Rohn 25 Fold Over Calculation

[Natan Huffman]

Ladies and Gents.....

I have one of those damn Rohn 25 foldover towers and am trying
to figure out how to compute the stresses on the top section and 
hinge.  Any of you engineering types know how to do it?

Here is my situation

I need to figure the amount of force generated by a specific tower
configuration.   The tower is a hinged tower (Rohn 25 Foldover)
that has a hinge 35' above the base.  Another 35' extends beyond the hinge
upwards.  Additionally,
the tower has a mast in it that protrudes 15'.  In the past I have put up
arrays and masts that weigh
100 lb.. with the top antenna weighing 35 lb. and placed at the very top of
the 15' mast.

What I need to figure out is what decrease in force on the hinge and top
sections can I 
see by moving the antenna down to the bottom of the mast (at the 72'
level.)

If the reduction is significant, I can put up another antenna!   Any ideas?

If I can do it,  I want to put the FORCE 12 EF180A (30 lb.) about 5' above
the
2 el 40.  Had the 40 (38 LB) at the top and would like to move it down to
the
thrust bearing and put up the 80 meter rotatable if the forces are less
than 
what I saw with the 40 at the very top.

You know how to calculate such things?

Natan

W6XR/2
Natan

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