TT:
>
> Mast failures are bent masts right at the top of the tower due to the
>bending moment of the mast and antenna load. Tower top failures are
>relatively rare - the mast will typically bend before the tower does.
>
>Cheers,
>Steve K7LXC
>TOWER TECH
While this may be true for most guyed towers, I wouldn't expect a
self-supporter to fair as well under similar heavy lateral loads.
When I was planning my Trylon project, I used the company's software to
test various antenna loads on various Titan models. In most calculated
failures (according to the software), the tower would break somewhere at the
third or fourth section. That is, depending on placement of antenna loads
and wind speed, the net safety factor would fall to less than unity at
either 24 feet or 32 feet above ground. (This failure, by the way, occurred
at 90+ mph with the antenna configuration that I've described before.)
Using the same antenna configurations, I calculated that quarter-inch
wall CM tubing would withstand the loads (and then some). The mast in those
cases would NOT fail first.
BOTTOM LINE: Climb the mast on your guyed towers if you dare, but think
long and hard about such on self-supporters, especially on windy days.
Timberrrrrrrrr!
73 de
Gene Smar AD3F
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