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Thanks Charlie
Steve
> On 8 Dec 2020, at 5:03 am, Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net> wrote:
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>
>
> On Mon, Dec 7, 2020 at 8:20 AM Ernest Christley echristley@att.net <flyrotary@lancaironline.net> wrote:
> The temperature in that area will range from around 180F to well below freezing on a cold night, resulting in a lot of differential expansion. Epoxy is basically plastic. It is going to soften in use, when its strength is needed most.
>
> This is something I'd probably try, but I wouldn't bet money that it would work.
>
> On Monday, December 7, 2020, 5:29:25 AM EST, Le Roux Breytenbach breytenbachleroux@gmail.com <flyrotary@lancaironline.net> wrote:
>
>
>
> Hi : It was mentioned on P.L. newsletter a couple of years ago - what if the flexplate center are reinforced with say 6 layers of carbonfiber on both sides ?
> The carbonfiber can be vacumebag and really good cured if doiing it from both sides.
> The carbonfiber will lock from both sides face to face threw the bigger holes and will secure more than just on the metal itself.
> Doiing the flexplate as a complete unit and then just cut and machine the holes.
> It will be ridged and light as well and counter the gyroscopic forces ect.that leads to cracks from the holes
> Then the rubber dampener could still be put in place.
> I am goiing to replace the center on this clutchplate with a rubber dampener
>
>
>
> Regards Le Roux
>
>
> Sent from my iPhone
> Le Roux Breytenbach
>
> > On 07 Dec 2020, at 09:07, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
> >
> > See below what Tracy wrote in Feb 2012.
> > Also found a note in the archive where Tracy mentions only producing a few of the RD-2 boxes before retiring.
> > So how many hours does Tracy’s RV4 with the damper removed now have on it.
> > Sounds from what some have said that he may have installed this mod to his 20B RV8 which may have more time, however thats a 3 rotor. What difference would that make I wonder?
> > I take it the torque reversal and pulses will be the same magnitude but the sum of those pulses may have a different outcome for anything connected.
> >
> > Cheers
> >
> > Steve Izett
> >
> >
> > email from Tracy back in Feb 2012 -
> > "Finally got around to flight testing the aftermarket flywheel setup for the RWS redrive.
> >
> > The cracked flexplate issue some builders experienced came up at the same time as my CNC source for input shafts lost the ability to make them anymore due to loss of specialized spline making machinery. Since I had to line up a new source I took this opportunity to review the design from the input shaft back to the engine. Because the damper has been such an expensive and labor intensive part, it was looked at as well. As a result, there have been enough changes to warrant a change in the name so the new drives will be RD-2B & RD-2C.
> >
> > In rethinking the drive I had the thought that since the relatively low frequency primary resonance range of the drive train is taken care of by the system lash, that left only the high frequency harmonics that the damper is responsible for. This high range is the factor that creates the red zone in rpm ranges found on some certified engines and metal prop combinations. As far as I know, no one has used a metal prop on an RD-1x drive so I decided that it was an unneeded requirement. The new design has no damper at all and consequently it has a "No Metal Propeller" restriction.
> >
> > Replacing the damper is a flanged spline that is bolted directly to the flywheel using the same bolts (longer bolts required) that attach the flywheel to the counterweight. The spline is a different spec (15 splines instead of 30) so it is not compatible with the RD-1 damper but the new shaft itself is backward compatible with the remainder of the drive. I retrofitted the same RD-1C that was on my RV-4 for these tests.
> >
> > The flywheel was an aluminum racing flywheel with the replaceable iron friction surface unbolted and removed. Really looks pretty and professional compared to the flexplate. Any of the aftermarket RX-7 & RX-8 racing flywheels (steel or aluminum) that utilize the auto counterweight may be used.
> >
> > As David Leonard found, these flywheels place the ring gear about .2" closer to the engine than the flexplate. To compensate, I milled .2" off the front surface of the adapter plate where the starter mounts. No changes were needed to the starter itself. I did not bother to grind the lead-in bevel on the ring gear teeth as discussed earlier. Starter engagement was smooth anyway.
> >
> > The RV-4 drive had over 700 hours on it and everything looked beautiful inside. No signs of wear other than a shallow groove (~.002") on the input shaft where the 1mm thrust bearing race between the two needle bearings rides. Others have reported more than this in fewer hours so this is an area to inspect carefully. The new input shaft is a harder alloy (post machining through hardened 4340) than the the RD-1 which was pre hardened 4140. This should reduce the wear in this area. The old flexplate with over 1000 hours was still crack free. The input shaft oil seal still looked and felt new so it was not replaced as planed. Others have reported these leaking in much fewer hours. Don't know the reason but I suspect that oil temperatures out of range may be a factor. NEVER allow oil temps to exceed redline. If they go higher, back off the power then land and correct the cooling system.
> >
> > Only 1 hour of flight testing so far but all indications were good. Operated the engine through the full range of rpm up to 7100 looking for tell-tale signs of resonance. I was sort of expecting to feel, sense or hear some indication of increased harshness in the drive with no rubber anywhere in the system but if anything, it felt smoother. There was none of the 'Waaa --- Waaa' warbling sound (like a twin engine with the engines out of sync) that I had with the Ross drive years ago. So far I'm very satisfied with the results but it's still early in the tests.”
> >
> >
> >
> >
> >
> >> On 7 Dec 2020, at 9:47 am, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
> >>
> >> Thanks Lynn.
> >>
> >> Steve
> >>
> >>
> >>>> On 7 Dec 2020, at 9:04 am, lehanover lehanover@aol.com <flyrotary@lancaironline.net> wrote:
> >>>
> >>> 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.
> >>>
> >>> 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.
> >>> 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.
> >>>
> >>> 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.
> >>>
> >>> 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.
> >>>
> >>> The teem had a very competent engineer. My hands are still dirty............... Lynn E. Hanover
> >>>
> >>> In a message dated 12/6/2020 5:28:22 PM Eastern Standard Time, flyrotary@lancaironline.net writes:
> >>>
> >>> 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
> FWIW, in the car, the torque converter seems to be bolted to the flexplate using the same holes that Tracy's adapter uses. Looking at the RX8 service manual, there may be a narrow sheet metal adapter ring between the flex plate bolt circle and the torque converter, but not much else in the way of structural reinforcement. (Of course, the torque converter housing itself may act as stiffener.) It *seems* logical to me that if there were going to be stress cracks caused by flying the assembly, they'd show up in the aluminum adapter plate before the steel flex plate. And cracking usually starts where there's a 'stress riser'; a notch or deep scratch in an edge. The only plates I've observed have un-dressed, sharp edged punched holes where the cracks seem to originate. I don't know whether it will help, but I attacked my uncracked flex plate with a die grinder & files to clean up all the accessible edges of holes, etc, as we do with any aluminum parts, before assembling everything.
>
> Again, just my opinion, but I think that the real benefit of the extra mass of a flywheel is pulse isolation from the gearbox.
>
> Charlie
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