Today's Message Index:
----------------------
1. 06:34 AM - Re: Antenna Question (Brian Lloyd)
2. 06:41 AM - Re: DC Power Master Switch (Bobby Hester)
3. 08:50 AM - Brian LLoyd - airstarts (Fergus Kyle)
4. 09:54 AM - Re: Architecture for 2 batteries and 1 alternator (Robert L. Nuckolls, III)
5. 10:07 AM - Re: DC Power Master Switch (Robert L. Nuckolls, III)
6. 10:12 AM - Re: Antenna Question (Robert L. Nuckolls, III)
7. 10:13 AM - Re: Antenna Question (Robert L. Nuckolls, III)
8. 11:43 AM - Starter EMF ()
9. 01:59 PM - Re: Garmin series 400 installation manual ? (Thesee Gilles)
10. 02:08 PM - bob nuckolls is on a roll (RV8ter@aol.com)
11. 02:15 PM - Re: Garmin series 400 installation manual ? (Harley)
12. 04:26 PM - Re: bob nuckolls is on a roll (Robert L. Nuckolls, III)
13. 04:34 PM - Re: incident with fuse holder (Robert L. Nuckolls, III)
14. 07:42 PM - OV protection for PM alternators (Ken)
15. 07:43 PM - Re: Architecture for 2 batteries and 1 alternator (glaesers)
16. 09:46 PM - Re: Starter EMF (Robert L. Nuckolls, III)
17. 10:17 PM - Antenna Placement. (Dean Psiropoulos)
Message 1
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| Subject: | Re: Antenna Question |
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
On Aug 21, 2004, at 8:47 PM, Richard E. Tasker wrote:
> --> AeroElectric-List message posted by: "Richard E. Tasker"
> <retasker@optonline.net>
>
> The short answer: If you want the best performance you must connect it
> to the end. The 40" was chosen with the frequency of the marker beacon
> in mind, so connecting the coax somewhere in the middle will not work
> well at all. On the other hand, the 1/2" wide aluminum will resonate
> at
> a lower frequency than a thin wire, so you could get away with a
> shorter
> length (connected at the end). I do not remember what the equations
> are
> for calculating this so maybe someone else can chime in here...
I am too lazy to go look it up now but it is only a few percent,
nothing like the 50% you need.
OTOH, one of the best ways to find anything out is to try it. Lash up
your short antenna and go fly over a marker beacon transmitter and see
how it works. You may find it is just fine. It doesn't take much
antenna to be able to hear a several watt transmitter 2000
line-of-sight feet away.
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
+1.340.998.9447 St. Thomas, VI 00802
Message 2
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| Subject: | Re: DC Power Master Switch |
--> AeroElectric-List message posted by: Bobby Hester <bhester@hopkinsville.net>
PeterHunt1@aol.com wrote:
>--> AeroElectric-List message posted by: PeterHunt1@aol.com
>
>Bob/Others
>
>I am confused and need help. In Figure Z-13 (utilizing SD-8 alternator) the
>DC power master switch is a 2-10. In Figure Z-12 (utilizing SD-20 alternator)
>the DC power master switch is a 2-3. Why the difference? Is it that with
>the 2-10 switch the engine is to be started with this switch in the center
>position? Is it that with the 2-10 switch the regulator can be disconnected from
>the bus for some reason, perhaps testing?
>
>The reason I am asking is I initially planned to install the SD-8 alternator
>and wired my panel accordingly (Figure Z-13) with the 2-10 master power
>switch. I have since decided to install the SD-20 which takes me to Figure Z-12
>which calls for a 2-3 master power switch. Is it important that I change out
my
>2-10 master power switch with a 2-3 switch? If not, what is the purpose for
>the center position on the 2-10 switch?
>
>A little help would be appreciated. Thanks.
>
>Pete Hunt
>Clearwater, FL
>RV-6, Wiring
>
>
I not sure if this will help you but, I do know that with a 2-10 switch
the center is for the battery and the top for the alternator.
--
Surfing the Web from Hopkinsville, KY
Visit my web site at: http://www.geocities.com/hester-hoptown/RVSite/
RV7A Slowbuild wings-QB Fuse :-)
Message 3
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| Subject: | Brian LLoyd - airstarts |
--> AeroElectric-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
Brian,
Interested to see the WW II methods of Red squadrons is
perpetuated in the Yaks etc. I read of these procedures in sum-ups of Russki
methods in the forties and forgot all about 'em. I wondered how you became
so acquainted until of course I saw you had a sample.
The method was superb for operating a fighter squadron in a
snowy farmer's field in winter with one truck, which made compressed air,
kept the gathered oil warm, housed the overnight batteries AND provided
warmth for sleeping both pilots and crew.
How that would echo in NA was a mystery to me. The advantage was
airborne weight I am told, but what is the weight cost of the air turbine
starter (?) and the compressed air tank and piping? .....and hoiw would it
compare to present fuel system starters?
Cheers, Ferg
Europa A064
Message 4
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| Subject: | Re: Architecture for 2 batteries and 1 alternator |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
> >> My question is:
> >> what kind of failure could occur which would NOT trigger the LV
> >> warning, but
> >> could drain the batteries?
> >
> > None
>
>There is always failure of the LV warning itself.
But it's pre and in-flight testable. The LV warning light is
the first thing to come to life when you turn on the battery
master. Due notice of the LV warning light activity should
be a part of a pre-flight checklist. The ONLY time a LV warning
light gets exercised, is when the alternator is off or failed . . .
which is a very low percentage of total operating time . . . i.e.,
the warning light system is very low operating stress and most
use LEDs so they have very long projected service life. Last,
for LV warning failure to participate in a tense situation
while airborne requires a DOUBLE failure . . . that of the LV
warning light followed by failure of the alternator.
All things considered, the lowly LV warning light offers a
very robust, active notification of alternator failure that's
about as reliable as any architecture I can think of.
Bob . . .
---
Message 5
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| Subject: | Re: DC Power Master Switch |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
At 08:46 AM 8/22/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: Bobby Hester
><bhester@hopkinsville.net>
>
>PeterHunt1@aol.com wrote:
>
> >--> AeroElectric-List message posted by: PeterHunt1@aol.com
> >
> >Bob/Others
> >
> >I am confused and need help. In Figure Z-13 (utilizing SD-8 alternator)
> the
> >DC power master switch is a 2-10. In Figure Z-12 (utilizing SD-20
> alternator)
> >the DC power master switch is a 2-3. Why the difference? Is it that with
> >the 2-10 switch the engine is to be started with this switch in the center
> >position? Is it that with the 2-10 switch the regulator can be
> disconnected from
> >the bus for some reason, perhaps testing?
> >
> >The reason I am asking is I initially planned to install the SD-8
> alternator
> >and wired my panel accordingly (Figure Z-13) with the 2-10 master power
> >switch. I have since decided to install the SD-20 which takes me to
> Figure Z-12
> >which calls for a 2-3 master power switch. Is it important that I
> change out my
> >2-10 master power switch with a 2-3 switch? If not, what is the purpose
> for
> >the center position on the 2-10 switch?
> >
> >A little help would be appreciated. Thanks.
> >
> >Pete Hunt
> >Clearwater, FL
> >RV-6, Wiring
> >
> >
>I not sure if this will help you but, I do know that with a 2-10 switch
>the center is for the battery and the top for the alternator.
Close but it's a little more complicated than that. Alternators generally
do not run well without also having a battery on line. Early electrified
aircraft used generators which would come on line and deliver useful,
relatively
clean energy without a battery. When generators were removed from
certified ships
and replaced with alternators, powers-that-be deduced a need to make
sure that
an alternator could not be left on-line without the battery . . . and that
the battery was on-line before the alternator was brought up.
This design philosophy gave birth to the infamous "split rocker" master
switch that has been part-and-parcel of the majority of single engine
aircraft
architectures for nearly 40 years. I've seen many OBAM aircraft where the
builder wanted to use some whippy looking switches on the panel but had
a Cesssna style split rocker switch enshrined in a place of honor.
The 2-10, progressive transfer switch can provide the same action without
having to resort to the over-priced split rocker. The 2-10 looks like its
brothers and cousins and mounts in the same nice round hole.
Full down turns both battery -AND- alternator OFF. Mid position turns only
the battery ON. Upper position leaves the battery ON and turns the
alternator
ON too. If one doesn't want to spend the dollars and take the time to
label a three-position, progressive transfer 2-10 switch, the 2-3 is a
completely acceptable substitute. In this case, battery and alternator
are brought on and off together . . . an entirely satisfactory mode
of operation also. When one uses a pullable breaker for the crowbar
OV protection, there's a panel mounted control that permits an alternator
to be taken off line for battery only ground operations (usually for
maintenance) -OR- to take the alternator off line should it become unstable
in flight. If it were my airplane, I'd probably use a 2-3 switch. It's
inexpensive and spares can be acquired from lots of sources.
Bob . . .
---
Message 6
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| Subject: | Re: Antenna Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
At 09:33 AM 8/22/2004 -0400, you wrote:
>--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
>
>
>On Aug 21, 2004, at 8:47 PM, Richard E. Tasker wrote:
>
> > --> AeroElectric-List message posted by: "Richard E. Tasker"
> > <retasker@optonline.net>
> >
> > The short answer: If you want the best performance you must connect it
> > to the end. The 40" was chosen with the frequency of the marker beacon
> > in mind, so connecting the coax somewhere in the middle will not work
> > well at all. On the other hand, the 1/2" wide aluminum will resonate
> > at
> > a lower frequency than a thin wire, so you could get away with a
> > shorter
> > length (connected at the end). I do not remember what the equations
> > are
> > for calculating this so maybe someone else can chime in here...
>I am too lazy to go look it up now but it is only a few percent,
>nothing like the 50% you need.
Right . ..
>OTOH, one of the best ways to find anything out is to try it. Lash up
>your short antenna and go fly over a marker beacon transmitter and see
>how it works. You may find it is just fine. It doesn't take much
>antenna to be able to hear a several watt transmitter 2000
>line-of-sight feet away.
Exactly. A receiver with a wet noodle for an antenna would
hear a marker beacon transmitter during a typical approach. The
need for high sensitivity marker beacon performance went away
with the AN Range stations and what was called "airway markers"
back in the good ol' days.
In the final analysis, the repeatable experiment rules. Why
not start with 40' of wire and then make progressive tests
with progressive cuts of, say 2" each time. It would be interesting
to note just how LITTLE your antenna can be and still get the
lights to illuminate at some constant height over a selected
transmitter.
Write up your experiment with details on the setup and procedure
and post on the List for everyone to know and if possible, try
for themselves to confirm, deny or refine the data . . .
Bob . . .
---
Message 7
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| Subject: | Re: Antenna Question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
At 05:28 PM 8/21/2004 -0500, you wrote:
>--> AeroElectric-List message posted by: "Charles E. Brame"
><charleyb@earthlink.net>
>
>I am installing a Marker Beacon antenna in my right wing tip using
>shielded single conductor cable as the antenna lead. I considered
>Electric Bob's suggestion of just exposing the last 40 inches of the
>lead, but I was about 20 inches short of antenna cable. So I pro-sealed
>a 1/2 inch wide, 40 inch strip of .016 aluminum to the bottom of the
>fiberglass wing tip as the antenna.
>
>Question: Does the antenna lead have to connect to the end of the
>aluminum strip or can it be connected anywhere along its length? (It
>would be most convenient to connect the lead about 15 inches from one
>end, if such an installation will work.)
On the end . . .
Bob . . .
---
Message 8
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--> AeroElectric-List message posted by: <bakerocb@cox.net>
Message Previously Posted by Brian Lloyd
<< > Close . . . but it's not "field collapse" that we're shorting
> out but counter EMF of the motor which is acting like a generator
> during the motor's spin down interval.
I had a really weird starting problem on my Comanche for a number of
years that turned out to be related to this. The problem started when
we replaced the engine and the new engine came equipped with a
retard-breaker magneto (shower of sparks). It seemed to me that the
engine was always harder to start now. We ended up replacing batteries
and starters in an attempt to remedy the problem to no avail.
Then I noticed one day that the engine didn't really start until
shortly AFTER I released the starter button. I found that I could get
relatively good starts by very short cranking intervals. Paying extra
close attention I noticed that, not only did it start after I released
the button is was like 1/2 second after releasing the start button that
it really started. Everything in the shower of sparks system tested
properly as did both running and starting ignition timing.
I then traced down the wiring and found that whoever had wired the
shower of sparks system had wired the retard relay to the starter side
of the starter solenoid. When the engine fired and kicked the Bendix
out, the starter spun up to a high speed. When I released the start
button the back EMF from the starter held the retard relay in keeping
left mag retarded and the right mag off until the starter spun down.
Of course it didn't run right. I then moved the power for the retard
relay from the output of the starter solenoid to the coil of the
starter solenoid (solenoid pulled in by application of 12V) and the
problem was solved. I tried to explain the problem and solution to the
A&P and IA who had been working on the airplane and they just looked at
me like I was speaking Swahili. Brian Lloyd >>
8/22/2004
Hello Brian, I think that you may have identified a similar problem for me many
thanks in advance if we can confirm this.
Here is the situation: I have built and am flying a KIS TR-1 amateur built experimental
airplane with a TCM IO-240 B9B engine in it. It has a B&C starter that
uses an on-starter solenoid to both complete the electrical circuit to the starter
motor and engage a pinion gear. Electricity gets to the starter via a conventional
starter contactor which is activated by a push button on the instrument
panel that sends 12 volts to the coil of the starter contactor. On the starter
output side of the starter contactor I have a single electrical connection
going to a 5 amp fuse then splitting to go to both a starter engaged light
on the instrument panel and to the voltage input pin of a Unison solid state
SlickSTART starting vibrator.
During cranking the retard breaker points of the left magneto feed rapid high voltage
pulses from the starting vibrator to the four upper sparkplugs slightly
after piston top dead center. Also during cranking the normal 26 degrees before
top dead center points of the left and right magneto are grounded out by internal
functioning of the starting vibrator and my right magneto switch on the
instrument panel which is off during cranking.
My engine does not start cleanly it seems to stumble around for awhile after it
initially fires and I have taken my finger off the starting switch. Based on
your experience above I now suspect that the starting vibrator may continue to
keep only the top four plugs firing at slightly after top dead center even after
my finger is off the start switch for some period of time because the starting
vibrator is getting some counter EMF input current from the starter motor
as it winds down. Once that input current dies down the engine runs normally
because the left magneto upper plugs start to fire at 26 degrees before top dead
center and, if I have switched the right magneto on by that time, the lower
plugs also will be firing at that point.
I am now contemplating rewiring in order to feed the starting vibrator from the
starting contactor coil input terminal via a 5 amp fuse and leave the starter
engaged light connected to the starter contactor output terminal via its own
fuse.
What is your assessment of the situation? Thanks again for all that you contribute
to this list I have learned a tremendous amount from your inputs.
OC
PS: The written instructions from Unison do call for the input to the SlickSTART
to come from the output side of the starter contactor. As a side note I had
a very difficult time wiring the SlickSTART into my plane. All of the written
guidance from Unison was couched in cook book terms of how to replace an existing
starting vibrator on a type certificated aircraft with theirs. Reverse engineering
from a known system was the only way to figure out how 3 of the 5 pins
(other than voltage in and ground) were supposed to be connected. Initial queries
to Unison yielded a marketing answer that was completely wrong and led to
miswiring. Fortunately through some personal trouble shooting and persistent
contacts with Unison technical types I was eventually able to break the code.
Message 9
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| Subject: | Re: Garmin series 400 installation manual ? |
--> AeroElectric-List message posted by: Thesee Gilles <Gilles.Thesee@ac-grenoble.fr>
---- Messages dorigine ----
De: Tailgummer@aol.com
Objet: Re: AeroElectric-List: Garmin series 400 installation manual ?
> --> AeroElectric-List message posted by: Tailgummer@aol.com
>
> I tried to send them to your e-mail address but it was returned.
> let me know
> off list if I can help you.
>
>
> John D'Onofrio
>
Dear John,
Thanks for your help. Unfortunately my mail server doesn't handle
large attachments. For the moment I'm stuck, except if one can put the
files on a web server where I could download them.
Thanks again,
Gilles
Message 10
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| Subject: | bob nuckolls is on a roll |
--> AeroElectric-List message posted by: RV8ter@aol.com
dude, you've been on a pretty good clip lately with the good goods! Did you
discover Starbucks triple shots or something :-)
I like the radio shack piece myself. Thanks a lot for looking into that but
please don't burn out...we need you now AND in the future. ;-)
lucky
do not archive
Message 11
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| Subject: | Re: Garmin series 400 installation manual ? |
--> AeroElectric-List message posted by: Harley <harley@agelesswings.com>
If you can send me the file, John, I can put it on my website for Gilles
and he can download it from there when he gets a chance.
Harley Dixon
www.agelesswings.com
Thesee Gilles wrote:
>Objet: Re: AeroElectric-List: Garmin series 400 installation manual ?
>
>
>
>>--> AeroElectric-List message posted by: Tailgummer@aol.com
>>
>>I tried to send them to your e-mail address but it was returned.
>>let me know
>>off list if I can help you.
>>
>>
>>John D'Onofrio
>>
>>
>>
>
>Dear John,
>
>Thanks for your help. Unfortunately my mail server doesn't handle
>large attachments. For the moment I'm stuck, except if one can put the
>files on a web server where I could download them.
>
>Thanks again,
>Gilles
>
Message 12
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| Subject: | Re: bob nuckolls is on a roll |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
At 05:08 PM 8/22/2004 -0400, you wrote:
>--> AeroElectric-List message posted by: RV8ter@aol.com
>
>dude, you've been on a pretty good clip lately with the good goods! Did you
>discover Starbucks triple shots or something :-)
Naw . . . opportunity, enthusiasm and inspiration come in waves not unlike
what is popularly called biorhythms. On days when your ying, yang and
the dew point are all in phase with each other, amazing things may
pour forth . . . but like biorythms, don't look for it to happen every
other week.
>I like the radio shack piece myself. Thanks a lot for looking into that but
>please don't burn out...we need you now AND in the future. ;-)
Thank you for the kind words and thoughts of concern . . . but not
to worry. In my other life, things like that are my job. Tomorrow
morning I'm going to try to convince management types at RAC that
we need to disassemble some outside supplied products and evaluate
exactly how they fail to work in our airplanes. There's a move afoot
to simply trash the existing product and go searching for a new one.
Been there, done that . . . and while we made things better, we didn't
fix the problem 100% . . . because we didn't understand what the REAL
problem was.
We'll see how it goes. It can be a tough sell. After all . . . our
core competency is hanging power plants and systems on piles of
aluminum that we fabricate. My task will be to convince powers-that-
be that just because we don't BUILD a particular item doesn't
mean we shouldn't UNDERSTAND it intimately.
Bob . . .
---
Message 13
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| Subject: | Re: incident with fuse holder |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
At 08:03 PM 8/22/2004 +0200, you wrote:
>Hello Bob,
>
>I had an incident with one of the fuuseholders bought from B&C. The landing
>light 10 A fuse did not go off, but the landing light was no longer working,
>The fuse had melted on the side where the cable of the landing light is
>coming from the switch.
>
>I would like to send you some pictures of the fuse, just tell me to what
>email address.
>
>It looks like part of the fuseholder was also melted (black spots on teh
>fuse, would you recommend to replace the whole holder?
Yes. I've been aware of one other incident like this. In the other case,
the grip tension of the fuse clip was getting damaged by occasional
contact with passenger's foot while ingressing/egressing the airplane.
Your situation may be different but I think the potential root cause
is still the same.
>I'm also wondering what caused this incident, I had originaly a Philips 100W
>landing light in there but as the bulb was only good for 25h I did replace
>it with a motorbike light with a replaceable halogen bulb (however just 55W
>currently).
>
>I do send this to you directly instead of the list as I do not know if it
>makes sense.
Sure . . . it makes sense. Call Todd at B&C tommorow and ask him
for a new fuse holder. Tell him you and I have discussed this and
that he can charge the new holder to me. I'd like for you to send me
the old holder and fuse as intact as possible for the condition they
were in right after the failure.
I'll post this to the List so folks are aware of what's going on.
>Thanks for your help
My pleasure sir.
Bob . . .
--------------------------------------------------------
< Throughout history, poverty is the normal condition >
< of man. Advances which permit this norm to be >
< exceeded -- here and there, now and then -- are the >
< work of an extremely small minority, frequently >
< despised, often condemned, and almost always opposed >
< by all right-thinking people. Whenever this tiny >
< minority is kept from creating, or (as sometimes >
< happens) is driven out of a society, the people >
< then slip back into abject poverty. >
< >
< This is known as "bad luck". >
< -Lazarus Long- >
<------------------------------------------------------>
http://www.aeroelectric.com
---
Message 14
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| Subject: | OV protection for PM alternators |
on juliet
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
All the Z diagrams show the overvoltage disconnect relay wired to the
output of the voltage regulator on permanent magnet alternators. Given
that the most likely cause of an over voltage is probably a regulator
failure, wouldn't it make more sense to disconnect the input to the VR
just in case the VR decided to overheat and make smoke? This would
require a two pole relay to disconnect the AC input but that should not
be a major problem since I was going to use a "40" amp rated automotive
relay with my 20 amp John Deere VR and alternator. I'm assuming that the
fusible link (actually a circuit breaker on my machine) would disconnect
the VR from battery current in case the VR shorted - but that might be a
bad assumption???
Ken
Message 15
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| Subject: | Re: Architecture for 2 batteries and 1 alternator |
--> AeroElectric-List message posted by: "glaesers" <glaesers@wideopenwest.com>
I have another failure mode question for Bob and the group to ponder:
The Eggenfeller Subaru Engine electrical architecture, described in their
on-line installation manual, has a single 4PDT switch which is used for the
engine Master Bus Switch - powers pumps and ignition from either the Main or
Aux battery It also has a single 4PDT Fuel Pump Select switch. (see
http://www.wideopenwest.com/~glaesers/RV7-Electrical-Architecture.html -
bottom figure OR: http://www.jlc.net/~fcs/EAA_IG/Emotor1of7.jpg and
http://www.jlc.net/~fcs/EAA_IG/Emotor2of7.jpg)
These two switches are both potential single points of failure. If either
fails, lots of silence. On the plus side (?), both Main and Aux positions
of both switches should be tested before each flight, and once in their
normal positions, neither would be moved inflight unless an abnormal
situation occurs (some failure the switch is supposed to solve!)
So, how risky do you consider this design? Can you suggest a more robust
design? Any alternatives I've dreamed up so far just add complexity and
potential for switch mis-management.
Or am I just looking for problems that aren't there? I'm not looking to
nit-pick their design, but if there is a more robust solution, I'm certainly
interested (and I suspect others will be as well).
Thanks,
Dennis Glaeser
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<rnuckolls@aeroelectric.com>
> >> My question is:
> >> what kind of failure could occur which would NOT trigger the LV
> >> warning, but
> >> could drain the batteries?
> >
> > None
>
>There is always failure of the LV warning itself.
But it's pre and in-flight testable. The LV warning light is
the first thing to come to life when you turn on the battery
master. Due notice of the LV warning light activity should
be a part of a pre-flight checklist. The ONLY time a LV warning
light gets exercised, is when the alternator is off or failed . . .
which is a very low percentage of total operating time . . . i.e.,
the warning light system is very low operating stress and most
use LEDs so they have very long projected service life. Last,
for LV warning failure to participate in a tense situation
while airborne requires a DOUBLE failure . . . that of the LV
warning light followed by failure of the alternator.
All things considered, the lowly LV warning light offers a
very robust, active notification of alternator failure that's
about as reliable as any architecture I can think of.
Bob . . .
Message 16
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
At 02:42 PM 8/22/2004 -0400, you wrote:
>--> AeroElectric-List message posted by: <bakerocb@cox.net>
>
>Message Previously Posted by Brian Lloyd
>
><< > Close . . . but it's not "field collapse" that we're shorting
> > out but counter EMF of the motor which is acting like a generator
> > during the motor's spin down interval.
>
>I had a really weird starting problem on my Comanche for a number of
>years that turned out to be related to this. The problem started when
>we replaced the engine and the new engine came equipped with a
>retard-breaker magneto (shower of sparks). It seemed to me that the
>engine was always harder to start now. We ended up replacing batteries
>and starters in an attempt to remedy the problem to no avail.
>
>Then I noticed one day that the engine didn't really start until
>shortly AFTER I released the starter button. I found that I could get
>relatively good starts by very short cranking intervals. Paying extra
>close attention I noticed that, not only did it start after I released
>the button is was like 1/2 second after releasing the start button that
>it really started. Everything in the shower of sparks system tested
>properly as did both running and starting ignition timing.
>
>I then traced down the wiring and found that whoever had wired the
>shower of sparks system had wired the retard relay to the starter side
>of the starter solenoid. When the engine fired and kicked the Bendix
>out, the starter spun up to a high speed. When I released the start
>button the back EMF from the starter held the retard relay in keeping
>left mag retarded and the right mag off until the starter spun down.
>Of course it didn't run right. I then moved the power for the retard
>relay from the output of the starter solenoid to the coil of the
>starter solenoid (solenoid pulled in by application of 12V) and the
>problem was solved. I tried to explain the problem and solution to the
>A&P and IA who had been working on the airplane and they just looked at
>me like I was speaking Swahili. Brian Lloyd >>
Excellent example of this phenomenon. Another example is the pinion gear
retraction delay experienced by folks who try to wire PM motor starters
from Skytec exactly like the wound field motor starters from B&C. Voltage
generated by the motor during spin-down keeps the pinion gear engaged for
several seconds after the starter button is released.
>Here is the situation: I have built and am flying a KIS TR-1 amateur built
>experimental airplane with a TCM IO-240 B9B engine in it. It has a B&C
>starter that uses an on-starter solenoid to both complete the electrical
>circuit to the starter motor and engage a pinion gear. Electricity gets to
>the starter via a conventional starter contactor which is activated by a
>push button on the instrument panel that sends 12 volts to the coil of the
>starter contactor. On the starter output side of the starter contactor I
>have a single electrical connection going to a 5 amp fuse then splitting
>to go to both a starter engaged light on the instrument panel and to the
>voltage input pin of a Unison solid state SlickSTART starting vibrator.
>
>During cranking the retard breaker points of the left magneto feed rapid
>high voltage pulses from the starting vibrator to the four upper
>sparkplugs slightly after piston top dead center. Also during cranking the
>normal 26 degrees before top dead center points of the left and right
>magneto are grounded out by internal functioning of the starting vibrator
>and my right magneto switch on the instrument panel which is off during
>cranking.
>
>My engine does not start cleanly it seems to stumble around for awhile
>after it initially fires and I have taken my finger off the starting
>switch. Based on your experience above I now suspect that the starting
>vibrator may continue to keep only the top four plugs firing at slightly
>after top dead center even after my finger is off the start switch for
>some period of time because the starting vibrator is getting some counter
>EMF input current from the starter motor as it winds down. Once that input
>current dies down the engine runs normally because the left magneto upper
>plugs start to fire at 26 degrees before top dead center and, if I have
>switched the right magneto on by that time, the lower plugs also will be
>firing at that point.
>
>I am now contemplating rewiring in order to feed the starting vibrator
>from the starting contactor coil input terminal via a 5 amp fuse and leave
>the starter engaged light connected to the starter contactor output
>terminal via its own fuse.
>
>What is your assessment of the situation? Thanks again for all that you
>contribute to this list I have learned a tremendous amount from your inputs.
>
>OC
>
>PS: The written instructions from Unison do call for the input to the
>SlickSTART to come from the output side of the starter contactor. As a
>side note I had a very difficult time wiring the SlickSTART into my plane.
>All of the written guidance from Unison was couched in cook book terms of
>how to replace an existing starting vibrator on a type certificated
>aircraft with theirs. Reverse engineering from a known system was the only
>way to figure out how 3 of the 5 pins (other than voltage in and ground)
>were supposed to be connected. Initial queries to Unison yielded a
>marketing answer that was completely wrong and led to miswiring.
>Fortunately through some personal trouble shooting and persistent contacts
>with Unison technical types I was eventually able to break the code.
Taking power to run the SlickSTART or Shower-of-Sparks should NOT come
from main starter power path downstream of the starter contactor for
exactly the reasons people are discovering in stories cited above.
Here's an article I did some years ago on Shower-of-Sparks
http://www.aeroelectric.com/articles/Shower-of-Sparks/ShowerOfSparks.pdf
which details how to control the ignition boost system from the same fuse
or breaker that energizes the starter contactor. This approach maintains
isolation between the ignition power and eliminates any possiblity that
starter motor counter-emf will upset the ignition system. I'm amazed that
Unison wouldn't know better.
Bob . . .
---
Message 17
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| Subject: | Antenna Placement. |
--> AeroElectric-List message posted by: "Dean Psiropoulos" <deanpsir@easystreet.com>
I read the antenna section of Lectric Bob's book but didn't see anything
about proper placement of them. I purchased commercially available antennas
for Transponder, Marker Beacon and a combination VOR/LOC/Glideslope. I want
to install the VOR/LOC/Glideslope on the bottom of the fuselage below the
horizontal stabilizer of my RV-6A. I'm thinking this should not be a
problem and when you're in the air it would seem like the optimum place for
it! But I'm no antenna expert so is this a good place to put it? Or is
there a better one? Do I need a splitter to separate LOC/VOR signals from
Glideslope (read something about this in Lectric Bob's book but not quite
sure if I need it)? Also, I've heard that one should separate receive
antennas from transmit antennas like comm and transponder. How far from
other antennas should communication and transponder antennas be placed? If
two comm. antennas are installed, how far apart from each other should they
be? How far from transponder antenna should the comm. antenna be placed?
Any other words of wisdom on antenna placement? Thanks.
Dean Psiropoulos
RV-6A N197DM
Panel and wiring
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