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Message-Id: <4.3.1.0.20051205073311.02080450@mail.chisp.net>
Date: Mon, 05 Dec 2005 07:49:07 -0700
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
From: "BillDube@killacycle.com" <billdube@killacycle.com>
Subject: Counterweight tester (was: Wrong flexplate, right
  counterweight)
In-Reply-To: <list-863496@logan.com>
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         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/
> > Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
> >
>
>
>
>--
>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