wind force design criteria

Dale Martin
Mon, 12 Aug 1996 22:24:37 -0500

Case in point: 

The club station at work had a 51' crank-up.  On it we had a 5 element,
10m beam, a TA-33 tribander (KN5H: help me if you are subscriber; I forgot!!),
and a Ringo Ranger. 

It was such a pain to crank it up and down, that operators finally left it up 
most of the time.  One night a big thunderstorm rolled through and the 
middle tower section failed, spiking the ringo into the ground and trashing
it and the other antennas.  

We salvaged the top and bottom sections, bought a replacement middle
section and left it nested and put Oscar antennas on it.  Then got a fixed
tower for the Oscar stuff and gently laid the crankup on 4"x4"'s next to the
building with the idea of offering it up at the next flea market (that was at least
10 flea markets ago.

I would recommend to anyone considering purchasing a crankup tower or 
any current owners of manually cranked towers to seriously consider 
buying an electric motor for the winch.  

All it takes is that one time you decide not to crank the tower down after the
band closes at 2:00am.


From: 	Stan Griffiths[]
Sent: 	Monday, August 12, 1996 7:25 AM
To: 	Henry Knoll
Subject: 	Re: wind force design criteria

>>If you think about it for a minute, any crankup that is fully extended and
>>with no antennas on it at all will come down at SOME wind speed. 
>Any tower will come down at SOME wind speed.
>Henry  WA0GOZ

Yes, but the POINT is (gee, do I REALLY have to state it?) that a free
standing, extended crankup will come down at a MUCH LOWER wind speed than
most people would think.  An HONEST manufacturer would volunteer this
information to an otherwise unsuspecting customer for the safety of the
customer, even if it cost him a few sales . . .