you very close. Badger is where I learned all this from, and a search of his name will do you wonders with information on his mass principle.

[cool_98_555]

This is interesting.  I've always thought to myself "hey, it doesn't matter what the width is, because if it is wide it will be less thick, but if it is narrower it will be thicker, so they are the same mass just with different designs."  Ironically, my narrower bows all shot faster than my wider bows, even if they had a bit more set.  Interesting eh?

[sleek]

It would seem the mass is the same but interestingly enough its not. There is an 8:1 ration in wood removal and poundage lost. A specific mass of wood removed from the belly affects the draw weight of a bow 8X more than were it to be removed from the sides. This allows for quick draw weight reduction and explains why bows are so flat. Then removing so much mass from the sides reduces mass drastically, which is why limb tips are so narrow and thick.

[Badger]

       The narrower bow would have to have more working limb, I do better with wider bows, I have added about 3 ounces of mass to my typical bows in recent years. I used to build most of my osage bows at 1 1/4" for 50# with a little reflex, now I am slightly under 1 1/2". Years ago I was building at 16 oz, I went up to about 18 oz and now I am at 21 oz. A good test is not which one of your bows is quicker, the good test is comparing it to a known quick bow. Anything over 175 fps is pretty quick for a self bow, anything over 170 I would give an A.

     There is only one correct thickness for any bow. It depends on the length, the width, the working limb area, the draw weight etc. It is up to the bowyer to figure out how to find that correct thickness. You can only do that by monitoring the condition of wood as you work or just go by experience which is what most of us do. Any set is bad, some is unavoidable but it is still bad, sacrificing working limb or width for lower mass is counter productive as far as I am concerned.

[SLIMBOB]

Twice as wide is twice the draw weight and twice the mass.  1:1 ratio.  Twice as thick is twice the mass at 8 times the draw weight.  8:1 ratio.  Thicker is faster per pound of draw weight because of reduced mass.  I cant swear that it actually works out to these numbers, but I believe it is accurate from a practical standpoint.
As mentioned, there is an "ideal" width for each bow that balances all these factors out.  Figuring that out is the fun part.

[bradsmith2010]

what badger said +1

[Stick Bender]

Interesting topic I think it depends on the design a lot of variables length of draw & weight etc , but I would say the one that keeps the string in front of the handle with the least set at decent mass is probably going to be the fastest , mass placement being more important then over all mass with in reason I have a longer draw so I find wider lower limbs holds a better profile for me even coming in at a heavier mass , speed comes in small baby steps and there is a negitive  return at some point mass wise .

[loon]

based solely on what i've read on tbb4. If you design the wider bow appropriately, without it being overbuilt (ie narrower and stiffer outer limbs), it could be faster... more stored energy and less limb vibration?

[George Tsoukalas]

Badger said,
"     There is only one correct thickness for any bow. It depends on the length, the width, the working limb area, the draw weight etc. It is up to the bowyer to figure out how to find that correct thickness. You can only do that by monitoring the condition of wood as you work or just go by experience which is what most of us do. Any set is bad, some is unavoidable but it is still bad, sacrificing working limb or width for lower mass is counter productive as far as I am concerned."

Excellent!

To add...

As I tiller I often need to narrow the width of the stave to bring home the tiller because the limb stops responding to belly wood removal.
Jawge

[PatM]

I've never seen a material that doesn't respond to thickness reduction. That seems like a paradox.

[George Tsoukalas]

Thank, PatM. I should have explained it better.
I meant  that the limb  begins to get too thin for my likes so I begin to narrow it.
Jawge

[SLIMBOB]

based solely on what i've read on tbb4. If you design the wider bow appropriately, without it being overbuilt (ie narrower and stiffer outer limbs), it could be faster... more stored energy and less limb vibration?

Your changing the parameters of the question.  I too think, like most everyone else who has built a few of these bows, that designing a bow properly is the key to performance.  I took the question as an academic one, "Is narrow and thick faster than wide and thin" all else being equal.  It (the narrow bow) will have less mass in the working limbs and therefore should return quicker.  But I see most of these things as trading away one thing to gain another.  It's a zero sum game.  As Badger and others have said, trading away mass comes at a cost.  Narrow and thick means more set at some point which will have a negative impact on cast, as will a narrow thick splintered back.  A bit wider and a little heavier would have solved that problem.  Length, width, mass, string tension and every other design detail needs to be balanced in order to work properly.  Too much of one things results in too little of another and problems arise.  Everything we do on these bows begins and ends with finding a balance with all these properties, or so it is for me.

[bradsmith2010]

balance is the key,, bottom line ,, you have pay attention as you go, and sticking to the original plan may not suit that piece of wood,,