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[TowerTalk] Beam in the Big Wind!

To: <towertalk@contesting.com>
Subject: [TowerTalk] Beam in the Big Wind!
From: force12@interserv.com (force12@interserv.com)
Date: Sat, 11 Oct 1997 11:30:14 -0700 (PDT)
Good morning.

Using a structural model has an advantage of being able to look at the 
element and boom wind loads, plus the wind load and mast torque in 10 degree 
increments. Most antennas have more element wind surface area than the boom. 
Some have multiple times the boom wind surface. The maximum wind surface 
area is usually between 25 and 50 degrees away from the boom center line.

The boom, of course, does not flex like the elements. Element flex will 
unload much of the force. The advantage of pointing the boom into the wind 
is that the elements are symmetrical to the boom. This makes the force 
equal (assuming the wind is the same on both halves of the elements) and 
theoretically no toqrue to the mast/rotator/tower. The typical boom has some 
offset to the mast, so it will impart torque on the mast/rotator/tower. This 
offset will make the antenna hunt into the wind. A fin can be effectively 
placed on the boom to equalize the wind load. Have used them for about 12 
years and they are amazing. I use clear polycarbonate sheet.



Have a good day and 73,
                        Tom, N6BT
                        Force 12 Antennas and Systems
                        (Home Page   http://www.QTH.com/force12 )



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