Efficiencies

soccerkid812
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Re: Efficiencies

Post by soccerkid812 » May 3rd, 2011, 2:51 pm

googlyfrog wrote:This may be a really stupid question, but what's warping?
http://en.wikipedia.org/wiki/Wood_warping

basically wood bending

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Re: Efficiencies

Post by jander14indoor » May 3rd, 2011, 2:53 pm

Don't believe in stupid questions, just something you haven't learned yet. So:

Warping. Wood shrinks as it dries and shrinks different amounts depending on which direction through the trunk you go. It shrinks much more along a circumference, than along a radius. As a result, a flat/straight cut piece of wood can twist and distort as it either dries from cutting, or as it absorbs/desorbs moisture from the air as humidity changes (dry, heated air in winter, humid hot air in summer if no AC). Which way it distorts depends on where you cut the wood from the trunk, which way the tree was leaning, which way the sun was, even which way the wind blew most of the time. This twisting/distorting is called warping.

So, why lay it flat? IF the warping forces are small enough, and if you lay the wood on a flat surface in a nice stack, gravity restrains the twisting forces so the wood stays flat and the forces become internalized. It may still warp when you unstack or cut the wood, but less likely. Standing on end, there's nothing to restrain this twisting and the wood can take amazing shapes.

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Re: Efficiencies

Post by jander14indoor » May 3rd, 2011, 2:54 pm

err, umm, yeah, what soccerkid812 said.

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googlyfrog
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Re: Efficiencies

Post by googlyfrog » May 3rd, 2011, 3:35 pm

jander14indoor wrote:Don't believe in stupid questions, just something you haven't learned yet. So:

Warping. Wood shrinks as it dries and shrinks different amounts depending on which direction through the trunk you go. It shrinks much more along a circumference, than along a radius. As a result, a flat/straight cut piece of wood can twist and distort as it either dries from cutting, or as it absorbs/desorbs moisture from the air as humidity changes (dry, heated air in winter, humid hot air in summer if no AC). Which way it distorts depends on where you cut the wood from the trunk, which way the tree was leaning, which way the sun was, even which way the wind blew most of the time. This twisting/distorting is called warping.

So, why lay it flat? IF the warping forces are small enough, and if you lay the wood on a flat surface in a nice stack, gravity restrains the twisting forces so the wood stays flat and the forces become internalized. It may still warp when you unstack or cut the wood, but less likely. Standing on end, there's nothing to restrain this twisting and the wood can take amazing shapes.

Jeff Anderson
Livonia, MI
Would putting more rubber bands around the stack, or heavy weight on top of the stack also decrease the chance of warping? Also, is thicker or thinner wood more likely to warp? Thanks.

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Re: Efficiencies

Post by TYG » May 3rd, 2011, 4:18 pm

Thinner wood is more susceptible to warping-- http://www.kiae.org/wdc/KIAE_KWDC_Build ... 110118.pdf

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Re: Efficiencies

Post by TYG » May 3rd, 2011, 4:18 pm

TYG wrote:Thinner wood is more susceptible to warping-- http://www.kiae.org/wdc/KIAE_KWDC_Build ... 110118.pdf
The link also answers the weight question, and states the ideal conditions for storage

EDIT: sorry, meant to edit, not quote :|

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Re: Efficiencies

Post by drifter601 » May 3rd, 2011, 6:30 pm

So, what the highest efficiencies you guys are getting or have seen???
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Re: Efficiencies

Post by googlyfrog » May 4th, 2011, 2:50 pm

The highest at our state was 32, but I have heard of towers in the mid to upper 40s.

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Re: Efficiencies

Post by jander14indoor » May 5th, 2011, 1:08 pm

Check back a couple of pages, reliable (ie tournament results) reports of 40+ results going to nationals.

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Re: Efficiencies

Post by havenguy » May 6th, 2011, 1:11 pm

What do you think an efficiency of 30-35 would get us at nats? Thanks.
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