[TowerTalk] PST61 Rotor Reliability?

Gary Schafer garyschafer at largeriver.net
Mon Dec 11 21:34:23 EST 2017

I have from time to time seen it professed that mounting two antennas on
opposite sides of the mast will equalize the torque supplied by wind.

The only thing mounting on opposite sides of the mast will do is equalize
GRAVITY forces on the mast (that try to bend it over) which will be rather
small differences given only a few inches distance apart.

Torque is rotational. Both antennas are going to exert the same amount of
torque no matter which side of the mast they are on.
What am I missing here?

Gary  K4FMX

> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> Jim Thomson
> Sent: Monday, December 11, 2017 6:38 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] PST61 Rotor Reliability?
> Date: Mon, 11 Dec 2017 00:46:45 -0700
> From: David Gilbert <xdavid at cis-broadband.com>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] PST61 Rotor Reliability?
> <I don't think you read my post.?? A paddle isn't applicable here at
> <all.? In fact, it would make things worse by adding cross sectional
> area
> <to the system.
> <Dave  AB7E
> ###  Are your pair of optibeam yagis even Torque balanced to begin with,
> probably not, since I dont see any form of tq comp used on any
> commercially made yagi.
> If not,your swirling winds will make  your situation even worse.
> That paddle the fellow was talking about is actually called a torque
> compensator.
> If you dont have an equal amount of boom on either side of the mast, it
> will not be
> tq balanced.    If you have more boom on one side of the mast than the
> other side,
> it has been mounted at the center of gravity.   If you do that, you
> require a small tq comp plate
> down at the shorter end of the boom.
> ## method 2 is to mount the boom to mast... dead center in the middle of
> the boom. Then
> use a small counter weight at the light end of the boom.  Ditto with
> both yagis.
> ##  with 2 yagis on a mast, they need to be mounted on opposite sides of
> the mast.
> ##  do all of the above, and most of your issues will be alleviated.
> ##  I thought that prosistel made bigger rotors like the 71  and the
> 110 / 115 ??
> ##  My SMALL k7nv PP is good for 1250 ft lbs of tq, thats 15,000  inch
> lbs of rotating tq.
> Its lighter than my M2  OR-2800.   OR-2800 only has  233 ft lbs of tq  =
> 2800 inch lbs.
> ###  on a PP, the final big gear is meshed,and driven by 3 smaller
> gears, every 120 degs.
> PP also come in the medium and large size.
> ##  are u saying your swirling winds are essentially blowing in 2
> directions at once, like N at
> one end of boom, and S at other end of boom ??   With the boom oriented
> E-W.   If that's the
> case, you have a real serious problem.  And any TQ imbalance will make
> it even worse, a lot worse.
> Jim   VE7RF
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