[TowerTalk] 10 inch tube 100ft wind load? NN7J

[Robert Chudek - KØRC]

Dan,

You can put your numbers through the WD9P mast calculator and see what you get, Here's the URL:  http://www.math.niu.edu/KARC/mast/

I put your numbers into the calculator, just out of my own curiosity...

SF = 2
WL = 0.004
MS = 60,000
OD = 10
ID = 9.732
TL = 100
HAS = 100
Ant1 = 1 + Area = 1
Ant2 = 0 + Area = 0
Ant3 = 0 + Area = 0

It told me this:

Survival velocity = 38.9 mph
Failure velocity = 55.1 mph
Mast Weight = 1,415.29 lbs

But if you used 1/2 inch wall, 10 inch diameter steel,

Survival velocity = 71.2 mph
Failure velocity = 100.6 mph
Mast Weight = 5,085.03 lbs

And if you used 1 inch wall, 10 inch diameter steel,

Survival velocity = 93.2 mph
Failure velocity = 131.9 mph
Mast Weight = 9,634.80 lbs


Of course if you are serious about installing something like this, a qualified design engineer should be your first step. The calculator can give you an idea of what kind of forces you are dealing with but as it warns, it is for instructional use only.

Note, these figures were with a 1 sq ft two-meter vertical at the top, not even a small yagi! You can plug in 8 to 20 sq feet of area for Antenna 1 and see what happens. The results surprised me (assuming the calculator is working correctly).

Free standing rotating tower systems like this have been engineered by HyGain (I think) and were called "Big Berthas". I knew of 3 installations in Minnesota, but nothing more. I'm sure other TT members can jump in with facts, figures, and stories about these types of installations.

73 de Bob - K0RC in MN


Message: 7
Date: Thu, 31 Aug 2006 06:34:26 -0700 (PDT)
From: Dan D <yaesu4u at yahoo.com>
Subject: [TowerTalk] 10 inch tube 100ft  wind load?  NN7J
To: towertalk at contesting.com
Message-ID: <20060831133426.27075.qmail at web58303.mail.re3.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

How do you calculate how much load  a steel tube 10 inch with .134 wall can handle with no guys 100 ft tall.
   
  Dan NN7J.