AeroElectric-List Digest Archive

Thu 07/12/12


Total Messages Posted: 18



Today's Message Index:
----------------------
 
     1. 02:45 AM - Re: grounding procedures (toddheffley)
     2. 08:23 AM - Re: Z12 Alternator Amps (RV7ASask)
     3. 08:37 AM - General Aviation Savior?? (jonlaury)
     4. 08:48 AM - Battery question not aeroplan related (Werner Schneider)
     5. 08:52 AM - Re: grounding procedures (Robert L. Nuckolls, III)
     6. 09:06 AM - Re: Re: grounding procedures (Robert L. Nuckolls, III)
     7. 09:26 AM - Re: grounding procedures (Ed Anderson)
     8. 10:30 AM - Re: Re: Z12 Alternator Amps (Robert L. Nuckolls, III)
     9. 10:39 AM - Re: General Aviation Savior?? (Robert L. Nuckolls, III)
    10. 10:46 AM - Re: Battery question not aeroplan related (Robert L. Nuckolls, III)
    11. 10:53 AM - Re: grounding procedures (Robert L. Nuckolls, III)
    12. 11:10 AM - Re: Re: Z12 Alternator Amps (Bill Bradburry)
    13. 12:43 PM - Re: Re: Z12 Alternator Amps (Bob McCallum)
    14. 12:51 PM - Re: Re: grounding procedures (Richard Girard)
    15. 01:48 PM - Re: Battery question not aeroplan related (Werner Schneider)
    16. 02:42 PM - Re: Over-voltage Circuit Trips (Robert L. Nuckolls, III)
    17. 03:36 PM - Re: grounding procedures (Jeff Luckey)
    18. 03:56 PM - Re: grounding procedures (Ed Anderson)
 
 
 


Message 1


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    Time: 02:45:53 AM PST US
    Subject: Re: grounding procedures
    From: "toddheffley" <public@toddheffley.com>
    I was always doubted the importance of using a metal funnel until I fueled our champ on a dry day with a large plastic funnel. I was standing in the tire so I was also insulated. A charge built up strong enough to attract the hair on my arm to stand up toward the cowl. No Harm, No Foul. It was a warning to alter my behaviour before a really bad indecent occurred. todd -------- WWW.toddheffley.com www.theinterconnectco.com for lighting products AV-TS.com for Jet Aircraft Test Equipment Read this topic online here: http://forums.matronics.com/viewtopic.php?p=378072#378072


    Message 2


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    Time: 08:23:37 AM PST US
    Subject: Re: Z12 Alternator Amps
    From: "RV7ASask" <rv7alamb@sasktel.net>
    Early this morning I was in the hanger and did some major testing. I disconnected the 20 Amp Shunt I received originally from B&C when I got the 20 Amp Aux Alternator. I then temporarily installed a 40 Amp Shunt I had received from Dynon but had not used. A ground run gave all the correct and expected indications. The Aux Alternator is now showing the same Amps as the Main. Thanks to everyone who weighed in on this issue. It looks like I have a solution. Regards David Lamb Read this topic online here: http://forums.matronics.com/viewtopic.php?p=378099#378099


    Message 3


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    Time: 08:37:01 AM PST US
    Subject: General Aviation Savior??
    From: "jonlaury" <jonlaury@impulse.net>
    The following arrived in my Inbox today. I subscribe to a fascinating tech newsletter (www.yet2.com,click yet2.com Marketplace, for free sign-up) and I know this list is for electrical stuff, but we all share the same interest in technology and I thought many of you would be inspired by the stuff that turns up here. I hope you enjoy the article. This technology could be a turning point in decreasing the cost of building airplanes. Cheers, John Uni-body composite plastic chassis Developed at a Fortune 500 company, this innovation is a patented one-piece fiber-reinforced plastic composite chassis produced by the sheet molding compression (SMC) production method of manufacturing. The composite structural material used is high-glass-content vinyl ester, toughened with urethane for good fatigue and damage tolerance. The clamp-to-clamp molding cycle time for this complete one-piece composite chassis is four (4) minutes. Composite structural golf cart chassis molded by the SMC method have been built and tested, and proved to be fully operational and functional. The major advantage of this solution is to reduce the part count from 150-200 to one molded piece with intrinsic corrosion resistance. Moreover, the flexibility in composite design allows the molding of different features to allow customization of the vehicle for different uses and different power trains. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=378102#378102


    Message 4


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    Time: 08:48:54 AM PST US
    From: Werner Schneider <glastar@gmx.net>
    Subject: Battery question not aeroplan related
    Hello Bob and all, as it is not directly aeroplane related I apologize and hope it is still acceptable to post in that area, at the end it's about batteries an their differences I have an UPS which I neglected a bit and it failed recently; the batteries in there had an ugly shape but no spill, voltage was below 2V for each (12v 7.2A nominal) I looked now for replacement from Panasonic (using a 17A and now 20A since years in my plane). Interestingly enough they have two types of this: LC-R127R2PG1 UP-VW1245P1 price difference (in Switzerland) is 28CHF for the 1st and 49.80CHF for the 2nd, that is quite a bit as I need a set of 4 . We have a bit an unstable (overloaded) power net so the UPS does get in action at least once a month. I had a hard time to identify any facts why I should go the more expensive way (a general statement, that UP-VW has double the life of a LC-R was all I found). Any recommendation you could give in that case? Many thanks for the great support of this list! Werner do not archive


    Message 5


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    Time: 08:52:54 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: grounding procedures
    At 08:46 PM 7/11/2012, you wrote: >soooooooooooo my tanks are grounded to my engine. am i safe to >attach a wire from my fuel nozzle to my exhaust pipe or does the >wire need to go to the tank filler neck? [that doesn't make sense to me] > bob noffs The word "grounded" is poorly understood and in this discussion poorly used. As we've studied in other conversations, having "lots of grounds" can be deleterious to system performance in terms of noised conducted from one system to another. This static charge thing, like most studies of physics is an energy management issue. We have an energy source (motion between dissimilar materials in close proximity), energy storage (capacitance - proportional to surface area of mass carrying a charge), potential pathways for the two masses to exchange levels of charge, series resistance of those pathways, and finally open air gaps in the discharge path were a spark might form that is surrounded by a flammable mixture. The legacy hazard from which all these discussions arise are grounded in the management of charges stored on LARGE surface areas (air transport/military aircraft and fuel trucks or underground fueling systems. BIG numbers in terms of potential energy to be released in that worrisome air-gap. I'll refer readers to a couple of documents I've posted to Aeroelectric.com at http://tinyurl.com/7et4jj5 These two documents speak to 'modeling' the human body for the purposes of carrying out standardized tests for ESD vulnerability. Given the surface area of adult humans to be on the order of 1.5 to 2 square meters, they are 'modeled' as 100 picofarad capacitors. Further the ability to conduct a charge off that 'capacitor' is limited by the average conductivity of the body between the center of charge and a discharge point (finger tip) which is modeled with a 1500 ohm resistor. Now, charge the capacitor up to various voltages up to 15,000 volts and you have a repeatable means for generating antagonistic stresses on some device to be tested for ESD immunity. The machine model is similar but 200 picofarads and 1 ohm of series resistance. I.e., more surface area and better conductivity. Now, what might we think the model would be for a B-747? LOTS of surface area and metallic structure which provides very low series resistance. Static charges between large masses can knock you on your can. Getting back to filling puddle jumpers from gas cans or even fuel trucks . . . The model for a plastic airplane might consider a surface area on the order of 1000 picofarads but what's the series resistance? It's an insulator with hing series resistance. In my studies with ESD testing I discovered that the WORST case instances for testing to human body model (15KV) VERY LITTLE of the potential energy was dissipated at the victim . . . that 1500 ohm resistor dissipates 90 plus % of the energy. When dealing with things like metal airplanes and fuel trucks, the machine models are in force with something on the order of 1000-2000 pf each and VERY LOW series resistance. Connecting them together before dragging out the hose MAY NOT dissipate all their charges to zero . . . but it does bring them TOGETHER in terms of voltage thus ELIMINATING a potential of spark through a low series resistance. I forget the structure of the airplane that started this discussion but I think we were talking about a non-conductive hose fitted to a fuel transfer pump. In this instance, ADDING a low series resistance conductor along the hose length only increases potential for energy dissipation in a spark at the end of the hose. Bringing a potential charge on the airplane and fuel storage containers together is 99.9% of the safety issue. Having a very large series resistance in the potential ignition discharge path is another risk mitigation move. I've been reading lengthy discussions about fuel transfer safety on OBAM aircraft for decades sprinkled with hangar tales and speculative advice . . . but never have I seen a study of the physics that underlie the potential for an ignition accident. Just consider the millions of cars that get fueled by ding-a-ling drivers every day without blowing themselves up. Yes, there are the expected 'news' stories and security camera videos about the occasional filling station fire. Shucks even the Mytbusters made a show out of the notion that cell phones can trigger explosions or fire. But even the hallowed Mythbusters failed to mention the physics . . . much less consider how HARD it is to initiate an explosion under laboratory conditions (re: explosion proofing tests on motors we used to build at Electro-Mech). Bottom line is that if you don't have a means to bring the surface charge of a container to the same potential as the surface of your airplane, then the SAME limitation is in force for causing a spark at the opening of your filler cap. I.e. if you can't get a spark at the connection of a potential equalization wire at the exhaust stack of your engine, you won't get a spark at the filler cap either. Potentials generated by flowing fuel are similarly limited in their ability to conduct the charge to a 'arc gap'. Consider that the fuel is in constant motion so any charge the liquid carries is being continuously dumped into the tank . . . Where is the 'conductor' that's going to bring that charge to an arc gap? Flammable hydrocarbons heavier than gasolines are used as medium for cooling and INSULATOR in high voltage transformers and capacitors. Where does the energy come from, where is it stored, what is the potential equalization path, what is the series resistance of that path, is it possible or even NECESSARY to effect an equalization of potentials at some point AWAY from the filler cap? Bottom line is that using the same care you would exercise in filling your car, boat or lawn mower will suffice to secure your healthy use of that machine. Adding prophylactic features willy-nilly without understanding the physics and design goals may increase risk as opposed to reducing it. If the truth were known as to root cause for the anecdotal fuel transfer fires, most if not all would be due to carelessness. Bob . . .


    Message 6


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    Time: 09:06:07 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: grounding procedures
    At 04:44 AM 7/12/2012, you wrote: ><public@toddheffley.com> > >I was always doubted the importance of using a metal funnel until I >fueled our champ on a dry day with a large plastic funnel. I was >standing in the tire so I was also insulated. A charge built up >strong enough to attract the hair on my arm to stand up toward the >cowl. No Harm, No Foul. It was a warning to alter my behaviour >before a really bad indecent occurred. > >todd Sure, while funnels provide a handy tool for control of the flow of liquid, they add a piece of 'loose gear' to the mix and expose a the surface of liquid flow to the air (and funnel surface). The former increases local concentration of hazardous vapor, the later increases potential for building an electro-static charge (motion of dissimilar materials in close proximity). Your body became yet another surface on which generated charges could collect. A hair-raising experience both literally and for consideration of increased risk. 99.999+ of fuel transfers in the world are effected with a nozzle extend into the fuel storage system. Most are metallic and in contact with each other. The only thing you can do to IMPROVE on this combination would be to close the liquid motion off from the air and potential for spillage by using some feature like I suggested yesterday. As a general rule, I would avoid the use of funnels. Yeah, Lindbergh used 'em . . . even lined the funnel with a chamois to absorb water. We don't read much about aviators of yor setting themselves on fire during a fueling accident but the risks were demonstrably great. Bob . . .


    Message 7


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    Time: 09:26:31 AM PST US
    From: "Ed Anderson" <eanderson@carolina.rr.com>
    Subject: Re: grounding procedures
    I was once fueling my Rv-6A out of "Approved" plastic 5 gallon fuel container. I had a racing funnel with a paper filter cartridge in the center of the spout. It was a 60F low humidity day with no wind. I had done this many times before. This time near the end of the 5 gallon container, I attempted to raise the bottom of the container higher to get the last of the fuel and broke connection between the funnel (also plastic) and the fuel container. There was a "Whomp" of ignition and I found myself with an event on my hands, to wit: 1. Holding a 5 gallon container with flames out its nozzle 2. Holding a large racing funnel with fuel soaked paper filter blazing way. 3. Haven been mildly started by the unexpected ignition event - I had stepped back a pace. This resulting in the funnel I was holding being pulled from the fuel tank leaving me with flames coming out of the aircraft fuel tank, flames on the wing surface where I dragged the emptying funnel from the wing tank opening and flames on the tarmac from that dripping from the wing. The first thought after "oh S...t" was not too panic, after which I quickly 1. Walked approx 15 feet from the aircraft and set down flaming container and funnel. 2. Ran to my Van for my fire extinuisher - always stored under drives seat (could not located it) 3. Raced back to the aircraft and brushed off the surface fuel/fire with a rag. 4. Picked up the wing tank fuel cap and remembered thinking "..this always worked in science class!" ..slapped to fuel cap into the flaming opening -which fortuntately worked just like in highschool science class with test tube and cork. 5. Stomped out the small fire on the tarmac. Fortunately no damage to anything but my nerves and the funnel and container. Even though I had used plastic fuel containers for decades refueling lawnmowers, etc without ever having an incident - I never used anything but metal containers aftewards - however, I was later told that the the breaking of the connection permitted the liquid flow to generated a static potential difference and it would not have mattered if funnel and container had been metal - it was the breaking of the connection that apparently resulting in the conditions that lead to ignition. FWIW Ed From: Robert L. Nuckolls, III Sent: Thursday, July 12, 2012 11:52 AM Subject: Re: AeroElectric-List: grounding procedures At 08:46 PM 7/11/2012, you wrote: soooooooooooo my tanks are grounded to my engine. am i safe to attach a wire from my fuel nozzle to my exhaust pipe or does the wire need to go to the tank filler neck? [that doesn't make sense to me] bob noffs The word "grounded" is poorly understood and in this discussion poorly used. As we've studied in other conversations, having "lots of grounds" can be deleterious to system performance in terms of noised conducted from one system to another. This static charge thing, like most studies of physics is an energy management issue. We have an energy source (motion between dissimilar materials in close proximity), energy storage (capacitance - proportional to surface area of mass carrying a charge), potential pathways for the two masses to exchange levels of charge, series resistance of those pathways, and finally open air gaps in the discharge path were a spark might form that is surrounded by a flammable mixture. The legacy hazard from which all these discussions arise are grounded in the management of charges stored on LARGE surface areas (air transport/military aircraft and fuel trucks or underground fueling systems. BIG numbers in terms of potential energy to be released in that worrisome air-gap. I'll refer readers to a couple of documents I've posted to Aeroelectric.com at http://tinyurl.com/7et4jj5 These two documents speak to 'modeling' the human body for the purposes of carrying out standardized tests for ESD vulnerability. Given the surface area of adult humans to be on the order of 1.5 to 2 square meters, they are 'modeled' as 100 picofarad capacitors. Further the ability to conduct a charge off that 'capacitor' is limited by the average conductivity of the body between the center of charge and a discharge point (finger tip) which is modeled with a 1500 ohm resistor. Now, charge the capacitor up to various voltages up to 15,000 volts and you have a repeatable means for generating antagonistic stresses on some device to be tested for ESD immunity. The machine model is similar but 200 picofarads and 1 ohm of series resistance. I.e., more surface area and better conductivity. Now, what might we think the model would be for a B-747? LOTS of surface area and metallic structure which provides very low series resistance. Static charges between large masses can knock you on your can. Getting back to filling puddle jumpers from gas cans or even fuel trucks . . . The model for a plastic airplane might consider a surface area on the order of 1000 picofarads but what's the series resistance? It's an insulator with hing series resistance. In my studies with ESD testing I discovered that the WORST case instances for testing to human body model (15KV) VERY LITTLE of the potential energy was dissipated at the victim . . . that 1500 ohm resistor dissipates 90 plus % of the energy. When dealing with things like metal airplanes and fuel trucks, the machine models are in force with something on the order of 1000-2000 pf each and VERY LOW series resistance. Connecting them together before dragging out the hose MAY NOT dissipate all their charges to zero . . . but it does bring them TOGETHER in terms of voltage thus ELIMINATING a potential of spark through a low series resistance. I forget the structure of the airplane that started this discussion but I think we were talking about a non-conductive hose fitted to a fuel transfer pump. In this instance, ADDING a low series resistance conductor along the hose length only increases potential for energy dissipation in a spark at the end of the hose. Bringing a potential charge on the airplane and fuel storage containers together is 99.9% of the safety issue. Having a very large series resistance in the potential ignition discharge path is another risk mitigation move. I've been reading lengthy discussions about fuel transfer safety on OBAM aircraft for decades sprinkled with hangar tales and speculative advice . . . but never have I seen a study of the physics that underlie the potential for an ignition accident. Just consider the millions of cars that get fueled by ding-a-ling drivers every day without blowing themselves up. Yes, there are the expected 'news' stories and security camera videos about the occasional filling station fire. Shucks even the Mytbusters made a show out of the notion that cell phones can trigger explosions or fire. But even the hallowed Mythbusters failed to mention the physics . . . much less consider how HARD it is to initiate an explosion under laboratory conditions (re: explosion proofing tests on motors we used to build at Electro-Mech). Bottom line is that if you don't have a means to bring the surface charge of a container to the same potential as the surface of your airplane, then the SAME limitation is in force for causing a spark at the opening of your filler cap. I.e. if you can't get a spark at the connection of a potential equalization wire at the exhaust stack of your engine, you won't get a spark at the filler cap either. Potentials generated by flowing fuel are similarly limited in their ability to conduct the charge to a 'arc gap'. Consider that the fuel is in constant motion so any charge the liquid carries is being continuously dumped into the tank . . . Where is the 'conductor' that's going to bring that charge to an arc gap? Flammable hydrocarbons heavier than gasolines are used as medium for cooling and INSULATOR in high voltage transformers and capacitors. Where does the energy come from, where is it stored, what is the potential equalization path, what is the series resistance of that path, is it possible or even NECESSARY to effect an equalization of potentials at some point AWAY from the filler cap? Bottom line is that using the same care you would exercise in filling your car, boat or lawn mower will suffice to secure your healthy use of that machine. Adding prophylactic features willy-nilly without understanding the physics and design goals may increase risk as opposed to reducing it. If the truth were known as to root cause for the anecdotal fuel transfer fires, most if not all would be due to carelessness. Bob . . . No virus found in this message. Checked by AVG - www.avg.com 07/12/12


    Message 8


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    Time: 10:30:47 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Z12 Alternator Amps
    At 10:21 AM 7/12/2012, you wrote: > >Early this morning I was in the hanger and did some major testing. I >disconnected the 20 Amp Shunt I received originally from B&C when I >got the 20 Amp Aux Alternator. I then temporarily installed a 40 Amp >Shunt I had received from Dynon but had not used. A ground run gave >all the correct and expected indications. The Aux Alternator is now >showing the same Amps as the Main. > >Thanks to everyone who weighed in on this issue. It looks like I >have a solution. This speaks to calibration issues for switching one display between multiple values to be measured, converted to 'amps' and displayed to the operator. A ammeter shunt in simply a power resistor, usually fabricated from manganin (high resistance, low temperature coefficient of resistance). Here's a popular example: [] Two terminals for high current, two SEPARATE terminals for sampling the voltage dropped across the resistance (thin strut between the posts). Shunts are always paired with an instrument. The instrument will display some reading at full scale when excited by a voltage. A legacy convention is to craft ammeters that go to full scale with 50 millivolts applied. Accurate pairing calls for installing a scale plate with an appropriate full scale value (in example below it's 30 Amps; and then combining it with a shunt that drops full scale volts for the instrument when carrying 30 amps). [] When you want to watch two different current flows with a single instrument, you pick two shunts large enough to cover the largest expected current flow . . . but for the display in amps to be accurate, they must be identical shunts. If the two current flows are widely separated (suppose b-lead currents from say a 60A main alternator and an 8A SD-8 alternator), then an ammeter that reads 60+ amps full scale is not so useful for slicing up the output of an 8A alternator. This is often handled by not calibrating the ammeter in AMPs but in PERCENT of full load for the devices being monitored. For example, the ammeter we offer Emacs! Is calibrated in percent. We then offer a variety of shunts calibrated to the instrument and scaled to the load being monitored. For example, an SD-8/60A combo would call for a 10A/60A shunts. An SD-20/40A combo would be 20/40, etc. When you have a digital display like Dynon, it may come to you with a FIXED input sensitivity for full scale, like a steam-gauge . . . It may be programmable either from a local keyboard or USB input. But in any case, it's probably NOT capable of different sensitivities. In the situation we're considering, 40A, 50mv shunts give accurate readings on the Dynon . . . irrespective of the size of the device being monitored. Bob . . .


    Message 9


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    Time: 10:39:59 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: General Aviation Savior??
    At 10:35 AM 7/12/2012, you wrote: > >The following arrived in my Inbox today. I subscribe to a >fascinating tech newsletter Good find. I've subscribed also. Thanks for the heads-up. Bob . . .


    Message 10


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    Time: 10:46:23 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Battery question not aeroplan related
    At 10:48 AM 7/12/2012, you wrote: > >Hello Bob and all, > >as it is not directly aeroplane related I apologize and hope it is >still acceptable to post in that area, at the end it's about >batteries an their differences > >I have an UPS which I neglected a bit and it failed recently; the >batteries in there had an ugly shape but no spill, voltage was >below 2V for each (12v 7.2A nominal) > >I looked now for replacement from Panasonic (using a 17A and now 20A >since years in my plane). Interestingly enough they have two types >of this:] Have you considered automotive batteries for this application? My UPS here has a regular car battery sitting outside the case connected to nice fat wires that extend the leads for a battery normally inside the case. I can get a lot more capacity for less dollars as long as it's not a requirement that the battery 'fit inside'. How old was your original battery? The fact that it failed and changed shape suggests an overcharge condition. What ever your choice of battery, you might want to put a voltmeter on the battery and watch it for a few weeks and in particular after a power-outage event to watch the re-charge event. When all topped off, the battery should be floated at no more than 13.8 volts and no less than 13.0 volts. In other words, too low to allow the battery to be charged and too high to allow the battery to take on 'load'. My UPS battery is about 50A.H. It will keep my desk system up for 5 hours or more. Bob . . .


    Message 11


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    Time: 10:53:22 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: grounding procedures
    Even though I had used plastic fuel containers for decades refueling lawnmowers, etc without ever having an incident - I never used anything but metal containers aftewards - however, I was later told that the the breaking of the connection permitted the liquid flow to generated a static potential difference and it would not have mattered if funnel and container had been metal - it was the breaking of the connection that apparently resulting in the conditions that lead to ignition. Interestingly enough, 'grounding' the airplane would have probably not have changed the outcome. Your particular air/fuel/ignition triad was constituted within a mini-system outside and separate from the airplane itself. Bob . . .


    Message 12


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    Time: 11:10:00 AM PST US
    From: "Bill Bradburry" <bbradburry@bellsouth.net>
    Subject: Re: Z12 Alternator Amps
    Isn't the shunt supposed to be the same as the range on the reading instrument? Bill -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of RV7ASask Sent: Thursday, July 12, 2012 11:21 AM Subject: AeroElectric-List: Re: Z12 Alternator Amps Early this morning I was in the hanger and did some major testing. I disconnected the 20 Amp Shunt I received originally from B&C when I got the 20 Amp Aux Alternator. I then temporarily installed a 40 Amp Shunt I had received from Dynon but had not used. A ground run gave all the correct and expected indications. The Aux Alternator is now showing the same Amps as the Main. Thanks to everyone who weighed in on this issue. It looks like I have a solution. Regards David Lamb Read this topic online here: http://forums.matronics.com/viewtopic.php?p=378099#378099


    Message 13


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    Time: 12:43:33 PM PST US
    From: Bob McCallum <robert.mccallum2@sympatico.ca>
    Subject: Re: Z12 Alternator Amps
    Yes. (or the reading instrument needs to be calibrated to match the shunt. (same thing)) Bob McC > From: bbradburry@bellsouth.net > To: aeroelectric-list@matronics.com > Subject: RE: AeroElectric-List: Re: Z12 Alternator Amps > Date: Thu=2C 12 Jul 2012 14:09:33 -0400 > lsouth.net> > > Isn't the shunt supposed to be the same as the range on the reading > instrument? > > Bill > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of RV7ASa sk > Sent: Thursday=2C July 12=2C 2012 11:21 AM > To: aeroelectric-list@matronics.com > Subject: AeroElectric-List: Re: Z12 Alternator Amps > > > > Early this morning I was in the hanger and did some major testing. I > disconnected the 20 Amp Shunt I received originally from B&C when I got t he > 20 Amp Aux Alternator. I then temporarily installed a 40 Amp Shunt I had > received from Dynon but had not used. A ground run gave all the correct a nd > expected indications. The Aux Alternator is now showing the same Amps as the > Main. > > Thanks to everyone who weighed in on this issue. It looks like I have a > solution. > > Regards > David Lamb > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=378099#378099 > > > > > > > > > > > =========== =========== =========== =========== > > >


    Message 14


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    Time: 12:51:01 PM PST US
    Subject: Re: grounding procedures
    From: Richard Girard <aslsa.rng@gmail.com>
    Bob, I built this rig to fuel my little LSA. I built it mainly to get out of having to bend over and crawl under the wing to fuel, but it also gets me away from where the fuel is flowing. The tubing legs (titanium from Boeing Surplus!) provide grounding although I am going to take advantage of the advice offered here and install a copper wire to pick up any static from fuel flowing through the plastic pipe and run it out to the legs to ground that, too. Using stuff from my strategic supplies and plastic pipe and fittings from Lowe's the whole thing cost less than $10. The other precaution I use during fueling is to always have a size 20 fire extinguisher rated for flammable liquids right next to me. Rick Girard On Thu, Jul 12, 2012 at 11:05 AM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com**> > > > At 04:44 AM 7/12/2012, you wrote: > >> public@toddheffley.com> >> >> I was always doubted the importance of using a metal funnel until I >> fueled our champ on a dry day with a large plastic funnel. I was standing >> in the tire so I was also insulated. A charge built up strong enough to >> attract the hair on my arm to stand up toward the cowl. No Harm, No Foul. >> It was a warning to alter my behaviour before a really bad indecent >> occurred. >> >> todd >> > > > Sure, while funnels provide a handy tool for control > of the flow of liquid, they add a piece of 'loose gear' > to the mix and expose a the surface of liquid flow > to the air (and funnel surface). The former increases > local concentration of hazardous vapor, the later increases > potential for building an electro-static charge (motion > of dissimilar materials in close proximity). Your body > became yet another surface on which generated charges > could collect. A hair-raising experience both literally > and for consideration of increased risk. > > 99.999+ of fuel transfers in the world are effected with > a nozzle extend into the fuel storage system. Most are > metallic and in contact with each other. The only > thing you can do to IMPROVE on this combination would > be to close the liquid motion off from the air and > potential for spillage by using some feature like I > suggested yesterday. > > As a general rule, I would avoid the use of funnels. > Yeah, Lindbergh used 'em . . . even lined the funnel > with a chamois to absorb water. We don't read much > about aviators of yor setting themselves on fire > during a fueling accident but the risks were demonstrably > great. > > > Bob . . . > > -- Zulu Delta Mk IIIC Thanks, Homer GBYM It isn't necessary to have relatives in Kansas City in order to be unhappy. - Groucho Marx


    Message 15


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    Time: 01:48:32 PM PST US
    From: Werner Schneider <glastar@gmx.net>
    Subject: Re: Battery question not aeroplan related
    Thanks Bob, find my answers inside > > Have you considered automotive batteries for this > application? The UPS is rack mounted and uses 4 batteries always 2 in series so I guess I will try tomorrow if I can test with two in series if it works (I've tried already with one but it did not work (I guess it's using 24 V) > > How old was your original battery? The fact that > it failed and changed shape suggests an overcharge > condition. What ever your choice of battery, you > might want to put a voltmeter on the battery and > watch it for a few weeks and in particular after > a power-outage event to watch the re-charge event. They were over 10 years old and I've got some warnings, but as these were LED's only and I had the operation manual not at hand I neglected for several weeks that then caused probably to overload as some cells were dead. Cheers Werner do not archive


    Message 16


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    Time: 02:42:16 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Over-voltage Circuit Trips
    At 06:37 AM 7/11/2012, you wrote: > >Bob N. et al, > >Since my RV first flew about a year ago the over-voltage circuit has >frequently tripped shortly after take off. Resetting the 5 amp >pull-able circuit breaker once or twice generally prevents a >re-occurence for the remainder of the flight but I need to determine >the root cause and correct it. Jack, I'm not ignoring you. Will have a response and some suggestions in the morning . . . Bob . . .


    Message 17


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    Time: 03:36:21 PM PST US
    From: "Jeff Luckey" <JLuckey@pacbell.net>
    Subject: grounding procedures
    Ed, Your story scares the s**t out of me (I wonder if the same happened to you?) but thanks for sharing. After having the advantage of reading about your experience I think I would change the order of operations a little: 1. Before starting refueling operations, make sure fire extinguisher is where I think it is - perhaps even set it nearby on tarmac 2. get rid of flaming container in my hands - keep me from catching on fire 3. replace fuel cap - keep my airplane/fuel tank from continuing to burn 4. go for extinguisher I think this will become my pre-fueling check-list. One thing that I do when fueling from plastic containers is, before I start pouring, touch the airplane (metal airplane) near the fuel cap while holding the full fuel container in the other hand. In my little mind this helps equalize any differences in potential among airframe, fuel container, & me. _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ed Anderson Sent: Thursday, July 12, 2012 09:25 Subject: Re: AeroElectric-List: grounding procedures I was once fueling my Rv-6A out of "Approved" plastic 5 gallon fuel container. I had a racing funnel with a paper filter cartridge in the center of the spout. It was a 60F low humidity day with no wind. I had done this many times before. This time near the end of the 5 gallon container, I attempted to raise the bottom of the container higher to get the last of the fuel and broke connection between the funnel (also plastic) and the fuel container. There was a "Whomp" of ignition and I found myself with an event on my hands, to wit: 1. Holding a 5 gallon container with flames out its nozzle 2. Holding a large racing funnel with fuel soaked paper filter blazing way. 3. Haven been mildly started by the unexpected ignition event - I had stepped back a pace. This resulting in the funnel I was holding being pulled from the fuel tank leaving me with flames coming out of the aircraft fuel tank, flames on the wing surface where I dragged the emptying funnel from the wing tank opening and flames on the tarmac from that dripping from the wing. The first thought after "oh S...t" was not too panic, after which I quickly 1. Walked approx 15 feet from the aircraft and set down flaming container and funnel. 2. Ran to my Van for my fire extinuisher - always stored under drives seat (could not located it) 3. Raced back to the aircraft and brushed off the surface fuel/fire with a rag. 4. Picked up the wing tank fuel cap and remembered thinking "..this always worked in science class!" ..slapped to fuel cap into the flaming opening -which fortuntately worked just like in highschool science class with test tube and cork. 5. Stomped out the small fire on the tarmac. Fortunately no damage to anything but my nerves and the funnel and container. Even though I had used plastic fuel containers for decades refueling lawnmowers, etc without ever having an incident - I never used anything but metal containers aftewards - however, I was later told that the the breaking of the connection permitted the liquid flow to generated a static potential difference and it would not have mattered if funnel and container had been metal - it was the breaking of the connection that apparently resulting in the conditions that lead to ignition. FWIW Ed From: Robert <mailto:nuckolls.bob@aeroelectric.com> L. Nuckolls, III Sent: Thursday, July 12, 2012 11:52 AM Subject: Re: AeroElectric-List: grounding procedures At 08:46 PM 7/11/2012, you wrote: soooooooooooo my tanks are grounded to my engine. am i safe to attach a wire from my fuel nozzle to my exhaust pipe or does the wire need to go to the tank filler neck? [that doesn't make sense to me] bob noffs The word "grounded" is poorly understood and in this discussion poorly used. As we've studied in other conversations, having "lots of grounds" can be deleterious to system performance in terms of noised conducted from one system to another. This static charge thing, like most studies of physics is an energy management issue. We have an energy source (motion between dissimilar materials in close proximity), energy storage (capacitance - proportional to surface area of mass carrying a charge), potential pathways for the two masses to exchange levels of charge, series resistance of those pathways, and finally open air gaps in the discharge path were a spark might form that is surrounded by a flammable mixture. The legacy hazard from which all these discussions arise are grounded in the management of charges stored on LARGE surface areas (air transport/military aircraft and fuel trucks or underground fueling systems. BIG numbers in terms of potential energy to be released in that worrisome air-gap. I'll refer readers to a couple of documents I've posted to Aeroelectric.com at http://tinyurl.com/7et4jj5 These two documents speak to 'modeling' the human body for the purposes of carrying out standardized tests for ESD vulnerability. Given the surface area of adult humans to be on the order of 1.5 to 2 square meters, they are 'modeled' as 100 picofarad capacitors. Further the ability to conduct a charge off that 'capacitor' is limited by the average conductivity of the body between the center of charge and a discharge point (finger tip) which is modeled with a 1500 ohm resistor. Now, charge the capacitor up to various voltages up to 15,000 volts and you have a repeatable means for generating antagonistic stresses on some device to be tested for ESD immunity. The machine model is similar but 200 picofarads and 1 ohm of series resistance. I.e., more surface area and better conductivity. Now, what might we think the model would be for a B-747? LOTS of surface area and metallic structure which provides very low series resistance. Static charges between large masses can knock you on your can. Getting back to filling puddle jumpers from gas cans or even fuel trucks . . . The model for a plastic airplane might consider a surface area on the order of 1000 picofarads but what's the series resistance? It's an insulator with hing series resistance. In my studies with ESD testing I discovered that the WORST case instances for testing to human body model (15KV) VERY LITTLE of the potential energy was dissipated at the victim . . . that 1500 ohm resistor dissipates 90 plus % of the energy. When dealing with things like metal airplanes and fuel trucks, the machine models are in force with something on the order of 1000-2000 pf each and VERY LOW series resistance. Connecting them together before dragging out the hose MAY NOT dissipate all their charges to zero . . . but it does bring them TOGETHER in terms of voltage thus ELIMINATING a potential of spark through a low series resistance. I forget the structure of the airplane that started this discussion but I think we were talking about a non-conductive hose fitted to a fuel transfer pump. In this instance, ADDING a low series resistance conductor along the hose length only increases potential for energy dissipation in a spark at the end of the hose. Bringing a potential charge on the airplane and fuel storage containers together is 99.9% of the safety issue. Having a very large series resistance in the potential ignition discharge path is another risk mitigation move. I've been reading lengthy discussions about fuel transfer safety on OBAM aircraft for decades sprinkled with hangar tales and speculative advice . . . but never have I seen a study of the physics that underlie the potential for an ignition accident. Just consider the millions of cars that get fueled by ding-a-ling drivers every day without blowing themselves up. Yes, there are the expected 'news' stories and security camera videos about the occasional filling station fire. Shucks even the Mytbusters made a show out of the notion that cell phones can trigger explosions or fire. But even the hallowed Mythbusters failed to mention the physics . . . much less consider how HARD it is to initiate an explosion under laboratory conditions (re: explosion proofing tests on motors we used to build at Electro-Mech). Bottom line is that if you don't have a means to bring the surface charge of a container to the same potential as the surface of your airplane, then the SAME limitation is in force for causing a spark at the opening of your filler cap. I.e. if you can't get a spark at the connection of a potential equalization wire at the exhaust stack of your engine, you won't get a spark at the filler cap either. Potentials generated by flowing fuel are similarly limited in their ability to conduct the charge to a 'arc gap'. Consider that the fuel is in constant motion so any charge the liquid carries is being continuously dumped into the tank . . . Where is the 'conductor' that's going to bring that charge to an arc gap? Flammable hydrocarbons heavier than gasolines are used as medium for cooling and INSULATOR in high voltage transformers and capacitors. Where does the energy come from, where is it stored, what is the potential equalization path, what is the series resistance of that path, is it possible or even NECESSARY to effect an equalization of potentials at some point AWAY from the filler cap? Bottom line is that using the same care you would exercise in filling your car, boat or lawn mower will suffice to secure your healthy use of that machine. Adding prophylactic features willy-nilly without understanding the physics and design goals may increase risk as opposed to reducing it. If the truth were known as to root cause for the anecdotal fuel transfer fires, most if not all would be due to carelessness. Bob . . . href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matro nics.com/Navigator?AeroElectric-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c No virus found in this message. Checked by AVG - www.avg.com No virus found in this message. Checked by AVG - www.avg.com


    Message 18


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    Time: 03:56:27 PM PST US
    From: "Ed Anderson" <eanderson@carolina.rr.com>
    Subject: Re: grounding procedures
    I think I did require an underwear check, Jeff. Yes, thinking these things out before hand is certainly the way to do it - coming up with a check list during - is not recommended {:>). Actually, after that, I almost always (99%) either have the fuel truck come out or hook up to an airport type fuel facility. Decided transporting and transferring fuel was something I just did not have to do. It would probably never happened again - but, once is more than enough!!! Ed From: Jeff Luckey Sent: Thursday, July 12, 2012 6:34 PM Subject: RE: AeroElectric-List: grounding procedures Ed, Your story scares the s**t out of me (I wonder if the same happened to you?) but thanks for sharing. After having the advantage of reading about your experience I think I would change the order of operations a little: 1.. Before starting refueling operations, make sure fire extinguisher is where I think it is - perhaps even set it nearby on tarmac 2.. get rid of flaming container in my hands - keep me from catching on fire 3.. replace fuel cap - keep my airplane/fuel tank from continuing to burn 4.. go for extinguisher I think this will become my pre-fueling check-list. One thing that I do when fueling from plastic containers is, before I start pouring, touch the airplane (metal airplane) near the fuel cap while holding the full fuel container in the other hand. In my little mind this helps equalize any differences in potential among airframe, fuel container, & me. ------------------------------------------------------------------------- ------- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ed Anderson Sent: Thursday, July 12, 2012 09:25 Subject: Re: AeroElectric-List: grounding procedures I was once fueling my Rv-6A out of "Approved" plastic 5 gallon fuel container. I had a racing funnel with a paper filter cartridge in the center of the spout. It was a 60F low humidity day with no wind. I had done this many times before. This time near the end of the 5 gallon container, I attempted to raise the bottom of the container higher to get the last of the fuel and broke connection between the funnel (also plastic) and the fuel container. There was a "Whomp" of ignition and I found myself with an event on my hands, to wit: 1. Holding a 5 gallon container with flames out its nozzle 2. Holding a large racing funnel with fuel soaked paper filter blazing way. 3. Haven been mildly started by the unexpected ignition event - I had stepped back a pace. This resulting in the funnel I was holding being pulled from the fuel tank leaving me with flames coming out of the aircraft fuel tank, flames on the wing surface where I dragged the emptying funnel from the wing tank opening and flames on the tarmac from that dripping from the wing. The first thought after "oh S...t" was not too panic, after which I quickly 1. Walked approx 15 feet from the aircraft and set down flaming container and funnel. 2. Ran to my Van for my fire extinuisher - always stored under drives seat (could not located it) 3. Raced back to the aircraft and brushed off the surface fuel/fire with a rag. 4. Picked up the wing tank fuel cap and remembered thinking "..this always worked in science class!" ..slapped to fuel cap into the flaming opening -which fortuntately worked just like in highschool science class with test tube and cork. 5. Stomped out the small fire on the tarmac. Fortunately no damage to anything but my nerves and the funnel and container. Even though I had used plastic fuel containers for decades refueling lawnmowers, etc without ever having an incident - I never used anything but metal containers aftewards - however, I was later told that the the breaking of the connection permitted the liquid flow to generated a static potential difference and it would not have mattered if funnel and container had been metal - it was the breaking of the connection that apparently resulting in the conditions that lead to ignition. FWIW Ed From: Robert L. Nuckolls, III Sent: Thursday, July 12, 2012 11:52 AM Subject: Re: AeroElectric-List: grounding procedures At 08:46 PM 7/11/2012, you wrote: soooooooooooo my tanks are grounded to my engine. am i safe to attach a wire from my fuel nozzle to my exhaust pipe or does the wire need to go to the tank filler neck? [that doesn't make sense to me] bob noffs The word "grounded" is poorly understood and in this discussion poorly used. As we've studied in other conversations, having "lots of grounds" can be deleterious to system performance in terms of noised conducted from one system to another. This static charge thing, like most studies of physics is an energy management issue. We have an energy source (motion between dissimilar materials in close proximity), energy storage (capacitance - proportional to surface area of mass carrying a charge), potential pathways for the two masses to exchange levels of charge, series resistance of those pathways, and finally open air gaps in the discharge path were a spark might form that is surrounded by a flammable mixture. The legacy hazard from which all these discussions arise are grounded in the management of charges stored on LARGE surface areas (air transport/military aircraft and fuel trucks or underground fueling systems. BIG numbers in terms of potential energy to be released in that worrisome air-gap. I'll refer readers to a couple of documents I've posted to Aeroelectric.com at http://tinyurl.com/7et4jj5 These two documents speak to 'modeling' the human body for the purposes of carrying out standardized tests for ESD vulnerability. Given the surface area of adult humans to be on the order of 1.5 to 2 square meters, they are 'modeled' as 100 picofarad capacitors. Further the ability to conduct a charge off that 'capacitor' is limited by the average conductivity of the body between the center of charge and a discharge point (finger tip) which is modeled with a 1500 ohm resistor. Now, charge the capacitor up to various voltages up to 15,000 volts and you have a repeatable means for generating antagonistic stresses on some device to be tested for ESD immunity. The machine model is similar but 200 picofarads and 1 ohm of series resistance. I.e., more surface area and better conductivity. Now, what might we think the model would be for a B-747? LOTS of surface area and metallic structure which provides very low series resistance. Static charges between large masses can knock you on your can. Getting back to filling puddle jumpers from gas cans or even fuel trucks . . . The model for a plastic airplane might consider a surface area on the order of 1000 picofarads but what's the series resistance? It's an insulator with hing series resistance. In my studies with ESD testing I discovered that the WORST case instances for testing to human body model (15KV) VERY LITTLE of the potential energy was dissipated at the victim . . . that 1500 ohm resistor dissipates 90 plus % of the energy. When dealing with things like metal airplanes and fuel trucks, the machine models are in force with something on the order of 1000-2000 pf each and VERY LOW series resistance. Connecting them together before dragging out the hose MAY NOT dissipate all their charges to zero . . . but it does bring them TOGETHER in terms of voltage thus ELIMINATING a potential of spark through a low series resistance. I forget the structure of the airplane that started this discussion but I think we were talking about a non-conductive hose fitted to a fuel transfer pump. In this instance, ADDING a low series resistance conductor along the hose length only increases potential for energy dissipation in a spark at the end of the hose. Bringing a potential charge on the airplane and fuel storage containers together is 99.9% of the safety issue. Having a very large series resistance in the potential ignition discharge path is another risk mitigation move. I've been reading lengthy discussions about fuel transfer safety on OBAM aircraft for decades sprinkled with hangar tales and speculative advice . . . but never have I seen a study of the physics that underlie the potential for an ignition accident. Just consider the millions of cars that get fueled by ding-a-ling drivers every day without blowing themselves up. Yes, there are the expected 'news' stories and security camera videos about the occasional filling station fire. Shucks even the Mytbusters made a show out of the notion that cell phones can trigger explosions or fire. But even the hallowed Mythbusters failed to mention the physics . . . much less consider how HARD it is to initiate an explosion under laboratory conditions (re: explosion proofing tests on motors we used to build at Electro-Mech). Bottom line is that if you don't have a means to bring the surface charge of a container to the same potential as the surface of your airplane, then the SAME limitation is in force for causing a spark at the opening of your filler cap. I.e. if you can't get a spark at the connection of a potential equalization wire at the exhaust stack of your engine, you won't get a spark at the filler cap either. Potentials generated by flowing fuel are similarly limited in their ability to conduct the charge to a 'arc gap'. Consider that the fuel is in constant motion so any charge the liquid carries is being continuously dumped into the tank . . . Where is the 'conductor' that's going to bring that charge to an arc gap? Flammable hydrocarbons heavier than gasolines are used as medium for cooling and INSULATOR in high voltage transformers and capacitors. Where does the energy come from, where is it stored, what is the potential equalization path, what is the series resistance of that path, is it possible or even NECESSARY to effect an equalization of potentials at some point AWAY from the filler cap? Bottom line is that using the same care you would exercise in filling your car, boat or lawn mower will suffice to secure your healthy use of that machine. Adding prophylactic features willy-nilly without understanding the physics and design goals may increase risk as opposed to reducing it. If the truth were known as to root cause for the anecdotal fuel transfer fires, most if not all would be due to carelessness. Bob . . . href="http://www.matronics.com/Navigator?AeroElectric-List">http://www. matronics.com/Navigator?AeroElectric-Listhref="http://forums.matronics. com">http://forums.matronics.comhref="http://www.matronics.com/contribu tion">http://www.matronics.com/cNo virus found in this message. Checked by AVG - www.avg.com 07/12/12 http://www.matronics.com/Navigator?AeroElectric-Listhttp://forums.matroni cs.comhttp://www.matronics.com/contribution No virus found in this message. Checked by AVG - www.avg.com 07/12/12 No virus found in this message. Checked by AVG - www.avg.com 07/12/12




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