---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 01/19/15: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:55 AM - Re: Insulated ground cables? (Robert L. Nuckolls, III) 2. 01:36 PM - Alternator/regulator (Gary Burdett) 3. 02:51 PM - Power Generation without Battery? (Chris Mullins) 4. 03:20 PM - Re: Power Generation without Battery? (Ben) 5. 03:42 PM - Re: Power Generation without Battery? (Peter Pengilly) 6. 05:58 PM - Re: Insulated ground cables? (David Saylor) 7. 06:35 PM - Re: Power Generation without Battery? (Jeff Luckey) ________________________________ Message 1 _____________________________________ Time: 05:55:49 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Insulated ground cables? >Hi Bob et al. > >The fuel line is conductive aluminium - why would there be a static >build up, unless it were isolated completely from the rest of the >airframe by rubber fittings at every support as well as rubber hoses >connecting it to the rest of the fuel system? Surely no matter where >the pipe is grounded (by connecting it to the fuel tank, gascolator, >fuel selector switch or similar), that would dissipate any static >build up along the entire length of aluminium piping and anything >else connected to it by the AN fittings? I am particularly intrigued >by this having _just_ ordered 50' of aluminium fuel piping to refit >my Citabria's continuously perishing rubber fuel hoses. Not a static built up WITHIN the tube, but static currents circulating WITHOUT wherein two conductive entities are not electrically bonded to each others and some 'discharge' occurs between them. This is not a fire safety kind of issue but purely one of potential noise. Admittedly, this is an stretch in the extreme to apply this kind of reasoning to 99 percent of little airplanes . . . but there are folks who have listened well to their teachers with experience in high performance, high altitude and perhaps weapons-grade machines wherein the slightest risk for mission failure was treated as a national security issue. The question that Dave was pondering is probably not germane to any airplanes that we're interested in . . . and the narrative supporting the practice for what he is observing is not readily available to us. It's interesting to ponder the value of many of the process specifications I've encountered over the years. Beech and Cessna had libraries of them. If there's a failing of requirements laid out in hard document (or cultural rules-of-thumb), it's the dearth of background for why some things are a good idea and under what conditions they should . . . or need not be applied. The authors were long gone and could not be queried as to the foundation for the practice. Hence, things that may have been done in good faith and sound physics on some project years ago have been filtered down as part of the cultural boiler-plate; dutifully honored to this day . . . sometimes as more of a religion than a science. Sorta like the cultural obsession with oil pressure during the first seconds of an engine start. Charles Lindbergh may have personally experience broken oil circulation systems or perhaps his associates had personal experiences . . . but what is the likelihood of such an event today? Most automobiles are fitted with oil pressure switches that kill the fuel pump when no pressure is sensed. This prevents a tank mounted pump from driving a broken fuel line after the engine stops from fuel starvation. The engine is more likely the become 'inop' due to fuel plumbing problems (or shorted bus feeder or smoked electrical system) than for lack of lubrication. >Could it not be as a mechanical restraint in the event of an >accident to ensure that when the airframe crumples the pipe bends in >a particular fashion to reduce the risk of kinking and spraying fuel >all over a fire...? Without published background for a particular practice, we'll never know for sure. But I think it's more simplistic. AC43-13 focus is on robust mounting with allowances for necessary movement while maintaining clearances between antagonistic components and mitigating the effects of environment. The astute systems installer views power steering hoses, fuel lines, brake lines, control cables, wire bundles, and all manner of moving parts as potential antagonists against each other. The art of their craft includes a running narrative FMEA pondering all the ways these components may fail to function due to interference by another component combined perhaps with an environmental stress. I used to field worrisome questions about 'exposed' bus bars behind the panel with the following: "Okay, with your choice of hammers, saws, clippers or any other tool, crawl under the panel and do what ever it takes to bring some part of your airplane against that exposed bus bar. If you find some component at risk for such interference, what is the likelihood of that happening in flight? If there is strong likelihood, is it better to shield the bus . . . or improve on the mounting and robustness of the interfering part?" From narratives like this . . . and lessons learned . . . that process specs are crafted and become part of THE WORD . . . a word often adopted on faith after the supporting narrative is lost to history. But we can hone our own awareness of risks by constantly reviewing the capabilities, limits and vulnerabilities of components we bolt to our airplanes. When you bolt in a nice, new, feather light lithium battery, you ponder . . . "Gee, is this little feller going to be happy in my airplane?" When you bundle a bus feeder line together with come control cables . . . "Hmmmmm . . . can those guys get each other into trouble like squabbling two-year-olds?" The potential for problematic combinations is huge but they're all based on exceedingly simple ideas with risks for failure to sift through the beans for pebbles . . . before the pot goes on the stove. Bob . . . ________________________________ Message 2 _____________________________________ Time: 01:36:28 PM PST US Subject: AeroElectric-List: Alternator/regulator From: Gary Burdett I have a JD/yanmar PM alternator and regulator with crowbar circuit. Voltage was starting to run over 15 volts at cruise rpms. Replaced battery and regulator, now hits 15.5 volts at anything over 2400 rpms on first test with a fully charged battery..???? Sent from my iPad ________________________________ Message 3 _____________________________________ Time: 02:51:31 PM PST US Subject: AeroElectric-List: Power Generation without Battery? From: Chris Mullins Bob, I am building a Carbon Cub - a lightweight experimental design for backcountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the engine with any 1 of those 3 failed. I want to use a lithium battery for starting purposes only. I am not worried about battery only endurance with 2 other power sources. Alternator technology is mature, but Li batteries seem to be still evolving. Some type of battery fault would seem be a likely failure mode in my planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery). I plan to use your Z12 or Z13 architecture. People I speak with advise me that alternators (even the SD8) are dependent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline. Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem to still be legitimate issues with the current Li crop. At the very least they remain relatively unproven. So I am concerned about the Li battery being a single point of failure capable of stopping the engine. How can I design around this problem? Chris M ________________________________ Message 4 _____________________________________ Time: 03:20:46 PM PST US From: "Ben" Subject: Re: AeroElectric-List: Power Generation without Battery? Pmag ????? Ben Haas N801BH www.haaspowerair.com ---------- Original Message ---------- From: Chris Mullins Subject: AeroElectric-List: Power Generation without Battery? Bob, I am building a Carbon Cub - a lightweight experimental design for backc ountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the en gine with any 1 of those 3 failed. I want to use a lithium battery for starting purposes only. I am not wor ried about battery only endurance with 2 other power sources. Alternator technology is mature, but Li batteries seem to be still evolv ing. Some type of battery fault would seem be a likely failure mode in m y planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or e ven physically remove the battery). I plan to use your Z12 or Z13 architecture. People I speak with advise me that alternators (even the SD8) are depend ent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline. Recent revelations regarding the Challenger/Aerovoltz scenario aside, th ere seem to still be legitimate issues with the current Li crop. At the very least they remain relatively unproven. So I am concerned about the Li battery being a single point of failure c apable of stopping the engine. How can I design around this problem? ======================== ======================== ======================== ======================== ======================== ========= ____________________________________________________________ The Next Big Thing 3 Companies Running Big Cable Out of Business http://thirdpartyoffers.netzero.net/TGL3241/54bd90f12addb10f06697st03duc ________________________________ Message 5 _____________________________________ Time: 03:42:58 PM PST US Subject: Re: AeroElectric-List: Power Generation without Battery? From: Peter Pengilly Use a lead acid battery? Something like a PC545 at 11.4 lb may be an acceptable weight penalty? Peter On 19 Jan 2015 23:03, "Chris Mullins" wrote: > Bob, > I am building a Carbon Cub - a lightweight experimental design for > backcountry use. It will use a fully electrically dependent Lycoming > engine. I plan on 1 battery/2 alternators, and I desire the system to run > the engine with any 1 of those 3 failed. > > I want to use a lithium battery for starting purposes only. I am not > worried about battery only endurance with 2 other power sources. > > Alternator technology is mature, but Li batteries seem to be still > evolving. Some type of battery fault would seem be a likely failure mode in > my planned system. (I'd like to monitor battery temp using a probe and my > on board electronics, and to have some way to electrically isolate or even > physically remove the battery). > > I plan to use your Z12 or Z13 architecture. > > People I speak with advise me that alternators (even the SD8) are > dependent on a functioning battery in the system, and that they will cease > to function if the battery fails or is taken offline. > > Recent revelations regarding the Challenger/Aerovoltz scenario aside, > there seem to still be legitimate issues with the current Li crop. At the > very least they remain relatively unproven. > > So I am concerned about the Li battery being a single point of failure > capable of stopping the engine. > > How can I design around this problem? > > Chris M > > * > > > * > > ________________________________ Message 6 _____________________________________ Time: 05:58:47 PM PST US From: David Saylor Subject: Re: AeroElectric-List: Insulated ground cables? Here's a picture of the clamp. It clearly has the contact patch that Roger described. The fit is not at all tight. It's cabled to the wing skin under a nacelle. The cable attaches to the skin about 1.5" from the bulkhead fitting supporting the tube... Thankfully, if the tube comes completely disconnected at each end from it's fittings, it still has a path to ground...(kidding). I still don't know the original intent, but the owner is satisfied that the fuel lines are grounded. Mission accomplished. Thanks for all the input, --Dave [image: Inline image 1] ________________________________ Message 7 _____________________________________ Time: 06:35:55 PM PST US From: Jeff Luckey Subject: Re: AeroElectric-List: Power Generation without Battery? Chris, If your mission profile could put you in the back country with ground support hundreds of miles away, you may want to consider a few ideas: 1. Consider changing architecture to 2 batteries & 1 alternator. If your only battery goes dead or has diminished capacity due to extreme cold, you done. Having an extra alternator won't get the engine started. 2. Maybe this is not the place for un-proven lithium battery technology. Again, if your survival depends on it, you may want to go w/ technology that has a proven track record. -Jeff On Monday, January 19, 2015 3:51 PM, Peter Pengilly wrote: Use a lead acid battery? Something like a PC545 at 11.4 lb may be an acceptable weight penalty? Peter On 19 Jan 2015 23:03, "Chris Mullins" wrote: Bob, >I am building a Carbon Cub - a lightweight experimental design for backcountry use. It will use a fully electrically dependent Lycoming engine. I plan on 1 battery/2 alternators, and I desire the system to run the engine with any 1 of those 3 failed. > >I want to use a lithium battery for starting purposes only. I am not worried about battery only endurance with 2 other power sources. > >Alternator technology is mature, but Li batteries seem to be still evolving. Some type of battery fault would seem be a likely failure mode in my planned system. (I'd like to monitor battery temp using a probe and my on board electronics, and to have some way to electrically isolate or even physically remove the battery). > >I plan to use your Z12 or Z13 architecture. > >People I speak with advise me that alternators (even the SD8) are dependent on a functioning battery in the system, and that they will cease to function if the battery fails or is taken offline. > > >Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem to still be legitimate issues with the current Li crop. At the very least they remain relatively unproven. > >So I am concerned about the Li battery being a single point of failure capable of stopping the engine. > >How can I design around this problem? > > >Chris M > >_blank">www.aeroelectric.com .com" target="_blank">www.buildersbooks.com ="_blank">www.homebuilthelp.com ="_blank">www.mypilotstore.com ank">www.mrrace.com _blank">http://www.matronics.com/contribution ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List tp://forums.matronics.com ------------------------------------------------------------------------------------- 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.