[TowerTalk] Large Tower Base

[Patrick Greenlee]

Wilson, to recap...  The original installation was 100 ft tall with a large 
wind generator on top.  The three piers were 18 inches in diameter and 7 ft 
deep.  After spending a few minutes thinking about the situation and 
comparing the means at hand, I have decided to dig the pier holes with my 
backhoe-like ride on trencher rather than the 3PH mounted auger. I can get 
whatever diameter I want and greater depth this way.  An "L" shaped pier 
will resist pull-out better than a cylindrical one will.  I may exaggerate 
the horizontal component of the "L" to accentuate the pull-out resistance. 
Forming for a pour like this isn't very complicated. It is handy having a 
3PH mounted cement mixer for the tractor.  I may manually bell the "L" a 
little in the opposite direction of the horizontal projection at its bottom 
making for more of an inverted "T" configuration.  When it comes to pull-out 
resistance,  more is better if you don't go crazy.  I tend to over engineer 
things, erring on the side of extra strength.

I'll be getting to start this project real soon but first I have a 3 hr 
drive to a hamfest tomorrow (Saturday).  I will start clearing the brush and 
trees from around the tower base Monday.  Ib ll take my safety harness and 
climb the tower to apply penetrating oil to the fasteners.  I'm not sure if 
it will help much but it sure can't hurt. My mechanical engineer has 
requested wall thickness measurements of the roughly  4 1/2 inch diameter 
tubes so I'll take some digital calipers along.

Thanks for the kind words, Wilson.  Maybe a little over done, but 
appreciated.  Everything is relative. For folks with little or no hands on 
experience on the scale in question this project may seem "far out" and out 
of control. I recall back when knowledge of Rogallo wing hang gliders was 
uncommon and spectators used to say the darnedest things when they saw me 
preparing to run off a high cliff strapped to one.  Comparisons to Icarus 
were not uncommon.

Patrick AF5CK


-----Original Message----- 
From: Wilson Lamb
Sent: Wednesday, March 06, 2013 8:33 PM
To: towertalk
Subject: [TowerTalk] Large Tower Base

Lots of wasted bandwidth here!
Patrick is obviously one of the very few among us with knowhow and resources 
to get outside the box!
Until you work in a few fab yards and around a few drilling derricks, you 
donb t really understand possible!
With all his gear, raising this spindly little base will be a snap!
Ib d agree, however, that the proposed foundation piers sound a little small.
With all that gear, he should be able to just yank the old ones out by the 
flanges and reuse them.
We know nothing of his soil, but drilling about 8b  of 2-3b  hole and planting 
the old piers in them, surrounded by concrete, might just do it!
Positioning will be the hard part, so assembling the lower tower section and 
using it to locate the piers seems a good idea.
I think sitting up there with a cool one and watching the sunset over the 
Kansas plain will be a hoot...just be sure thereb s a handrail on that 
staircase!
Please get those pictures out asap, Patrick!
Wilson
W4BOH
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