[TowerTalk] 30 foot Rohn 25G calculations

[bcarling at cfl.rr.com]

Thanks very much, Don,

We are still looking into this and I can go either way. I would actually prefer to go unguyed, 
but then I would need a large concrete base. About a 4 foot cube, Right?

Will that free standing aluminum tower guarantee to withstand 110 mph sustained winds and 
a 3 second gust of 139 mph? 
I kind of doubt it. Maybe I am wrong.

That is the requirement for my county in Central Florida.

Has anyone already done the TI222 calculations for that configuration?
I wlil have about 5.5 sq ft wind load with an A3WS beam and a Cushcraft 50-3 beam.

AF4K, Bry Carling

On 12 Feb 2015 at 14:00, n8de at thepoint.net wrote:

> Unless he is intending to put up a stack of huge monobanders and/or  
> SteppIR yagis, he doesn't need the 30" sections.
> 
> A free-standing Universal aluminum tower composed of 26" tapered, 22"  
> tapered, and 18" topper will support ANY common tribander/vertical/VHF  
> combo presently being used in ham radio.
> 
> Do the research ... I have 3 Universal towers up now ... and plan to  
> put up 4 more soon.
> 
> 73
> Don
> N8DE
> 
> 
> Quoting Gedas <w8bya at mchsi.com>:
> 
> > Brian, I would not rule out a free standing tower esp since you need to
> > stay under 30'.
> >
> > I have several self-supporting Universal towers here, each of which
> > uses as their first 3 sections, their 30" HD series sections.  When
> > assembling the towers and after getting those first 3 sections up in
> > the air, you realize how strong that structure is.
> >
> > In your case, since you mentioned 24', I would use two 30" HD sections.
> >  See if you can get the top section modified either by Universal or by
> > a local welding/fab place to make it a topper with a collar where you
> > can then use a 2" or 2.5" mast.  My gut tells me that two 30" HD
> > sections with a 4'-5' mast will still be standing long after your home
> > is leveled from some severe wind storm.
> >
> > Gedas, W8BYA
> >
> > Gallery at http://w8bya.com
> > Light travels faster than sound....
> > This is why some people appear bright until you hear them speak.
> >
> > On 2/12/2015 1:03 PM, Brian Carling wrote:
> >> Many thanks Bud.
> >>
> >> I will need to review which version they are using. Yes I had   
> >> someone pointing me in the direction of a freestanding tower but I   
> >> think I may go to using guys.
> >>
> >> It's either that or trade my tower sections in on a stronger better  
> >>  built freestanding tower designed for that purpose. I only need   
> >> about 24 to 28 feet in height. Maximum.
> >>
> >> Best regards - Brian Carling
> >> AF4K Crystals Co.
> >> 117 Sterling Pine St.
> >> Sanford, FL 32773
> >>
> >> Tel: +USA 321-262-5471
> >>
> >>
> >>
> >>
> >>> On Feb 12, 2015, at 12:27 PM, W2RU - Bud Hippisley   
> >>> <W2RU at frontiernet.net> wrote:
> >>>
> >>>
> >>>> On Feb 12, 2015, at 9:58 10AM, bcarling at cfl.rr.com wrote:
> >>>> I am putting together a permit application with my city which   
> >>>> requires certfication for 139 mph
> >>>> for three second gusts as in TI-222 spec. Also steady 100 or 110   
> >>>> mph I think.
> >>>> We are making a 30 foot Rohn 25G tower according to the Rohn   
> >>>> specification with  4 foot
> >>>> cube base of concrete with no guys.
> >>> I?m not sure I understand what you?re hoping to find.
> >>>
> >>> My 4-year old Rohn catalog makes it VERY clear that 30 feet of   
> >>> Rohn 25 can hold only 1.7 sq. ft. of added antenna when the   
> >>> environment is 90 mph (ANSI/EIA-222 Rev. E) and NO ICE.  (For   
> >>> areas that experience icing, Rohn 25 is specified by the   
> >>> manufacturer at ZERO sq. ft. of additional antenna load!)  From   
> >>> your e-mail address and the wind speeds you mention, I?m going to   
> >>> guess you?re in Central Florida, and I daresay a 90-mph Rohn   
> >>> EIA-222 Rev. E specification is not going to be adequate for your   
> >>> city.
> >>>
> >>> Nowhere in your posting do you mention what total antenna,   
> >>> rotator, feedline, etc. wind surface area or wind load you   
> >>> anticipate putting on this tower.  But my guess is that NO   
> >>> freestanding 30? Rohn 25 tower is going to make the grade.
> >>>
> >>> Also, you fail to mention which version of TIA/EIA-222 your city   
> >>> is using.  The latest I?m aware of is Rev. G ? a substantial   
> >>> revision from previous methods of specifying wind loading.
> >>>
> >>> Bud, W2RU
> >>>
> >>>
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