The small p-p gearboxes are closer to 10k:1, and I presume the large are
about the same. I would not have thought you could ever back-drive a
p-p, but I believe Gerald. That motor must have been LOUD!
73,
geo - n4ua
> -----Original Message-----
> From: towertalk-bounces@contesting.com [mailto:towertalk-
> bounces@contesting.com] On Behalf Of Keith Dutson
> Sent: Wednesday, April 25, 2007 8:01 PM
> To: TOWERTALK@contesting.com
> Subject: Re: [TowerTalk] Mast slipping
>
> Let's see...
>
> 90 degrees in 5 seconds extrapolates to 360 degrees (1 rev) in 20
seconds,
> or 3 rpm. I understand most of those prop pitch motors have about
1000 to
> 1
> gear reduction, so the motor must have rotated at about 3000 rpm.
Yep,
> that's screaming!
>
> 73, Keith NM5G
>
>
> _____
>
> From: TexasRF@aol.com [mailto:TexasRF@aol.com]
> Sent: Wednesday, April 25, 2007 11:32 AM
> To: kdutson@sbcglobal.net; TOWERTALK@contesting.com
> Subject: Re: [TowerTalk] Mast slipping
>
>
> First hand feedback: a full sized 80m 3-el yagi (1200 #) will windmill
a
> large prop pitch with about 45 mph wind. This is for a very well
balanced
> design with equal element spacing.
>
> You can't imagine how disconcerting it is to be belted off next to one
of
> those big drives and hear it screaming as the antenna rotates 90
degrees
> in
> about five seconds!
>
> I had to scrounge up an original disc brake for the prop pitch motor
to
> hold
> that load in the gusty Texas winds.
>
> Wonder how one calculates twisting torque when the load is balanced?
There
> seems to be a missing bit of information needed to do such a
calculation;
> variation in wind speed over an area of say 100ft in width.
>
> 73,
> Gerald K5GW
> _______________________________________________
>
>
>
> _______________________________________________
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> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
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