[TowerTalk] Wind pressure revision

[K7LXC@aol.com]

In a message dated 04/12/2000 6:51:11 PM Pacific Daylight Time, 
dickrts@texoma.net writes:

Hello, TowerTalkians --

      Dick Weber, K5IU, a PE who is intimately familiar with ham construction 
challenges sent me the following message after I posted a windspeed/wind 
pressure chart.

> Your chart is in error. Your chart  uses the old,  incorrect EIA222 formula 
> which includes a drag coefficient for a flat plate along with a factor for 
> gusts. 
>  
>  For wind pressure with no gusts and no imbedded drag coefficients you 
should 
> use the formula
>  P = .00256 V^2. This is the impact pressure of a steady wind stream with 
no 
> embedded drag coefficients. The later versions of EIA/TIA/ANSI 222 (rev D 
and 
> later) show this. You can also find this in ASCE7, and many engineering 
test 
> books going back 100 years. This whole wind loading thing got screwed up 
with 
> the earlier versions of EIA222 and gross misunderstandings within the ham 
> radio community. 

     Okay - I stand corrected. Here are the new figures:

70 MPH = 12.5 pounds
80 MPH = 16.4
90 MPH = 20.7
100 MPH = 25.6
110 MPH = 31

      Someone please confirm the figures. Bottom line? BIG winds are still 
BIG winds!

Cheers,    Steve   K7LXC
Tower Tech

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