[TowerTalk] 4 Way Guying

[John Langdon]

The main thing is the additional downward force from the tension on the
fourth wire, since I have been told that the primary failure mode of 25G is
due to downward force.  Since you are already at a less than normal angle,
the three wire method will already give you greater downward force than the
Rohn recommendations, and then the fourth wire adds to that!  I am no PE,
but I did pass statics many years ago, and I would want one to buy off on
this.  Also I seem to recall that rooftop mounting is much less able to bear
high downward forces than a pad on the ground, unless you have taken special
precautions to couple the load to the structure properly.

I was once involved in a repeater group that put up a non-standard tower
configuration that later damaged the roof of the building and the ownership
and their insurance company made use eat a lot of doo doo over that.  I t
was like Chinese water torture by threatened litigation.  I wished to hell I
had used a standard drawing or had a PE drawing then.

73 John N5CQ


-----Original Message-----
From: owner-towertalk@contesting.com
[mailto:owner-towertalk@contesting.com]On Behalf Of Richard Thorne
Sent: Wednesday, March 29, 2000 1:22 PM
To: Tower Talk (mail list)
Subject: [TowerTalk] 4 Way Guying


Hello Group:

I think this has been brought up before, but a search of the archives
was not much help.

I have my tower installed on top of my office building.  With 3 way
guying (spaced 120 degrees apart) I can get a distance of 50' between
the tower base and the guy anchor point.

I'd like to go higher to 90' so I'll have room for a 3 stack of C3's.
90' of tower calls for a guy anchor distance of 72'.  I can't get that
kind of distance with 3 way guying, but I can with 4 way guying.  ( A 3
guy system requires a space that is 120' square, with 4 way guying it
only requires a space that is 100' square, give or take a foot).  The
roof top is 100 deep by 200' long, so there just isn't room for a 3 guy
system.

Is there any reason I shouldn't do this?  I realize one of the tower
legs will have two guy wires tied to it, but it seems to me that 4 way
guying would provide a better structure.

--
73,

Richard Thorne
ARS N5ZC (ex KA2DSY, N2BHP, WB5M)
Remote Control Airplanes:  AMA# 657062
http://www.tcac.net/~rthorne/



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