Mailing List flyrotary@lancaironline.net Message #13893
From: Fred Osborn <fosborn@infowest.com>
Subject: Single Rotor
Date: Wed, 15 Dec 2004 07:38:48 -0700
To: <flyrotary@lancaironline.net>
In a message dated 12/15/2004 Fred Osborn wrote:

<< I plan on using a 89-92 na rotor which is 8 oz. lighter that my '87 rotors in

  << the hope that I can get to a balanced assembly by removing a small amount
  << of weight from my '87 balance weights. >>

In a subsequent message dated 12/15/2004 07:40 EST Lehanover@aol.com wrote:

< I thought that weight would have to be added in order to balance a 9 pound
< rotor. Is that not the case.

According to the RB rotor weight charts my 87 NA rotors weigh 10.04#. I had to
add approx. 4oz. to each balance weight to get to a crude assembly balance on
a pair of parallel level round bars. The 89 NA rotor weighs 9.54#. Thus the hope
that 8oz. lower rotor weight will bring me close to a static balance condition.
Then I will have to go through a rather complex measure procedure to get close
to a dynamic balance. As far as I have been able to determine no one is setup to
do a spinning dynamic balance on a single rotor.

<I was thinking of adding a groove in the main bearing to supply cooling oil
<to the rotor interior, rather than trying to drill a hole in the crank. Does
<that sound plausable?

I never considered it. How would you direct the cooling oil flow into the rotor
pockets? Drilling in the crank is relatively easy once you get through the
hardened surface. That first 1/8" is a real tool buster.

< Using the front stationary gear sounds to me to be the way to go. With the
< large direct oil drainback at the bottom of the stationary gear.

Yes, you need the front stationary gear to position all of the front needle
bearing stuff anyway and it's much lighter than the rear gear.

Lynn, it sounds like you are seriously considering a single rotor engine. Did I miss
something in a previous post? What would you plan to do for an e-shaft? I cut up
a 13B part, did some crude machining, and shrink fit the cut down front part into
a pocket in the rear rotor journal. Definitely not a flight article but it turns smooth
in a single rotor buildup so I can try doing some other things I'm interested in trying.

Please all, forgive my crude editing, I'm just beginning to attempt to learn to post
to this forum.

Fred Osborn

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