Mailing List flyrotary@lancaironline.net Message #28197
From: george lendich <lendich@optusnet.com.au>
Subject: Re: [FlyRotary] Counterweight tester (was: Wrong flexplate, right counterweight)
Date: Tue, 6 Dec 2005 08:20:23 +1000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Bill,
I was going to ask for a photo - that would be great!
George (down under)

>          I used a piece of 1" x 1" pine cove molding, 17" long. I drilled
a
> large hole in the center and small holes on either end to accommodate long
> sheet metal screws.
>
>          I oriented the wood to line up with the keyway and the center of
> the counterweight (thick section) so the flywheel would also balance fore
> and aft while the tip of the screw leveled it side-to-side.
>
>          I lined up the center hole with the center hole in the flywheel
> (by eye.) I then used two strips of duct tape (about equal length) to
> attach the wood to the edges of the flywheel.
>
>          When I was checking the automatic counterweight, I used the edge
> of the bench to align the screw tip on the wood with the center of two of
> the bolt holes. I then put the whole rig on the lawn mower blade balancer.
>
>          There is probably a much more precise way of doing all this, but
> this was simple and quick and seemed to be "good enough."
>
>          I'll take a picture tonight if anyone is interested.
>
> At 11:50 PM 12/4/2005, you wrote:
>
> >Bill,
> >I'm guessing
> >1. the timber is firmly attached to the flywheel/flexplate at the
opposite
> >end of the
> >scales or the centre ( centre would be better).
> >2. That the timber itself  (with screws) was balanced e.g equi-distance
each
> >side of the flywheel etc.
> >3. That the timber went through  the centre of the heaviest section of
the
> >flywheel/flexplate (counter weight), which was closest to the scales.
> >
> >Mind you I had to read it a couple of times, but it's a good idea when
> >changing form manual to auto flexplate to check for this.
> >
> >I think I will rig something up to check for myself - thanks for the
tip!!
> >
> >George ( down under)
> >
> > > I bought an RX-8 counterweight and at the same time I bought a '86 to
'91
> > > flexplate. (I thought.) Apparently, I have an RX-8 flexplate instead.
> > >
> > > Thus, if anyone has a spare flexplate that will fit the RD-1C at a
> > > reasonable price, I'd appreciate it.
> > >
> > >  >>>> Simple way to measure the moment of the flywheel and
counterweight
> ><<<
> > >
> > > Since the flexplate was wrong, and there are no numbers on any of the
> > > parts, I wanted to make sure I had the correct counterweight.
> > >
> > > I figured out a simple way to determine if I have the correct
> > > counterweight. I bought a lawnmower blade balancer at the corner
hardware
> > > store. (It is a plastic cone on a spindle.) I put the manual flywheel
from
> > > my RX-8 engine on the balancer. I put a laboratory scale next to the
> > > flywheel. I put a small spirit level on the flywheel center. Using a
strip
> > > of wood with a pair of screws in it, (one just for balance) I leveled
the
> > > flywheel by touching the scale with the tip of one of the screws. I
> >twisted
> > > the screw in and out until the flywheel was perfectly level. The scale
> >read
> > > 5.9 oz, and the screw was 8.5 inches from the center of the flywheel.
> >Thus,
> > > the counterweight built into the flywheel had a moment of 50 in-oz.
> > >
> > > I then set up the auto counter weight the same way. I got 5.76 oz.
With
> > > the 8.5 inch distance to center, this worked out to 49 in-oz.
Considering
> > > the crudeness of the measurement set-up, these numbers are the "same."
> > > Thus, I have the correct counterweight.
> > >
> > > It looks like they sent me a "matching" RX-8 counterweight and
flexplate.
> > >
> > >
> > >
> > >
> > >
> > >
> > > Bill Dube <LED@Killacycle.com>
> > > http://www.killacycle.com/Lights.htm
> > >
> > >
> > >
> > > --
> > > Homepage:  http://www.flyrotary.com/
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> > >
> >
> >
> >
> >--
> >Homepage:  http://www.flyrotary.com/
> >Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
>
> Bill Dube <LED@Killacycle.com>
> http://www.killacycle.com/Lights.htm
>
>
>
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
>


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