You might think that the slipper clutch is not there for absorbing the
vibration however.
912S / No slipper clutch plus MT prop Bad vibes.
912S / Slipper clutch + MT prop real smooth.
I am told the Inertia of the MT prop is within limits (6000 kgcm2 is the max
permissible). The prop used was a special three blade designed for the
higher cruise speeds of the MCR range.
Vibration when reducing power from memory. Not at all power settings.
I have an Arplast PV50 - pretty smooth at most RPMs. Slightly less smooth
around 4350 RPM. 200+ hours plus and never dynamically balanced but I do
mean to do that soon.
Jerry
LTS@avnet.co.uk
www.avnet.co.uk/touchdown
----- Original Message -----
From: "Duncan McFadyean" <ami@mcfadyean.freeserve.co.uk>
Subject: Re: Flying: Performance: Speed kit.
> The slipper clutch is not there to absorb vibration (the "dog" clutch does
> that). Although in extremis it would. I wonder whether the inertia of the
> MT prop exceeds that which the engine/gearbox has been designed to take (
> or, more likely, has been successful with using lighter props.).
>
> Duncan McFadyean
> ----- Original Message -----
> From: "LTS" <lts@avnet.co.uk>
> Subject: Re: Flying: Performance: Speed kit.
>
>
> > I have just learnt that the owner of a 912S fitted with an MT problems
had
> > suffered vibrations from day one, much to everyone's surprise.
Eventually
> it
> > was discovered that the 912S had not been fitted with a slipper clutch
> > despite one having been ordered and paid for. That particular Rotax
dealer
> > is no longer a Rotax dealer.
> >
> > Jerry
> > LTS@avnet.co.uk
> > www.avnet.co.uk/touchdown
> > ----- Original Message -----
> > From: "Peter Zutrauen" <peterz@zutrasoft.com>
> > Cc: <europa@avnet.co.uk>
> > Subject: RE: Flying: Performance: Speed kit.
> >
> >
> > > Another question from the uninitiated:
> > >
> > > I wonder, are the "crankshaft oscillation" and resonant RPM's less
> > critical
> > > on a geared engine like the rotax vs. a direct-drive Jabiru? Are they
> > > significant at all? I would imagine that the gear-train filters much
of
> it
> > > out? Or does the gear backlash etc. set the system up for some worse
> > > resonance's? I assume the former from Tony's subsequent reply?
> > >
> > > Cheers & and Holiday Wishes,
> > > Pete
> > >
> > > -----Original Message-----
> > > Cc: 72016.3721@compuserve.com; europa@avnet.co.uk
> > > Subject: Re: Flying: Performance: Speed kit.
> > >
> > >
> > > Hi! Mike.
> > > MT Propellers ,in my case supplied the propeller
> > > kit fully balanced, however they insisted that to
> > > maintain warranty conditions it must be supplied
> > > back to them within 50 hours for strain gauge and
> > > dynamic balance tests with the particular engine
> > > combination to identify any resonant RPM's over
> > > the full range of operation.
> > > This now completed a "non-flying" peak resonant
> > > range between 2150 rpm and 2400 rpm has shown to
> > > be present, and they are recommending not to
> > > cruise in that range if possible.
> > > I guess if I can't live with that it means
> > > another trip back to the factory for flight
> > > testing to try to narrow the non- useable range.
> > > The point about this is that simple balance isn't
> > > the full story and further strain gauge testing
> > > needs to be carried out to do the job in a
> > > professional manner. Only with that test can it
> > > be established what crankshaft oscillation is
> > > taking place, allowing you to select the most
> > > engine /propeller friendly flying.
> > > Best regards
> > > Bob Harrison
> > > G-PTAG Europa MKI /Jabiru 3300
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Quoting DuaneFamly@aol.com:
> > >
> > > > Please excuse a dumb question.
> > > >
> > > > How do you know you have an out of balance
> > > powerplant setup? If it is
> > > > "really" out and you start the engine, can you
> > > do damage before being
> > > > able to
> > > > shut it down?
> > > >
> > > > Mike Duane, San Jose (soon to be Redding)
> > > California
> > > > Lurking for a long time but hope to build soon.
> > > >
> > > __________________________________________________
> > > ____________________
> > > > The Europa List is supported by Aviators
> > > Network UK - info@avnet.co.uk
> > > >
> > >
> > >
> > > -------------------------------------------------
> > > This mail sent through UK Online webmail
> >
> >
> >
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