Hi Fred,
Yeah, we're in the murky world of manufacturer's figures and the difference
between them and real life. Perhaps surprisingly, many owners' often
aircraft exceed manufacturers airframe figures because they shoe-horn bigger
engines into them! I think the Sonex was originally designed for the VW and
actually flies very well on the Jabiru 85hp engine. Notwithstanding, many
'rev-heads' (!) use the 120 hp engine and of course it goes faster.
The USA Light Sport Aircraft rule requires a maximum 120kts 'at the
manufacturer's stated maximum continuous rpm' and, since the Jabiru 3300 has
a max continuous PUBLISHED rpm of 2750 it's easy to see how the aircraft
will go faster at higher rpm. I know of Sonex owners who prefer to cruise at
3000 - 3100 rpm and we work with them to get mixture settings optimized for
this speed. In case of continued debate about the '2750' figure from Jabiru,
it was published when the 3300 came out and never revised in print. Since
then, we are told by Jabiru that a figure 'more like 3100' rpm should be
used for max continuous operation (they have run 50-hours non-stop at 3300
rpm on the dyno. for certification without issue), but they chose to leave
the 2750 figure in print as it helps some manufacturers (like Esqual) obtain
their 120kts at 2750 within the LSA market.
I recall the original posting (more or less) said the Jabiru can't supply
enough power at higher cruise speeds with its prop size, and I maintain
that, on experience, I'm not aware of people turning away from the Jabiru on
slick - aircraft types because they are unhappy with high-speed performance.
Far from it. Ultimately, it's all about the propeller design and efficiency
and, while I accept that a bigger prop turning slower does have a
theoretical advantage, we don't see it as a limitation for the Jabiru engine
at all.
It's also a fact that some aircraft manufacturers suppress the Jabiru's
capabilities in favor of Rotax because they make more money selling a Rotax
than a Jabiru. It's a cruel world....
OK, we agree to differ, but thanks for giving me the chance to comment.
Andy
Suncoast Sportplanes, Inc.
www.suncoastjabiru.com
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Fred Fillinger
Subject: Re: Europa-List: engines
>
> Pulsar, Rand KR-2, Sonex, Esqual, Dragonfly and others
> of similar design and performance. Speeds between 45 kts
> and 160 kts (cruise).
Most of these planes are lighter than a Europa. Pulsar says
the 914 will go faster than the Jabiru 3300, by 18 mph.
Esqual does not claim 160k cruise. In fact, their web site
says that for the new FAA rules on light sport aircraft re
120k, well that's cruise speed exactly. The LSA rules say
top speed, so they don't understand simple rules. Sonex
doesn't claim 160k cruise. Sales brochure speeds are always
overstated anyway. I think there's a kitplane exception in
our mail and wire fraud statutes. :-)
Reg,
Fred F.
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