My impression is that the 21.06sf is the wind loading of the tower itself.
On 08/09/12 07:02 pm, KR7X wrote:
> Where on the current Universal Tower web site did you find the 21sf at
> 110mph rating for the HD-21-50 rating? All they say there is if your antenna
> is xx SF go down the list that has the same number or larger than the
> antenna area I see no reference to wind velocity or what standard is used in
> their rating of tower capacity. Am I missing something?
> Lonberg Design Group, Ltd.
> H. S. Lonberg, P.E.,S.E.
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org] On Behalf Of email@example.com
> Sent: Thursday, August 09, 2012 10:55 AM
> To: firstname.lastname@example.org
> Subject: [TowerTalk] Aluminum Towers
> I plan to install a 50' tower and a tri-bander for 20/15/10 and was
> originally considering a U.S. Towers 55' crank-up model. While researching
> towers, I came across a company called Universal Towers that sells aluminum
> free-standing towers.
> Based on the specs, the Universal Towers HD-21-50 aluminum tower looks like
> it might be a better fit for the following reasons:
> * At $1989 it's $2K cheaper than the U.S. Tower crank-up
> * It only weighs 190 pounds (spread over five 10' sections), versus>800 for
> the crank-up, making it a lot easier to get off the truck with fewer people
> * The base doesn't require a rebar cage, making installation simpler
> * It won't rust
> The HD-21-50 is rated at 21 sq.ft. at 110 MPH, while the U.S. Tower crank-up
> is rated at 30 sq.ft. at 50 MPH.
> The installation instructions for the aluminum tower says to assemble the
> tower on the ground, attach the antenna(s), and then walk it up. In my case,
> I don't have 50' of horizontal space to do this. Is it feasible to climb
> this type of tower and assemble it vertically section-by-section with a gin
> pole? (Whatever I put up will be installed by a professional tower
> Any reason why I shouldn't consider this aluminum free-standing tower?
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