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[TowerTalk] Rotators

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Subject: [TowerTalk] Rotators
From: (
Date: Tue, 3 Jun 1997 16:07:00 -0400 (EDT)
In a message dated 97-06-03 14:27:56 EDT, you write:

> I'm curious.  Obviously the prop pitch was not designed to be a rotor.
>  What is it?  Is it really a propeller pitch motor?  If so, off what?
>  Must be one big airplane.
    Yes, as a matter of fact it is, or was. It's the motor and transmission
that changed the pitch of the propellers in B-26's, B-29's, etc. When you
look at a propeller driven airplane (or aeroplane for you Brits) engine,
right in the middle of the propeller hub is a kind of a can-shaped object
that sticks out. This is the motor cover of the prop pitch. 

     These things are works of art inside. The precision and military
specifications that they were built to is awesome. I'd hate to think what the
cost to manufacture one of these would be today. They have a 9 or 11,000 to 1
gear reduction but I don't remember what any specific torque figure is.
Needless to say, this thing will turn your house without batting an eyelash.
You can imagine the forces on a maximum RPM 4-bladed propeller on a fully
loaded WW2 bomber and what it would take to change the pitch on the props
during flight.

      These units will typically last 15-25 years in a ham installation with
little or no maintenance. Stuck brake? Forget it. Won't turn your array into
the wind? Piece of cake. This is the piece-de-resistance of rotators. Even if
you bought one of K6NA's units for $1800.00, a 20-year service life has only
cost you $90.00 per year. You'll have purchased/repaired 3-4 TailTwisters in
that span. 

     Since it's been 50 years since they hit the surplus market, you can
imagine that the supply is dwindling. Ten years ago you could pick one up at
a flea market for $100.00 but not anymore.

73,  Steve  K7LXC

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