Hi! All.
Just putting my nose in here since I'm very sensitive about Propeller
Harmonics. IMHO there is insufficient effort made to assess the whereabouts
of this phenomenen in the RPM range. I know where mine is because MT
Propellers have produced the necessary analysis resulting in an "avoid
continious range" of 2150 to 2250. It will be different for each prop
type/engine combination but if ignored can have dramatic failure
implications. William does right to get out of the vibration range but I
think it may be the RPM factor that is the real item to avoid not the load?
Just food for thought!
Regards
Bob Harrison G-PTAG Europa MKI 337/Jabiru 3300 #084 MT CS approx 400 hours.
----- Original Message -----
From: "William Mills" <combined.merchants@virgin.net>
Subject: Re: Europa-List: Worrying conundrum
<combined.merchants@virgin.net>
>
> I do the same as Javier; increase power, or increase VP pitch to load the
> engine. Always clears the vibration. I think it is back-lash in the
> gearbox.
> William
> ----- Original Message -----
> From: "Barahona Alonso, Francisco Javier" <Javier.Barahona@aeasa.com>
> To: <europa-list@matronics.com>
> Subject: RE: Europa-List: Worrying conundrum
>
>
> <Javier.Barahona@aeasa.com>
> >
> > I have observed a similar vibration in some occasions just after
take-off,
> when reducing gas from full power. It happens around 4800 rpm. What I do
is
> to reduce a bit more and then increase it again if needed. So the
vibration
> disappears.
> >
> > I do not think it is related with carb icing. I fly in Spain with high
> temperatures. My opinion is that it is a kind of resonance related with
the
> engine revolutions and plane attitude.
> >
> > Best regards
> >
> > Javier
> >
> > Classic 187, 912 UL
> >
> >
> > <peterdavis@ntlworld.com> writes:
> > > <peterdavis@ntlworld.com>
> > >
> > > I crave people's indulgence with this one.
> > >
> > > Last weekend I experienced a very slight vibration that lasted for a
> > > few
> > > minutes whilst flying. It was just audible and just noticeable
> > > through the
> > > control column. The frequency at 4800 rpm was about 2 or 3 beats per
> > > second
> > > and was very reminiscent of "interference" or "sympathetic"
> > > vibration that
> > > might occur if part of the 'plane was vibrating in sync. with the
> > > engine.
> > >
> >
> >
>
>
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