Today's Message Index:
----------------------
1. 06:33 AM - Re: Re: 40amp Denso Aerosport Alternator (Robert L. Nuckolls, III)
2. 06:33 AM - Re: Antenna Locations (Robert L. Nuckolls, III)
3. 06:42 AM - Re: small high cca batteries (Robert L. Nuckolls, III)
4. 09:40 AM - Re: Re: 40amp Denso Aerosport Alternator (Ken)
5. 11:23 AM - Battery charger/desulphator (WRBYARS@AOL.com)
6. 05:44 PM - Re: Selective Radio Reception (Dave Morris \)
7. 06:46 PM - twisted wire pairs ()
8. 08:08 PM - Re: Selective Radio Reception (Fiveonepw@aol.com)
9. 09:41 PM - Re: 40amp Denso Aerosport Alternator ()
10. 10:01 PM - PTT SWITCH ()
Message 1
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| Subject: | Re: 40amp Denso Aerosport Alternator |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:50 PM 6/12/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: <gmcjetpilot@yahoo.com>
>
>
> >If an alternator runs away voltage wise, but is still connected to the
> battery, how many amps >would the battery draw at the point when the
> voltage is harmfully high? Isn't there some >inherent protection in
> having a circuit breaker in the main alternator output line? For
> example, >I have a 50-amp breaker on my 40 amp alternator.
>
> >Alex Peterson
> >RV6-A N66AP 624 hours
> >Maple Grove, MN
>
>
>Hello Alex:
>
>
>No I don't think that's going to work that way. The answer I believe is
>volts and amps are obviously different, and the circuit breaker works on
>current (amps) not voltage. Actually the CB is a thermal device and needs
>current (flow) to heat up and trip.
>
>
>If the volts go up, the battery will absorb so much and than, the system
>buss volts will climb and the amps may even drop due to Ohms law:
>
>Power = Volts x Amps,
>
>Pwr (constant) = Volts(up) x Amps(down)
>
>Bob N. could address this better than I but think Im in the ball-park.
>
>
>I also have a 50 amp CB on my b-lead (40 amp alternator). I had a short
>lived idea about putting a "crow-bar" on this 50 amp CB for the b-lead, to
>force it to trip (open, pop), just like Bob's crow bar on the voltage
>regulator CB. The big differnce is the CB on the VR is 5 amps and the
>b-lead CB we have is 50 amps. I decided against it.
>
>
>You can always reach over and manually pull the CB yourself if needed. May
>be one advantage of using a CB on the alternator vs. a fuse.
>
>
>A crow bar (SCR, silicon control rectifier) would be very large to "pop" a
>50 amp CB, but I am staying with my original position of not adding on any
>extra OV protection to an internally regulated alternator based on the
>unlikely chance of OV.
>
>
>The problem with a 50 amp CB is it might take 600% (300 amps) to cause it
>to trip, which might take .36-1 seconds. That might be too slow to help
>the radios. which is the theory of doing the OV protection in the first
>place. They make high amp SCR's that can take 300-500 amps for a second
>might be possible but too much to be practical (safe).
>
>
>If I wanted a b-lead disconnect, I would use a solid state relay to open
>the circuit directly, with out using dead short (crow-bar). With the crow
>bar you hope the CB trips fast enough to do good and fast enough before
>the crow bar melts.
>
>
>May be Bob N. could give us insight into why a 50amp crow bar would not
>work or would not want to do this. Again I am in the KISS camp, use the
>internal VR alternators OV protection as is and leave all the extras off.
>
>
>Cheers George (BTW Nice web site Alex)
The notion of using the b-lead circuit protection as a major
component of overvoltage protection surfaces from time to time.
Yes, a manually operable circuit breaker can be used to disconnect
a misbehaving alternator but this is a secondary task that may
best be accomplished other ways.
The b-lead circuit protection is useful only for isolating a
shorted b-lead feeder or an alternator with failed diodes.
This is an extremely rare event as the b-lead is generally short,
easily inspected for wear and diodes are many times more robust
than when they first migrated inside the alternator and replaced
the selenium rectifier stack about 50 years ago.
Automobiles use fusible links as b-lead protection.
An alternator is inherently current limited. Its b-lead protection
should be large enough to eliminate any nuisance trips. 60A breakers
on 60A alternator routinely nuisance trip in airplanes but nobody
wants to mount the phalanx of no-value-added paperwork it takes
to fix it on a certified ship.
When an alternator goes into runaway, it becomes a relatively
constant current power source that produces a stress on the battery
described in the paper:
http://www.aeroelectric.com/articles/Crowbar_OV_Protection/DC_Power_System_Dynamics_C.pdf
If the battery is in good shape then rate of rise for voltage
on the system is relatively benign - IF one chooses to live in
the DO-160 world where electro-whizzies are designed to withstand
20 volts for 1-second.
It's conceivable that a builder COULD choose to use a pullable
b-lead breaker combined with OV WARNING light and depend on
a good battery, and timely reaction to the warning light
to craft a manually operated ov protection system.
I don't think that's good design . . . certainly not the
best we know how to do.
In fact, there IS an elegant way to use solid state controls
to corral a runaway alternator. If one inserted a diode in
series with the altenrator's b-lead and placed a crowbar
module across the b-lead to ground, one could very
effectively bring a runaway alternator to heal by simply
shorting its output to ground. The crowbar module would not
need to be much larger than the current design . . . it only
takes 60-75 amps of load to stall a 60A alternator and it
would be all over in a heartbeat.
Problem is that adding a diode tosses away .6 to 1.0 volts
of alternator output which cannot be compensated for (built
in regulators are not adjustable). This means we'd have to
go inside the alternator to somehow boost it's output
by a volt or so. You would also need some kind of keep-alive
bias circuit (probably a resistor around the b-lead diode)
to make sure the crowbar module stays latched into an ON
state after it triggers.
There is a line of thought being considered to use this
technology but I don't have a combination that I'm satisfied
with yet.
Bob . . .
Message 2
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| Subject: | Re: Antenna Locations |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:12 PM 6/12/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "Tinne maha" <tinnemaha@hotmail.com>
>
>Bob/List,
>
>I have mounted my trasponder & comm antennas on the bottom of my fueselage
>21 inches apart. A source of unknown authority (i.e. the kit manufacturer)
>has advised that I need to separate the two by a greater distance for fear
>of comm interference from the trasponder. My source neglected to specify a
>minimum distance. Will you please advise?
>
>King KT-76A Transponder with a Garmin GNC 250-XL GPS Comm.
21 inches is fine.
Bob . . .
Message 3
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| Subject: | Re: small high cca batteries |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:36 PM 6/12/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "Ronald J. Parigoris"
><rparigor@suffolk.lib.ny.us>
>
>Hello Bob
>
>"I'd run one big battery with the larger alternator and
> use it to crank the engine. Use a smaller battery with
> the smaller alternator and close the crossfeed relay
> (S704 instead of S701) to share power between sides only
> if one alternator has died."
>
>Which diagram are you referring S704 and S701?
Z-14 is the diagram. S704 is a high current relay
used in lieu of S701 contactor as a cross-feed controller.
> >3) If the 2 sides are just connected, is the only downside that the
> >alternator with the
> >higher voltage will take the full load?
>
> "generally . . . but the only reason to connect both sides is
> if one alternator has quit."
>
>If the larger battery is a bit run down, or in bad condition and I put the
>smaller one in
>parallel to help a start up, would this be a bad thing?
How do you plan to go flying with a battery that is a
"bit run down"? Starting an engine generally takes
less than 10% of the battery's total capacity. It can be
a "lot run down" and still get the engine started. If
you ever have a sense of the battery being overtaxed during
cranking, then you've done too much ground operations without
ground power support or something is wrong and needs to
be investigated.
A whole lot of airplanes have flown for over 100 years
with one battery . . . just because you have two batteries
shouldn't drive you into a requirement to use both for
cranking unless that was an original design goal. As
I understand the current design goal, you want to have
the benefits of a dual alternator system that doesn't
rely on premium batteries so cost will be down along with
installed weight.
The suggestion was to install the minimal battery to
stabilize/filter the smaller alternator system and use
only one battery for cranking. If the goal is to use both
batteries, then the second battery needs to get bigger,
heavier and the S704 relay needs to be relaced with
an S701 contactor.
>If I run the radios and instruments on the smaller battery, if they were
>turned on when
>starting the motor off the larger battery only, is there any downside to
>doing this?
No
Bob . . .
Message 4
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| Subject: | Re: 40amp Denso Aerosport Alternator |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
If this will stall the alternator with a diode there, why wouldn't it
stall the alternator simultaneously with an opening OV contactor? I'm so
far not planning to remove my OV contactor ;)
Actually I also wonder if you can stall ALL alternators. Some (I believe
with 9 diodes) have been reported to start and run without a battery. Of
course that's not near as difficult as starting with a short on the
output...
Ken
>snip
> In fact, there IS an elegant way to use solid state controls
> to corral a runaway alternator. If one inserted a diode in
> series with the altenrator's b-lead and placed a crowbar
> module across the b-lead to ground, one could very
> effectively bring a runaway alternator to heal by simply
> shorting its output to ground. The crowbar module would not
> need to be much larger than the current design . . . it only
> takes 60-75 amps of load to stall a 60A alternator and it
> would be all over in a heartbeat.
>
> Problem is that adding a diode tosses away .6 to 1.0 volts
> of alternator output which cannot be compensated for (built
> in regulators are not adjustable). This means we'd have to
> go inside the alternator to somehow boost it's output
> by a volt or so. You would also need some kind of keep-alive
> bias circuit (probably a resistor around the b-lead diode)
> to make sure the crowbar module stays latched into an ON
> state after it triggers.
>
> There is a line of thought being considered to use this
> technology but I don't have a combination that I'm satisfied
> with yet.
>
> Bob . . .
>
>
Message 5
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| Subject: | Battery charger/desulphator |
--> AeroElectric-List message posted by: WRBYARS@aol.com
Greetings,
If anyone is thinking about buying a battery charger/desulphator, such as I
mentioned in my post a couple of days ago, here is a VERY good buy at this
web site.
Bill Byars
1949 T8F
_http://www.batteryweb.com/batteryminder.cfm_
(http://www.batteryweb.com/batteryminder.cfm)
Message 6
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| Subject: | Re: Selective Radio Reception |
--> AeroElectric-List message posted by: "Dave Morris \"BigD\"" <BigD@DaveMorris.com>
How bent is the antenna? Do the other 2 aircraft have horizontal or
vertical antennas? Have you tried hooking up a different antenna to the radio?
Dave Morris
At 09:13 PM 6/11/2005, you wrote:
>--> AeroElectric-List message posted by: Fiveonepw@aol.com
>
>My radio is
>Microair 760, bent whip bottom of fuse, and it doesn't matter whether I'm
>plugged
Message 7
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| Subject: | twisted wire pairs |
--> AeroElectric-List message posted by: <jlundberg@cox.net>
What type of twisted pair wire do you use for the headset and mic hookups in the
intercoms you all are talking about?? Where do you buy this wire?
I have been using shielded multiconductor milspec wire from Steinair and it has
been rather expensive but at least it is tefzel and its very durable stuff.
John
Message 8
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| Subject: | Re: Selective Radio Reception |
--> AeroElectric-List message posted by: Fiveonepw@aol.com
In a message dated 06/13/2005 6:45:35 PM Central Standard Time,
BigD@DaveMorris.com writes:
How bent is the antenna? Do the other 2 aircraft have horizontal or
vertical antennas? Have you tried hooking up a different antenna to the
radio?
>>>
My antenna is one of those $20-25 jobs from ACS (couldn't find in online
catalog)- it's a simple metal rod, maybe 1/8" dia with threads on one end to
attach the lead and bushing, runs through that insulating bushing and is bent about
40 degrees from vertical maybe 2" after it exits the fuse. Located about 6"
forward of the rear spar, offset about 6" to pilot's side of centerline. Coax
sheild is grounded to a bent-up corner of the doubler plate, about 2" from
antenna hole. Doubler is maybe 4x6", riveted to inside of skin.
The other RV driver had a really thin older antenna that appeared to have
seen better days, and recently replaced it with a used Comant style (not sure of
brand, but it has the fairing at the base) and I could hear him a little
better, but still nowhere as well as almost any other radio, unicom base, tower
or
a/c within at least 30 miles. The Cherokee trainer has a really old radio,
but the person flying it that day did say he wasn't familiar with other planes
not hearing him. No idea what antenna arrangement is like on that plane.
I hesitate to start experimenting with other antennas as my normal reception
picks up pattern traffic from airports 30-40 miles away (and they report
hearing me fine) as soon as I climb to pattern altitude, just not these two planes.
Mark do not archive
Message 9
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| Subject: | Re: 40amp Denso Aerosport Alternator |
--> AeroElectric-List message posted by: <gmcjetpilot@yahoo.com>
>Bob N wrote:
>Okay, it's your considered recommendation that if one
>purchases p/n (xxxxx) from supplier (YYYYY) then OV
>protection is not called for. You've cited data to support
>your advice. Now, how do we get this information into
>the hands of the greatest numbers of builders?
Bob, my advice is from a ranked amateur and offer it with no warrantee. You have
served to improve the knowledge and best interested of count less builders,
including myself. I dont think we need to disseminate my opinion further than
this list.
>George, you seem to have completely missed the point
>I've been trying to illustrate during this endless
>thread. YOU and many like you are building ONE airplane.
>You may have conversed with others to gather data
>on and make selection of specific components in
>which you have either trust supported by repeatable
>experiments or faith supported by the gross weight of
>anecdotal information. In either case, you're certainly
>free to go forward with your choice and I wish you well.
There are no one-size fits all solutions. I have not listed any specific part numbers
because frankly I dont want the liability. Second I have been honest that
getting detailed info on a Denso alternator and design in next to impossible
since all the engineers are in Japan. As far as anecdotal evidence, I have tracked
down as much info on how transistors fail, why and what characteristics
different transistors have. It is not a fact but a widely held electronics industry
expectation that transistor are VERY reliable. The external V-regulator
and crow bar is no doubt more bullet proof. I take your word on it based on
your experience and it makes sense. I think for most builders they take things
on faith and standard practice. No need to reinvent the wheel.
I think the hey my Denso has worked for 10 years with no problems is just that,
anecdotal. I agree. As far as tests, sadly are in Japan and in Japanese. I hear
the Japanese are good with electronics. I am sure Denso with 20-30 years making
alternators with internal VRs have tested them and done failure analysis.
Granted a car is not an airplane and I have no proof.
>Please understand that I write for thousands of builders
>working on thousands of airplanes being fabricated all
>over the world. Their choices for selection of a suitable
>alternator MIGHT include part number (xxxxx) and maybe
>they have access to supplier (YYYYY) but I would be
>remiss in my duties if I were to LIMIT my recommendations
>to this narrow range of choices . . . especially when
>I have no data from any repeatable experiments
>to support my advice. Further, there are MILLIONS of
>alternators with THOUSANDS of part numbers that will
>perform very well and free of concerns if we drive
>probability of hazardous failure down with layered
>systems architecture . . . this is a major component
>of FAILURE TOLERANT design. You ASSUME that a part
>will fail and then incorporate protection -OR-
>alternate technology (Plan B).
Bob, I understand all your recommendations. I understand from your analysis, lack
of information and judgment you cant endorse it. I think your opinions are
the most conservative and will provide a method of DC power production in an aircraft
that provides repeatable reliability and a level of safety required in
certified aircraft designs. However for me in a VFR RV (experimental) with an
engine that does not require electrical power (mechanical systems and self sustaining
ignition), I can get away with an alternate path to electric DC power
generation. This path is using an internal VR alternator with no extra external
OV protection. I have OV warning (large flashing red light) and a manual way
to disconnect the alternator output (b-lead) from the system thru a CB. Works
for me and me only.
Others have used the Denso 40 amp, aka Niagara, with good results. Again far from
rigorous scientific proof, but a collection of general facts, anecdotes and
opinion. My recommendation is inferior to the method of using an external alternator
regulator and an OV module, aka crow-bar, in a rigorous scientific way.
However my design will work OK as intended and be safe in my opinion, while
being lighter, simpler, and cheaper.
>When I handed control lock keys of an explosively
>launched recovery parachute controller to the pilot who
>was going to depend on that system to safe his life
>and perhaps his airplane, I could look him right in
>the eye and offer that I have done the best I know
>how to do. When I write words on this List and for
>the 'Connection, I believe am operating with that
>same sense of duty to offer the best and most
>universally useable information available. I am
>pleased that you have discovered what you believe
>is the ultimate solution to your system design
>goals and parts procurement issues. Please fly them in
>good health. The odds are definitely in your favor.
Mr. Nuckolls not to pander to you in anyway, sincerely you have single handedly
educated thousands of pilot/builders about electrical systems. The knowledge
of the aviation community in general is the better for your contributions. The
average aircraft (homebuilt) electrical system has improved due to your efforts.
I dont mean to undermine your methods, analysis or opinions. However I do
pick a choose what features I install in my electrical system. The most notably
is the internal regulated alternator. I think you have said this yourself,
If it can fail assume it will and what will happen when it does. I have analyzed
my system and find that all alternator failures will be passive and not a threat
to safety of flight FOR ME. (Dont try this at home, your mileage may vary
and this info is provided for entertainment purposes only, Sincerely Georges
Lawyers, Dwey-Cheat'em and Howe)
>But understand that I've obligated myself to operate
>in a wider arena and to offer advice that permits
>me to look any builder in the eye and offer that
>it's the best and most universally applicable
>technology I know how to do right now. I have no
>FAITH in the universal performance of all the
>automotive alternators available to the OBAM aircraft
>community around the world but I do have the
>knowledge of countless REPEATABLE EXPERIMENTS
>conducted to craft the most failure tolerant
>and hazard free systems I know how to do today.
Amen, I have no way, other than FAITH, that the Denso alternator will not hurt
me or the airframe, and the level of risk, is appropriate and I am willing to
accept it and understand it. I have determined that my old Collins transponder
and new Icom A200 (without OV protected power supply) may likely be damaged.
Other equipment is OV protected internally and if damaged the manufacture assured
me the damage would be repairable at nominal cost. Plan A never have an electrical
failure. My maintenance plan to assure reliability is checking electrical
volts and amps carefully for any sign/trend of impending failure, replace
battery on regular basis and never over load alternator. During flight test I
will thermocouple alternator to determine operating temps are acceptable. Blast
cooling tube will be installed.
> I'm not here to argue against the gospel of
>Nipon Denso or any other. I have tools called
>Failure Mode Effects Analysis, decades of experience
>with others who design, build and fly airplanes
>and a personal goal of understanding how things
>work and sharing that with anyone who has an
>interest. I cannot advise a builder to adopt a
>design philosophy that I do not understand or that
>he cannot understand AND CONTROL.
Bob, no one mounting the sermon; You are right you dont have ABSOLUTE control and
dont have complete understanding how the IC chip and transistor works in a
Denso. I have gone as far as I needed to see the truth, GOOD ENOUGH for me, no
more or less. I really think alternators with internal regulators are getting
better and soon will have failsafe internal regulators. The auto industry will
demand it and we will benefit from it.
Other alternators like Mitsubishi have also worked well, and from my research others
like Delco/Motorola/Hitachi have had poor service history according to the
Highway Safety foundation. The Denso has just happened to become the De-facto
choice for homebuilders, proven to be reliable in cars, industrial equip and
planes, size, weight and the dual internal fans.
I looked at the problem of over voltage, load dump, transient voltage and equipment
protection and found that it is acceptable that my system suffer an OV condition,
so reliably is moot. However I prey that it will be as reliable as I
think it will be and as others have experienced. The chance of fire or catastrophic
failure of the alternator is nill. I do run the risk of some equipment damage
if a rare OV occurred, but that may be limited to a few hundred dollars
of damage. That is where I am putting my faith, but this is a special system design
and meets my fault tolerance analysis.
If it can fail it will and any failure should not cause a hazard. Amen, we shall
now turn our Aeroelectric Hymnal to page XX.
>Bob . . .
All the best and I thank you again for forcing us to critically think thru out
systems. Even if it is not the perfect solution for ALL at least it is MY system
and I have knowledge of the risk and benefits. I am searching for the lightest
and most reliable electrical system I can get, and I accept the risk of an
OV as unlikely but an acceptable one. Bob I have learned a lot from your books
and forum.
Thanks again. George
---------------------------------
Stay connected, organized, and protected. Take the tour
Message 10
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--> AeroElectric-List message posted by: <jlundberg@cox.net>
Does anyone have any tips on putting a push-to-talk switch on the yoke of my Cherokee
Six? Also where can I buy aircraft grade coiled microphone cord that I
can use between the switch and the jack?
John
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