Graham, you are as succinct as always. Wish I could be.
Jabiru comments:
Disclaimer. As many of you know, I have a love/hate relationship with
every component attached to an aircraft. That said:
After considerable work we have tamed (sort of) the older Jabiru 3300
but it is not a plug and play engine installation in a Europa.
Problems/Solutions:
Cooling:
The lunch boxes on top do not work well. We extended the height,
changed all the baffling and modified both the Andy Sylvest and standard
Jabiru cowl. Opening the inlets to get about a 4-5 inch opening
diameter for inlet air minimum of 120-150 sq inches. Exit air has to be
augmented with the addition of a cowl flap style ramp dropping 4-5
inches below the cowl bottom to get enough draw. To allow sufficient
cooling during climb exit air should be about 400 square inches. Move
the inlets out to get as much prop blast for ground cooling as possible
and consider a movable cowl flap on the bottom air exit...
Oil cooler. Put a real oil cooler on your jab like the new install
manual. It needs it. A $32 JC Whitney cheap oil cooler is not
sufficient. The oil cooler must be ducted for proper cowl operation as
well as proper oil cooler performance.
Carb heat. The extra draw of the cowl bottom causes a significant
change in the air filter box pressures which upsets the Bing carby
momentarily. This can actually kill the engine when entering the
pattern for landing. Passengers don't like when the whirly thing up
front stops. I suggest a larger heat muff to improve the flow to the
airbox.
Intake manifold leaks. The Bing carby is a weak link in the Jab.
Tuning the long intake manifold pipes, ensuring they are sealed can be a
chore and please do check your intake manifolds. Any leak makes for a
poor fuel air mixture. If ever an engine cries out for fuel injection
it is the Jab.
The long and uneven length of tubes and the spider manifold carb
attachment is nice machining but not conducive to even fuel air mixture
distribution with the Bing carburetor metering system. Another part of
the cooling problems is the fuel distribution spider does not allow for
uniform cylinder inlet flow. EGT and CHT helps diagnose this as a
cooling airflow or mixture problem.
Carb. Jabiru has gone through many jet and needle combinations and are
pretty close now, but the fuel consumption of a Jab 3300 is a bit
thirsty (6-6.4 per hour at 2400 (but that is 90 Kts and 7.5-8.5 at 2700
80% power and 127 Kts)) in comparison to other engines of similar power.
Prop, The US distributor recommends the two blade wood Sensenich 62
inch prop. The good folks at Sensenich have a very good ground
adjustable blade for a two blade prop for the 3300. Airmaster is now
using this blade on the Airmaster AP420 for the Jab 3300. The AP420 is
working fine on one Europa in Australia. Longer props give the engine
fits. The torque curve of the jab (which falls off after 2700 RPM)
causes the operator to add throttle to try to absorb the torque, but the
engine just doesn't have it to deliver. So the pilot is generating more
heat for no more performance. Max recommended diameter is 64 inches.
The reason for the shorter prop is the thickness and length of the tip
starts going above .86 Mach and it really stars to wear the blade and
makes that horribly loud whacking sound in flight. The tip drag really
increases above .85M and the drag goes way up and starts vibrations. So
Sensenich has swept the tip on their fixed and ground adjustable props
for the Jab to improve the high speed/rpm prop characteristics, but the
strength of the tip means it must be fairly fat, which makes the Mach
crit fairly low.
Longevity:
In the older Jab engines, we have seen extensive pitting in the cylinder
walls from corrosion. Even at 3 months of winter non flying, consider
fogging the cylinders to prevent this or spin it over every week during
winter.
Cylinder warping: Uneven cooling causes the cylinders to warp a bit.
This is easily found by a differential cylinder pressure check. Expect
this warping to cause a broken ring or two and some scoring in the
cylinder. The cylinders cannot be machined according to the US
distributor and the Jabiru maintenance manual procedures. $750 each
plus you have to remove the opposite cylinder to remove the one which
increases maintenance costs. The front two cylinders can cost you $3000
in parts and labor. I'm just not impressed that the Jabiru can go 500
hours without high maintenance costs.
Calibrate the EGT and CHT with a hand held calibrated instruments. You
will need these to be accurate for engine tuning, and baffle tweaking.
You will be rewarded afterwards.
What I like:
Nice machining. Starts well and runs on AV gas and AV oil. Cheap price
for the power.
The manufacturer has incorporated hydraulic lifters now and new fins for
the cylinders so things are getting better.
What I dislike: Torque curve makes a cruise prop a problem for descent
takeoff performance. Setting the prop for cruise at about 2400 static
on the ground causes a long and lugging engine takeoff. The horsepower
falls off to 100 or less and it shows with two on board on a hot day.
Top speed for a trigear seems to stop at about 135. The engine hits
redline very quick in a dive. It really needs a constant speed prop.
The engine maintenance is not as it was originally sold. The cylinders
cannot be maintained, the heads are basic throw away as are the
cylinders. Corrosion is a problem with the choice of metals. In my
opinion, the cylinders need to be of thicker material for more
stability.
Cooling fins on the cylinders are inadequate. They need to be thinner
and more of them. The firewall forward packages are pretty deficient
but are improving over time.
The heads are square which makes training the airflow around the
cylinder especially the bottom very tough. But there is not enough room
to make them round. Ah compromises.
So, can you fix it? Yes.
Is it worth it? You decide. I don't want to do it again.
An aftermarket firm is making a water cooled heads, but at the cost and
installation, just buy a Rotax as the cost will be similar.
I just want a plug and play firewall forward, and I get it more so with
the Rotax 912S. Speeds of the 912S vs Jab 3300 at cruise are virtually
the same, so I think I'll go with the Rotax lower fuel consumption..
As for alternative engines:
Having experimented with fuel injection on the Rotax 914 I can say if
you love to tinker and don't mind years of work, go for it.
Car engines belong in cars. Subaru, Honda and Mercedes make the finest
engines for high performance autos.
However, an aircraft engine is more akin to a marine engine. Aircraft
fly on torque not just horsepower. Aircraft require high torque and
high power to weight ratios. .5 is a good power to weight ratio to
start, and torque should be about double the HP or the engine needs a
gearbox. The reliability needs to be unquestioned. I really prefer the
whirly thing up front work all the time.
The day they make a car that can be started, warmed up for 15 minutes
and then pull a 3000 pound trailer on to the road and floor it for 15 to
30 minutes, then retard the throttle about 400 RPM and hold 80 mph for
hours, and do it daily for 80,000 miles, I'll put it on an airplane.
Propellers are a Zen art. I have numerous articles, programs etc. for
determining blade efficiencies, but finding someone to build a reliable
blade, that holds up well and meets the speed range of 50 knot takeoff
and 180 knot max speed, on 100 HP forget it. The manufacturing
technology at a reasonable cost is just not out there. So we compromise
on twist, area, and cost. The warp drive is OK, as is the Sensenich.
Constant Speed propeller manufacturers make many hubs that make their
own blades or cover a variety of blade manufacturers, but what works
every time in all conditions falls to only a couple manufacturers and we
have all posted comments on these.
As far as putting more than 120 horses on the Europa I don't like it as
the mounts are not really strong enough for the added weight and power
without modification. The Europa needs longer landing gear to get the
prop clearance for the additional power absorption.
I have found that our little Europa is ideally suited for the 100-120 HP
engine series that are under 200 pounds total with accessories. Keep
the airframe down to about 850-900 pounds empty and this is a hell of an
airplane. Add a constant speed prop and it is even better. So why not
put a simple to install engine on it and make it easy to service.
I prefer to spend my time making the wiring, ducting and engine easy to
remove, so some 5 years later in one weekend, I can hoist the engine off
and change all the hoses, clean and service everything, change the
mounts and put it back on. Then hook up the new fuel hoses and plug the
quick disconnect plugs into the firewall and start it up.
My desire is to get in the air reliably. The decision to experiment
with a one off engine project that is even $10,000 cheaper on the front
is not worth it as I would rather see myself and my clients fly rather
than tinker and suffer engineering setbacks in silence or lament they
didn't get what they wanted in their airplane.
I love to tinker, and am always amazed at the superb craftsmanship of
some of our builders and alternative engine and system manufactures, and
some day they will spend the countless hours necessary to get it all
right. I'll wait for them to make an easy to install firewall forward
package and then I'll recommend it.
Keep it simple, keep it light, keep it reliable and you will fly sooner.
Just my opinion.
Bud Yerly,
N12AY, Classic tri gear, 914, Airmaster, 904 pounds
Custom Flight Creations Inc.
----- Original Message -----
From: GRAHAM SINGLETON<mailto:grahamsingleton@btinternet.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Monday, January 30, 2012 4:46 AM
Subject: Europa-List: Jabiru
Some of you might remember I said I only knew of one successful Jab6
installation? Well I had an interesting conversation with
a guy who's been happy with his for a few years now. Sensenich 2 blade
prop, 3 blades are not ideal on a Jab6 because of
crank resonance issues which I hadn't heard about. There isn't much
useful info about Jabs although must admit I don't look far.
I wonder what the Mach no of the prop tips at 150 knots and 3300 rpm?
Must be going super critical, around .65 ish?
With a wooden prop the blades need to be thicker and that isn't good
for high speed. Are Sensenich using super critical sections?
Graham
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