[TowerTalk] 45G Wind Load

[Mark Robinson]

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 at aol.com>
To: <towertalk at contesting.com>; <aldermant at 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 at 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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