Hi! Guys.
G-PTAG engine crank case looks down 0.2 of a degree relative to the Port
side door cill. I am no authority on this but I believe the crank /prop
centre line is 2" higher than the Rotax. I also think there should be 1/2
degree offset but there again it may be 1.5 deg.!, which G-PTAG hasn't got
therefore needing a small tab on the left/port rudder.
I'm interested to know how stiff the rubber is on your engine mount rubbers.
You will note from my examples on the "bin" web site that I had to put the
top rubbers back to front? Don't forget to do this , I would suggest it is
logic which ever type of rubber you have. You need the static engine weight
to pull the back plate ON TO THE RUBBER SPIGOT. The bottom one is OK for
static load as the book instructs. I also made up a couple of the aluminium
retaining bushes at 1/2" larger diameter for the top mounts. Looks much
happier!
Regards
Bob Harrison G-PTAG
Regards
Bob Harrison G-PTAG
> -----Original Message-----
> From: owner-europa@aztec.houxou.com
> Subject: Re: Engine Thrustline
>
>
> Hi, Tom --
>
> > I have a fwf kit for a Jabiru 3300 for the XS and thus far I have little
> > installation info. Does the Rotax kit 4 discuss the engine thrust
> > line? Many aircraft call for a 2 to 3 degree thrust line offset to
> > starboard to compensate for P factor. What is called for with the Rotax
> > engines?
>
> 914 manual says 1.5 deg. to starboard. Determined by a straightedge
> on prop flange, with tick marks 20" on either side of centerline
> (total 40"). Distance from marks to firewall should differ by
> 1-1/16".
>
> > Is there any vertical line offset?
>
> They don't say, but mine came out about zero. It depends upon
> relationship of your thrust centerline with the vertical position of
> the aircraft's CG, probably still (desirably) above the latter for the
> 3300, unlike a high-wing Cessna where engine's gotta point down. I'd
> guess as long it's zero or down a hair, you'll not notice anything in
> flight testing (you don't want immediate pitch up on rapid power
> application - horiz tail alone causes a bit of that). Looks about
> zero on Bob Harrison's, eh Bob?
>
> Enjoy that 3300.
>
> Regards,
> Fred F., A063
>
>
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