[TowerTalk] Fwd: guying distance

[N4ZR]

Hans, I wonder, did your analysis take into account the catenary curve 
caused by the weight of the guy wire? K1TTT did a nice, complete 
analysis of what's involved, somewhere on his web site.  I believe K7NV 
also has a lot to say about this on his web site, based on 
finite-element analysis.  From memory, the catenary curve is much more 
of a factor than EHS stretch - that's why tower manufacturers specify 
both a size and a static tension value for each guy, to take out much of 
the catenary.

FWIW, my 97-foot Rohn 25 tower had single guy anchors at 85 feet from 
the base, and guy sets at 31, 62 and 92 feet.

73, Pete N4ZR
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On 12/9/2018 11:30 AM, Hans Hammarquist via TowerTalk wrote:
>   
>   
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> Just to throw in my ten cents:
>
> I did a calculation once regarding how far out from the tower you should attach the guy wires. The calculation took into account the springiness of the wires (Yes, a guy wire stretch like a spring when you pull on it.) I found (I don't remember the exact value) that if you attached the guy wire ~130% from the tower you had the smallest movement on the tower due to the spring action of the wire.
>
> If you think about the extremes a guy wire attached 1) very close to the tower; a small stretch gives a large movement, 2) very, very far away from the tower: a small force gives a lot of stretch of all that wire.
>
> Also remember the closer the attachment point is to the tower the more down-force you will put on the tower.
>
> Further thoughts: I use four guy wires at 90 deg angle as that is less critical with the angle between the wires and a somewhat smaller tension on each wire (~10%). I have a square "strong-place" on/in the tower for the attachment of the four guy wires. That gives an easy attachment for the wires and is unloading any "pull-apart" forces on the tower.
>
> 73 de,
>
> Hans - N2JFS
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