I am curious how many guys have first hand knowledge of an amateur radio
tower (properly guyed) coming down as a result of overloading and how
many instances there really are as compared to the number of towers that
are severely overloaded?
I had a tower buckle one time because a tree fell on the top set of guy
wires, but honestly have had seen a lot of towers WAY overloaded, beyond
what I would even do, and in 40 years cannot remember ever knowing
anyone who had a tower failure with ham antennas installed.
In most cases the tower specs include a huge amount of safety factor
along with specs that include multiple, large coax cables from top to
Everyone has a comfort level which needs to be satisfied.
----- Original Message -----
From: "Charles Coldwell" <firstname.lastname@example.org>
To: "Tower Talk" <email@example.com>
Sent: Thursday, February 18, 2010 1:37 PM
Subject: Re: [TowerTalk] wind load
> On Thu, Feb 18, 2010 at 1:34 PM, Stan Stockton <firstname.lastname@example.org> wrote:
>> I could be wrong about this but have always thought (from an old Rohn
>> that 70 MPH equated to 30 pounds per SF of antenna.
> OK, so in my example if the maximum wind load at 70 MPH is 15 sq ft,
> and we have 30 pounds per square foot, that works out to 450 pounds of
> force. That sounds reasonable.
> If we believe the force grows as the wind speed squared, and that a 70
> MPH wind puts 30 pounds per square foot of force on the tower (and
> that a 0 MPH wind puts 0 pounds), then the constant of proportionality
> is 30/4900. So that means the general formula would be
> F = 3/490 * W * W * A
> where F is the force in pounds, W is the wind speed in MPH, and A is
> the antenna effective cross-sectional area in square feet.
> What's the title/author of the Rohn book?
> Charles M. Coldwell, W1CMC
> "Turn on, log in, tune out"
> Winchester, Massachusetts, New England (FN42kk)
> GPG ID: 852E052F
> GPG FPR: 77E5 2B51 4907 F08A 7E92 DE80 AFA9 9A8F 852E 052F
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