Yes, of course the EHS guys are not stretching (noticeably), but that's not
really the point (although it was the original question).
It seems to me that the physical extent of the catenary is pretty much
irrelevant for what we are discussing here (a person on the tower wiggling
around). It seems that it's the tension in the guys that counts. In other
words, the tower doesn't know (or care) whether the "droop" is two inches or
two meters; what it does know is that some force is pulling on it at some angle.
Of course, as the tower moves from its "steady state" (sorry--I'm an
electronics man, not an ME) condition, the increase in tension will occur less
rapidly if there is a pronounced catenary rather than none at all.
In your latest post you say that the movement is a few inches, whereas in the
earlier one you say it "will take your breath away."
Now, I'm not trying to be argumentative here; I'm just trying to get at the
facts--how much does a typical properly installed guyed tower really sway . . .
and how much does a typical properly installed free-standing tower really
sway? Does a guyed tower really sway all that much more than a free-standing
one?
Several years ago, I was talking with a man who makes his living trimming
trees. At that time, he was taking a break from working in some 120-foot
trees. He said that he recently had been asked to replace a lamp at the top of
a (guyed) radio tower. He allowed as how he felt _really_ uncomfortable on
that tower as it swayed, but the movement of the trees didn't bother him. So,
yes, I do believe that the things actually move!
Comments from professional tower people?
Thanks.
Jim, W3WV
> No, EHS guys are not stretching to give this effect.
>
> The guys are not tightened to make them straight, they are tightened
> to present a certain designed tension on the tower.
>
> If you sight down them, you will see that they are not pulled
> "straight-line" taut. They have a certain "bow" to them. This is a
> function of the weight of the guy pulling down in the center against
> the design tension trying to pull it straight, and the gradual loss of
> leverage to lift the middle by pulling as the line becomes straighter.
> The higher the tension, the less the bow, the smaller the tension, the
> more the bow.
>
> The higher the guy point the more obvious the droop because of the
> length of the guy, both adding to the weight and to the opportunity
> for droop.
>
> Pushing on the tower away from the guy adds tension to the guy, and
> lessens the "droop". AND the tower moves away from the guy point by
> the amount given up by the lessening of the droop.
>
> This will give you the inches drift in the wind that seems like feet
> when amplified by the tower top pucker factor.
>
> 73, Guy.
>
> ----- Original Message -----
> From: <W2fca@cs.com>
> To: <towertalk@contesting.com>
> Sent: Friday, April 18, 2003 8:21 PM
> Subject: Re: [TowerTalk] Guyed self-supporters (was "Concrete
> suggestions")
>
>
> > In a message dated 4/18/03 13:12:19 Eastern Daylight Time,
> > olinger@bellsouth.net writes:
> > << I have been at the top of guyed towers, and my own self-supporter
> in high
> > winds, and the movement in the wind at 100' on a guyed tower will
> take your
> > breath away. I never have felt that at the top of the Trylon. It
> simply does
> > not move like a guyed tower. >>
> >
> > Does that mean that on a 100 foot tower guyed with 3/16 EHS at the
> > recommended tension that those guy wires will be stretching on the
> order of
> > several inches or more?
> >
> > Frank
> > W2FCA
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers",
> "Wireless Weather Stations", and lot's more. Call Toll Free,
> 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather
> Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
> and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
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