Today's Message Index:
----------------------
1. 01:19 AM - Re: Re: Gear (Paul Mulwitz)
2. 04:33 AM - Re: Jabiru 3300 cooling and noise (DaveG601XL)
3. 05:58 AM - Re: Re: Jabiru 3300 cooling and noise (Mark Hubelbank)
4. 07:39 AM - Re: Jabiru 3300 cooling and noise (DaveG601XL)
5. 08:25 AM - Re: Re: Jabiru 3300 cooling and noise (Mark Hubelbank)
6. 08:50 AM - Re: Re: Jabiru 3300 cooling and noise (Paul Mulwitz)
7. 09:16 AM - Re: Re: Jabiru 3300 cooling and noise (Mark Hubelbank)
8. 12:13 PM - Gear (BobbyPaulk@comcast.net)
9. 01:34 PM - Re: Gear (Paul Mulwitz)
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| Subject: | Re: Jabiru 3300 cooling and noise |
Mark,
I am also using a #4 round cable for engine grounding. I have an I-com A200 radio,
which is certainly not a high-end model that I doubt has anything for spike
suppression built-in. I have no engine-induced radio noise and have been told
my transmissions are pretty clear. I get a little strobe noise in the system,
but that is about it. Have you tried a new antenna or antenna wire? Antenna
installation and grounding to the aircraft skin itself is quite important
too. Also, have you taken your issue to the AeroElectric forum here in Matronics??
There are some real voltheads over there.
Do you have the early style, flat, automotive oil cooler or the newer Positech
cooler. I have the Positech installed per the Jabiru instructions and have no
real issues with it. Oil temps up to 90F oat are usually below 220F. 202-212F
are more typical for an average summer flying day. I did add some additional
aluminum and RTV around the cooler to ensure as much air as possible goes through
it, but that is about it.
--------
David Gallagher
601 XL/Jabiru 3300
First flight 7/24/08, Upgraded 3/19/10
Flew it to Oshkosh '09 & '10
180+ hours and climbing!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346034#346034
Message 3
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| Subject: | Re: Jabiru 3300 cooling and noise |
David,
I am almost sure the ICOM line all have some form of ANL (automatic
noise limiting) in the design I will see if I can check that out. It is
really very simple. Unfourtunately, the Microair M760 I have clearly
does not. This week, I am going to do some tests with signal processing
to simulate an ANL. If that works, I will probably build one as an add
on. The alternative would be to use a Becker radio and I have heard
mixed reports on the noise rejection of a Becker it may not have ANL
either. If my test works, I will publish the design.
I have proved that all the noise comes in through the antenna lead.
The antenna is on the bottom of the fuselage behind the seats, any
further back and there would be risk of antenna contact during landing.
Still one source of noise is the exhaust pipe which can act as an
antenna. I have not been able to do a test to eliminate that yet. Where
is your antenna?
I have the Positech cooler with oversize hose and it is very well
sealed on the air intake side. There is a lot of air moving through it.
I am wondering if this engine has one of the rubbing piston cylinders
and is generating excess heat. It does not show when turning it over by
hand but when the engine is very hot, perhaps the clearances are too
small. If that is the issue, I don't think it is being changed.
Note that I can also keep oil temps down to under 220F (which is
still above Jabiru recommendations) if I keep the power down to under
6GPH which is well under 75% given the inefficiency of these engines.
When I actually want to go somewhere and use a "high cruse" of 2900-3000
RPM at 4500 to 5500 feet and 7 GPH, the oil temperature climbs sharply.
On 07/12/2011 7:30 AM, DaveG601XL wrote:
> --> Zenith601-List message posted by: "DaveG601XL"<david.m.gallagher@ge.com>
>
> Mark,
>
> I am also using a #4 round cable for engine grounding. I have an I-com A200
radio, which is certainly not a high-end model that I doubt has anything for spike
suppression built-in. I have no engine-induced radio noise and have been
told my transmissions are pretty clear. I get a little strobe noise in the system,
but that is about it. Have you tried a new antenna or antenna wire? Antenna
installation and grounding to the aircraft skin itself is quite important
too. Also, have you taken your issue to the AeroElectric forum here in Matronics??
There are some real voltheads over there.
>
> Do you have the early style, flat, automotive oil cooler or the newer Positech
cooler. I have the Positech installed per the Jabiru instructions and have
no real issues with it. Oil temps up to 90F oat are usually below 220F. 202-212F
are more typical for an average summer flying day. I did add some additional
aluminum and RTV around the cooler to ensure as much air as possible goes
through it, but that is about it.
>
> --------
> David Gallagher
> 601 XL/Jabiru 3300
> First flight 7/24/08, Upgraded 3/19/10
> Flew it to Oshkosh '09& '10
> 180+ hours and climbing!
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=346034#346034
>
>
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 4
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| Subject: | Re: Jabiru 3300 cooling and noise |
Mark,
You are certainly more well versed in radio technology than I am so I will check
out of that discussion and monitor it from aside. My antenna is mounted on
top near the rear of the baggage deck. I have had people ask me if I tuned my
antenna or cable lengths with a SWR meter and all I can do is give a dumb stare
in return. I just hooked them all up and started talking.
Have you tried extending the rear cowl lip to see if the added pressure drop helps??
Since you already know the pressure drop across your cooler, I assume you
are well versed in that trick also. I have the Sensenich wood prop that I
am told is shaped to help with hub airflow.
How about a new oil temp thermocouple? They are "usually" pretty bullet proof
but that would at least eliminate the instrumentation as a source of your problem.
Dropping it in boiling water and watching the Dynon readout would would
serve the same purpose. Hopefully there are no junctions in the thermocouple
wire between the thermocouple and your Dynon.
Just to compare observations, it looks like you cruise around faster than I do.
If I am just tooling around the area, I set ~2650 RPM. Solo, this gets me about
115MPH IAS and the 100LL flows at around 4.5 GPH. If I kick it up to 2850
RPM, it only seems to get me another 10 MPH at 6.5 GPH. I usually keep the
throttle between 2650 and 2750 RPM for cross countries. With my wood prop, I
only see 3000 RPM if I am WOT and in a slight dive.
Good luck,
--------
David Gallagher
601 XL/Jabiru 3300
First flight 7/24/08, Upgraded 3/19/10
Flew it to Oshkosh '09 & '10
180+ hours and climbing!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346059#346059
Message 5
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| Subject: | Re: Jabiru 3300 cooling and noise |
David,
I did the sensor calibration and also did tests with thermocouples
on both sides of the oil cooler. Even though the pressure difference is
well within spec, I may still try the bigger lip just for the summer. If
that helps, then one does ask why.
If my theory that the exhaust system can act as an antenna (leaking
RF from the cylinders). then your top mounted antenna would be better
even if in theory it is not as good for ATC communications. I had a AA-5
with an antenna on the top and one on the bottom and the bottom mounted
one was clearly better for some ATC use, that is why I picked the bottom
location. Still I can think of a way I can do a test to try it without
actually making a hole and mounting an antenna.
On 07/12/2011 10:37 AM, DaveG601XL wrote:
> --> Zenith601-List message posted by: "DaveG601XL"<david.m.gallagher@ge.com>
>
> Mark,
>
> You are certainly more well versed in radio technology than I am so I will check
out of that discussion and monitor it from aside. My antenna is mounted on
top near the rear of the baggage deck. I have had people ask me if I tuned
my antenna or cable lengths with a SWR meter and all I can do is give a dumb stare
in return. I just hooked them all up and started talking.
>
> Have you tried extending the rear cowl lip to see if the added pressure drop
helps?? Since you already know the pressure drop across your cooler, I assume
you are well versed in that trick also. I have the Sensenich wood prop that
I am told is shaped to help with hub airflow.
>
> How about a new oil temp thermocouple? They are "usually" pretty bullet proof
but that would at least eliminate the instrumentation as a source of your problem.
Dropping it in boiling water and watching the Dynon readout would would
serve the same purpose. Hopefully there are no junctions in the thermocouple
wire between the thermocouple and your Dynon.
>
> Just to compare observations, it looks like you cruise around faster than I do.
If I am just tooling around the area, I set ~2650 RPM. Solo, this gets me
about 115MPH IAS and the 100LL flows at around 4.5 GPH. If I kick it up to 2850
RPM, it only seems to get me another 10 MPH at 6.5 GPH. I usually keep the
throttle between 2650 and 2750 RPM for cross countries. With my wood prop,
I only see 3000 RPM if I am WOT and in a slight dive.
>
> Good luck,
>
> --------
> David Gallagher
> 601 XL/Jabiru 3300
> First flight 7/24/08, Upgraded 3/19/10
> Flew it to Oshkosh '09& '10
> 180+ hours and climbing!
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=346059#346059
>
>
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 6
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| Subject: | Re: Jabiru 3300 cooling and noise |
Mark,
If you think RF from the engine is being radiated from the exhaust
system then the way to fix this is to improve the grounding of the
engine. If the engine is well grounded it cannot radiate any signals.
Paul
On 7/12/2011 8:22 AM, Mark Hubelbank wrote:
> David,
> I did the sensor calibration and also did tests with thermocouples
> on both sides of the oil cooler. Even though the pressure difference
> is well within spec, I may still try the bigger lip just for the
> summer. If that helps, then one does ask why.
>
> If my theory that the exhaust system can act as an antenna
> (leaking RF from the cylinders). then your top mounted antenna would
> be better even if in theory it is not as good for ATC communications.
> I had a AA-5 with an antenna on the top and one on the bottom and the
> bottom mounted one was clearly better for some ATC use, that is why I
> picked the bottom location. Still I can think of a way I can do a test
> to try it without actually making a hole and mounting an antenna.
Message 7
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| Subject: | Re: Jabiru 3300 cooling and noise |
Paul,
Unfourtunately that is not completely true. The length of the
exhaust pipe from the muffler is almost an ideal 1/4 wavelength antenna
at aircraft VHF frequencies. Even if everything is perfectly grounded,
if some RF energy is coupled from the cylinders or adjacent spark plug
wires into the exhaust system, it will do an excellent job of radiating.
Some tests will tell, not easy but it can be done. If this is really
happening, it might explain why some people have success with resistor
plugs. We might note that most production aircraft spark plugs are
resistor designs even with shielded wires. This is all theory.
On 07/12/2011 11:46 AM, Paul Mulwitz wrote:
>
> Mark,
>
> If you think RF from the engine is being radiated from the exhaust
> system then the way to fix this is to improve the grounding of the
> engine. If the engine is well grounded it cannot radiate any signals.
>
> Paul
>
> On 7/12/2011 8:22 AM, Mark Hubelbank wrote:
>> David,
>> I did the sensor calibration and also did tests with
>> thermocouples on both sides of the oil cooler. Even though the
>> pressure difference is well within spec, I may still try the bigger
>> lip just for the summer. If that helps, then one does ask why.
>>
>> If my theory that the exhaust system can act as an antenna
>> (leaking RF from the cylinders). then your top mounted antenna would
>> be better even if in theory it is not as good for ATC communications.
>> I had a AA-5 with an antenna on the top and one on the bottom and the
>> bottom mounted one was clearly better for some ATC use, that is why I
>> picked the bottom location. Still I can think of a way I can do a
>> test to try it without actually making a hole and mounting an antenna.
>
>
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 8
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Paul,
My gear was installed with the flat side to the rear at first. ( old man's disease
) Anyway I moved the wheels forward roughly 6" by turning it around. I weigh
185 lbs. all up flying weight and the nose does not come up when I enter the
plane. My drawings say to install it flat side forward but the picture in my
kit shows it aft.
I am glad i changed it.
Bobby
3300 Jabiru
601 "B"
120 hrs.
Do Not Archive
Message 9
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Hi Bobby,
Thanks for the message. That is the way I installed my gear to begin with.
I think this is all just proof that each model airplane flies a bit
differently from all the rest. The Tecnam I was flying had the main
gear very close to the CG, and that allowed rotation early on takeoff
and holding off the nose on landing until the plane was just about stopped.
The Zodiac XL is more nose heavy on the main gear. I think this means
you need to get it going faster on the runway before lifting the nose.
Perhaps you can take off at the same pitch attitude as you get rolling
on all three wheels. So, it takes more runway to take off. This is not
a big deal since even twice as much runway means about 600 feet instead
of 300. I don't think there is any public airport that would be too
short for a Zodiac and it was never meant as a bush plane.
Paul
On 7/12/2011 12:09 PM, BobbyPaulk@comcast.net wrote:
> Paul,
> My gear was installed with the flat side to the rear at first. ( old
> man's disease ) Anyway I moved the wheels forward roughly 6" by
> turning it around. I weigh 185 lbs. all up flying weight and the nose
> does not come up when I enter the plane. My drawings say to install it
> flat side forward but the picture in my kit shows it aft.
> I am glad i changed it.
>
> Bobby
> 3300 Jabiru
> 601 "B"
> 120 hrs.
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