---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Wed 02/20/08: 9 ---------------------------------------------------------- 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 _____________________________________ Time: 06:51:52 AM PST US Subject: Yak-List: Re: Congrats From: "Craig Winkelmann, CFI" 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 _____________________________________ Time: 07:06:43 AM PST US Subject: Yak-List: Re: Alternator vs Generator and Overvoltage From: "Craig Winkelmann, CFI" 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 _____________________________________ Time: 08:23:18 AM PST US From: Brian Lloyd Subject: Re: Yak-List: 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 _____________________________________ Time: 10:33:07 AM PST US From: "Craig Payne" Subject: Yak-List: 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 _____________________________________ Time: 12:06:30 PM PST US From: "Jerry Painter" Subject: Yak-List: 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 _____________________________________ Time: 12:51:59 PM PST US From: ByronMFox@AOL.COM Subject: Yak-List: =?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 _____________________________________ Time: 02:56:19 PM PST US Subject: Yak-List: WARNING, DO NOT READ! It's a Mark & Brian discussion! From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" 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 _____________________________________ Time: 07:50:06 PM PST US From: Walter Lannon Subject: Re: Yak-List: 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" Sent: Wednesday, February 20, 2008 2:50 PM Subject: Yak-List: WARNING, DO NOT READ! It's a Mark & Brian discussion! > MALS-14 64E" > > 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 9 _____________________________________ Time: 09:14:04 PM PST US From: Brian Lloyd Subject: Re: Yak-List: 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. 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 . . . 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