In a message dated 9/24/2007 2:58:56 AM Eastern Daylight Time,
europa-list@matronics.com writes:
Would you care to share any precise speed measurements (3 GPS runs, max
take off weight, record of altitude, OAT, etc.) ?
My Jabiru buddies are getting soooo discreet when it comes to actual
performance ;-(
Hi Gilles,
Sure, I've done many, many speed measurements, especially lately with all
the flow testing I've been doing on the wings and I'm happy to share my
numbers. Mine is a trigear with an empty weight of 909lbs. The C of G is a
little
over 60". Typically what I see on a 75F day is 134 kts in cruise at 2850 rpm
at 3500' burning 4.6gph according to my Grand Rapids fuel flow meter. One
recent cross country flight I saw a TAS of 148kts at 7500' at the same throttle
setting. This is with a fixed pitch Sensenich hollow carbon prop pitched as
far as I can go and still operate safely out of my 2200' strip, 700' msl, with
two on board, full fuel and baggage. I don't pay much attention to MAP,
though, since there isn't much I can to about it without being turbo
normalized.
I did close off the overflow holes completely on the Jab air intake in an
effort to maximize MAP.
I have flown at 1450 lbs gross on several occasions and I'm still climbing
in the neighborhood of 1200-1300 fpm. If I back off to 2650 RPM, I cruise at
125kts and my fuel burn goes down to 3.8- 4.0 gph. I have worked hard on
getting the mixture well balanced between the cylinders by playing with the
needle
jet and needle setting, as well as the float level in the carby. I''ve also
twisting the carby slightly left from vertical to even out the mixture. I
now have EGT's all within about 40F of each other and my plugs are a nice tan
color. I also am running the Iridium plugs now with great success. This engine
will idle at about 500 rpm with the Iridium plugs and still maintain about
22psi OP. I believe I have a handle on the cooling thing on all but the
hottest days, and then it's only an issue in extended climbs on the #4 cylinder.
FWIW, these are the same days my Rotax buddies also have shown cooling issues
in a variety of different applications, including the Europa. I did fit a
larger oil cooler than what came with the engine. That proved to work very well.
I never see oil temps over 190F, even on the hottest days. Fuel burn is very
comparable to the 912s, too.
I don't know what it is that these other Jabiropa builder/fliers are doing
wrong, though. I would go so far as to say that the Jabiru is superior in a
lot of ways over the 912s, particularly in terms of how smooth the engine runs
and of course, price. Contrary to the blather that has been spread about the
Jabiru/Europa combo on a variety of forums, I firmly believe the Jabiru is a
fine alternative to the Rotax 912s, provided you follow Jabiru
recommendations and undoubtedly it's a hell of a lot cheaper than the 912s on
this side of
the pond. The parts are also considerably cheaper, too. I'm really looking
forward to the day when Airmaster finally releases the new hub that fits the
Sensenich blades.
IMHO, I don't think the Jabiru factory cowl set fitted to the Europa is
going to work very well, though. I think it has to do with the "D" shape of the
intake holes. I think Andy Silvester/Suncoast has the right combo on his cowl
set with the round intake holes, but I think the head cooling ducts he sent
with the engine leave a little bit to be desired. They're made from
fiberglass and they tend to soften from engine heat. That has proven to be a
problem
and one that has caused some minor maintenance issues. I'm not sure the left
duct is the right shape, either. I'm playing with Sonex style sheet metal head
ducts now, but they are proving to be a real bitch to fit their odd shape to
the 4" round inlets. My "proof of concept" version is going to have a lot of
duct tape involved! I should have a left duct fitted later today unless it's
soarable again. ;-) More testing will follow and I suspect that I will run
much cooler even on hot days once I have them fitted. If it works as well as I
anticipate, I'll whip out a final version and probably make a right side
metal duct, too.
The Sonex boys seem to have all the cooling issues licked, so that's the
reason I'm trying what they do in terms of head cooling ducts to achieve a
better balance on the CHT's on really hot days and in extended climbs. Below
90F
I never see CHT's over 280F on either side, though, and usually in the
240-250F range. Jabiru recommends 302F CHT max for extended runs and 348F is
max
for short periods, like in climb. I will see 320F on #4 on a hot day in climb,
but it quickly cools to 285F or so once I establish cruise. The rest stay
below 300F.
And before anybody chimes in and tells me I don't know what I'm talking
about when it comes to the Rotax and so everybody will know I'm not pulling my
Rotax numbers out of the air, I also own an Aeromot AMT 200S Super Ximango
motorglider with a certified 912s installed swinging a Hoffman 3 position prop.
So, I do side by side comparisons regularly and I'm very familiar with the
numbers on both engines. I have about 135 hours now in the Ximango and 117 or
so
in the Europa, so plenty of time to compare numbers. FWIW, I like the 912s,
but it is very complicated compared to the Jabiru and it shakes like hell
when you first crank it up. The Jab is much easier to crank when cold. It just
roars to life after a few swings of the blades without all the shaking and no
choke is ever needed, even on cold days. I think the Jabiru is quieter, too.
We tested it with dB meter and my neighbor's lawn mower is louder than the
Jab at take off power at similar distances.
Graham, in regard to your question, I already sent some Jabiropa guys over
your way a fairly extensive overview of what I've done. Is there something
specific that they need to know? I'm happy to share and I've got tons and tons
of pictures.
Regards,
John Lawton
Whitwell, TN (TN89)
N245E - Flying
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