|
|
Thanks Dave
That makes sense, particularly for those of us with the damper already.
I suppose I’m also questioning our own vibration and noise from our fwf. I’d be interested to know what others have found.
Our prop is an electric adjustable.
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’ve 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’s between say 6K and 7K rpm.
Its really smooth at 7K but rougher at 6K. Though I’d prefer to run her at around 6K.
There doesn’t 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’d 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:
>
> 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.
>
> Dave Leonard
>
> On Sun, Dec 6, 2020 at 2:28 PM Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
> Thanks Dave.
>
> 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” isolation provided by the damper?
>
> 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 “flexing” forces at play.
> Steve Boese’ science/engineering mind or Lynn Hanover’s hands dirty experience appreciated at this point!
>
> Thanks also to Dave Leonard for what we have learnt from your need for speed, and Neil Unger’s relentless work on gearboxes.
>
> So there being evidence of failure outside of aircraft use, I'll look into another stronger starter ring gear.
>
> 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.
>
> Has there been further word from Tracy or anyone else flying the RD2 or other no-isolator setups?
> Tracy’s initial testing appeared promising but thats now some years back.
>
> Thanks heaps everyone. Couldn't have got this far without your brains, pain, cheque book, experience etc.
>
> Cheers
>
> Steve Izett
>
>
>
>
>
>
>
>
>
> > 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’t 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’ll 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’re 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’m 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
> > >
> > > --
> > > This email has been checked for viruses by Avast antivirus software.
> > > https://www.avast.com/antivirus
> > >
> > >
> > > --
> > > Homepage: http://www.flyrotary.com/
> > > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
> >
> >
> > --
> > Homepage: http://www.flyrotary.com/
> > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
>
>
> --
> Homepage: http://www.flyrotary.com/
> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
|
|