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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-871000@logan.com>
Subject: Re: [FlyRotary] Re: V shape Apex Seal Slots?
Date: Sat, 16 Apr 2005 08:28:36 +1000
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Lynn,
Good info on balancing the two rotors.
Does the rotor have to balanced within itself for a best balancing outcome.
I'm doing a 'single rotor' and was wondering if I need to go that far.
George ( down under)

> It all sounds good to me. The Japs are anal about a lot of things, and
> getting the engine smoother than any piston engine was way high on the
list. It has
> a built in rocking couple problem, and a built in torque amplitude
problem. So
> the counter weights take out the rocking couple, and the 40 pound flywheel
> evens out the torque pulses. Presto, smoother than any piston engine.
>
> So, if you have two good rotors and they have different weights, what to
do?
>
> Build one hell of a sensitive scale. Then use your drill press to remove
tiny
> amounts of steel from the heavy rotor, until both are the same weight. Use
> the counterweights from the lighter rotor's engine.
>
> The scale can be anything stiff. Like a 2X4 or pieces of square tubing or
> round tubing, maybe 6 feet long. The pivot is to be two sharpened bolts
through
> the (whatever) bar. Then two bent up hangers. Cut two steel 3/8" rods the
same
> length to start with. Sharpen one end to a fine point, and bend that end
into
> a 180 with a radius big enough to clear the end of the bar. The other end
can
> be just a hook to grab the rotor through an oil opening, or a real nice
flat
> 90 to sit in the bearing hole.
>
> If your bar is wood nail a scrap of steel plate to each end in exactly the
> same place.
> Put a punch mark on one plate or on one end of the square stock close to
the
> end. Make the hangers just long enough so that a rotor on each one will
just
> clear the floor, or bench.
>
> With just the hangers, hang one on where your punch mark is installed.
Hang
> the other in a location that just balances the scale. Reverse the hangers
to be
> sure they weigh the same. Grind off as required. Mark the location of the
> second hanger, and make a punch mark for that one. The punch make is to
make a
> location that can be found every time, so make just a mark, don't beat a
big
> depression. The sharp points and hard surfaces generate a near zero
friction
> pivot point.
>
> Support the pivot bolt ends on a flat plate between jack stands, or cement
> blocks, whatever.
> Hang any two rotors. Dump pennies or (If its close) paper clips to
balance.
> Then reverse the hangers with the rotors left on them to be sure the
answer is
> the same.
> Drill a bit (use a drill stop) from the corner area (look where the
factory
> did it) and reweigh. After two passes, drill a set on the opposite side of
the
> rotor.
>
> If you think it through, you can build a scale that can "see" a paper
clip.
> And that is close enough. You will notice that the fans must be off, and
the
> doors closed.
>
> Lynn E. Hanover
>
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