Today's Message Index:
----------------------
1. 04:43 AM - Subject: Tach P-lead feed (William Bernard)
2. 06:31 AM - Re: Re: Whelen strobe current draw (Robert L. Nuckolls, III)
3. 07:01 AM - Re: Documentation methods to print .pdf (Robert L. Nuckolls, III)
4. 07:54 AM - Re: Z-13 and Dual Electronic Ignitions (Joel Harding)
5. 08:38 AM - Re: "Charred" Fast-On termnials (Robert L. Nuckolls, III)
6. 09:25 AM - Re:Ammeter needle fluctuation (CANDO16@aol.com)
7. 09:45 AM - Re: Z-13 and Dual Electronic Ignitions (Robert L. Nuckolls, III)
8. 11:12 AM - Avionics bus (Terry Watson)
9. 11:19 AM - Small Relay Diodes (Mark Phillips)
10. 11:33 AM - MPJA Meters (Eric M. Jones)
11. 12:15 PM - Alternator output (again!) (Mark Phillips)
12. 01:06 PM - Re: Small Relay Diodes (Robert L. Nuckolls, III)
13. 02:20 PM - Re: MPJA Meters (Robert L. Nuckolls, III)
14. 04:39 PM - Re: Z-13 and Dual Electronic Ignitions (czechsix@juno.com)
15. 08:46 PM - Re: Z-13 and Dual Electronic Ignitions (David Carter)
16. 08:51 PM - Re: Alternator output (again!) (David Carter)
17. 10:46 PM - Re: Magneto buzz box circuit (David)
Message 1
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| Subject: | Tach P-lead feed |
--> AeroElectric-List message posted by: "William Bernard" <billbernard@worldnet.att.net>
Neil, I ran my tach from the P-lead by wiring the tach through a SPST On-On switch.
This way, only one mag was used at a time and the choice was up to the pilot.
I've also seen this done using a switch with monentary contact for one pole,
but this makes a mag check a 3 handed operation.
Hope this helps.
Bill
Message 2
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| Subject: | Re: Whelen strobe current draw |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 11:22 PM 5/9/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: Bill Irvine <wgirvine@yahoo.com>
>
> > So, if we assume that the strobe outlets produce a
> > flash once every 860 milliseconds, then Outlets 3 42
>
> > watt/seconds divided by .86 seconds is 48 watts, or
> > 4 amps in a 12 volt system. This 4 amp "event" is
> > alternating with Outlet 1. Therefore, the power
> > pack is drawing 4 amps continuously, am I right?
>
>I'm no expert on this, but keep in mind that for the
>CF (Comet Flash) power supplies, everytime they
>"flash", they actually produce four flashes in very
>rapid succession. If the sum total of the four
>flashes is 42 joules, then your calculations might be
>correct. But if each one of the four flashes is 42
>joules, then you will be off by a factor of four.
Intuitively, one can assume that it's 44 Joules total.
I've built strobes for photography in years past that
called for energy levels of 10 to 200 Joules per
flash. Some tubes rated at 20 Joules are good for
about 1 flash per second lest they get REALLY hot
and break. The 200 Joule tubes had flash paths approaching
6" long and could only be flashed at full power about
once every 3 or 4 seconds . . . I've burned the
bejabbers out of a finger or two learning about
the inefficiency of flash tubes . . . for every
watt you put into them, you don't get but a few
hundred milliwatts of light . . . the rest comes
off as heat. Unless the CF system has really
beefy flash tubes, it's unlikely that you're
going to push 164 watt-seconds of snort into
them every flash cycle.
Bob . . .
Message 3
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| Subject: | Re: Documentation methods to print .pdf |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 11:37 PM 5/9/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "David Carter"
><dcarter@datarecall.net>
>
>Thanks, Bob, for the patience to give an informative (long) reply to help us
>get going on our documentation and design work.
>
>Started modifying Z-13 for my RV-6 with John Deere PM alternator ("dynamo")
>as the only alternator and two batteries, to power my Mazda rotary engine.
>
>Making progress deleting the "std alternator, regulator, & mags", then
>looking up "block names" in the Blocks window and the "insert blocks", by
>name, into dwg (switches, dots, etc). Re-routing lines and having a great
>time. I'll put the dwg out for peer review when done - hopefully in .pdf
>format!
>David Carter
Publish in both .pdf and .dwg if you want input from the
community. This lets users of capable drafting programs
open, edit, highlight, etc on the original for return to
you. .pdf is fine for simple sharing but in the development
phase, you'll get higher quality feedback from folks who
can work with the original.
While we're on this topic: Somebody published a link to
a builder site last week where a rather detailed power
distribution diagram which I've posted at:
http://216.55.140.222/temp/RV-9_Electrical.pdf
Without getting into specifics on the architecture,
permit me to point out the value in making drawings
for your project as page-per-system documents. The
power distribution diagram is best limited to defining
architecture . . . how the system functions. The
existence of circuit protection, a switch and a wire
gage coming off the main bus with an arrowhead pointing
to "Landing Light P.22" is sufficient to convey understanding
as to the total number of features in the system.
The page-per-system technique also lets you avoid
dense groupings of long parallel wires that migrate
across 50% of the drawing. The wiring diagram for
a Mooney is a sheet of paper about 3' wide and
8' long . . . it's one of the most user unfriendly
documents I've ever seen.
It's much easier to do 20 pages for a system
that to do one . . . trust me. Been there, done
that and won't do it again.
Bob . . .
Message 4
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| Subject: | Re: Z-13 and Dual Electronic Ignitions |
--> AeroElectric-List message posted by: Joel Harding <cajole76@ispwest.com>
On Friday, May 9, 2003, at 10:25 PM, Robert L. Nuckolls, III wrote:
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <bob.nuckolls@cox.net>
>
> At 05:20 PM 5/8/2003 -0600, you wrote:
>> --> AeroElectric-List message posted by: Joel Harding
>> <cajole76@ispwest.com>
>>
>> Norm,
>> I have been contemplating many of the same ideas you just presented.
>> I
>> started out with Z-11 and added dual electronic ignitions. Then I
>> took
>> the Lightspeed recommendation to install a small 4.5 A H aux battery
>> as
>> a backup for one of the ignitions, and started thinking about using it
>> as a second power source for the essential bus. But then, like you I
>> began thinking why not install a disconnect between the main and
>> essential bus and use it as like an avionics bus since most of the
>> same
>> items would be on both.
>> The questions I have are:
>> 1. What are the negative consequences of installing a switch between
>> the main and essential buses?
>>
>> 2. Is a contactor needed with the small aux battery?
>>
>> Joel Harding
>
> What failures do you anticipate that you would be needing
> the second battery to power the e-bus? If you do reasonable
> preventative maintenance on the main battery AND do a load
> analysis that shows your main battery will carry e-bus
> loads for duration of fuel, I think I'd leave the second
> battery for ignition only. In fact, with Z-11 and dual
> 17 a.h. batteries, you get 34 a.h. of cranking. You have
> a less than two-year old battery in aux slot to carry
> engine loads only. You've got a fresh battery in main
> slot to carry e-bus loads only (I'd shut off one ignition
> during alternator out operations).
>
Bob,
The main incentive I had for going down this path was finding a simpler
method of incorporating the dreaded avionics bus into your essential
bus architecture. I know this is a major point of contention for you,
but I find myself dealing with the reality of a manufacturers
recommendation to provide protection for certain components, and I'm
too far into the stream to change horses. More important to me than
the failure modes was finding a way to simplify by combining the
avionics bus and the essential bus by isolating the main and essential
busses during starting. The aux bus backup was a lower priority
consideration to allow me to have some of these sensitive instruments
powered up during start without exposure to the brownout situation you
have discussed, and secondarily to provide a second power source for my
electronic flight instruments. I know this kind of talk probably makes
you crazy, but in my never ending quest to expose my ignorance of
electronics, I was compelled to present it to you.
I would appreciate your consideration of this idea.
Joel Harding
Message 5
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| Subject: | Re: "Charred" Fast-On termnials |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Hi Bob,
After six years and 800 hours I am re-doing the panel in my RV-6. Upon
disassembly, I found that the fast-on terminals at my strobe switch
Were somewhat charred looking. All of the other fast-on terminals looked
like new. To my knowledge, the strobe (or wiring) never failed during the
800 hours of service. The strobes (Wheelen Comet Flash) were on for every
one of those 800 hours.
I am going to mail you the charred terminals. When you get the terminals,
I would appreciate your comments by e-mail.
Hmmm . . . yes, I would like to see them.
Thanks for taking the time to bring this
to my attention.
Mark,
I've inspected your sample terminals, photographed them
and posted the photo at:
http://216.55.140.222/temp/NonPIDGFastOn.jpg
I'm also sharing this note with the AeroElectric-List.
The plastic used on these terminals has lost its "plastic".
The material has become quite brittle. Have any other terminals
on your switch panel shown discoloration? You might
try the "squeeze" test on the insulation grip on other
terminals to see if they're still flexible.
You can see striations in the coloring where the plastic
is a darker brown in a pattern that matches tooling
marks on the terminal itself. What we see here is suggestive
of a chemical change to the plastic aggravated by heating.
Microscopic examination shows some transfer of plastic
to the terminal surface.
Check the remaining terminals on the panel for
evidence of lost tension at the insulation grips. These
are non-PIDG style terminals and at-risk for that
kind of behavior.
If this is the only problem-terminal of the bunch,
and given the good appearance of plating on the terminal's
metal parts, I don't think this joint was in imminent
danger of failure nor are other terminals marching
toward failure. The terminal you sent me WAS running warm.
I'm surprised that strobe system current was high enough
to single out this terminal for abuse.
You might be well served to replace the strobe switch
(it too is a source of heat if the normally open contact
is getting corroded) and the other terminals on the
switch.
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 6
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| Subject: | Re:Ammeter needle fluctuation |
--> AeroElectric-List message posted by: CANDO16@aol.com
I have an RV-6 with an alternator and a Vans adjustable voltage regulator.
I've noticed the ammeter stabilized at higher Rpms (ie: climbout, runups,
etc.), but lower and medium RPMs the ammeter swings between + and - ranges.
It, also, seems to be rather erratic, in that it will be stable at lower
Rpms sometimes. My voltage reg. seems to be putting out 15V consistently
also....I'd appreciate any input you might have...Thanks Greg 319GH
Message 7
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| Subject: | Re: Z-13 and Dual Electronic Ignitions |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>
> >
>Bob,
>The main incentive I had for going down this path was finding a simpler
>method of incorporating the dreaded avionics bus into your essential
>bus architecture. I know this is a major point of contention for you,
>but I find myself dealing with the reality of a manufacturers
>recommendation to provide protection for certain components, and I'm
>too far into the stream to change horses. More important to me than
>the failure modes was finding a way to simplify by combining the
>avionics bus and the essential bus by isolating the main and essential
>busses during starting. The aux bus backup was a lower priority
>consideration to allow me to have some of these sensitive instruments
>powered up during start without exposure to the brownout situation you
>have discussed, and secondarily to provide a second power source for my
>electronic flight instruments. I know this kind of talk probably makes
>you crazy, but in my never ending quest to expose my ignorance of
>electronics, I was compelled to present it to you.
> I would appreciate your consideration of this idea.
A little disappointed perhaps but not crazy. And the goal
here is not to please me or any body else on the list.
I've often suggested that folks are better off with a system
they understand and are comfortable with than to be worrying
about something unique to their level of understanding.
Keep in mind that the vast majority of SE aircraft flying today
are wired not unlike the CessnaBeechPiperMooneys of decades
gone by . . . including OBAM aircraft. Airplanes wired
per the Z-drawings are rare in comparison with the total
fleet of aircraft.
When I ask people to justify their wish to modify any
of the systems we've published, it's not because I have
any notion of convincing them to "do it my way." My
query is aimed at acquiring insight as to some point
of engineering I may have overlooked. The Z-drawings
have evolved a lot over the last 10 years and I'd be
foolish to believe they should not evolve further.
My job is not to persuade you to do anything. My
job is to help you understand how the system works.
Your job is to craft a system that is not distracting
because of concerns or misunderstood operation. So
in answer to your questions:
You can certainly add a switch in series with normal
feedpath diode to service as an "avionics master"
You don't need to use a contactor for an aux battery
unless the battery is robust enough to aid in cranking
and/or it is your intent NOT to use it to assist the main
battery in cranking. Indeed, when the automatic aux
battery management concept was published in Sport Aviation
about 6 years ago, the aux battery was perhaps a 4-6 a.h.
device connect to the bus via a 30A power relay like our
S704-1.
May I suggest the following actions which may work
toward mitigating your concerns? Give me a list of
folks who have supplied you with equipment that they
claim is "sensitive" . . and let's at least ask them
to provide a justification for their assertions
based on physics.
I presume you followed the conversation
with Electronics International over the last two weeks.
It turns out that they haven't a clue as to why their
products should or should not be "protected".
While they claimed credit for full compliance under
TSO requirements that include DO-160 testing, they
didn't truly understand the significance of the tests
they paid money to accomplish. Nor did they understand
the significance of that testing with respect to their
customer's reasonable expectations.
In EVERY case I've looked at over the past 15 years,
not one company asking for an "avionics master switch"
was able to enlighten me with an explanation. In more than
half the cases, they admitted that there was no
justification and that the topic of avionics master
switch was part of the boiler-plate used to craft installation
manuals since the 60's and nobody has ever bothered to
review that requirement and take it out of the book.
I don't know if the outcome of such an exercise would influence
the way you configure your airplane and it doesn't matter.
Bottom line is that what ever goes into YOUR airplane
should minimize your worries as an owner and maintainer
of the airplane so that you can maximize your performance
as the pilot of that airplane.
Bob . . .
Message 8
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--> AeroElectric-List message posted by: "Terry Watson" <terry@tcwatson.com>
Bob,
Have you had any progress (or tried) convincing Greg Richter at Blue
Mountain Avionics that their EFIS-1 doesn't need to be on an avionics bus?
Terry
RV-8A
Blue Mountain EFIS-1
Message 9
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| Subject: | Small Relay Diodes |
--> AeroElectric-List message posted by: Mark Phillips <ripsteel@edge.net>
It it considered good practice to add diodes across the coils of small
relays such as would be used for flap controls or trim relays when using
stick switches? I am using a 3PDT relay for landing light/flasher
control that has a 100 ohm coil. Z-18 shows one, but they don't appear
on other drawings. If so, a 1N4001 or equiv. would work?
Advisable or not necessary?
Thanks
Mark Phillips
Message 10
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--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
I subscribed to the Marlin P. Jones Associates (no relation) e-mail special and
bought their TRMS RS232 Multimeter, the $89.95 Meter. All I gotta say is holy
cow! If you need a multimeter, appreciate and use this kind of technology, check
this one out.
http://www.mpja.com/productview.asp?product14521+TE $89.95 (TRMS and measures temps with supplied thermocouples)
http://www.mpja.com/productview.asp?product14311+TE $49.95 (standard but still incredibly impressive).
Caveat emptor, but this seems like an amazing deal to me!
Eric M. Jones
When trouble arises and things look bad, there is always one individual who
perceives a solution and is willing to take command. Very often, that individual
is crazy.
--Dave Barry
Message 11
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| Subject: | Alternator output (again!) |
--> AeroElectric-List message posted by: Mark Phillips <ripsteel@edge.net>
Not sure if I have a problem, but here goes:
Received my B&C L40, belt included and installed it. Belt was about 6"
too long, called B&C and they gave me a different belt #, purchased it
and it fits great. But the belt was so short it wouldn't even fit
around the flywheel- had to take it off to install the belt. This
flywheel obviously has a smaller than "usual" pulley on it.
Checked the Lyc. manual for pt# 68867 flywheel (oops! It's really a
"SUPPORT ASSY., Starter ring gear 10/12 pitch, 1.91:1") There are other
"flywheels" listed with 2.55:1 and 3.25:1 pitches. (What's THIS all
about, anyway?) listed for my E3D, which originally had A/C and may
explain the different "pitches"?
What I'm curious about is alternator performance. Measuring the two
pulleys yields a ratio of approx. 2.73:1, which would give only 3276
rpms @ 1200 crank speed, and 7371 @ 2700. Are these speeds too low or
should I be searching for a larger "SUPPORT ASSY...................."?
Don't know if the alternator pulley could be any smaller- it's only
2.75" across.
I searched the archives for the chart Bob posted a couple of weeks ago
about alternator output, if I recall, with no joy. Anyone still have
this?
From the PossumWorks
Mark - do not archive -
Message 12
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| Subject: | Re: Small Relay Diodes |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:17 PM 5/10/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: Mark Phillips <ripsteel@edge.net>
>
>It it considered good practice to add diodes across the coils of small
>relays such as would be used for flap controls or trim relays when using
>stick switches? I am using a 3PDT relay for landing light/flasher
>control that has a 100 ohm coil. Z-18 shows one, but they don't appear
>on other drawings. If so, a 1N4001 or equiv. would work?
>
>Advisable or not necessary?
>
>Thanks
>Mark Phillips
It almost never hurts. It's a good idea for larger loads
like contactors that store probably 10-50x more energy
than their little relay counsins.
First, keep in mind that energy in the "spike" that comes
off a relay or contactor coil is 99.9% used up in the
spreading contacts of the controlling switch. So adding
a diode to any coil is to increase the life of the switch.
The 100 mA or so relays don't represent much risk to a
switch but then, a 1N400x diode is pretty cheap and easy
to install . . . so why not?
Bob . . .
Message 13
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 02:33 PM 5/10/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>
>I subscribed to the Marlin P. Jones Associates (no relation) e-mail
>special and bought their TRMS RS232 Multimeter, the $89.95 Meter. All I
>gotta say is holy cow! If you need a multimeter, appreciate and use this
>kind of technology, check this one out.
>
>http://www.mpja.com/productview.asp?product14521+TE $89.95 (TRMS and
>measures temps with supplied thermocouples)
>
>http://www.mpja.com/productview.asp?product14311+TE $49.95 (standard
>but still incredibly impressive).
>Caveat emptor, but this seems like an amazing deal to me!
It used to be that to ask for better than 3% accuracy
in ordinary test tools was a stretch, nowadays 1% is
commonplace. I purchased my first new instrument the day
I got a job at Boeing (fall of 1961 . . . $86.00/wk).
It was shinny new Triplet Model 630 and I gave about $70
for it. This would have been a typical 3% instrument of
the era. According to the inflation calculator at
http://www.westegg.com/inflation/
. . . that $70 instrument would cost me $410.00 today
or working backwards, the $50 instrument Eric cited
would cost $8.60 in 1961 dollars. This is a really
neat business to be in. We can do more for less dollars
tomorrow. Now if government could be taught to operate
the same way . . .
As I recall . . . one could buy a C-172 for about
$15000 when I worked there. According to inflation
calculator, the airplane should sell for about $88,000
today and IT wouldn't even fly better than it did in
1961 . . . wonder where we went wrong.
Bob . . .
Message 14
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| Subject: | Re: Z-13 and Dual Electronic Ignitions |
--> AeroElectric-List message posted by: czechsix@juno.com
Bob,
I'm a bit baffled on your reply that "if you have two engine driven power
sources, then you don't need two batteries". A couple months ago we had
a lively exchange where you were poo-pooing my questions about tying
electronic ignition leads directly to the battery to eliminate failure
points between the battery and the battery bus (something about swatting
gnats). Then when you realized I was talking about DUAL electronic
ignition, you said that I should have dual batteries. My plan up until
then had been to go with Z-13, single battery/dual alternator. But this
does mean that the single battery is a single point failure that will
result in engine failure if it's integrity is destroyed. Someone
recently had a case where their battery lead bolt broke clean off (wasn't
it a Powersonic RG battery?).
Anyway, I still don't know what to think....I've gotta believe that
complete battery failure with an RG is rare, but nevertheless I thought
maybe it would be better to go with dual batteries. The configuration
I've tentatively settled on is the one Klaus Savier recommends....single
alternator and single main battery, plus a very small standby battery
that is charged through a Schottky diode to isolate it from everything
else, and runs one of the ignition systems. This seemed to me to be the
lightest, simplest and cheapest setup that offered assurance of ignition
system redundancy. It doesn't have the convenience of running an SD-8 if
the main alternator quits, but since I'm running a B&C main alternator I
felt the odds of being stuck somewhere (albeit safely on the ground) away
from home with my alternator dead to be pretty low risk and probably
worth the compromise in the long run.
I was just amused at your statement on Z-13 because I thought that you
did not advocate this setup for dual electronic ignition?
--Mark Navratil
Cedar Rapids, Iowa
RV-8A N2D finishing...
Time: 09:28:57 PM PST US
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Z-13 and Dual Electronic Ignitions
If you have two engine driven power sources, then you don't
need two batteries. I'd run a Figure Z-13 system and run
both ignitions from the battery bus. Further, if you're really
tight on weight, you can down-size the battery to something on
the order of 10 a.h. if you don't mind the extra cost of the
smaller battery.
There are LOTS of different ways to hook things up that will
FUNCTION. What we should be trying to do is honor the wisdom
of a 13th century philosopher, William of Ockham who opined
"Plurality should not be assumed without necessity" . . . or
in more modern parlance, don't make it any more complex
than necessary. If you deduce some shortfall in the suggested
system cited above that drives a necessity for adding complexity
to the system, let's talk about it.
Bob . . .
The best thing to hit the internet in years - Juno SpeedBand!
Surf the web up to FIVE TIMES FASTER!
Message 15
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| Subject: | Re: Z-13 and Dual Electronic Ignitions |
--> AeroElectric-List message posted by: "David Carter" <dcarter@datarecall.net>
Mark Navratis (czechsix?),
I am the least qualified to even attempt a comment here, but that never
stops me from trying.
I, too, am in process of modifying Z-13 for my all electric Mazda rotary
engine. I, too, am concerned about a battery failure, and equally concerned
about battery contactor failure. (I don't have a great fear of the
probability of either, but believe there is enough anecdotal history to make
me design my system so either or both will be a "no sweat" situation (Bob's
"prime directive").
That is why I'm going to use a Permanent Magnet Alternator (John Deere 35,
55 or 85 amp) (the "alternate alternator is labeled "Dynamo" in Z-13 - this
is a PM alternator).
- PM alternators/dynamos operate with no need for a battery - ever.
-- So, if battery fails, PM Alternator continues to put out
regulated DC to the left hand (in Z-13) terminal of the battery contactor,
which is where the wire that feeds the Battery Bus connects, which means
that the battery can short, open, or melt and all run out a hole in the
bottom of the plane -- and the battery bus, essential bus, and all electric
engine will hum away on alternator power.
I'm going to run only a single alternator - the PM alternator. They are
supposed to be so reliable, and totally independent of the battery, that I
don't see why I'd want all the "risks" that come with a "battery dependent,
and battery contactor dependent std alternator.
I'm adding a second battery, so will have a "2 battery, single PM
alternator" system.
- Haven't decided if I want to use 2 regular size batteries (may need
that for "battery-only electrical endurace" close to equal to "fuel
endurance"): 1) IF my electrically fed and fired engine current draw is
not too great (don't have all the current draw info yet for 2 ignition
coils, efi pump (1 on at a time except for T.O. & land), and Tracy Crook's
EC-2 ignition-injection controller (engine computer), THEN may go with a
small expensive light weight battery isolated just for the engine.
2) If need the extra juice, and if need the extra
amp capacity for cranking engine, will go the easy, heavier, cheaper way and
go with 2 17AH batteries (this is what I feel will be my choice - makes
annual battery replacement and rotation simple, lower cost, better
reliability, and I don't care about the difference in weight - my Mazda
rotary already saves me about 20#.)
Does this help any, in trying to sort things out? If not, please help me
understand more & better.
David Carter
----- Original Message -----
From: <czechsix@juno.com>
Subject: Re: AeroElectric-List: Z-13 and Dual Electronic Ignitions
> --> AeroElectric-List message posted by: czechsix@juno.com
>
> Bob,
>
> I'm a bit baffled on your reply that "if you have two engine driven power
> sources, then you don't need two batteries". A couple months ago we had
> a lively exchange where you were poo-pooing my questions about tying
> electronic ignition leads directly to the battery to eliminate failure
> points between the battery and the battery bus (something about swatting
> gnats). Then when you realized I was talking about DUAL electronic
> ignition, you said that I should have dual batteries. My plan up until
> then had been to go with Z-13, single battery/dual alternator. But this
> does mean that the single battery is a single point failure that will
> result in engine failure if it's integrity is destroyed. Someone
> recently had a case where their battery lead bolt broke clean off (wasn't
> it a Powersonic RG battery?).
>
> Anyway, I still don't know what to think....I've gotta believe that
> complete battery failure with an RG is rare, but nevertheless I thought
> maybe it would be better to go with dual batteries. The configuration
> I've tentatively settled on is the one Klaus Savier recommends....single
> alternator and single main battery, plus a very small standby battery
> that is charged through a Schottky diode to isolate it from everything
> else, and runs one of the ignition systems. This seemed to me to be the
> lightest, simplest and cheapest setup that offered assurance of ignition
> system redundancy. It doesn't have the convenience of running an SD-8 if
> the main alternator quits, but since I'm running a B&C main alternator I
> felt the odds of being stuck somewhere (albeit safely on the ground) away
> from home with my alternator dead to be pretty low risk and probably
> worth the compromise in the long run.
>
> I was just amused at your statement on Z-13 because I thought that you
> did not advocate this setup for dual electronic ignition?
>
> --Mark Navratil
> Cedar Rapids, Iowa
> RV-8A N2D finishing...
>
> Time: 09:28:57 PM PST US
> From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
> Subject: Re: AeroElectric-List: Z-13 and Dual Electronic Ignitions
>
>
> If you have two engine driven power sources, then you don't
> need two batteries. I'd run a Figure Z-13 system and run
> both ignitions from the battery bus. Further, if you're really
> tight on weight, you can down-size the battery to something on
> the order of 10 a.h. if you don't mind the extra cost of the
> smaller battery.
>
> There are LOTS of different ways to hook things up that will
> FUNCTION. What we should be trying to do is honor the wisdom
> of a 13th century philosopher, William of Ockham who opined
> "Plurality should not be assumed without necessity" . . . or
> in more modern parlance, don't make it any more complex
> than necessary. If you deduce some shortfall in the suggested
> system cited above that drives a necessity for adding complexity
> to the system, let's talk about it.
>
> Bob . . .
>
>
> The best thing to hit the internet in years - Juno SpeedBand!
> Surf the web up to FIVE TIMES FASTER!
>
>
Message 16
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| Subject: | Re: Alternator output (again!) |
--> AeroElectric-List message posted by: "David Carter" <dcarter@datarecall.net>
Just looked at a curve for 80amp alternator - rpm on bottom, amps on left
vertical.
5th item down in list at http://216.55.140.222/temp/
David
----- Original Message -----
From: "Mark Phillips" <ripsteel@edge.net>
Subject: AeroElectric-List: Alternator output (again!)
> --> AeroElectric-List message posted by: Mark Phillips <ripsteel@edge.net>
>
> Not sure if I have a problem, but here goes:
>
> Received my B&C L40, belt included and installed it. Belt was about 6"
> too long, called B&C and they gave me a different belt #, purchased it
> and it fits great. But the belt was so short it wouldn't even fit
> around the flywheel- had to take it off to install the belt. This
> flywheel obviously has a smaller than "usual" pulley on it.
>
> Checked the Lyc. manual for pt# 68867 flywheel (oops! It's really a
> "SUPPORT ASSY., Starter ring gear 10/12 pitch, 1.91:1") There are other
> "flywheels" listed with 2.55:1 and 3.25:1 pitches. (What's THIS all
> about, anyway?) listed for my E3D, which originally had A/C and may
> explain the different "pitches"?
>
> What I'm curious about is alternator performance. Measuring the two
> pulleys yields a ratio of approx. 2.73:1, which would give only 3276
> rpms @ 1200 crank speed, and 7371 @ 2700. Are these speeds too low or
> should I be searching for a larger "SUPPORT ASSY...................."?
> Don't know if the alternator pulley could be any smaller- it's only
> 2.75" across.
>
> I searched the archives for the chart Bob posted a couple of weeks ago
> about alternator output, if I recall, with no joy. Anyone still have
> this?
>
> >From the PossumWorks
> Mark - do not archive -
>
>
Message 17
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| Subject: | RE: Magneto buzz box circuit |
--> AeroElectric-List message posted by: "David" <David@ChalmersFamily.com>
I want to put together a circuit to time my magnetos. Seems like the
mags appear as a capacitor, coil and switch in parallel. I need a
circuit to tell when the switch is closed. I did this previously by
feeding the output of a 555 oscillator into the points and looking for
the amplitude change on a scope but I'd like to build something that is
simpler to use - i.e has an LED or buzzer. Anyone got a schematic for a
simple buzz box?
Thanks
Dave Chalmers
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