Wind area of mast.

[K7LXC@aol.com]

In a message dated 96-09-05 11:40:14 EDT, you write:
>I want to calculate the effective wind area of
>a 2" diameter mast that is 72" long.
>
>Therefore 72" X 2" = 144 sq.in = 1 sq.ft.
>
>The calculation above would be accurate if the
>mast were square.  But because it's round
>isn't there a constant I neet to multiply the
>result by.

Hi, Gene --

     You're just about there.  The round-member multiplier, or drag
coefficient, is 0.67.  It is used by Dave Leeson, W6QHS, in his book
"Physical Design of Yagi Antennas", page 7-6.

     The EIA/TIA-222-F uses a 'reduction factor' of .51e(squared) + .57
 where e is the solidity ratio.  They also have an appurtenance force
coefficient for a cylindrical appurtenance of 0.8 for an aspect ratio <7.
 You should investigate it further to look at the definitions and
applicability to your question.  This info is covered on pages 3-8

73,  Steve  K7LXC

     TOWER TECH -- professional tower supplies and services for amateurs