[TowerTalk] miscalculation

[Jim Jarvis]

Jim Lux correctly pointed out that I neglected to consider
that Bob's 55G was being lifted from a point 90' up the
tower...which multiplied the winch force by a 90' lever arm.
Thus, the 154,000 ft-lbs of rotational lifting moment I 
calculated was REDUCED by the 90' lever.  Brings it down to
something like 1711.11 lbs of load on the winch.

HOWEVER...things get gnarly when the tower is purely horizontal,
as the lever arm isn't helping...and the lifting angle is varying.
The force has to be factored by the sin of the angle.  

The other thing I can't see is how you'd get a fair lead on the
lifting guy, when the tower went horizontal.  Once you get below
the roof line, things get more complex....although if you could rig
a fairlead guide on the peak, it would act as a derrick, until the
tower came up to that level, and the cable lifted off the roof.

So much for mechanics at 5 am.  I'll try to resist the urge until
after coffee, next time.  

You could probably provide internal, lateral braces for the winch
area, but I still don't like using the house as a deadman.  

n2ea
jimjarvis at ieee.org