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pirate tech rules at WTT

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Re: pirate tech rules at WTT

Postby BK in TEXAS » Mon Apr 27, 2009 5:34 pm

Hornseeker wrote:I am just not convinced that core stiffness matters...I guess I can try some hickory or walnut or paduk that is nice and stiff and Very similar in weight to the foam...which is VERY limber... and see... OK..I"ll do that. I'll try and keep all else equal....

E


I know for a fact I could never come close to "keeping all else equal", but...you've made enough bows that you could probably pull it off, especially using the same riser. I'd be interested in the results. I'm not convinced (yet) either that core material makes much difference. But then again, all else being equal...maybe it does? I know I'm trying some NICE hickory in my next one :)
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Re: pirate tech rules at WTT

Postby Longbow » Mon Apr 27, 2009 7:36 pm

I hope Dan "pops up" on the board also. I had a chance to speak with him and could tell he's a quite and humble man. He admitted that he feels uncomfortable 'chatting' online. The information he shared about his bow left the impression that he thinks outside of the box ;).....at least the very small one I'm familiar with :o Nice job Dan!
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Re: pirate tech rules at WTT

Postby GraemeK » Mon Apr 27, 2009 8:46 pm

Hi Ernie

I think the story with core stiffness is that if you are only considering the bending and storing energy aspect of a limb then the stiffness is not an issue -- the catch is that to recover the energy you have to avoid the limb wanting to torque and twist or oscillate on release which it is inclined to want to do because there are always odd forces acting on the system during release --- because the stiff core resists these forces better than a floppy core you tend to get better energy recovery.

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Re: pirate tech rules at WTT

Postby Bill Howland » Tue Apr 28, 2009 7:46 am

GraemeK wrote:because the stiff core resists these forces better than a floppy core you tend to get better energy recovery.


Exactly! Well said. :)
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Re: pirate tech rules at WTT

Postby BK in TEXAS » Tue Apr 28, 2009 7:56 am

Bill Howland wrote:
GraemeK wrote:because the stiff core resists these forces better than a floppy core you tend to get better energy recovery.


Exactly! Well said. :)


See now that's interesting. In my head I thought stiffer cores would just increase draw weight, but what Grammy said makes sense to me.
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Re: pirate tech rules at WTT

Postby grizz » Tue Apr 28, 2009 8:17 am

Keep talking Greame, I'm still learning! :P
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Re: pirate tech rules at WTT

Postby jwillis » Tue Apr 28, 2009 8:18 am

Power (from stiffness) to weight ratio must be important. It is a physical fact. That's why carbon is usually faster. My glass bow and my single carbon bow were almost identical, but the carbon backed bow was much lighter. I didn't weigh it to see how much, but you could feel the difference just in your hands. It also shot 5 fps faster. Another related concept is this... in bicycle racing, we talk about "rotating mass" being the most important. That is the weight of your spokes, rims and tires. It is anything that is spinning. It is also the weight of your cranks, pedals, cleats and shoes. Even your socks and the amount of sweat they absorb affects your rotating mass and ultimately your efficiency. The farther the weight occures from the center of rotation, the bigger a difference it makes. For example, it is more important for the tires to be light than the center hub because they are moving farther. Bows are the same way...the mid-outer limbs and limb tips are the "rotating mass" even if it is better to simply call them "moving mass." Whatever you can do to lighten the moving parts and keep them the same strength, the faster they will go. Dan's bow is a great example with it's lightweight foam cores. I believe that stiffer and lighter cores are faster because of this physical fact. Jim
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Re: pirate tech rules at WTT

Postby Hornseeker » Wed Apr 29, 2009 10:06 am

"Dan's bow is a great example with it's lightweight foam cores. I believe that stiffer and lighter cores are faster because of this physical fact."

The only prob there Jim...is that the foam, unless its markedly different than mine, is not stiff at all..it is completely unstiff! Much like micarta if you've ever dealt with a piece of that that is about .1 and 30 inches long... It also wasn't any lighter than Aboo, but the aboo was much much mcuh stiffer....

When I get a chance, I'll do some weight testing and stiffness testing...

I have abunch of carbon that is identical..I can glue up limbs with the same thickness of ABOO, Foam, or hickory....shape them up and plop them on the same riser... should be interesting.

From what Graeme said...I am thinking my next bow is going to be double carbon with double foam cores, like the WTT set of limbs...but I'm going to plop an 010 - 015 strip of carbon in the core.... that could be interesting.. it will "stiffen" the core both laterally and longitudinally... and its so thin it wont do much for mass....

E
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Re: pirate tech rules at WTT

Postby jwillis » Wed Apr 29, 2009 10:23 am

Well...maybe I'm wrong. It will be interesting to see what your double foam core test shows! Jim
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Re: pirate tech rules at WTT

Postby Hornseeker » Wed Apr 29, 2009 10:34 am

Dont hold your breath...I have a Lot to do and dont even have the foam for it right now...
E
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