Today's Message Index:
----------------------
1. 04:11 AM - Re: Re: IVO Prop Motor Current Limiter and Electron ic CB (n801bh@netzero.com)
2. 07:15 AM - Re: IVO Prop System Brushes (Robert L. Nuckolls, III)
3. 10:26 AM - Alternator cooling (jonlaury)
4. 11:53 AM - Shunt/Hall Sensor placement (jonlaury)
5. 11:59 AM - Re: Alternator cooling (Robert L. Nuckolls, III)
6. 12:10 PM - Re: Re: IVO Prop Motor Current Limiter and Electron ic CB (RGent1224@aol.com)
7. 12:11 PM - Re: Re: IVO Prop Motor Current Limiter and Electronic CB (Glaeser, Dennis)
8. 12:51 PM - Re: Shunt/Hall Sensor placement (jonlaury)
9. 03:27 PM - Re: Infinity grip (Eric M. Jones)
10. 10:17 PM - Re: Re: Shunt/Hall Sensor placement (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: re: IVO Prop Motor Current Limiter and Electron |
ic CB
To clarify things.....
Bob, it is the brushes that transfer the power to the prop motor on the
hub,,, not the actual pitch change motor itself. When the first motor f
ailed I did discuss this with Ron @ Ivo and he was insistant not for me
to open the motor and do an autopsy on it but to just send it back. Whic
h I did and he promply replaced it back then. I don't know if it tricky
to open up, or there is some propritary stuff in it he doesn't was peopl
e to see or what.
do not archive.
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: AeroElectric-List: re: IVO Prop Motor Current Limiter and Elect
ronic CB
olls.bob@aeroelectric.com>
At 09:05 PM 5/10/2010, you wrote:
st.net>
>
>I may be mistaken, but I thought the Ivo prop had brushes that were
>rubbing all the time the prop was turning -- I.e. they transfer
>power from the stationary part of the engine to the rotating prop,
>which has the motor mounted on it, (which then rotates with the prop).
Good questions. No doubt there are two sets of brushes.
One that conducts power from the stationary airframe and
rotating pitch motor assembly, a second set of brushes
run on the commutator within the permanent magnet motor.
So I need to expand my own question to ask which of
the two brush sets is demonstrating a service-life
issue.
Bob . . .
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Message 2
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| Subject: | Re: IVO Prop System Brushes |
At 04:20 AM 5/11/2010, you wrote:
To clarify things.....
Bob, it is the brushes that transfer the power to the prop motor on
the hub,,, not the actual pitch change motor itself.
THAT is a very difficult set of components to optimize to
design goals. Brushes on alternators run on the smallest possible
diameters and smooth surfaces. Smoothness reduces wear, diameter
controls surface speed under the brushes. Brushes in tiny
motors benefit most from their tiny commutators . . . in spite
of having to run over a segmented surface.
Brushes that carry power to a moving prop hub DO benefit from
smooth surfaces . . . but they run 100% of the time, are exposed
to environmental contaminants, and have high surface speeds. A
de-ice slip ring for a three bladed prop . . .
Emacs!
can be about 10" in diameter and has three slip rings.
Brushes are a high-maintenance item on these systems
too.
When the first motor failed I did discuss this with Ron @ Ivo and he
was insistent not for me to open the motor and do an autopsy on it
but to just send it back. Which I did and he promptly replaced it
back then. I don't know if it tricky to open up, or there is some
proprietary stuff in it he doesn't was people to see or what.
Probably nothing sinister here. The clues that lead to
good failure diagnosis can be subtle . . . they can also
be fragile to the extent that they are destroyed or
missed by someone opening up a device under study
for the first time.
I don't think I've ever encountered a situation where
a supplier was attempting to keep his "dirty laundry"
a secret. I've encountered many instances were well
meaning but unskilled investigators trashed or missed
an important data point during a teardown inspection.
Bob . . .
Message 3
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| Subject: | Alternator cooling |
After scouring the archives and only one post on topic, I come to you all with
an Alternator cooling question.
My alternators are driven off a spur gear and hence turn opposite to their intended
direction. I've built fiberglass "caps" with blast tubes over the diode plate
end of the alternators to try to keep them cool, but they haven't been run
yet to see if the cooling is adequate.
Has anyone else dealt with this?
Thanks,
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=297365#297365
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| Subject: | Shunt/Hall Sensor placement |
In Z-13, I would like to place a Hall Sensor for the AUX Alternator between the
battery contactor and the Batt Bus to locate it in the cabin and within it's
recommended ambient temperature operating envelope.
Ditto for the Primary Alternator between the Batt Contactor and the Main Bus.
Any caveats here?
If only one alternator will be online at a time, is there any reason why I should
not run the alternator outputs through just one Hall Sensor?
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=297368#297368
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| Subject: | Re: Alternator cooling |
At 12:23 PM 5/11/2010, you wrote:
>
>After scouring the archives and only one post on topic, I come to
>you all with an Alternator cooling question.
>
>My alternators are driven off a spur gear and hence turn opposite to
>their intended direction. I've built fiberglass "caps" with blast
>tubes over the diode plate end of the alternators to try to keep
>them cool, but they haven't been run yet to see if the cooling is adequate.
>
>Has anyone else dealt with this?
. . . and if they had, their stories are probably
of limited or no value.
Cooling studies are always accomplished on an installation-
by-installation, model-by-model basis. Then the cooling
studies are blessed as 'golden' because type certificated
aircraft are configuration managed . . . you don't change
ANYTHING without due consideration for unintended consequences.
The ONLY way to ascertain your particular alternator cooling
requirements are to do max angle of climb, full electrical
load cooling studies with thermocouples attached to the
alternator's expected hot spots. After the test data is gathered
and averaged (over 5 or more climb profiles) you then correct the
measured temperatures for hot-day climate conditions.
Failures of alternators on OBAM aircraft due to inadequate
cooling are rare. Major contributors to this rarity are
light loading of alternators, minimum durations for heavy
loads, plenty of air-flow in vicinity of alternator, and
to some degree, luck.
You've obviously 'worried' about it enough to craft
specifically tailored cooling components . . . but
are still unsure. I suspect it's because nobody has repeated
your experiment before and there's no data to share.
So if you're really compelled to know, then you'll
need to fit thermocouples to your alternators bearing
mounts, diode heat sink, and perhaps a couple places
in the stator windings. You'll also need to fit your
airplane with a load bank you can adjust to set up
a nameplate rated load on the alternator along with
instrumentation to read alternator voltage, current,
and thermocouple temperatures. Then you get somebody
to fly with you to do the flight tests.
Once this data is acquired, then YOU will have become
the expert for whether or not your worries were justified
and extra ordinary cooling measures were necessary and
useful.
Bob . . .
>Thanks,
>John
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=297365#297365
>
>
>Checked by AVG - www.avg.com
>05/11/10 01:26:00
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 6
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| Subject: | Re: re: IVO Prop Motor Current Limiter and Electron |
ic CB
How is the tracking of those brushes??
I remember from way back when working on the Curtis Electric prop it was a
major problem for the prop specialists to get it right. I would check and
recheck them as part of the preflight to make sure they were tracking true
and at say a twenty five hour check them with something like Prussian Blue
or whatever Ron recommends for checking the tracking the brushes. If
Prussian Blue doesn't ring a bell for you, it was what was used 60 years ago when
I was working on them
Know you know my age
Dick
In a message dated 5/11/2010 6:16:58 A.M. Central Daylight Time,
n801bh@netzero.com writes:
To clarify things.....
Bob, it is the brushes that transfer the power to the prop motor on the
hub,,, not the actual pitch change motor itself. When the first motor failed
I did discuss this with _Ron @ Ivo_ (mailto:Ron@Ivo) and he was insistant
not for me to open the motor and do an autopsy on it but to just send it
back. Which I did and he promply replaced it back then. I don't know if it
tricky to open up, or there is some propritary stuff in it he doesn't was
people to see or what.
do not archive.
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: AeroElectric-List: re: IVO Prop Motor Current Limiter and
Electronic CB
<nuckolls.bob@aeroelectric.com>
At 09:05 PM 5/10/2010, you wrote:
<wschertz@comcast.net>
>
>I may be mistaken, but I thought the Ivo prop had brushes that were
>rubbing all the time the prop was turning -- I.e. they transfer
>power from the stationary part of the engine to the rotating prop,
>which has the motor mounted on it, (which then rotates with the prop).
Good questions. No doubt there are two sets of brushes.
One that conducts power from the stationary airframe and
rotating pitch motor assembly, a second set of brushes
run on the commutator within the permanent magnet motor.
So I need to expand my own question to ask which of
the two brush sets is demonstrating a service-life
issue.
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Message 7
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| Subject: | Re: re: IVO Prop Motor Current Limiter and Electronic |
CB
I will validate that it is the prop brushes, not the motor brushes that are the
limited wear items.
For those who haven't seen the IVO, the contact rings behind the prop are just
aluminum disks. The brushes are a metallic material impregnated with carbon/graphite.
The aluminum contact surface becomes coated with the carbon/graphite
material, which improves the wear characteristics with time.
The motor assembly has a planetary gear train which drives a jack screw. A collar
on the jack screw engages pins on an arm attached to the torque tubes in the
prop. The prop is a composite material that flexes as the torque tube is twisted,
providing the pitch adjustment.
IMO, the gear train is the most vulnerable part of the system, primarily because
the 'pitch stops' are rubber washers that cushion the collar as it jams against
the end plates! The motor doesn't see nearly the mechanical strain that the
gears do (I can't speak to the electrical strain of being mechanically stopped).
A 'motor' failure may well be a gear train failure, not a failure of the
electric motor itself. I also experienced such a failure, due to an installation
interference. I did not disassemble the unit, but I did 'loosen' things
to try to peek inside. It is a very tight assembly, so I didn't see much. I
did see the motor brushes, and they, and the commutator, showed no signs of distress.
I wouldn't be surprised that special jigging/tooling is required for
assembly, which would explain Ron's position.
This is why I like the idea of the electronic limiting feature of Bob's circuit.
The reed switch is a huge improvement over guessing where the prop is set,
or using the provided CB as the ultimate 'stop'. It lets the user know when the
limit is reached, but doesn't prevent abuse (intentional or inadvertent).
The electronic CB prevents the abuse, and can only help improve the life of the
gear train and electric motor.
The prop brushes will still wear as usual :-)
Dennis Glaeser
------------------------------------------------------------------------
From: n801bh@netzero.com
To clarify things.....
Bob, it is the brushes that transfer the power to the prop motor on the
hub,,, not the actual pitch change motor itself. When the first motor f
ailed I did discuss this with Ron @ Ivo and he was insistent not for me
to open the motor and do an autopsy on it but to just send it back. Which
h I did and he promptly replaced it back then. I don't know if it tricky
to open up, or there is some proprietary stuff in it he doesn't was people to see
or what.
do not archive.
Ben Haas
N801BH
www.haaspowerair.com
Message 8
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| Subject: | Re: Shunt/Hall Sensor placement |
After looking long enough at my proposed HS placement, I can see that one of the
shortcomings is that in the intended location, the sensors would only show alt
throughput to the bus. In the case of the main bus, I could see alt output
to the bus if the main contactor was open. But if it's closed, I'd have no way
of knowing for sure if the alt was functioning at all because battery current
throughput could be masking a dead alternator.
On the batt bus there would be no way to know if the Aux alt was contributing or
not.
RETHINK time.
Sorry for the bother.
J
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=297377#297377
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| Subject: | Re: Infinity grip |
Just a note: I saw a stick grip used for custom cars that had four buttons in the
gear shift knob (and probably a battery) that were RF connected to a remote
little switch box. (This might have controlled relays). The idea was to turn
on/off NOX or lights or whatever. Cars usually don't have hollow stick shifters,
so this is an advantage.
I can imagine this might find some use in somebody's aircraft, especially ultralights.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=297416#297416
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| Subject: | Re: Shunt/Hall Sensor placement |
At 02:48 PM 5/11/2010, you wrote:
After looking long enough at my proposed HS placement, I can see that
one of the shortcomings is that in the intended location, the sensors
would only show alt throughput to the bus. In the case of the main
bus, I could see alt output to the bus if the main contactor was
open. But if it's closed, I'd have no way of knowing for sure if the
alt was functioning at all because battery current throughput could
be masking a dead alternator.
Check the chapter on batteries in the 'Connection
again . . .
Batteries deliver energy at 12.7 volts and BELOW
while alternators deliver energy at 13.8 volts
and ABOVE.
If an alternator is working, it will have a
positive indication of output current consisting
of aircraft system loads PLUS anything the battery
is asking for in order to replenish a discharge.
Alternators mask dead batteries . . . but batteries
don't mask anything.
Further if the alternator is working, then the bus
voltage is high enough to keep low voltage warning
lights out which are calibrated at 13.0 volts.
On the batt bus there would be no way to know if the Aux alt was
contributing or not.
Same principals apply for both alternators.
Bob . . .
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