Gilles and others,
Thanks for the feedback. As for perceived noise levels for the Jabiru
engine, I can't really offer an explanation as to why it's so quiet! I think
you are expecting the PROPELLER to be noisy due to tip speed at the higher
(than Rotax) peak-rpm speed. Again, with the right prop, this is not an
issue. Jabiru make props at 60" diameter, and admittedly without personally
doing the calcs, the tip speed is around 0.75 mach (ok, prove me wrong!). In
any event, a noisy Jabiru engine is rare, and ALWAYS is due to the propeller
selection and it's interference with the airframe, as in the case of
pushers. We have (as John says) a quiet propeller in the warp drive /
Airmaster combination. Those fitting Warp Drive props to pusher
installations (Titan, etc), get much more propeller noise. With Jabiru's
standard wood prop on their aircraft, a level of 62dB(A) is easily achieved
when measuring a 1000' flypast at full throttle, measured on the ground.
This meets the German standards for aircraft noise which are, I believe,
pretty stringent. To summarise, there is no 'generic' issue with propeller
rpm and noise on the Jabiru engine - it's all about the installation.
I'll also try to clarify your points about break-in and maintenance. The
Jabiru has a simple valve-gear, with tappet / valve clearance adjustment
needed at 50-hour intervals. However, with a new engine it is important to
check these adjustments more frequently in the early stages of operation. We
recommend checks at 5, 10, 15 and 25 hours, then 50, and at 50-hour
intervals. Doing these checks tells owners many important things about their
engine's break-in phase: poor cooling shows-up inside the valve chambers as
burned oil deposits, the lack of oil in the valve gear would indicate a
supply problem, the 'movement' of head torque values over a period indicates
head overheating, and similarly valve clearances changing over a period of
time can indicate heating issues. Admittedly, such signs were somewhat more
common in earlier engines (over 4 years ago), but nowadays it is certainly
the exception to witness these tell-tale signs at any stage in the engine's
life. Nevertheless, we still feel it is important to do the checks, and the
confidence gained in a well-running engine that has started its life in good
health is very important. The adjustments can all be completed in less than
half an hour, and I have never heard of owners complaining about the
process. It's seen as a more of a health-check than a maintenance chore.
I hope to have answered the points raised.
Andy Silvester
Suncoast Sportplanes, Inc.
2003 Mainsail Drive
Naples, FL 34114
Tel: (239) 394 6800 Fax: (239) 394 0726
www.suncoastjabiru.com
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Gilles Thesee
Subject: Re: Europa-List: Re: What engine for my Europa?
<Gilles.Thesee@ac-grenoble.fr>
> Andy's comments about the Jabiru 3300 installation are very interesting
> and informative. John Lawton's comments about the quietness of the Jabiru
> installation are provocative, given the 3000RPM takeoff RPM. Andy, would
> you happen to have any ideas as to why this is so, and what Jabiru does
> to address the observer noise issue?
>
Here are a few data on the Jabiru 2200 direct from DynAero, the French
manufacturer and designer of the MCRs :
- They never had any problems with the Jabiru (except one which was covered
by warranty)
- It is lighter than the 912, which is it's main advantage
- It can't really use it's 80 hp due to the high prop RPM (3300 RPM as
compared to 2300 for the Rotax)
- For the same reasons the observer noise is higher because of the higher
tip mach number.
- It necessitates a real break in period of 50 h, with mineral oil,
adjustments every 5 hours, and much heating.
- They have 250 Rotax flying, and only two Jabiru so they don't have much
flight experience to date.
- They would recommend the Rotax for a private owner and the Jabiru for the
flying clubs, who have a Lycoming culture and would keep their familiar
landmarks with this "mini Lycoming".
Further, flying clubs use the Jabiru powered MCR circa 220 km/h, with a
fixed pitch propeller with medium pitch. This setup gives a performance very
similar to the familiar Robin DR 400.
- DynAero's intentions are to have few Jabiru powered aircraft for the time
being, but with high annual flight time (500 h per year) in order to rapidly
build experience with the engine.
- They have a great faith in this engine.
Regards,
Gilles Thesee
Grenoble, France
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