[Top] [All Lists]

Tower Ratings - Stupid Question

To: <>
Subject: Tower Ratings - Stupid Question
From: (Bill Coleman AA4LR)
Date: Thu, 19 Dec 96 15:07:47 -0500
>The tower is heavy duty model, rated @ 30 sf / 50 mph  (I know, I know,
>the wind blows harder than that!!!)

This raises an interesting question. If the lowest wind in the TIA 
standards is 70 mph, why do tower manufacturers specify tower capacity in 
terms of 50 mph wind? 

Since wind pressure increases with the square of the velocity, and 50 mph 
is roughly 1/sqrt(2) * 70 mph, this has the effect of presenting DOUBLE 
the capacity at 70 mph. (Other things being equal -- which they rarely 
are, since the tower face itself contributes considerable drag)

Also, for crank-up units, shouldn't there be different ratings for the 
extended and nested positions?

Sign me, Confused.

Bill Coleman, AA4LR           Mail:
Quote: "Not in a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

FAQ on WWW:     
Administrative requests:
Sponsored by Akorn Access, Inc & KM9P

<Prev in Thread] Current Thread [Next in Thread>