Actually a 40ft R25 tower bracketed at 8' would probably
handle 130 MPH with no antennas installed. When I ran
the calcs for my 34ft R25 tower bracketed at 8', it came
out to 150 MPH wind survival (6700 ft-lbs overturning
moment at house bracket) with no antennas installed.
With an Cushcraft A3 tribander on top, it derated down
to ~85 MPH. Nevertheless, if James wants to maintain the
130 MPH rating and actually put an antenna on the tower,
he's either going to need guy wires or a stronger tower.
If I may take this thread a little afield ...
Does this not also suggest that a 55 foot Rohn 25 tower
with a tilt base tied to a pair of 25 foot sections on either
side and "guyed" only from to the back leg of the triangle to
a "dead man" (perhaps two of them) with a winch for the
purpose of raising and lowering might also handle a
similar load (insurance nannys disregarded)?
I have the sections, would just need to rig the winch.
The lowered tower would rest on a steel shipping container.
Any difference in strength between the same setup
tilted at the very base or at 5-10 feet up?
Thanks! & 73, doc kd4e
A blessed and joy-filled New Year to all!
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