[TowerTalk] RE adding up wind loads

[Kurt Andress]

There is information about how to take your tower rating (with all the antenna load at the tower top) and convert that to what most folks really do (stack antennas above the tower top) in the 19th edition of the ARRL Antenna Handbook (and later versions).
Take a look at that, and you will probably be able to figure it out.
Please read everything there about it! You will find that area figures provided by some of your favorite antenna Mfgr's, may not be right for doing the calculations presented.

73, Kurt, K7NV



Original Message  ------------------------------

Message: 4
Date: Wed, 31 Jan 2007 10:47:08 -0800
From: "Jeff Kinzli" <kinzli at kinzlicoils.com>
Subject: [TowerTalk] adding up wind loads
To: towertalk at contesting.com
Message-ID:
<e4a9cfd80701311047i28c22639n1564f700921b89cb at mail.gmail.com>
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So I know that wind load at the top of the tower is much different
than wind load 10 feet up from the top of the tower, and that towers
are wind load rated at the top of the tower.

I'm trying to understand how this fits together in terms of stacking
yagis. My plan is to use a 4el Steppir and a 2 el Cushcraft 40M about
10 feet above that. With the roughly 10sqft for the Steppir, and 6
sqft for the Cushcraft, that's 16 sqft total, but I'm sure it's quite
a bit more than that given the stack, and ratings for towers looking
at the wind load at the top of the tower rather than 10' above the
tower.

Are there calculations that I can do to figure out how much tower I
need to support this? Or would that be something a civil engineer
would do (or my architect) before I get the permit for the tower (and
buy the tower).

Thanks for any ideas...

-J


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