I think they state it that way because the average guy wouldn't understand
what you just said. ;<)
It is my understanding that the max force would be the force generated by a
70 mph wind blowing on a 15 sq foot surface. I guess at the top of the
tower. To be picky that would vary with altitude, humidity, and barometer
pressure. Since most antenna manufacturers quote a square foot wind load for
their antennas, this give a quick and dirty method of judging if your tower
can take a particular antenna.
> -----Original Message-----
> From: email@example.com [mailto:towertalk-
> firstname.lastname@example.org] On Behalf Of Charles Coldwell
> Sent: Thursday, February 18, 2010 11:16
> To: email@example.com
> Subject: [TowerTalk] wind load
> I've been looking at various tower specifications, and often see
> something like this
> Maximum Wind Load
> 70 MPH 15 sq. ft.
> I don't really understand how to interpret this. I think a wind load
> is a (static) force, and therefore should be measured in either
> newtons or pounds. IIUC, it should be proportional to the square of
> the wind speed and that the constant of proportionality should itself
> be proportional to the cross-sectional area to the wind. So 15 sq ft
> is an area, and 70 MPH is a wind speed, but I'm still missing some
> factors in order to calculate a force.
> Can anyone shed some light?
> 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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