---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 07/27/18: 12 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:54 AM - Re: Re: Grounding architecture (Robert L. Nuckolls, III) 2. 07:59 AM - Re: Re: Grounding architecture (Bill Watson) 3. 08:02 AM - Re: Grounding architecture (Rocketman1988) 4. 08:02 AM - Re: Re: Grounding architecture (Robert L. Nuckolls, III) 5. 08:07 AM - Re: Re: Grounding architecture (FLYaDIVE) 6. 08:49 AM - Re: Re: Grounding architecture (Alec Myers) 7. 09:48 AM - Re: Re: Grounding architecture (Charlie England) 8. 10:16 AM - Re: Re: Grounding architecture (Alec Myers) 9. 01:57 PM - Re: Re: Grounding architecture (Robert L. Nuckolls, III) 10. 02:12 PM - Re: Re: Grounding architecture (Robert L. Nuckolls, III) 11. 06:20 PM - Re: Re: Grounding architecture (Kelly McMullen) 12. 07:49 PM - Re: Re: Grounding architecture (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 07:54:57 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Grounding architecture At 09:13 PM 7/26/2018, you wrote: >Nothing beats a copper wire ground on a plane. >There is no reason why you can not do >both...=C2 A wire from the battery to the >Firewall/Ground Buss and a short Ground wire to the airframe.=C2 =C2 Can you support your assertion with an analysis of the physics? Aluminum is not a poor conductor. In fact, overhead transmission lines for long distance power distribution are aluminum over steel cables. If the resistance between battery ground in the tail and a firewall ground block is already on the order of .001 ohms, how much of the airframe current is shunted off onto a paralleled wire? What benefit is realized by this 'sharing' of battery current? Except when cranking the engine, the total current flowing through the battery ground path will not exceed alternator capacity and then only for the minutes needed to top of the battery. Battery currents in normal operations are essentially zero . . . Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:59:54 AM PST US Subject: Re: AeroElectric-List: Re: Grounding architecture From: Bill Watson Bob's point is that it is completely unnecessary. I have a robust battery to ground connection at the battery and at my firewall grounding bar: Battery Mount and Ground (680s) Firewall ground You can see in the first link the 8AWG white wire going forward to the grounding bar. If it is unnecessary then I consider a bad plan. An error on my part that simply added weight. On 7/26/2018 3:15 PM, Rocketman1988 wrote: > > So is running a 2 AWG cable from the aft mounted batteries on an RV 10 to a firewall stud a bad plan? Would a basic airframe ground be the better option,i.e. ground the batteries at their aft mounted location? > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=481866#481866 > > --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 3 _____________________________________ Time: 08:02:23 AM PST US Subject: AeroElectric-List: Re: Grounding architecture From: "Rocketman1988" Bob, so is there anything wrong with a grounding plan similar to the Z-15 for the Rv-10? It is simple enough to run that 2awg wire now, not so much later. For reference, the main 2awg wire running from the battery to the starter contactor is about 12 feet long. The ground would obviously be about the same. Thanks in advance... Read this topic online here: http://forums.matronics.com/viewtopic.php?p=481880#481880 ________________________________ Message 4 _____________________________________ Time: 08:02:38 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Grounding architecture At 02:15 PM 7/26/2018, you wrote: > > >So is running a 2 AWG cable from the aft mounted batteries on an RV >10 to a firewall stud a bad plan? Would a basic airframe ground be >the better option,i.e. ground the batteries at their aft mounted location? It's not 'bad' . . . just unnecessary when a lighter alternative is available. Airplanes like Beechjets and Hawkers have all manner of airframe grounds that carry currents from amps to thousands of amps (starter inrush). There are NO wires installed to avoid running ground returns through airframes. Well, almost no wires . . . had a case on a T1 trainer (Beechjet) in Mississippi where four strands of 2awg were routed from tail to nose to carry power and ground to a nose mounted air conditioning compressor motor (3+ horsepower). This antagonist was so profound that running motor current over so much of the airframe was a noise disaster. But that's another story. Bob . . . ________________________________ Message 5 _____________________________________ Time: 08:07:34 AM PST US From: FLYaDIVE Subject: Re: AeroElectric-List: Re: Grounding architecture Charlie: How can an aluminum - Riveted skin be a lower resistance than a straight run of copper wire? It can't since aluminum has a higher resistance than copper. To that add the poor connection of riveted panels. Also remember aluminum sheeting is clear coat anodized. Barry On Thu, Jul 26, 2018 at 10:58 PM, Charlie England wrote: > ceengland7@gmail.com> > > On 7/26/2018 2:15 PM, Rocketman1988 wrote: > >> Rocketman@etczone.com> >> >> So is running a 2 AWG cable from the aft mounted batteries on an RV 10 to >> a firewall stud a bad plan? Would a basic airframe ground be the better >> option,i.e. ground the batteries at their aft mounted location? >> >> I think the idea is that running the extra ground wire forward is not a > *bad* idea; just an unnecessary one, in a metal a/c. The airframe will be > a lower resistance ground path than any practically size wire. > > Problems related to the ground loop issue are usually limited to audio > gear. I'm sure Bob can give you a better, more precise description of what > happens. But my layman's description is this: If a low level signal, like > audio, shares its ground return path with much stronger, 'noisy' electrical > signals, like a strobe, the strobe noise can effectively become part of the > audio signal, and you get the noise in the audio system. To prevent that, > you use the 'forest of tabs' located somewhere near the audio (and other > low signal level) gear, and run all low level signals to that spot instead > of through the airframe. That keeps the ground paths of the low level stuff > & the 'noisy' stuff separate. > > Charlie > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > ________________________________ Message 6 _____________________________________ Time: 08:49:48 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: Re: Grounding architecture Because the cross sectional area of the fuselage is many times greater than t he cross section of the putative wire, and rivets are great conductors? On Jul 27, 2018, at 16:07, FLYaDIVE wrote: Charlie: How can an aluminum - Riveted skin be a lower resistance than a straight run of copper wire? It can't since aluminum has a higher resistance than copper. To that add th e poor connection of riveted panels. Also remember aluminum sheeting is clear coat anodized. Barry > On Thu, Jul 26, 2018 at 10:58 PM, Charlie England w rote: .com> > >> On 7/26/2018 2:15 PM, Rocketman1988 wrote: ne.com> >> >> So is running a 2 AWG cable from the aft mounted batteries on an RV 10 to a firewall stud a bad plan? Would a basic airframe ground be the better op tion,i.e. ground the batteries at their aft mounted location? >> > I think the idea is that running the extra ground wire forward is not a *b ad* idea; just an unnecessary one, in a metal a/c. The airframe will be a l ower resistance ground path than any practically size wire. > > Problems related to the ground loop issue are usually limited to audio gea r. I'm sure Bob can give you a better, more precise description of what happ ens. But my layman's description is this: If a low level signal, like audio, shares its ground return path with much stronger, 'noisy' electrical signal s, like a strobe, the strobe noise can effectively become part of the audio s ignal, and you get the noise in the audio system. To prevent that, you use t he 'forest of tabs' located somewhere near the audio (and other low signal l evel) gear, and run all low level signals to that spot instead of through th e airframe. That keeps the ground paths of the low level stuff & the 'noisy' stuff separate. > > Charlie > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > > ========================= > - > Electric-List" rel="noreferrer" target="_blank">http://www.matronics.c om/Navigator?AeroElectric-List > ========================= > FORUMS - > eferrer" target="_blank">http://forums.matronics.com > ========================= > WIKI - > errer" target="_blank">http://wiki.matronics.com > ========================= > b Site - > -Matt Dralle, List Admin. > rel="noreferrer" target="_blank">http://www.matronics.com/contribution > ========================= > > > ________________________________ Message 7 _____________________________________ Time: 09:48:58 AM PST US Subject: Re: AeroElectric-List: Re: Grounding architecture From: Charlie England That, and the unrelated point that no aircraft grade aluminum sheet is anod ized, clear or otherwise=2E Barry, where are you getting your misinformati on? Charlie =81=A3Charlie=8B On Jul 27, 2018, 10:55 AM, at 10:5 5 AM, Alec Myers wrote: >Because the cross sectional area of the fuselage is many times greater >than the cross section of the putative wire, and rivets are great >conductors? > >On Jul 27, 2018, at 16: 07, FLYaDIVE wrote: > >Charlie: > >How can an alumin um - Riveted skin be a lower resistance than a >straight run of copper wire ? >It can't since aluminum has a higher resistance than copper=2E To that >add the poor connection of riveted panels=2E >Also remember aluminum sheet ing is clear coat anodized=2E > >Barry > >> On Thu, Jul 26, 2018 at 10:58 PM, Charlie England > wrote: >> --> AeroElectric-Li st message posted by: Charlie England > >> >>> On 7/26/2018 2:15 PM, Rocketman1988 wrote: >>> --> AeroElectric-List message p osted by: "Rocketman1988" > >>> >>> So is running a 2 AWG cable from the aft mounted batteries on an RV >10 to a firewall st ud a bad plan? Would a basic airframe ground be the >better option,i=2Ee =2E ground the batteries at their aft mounted location? >>> >> I think the idea is that running the extra ground wire forward is not >a *bad* idea; j ust an unnecessary one, in a metal a/c=2E The airframe >will be a lower re sistance ground path than any practically size wire=2E >> >> Problems rela ted to the ground loop issue are usually limited to >audio gear=2E I'm sure Bob can give you a better, more precise >description of what happens=2E Bu t my layman's description is this: If a >low level signal, like audio, shar es its ground return path with much >stronger, 'noisy' electrical signals, like a strobe, the strobe noise >can effectively become part of the audio s ignal, and you get the noise >in the audio system=2E To prevent that, you u se the 'forest of tabs' >located somewhere near the audio (and other low si gnal level) gear, and >run all low level signals to that spot instead of th rough the airframe=2E >That keeps the ground paths of the low level stuff & the 'noisy' stuff >separate=2E >> >> Charlie >> >> --- >> This email has been checked for viruses by Avast antivirus software=2E >> https://www=2Ea vast=2Ecom/antivirus >> >> >> ============== ===========> - >> Electric-List" rel="noreferrer" > target="_blank">http://www=2Ematronics=2Ecom/Navigator?AeroElectric-List >> ======================== => FORUMS - >> eferrer" target="_blank">http://forums=2Ematronics=2Ecom >> ======================= ==> WIKI - >> errer" target="_blank">http://wiki=2Ematronics=2Ecom >> ======================== => b Site - >> -Matt Dralle, List Admin=2E >> rel="noreferrer " >target="_blank">http://www=2Ematronics=2Ecom/contribution >> === ======================> >> >> ________________________________ Message 8 _____________________________________ Time: 10:16:53 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: Re: Grounding architecture right... it=99s a strong aluminium alloy clad in pure (soft, but corro sion resistant) aluminium. Hence =9CAlclad=9D. On Jul 27, 2018, at 17:48, Charlie England wrote: That, and the unrelated point that no aircraft grade aluminum sheet is anodi zed, clear or otherwise. Barry, where are you getting your misinformation? Charlie Charlie > On Jul 27, 2018, at 10:55 AM, Alec Myers wrote: > Because the cross sectional area of the fuselage is many times greater tha n the cross section of the putative wire, and rivets are great conductors? > > On Jul 27, 2018, at 16:07, FLYaDIVE wrote: > > Charlie: > > How can an aluminum - Riveted skin be a lower resistance than a straight r un of copper wire? > It can't since aluminum has a higher resistance than copper. To that add t he poor connection of riveted panels. > Also remember aluminum sheeting is clear coat anodized. > > Barry > >> On Thu, Jul 26, 2018 at 10:58 PM, Charlie England w rote: l.com> >> >>> On 7/26/2018 2:15 PM, Rocketman1988 wrote: one.com> >>> >>> So is running a 2 AWG cable from the aft mounted batteries on an RV 10 t o a firewall stud a bad plan? Would a basic airframe ground be the better o ption,i.e. ground the batteries at their aft mounted location? >>> >> I think the idea is that running the extra ground wire forward is not a * bad* idea; just an unnecessary one, in a metal a/c. The airframe will be a l ower resistance ground path than any practically size wire. >> >> Problems related to the ground loop issue are usually limited to audio ge ar. I'm sure Bob can give you a better, more precise description of what hap pens. But my layman's description is this: If a low level signal, like audio , shares its ground return path with much stronger, 'noisy' electrical signa ls, like a strobe, the strobe noise can effectively become part of the audio signal, and you get the noise in the audio system. To prevent that, you use the 'forest of tabs' located somewhere near the audio (and other low signal level) gear, and run all low level signals to that spot instead of through t he airframe. That keeps the ground paths of the low level stuff & the 'noisy ' stuff separate. >> >> Charlie >> >> --- >> This email has been checked for viruses by Avast antivirus software. >> https://www.avast.com/antivirus >> >> >> ========================= >> - >> Electric-List" rel="noreferrer" target="_blank">http://www.matronics. com/Navigator?AeroElectric-List >> ========== >> FORUMS - >> eferrer" target="_blank">http://forums.matronics.com >> ========================= >> WIKI - >> errer" target="_blank">http://wiki.matronics.com >> ========================= >> b Site - >> -Matt Dralle, List Admin. >> rel="noreferrer" target="_blank">http://www.matronics.com/contributio n >> ========== >> >> >> > ________________________________ Message 9 _____________________________________ Time: 01:57:24 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Grounding architecture At 10:07 AM 7/27/2018, you wrote: >Charlie: > >How can an aluminum - Riveted skin be a lower >resistance than a straight run of copper wire? It's a 'cross section' thing. The square inches of conductor cross-section from nose to tail of a metal airplane is a whole lot bigger than any practical chunk of wire you might choose to run. >It can't since aluminum has a higher resistance than copper. Depending on the alloy, aluminum will present a volume resistivity on the order of 2.82x10^-8 while copper will be about 1.68x10^-8 or 67% higher. Given that the cross section of wire goes up with the square of diameter, an aluminum wire only needs to be about 30% larger. This speaks to the success of Eric's offer for copper- clad, fine-strand FAT wires. https://goo.gl/8HTqEV In spite of being larger wires, they are lighter for the same electrical performance. This also speaks to the preference for using aluminum in long distance transmission lines . . . the lighter wire makes for a smaller steel core in the makeup of the strands. >=C2 To that add the poor connection of riveted panels. A properly sized rivet SWELLS up in the hole with such force that a gas-tight connection is achieved even when the sheet is coated with corrosion preventatives. >Also remember aluminum sheeting is clear coat anodized. Yes, there are come chemical passivation processes offered for aluminum sheet . . . which has zero influence on the electrical integrity of riveted joints. Bob . . . ________________________________ Message 10 ____________________________________ Time: 02:12:32 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Grounding architecture At 10:01 AM 7/27/2018, you wrote: > > >Bob, so is there anything wrong with a grounding plan similar to the >Z-15 for the Rv-10? It is simple enough to run that 2awg wire now, >not so much later. For reference, the main 2awg wire running from >the battery to the starter contactor is about 12 feet long. The >ground would obviously be about the same. If you don't mind the weight penalty and cost of installation, no . . . it will perform as advertised. I've updated View -A- to Z-15 to add a note on the battery(-) connection to (1) suggest it be used as shown on forward/rear mounted batteries in plastic and forward mounted batteries in metal airplanes. It can be replaced with local grounding of the battery on a metal airplane. https://goo.gl/NtQT1P We've discussed this on several occasions over the years but the conclusions didn't get carried over to Z-15. Bob . . . ________________________________ Message 11 ____________________________________ Time: 06:20:33 PM PST US Subject: Re: AeroElectric-List: Re: Grounding architecture From: Kelly McMullen You are comparing 2AWG copper or lesser, to almost infinite size aluminum, which is NOT clear coat anodized, never has been, as far as the common varieties such as 2024T3 or 5056. The 2024 in fact has a thin layer of pure aluminum at the surface, known as alclad. Rivets are in fact gas tight metal to metal connections. Have you any data to assert that the copper has less resistance? Kelly On 7/27/2018 10:07 AM, FLYaDIVE wrote: > Charlie: > > How can an aluminum - Riveted skin be a lower resistance than a straight > run of copper wire? > It can't since aluminum has a higher resistance than copper. To that > add the poor connection of riveted panels. > Also remember aluminum sheeting is clear coat anodized. > > Barry > > On Thu, Jul 26, 2018 at 10:58 PM, Charlie England > wrote: > > > > > On 7/26/2018 2:15 PM, Rocketman1988 wrote: > > > > > So is running a 2 AWG cable from the aft mounted batteries on an > RV 10 to a firewall stud a bad plan? Would a basic airframe > ground be the better option,i.e. ground the batteries at their > aft mounted location? > > I think the idea is that running the extra ground wire forward is > not a *bad* idea; just an unnecessary one, in a metal a/c. The > airframe will be a lower resistance ground path than any practically > size wire. > > Problems related to the ground loop issue are usually limited to > audio gear. I'm sure Bob can give you a better, more precise > description of what happens. But my layman's description is this: If > a low level signal, like audio, shares its ground return path with > much stronger, 'noisy' electrical signals, like a strobe, the strobe > noise can effectively become part of the audio signal, and you get > the noise in the audio system. To prevent that, you use the 'forest > of tabs' located somewhere near the audio (and other low signal > level) gear, and run all low level signals to that spot instead of > through the airframe. That keeps the ground paths of the low level > stuff & the 'noisy' stuff separate. > > Charlie > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > > =================================== > - > Electric-List" rel="noreferrer" > target="_blank">http://www.matronics.com/Navigator?AeroElectric-List > =================================== > FORUMS - > eferrer" target="_blank">http://forums.matronics.com > =================================== > WIKI - > errer" target="_blank">http://wiki.matronics.com > =================================== > b Site - > -Matt Dralle, List Admin. > rel="noreferrer" target="_blank">http://www.matronics.com/contribution > =================================== > > > > ________________________________ Message 12 ____________________________________ Time: 07:49:34 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Grounding architecture At 08:19 PM 7/27/2018, you wrote: > >You are comparing 2AWG copper or lesser, to almost infinite size >aluminum, which is NOT clear coat anodized, never has been, as far >as the common varieties such as 2024T3 or 5056. The 2024 in fact has >a thin layer of pure aluminum at the surface, known as alclad. >Rivets are in fact gas tight metal to metal connections. >Have you any data to assert that the copper has less resistance? It's a fact of physics that copper is a better conductor than aluminum in the same cross section. The harder thing to wrap your arms around is to consider the effective cross section of a fuselage structure covered in a relatively thin layer of aluminum. The path traveled by current flows through the airframe do not move is straight lines but will concentrate over the areas of least resistance. There have been studies and experiments run for effects of direct lightning strikes. Intuitively we can assert that small aircraft will have higher resistance between similar locations on the airframe . . . but for this thread, it's sufficient to assert that adding an extra wire between battery(-) in the tail and firewall ground stud will produce no demonstrable benefit. A 12' run of 22759 2AWG at ~0.28 pounds/ft adds about 3.4 pounds to the aircraft's empty weight. 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