[TowerTalk] Assembled tower; lifting by Crane

[Tom Rauch]

> lift from a single point, without damaging the tower.  Or
said another way,
> how long of a Rohn 25 tower can you lift, assembled:
> 1.  from a mid point?

Not as much as around 2/3 up.

Think of it as a series of levers and fulrums. The largest
stress is at the first when you start to lift and it is all
nearly horizontal. When you grab at 2/3 (empty tower) you
have the upper 2/3 about balanced. The bottom of the bottom
1/3 is on the ground (With PVC pipe and caps over the open
legs)
so the pivot point of the crane and tower hanging at the top
counterweights the long section below reducing stress.

> 2. From one the top, with the base on the ground?

Well, I think the middle might sag a bit then. You can watch
it carefully as they lift and see.

I'm sure there is some limit to how much you can have on the
top at a given tower length.

73 Tom