On 06/06/19 19:18 PM, john@kk9a.com wrote:
I missed the torque part however I wish someone could explain this in simple
terms.
I'll give it a try.
Stick a tennis ball on top of a mast. It creates no rotational torque in
the wind.
Stick the tennis ball on the side of the mast, it creates torque in the
wind, like a wind vane.
Picture a balanced boom (balanced for wind...and weight if you like, but
I don't believe the weight is important for this).
Picture the boom going right thru the mast (ala Telrex elements that
went thru the boom).
A hypothetical symmetrical wind comes along. The boom does not rotate
because everything is balanced.
Now move the boom to one side of the mast. The wind will now attempt to
move the boom *downwind*, IOW, perpendicular to the wind on the downwind
side of the mast, because of the lever arm created by the distance
between the mast center and the boom center. Kinda like a weather vane.
Now add a second identical boom to the other side of the mast. Voila,
things are balanced again for wind force vectors.
I have to say though that it would seem that because of the small lever
arms involved, this concern is not worth putting much effort into. The
effect can easily be dwarfed by antennas that are not wind balanced.
-Steve K8LX
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