Now I understand why The Gravity Group, CCI, and other companies who build
wooden roller-coasters charge a much higher price when they use Douglas Fir. If
they spend the (lots of) extra money up front for Douglas Fir, I know they have
to replace sections of the wooden track much less frequently - I just didn't
know it was *that* much stronger!
>From: W7CE <firstname.lastname@example.org>
>Sent: May 9, 2007 8:50 AM
>Subject: Re: [TowerTalk] Tower in Tree
>> >Doug Fir is the strongest North American softwood
>> No kidding! I just looked it up on Matweb.com and the flexural yield
>> strength is listed at 8100psi!
>> The elastic modulus is about a thirtieth that of steel (1000ksi vs.
>> 30,000ksi) , but the cross section of the tree is huge compared to
>> Rohn 25G ...
>Exactly! The tree is much stronger and more flexible than a steel tower. I
>can't begin to estimate the wind load that the branches present, but it is
>probably measured in 100's of sq. ft.
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