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Re: [TowerTalk] Which Vertical is More Robust ?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Which Vertical is More Robust ?
From: jimlux <jimlux@earthlink.net>
Date: Wed, 1 Jan 2020 12:18:29 -0800
List-post: <mailto:towertalk@contesting.com>
On 1/1/20 11:35 AM, Richard (Rick) Karlquist wrote:
Extreme tapering has its limits.  At some point, the vertical
will not stand up straight even in the absence of wind.  The top will
always bend over at some azimuth.  Now if you take the top
portion only of this vertical off and ground mount it, you will find
that it will stand up straight.  I don't know this from theory,
or even software.  Rather: actually building it.  Who knew?

It's probably because it's not perfectly symmetrical, and as soon as it bends a little, will reach some sort of equilibrium. That asymmetry could be from, say, the sun shining on one side and the differential thermal expansion.

You could probably solve it as a differential equation for an idealized uniform tube - it would be similar to the deflection of a cantilever beam with a uniform load (where the load comes from differential expansion).





This would probably be a great interview question for an ME...



It would be an interesting question - especially to see if they have an analytical solution or immediately jump to an FEM approach.
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