Sorry Mat, but your interpretation is wrong and could lead to a tower failure.
Here's how that paragraph is presented:
"WIND LOAD is the worst-case wind resistance for the antenna. Using the latest
structural analysis, the wind load is either the total element wind load OR the
boom windload, whichever is the larger resistance to the wind. Most beams have
more element than boom wind load. The figure specified is the effective area,
which is the projected area of the elements or boom, multiplied by 2/3 for a
cylindrical surface."
Re-read the last sentence until it becomes clear that they have ALREADY reduced
the area by 2/3. So if their spec sheet says the antenna is 12 sq feet of wind
load, it's 12 sq feet, not 8 sq feet.
73 de Bob - KØRC in MN
------------------------------
Message: 4
Date: Mon, 14 Sep 2009 14:02:08 -0400
From: Mat Eshpeter <kk1c@live.com>
Subject: Re: [TowerTalk] Wind Surface Area
To: <towertalk@contesting.com>
Message-ID: <BLU121-W2184923767DB3ABECC472BF1E40@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Ted -- the Force 12 web site mentions that you can discount the wind load
calculation by a factor of 2/3 to account for the cylindrical surface of the
boom (unless the boom is in fact square). I discovered this fact here:
http://www.force12inc.com/101101.html in the "windload" section.
ciao,
Mat
KK1C
> To: k2qmf@juno.com
> Date: Mon, 14 Sep 2009 13:50:15 -0400
> From: k2qmf@juno.com
> CC: towertalk@contesting.com
> Subject: Re: [TowerTalk] Wind Surface Area
>
> Hello All,
>
> Many Thanks for all the replies.
> I should have figured that one out
> on my own....
>
> 73,
> Ted K2QMF
>
>
------------------------------
Message: 4
Date: Mon, 14 Sep 2009 14:02:08 -0400
From: Mat Eshpeter <kk1c@live.com>
Subject: Re: [TowerTalk] Wind Surface Area
To: <towertalk@contesting.com>
Message-ID: <BLU121-W2184923767DB3ABECC472BF1E40@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Ted -- the Force 12 web site mentions that you can discount the wind load
calculation by a factor of 2/3 to account for the cylindrical surface of the
boom (unless the boom is in fact square). I discovered this fact here:
http://www.force12inc.com/101101.html in the "windload" section.
ciao,
Mat
KK1C
> To: k2qmf@juno.com
> Date: Mon, 14 Sep 2009 13:50:15 -0400
> From: k2qmf@juno.com
> CC: towertalk@contesting.com
> Subject: Re: [TowerTalk] Wind Surface Area
>
> Hello All,
>
> Many Thanks for all the replies.
> I should have figured that one out
> on my own....
>
> 73,
> Ted K2QMF
73 de Bob - KØRC in MN
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