I am trying to get wet sealed VA engineering drawings for Rohn 55G towers at
70' height, as this is a requirement for the building permit application in
Montgomery County, VA. I already obtained the required soil samples that shows
excellent ground for holding towers. I plan on putting up both a C31XR/HD and a
Magnum 240N/HD on each tower (combined weight of 170lbs), and using Yaesu 2800
rotors. Wind load will be about 20 sq. ft. Being on a mountain top, I want this
to be overengineered..But getting engineering drawings from Rohn has taken over
6 weeks and I still dont know if they will be able or willing to provide them.
Time is of the essence!
1. Any PEs out there who can do accurate engineered drawings for Rohn 55G with
guys and windloads, in case Rohn fails me? Rohn's standard catalog for 55G does
not go below 100' and I dont want to try and substitute 45G drawings that don't
meet windload. I am a PE myself, but would prefer a neutral 3rd party to do the
calculations.
2. Would a 2" steel mast pipe work, and what length/vendor/supplier would you
recommend? should I get a 15' mast pipe and have 5' in the tower and 10' above
the tower holding the 2 yagis? Is there a formula or rule of thumb for how much
mast pipe protrudes above the tower and how much goes into the tower for the
rotor?
3. I plan on using 2 sets of guy wires (should be enough, yes?), and wonder:
Should I attach the top set of guy wires to either (1) a tower top mounting
plate (with thrust bearing); (2) a guy mounting bracket a few feet below the
tower top; or (3) a torque arm stabilizer a few feet below the tower top? Which
one assures greatest stability in wind/ice on the mountain top? All of Rohn
standard drawins appear to show configuration(2).
Many thanks, Ted N9NB (trappaport@austin.rr.com)
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