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 09:08:19 +0800
References: <list-1014980@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-1014980@logan.com>
Message-Id: <5200A489-7E56-42BC-8C07-571C4A23CF4E@gmail.com>

Thanks Dave

That makes sense, particularly for those of us with the damper already.

I suppose I=E2=80=99m also questioning our own vibration and noise from =
our fwf. I=E2=80=99d be interested to know what others have found.
Our prop is an electric adjustable.=20
We balanced each blade pretty precisely and then dynamic balanced it at =
6000rpm, and according to the equipment we used we got it was right down =
in the noise at <0.05 inches/sec.
It did require quite a bit of weight to get it balanced and Ive always =
wondered why that was. ~8 X 3/4 inch washers and the nuts and bolts that =
hold them to the spinner backplate at a radius of about 5 inches.
I=E2=80=99ve pondered:
	1. The Engines Rear counterbalance being wrong. But I thought it =
was on the back of the Eccentric Shaft when I got the engine originally, =
and then I purchased and bolted on the flex plate.
	2. The Damper itself, but all the bolts, washers and nuts appear =
symmetrical.
	3. The Prop Hub and Spinner - all appears symmetrical.

I wish I had checked the balance dynamically without the blades and =
spinner to isolate what is causing the need for the weights.

We can certainly hear/feel the difference in flight when we adjust the =
rpm=E2=80=99s between say 6K and 7K rpm.=20
Its really smooth at 7K but rougher at 6K.  Though I=E2=80=99d prefer to =
run her at around 6K.
There doesn=E2=80=99t seem to be a significant change in the fuel =
flow/IAS from using 6K vs 7K. I suppose the equivalent of driving in 3rd =
or 4th gear.
I=E2=80=99d just prefer to lower the wear in case that is significant!

I suppose it's this vibration difference that makes me want to get rid =
of the damper if others have found its not necessary.

Cheers

Steve


> On 7 Dec 2020, at 6:37 am, David Leonard wdleonard@gmail.com =
<flyrotary@lancaironline.net> wrote:
>=20
> My solution was to use an aftermarket flywheel and have it milled down =
a little so that the damper plate could bolt to it.  So I kept the =
damper because 1) it was the easiest approach, 2) I didn't think it =
could hurt.
>=20
> Dave Leonard
>=20
> On Sun, Dec 6, 2020 at 2:28 PM Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
> Thanks Dave.=20
>=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
>=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:
> >=20
> > 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.
> >=20
> > Dave Leonard
> >=20
> > On Sun, Dec 6, 2020, 12:48 AM Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > Hi Charlie
> >=20
> > I thought people moved to the race flywheels because the flex plates =
were cracking.=20
> > 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.
> >=20
> > Thanks
> >=20
> > Steve
> >=20
> >=20
> >=20
> >=20
> >=20
> >=20
> > > On 6 Dec 2020, at 8:58 am, Charlie England ceengland7@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > >=20
> > > On 12/5/2020 6:35 PM, Stephen Izett stephen.izett@gmail.com wrote:
> > >> Hi team
> > >>=20
> > >> 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.
> > >>=20
> > >> 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.
> > >>=20
> > >> 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.
> > >>=20
> > >> Cheers
> > >>=20
> > >> 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.
> > >=20
> > > Charlie
> > >=20
> > > --=20
> > > This email has been checked for viruses by Avast antivirus =
software.
> > > https://www.avast.com/antivirus
> > >=20
> > >=20
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