[TowerTalk] 4 guy wires OK?

[Lowell, Mark]

Sorry for the delay, this message keeps bouncing - Mark

>Please  do not try *this* at home!
>*this* =  guying THROUGH the tower.
>de  Tom  N4KG

Tom is right, guying through the center of the tower to a leg on the
opposite side creates an "un-stable structure", one that will not stay in
its initial position.
 Although it may be possible to balance the guys for a while, as soon as
the tower twists at all from the wind acting on an antenna, or a climber
twisting around, for instance, a torque will be created by the guy tension
pulling on the leg, because the guy now no longer runs exactly through the
geometric center of the three legs.

 Once this happens, the tower, which acts like a torsional spring, will
stay twisted in one direction to varying degrees, as the torsional load
balances the guy tension, assuming that the base cannot rotate. This is
fine for resisting torque from the wind in the opposite direction, but
when the wind-induced torsion adds in the same direction, you're creating
a total torsion that the tower wasn't designed for. In addition, your guy
tension will be somewhat reduced if the tower bends and takes a permanent
twist. I guess it could stay up, and apparently some do, but it is not an
ideal situation.

In this scenario, there would seen to be a great advantage to using
pier-pin base construction, rather than embedding the bottom section in
concrete: the entire tower can be rotated to accommodate a change in the
anchor positions. (then you'll have to find <gulp> 'true north' again and
re-align your rotor <grin>)
 If you can't rotate the tower, some sort of guy ring must be fabricated
so that the guys can be attached to the outside of the tower, such that
the guy, when projected, will pass through the geometric center of the
tower. I don't believe a standard Rohn guy attachment assembly is suitable
for such attachments between legs.

--...MARK_N1LO...--

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