[TowerTalk] Tower windload with trees blocking

[Bill Coleman AA4LR]

On 4/13/99 10:27, km1h@juno.com at km1h@juno.com wrote:

>As a for instance I have 70-80' trees at my QTH. Just about anytime I
>climb the 180' tower I can start with almost dead calm at ground level
>all the way up to the treetops. About 20' above the trees the wind starts
>to become noticable and at 180' it is a definite factor. So much in fact
>that I have to add a few pounds of weight to a drop line.
>Once the line hits the treeline it goes straight down with the upper part
>in full sail effect.

Pilots notice this, too. I used to fly out of a small airport that was 
surrounded by 50-80 foot trees. Once you got down below the treeline, any 
crosswind correction you were holding had to change fast if you wanted to 
stay lined up with the runway. We also had to contend with the wind 
swirling around a large beolith (a rock mountain) about a mile and a half 
away.

Even at a very clear airport, the wind tends to intensify as you ascend, 
at least for altitudes up to around 500 AGL. (which is well above any 
practical amatuer tower height)



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


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