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[Towertalk] Mast Length inside Tower

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Subject: [Towertalk] Mast Length inside Tower
From: (
Date: Mon, 2 Sep 2002 16:47:18 -0600
On Mon, 2 Sep 2002 "Julio Peralta" <> writes:
> Why do you say to put up to 10' of mast inside the tower. It seems to 
> me to be a waste of mast.
> Julio

A long mast above the top of a tower creates a BENDING MOMENT
in the upper section of the tower that is transmitted throughout the

I have seen installations with 18 feet of mast above the tower and 
only 2 ft inside the tower, creating a 9:1 lever arm working against
the top of the tower.  This worries me.  I 'feel' a lot more comfortable 
with at least 1/3 of the mast inside the tower.

On Rohn 25, it is difficult (but not impossible) to put a rotor in the
middle of a section.  It is easier to place the rotor on a plate at 
the top of the next section down (and cut one of the horizontal
braces at the bottom of the Top Section if necessary).  I agree,
this does 'waste' some of your heavy and expensive mast.

Tom  N4KG

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