In a message dated 97-02-07 11:45:41 EST, k2wk@crystal.palace.net (Walt
Kornienko) writes:
>Does anyone know how much the wind load is decreased
>by running coax against a tower leg. Hypothetically,
>A 1" wide by 144" long piece of SQUARE coax would have
>have a wind load of 1 sq ft. How much is the wind load
>decreased by being round.
>
Hi, Walt --
Good question. Most informed sources I've seen use a figure of
approximately 0.67 for round members. So your one square foot of calculated
area would be 0.67 square feet of round windload on the tower.
If you look at the Rohn catalog, the spec for 45G includes one 1/2 inch
and one 7/8 inch cable on each FACE. These six cables represent another
significant windload on the tower. Just running some quick calculations,
one of the 7/8 runs on a 100 foot tower is almost 5 square feet and the 1/2
inch is 2.8 square feet. The total cable windload on this tower is 23.1
square feet. By running the cables up a tower leg, the cable windload is
reduced significantly. I'll leave that more esoteric calculation for someone
else.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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