[TowerTalk] Wind Surface Area

[Robert Chudek - K0RC]

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 at live.com>
Subject: Re: [TowerTalk] Wind Surface Area
To: <towertalk at contesting.com>
Message-ID: <BLU121-W2184923767DB3ABECC472BF1E40 at 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 at juno.com
> Date: Mon, 14 Sep 2009 13:50:15 -0400
> From: k2qmf at juno.com
> CC: towertalk at 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 at live.com>
Subject: Re: [TowerTalk] Wind Surface Area
To: <towertalk at contesting.com>
Message-ID: <BLU121-W2184923767DB3ABECC472BF1E40 at 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 at juno.com
> Date: Mon, 14 Sep 2009 13:50:15 -0400
> From: k2qmf at juno.com
> CC: towertalk at 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