---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Tue 04/28/15: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:02 AM - PM alternator (BobbyPaulk@comcast.net) 2. 08:38 AM - Re: Alternator (FLYaDIVE) 3. 09:24 AM - Re: Alternator (Robert L Nuckolls III) 4. 09:55 AM - Re: Alternator (Rob Turk) 5. 11:13 AM - Re: Alternator (Robert L Nuckolls III) ________________________________ Message 1 _____________________________________ Time: 07:02:06 AM PST US From: BobbyPaulk@comcast.net Subject: JabiruEngine-List: PM alternator Bob, I always thought the PM Alt was capable of more. The 6 burned coils kinda proved that - to me anyway. I was hoping the higher voltage at a lower rpm would make the R / R more efficient and I could gain a few more amps at the lower rpm. Anyway I would be interested in any new developments for a better R /R if you get into that aspect. I also subscribe to your AeroElectric list. Bobby ________________________________ Message 2 _____________________________________ Time: 08:38:37 AM PST US Subject: Re: JabiruEngine-List: Alternator From: FLYaDIVE Right you are Bob N.! Things will NOT change until many more 'builders'... Not Engineers, come to the realization that: You can't fool Mother Physics! Physics is what it is and no matter how much hoping and praying you do, you CAN'T change it! When this issue first came up years ago I posted something like: You can't get blood from a stone and why not just install a small AUTOMOTIVE alternator with built in ACU! All sorts of responses surfaced... I don't want to loose the extra HP the alternator will require. Too much weight. What do I do with the built in unit... DUH! Remove it! The only acceptable response was: I don't have room to install it - No room under the cowl. Now, here I have feeling for the poor builder. Small alternators such as the MITSUBISHI are as small a large man's hand and put out 40 to 70 Amps. Simple, easy to install, easy to diagnose, easy to regulate (built in), easy to replace if you breakdown at a remote airport... Just SIMPLY EASY! So, why kill yourself trying to get blood from a stone? And I like Jabiru Engines... I hate Rat-Tax (Rotex). Barry On Mon, Apr 27, 2015 at 6:21 PM, Robert L Nuckolls III < bob.nuckolls@aeroelectric.com> wrote: > bob.nuckolls@aeroelectric.com> > > At 15:39 2015-04-27, you wrote: > >> List >> I was getting 14.6 volts steady at 1200 and 1400 rpm while taxiing out. >> My amp meter hunts so I do not know what it was putting out ( Zero to 4 >> indicated ). After the first flight that had Icom radio, Dynon Efis, and >> the Ro-tec E mag I figured about five to seven amps with the radio not >> transmitting. The volt meter was still steady at 14.6. >> One thing I did observe was when I put the battery tender on it it only >> took about 10 minutes or less for the green light to come on. It usually >> takes 25 to 30 minutes. >> I believe the coils shorted out when I added load by turning on the >> strobes. After I removed the coils it looks like the varnish could have >> been rubbed off at the corner of the turn where the wires exit to the >> backside of the coils. I could not really tell since the wire was blackened >> and had no varnish left. >> One circuit was burned black ( all 6 coils ) while the other circuit was >> in tact. >> I knew it was a trade off by going to one series circuit in lieu of the 2 >> parallel but I was used to turning off the transponder on short final and >> the strobes after exiting the runway ( unless there was ground traffic). >> Anyway I am afixin to order the CAMit 40 ~ 45 amp alternator and adapter >> kit. That ought to fix the problem unless I have another self induced uh-oh! >> >> Thanks to all that responded ( no flames : ) >> >> bobby >> > > > Sadly, your observations on the series-connected > alternator 'experiment' were somewhat predictable. > Sorry you've had to suffer the indignities imposed > by the laws of physics. > > The PM alternator has been poorly exploited for the > best it has to offer. PM alternators are simple, long > lived, robust and not terribly inefficient. Unfortunately, > the rectifier/regulator combinations have NOT evolved > with the best that power electronics has to offer. > > We're doing the rudimentary proof of concept studies > for a PM alternator R/R that will offer greater > maximum output commensurate with the alternator's > real ability to convert mechanical motion into > electrical energy. > > The belt driven alternator is a low-risk albeit > heavier and more expensive alternative. It may indeed > be the most practical solution depending on you > use your airplane. > > But it's possible that a modern R/R configuration will > breath new life into the PM alternator concept with > increased performance and system reliability. > > We shall see .. . > > > Bob . . . > > > ----------------------------- > Bob Nuckolls > AeroElectric Connection > P.O. Box 130 > Medicine Lodge, KS 67104-0130 > Mobile: 316-209-7528 > Web: http://aeroelectric.com > ------------------------------ > > ________________________________ Message 3 _____________________________________ Time: 09:24:06 AM PST US From: Robert L Nuckolls III Subject: Re: JabiruEngine-List: Alternator At 10:37 2015-04-28, you wrote: >Right you are Bob N.! > >Things will NOT change until many more 'builders'... Not Engineers, >come to the realization that: You can't fool Mother >Physics! Physics is what it is and no matter how much hoping and >praying you do, you CAN'T change it! > >When this issue first came up years ago I posted something >like: You can't get blood from a stone and why not just install a >small AUTOMOTIVE alternator with built in ACU! All sorts of >responses surfaced... To be sure, the universe runs on physics and no matter what discipline one plies their talents, it all comes down to properties of materials and management of energy. The evolution of the PM alternator has roots on small bikes and RV's like snow-mobiles. They often mounted a "lighting coil" on the crankcase and spun a magnet close by to offer perhaps 20-30 watts of AC to light a headlamp. The ghost of F. Kettering must have been smiling down on the endeavor as individuals began to ponder ways that the headlamp intensity could be maintained over full range of engine rpm . . . not limited to full bright at open throttle. So the simple rectifier/regulator came along with a crude voltage control profile that prevented serious overcharging of the battery. Keep in mind that ALL this was before rare earth and SLVA technologies. Yeah . . . it kinda worked okay. The regulators were simple silicon controlled rectifiers that were 'fired' as a dead short across the alternator when the bus voltage got too high. Hence, the alternator was fully loaded all the time. Furhter it had to be inherently current limiting to keep it from smoking when there were no system loads and the battery was fully charged. Then came rare earth magnets. About the same time, SLVA batteries pushed their flooded ancestors into a timely and well deserved place in history. A new breed of R/R came along which formed a bridge rectifier with SCR's in two legs of the bridge for control by some rudimentary electronics. Again, not the best we knew how to do but ADEQUATE to contemporary design goals. Examples example of this now dated technology include the successes logged by Rotax, B&C (The SD-8 was B&C's first product. I was a collaborator on that development and helped them purchase the sand-castings for Electro-Mech standby generators for Bonanza's AND20000 pad drive pad). The improved alternators benefited from rare earth, So while AVAILABLE AC power from the alternator went up . . . DC power demands on the airplanes being built went up too. Sadly, the R/R did not evolve with the power electronics side of the house. There has never been anything inherently EVIL or even grossly7 inept about the participants in this saga. Each feature from alternator to R/R, to battery, to evolution of the all-electric OBAM aircraft was plotting along with each technology driven by separate marketing and business models most of which hand nothing to do with the unique electrical environment that was evolving on OBAM aircraft. As a 45+ year observer and participant in art and science of systems design and fabrication, I can offer historical narrative above and propose the next big step in the evolution of the PM alternator as a practical, engine driven power source. The efficiency of the legacy triggered-bridge rectifier is terrible. I judge that these designs not only cripple the system's ability to deliver at low rpm and may toss off 20 to 50% of total available energy as heat. The next step borrows from the energy management technologies ubiquitous in computers for decades. In the mean time, I would be cautious about bad-mouthing the PM alternator. Shortcomings in performance had little to do with design of the alternator and MUCH to do with design of the R/R. Did some development testing at B&C last week. Will probably be back there again this week. The ingredients that go into this recipe for success have existed for decades . . . it's a matter of picking the right combination . . . for properties of materials and management of energy. Bob . . . ----------------------------- Bob Nuckolls AeroElectric Connection P.O. Box 130 Medicine Lodge, KS 67104-0130 Mobile: 316-209-7528 Web: http://aeroelectric.com ------------------------------ ________________________________ Message 4 _____________________________________ Time: 09:55:56 AM PST US From: Rob Turk Subject: Re: JabiruEngine-List: Alternator You said it, Bob. Modern technology switching regulators allow for wide input and constant output with high reliability, high efficiency and low weight. On a Jabiru, a switching regulator must be designed to work with ~5:1 input range (minimum 7 volt AC @ 700rpm, maximum 35V@3300rpm.). The original windings are designed to deliver 20A, so at cruise of 2700rpm (~28V) it should deliver close to 500W of electrical power. If you'd use an efficient switcher you can get ~85-90% available, which translates to almost 30A@14.6V. Plenty for all but a flying Christmas tree. Oh, and a switching regulator would make it possible to go to a 28V system as well, saving weight on wiring. Only concern I'd have with these is RF interference, these switchers aren't particularly clean.. Rob On 4/28/2015 6:23 PM, Robert L Nuckolls III wrote: > > > ... > The next step borrows from the energy management > technologies ubiquitous in computers for decades. > In the mean time, I would be cautious about > bad-mouthing the PM alternator. Shortcomings > in performance had little to do with design > of the alternator and MUCH to do with design > of the R/R. > > Did some development testing at B&C last week. > Will probably be back there again this week. > The ingredients that go into this recipe for > success have existed for decades . . . it's > a matter of picking the right combination . . . > for properties of materials and management of > energy. > > > Bob . . . > > > ----------------------------- > Bob Nuckolls > AeroElectric Connection > P.O. Box 130 > Medicine Lodge, KS 67104-0130 > Mobile: 316-209-7528 > Web: http://aeroelectric.com > ------------------------------ > > ________________________________ Message 5 _____________________________________ Time: 11:13:30 AM PST US From: Robert L Nuckolls III Subject: Re: JabiruEngine-List: Alternator At 11:54 2015-04-28, you wrote: > >You said it, Bob. Modern technology switching regulators allow for >wide input and constant output with high reliability, high >efficiency and low weight. > >On a Jabiru, a switching regulator must be designed to work with >~5:1 input range (minimum 7 volt AC @ 700rpm, maximum 35V@3300rpm. The 5:1 range target assumes that the alternator's maximum rated ENERGY output is uniform over the range of RPM . . . which it is not. >. The original windings are designed to deliver 20A, so at cruise of >2700rpm (~28V) it should deliver close to 500W of electrical power. What gage wire is used to wind those stators? > If you'd use an efficient switcher you can get ~85-90% available, > which translates to almost 30A@14.6V. Plenty for all but a flying > Christmas tree. Oh, and a switching regulator would make it > possible to go to a 28V system as well, saving weight on wiring. Based on the present state of development studies, I would expect a pretty good boost at cruise RPM perhaps as much as 50% over present capabilities. I would also expect USEFUL output to MUCH lower rpm levels than with the current technology. But hundreds of watts at idle is not in the cards without some re-design of the alternators. That would be the next phase of system upgrades. >Only concern I'd have with these is RF interference, these switchers >aren't particularly clean.. Switchmode regulators are widely used in a host of RFI sensitive environments. There is NO design that cannot be tailored to the most critical of EMC environments. I have desktop, consumer grade computer power supplies sitting right next to amateur radio equipment capable of sniffing microvolt level signals. I'm not suggesting that there aren't occasional 'birdies' but I've yet to be plagued by any of them. Got a nice HF transceiver I'll be putting into service as soon as I can get a new antenna up . . . I'll see if I need to modify those words. In any case, there's a LOT of computers co-existing in ham radio shacks . . . it can be done. Bob . . . ----------------------------- Bob Nuckolls AeroElectric Connection P.O. Box 130 Medicine Lodge, KS 67104-0130 Mobile: 316-209-7528 Web: http://aeroelectric.com ------------------------------ ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message jabiruengine-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/JabiruEngine-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/jabiruengine-list Browse Digests http://www.matronics.com/digest/jabiruengine-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.