Today's Message Index:
----------------------
1. 06:51 AM - Re: Congrats (Craig Winkelmann, CFI)
2. 07:06 AM - Re: Alternator vs Generator and Overvoltage (Craig Winkelmann, CFI)
3. 08:23 AM - Re: Re: Alternator vs Generator and Overvoltage (Brian Lloyd)
4. 10:33 AM - Pre-Oshkosh Practice (Craig Payne)
5. 12:06 PM - CJ generator systems (Jerry Painter)
6. 12:51 PM - =?ISO-8859-1?Q?- Origin of Pilot's checklist? (ByronMFox@AOL.COM)
7. 02:56 PM - WARNING, DO NOT READ! It's a Mark & Brian discussion! (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
8. 07:50 PM - Re: WARNING, DO NOT READ! It's a Mark & Brian discussion! (Walter Lannon)
9. 09:14 PM - Re: WARNING, DO NOT READ! It's a Mark & Brian discussion! (Brian Lloyd)
Message 1
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I saw Pappy's Command Wings recognition in the issue prior to this one. He was
listed with a bunch of guys who have earned awards. Great job Jim!!
Craig
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=165194#165194
Message 2
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| Subject: | Re: Alternator vs Generator and Overvoltage |
Brian:
Instead of saying:
Thanks so much for sharing your technical expertise. Now, I gotta
go find the overvoltage regulator for my CJ!!
I should have said:
Now I'll go call Bob at aereoelectric.com and find out more about the overvoltage
device you designed.
Craig
By the way, there is a unit made by Zeftronics that may work. Don't know how much
it is. But it was designed for 50 Amp Delco Remy generator. Has 3 amp max
field current, regulates 28.4 v +/- 0.4 and does overvoltage protection at 32
volts +/- 0.8 volts. Provides reverse current protection, current limiter,
overvoltate protection, under and overvoltage sensing, and has electronic controlled
generator build-up circuitry. Unit is part number G2XXPN and can be found
at zeftronics.com. Sounds expensive!!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=165202#165202
Message 3
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| Subject: | Re: Alternator vs Generator and Overvoltage |
> By the way, there is a unit made by Zeftronics that may work. Don't
> know how much it is. But it was designed for 50 Amp Delco Remy
> generator. Has 3 amp max field current, regulates 28.4 v +/- 0.4
> and does overvoltage protection at 32 volts +/- 0.8 volts. Provides
> reverse current protection, current limiter, overvoltate protection,
> under and overvoltage sensing, and has electronic controlled
> generator build-up circuitry. Unit is part number G2XXPN and can be
> found at zeftronics.com. Sounds expensive!!
It is and I am not sure you can still get them. Regardless, it is a
complete generator control system. You could use it to replace the VR
in the CJ and get all the benefits. OTOH, if you have gone that far
you may want to just switch to an alternator and get rid so some of
the weight and wiring.
Brian Lloyd
Granite Bay Montessori School 9330 Sierra College Bl
brian AT gbmontessori DOT com Roseville, CA 95661
+1.916.367.2131 (voice) +1.791.912.8170 (fax)
PGP key ID: 12095C52A32A1B6C
PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C
Message 4
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| Subject: | Pre-Oshkosh Practice |
Practice for Oshkosh 2008 will be held at West Bend, WI, starting on Thursday, July 24th for those needing to knock the rust off and ending in a mass flyout on Monday the 28th as part of the Warbird Arrival. Here are the lodging details but I need everyone who planning to attend to register on the www.flyredstar.org for head count, as in how many people to haul around, how many lunches, dinners, airplanes needing fuel and tiedowns, etc.
Of course, you can you provide your own avgas, ramp parking, local transportation,
and meals; just let me know please!
Accomodations:
A block of rooms has been reserved at the West Bend American Inn.
Please call 262-334-0307 to reserve your room, and make sure to mention you're
part of the RedStar Pilots Association. All rooms are priced at $74.90 plus tax.
Please note: Do NOT call the 800 booking number as the system will show all rooms
blocked for that date.
Fees:
An event fee will be charged to cover costs of on-field meals and transportation
(amount TBD) but no training fees will be charged. Additionally, no rooms will
be provided for IP's or Check Pilots. Individual check rides should be arranged
in advance as the focus of this event is practice for Oshkosh.
Craig Payne
cpayne@joimail.com
Message 5
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| Subject: | CJ generator systems |
One more thing to worry about with the stock generator system: Early CJ'
s
use a standard mechanical VR like a car, later models have a solid state
VR.
The solid state regulator is very susceptible to voltage spikes. Cycle
the
system and you'll burn out the internals, guaranteed. Moral: NEVER NEVE
R
NEVER cycle the electrical system in your CJ unless you are absolutely,
positively CERTAIN it has the earlier mechanical regulator.
Jerry Painter
chief pilot, CFI, A&P, airport bum,
permanent latrine orderly &c.
Wild Blue Aviation
Arlington Municipal Airport (KAWO)
Hangar A-6
19203 59th Dr. NE
Arlington, WA 98223
425-876-0865
JP@FlyWBA.com
http://www.FlyWBA.com
Message 6
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| Subject: | =?ISO-8859-1?Q?- Origin of Pilot's checklist? |
Interesting piece of aviation history.
On October 30, 1935, at Wright Air Field in Dayton, Ohio, the U.S. Army Air
Corps held a flight competition for airplane manufacturers vying to build it
s
next-generation long-range bomber. It wasn't supposed to be much of a
competition. In early evaluations, the Boeing Corporation's gleaming aluminu
m-alloy
Model 299 had trounced the designs of Martin and Douglas. Boeing's plane cou
ld
carry five times as many bombs as the Army had requested; it could fly faste
r
than previous bombers, and almost twice as far. A Seattle newspaperman who h
ad
glimpsed the plane called it the "flying fortress," and the name stuck. The
flight "competition," according to the military historian Phillip Meilinger,
was
regarded as a mere formality. The Army planned to order at least sixty-five
of
the aircraft.
A small crowd of Army brass and manufacturing executives watched as the Mode
l
299 test plane taxied onto the runway. It was sleek and impressive, with a
hundred-and-three-foot wingspan and four engines jutting out from the wings,
rather than the usual two. The plane roared down the tarmac, lifted off smoo
thly,
and climbed sharply to three hundred feet. Then it stalled, turned on one
wing, and crashed in a fiery explosion. Two of the five crew members died,
including the pilot, Major Ployer P. Hill. (re. Hill AFB, Ogden, UT)
An investigation revealed that nothing mechanical had gone wrong. The crash
had been due to "pilot error," the report said. Substantially more complex t
han
previous aircraft, the new plane required the pilot to attend to the four
engines, a retractable landing gear, new wing flaps, electric trim tabs that
needed adjustment to maintain control at different airspeeds, and constant-s
peed
propellers whose pitch had to be regulated with hydraulic controls, among ot
her
features. While doing all this, Hill had forgotten to release a new locking
mechanism on the elevator and rudder controls. The Boeing model was deemed,
as
a newspaper put it, "too much airplane for one man to fly." The Army Air Cor
ps
declared Douglas's smaller design the winner. Boeing nearly went bankrupt.
Still, the Army purchased a few aircraft from Boeing as test planes, and som
e
insiders remained convinced that the aircraft was flyable. So a group of tes
t
pilots got together and considered what to do.
They could have required Model 299 pilots to undergo more training. But it
was hard to imagine having more experience and expertise than Major Hill, wh
o
had been the U.S. Army Air Corps' chief of flight testing. Instead, they cam
e up
with an ingeniously simple approach: they created a pilot's checklist, with
step-by-step checks for takeoff, flight, landing, and taxiing. Its mere
existence indicated how far aeronautics had advanced. In the early years of
flight,
getting an aircraft into the air might have been nerve-racking, but it was
hardly complex. Using a checklist for takeoff would no more have occurred to
a
pilot than to a driver backing a car out of the garage. But this new plane w
as
too complicated to be left to the memory of any pilot, however expert.
With the checklist in hand, the pilots went on to fly the Model 299 a total
of 1.8 million miles without one accident. The Army ultimately ordered almos
t
thirteen thousand of the aircraft, which it dubbed the B-17. And, because
flying the behemoth was now possible, the Army gained a decisive air advanta
ge in
the Second World War which enabled its devastating bombing campaign across N
azi
Germany.
=C2-
=C2-
**************
Ideas to please picky eaters. Watch video on AOL Living.
(http://living.aol.com/video/how-to-please-your-picky-eater/rachel-campos-du
ffy/
2050827?NCID=aolcmp00300000002598)
Message 7
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| Subject: | WARNING, DO NOT READ! It's a Mark & Brian discussion! |
The subject was written to warn the people that get bored from reading
"Mark and Brian" discussions. Now you can't say you were not warned!
If you went this far, .. Be advised that this is a discussion on
Alternators and Generators. More of the same. Interesting to few but
the very dedicated electronic types.
Ok Brian... I'm going to take some pot shots here, and the YAK readers
will take it in the shorts from boredom I am sure! :-)
Double >>'s from me.
Single >'s from Brian.
No >'s, this reply.
>> P.s. Another little tidbit between Alternators and Generators.
>>
>> 1. If your batteries ever go totally dead in the air or on the
>> ground... I mean zero or really LOW battery voltage.... And the
>> alternator is not already on-line... It will never turn on.
>Not entirely true. Self-exciting alternators will.
>Even a regular alternator will come on line if you can get all the
>loads off the bus first.
True. Now name a light civil aircraft with a self-exciting alternator
installed. The small B&C PMG "Alternator" will in fact do that. It
also has no field input winding as you know. It uses permanent magnets.
Yes, the "Alternators" on the EA-6B Prowler have a PMG winding as well
that is then used to excite the main field. These are indeed
self-exciting and it is agreed that such models exist. These are 3
phase 30 KVA models by the way. And yes, I have 38 years experience
working with self exciting alternators, (HANDS ON Brian) but I have yet
to see one on a Cessna. If the readers of this list want to discuss the
power generating systems on a 747, then heck yes! However, sorry... not
on the YAK LIST and not on the Chevy in your garage either.
As far as a "regular" alternator coming on line with all loads
removed..... I'd like to see it done please. I went out to my 68 Camaro
and tried it. It did not work. I went out to a Cessna 180 (1974 model)
and it did not work. Then a 182, then a Piper 140, then a YAK-52TW. No
cheese. I suspect that what you are suggesting is connecting a wire
jumper directly from the output to the field. Impossible to do
in-flight, and not a bright thing to do on the ground. If I am wrong
here, please correct me. Never-the-less, I tried exactly that and it
failed to work.
So yes, again with respect, your point in theory is entirely valid.
However, I do not consider it to be Germaine unless you can point to
exactly which make and model of aircraft, or even automobile that you
actually made it work on.
>> It needs a little juice to get it going so to speak.
>That is true. OTOH the reason that the generator comes on-line without
the battery is the residual
>magnetism in the field.
I concur, and a generator does not come from the factory that way. It
has to be "FLASHED" in order to start working the very first time.
Agreed, some manufactures' did that for you back in the day. Depending
on how long it "sat" it sometimes still needed it upon installation.
>The alternator has the same thing.
Define what you mean by the "same thing". An alternator NEVER needs to
be "flashed" coming out of the box. It does NOT rely on self-induced
magnetism, and it is not a design FEATURE.... Except.... On very special
models usually found on commercial or military aircraft designed for the
express purpose of running WITHOUT any kind of battery at all.
>You can see this by disconnecting the 'B' lead, putting a voltmeter on
it, and spinning up the alternator.
>You will get some output. It should be enough to excite the field to
bootstrap the alternator to full
>output as long as nothing else is using that output. As I said, that is
how a self-exciting alternator
>gets going. And most internally-regulated alternators are self
exciting.
Interesting theory. How much does that meter load the output do you
think? Yes, I am sure you can get some voltage on a meter. In my recent
experience, not enough current to get the field excited though. It did
not work on any test I ran. As you pointed out, there are a lot of "1
wire" alternators out there. I have one on my 68 Camaro... A 100 amp
alternator. It does NOT self-excite. Period.
>But there is another issue. Neither a generator system nor an
alternator system should
>be operated without a battery in the circuit.
I assume we have now jumped back to common general aviation aircraft,
because only a very few modern tactical military aircraft have ANY kind
of battery even installed! Granted some do have APU's. However, take
the whole A-6 product line for example. No battery except for
activating a spin assist circuit, and their alternators run the whole
aircraft without a problem....no batteries needed.
This is an example of "reverse nit-picking" and I admit it. Point is,
some systems were designed to be operated with a battery and some
without. Some alternators can self excite, most can not. Discussions
then need to stay targeted on one thing at a time.
ANYWAY....Yes, I agree.... On models designed to run with a battery it
is true that it is inadvisable to run the system without one. Unless
maybe your life is at stake. Say, IFR at night. Or, as a young Marine
trying to get back to the base after his battery had been stolen out of
his car and no money to buy a new one, and too honest to swipe someone
else's. A 12 volt lantern battery WILL excite a car alternator enough
to get it going. Been there, done that, have the tea-shirt. Drove 500
miles back to the base exactly that way.
>The battery is needed to stabilize the voltage. Without it you have
nothing to absorb the
>excess output when you load-dump. Neither an alternator nor a generator
can change its
>output suddenly. It takes time for the magnetism in the field to ramp
up or ramp down
>with a field current change. (Current lags voltage in an inductor if
you want to get technical.)
Yes... I am familiar with AC theory Brian... And yes I remember ELI the
ICE man. But... You kind of make it sound like without the battery,
everything will self-destruct.
>That means that, without a battery, turn off the landing light and
watch the alternator or
>generator create an over voltage event.
Better yet, leave it on and watch it tend to smooth out voltage
excursions. :-)
That said, I went out to my YAK-50 last night and disconnected the
battery. I then started it. I then ran up the engine to about 50 % and
called the tower and flew it around the pattern with no battery
connected. Nothing burnt out. Everything worked fine. It was not much
of a risk really. On a flight a few years ago I blew the battery fuse
in flight. Well... Actually the fuse holder fell apart... But same
thing. I never even knew it until I idled the engine down and
everything in the cockpit went dead.
This morning I went out to my old piece of junk Renault Alliance. I
started the car. I then rev'ed the engine up to 2000 RPM and
disconnected the battery. It took two people to pull this stunt off. I
then drove it around the block. Nothing bad happened. Of course I did
not have a $10,000 Avionics Stack fired up either.
>Now we have said WAY more about alternators and generators than anyone
else wanted to hear. ;-)
Probably so.
Mark Bitterlich
P.s. Here is my opinion, and I have tried it. If you are flying around
and suspect you have a bad battery, DO NOT TURN OFF THE ALTERNATOR to
check your battery voltage, it very well might not come back on with
zero, or even near zero battery voltage. It is also entirely possible
that the aircraft will be subject to inductive voltage kicks from
operating that alternator without a battery (as Brian pointed out).
These might even be high enough to cause equipment damage under the
right conditions. As the pilot in command, you'll have to make the
decision which possibility is worse for you. However, my testing
confirms that if you turn off the alternator with a dead battery,
turning it back on will accomplish nothing unless you are lucky enough
to have just a little something left in the battery to excite the
alternator allowing it to get back on line.
Next, regardless of alternator OR generator, if either is on-line and
you have a bad battery, the power you DO generate will power the landing
gear motor, will run all your lights, and HOPEFULLY will not damage your
avionics. Given the tests I just ran in my aircraft, I would not
hesitate to do it. And yes, the tower reported bad hum in my
transmissions. However my little Apollo 360 GPS hung in there without a
hick-up.
P.p.s. And Brian, I am not saying you are WRONG in any way. I am
saying that it is easy to switch back and forth between discussing
apples and oranges during any kind of electronic discourse of this
nature. Apples remain apples and oranges remain orange. However, when
you put them in the same bowl, we need to be careful not to act like
they are the same fruit. My 2 cents anyway.
Message 8
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| Subject: | Re: WARNING, DO NOT READ! It's a Mark & Brian discussion! |
Well, I for one do not get bored reading "Mark and Brian" discussions. You
both know much more than I do on this subject and I have been restoring and
maintaining Warbird types for at least 40 years.
Probably because I'm too old to know any better I have nothing but positive
things to say about the Bendix Eclipse generator, carbon pile regulator and
control units used in these aircraft.
There are questions I would like to put to you but since these are specific
to the above systems I would bore everyone else so will pass.
Keep up the good work.
Cheers;
Walt
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
Sent: Wednesday, February 20, 2008 2:50 PM
Subject: Yak-List: WARNING, DO NOT READ! It's a Mark & Brian discussion!
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> The subject was written to warn the people that get bored from reading
> "Mark and Brian" discussions. Now you can't say you were not warned!
>
> If you went this far, .. Be advised that this is a discussion on
> Alternators and Generators. More of the same. Interesting to few but
> the very dedicated electronic types.
>
>
> Ok Brian... I'm going to take some pot shots here, and the YAK readers
> will take it in the shorts from boredom I am sure! :-)
>
> Double >>'s from me.
> Single >'s from Brian.
> No >'s, this reply.
>
>
>>> P.s. Another little tidbit between Alternators and Generators.
>>>
>>> 1. If your batteries ever go totally dead in the air or on the
>>> ground... I mean zero or really LOW battery voltage.... And the
>>> alternator is not already on-line... It will never turn on.
>
>>Not entirely true. Self-exciting alternators will.
>>Even a regular alternator will come on line if you can get all the
>>loads off the bus first.
>
> True. Now name a light civil aircraft with a self-exciting alternator
> installed. The small B&C PMG "Alternator" will in fact do that. It
> also has no field input winding as you know. It uses permanent magnets.
> Yes, the "Alternators" on the EA-6B Prowler have a PMG winding as well
> that is then used to excite the main field. These are indeed
> self-exciting and it is agreed that such models exist. These are 3
> phase 30 KVA models by the way. And yes, I have 38 years experience
> working with self exciting alternators, (HANDS ON Brian) but I have yet
> to see one on a Cessna. If the readers of this list want to discuss the
> power generating systems on a 747, then heck yes! However, sorry... not
> on the YAK LIST and not on the Chevy in your garage either.
>
> As far as a "regular" alternator coming on line with all loads
> removed..... I'd like to see it done please. I went out to my 68 Camaro
> and tried it. It did not work. I went out to a Cessna 180 (1974 model)
> and it did not work. Then a 182, then a Piper 140, then a YAK-52TW. No
> cheese. I suspect that what you are suggesting is connecting a wire
> jumper directly from the output to the field. Impossible to do
> in-flight, and not a bright thing to do on the ground. If I am wrong
> here, please correct me. Never-the-less, I tried exactly that and it
> failed to work.
>
> So yes, again with respect, your point in theory is entirely valid.
> However, I do not consider it to be Germaine unless you can point to
> exactly which make and model of aircraft, or even automobile that you
> actually made it work on.
>
>>> It needs a little juice to get it going so to speak.
>
>>That is true. OTOH the reason that the generator comes on-line without
> the battery is the residual
>>magnetism in the field.
>
> I concur, and a generator does not come from the factory that way. It
> has to be "FLASHED" in order to start working the very first time.
> Agreed, some manufactures' did that for you back in the day. Depending
> on how long it "sat" it sometimes still needed it upon installation.
>
>>The alternator has the same thing.
>
> Define what you mean by the "same thing". An alternator NEVER needs to
> be "flashed" coming out of the box. It does NOT rely on self-induced
> magnetism, and it is not a design FEATURE.... Except.... On very special
> models usually found on commercial or military aircraft designed for the
> express purpose of running WITHOUT any kind of battery at all.
>
>>You can see this by disconnecting the 'B' lead, putting a voltmeter on
> it, and spinning up the alternator.
>>You will get some output. It should be enough to excite the field to
> bootstrap the alternator to full
>>output as long as nothing else is using that output. As I said, that is
> how a self-exciting alternator
>>gets going. And most internally-regulated alternators are self
> exciting.
>
> Interesting theory. How much does that meter load the output do you
> think? Yes, I am sure you can get some voltage on a meter. In my recent
> experience, not enough current to get the field excited though. It did
> not work on any test I ran. As you pointed out, there are a lot of "1
> wire" alternators out there. I have one on my 68 Camaro... A 100 amp
> alternator. It does NOT self-excite. Period.
>
>>But there is another issue. Neither a generator system nor an
> alternator system should
>>be operated without a battery in the circuit.
>
> I assume we have now jumped back to common general aviation aircraft,
> because only a very few modern tactical military aircraft have ANY kind
> of battery even installed! Granted some do have APU's. However, take
> the whole A-6 product line for example. No battery except for
> activating a spin assist circuit, and their alternators run the whole
> aircraft without a problem....no batteries needed.
>
> This is an example of "reverse nit-picking" and I admit it. Point is,
> some systems were designed to be operated with a battery and some
> without. Some alternators can self excite, most can not. Discussions
> then need to stay targeted on one thing at a time.
>
> ANYWAY....Yes, I agree.... On models designed to run with a battery it
> is true that it is inadvisable to run the system without one. Unless
> maybe your life is at stake. Say, IFR at night. Or, as a young Marine
> trying to get back to the base after his battery had been stolen out of
> his car and no money to buy a new one, and too honest to swipe someone
> else's. A 12 volt lantern battery WILL excite a car alternator enough
> to get it going. Been there, done that, have the tea-shirt. Drove 500
> miles back to the base exactly that way.
>
>>The battery is needed to stabilize the voltage. Without it you have
> nothing to absorb the
>>excess output when you load-dump. Neither an alternator nor a generator
> can change its
>>output suddenly. It takes time for the magnetism in the field to ramp
> up or ramp down
>>with a field current change. (Current lags voltage in an inductor if
> you want to get technical.)
>
> Yes... I am familiar with AC theory Brian... And yes I remember ELI the
> ICE man. But... You kind of make it sound like without the battery,
> everything will self-destruct.
>
>>That means that, without a battery, turn off the landing light and
> watch the alternator or
>>generator create an over voltage event.
>
> Better yet, leave it on and watch it tend to smooth out voltage
> excursions. :-)
>
> That said, I went out to my YAK-50 last night and disconnected the
> battery. I then started it. I then ran up the engine to about 50 % and
> called the tower and flew it around the pattern with no battery
> connected. Nothing burnt out. Everything worked fine. It was not much
> of a risk really. On a flight a few years ago I blew the battery fuse
> in flight. Well... Actually the fuse holder fell apart... But same
> thing. I never even knew it until I idled the engine down and
> everything in the cockpit went dead.
>
> This morning I went out to my old piece of junk Renault Alliance. I
> started the car. I then rev'ed the engine up to 2000 RPM and
> disconnected the battery. It took two people to pull this stunt off. I
> then drove it around the block. Nothing bad happened. Of course I did
> not have a $10,000 Avionics Stack fired up either.
>
>>Now we have said WAY more about alternators and generators than anyone
> else wanted to hear. ;-)
>
> Probably so.
>
> Mark Bitterlich
>
> P.s. Here is my opinion, and I have tried it. If you are flying around
> and suspect you have a bad battery, DO NOT TURN OFF THE ALTERNATOR to
> check your battery voltage, it very well might not come back on with
> zero, or even near zero battery voltage. It is also entirely possible
> that the aircraft will be subject to inductive voltage kicks from
> operating that alternator without a battery (as Brian pointed out).
> These might even be high enough to cause equipment damage under the
> right conditions. As the pilot in command, you'll have to make the
> decision which possibility is worse for you. However, my testing
> confirms that if you turn off the alternator with a dead battery,
> turning it back on will accomplish nothing unless you are lucky enough
> to have just a little something left in the battery to excite the
> alternator allowing it to get back on line.
>
> Next, regardless of alternator OR generator, if either is on-line and
> you have a bad battery, the power you DO generate will power the landing
> gear motor, will run all your lights, and HOPEFULLY will not damage your
> avionics. Given the tests I just ran in my aircraft, I would not
> hesitate to do it. And yes, the tower reported bad hum in my
> transmissions. However my little Apollo 360 GPS hung in there without a
> hick-up.
>
> P.p.s. And Brian, I am not saying you are WRONG in any way. I am
> saying that it is easy to switch back and forth between discussing
> apples and oranges during any kind of electronic discourse of this
> nature. Apples remain apples and oranges remain orange. However, when
> you put them in the same bowl, we need to be careful not to act like
> they are the same fruit. My 2 cents anyway.
>
>
>
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| Subject: | Re: WARNING, DO NOT READ! It's a Mark & Brian discussion! |
>> Not entirely true. Self-exciting alternators will.
>> Even a regular alternator will come on line if you can get all the
>> loads off the bus first.
>
> True. Now name a light civil aircraft with a self-exciting
> alternator
> installed.
Well, my CJ "Betty" did. Still does I am pretty sure. It is why you
have to get the RPM up to about 2000 before the alternator comes on-
line. After that it is fine even at idle until you shut it down.
> As far as a "regular" alternator coming on line with all loads
> removed..... I'd like to see it done please.
If you have an internally-regulated alternator with the internal VR
powered from a diode trio from the stator, your alternator will self-
excite. Every IR alternator so wired I have tried did self-excite. I
have done this with GM Delco, Ford Autolite, and Motorola.
> I went out to my 68 Camaro
> and tried it. It did not work. I went out to a Cessna 180 (1974
> model)
> and it did not work. Then a 182, then a Piper 140, then a YAK-52TW. No
> cheese. I suspect that what you are suggesting is connecting a wire
> jumper directly from the output to the field.
No.
> I concur, and a generator does not come from the factory that way. It
> has to be "FLASHED" in order to start working the very first time.
> Agreed, some manufactures' did that for you back in the day.
> Depending
> on how long it "sat" it sometimes still needed it upon installation.
Yes.
>> The alternator has the same thing.
>
> Define what you mean by the "same thing". An alternator NEVER needs
> to
> be "flashed" coming out of the box. It does NOT rely on self-induced
> magnetism, and it is not a design FEATURE.... Except.... On very
> special
> models usually found on commercial or military aircraft designed for
> the
> express purpose of running WITHOUT any kind of battery at all.
As with all steel armature pole pieces, if you apply a magnetic field
for a long period of time it will become at least partially magnetized
permanently. The residual magnetism in the armature will induce
voltage in the stator. That voltage may be (probably is) less than
battery voltage so you would never see enough output to charge the
battery. But it is enough to turn on the internal VR which will then
shunt the small available current into the field. This will increase
the output which then increases the current in the field. This
positive feedback process continues until the unit is fully on-line.
So I find your negative results very surprising. Every internally-
regulated alternator I have used that is self-powered through the
diode trio connected to the stator (independent of the normal diode
bridge that feeds output to the B lead) has been self-exciting in the
manner I have described.
>> gets going. And most internally-regulated alternators are self
> exciting.
>
> Interesting theory.
'Taint theory.
> How much does that meter load the output do you
> think?
Nothing to speak of. If you you are looking at the B-lead you are
getting two diode drops, not 1. That makes things worse. The diode
trio works with a single diode drop hence you have almost an extra
volt available from the feeble output of the stator from the residual
magnetism in the rotor.
> Yes, I am sure you can get some voltage on a meter. In my recent
> experience, not enough current to get the field excited though.
Tap the diode trio.
> It did
> not work on any test I ran. As you pointed out, there are a lot of "1
> wire" alternators out there. I have one on my 68 Camaro... A 100 amp
> alternator. It does NOT self-excite. Period.
I am surprised. You have just told me about the first one that did not
self-excite that I have heard of. Remember, a "1-wire" alternator has
to self excite or it must get some power from the battery. Actually
most alternators get a tiny current from teh battery through the idiot-
light circuit. The 100mA or so needed to light that lamp is more than
enough to turn on the internal VR and the field even at idle. But if
you disconnect the idiot light circuit the alternator has to self-
excite. It will.
>> But there is another issue. Neither a generator system nor an
> alternator system should
>> be operated without a battery in the circuit.
>
> I assume we have now jumped back to common general aviation aircraft,
> because only a very few modern tactical military aircraft have ANY
> kind
> of battery even installed!
Yes, I am talking about GA aircraft. Hell, I am talking about most
aircraft. And no, I am not talking about current military aircraft
with electrical systems designed not to need a battery. This whole
discussion started with alternators and generators on Yak/CJ aircraft
and that is where I thought we were. It is certainly possible to
construct an alternator controller and output clamping system that
will prevent a load-dump incident but the standard alternator (or
generator) that is used in a run-of-the-mill automobile or GA aircraft
doesn't have that.
> Granted some do have APU's. However, take
> the whole A-6 product line for example. No battery except for
> activating a spin assist circuit, and their alternators run the whole
> aircraft without a problem....no batteries needed.
>
> This is an example of "reverse nit-picking" and I admit it.
Keine sheiss, meine Herr. I was talking about electrical systems in
the aircraft we own, not necessarily the ones some of us are paid to
fly into harm's way.
> Point is,
> some systems were designed to be operated with a battery and some
> without. Some alternators can self excite, most can not. Discussions
> then need to stay targeted on one thing at a time.
>
> ANYWAY....Yes, I agree.... On models designed to run with a battery it
> is true that it is inadvisable to run the system without one. Unless
> maybe your life is at stake. Say, IFR at night. Or, as a young
> Marine
> trying to get back to the base after his battery had been stolen out
> of
> his car and no money to buy a new one, and too honest to swipe someone
> else's. A 12 volt lantern battery WILL excite a car alternator enough
> to get it going. Been there, done that, have the tea-shirt. Drove 500
> miles back to the base exactly that way.
Sure, you can do it. If your loads remain relatively constant
everything will work out fine without a battery. Even a honkin' big
capacitor will do the trick. But if you take the battery out of the
circuit, leave the alternator on, bring up the load with lights, pitot
heat, butt-warmer, etc., and then turn off some large load, the output
of the alternator will go a lot higher than you want for a short
period of time. This is called a load-dump incident and you need
something to absorb the extra output.
But even some spam-can electrical systems can run without a battery. I
believe some of the Beechcraft are designed to run from their
alternators without the battery on-line. It all depends on how you
design the system.
But as a rule of thumb, running your electrical system in your car or
GA aircraft (or CJ or Yak) without the battery on-line, you are asking
for problems. Maybe not this time or the next but if you keep doing
it, it will bite you in the butt some day.
>
>
>> The battery is needed to stabilize the voltage. Without it you have
> nothing to absorb the
>> excess output when you load-dump. Neither an alternator nor a
>> generator
> can change its
>> output suddenly. It takes time for the magnetism in the field to ramp
> up or ramp down
>> with a field current change. (Current lags voltage in an inductor if
> you want to get technical.)
>
> Yes... I am familiar with AC theory Brian... And yes I remember ELI
> the
> ICE man. But... You kind of make it sound like without the battery,
> everything will self-destruct.
No, I am saying that without the battery to provide a load for the
momentary overvoltage situation caused by load-dump, you will get a
big spike, the energy content of which is a function of the inductance
of the field.
Most solid-state regulators for alternators and generators use a
series pass transistor which switches on and off to pulse-width
modulate the field current. (I will be happy to draw you a schematic
but you can imagine a comparitor driving the base of the switch
transistor, turning the transistor on when the voltage is below the
setpoint and off when it is above.) The problem is that when the
transistor switches off, the back EMF from the field is high enough to
damage the switch transistor. So they put in a clamp diode to protect
the transistor. The problem here is that the clamp diode allows the
back EMF a low-impedance path to ground keeping current flowing in the
field. This slows down the collapse of the field. This tends to hold
the output of the alternator high for some number of milliseconds
longer than you expect.
So imagine the situation now. You have a lot of loads on. The
alternator is working its little butt off. The field current is pretty
high. Suddenly you turn off the load. The bus voltage starts to rise.
The VR shuts off the field but the collapsing B-field from the
armature induces a big back-EMF. The clamp diode shunts the current
from the back-EMF to ground which holds up the B-field. The output of
the alternator continues to rise even tho' the VR has done the right
thing and it is no longer sourcing field current. This goes on until
the B-field collapses. This may take 10's or 100's of milliseconds. At
that point the output of the alternator drops. If the battery is
there, it absorbs the extra energy and the voltage on the bus moves
only a little. If there is no device to absorb that extra energy, e.g.
battery, capacitor, transorb, clamping zener, dedicated clamp circuit,
etc., you will see a big spike. If there is enough energy in that
spike it can damage the power supplies in your avionics.
Load dump is real.
>> That means that, without a battery, turn off the landing light and
> watch the alternator or
>> generator create an over voltage event.
>
> Better yet, leave it on and watch it tend to smooth out voltage
> excursions. :-)
>
> That said, I went out to my YAK-50 last night and disconnected the
> battery. I then started it. I then ran up the engine to about 50 %
> and
> called the tower and flew it around the pattern with no battery
> connected. Nothing burnt out. Everything worked fine.
Doesn't your Yak-50 use a B&C PM alternator? They work differently and
they will not exhibit load-dump effect. You need an alternator or
generator with a field circuit. Also, the larger the alternator, the
more profound the effect. You might see load-dump effect with a small
field-circuit alternator but you will find that the energy in the
spike is not enough to be a problem.
Hell, I would expect a PM alternator (dynamo) to run just fine without
a battery.
But lets say you are still running the stock generator. I would not
expect a load-dump event in your Yak-50. You aren't switching big
loads off. You don't have anything like a landing-gear motor. Repeat
your experiment, this time with the landing light and pitot-heat on.
Turn them both off at the same time. I betcha you get a GOOD spike.
> It was not much
> of a risk really. On a flight a few years ago I blew the battery fuse
> in flight. Well... Actually the fuse holder fell apart... But same
> thing. I never even knew it until I idled the engine down and
> everything in the cockpit went dead.
>
> This morning I went out to my old piece of junk Renault Alliance. I
> started the car. I then rev'ed the engine up to 2000 RPM and
> disconnected the battery. It took two people to pull this stunt
> off. I
> then drove it around the block. Nothing bad happened. Of course I
> did
> not have a $10,000 Avionics Stack fired up either.
And you probably did not create a load-dump. That is where the problem
arises. Do that again and remove a big load, e.g. turn off the
headlights. Put a 'scope on the bus. It will make a believer out of you.
Mark, I like you. You are one of the few people in this world I have
discussions like this with. But in this case, for better or for worse,
I am right about this. Go look up "load dump". Oh, and I stand by the
self-exciting alternator too. ;-)
> P.s. Here is my opinion, and I have tried it. If you are flying
> around
> and suspect you have a bad battery, DO NOT TURN OFF THE ALTERNATOR to
> check your battery voltage, it very well might not come back on with
> zero, or even near zero battery voltage. It is also entirely possible
> that the aircraft will be subject to inductive voltage kicks from
> operating that alternator without a battery (as Brian pointed out).
> These might even be high enough to cause equipment damage under the
> right conditions. As the pilot in command, you'll have to make the
> decision which possibility is worse for you. However, my testing
> confirms that if you turn off the alternator with a dead battery,
> turning it back on will accomplish nothing unless you are lucky enough
> to have just a little something left in the battery to excite the
> alternator allowing it to get back on line.
For externally-regulated alternators, this is 100% true. This means
almost all aircraft.
> Next, regardless of alternator OR generator, if either is on-line and
> you have a bad battery, the power you DO generate will power the
> landing
> gear motor, will run all your lights, and HOPEFULLY will not damage
> your
> avionics.
Ah, landing gear. When the gear is finally down and the gear motor
shuts off, look for one mutha' big-ass load-dump event. The dump it
takes may be in your $20,000 glass PFD. ;-)
> Given the tests I just ran in my aircraft, I would not
> hesitate to do it. And yes, the tower reported bad hum in my
> transmissions. However my little Apollo 360 GPS hung in there
> without a
> hick-up.
>
> P.p.s. And Brian, I am not saying you are WRONG in any way.
Ah, good. Because I *am* right.
> I am
> saying that it is easy to switch back and forth between discussing
> apples and oranges during any kind of electronic discourse of this
> nature. Apples remain apples and oranges remain orange. However,
> when
> you put them in the same bowl, we need to be careful not to act like
> they are the same fruit. My 2 cents anyway.
<sigh> And here I thought *I* was the most anal-retentive, pedantic
asshole on this list!
(Love ya' Mark. :-)
--
Brian Lloyd 3191 Western Drive
brian HYPHEN 1927 AT lloyd DOT com Cameron Park, CA 95682
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
PGP key ID: 12095C52A32A1B6C
PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C
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