[TowerTalk] Calculating Forces for Tilting tower

[Dave Hachadorian]

Maximum force in the rope is 743 pounds.

This is a "sum of the moments" problem.

The tower won't start to move until the rotating force in foot-pounds about 
the hinge in the upward direction exceeds the foot-pounds in the downward 
direction

Foot-pounds in the downward direction = (50#)(40') + (160#)(20') = 5200 
ft-lbs.
where:
50# is the weight of the load 40' from the hinge
160# is the weight of 4 sections of Rohn 25 with CG at a distance of 20' 
from the hinge

If you attach a line to the tower at 10' out and to the house at 10' up, the 
closest approach of that rope to the hinge is 7'.  That is the distance you 
use to figure the leverage of the rope.

Force in the rope = 5200 ft-lbs / 7' = 743 pounds
where
5200 is the downward moment
7' is the leverage distance of the rope.

Dave Hachadorian, K6LL
Yuma, AZ


-----Original Message----- 
From: Dave Tipton
Sent: Wednesday, May 29, 2019 6:37 AM
To: towertalk at contesting.com
Subject: [TowerTalk] Calculating Forces for Tilting tower

I have a 40 foot Rohn 25, with a tilt base section.   It will be sitting 
next to a detached framed (not block) garage with siding.

I can attach a winch to an extra guy bracket I have at the ten foot level.

There will be roughly 50 lbs at the top of the tower.  (Rotator, Hex Beam, 
GP3)

How much is the maximum force required to raise this from a cable at the 10 
foot level?

Thanks,
Dave, W5DMT

Sent from my iPhone
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