[TowerTalk] RE: Tower Wind Calcs

[W7AOR]

Nevada P.E. wet stamp on docs for $250. Take it. That is cheap. No PE local
could do that.

Interesting that Henderson is asking for 90 mph. I thought that one could
just put up a tower in Henderson with the city being interested. Clark
County asks for 70 mph.

Beware that the original calcs for US Towers MA-40 is done at 50 MPH
Winds -- 16.5 sq feet; 85 lbs and at 70 MPH Winds -- 6.8 sq. feet; 65 lbs.
so at 90 mph what do you think happens to allowed antenna loading and
weight?

Good luck!
Kent W7AOR
www.narri.org

-----Original Message-----
From: Alan C. Zack [mailto:k7acz at cox.net]
Sent: Thursday, December 11, 2003 2:43 PM
To: TowerTalk at contesting.com
Cc: Antennas; Las Vegas Radio Club; reginfo at arrl.org
Subject: Tower Wind Calcs


I wonder if anyone would be kind enough to please point me in the
right direction to find the method of obtaining a Wind CALC
(calculation) for a tower project to satisfy my Building Department
I am ready to purchase a U.S. Tower's MA-40/MAF-40/MAB-40 combination
crank-up, fold over tubular tower.  I downloaded the Pier Footing
(base) installation drawing for this tower from the U.S. Tower's web
site and took it to my Henderson, NV, Building Department.  The
Building Dept approved my tower and said the drawing was fine, EXCEPT,
I needed a Nevada P.E. wet stamp on it (it has a CA PE stamp) and I
also need a 90 MPH Wind CALC.
First, I went to the ARRL web site looking for a ARRL volunteer P.E.
but there are none shown for the state of Nevada.  Next, I contacted
U.S. Towers and asked them for it.  I reasoned that since this is a
considerable sale for them they would provide the wind calc at a
nominal fee.  I was thinking this was something a computer generated
program could spit out in a minute or so, or that there was some sort
of table was available.  I was somewhat shocked when I was told the
charge would be $250.00.  When I asked why so high I was told no one
on their staff could do it and they had to sublet it out to an outside
P.E.  I am surprised that they have engineers who design and test
these towers but are unable to compute a 90 MPH wind calculation.  The
sales rep I spoke to was kind enough to email me the tower material,
bolts, etc stress analysis and other specs along with the same drawing
I had downloaded from the internet.  But the Building Dept still wants
the 90 MPH wind CALCS.
Is there someplace I can download the method of doing this.  I am
hoping I may be able to do the calculation myself and find a P.E. who
will recheck my figures and sign off on it for less than U.S. Towers
wants to charge me.  I have an EE (1965) and a IE (manf) (1989) and
think I would be able to do the numbers if shown how to do so.  I have
even considered testing for my own NV PE stamp which may be cheaper
than the $250.00 fee U.S. Tower wants but doubt if I could sign off my
own project.
I would appreciate any help someone would be able to provide.  If it
means finding a comparable tower from a different supplier who is more
buyer friendly I am open to that also.
TIA for any assistance.
--
__________________________________________________________________________
                                     Alan Zack
                     Amateur Radio Station K7ACZ
                         Las Vegas, Nevada, USA
          Quality Engineer, The Boeing Company, Retired
  Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
        U.S. Coast Guard, Always Ready, Always There
Every hour, Every day, Around the Clock and Around the World
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