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[TowerTalk] Rotator and Antenna Standards

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Subject: [TowerTalk] Rotator and Antenna Standards
From: (Pete Smith)
Date: Mon, 01 Mar 1999 22:01:10 -0500
At 03:18 PM 3/1/1999 EST, wrote:
>>Question for the MEs out there -- how would you combine wind torque and
>>measured inertia/momentum to produce a real number, that could be compared
>>with rotating and braking torque specs to determine if a given rotator will
>>do the job reliably?
> >  
>>73, Pete Smith N4ZR
>In trying to combine wind forces and starting torque needed to overcome
>inertia, it would be relatively easy to look at the combination of the two
>based on a set wind velocity (speed and direction) however there is the crux
>the problem.  In looking at a wind speed, we are approximating the wind and
>the often quoted 70 mph figure is a fastest mile wind which is currently
>phased out as all new wind data is based on 3-second gusts in which 90 mph is
>the new base wind speed.  Even your previous 70 mph numbers had to use Gust
>Effect factors to obtain wind forces.  So our wind forces which get
>approximated as static forces are not static but dynamic.  In addition wind
>can fluctuate greatly over a small area as well, in the national building
>codes they have two different wind loads, one for an entire structure and
>another for individual components of the structure.  All of this really boils
>down to the fact that you can add the 'base' wind load torque created and the
>required starting torque but I doubt this new number will mean anymore to
>world operation then the current 'K' factor which seems to be causing so many

Bill makes a good point.  Virtually any "standard wind environment" is
going to be, at best, just an approximation.  However, since the current K
factor makes no allowance for wind forces at all, I think that any
benchmark that includes both wind and inertial components has to be an

73,  Pete N4ZR
Loud is good

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