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 ``` 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 might be 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 ever 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 bottom. 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@contesting.com >> http://lists.contesting.com/mailman/listinfo/towertalk > _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```