Author Topic: Difference between Bow woods for performance?  (Read 6658 times)

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vCo2v

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Difference between Bow woods for performance?
« on: November 14, 2008, 05:31:09 pm »
My main question is there a difference in performance between a Hickory English Longbow at 50# to a Bamboo/Ipe English Longbow at the same draw weight?

and for the same draw weight what would perform the best or would it even be a noticeable difference? Because there seems to be many different combination of woods.

Bamboo Backed Ipe Belly Bi Laminate

Bamboo Backed Ipe Core Hickory Belly Tri Laminate

Bamboo Backed Ipe Core Hickory Core Ipe Belly Quad Laminate

Offline Badger

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Re: Difference between Bow woods for performance?
« Reply #1 on: November 14, 2008, 05:49:23 pm »
I think the most important thing is that you design your bow around the wood you are using. A full compass tillered 50#  boo/ipe bow 72" long would likely be too narrow to be stable or too heavy to be efficient, ut thta said a 50# hickory/ ipe elb broke some flight records last year, but it was only about 60" long. Design is everything, far more important than the wood species. Steve

GraemeK

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Re: Difference between Bow woods for performance?
« Reply #2 on: November 14, 2008, 06:20:01 pm »
The problem is your question is too wide ranging and there are too many variables to be able to give a simple answer.
Below are a few but not all of the considerations.
In most woods the strength is proportional to the density so with a correctly designed bow for the timber it should be possible to get similar results.
Unfortunately once you start to impose specific styles on woods -- say ELB -- then you have committed yourself to a design that may not suit them, and in fact a traditional ELB is very hard to get to work as well as it should with any other wood than Yew because its design needs a low density but stiff timber and Yew is about the only really good one.
The timber choices you mention present their own set of variables -- the hickory will only perform well if it has a suitably low moisture content and has a typically lower ratio of strength to weight than Yew and the  Ipe / boo combination probably has a similar ratio of strength to weight but a much higher density so in an ELB design you end up with a fairly narrow thin bow that is unlike a traditional ELB.
The question about the different styles of laminated bows is best answered by explaining why people choose to laminate bows at all. The first choice is to glue 2 woods together to try and get a backing wood that is high in tension strength and a belly wood that is high in compression. the second choice is to add a third lamination in between them that is light to try and reduce the mass of the limb. After that any more lamination's do not serve any great technical purpose and are more likely to be the result of construction technique.  

I guess the best advice I can give you is that you could get a satisfactory ELB "style " bow from any of  the combination's you mention or from Hickory and the greatest differences you will see from one bow to the next in terms of performance will be the skill of the Bowyer.

Graeme
 

GraemeK

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Re: Difference between Bow woods for performance?
« Reply #3 on: November 14, 2008, 06:22:19 pm »
Hi Steve
You are so much more succinct than me -- and I did not check  the new post before I sent mine --- GKL
« Last Edit: November 14, 2008, 06:59:28 pm by GraemeK »

Offline sailordad

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Re: Difference between Bow woods for performance?
« Reply #4 on: November 14, 2008, 06:24:16 pm »
i disagree with badger

my boo/ipe elb is 72" tip to tip,just checked it last night on the scale,60lbs @ 29",shoots fast( i think),light weight,but i do agree with badger on
the fact that you should dwsign your bow around the woods that are being utilized.

personnaly i like ipe more than hickory,personnal preference. ipe you can keep them thinner,narrower and lighter weight
i always wanted a harley,untill it became the "thing to ride"
i ride because i love to,not to be part of the crowd

vCo2v

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Re: Difference between Bow woods for performance?
« Reply #5 on: November 14, 2008, 06:28:19 pm »
Wow.... That read just blew my mind away

Apparently there is a lot more to wood in bows than I would have thought.

Thank you so much for the great insight

Offline Justin Snyder

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Re: Difference between Bow woods for performance?
« Reply #6 on: November 14, 2008, 08:34:02 pm »
I think the most important thing is that you design your bow around the wood you are using. A full compass tillered 50#  boo/ipe bow 72" long would likely be too narrow to be stable or too heavy to be efficient, ut thta said a 50# hickory/ ipe elb broke some flight records last year, but it was only about 60" long. Design is everything, far more important than the wood species. Steve
I agree....... completely.

To get a true ELB with a 7/8 ratio it would be really narrow, perhaps too narrow.  The bow would be 3/4" to 7/8" wide. Scary narrow I think. If you don't mind making it with a flat belly it would be a lot better option. Also an Ipe core is counter productive. It adds too much weight to the bow and the core is not really a working portion of the limb.  Much better to have the hickory as the core and the Ipe as the belly.  Justin
Everything happens for a reason, sometimes the reason is you made a bad decision.


SW Utah

Offline Coo-wah-chobee

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Re: Difference between Bow woods for performance?
« Reply #7 on: November 14, 2008, 08:51:49 pm »
.......Just use Ipe thats it. All wood will make a bow, depends on what you are going ta do with it ?..................bob

Offline Badger

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Re: Difference between Bow woods for performance?
« Reply #8 on: November 15, 2008, 04:01:16 am »
    I use my mass formula on elbs all the time. It tells me how to tiller them basec on the wood density. If I were to build a hickory backed ipe bow 72" long and only 50#, the mass formula would give me about 15 oz total weight for this bow, assuming a full compass tiller. if I were to build it as narrow as possible and still keep it stable I would likley be no less than 22oz or 23oz. By changing the tiller shape and stiffening up the center a little bit and using a more elyptical tiller the mass allowance would go up to about 22 oz. Today i built a 55# 68" hickory backed osage elb. came in at 18 oz, which is just right for a slightly stiffer midsection. The way you know if it is working or not is to check the cast on the bow either by flight shooting it or shooting through a chrono. If you can shoot a 10 grain per # arrow 190 yards or better your design is good. Steve

Offline Ryano

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Re: Difference between Bow woods for performance?
« Reply #9 on: November 15, 2008, 11:00:47 am »
Definitely use the ipe as the belly not hickory. Hickory is crapy as a belly wood but would make a great backing strip if the grain is right. It would probally make a better core wood than ipe being a bit lighter in physical weight.
Its November, I'm gone hunt'in.......
Osage is still better.....

vCo2v

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Re: Difference between Bow woods for performance?
« Reply #10 on: November 15, 2008, 06:43:53 pm »
so then would there be any difference in adding hickory at all?

wouldn't it be better just to do bamboo/ipe than bamboo/hickory/ipe? or is there some property that hickory has that would make it a good core?