I am in the same position as you and I am starting to think Rohn 55 as I
want to be able to handle 100mph.
Another option is to bolt 2 tower sections together but I haven't seen any
data for this approach
Mark N1UK
----- Original Message -----
From: <K7LXC@aol.com>
To: <towertalk@contesting.com>; <aldermant@windstream.net>
Sent: Saturday, 19 September, 2009 8:43 PM
Subject: Re: [TowerTalk] 45G Wind Load
>
> In a message dated 9/14/2009 10:04:05 A.M. Pacific Daylight Time,
> towertalk-request@contesting.com writes:
>
>> According to my Rohn manual, if I understand the drawings correct, the
> maximum wind load for a 70' 45G tower is 15.2 sq.ft. Can someone please
> confirm for me that this is correct?
>
> Yes, at 70 MPH. You should add in the 8.0 sq.ft. for a symmetrical
> mount at the top of the tower that's deducted per General Note #4 which
> will
> give you a realistic capacity of 23 sq.ft. @ 70 MPH.
>
>> The reason I'm concerned (this will be
> my first tower) is I see pictures of contest stations with five or six
> pretty big yagi's on Rohn 45G towers which I think must really be
> exceeding
> the wind load spec.? I am planning on (following the Rohn recommendations
> for tower installation) installing two OptiBeam yagi's, the 40m 2-el and
> the
> tribander 16-el, which have a combined wind load of 19.4 sq.ft.
>
> Amateurs are well known for overloading Rohn towers and Rohn towers are
> well known for tolerating these conditions.
>
>> I live in the south part of Georgia where the A58.1-1982 ANS shows my
> area
> between the 80 and 90 MPH wind speed zones.
>
> Go to _http://www.championradio.com/windspeed.php_
> (http://www.championradio.com/windspeed.php) for a better idea of your
> windspeed conditions.
> Contacting your local building department is also recommended.
>
>> Understanding (somewhat) the 'safety factor' included in engineering
> tower
> design, am I putting my tower/yagi system at great risk with a wind load
> that is 4.2 sq.ft. over recommended specs.?
>
>
>
> Follow the above steps and you'll more realistically see where
> you are.
>
> Cheers,
> Steve K7LXC
> TOWER TECH
> _______________________________________________
>
>
>
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