Doug,
Without doing a full analysis, I don't know what the dead-weight lifting
capacity of a TX-455 is. The answer can't be gleaned from the .pdf file you
referenced earlier.
While you're not interested in lateral failure, having a leg buckle and
tower foldover is a likely outcome if the lifted weight is too high
(assuming the lift cable doesn't fail first). A column or cylinder is very
strong when loaded perfectly vertically. If there's any sideways component
of force, such as a breeze, a slight misalignment of the tower section, or
the load is off-center, the tower begins to bend and then bends some more
as gravity adds more bending moment. This is called the P-delta effect or
"moment magnification." This is the wobbly tower effect that Rick N6RK
reported earlier in the thread. Moment magnification is accounted for in
the TIA-222 equations.
You might want to call UST to see if they can offer any guidance. 73 Jim
K6OK
=================
KR2Q wrote:
Thanks Jim,Interesting take on the 200 pounds of antenna weight. I'm not
concerned about knocking the tower down laterally, I'm just interested in
the dead weight lifting capacity.You say that if the antenna weight is
reduced the SF capacity increases. Allow me to pose the question the other
way around. What if the SF of the antenna approaches zero (or what if the
lateral wind is zero mph)...then what is the allowable antenna weight?
That's the key for me. Thanks so much!
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