Hello John,
The DX Engineering Mast Load Estimator was my idea. It certainly takes the
guess work out of designing antenna loads on a mast. It is easy to use and
it's free.
http://www.dxengineering.com/mastloadestimator
Thousands of evaluations have already been run and it's only been on the
website for a month!
The calculations and results have been fully vetted through many amateur
radio antenna installers and also through professional mechanical engineers.
The results are accurate for the variables that are part of the evaluation.
We beta tested the estimator with a focus group and many of their
suggestions were incorporated.
No safety factor is applied to the estimator result. This was done on
purpose so people would not overload the mast with antenna wind loads and
then count on a safety factor to cover the overload. And yes, it only works
accurately for the DX Engineering masts that are in stock.
I hope this answers your questions.
73!
Tim K3LR
DX Engineering
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
john@kk9a.com
Sent: Thursday, February 06, 2014 7:49 AM
To: towertalk@contesting.com
Cc: k9zo@hotmail.com
Subject: Re: [TowerTalk] Mast pipe load calculator
I am not sure what the safety factor is of the program. It is a nice tool
if you are using their 4130 masts. There is no option to change the
material or wall thickness if using your own tubing.
Your proposed layout seemed reasonable, can the rest of your system
withstand 100 MPH winds?
John KK9A
To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: [TowerTalk] Mast pipe load calculator
From: Ralph Bellas <k9zo@hotmail.com>
Date: Wed, 5 Feb 2014 21:00:52 -0600
I found a really good mast pipe load calculator on the DX Engineering web
site.
www.dxengineering.com
They advertise a 22 ft X 2 inch pipe (also stock a 3" one) which seems about
perfect for my next upgrade. I made up a situation based on antennas that I
have around just to see how it worked. I put the mast 18 ft above the TB3
bearing, and 4 ft below so the rotor could be down a bit from the top.
Then I
placed a 205CA (9 sq ft) half a foot above the bearing. Then I placed a
155CA
(5.2 sq ft) 6 feet above the bearing. Then I put a 105CA (3.9 sq ft) 12ft
above the bearing. Finally I put a 6M7JHV (2.5 sq ft) at the very top
just to
see what would happen. For me, these are pretty realistic antennas.
The program has a good diagram and lets you fill in the names of the
antennas
and spacing so you can actually visualize your plan. Then you hit
"Calculate"
and get the result. In my example, the configuration passed 60 mph, and 80
mph, but failed at 100 mph. This is a great starting point! So I have to
downsize a bit. We get fierce winds and the antennas get covered in ice a
couple times in the winter. I really don't like stacking so many antennas
because it's nearly impossible to do any maintenance without taking
everything
down. This is so much more scientific that getting a Rohn mast and welding
some water pipe inside to beef it up a bit. It's fun to play with, but it
took
me a while because I just had to browse throug all the towers and associated
hardware.
RalphK9ZO
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