Today's Message Index:
----------------------
1. 04:02 AM - Re: Fw: RV4-List: Fixed Prop Balancing (John)
Message 1
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fw: RV4-List: Fixed Prop Balancing |
--> Engines-List message posted by: John <john-h@ihug.com.au>
Hi Gene
Hi from Australia.
I have a wooden prop on my Australian factory built Jabiru aircraft the
engine is a Jabiru 4 stroke flat four direct drive as is yours.
the factory once explained to me that tight prop bolts ant the only thing to
check.
remember the prop is in effect the flywheel of your engine and is constantly
accelerating and decelerating with each piston firing pulse.
the inertia in the mass of the prop is trying to smoothen this out.
my prop is attached as yours probably is with an bolts and Bellville
washers.
also metal locating bushes that resemble a top hat turned on its side
passing through the prop flange and into the soft wooden prop.
the bolts pass through the whole lot on to the front compression plate.
if these bobbins (being harder than wood) slog out even slightly and the
holes in the prop become elongated then the prop will whip back and forth
with the power pulses and can cause a lot of vibration as well as a broken
crank.
I hope this is of use I have trouble explaining things some time.
Regards John Hodges
----- Original Message -----
From: "Gene Smith" <esmith6@satx.rr.com>
Subject: Engines-List: Fw: RV4-List: Fixed Prop Balancing
> --> Engines-List message posted by: "Gene Smith" <esmith6@satx.rr.com>
>
>
> ----- Original Message -----
> From: "Gene Smith" <esmith6@satx.rr.com>
> To: "rv4-list" <rv4-list@matronics.com>
> Subject: RV4-List: Fixed Prop Balancing
>
>
> > --> RV4-List message posted by: "Gene Smith" <esmith6@satx.rr.com>
> >
> > Educate me someone.........Getting some increased vibration on my RV-4,
> and I am concerned......This is a Sensenich fixed with no damage or
strikes,
> and hasn't been re-pitched or worked on since new...... Not even a rock
pock
> mark......Bolts are tight and torqued......It is installed on a Lycoming
160
> HP engine with about 400 hours on the prop, and 1300 hours on the engine.
> >
> > If I hire "prop men" to come out and check it, what is their
> procedure?......Do they balance it on the aircraft with the engine
> running?......Pull it and rotate it on some machine like for auto
> wheels?......How do they check the crankshaft to see if it is the
> problem?......Do they install weights, and if so, how and where do they
> mount them?
> >
> > Would appreciate any info from you folks that have experience in this
>
area..........................CHEERS!!!!.................................Gen
> e Smith.
> >
> >
>
>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|