---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 06/30/16: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:28 AM - Re: Hypothetical Battery Contactor Failure (racerjerry) 2. 06:43 AM - Re: Hypothetical Battery Contactor Failure (user9253) 3. 07:56 AM - Re: Bendix King KY97A Tuning Problem (racerjerry) 4. 08:50 AM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III) 5. 03:20 PM - Re: Hypothetical Battery Contactor Failure (user9253) 6. 05:32 PM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III) 7. 05:35 PM - Composite Aircraft and Lightning Strikes (William Hunter) 8. 06:26 PM - Re: Re: Hypothetical Battery Contactor Failure (Charlie England) 9. 08:44 PM - Re: Composite Aircraft and Lightning Strikes (Robert L. Nuckolls, III) 10. 08:52 PM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III) 11. 09:36 PM - Re: Hypothetical Battery Contactor Failure (user9253) 12. 10:20 PM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III) 13. 11:43 PM - Re: Composite Aircraft and Lightning Strikes (Peter Pengilly) ________________________________ Message 1 _____________________________________ Time: 06:28:25 AM PST US Subject: AeroElectric-List: Re: Hypothetical Battery Contactor Failure From: "racerjerry" On a simple aircraft such as my Cessna 172K, the voltage regulator "S" terminal is supplied with power through the battery contactor. If no power is present at the voltage regulator, the alternator field SHOULD not be energized rendering the alternator inoperative. The first noticeable indication after battery voltage bleeds down is that my VHF radio display (KX-155) goes blank. In order to alert me to take necessary steps to conserve battery power after an alternator failure, I installed a "13V Idiot Light" from Perihelion Design, which I highly recommend. Only $50 and legally installed without paperwork using Velcro and powered through cigar lighter. In addition, I added a Westach 6-16 VDC voltmeter to give me a REAL indication instead of the near worthless ammeter. -------- Jerry King Read this topic online here: http://forums.matronics.com/viewtopic.php?p=457550#457550 ________________________________ Message 2 _____________________________________ Time: 06:43:29 AM PST US Subject: AeroElectric-List: Re: Hypothetical Battery Contactor Failure From: "user9253" Once an engine is running above idle, the battery no longer supplies electrical power to the aircraft. The alternator does. Many alternators will continue to operate if the battery is then disconnected. The electrical current needed to power the alternator field comes from the alternator output, whether the battery is connected or not. There may be some alternators that will not continue to run without a battery connected. Even for alternators that do continue to operate without a battery, the alternator could stop working if a very large electrical load is turned on which causes the system voltage to momentarily drop. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=457555#457555 ________________________________ Message 3 _____________________________________ Time: 07:56:14 AM PST US Subject: AeroElectric-List: Re: Bendix King KY97A Tuning Problem From: "racerjerry" I am sure you know this already BUT... Before you tear it apart, make sure the problem is not just a loose knob set screw -------- Jerry King Read this topic online here: http://forums.matronics.com/viewtopic.php?p=457561#457561 ________________________________ Message 4 _____________________________________ Time: 08:50:19 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Hypothetical Battery Contactor Failure At 08:13 AM 6/30/2016, you wrote: > >Once an engine is running above idle, the battery no longer supplies >electrical power to the aircraft. The alternator does. Many >alternators will continue to operate if the battery is then >disconnected. The electrical current needed to power the alternator >field comes from the alternator output, whether the battery is >connected or not. There may be some alternators that will not >continue to run without a battery connected. Even for alternators >that do continue to operate without a battery, the alternator could >stop working if a very large electrical load is turned on which >causes the system voltage to momentarily drop. WWWaaaayyyy back when, it was generally assumed that running the aircraft sans battery was not a good thing to do. Before alternators, generator and battery switches were separate and generators would self-excite. Given that batteries are NOT good filters of power generation noise, it didn't matter if the battery was on-line or not. The earliest alternators on Cessnas (and indeed all other S.E. TC aircraft) were automotive derivatives. I was not privy to any investigative tests at Cessna but the corporate policy was that their airplanes should not be operated sans battery. Hence, the split rocker switch was birthed. Apparently, Beech experience was different. While many if not most of the smaller S.E. aircraft did the same battery-first-then-alternator switching protocol. Re: B-23 Sundowner panel excerpt below . . . Emacs! The Bonanza and Barons were different. The first regulator design I qualified for Beech was about 1978 and their procurement specification stated that no feature of the regulator's circuitry 'shall prevent the alternator from coming up self-excited above xxxx rpm". This was the first time I'd encountered an alternator EXPECTED to come up all by itself. The Bonanza and Barons had totally independent battery and alternator switches. Operation sans battery was not prohibited and in fact the system was designed to allow it. I've got a new electro-mechanical test bench under fabrication and will be doing some work on PM Dynamo rectifier/regulators. The same facility will allow me to explore and quantify the present state of the art in production alternators. In the mean time, as long as you don't hit the alternator with a really BIG load (which few system are capable of doing anyhow), the modern alternator runs self-excited and benefits immeasurably from battery presence with respect to noise. More details to follow. So the answer to the opening question on this thread is: "Loss of the battery contactor in flight will not produce a behavior likely to be noticed in the air." Bob . . . ________________________________ Message 5 _____________________________________ Time: 03:20:30 PM PST US Subject: AeroElectric-List: Re: Hypothetical Battery Contactor Failure From: "user9253" Thanks for the knowledgeable answer. Once your new test bench is up and running, it would be interesting to verify or disprove this statement quoted from the Rotax 912 Installation Manual, > Never sever connection between terminal C and B of regulator (e.g. by removal of a fuse) while the engine is running. Overvoltage and regulator damage can occur. I find that statement hard to believe. When voltage is removed from Rotax regulator terminal C, its DC output should shut off, not increase. Of course the AC voltage would increase due to lack of load, but not anymore than if all electrical loads were shut off. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=457567#457567 ________________________________ Message 6 _____________________________________ Time: 05:32:19 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Hypothetical Battery Contactor Failure At 04:20 PM 6/30/2016, you wrote: > >Thanks for the knowledgeable answer. Once your new test bench is up >and running, it would be interesting to verify or disprove this >statement quoted from the Rotax 912 Installation Manual, > > > Never sever connection between terminal C and B of regulator > (e.g. by removal of a fuse) while the engine is running. > Overvoltage and regulator damage can occur. If we had a VERIFIED copy of the schematic for the Ducatti R/R, the validity of that statement could be confirmed or debunked. I have seen THIS schematic offered from various sources over the years http://tinyurl.com/zfkte7c A simply analysis of this drawing demonstrates that "C" is both the voltage regulation sense lead -AND- power source for the low-level regulating circuity. Simple analysis of this schematic shows that disconnection of the C terminal causes the R/R to shut down . . . which is consistent with a legacy design philosophy for voltage regulators of all stripe. >I find that statement hard to believe. When voltage is removed from >Rotax regulator terminal C, its DC output should shut off, not >increase. Of course the AC voltage would increase due to lack of >load, but not anymore than if all electrical loads were shut off. This is an enduring problem with anecdotal data gleaned from the catacombs of hangar-lore. Open circuit voltage from the PM dynamo windings may indeed be the voltage referred to by the original assertions. Further, THAT voltage generated by the engine running cruise rpm just might be hazardous to the R/R . . . but without the benefit of original designers documentation, we might as well be discussing Slobovian politics over a pitcher of beer. In the TC world, we write specs, do test plans, carry out experiments in the lab and airplanes on the ground and airborne. Then we write test reports which form the foundation for design decisions or remedial actions to correct a deficiency. Without that report (assuming one was ever produced) the real meaning of the ideas floating around on forums and hangars are at risk for (1) being mis- interpreted and (2) being morphed with the telling and re-telling into an entirely new significance. If the FAA ever extends it's grip deeper into OBAM aviation, a very strong excused is bound to include our poor utilization of computing and communications tools to keep (1) and (2) in check. So I'm with you my friend. I think the assertion about the Rotax R/R is at best an idea that suffered too many re-tellings by individuals with little or no understanding. Bob . . . ________________________________ Message 7 _____________________________________ Time: 05:35:17 PM PST US From: "William Hunter" Subject: AeroElectric-List: Composite Aircraft and Lightning Strikes Hi All, There is a discussion brewing on the Velocity Owners Builders Association about composite aircraft and lightning strikes. What sparked (sorry) this discussion was a question about static wicks and if they could be useful on composite aircraft and now there is some good bantering going on about lightning strikes and composite aircraft...so...naturally I thought since there is some really sharp electrical folks on this forum I would ask you all for your feedback on the subject and I will certainly give you credit for your feedback and suggestions (of course I could not try to pass this knowledge off as being my own because that cat is already out of the bag and they would never believe it came from me). Anyhoo...here are some questions (if you think up others please feel free to add): -Would static wicks be beneficial to add to a composite aircraft? -If adding static wicks to a composite airplane, where should they be added? -Should control surfaces be bonded to the aircraft structure if static wicks are used (and even if static wicks are not used)? -Should all of the metal components of the aircraft be bonded together and if so what technique should be employed to do so? -Does anyone know of any lightning strike incidents to composite aircraft and if so what damage to the aircraft structure/components have occurred? -What causes lightning to be attracted to airplanes and/or why does lightning hit airplanes (yes, I can understand why lightning hits trees/buildings/other items that are connected to earth but an airplane is not connected to earth...if it had just taken off I could see the static in the wake leading to ground however an airplane in cruise flight is another story)? -Are composite aircraft more or less likely to be hit by lightning than metal airplanes? -Are there any techniques or design considerations that would mitigate the chance of lightning strikes on the composite aircraft and/or the damage being done should the aircraft be hit? -On production composite aircraft, what if any equipment/design considerations have been required by the FAA to be employed in reducing the chances of and/or in mitigating the effect of a lightning strike? -Some guys are discussing using Carbon Fiber or mesh being installed under the surfaces of the airplane to transfer the energy of a lightning strike so if a mesh of some sort is indeed used, will it help or hurt in reducing the chances of and/or in mitigating the effect of a lightning strike (if the mesh is not robust enough to conduct the extreme electrical current by a lightning strike could it make the problem worse (as a lightning rod on a house has a too small conductor then the lightning rod attracts the lightning and then once the lightning does actually hit the rod the conductor to ground melts and now the house structure becomes the conduit to ground)? Please dream up other thoughts in the area of lightning strikes and I will certainly forward them on. We appreciate your help in making the design of the Velocity aircraft more safe during this time of year!!! .. Cheers!!! Bill Hunter ________________________________ Message 8 _____________________________________ Time: 06:26:51 PM PST US Subject: Re: AeroElectric-List: Re: Hypothetical Battery Contactor Failure From: Charlie England On 6/30/2016 4:20 PM, user9253 wrote: > > Thanks for the knowledgeable answer. Once your new test bench is up and running, it would be interesting to verify or disprove this statement quoted from the Rotax 912 Installation Manual, > >> Never sever connection between terminal C and B of regulator (e.g. by removal of a fuse) while the engine is running. Overvoltage and regulator damage can occur. > I find that statement hard to believe. When voltage is removed from Rotax regulator terminal C, its DC output should shut off, not increase. Of course the AC voltage would increase due to lack of load, but not anymore than if all electrical loads were shut off. > > -------- > Joe Gores > I don't know squat about Rotax stuff or their manual, but... If it's a PM style alternator, and the regulator is a shunt style regulator, and breaking that C-B connection removes the shunt load, then I can see how the regulator might be damaged. If the regulator sensing/control semiconductors are still connected to the alternator output but the shunt *isn't*, then the alternator could well be able to create a high enough voltage to exceed the max voltage ratings of the devices. Having the shunt *in* the circuit would ensure that the voltage never got that high. Charlie ________________________________ Message 9 _____________________________________ Time: 08:44:55 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Composite Aircraft and Lightning Strikes > >Anyhoo...here are some questions (if you think up others please feel free to >add): > >-Would static wicks be beneficial to add to a composite aircraft? Depends. A 'static wick' is intended to REDUCE coronal resistance between CONDUCTIVE parts of the airframe and the surrounding atmosphere. Without static wicks, electro static potentials in the millions of volts can build up in various places on the airframe. The existance of high levels of static build up can manifest in (1) visible light (St. Elmo's Fire on prop tips, around window frames, sharp trailing edges), (2) radio noise that can totally cripple some systems and sometimes (3) excessive erosion. The purpose of a static wick is to ENCOURAGE dissipation of electro-static energies at LOW levels . . . levels too low to produce the deleterious effects cited. -If adding static wicks to a composite airplane, where should they be added? EXCELLENT question. Figuring out were to put them nn a metal airplane is not a simple task . . . an insulated airplne is whole different ball game. I've seen airplanes perched on insulating jacks and excited with bunches of volts while a technician walks around the outside probing potential leak-off points on the airframe with a very long test probe. This is a good start on figuring out where potentially >-Should control surfaces be bonded to the aircraft structure if static wicks >are used (and even if static wicks are not used)? > >-Should all of the metal components of the aircraft be bonded together and >if so what technique should be employed to do so? Can't think of a single reason to do such things. I think Burt Rutan may have uttered such an opinion WAaaayyyy back when about control surfaces on the Ez series aircraft . . . But I'm at a lost to imagine, much less demonstrate how the action would benefit anything. >-Does anyone know of any lightning strike incidents to composite aircraft >and if so what damage to the aircraft structure/components have occurred? One of our very own suffered just such an event http://tinyurl.com/hre2hkz >-What causes lightning to be attracted to airplanes and/or why does >lightning hit airplanes (yes, I can understand why lightning hits >trees/buildings/other items that are connected to earth but an airplane is >not connected to earth...if it had just taken off I could see the static in >the wake leading to ground however an airplane in cruise flight is another >story)? > >-Are composite aircraft more or less likely to be hit by lightning than >metal airplanes? Intuitively one might think so . . . but the airplane is only a triggering influence in what was going to be a strike whether the airplane was there or not. All images of airplanes being struck show the airplane in the middle of a strike that extends from one area of the storm (usually cloud) to another area or the ground. >-Are there any techniques or design considerations that would mitigate the >chance of lightning strikes on the composite aircraft and/or the damage >being done should the aircraft be hit? Yeah, it's called staying the @#$@ away from areas for which no practical invincability can be demonstrated. This included lightning, ice, high winds, hail, etc. >-On production composite aircraft, what if any equipment/design >considerations have been required by the FAA to be employed in reducing the >chances of and/or in mitigating the effect of a lightning strike? It's exaclty the OPPOSITE. We cannot nor do we attempt to avoid being struck. We must ASSUME we WILL be struck and design for measured and predicted stresses. >-Some guys are discussing using Carbon Fiber or mesh being installed under >the surfaces of the airplane to transfer the energy of a lightning strike so >if a mesh of some sort is indeed used, will it help or hurt in reducing the >chances of and/or in mitigating the effect of a lightning strike (if the >mesh is not robust enough to conduct the extreme electrical current by a >lightning strike could it make the problem worse (as a lightning rod on a >house has a too small conductor then the lightning rod attracts the >lightning and then once the lightning does actually hit the rod the >conductor to ground melts and now the house structure becomes the conduit to >ground)? Check with the Lancair and Glasair forums. These folks would come a close as anyone to knowing what was tried and either succeeded or failed to produce the desired mitigation of effects. There is a wealth of discussion on . . . http://tinyurl.com/zeay3x5 . . . this is NOT a trivial task. >Please dream up other thoughts in the area of lightning strikes and I will >certainly forward them on. > >We appreciate your help in making the design of the Velocity aircraft more >safe during this time of year!!! History is rife with examples of work done to make aircraft resistant to the effects of lightning strike. Lancair, Glassair and contemporaries wrestled with it. At Beech, we stayed with metal wings but the fuselage structures have large, flat conductive straps that run longitudinaly7 in the fuselage. These 'fixes' are tested in direct effects of lightning laboratories to show that people, structure and systems within the airplane remain intact after events that are ASSUMED WILL HAPPEN. The simple answer to the question is: "Yes, you CAN do things to airplanes of any stripe to reduce risk due to lightning strike . . . but it's not a simple task. A task deeply intertwined with issues of structural integrity, weight, aerodynamics . . . and cost. In flight school, we were well advised to stay away from ice and convective activity. Risks to body and airframe go up exponentially . . . while costs for mitigation of those risks are breathtaking. Adding any feature intended to mitigate environmental risk brings some human factor's issues with it. More that one pilot with boots, prop-deice and a windshield heater patch was willing to 'press on just a little further' . . . with more than simply disappointing outcome. The same effect could beset a pilot flying an airplane with lightning mitigation enhancements . . . enhancements that did not benefit from a through checkout in the lightning lab by folks who have been there, done that. Bob . . . ________________________________ Message 10 ____________________________________ Time: 08:52:04 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Hypothetical Battery Contactor Failure >If it's a PM style alternator, and the regulator is a shunt style >regulator, and breaking that C-B connection removes the shunt load, >then I can see how the regulator might be damaged. If the regulator >sensing/control semiconductors are still connected to the alternator >output but the shunt *isn't*, then the alternator could well be able >to create a high enough voltage to exceed the max voltage ratings of >the devices. Nobody has built a shunt style regulator in a very long time. A few small systems on motor bikes and snowmobiles popularized the simple design but the B&C regulators have never been shunt . . . the alleged schematic of the Ducatti R/R is also a series regulator. They are manufactured as a spares item but better regulators are so easy to design, there's no reason to stay with shunt style. >Having the shunt *in* the circuit would ensure that the voltage >never got that high. but it WOULD drive internal energy dissipation to the max and, give the demonstrably poor thermal management of many designs, could toast the device. But I'm pretty sure nobody builds/offers that control philosophy to on the product we're using. Bob . . . ________________________________ Message 11 ____________________________________ Time: 09:36:03 PM PST US Subject: AeroElectric-List: Re: Hypothetical Battery Contactor Failure From: "user9253" The Rotax (Ducati) rectifier/regulator is a switching-power-supply type of regulator that turns on for part of the dynamo AC cycle. There is no shunt. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=457572#457572 ________________________________ Message 12 ____________________________________ Time: 10:20:00 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Hypothetical Battery Contactor Failure >If it's a PM style alternator, and the regulator is a shunt style >regulator, and breaking that C-B connection removes the shunt load, >then I can see how the regulator might be damaged. If the regulator >sensing/control semiconductors are still connected to the alternator >output but the shunt *isn't*, then the alternator could well be able >to create a high enough voltage to exceed the max voltage ratings of >the devices. Nobody has built a shunt style regulator in a very long time. A few small systems on motor bikes and snowmobiles popularized the simple design but the B&C regulators have never been shunt . . . the alleged schematic of the Ducatti R/R is also a series regulator. They are manufactured as a spares item but better regulators are so easy to design, there's no reason to stay with shunt style. >Having the shunt *in* the circuit would ensure that the voltage >never got that high. but it WOULD drive internal energy dissipation to the max and, give the demonstrably poor thermal management of many designs, could toast the device. But I'm pretty sure nobody builds/offers that control philosophy to on the product we're using. Bob . . . ________________________________ Message 13 ____________________________________ Time: 11:43:00 PM PST US Subject: Re: AeroElectric-List: Composite Aircraft and Lightning Strikes From: Peter Pengilly Before getting really wound up about lightning protection first understand the risk and then figure the mitigation. Look at the accident statistics- how many light aircraft have been struck by lightning and not survived? The answer is very, very few - in the US and in Europe. For whatever reason. Thunderstorms kill many people but lightning does not. My conclusion is that airframe lightning protection is not worthwhile. Thunderstorm protection is difficult so I avoid them. Peter On 1 Jul 2016 04:50, "William Hunter" wrote: > billhuntersemail@gmail.com> > > Hi All, > > There is a discussion brewing on the Velocity Owners Builders Association > about composite aircraft and lightning strikes. > > What sparked (sorry) this discussion was a question about static wicks and > if they could be useful on composite aircraft and now there is some good > bantering going on about lightning strikes and composite > aircraft...so...naturally I thought since there is some really sharp > electrical folks on this forum I would ask you all for your feedback on the > subject and I will certainly give you credit for your feedback and > suggestions (of course I could not try to pass this knowledge off as being > my own because that cat is already out of the bag and they would never > believe it came from me). > > Anyhoo...here are some questions (if you think up others please feel free > to > add): > > -Would static wicks be beneficial to add to a composite aircraft? > > -If adding static wicks to a composite airplane, where should they be > added? > > -Should control surfaces be bonded to the aircraft structure if static > wicks > are used (and even if static wicks are not used)? > > -Should all of the metal components of the aircraft be bonded together and > if so what technique should be employed to do so? > > -Does anyone know of any lightning strike incidents to composite aircraft > and if so what damage to the aircraft structure/components have occurred? > > -What causes lightning to be attracted to airplanes and/or why does > lightning hit airplanes (yes, I can understand why lightning hits > trees/buildings/other items that are connected to earth but an airplane is > not connected to earth...if it had just taken off I could see the static in > the wake leading to ground however an airplane in cruise flight is another > story)? > > -Are composite aircraft more or less likely to be hit by lightning than > metal airplanes? > > -Are there any techniques or design considerations that would mitigate the > chance of lightning strikes on the composite aircraft and/or the damage > being done should the aircraft be hit? > > -On production composite aircraft, what if any equipment/design > considerations have been required by the FAA to be employed in reducing the > chances of and/or in mitigating the effect of a lightning strike? > > -Some guys are discussing using Carbon Fiber or mesh being installed under > the surfaces of the airplane to transfer the energy of a lightning strike > so > if a mesh of some sort is indeed used, will it help or hurt in reducing the > chances of and/or in mitigating the effect of a lightning strike (if the > mesh is not robust enough to conduct the extreme electrical current by a > lightning strike could it make the problem worse (as a lightning rod on a > house has a too small conductor then the lightning rod attracts the > lightning and then once the lightning does actually hit the rod the > conductor to ground melts and now the house structure becomes the conduit > to > ground)? > > Please dream up other thoughts in the area of lightning strikes and I will > certainly forward them on. > > We appreciate your help in making the design of the Velocity aircraft more > safe during this time of year!!! > > .. > > Cheers!!! > > Bill Hunter > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-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/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-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.