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
In a message dated 4/25/2007 11:12:26 A.M. Central Daylight Time,
kdutson@sbcglobal.net writes:
I don't think the drive can be back-driven. It's just that you would need
about 30,000 in-lbs of torque to break anything.
73, Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Lux
Sent: Wednesday, April 25, 2007 12:21 AM
To: Kurt Andress; TOWERTALK@contesting.com
Subject: Re: [TowerTalk] Mast slipping
At 06:14 PM 4/24/2007, Kurt Andress wrote:
>Pinning the mast to the clamp doesn't void the warranty, because the
>prop pitch gear train (at least like I build them) can't be broken.
I assume that's mostly because the gear train is a back-drivable spur or
planetary set as opposed to a worm/pinion? If you overload it, it just turns
the motor?
Jim, W6RMK
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