Hi again, Tim;
I forgot to mention a temporary base I built for a self-supporting tower
several years ago. It consisted of 4 treated timbers standing in the
ground several feet apart, to achieve a favorable moment arm.
Additional timbers were bolted to them above ground to create a base
for the self-supporting crank-up. The weight of the steel crank-up
multiplied by the moment arm or 'radius' prevented it from moving. I
never left the tower up when not in use, which prevented storm stress.
It worked fine, though it was not really engineered. It was located
away from anything it could have hurt if it had fallen over.
73 de WO?W
Tim Makins, EI8IC wrote:
>Many years ago, at school, I remember seeing the illustration of how you
>could move the world if you had a long enough lever. It occured to me
>recently that the same idea could be used to construct self-supporting tower
>bases, but, as I'm not an engineer, I thought I'd come to Towertalk to be
>proved wrong.
>
>The idea is: Instead of the usual cube of concrete, how about using a
>horizontal cross. Maybe 2 feet deep, and 2-3 feet wide, with an internal
>rebar cage to prevent snapping. The length of each arm of the cross to be
>determined by whatever formulas you guys use - I was thinking along the 12
>foot mark, as a discussion-opener.
>
>You will note that I haven't mentioned tower height, as obviously all the
>parameters inter-relate. If you must have a figure, lets say 40-60 feet.
>
>The reason for this ? Well, I was thinking 'outback', and 'developing world'
>here, where a mechanical digger isn't always available. Easier to dig slit
>trenches than a big pit. Less problems from cave-in too.
>
>Sit down, take one of these beers, and discuss.
>
>73s, Tim EI8IC
>www.qsl.net/ei8ic
>
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
>questions and ask for Sherman, W2FLA.
>
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