[TowerTalk] Roof top towers

[VR2BrettGraham]

While I've known K7LXC for over 20 years now (prior to _his_ first tower) &
would rarely disagree with him on something, I do on the use of thrust
bearings in roof towers.

I dunno if the GM products are anything like the JA-land erector set aluminum
things like the one I use, but if they are, here is a situation where use of
a bearing is of benefit.

There is substantial give to twist with these towers.  At a previous QTH I
had a KT-34 atop a 6m tall model, with a short mast & rotor near the top.
It didn't take much wind to frighten me as I slept right below it & could
hear it creak, groan & make other unsavory noises as it twisted away.

While I now have a quad with significantly less boom on the same tower, I
wouldn't dream of putting the KT-34 back on it if I hadn't used a mast that
put the rotor all the way near the bottom & a thrust bearing half way up in
addition to the top.

Why?  Even now that the torque goes into the tower significantly lower than
before, I can feel that the tower is substantially "firmer" thanks to the
mast & its "attachment" to the tower through the bearings.  I'd even consider
adding another section to it now, if I could get the guy anchors out further.

Oh yes, these things are perfectly climbable.  My weight (~75 kg) is enough
to bend the horizontal braces, so one must be careful if you're not a runt
like me.  I've spent hours on top of the thing mucking with antennas & have
even been up it during typhoon conditions.  On this point I agree with me
mate Steve - the "don't climb" thing is total bollocks.

73, VR2BrettGraham



--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm