From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] RD1-C damper
Date: Mon, 7 Dec 2020 09:47:05 +0800
References: <list-1015241@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-1015241@logan.com>
Message-Id: <7D9C4080-6A99-4232-B2AF-2A7A4F29BF11@gmail.com>

Thanks Lynn.

Steve


> On 7 Dec 2020, at 9:04 am, lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
>=20
> If you have picked up a stock manual transmission flywheel for a =
rotary, you must know that "Houston we have a problem". So the worst =
pick for a car engine becomes the best pick for smoothness at idle. That =
flywheel is the answer. The less flywheel effect available the more =
powerful the reversals near idle. The more powerful the reversals the =
shorter the flex plate life. The flex plate drives the car through a =
hydraulic damper. So it is with the aircraft. No damper, short life. =
There are companies who make little tiny shock absorbers. I thought that =
4 such shocks on a racing flywheel pushing a driven disc should do the =
job. Even stock flex plates from piston powered cars get cracks. Few =
fail completely.
> =20
> I think Tracy's pucks are adequate. Just double up the flex plate to =
just outboard of the puck housings. No welding. Use nuts and bolts.  It =
also adds actual flywheel effect which reduces the stress. =20
> For the racer I made a steel button flywheel. Just large enough to =
support a 2 disc 5 1/4" clutch. I bolted this on over the stock flex =
plate. The flex plate was just used to start the engine and nothing =
else. I turned down the face of the counter weight so as to provide a =
taller spigot to locate the flex plate and the flywheel. Piece of cake.=20=

> =20
> The racer used a straight cut gear dog ring style gear box from Saenz =
in Argentina. The gears had enough clearance so as to agree with various =
RPMs. As on start up form a stand still the RPMs would drop below 2,200 =
and the car sounded like a Brush Hog running over a pile of hammer =
heads. That is what you want to avoid.=20
> =20
> Also when unloaded even at higher RPM. The same thing. So when =
feathering the throttle like in third gear. When the engine is not =
driving the wheels and the wheels are not driving the engine. Maybe as =
on final you might get into this situation. So a bit more power, or, a =
bit less power will save the day.
> =20
> The teem had a very competent engineer. My hands are still =
dirty............... Lynn E. Hanover =20
> =20
> In a message dated 12/6/2020 5:28:22 PM Eastern Standard Time, =
flyrotary@lancaironline.net writes:
> =20
> Thanks Dave.
> =20
> Did you do away with your damper after your flax plate =
disintegrated/failed over time, or was this still before Tracy changed =
his mind about the need for the "higher frequency=E2=80=9D isolation =
provided by the damper?
> =20
> I was trying to think about the forces at work on that thin steel =
plate apart from the torque of your boosted 300 hp.
> I was wondering about the gyroscopic (is that the right word) force =
created by that extra mass bolted to it, travelling at much higher =
velocity, and then being asked to change direction with the subsequent =
=E2=80=9Cflexing=E2=80=9D forces at play.
> Steve Boese=E2=80=99 science/engineering mind or Lynn Hanover=E2=80=99s =
hands dirty experience appreciated at this point!
> =20
> Thanks also to Dave Leonard for what we have learnt from your need for =
speed, and Neil Unger=E2=80=99s relentless work on gearboxes.
> =20
> So there being evidence of failure outside of aircraft use, I'll look =
into another stronger starter ring gear.
> =20
> BUT more to the point. what experience do we now have of removing the =
damper altogether?
> I thought this was the important question, because if not required, =
appears to save significant: weight, cost, and maintenance.
> =20
> Has there been further word from Tracy or anyone else flying the RD2 =
or other no-isolator setups?
> Tracy=E2=80=99s initial testing appeared promising but thats now some =
years back.
> =20
> Thanks heaps everyone. Couldn't have got this far without your brains, =
pain, cheque book, experience etc.
> =20
> Cheers
> =20
> Steve Izett
> =20
> =20
> =20
> =20
> =20
> =20
> =20
> =20
> =20
> > On 7 Dec 2020, at 12:52 am, David Leonard wdleonard@gmail.com =
<flyrotary@lancaironline.net> wrote:
> >
> > Steve, you are right.  The Issue is cracking og the auto-tranny flex =
plate.  Mine failed entirely.  I highly recommend making the change =
sooner rather than later.
> >
> > Dave Leonard
> >
> > On Sun, Dec 6, 2020, 12:48 AM Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > Hi Charlie
> >
> > I thought people moved to the race flywheels because the flex plates =
were cracking.
> > I hadn=E2=80=99t heard of the Engine/Drive/Prop needing a flywheel =
mass.
> > I found some info on the forum archive but nothing to draw it all =
together.
> > I=E2=80=99ll have a good look at the flexplate when I pull the drive =
and check for cracking, but unless I hear otherwise I plan to reuse the =
flex plate.
> >
> > Thanks
> >
> > Steve
> >
> >
> >
> >
> >
> >
> > > On 6 Dec 2020, at 8:58 am, Charlie England ceengland7@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > >
> > > On 12/5/2020 6:35 PM, Stephen Izett stephen.izett@gmail.com wrote:
> > >> Hi team
> > >>
> > >> Having completed phase #1 testing of the Glasair Super IIRG power =
by Renesis and RD1-C redrive, I=E2=80=99re going to pull the redrive for =
its 25 hourly initial inspection.
> > >>
> > >> Tracy deleted the damper assembly from the last rendition of his =
design and I=E2=80=99m considering removing ours by creating a new =
adapter plate from the existing splined
> > >> part that is currently riveted to the damper and adding some =
longer bolts and spacers.
> > >>
> > >> Has anyone heard anything further in regard to RD receives with =
the damper removed?
> > >> Has Tracy given any further updatess?
> > >> All I have read was after initial tests some years ago.
> > >>
> > >> Cheers
> > >>
> > >> Steve.
> > > Best I remember is that you need either an aluminum or steel =
racing flywheel, to get more mass on the engine side of the system.  =
IIRC, it's also limited to low mass (wood, etc) propellers. The ones he =
sold had a different input shaft, but I think Dave Leonard modified his =
RD1-C & to use a steel racing flywheel which was only slightly heavier =
than the aluminum version. Search for Dave's posts, if he doesn't chime =
in. I've been wondering if Guibo/Rototflex couplers could be a viable =
alternative to the aluminum plate/rubber discs. Probably would weigh =
more, and definitely cost more.
> > >
> > > Charlie
> > >
> > > --
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> > >
> > >
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