[Top] [All Lists]

Re: [TowerTalk] wind load

To: "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] wind load
From: "Stan Stockton" <>
Reply-to: Stan Stockton <>, "Tower and HF antenna construction topics." <>
Date: Thu, 18 Feb 2010 14:20:59 -0600
List-post: <">>
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.

73...Stan, K5GO

----- Original Message ----- 
From: "Charles Coldwell" <>
To: "Tower Talk" <>
Sent: Thursday, February 18, 2010 1:37 PM
Subject: Re: [TowerTalk] wind load

> On Thu, Feb 18, 2010 at 1:34 PM, Stan Stockton <> wrote:
>> I could be wrong about this but have always thought (from an old Rohn 
>> book)
>> 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
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list


TowerTalk mailing list

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