---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 01/22/09: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:27 AM - Re: Static wicks (Dale Ellis) 2. 07:50 AM - Re: Static wicks (MICHAEL LARKIN) 3. 10:12 AM - Re: AeroElectric-List Digest: 5 Msgs - 01/21/09 (Jesse Jenks) 4. 01:10 PM - Re: Static wicks (Walter Fellows) 5. 02:48 PM - Re: Will other wiring interfere with Magnetometer? (Allen Fulmer) 6. 03:18 PM - Re: Static wicks (Matt Prather) 7. 04:25 PM - ELT location (James H Nelson) 8. 07:21 PM - Re: ELT location (Ed Holyoke) ________________________________ Message 1 _____________________________________ Time: 06:27:25 AM PST US From: Dale Ellis Subject: Re: AeroElectric-List: Static wicks I flew DeHavilland Dash-8's for nearly 20 years and despite lots and lots of static dissipation & airframe bonding efforts through out (to include lots of static wicks) you could still see St. Elmo's Fire from the prop tips. It took moderate to heavy precipitation for the St. Elmo's Fire to be visible. And then only visible at night. It was neat to see from front end. The passengers seldom saw it because the cabin lights were too bright!! -----Original Message----- >From: "Robert L. Nuckolls, III" >Sent: Jan 22, 2009 12:53 AM >To: aeroelectric-list@matronics.com >Subject: Re: AeroElectric-List: Static wicks > > >At 08:48 AM 1/19/2009, you wrote: >>I have always wondered why (most) certified airplanes have static >>wicks, but not homebuilts? This makes me want to know what their >>actual function is? I was always taught "they dissipate static >>electricity". Is static really that big of an issue, and if so, do >>wicks actually make a difference? I'm building an all metal >>airplane, and so far have not given any thought to control surface >>bonding, or static wicks. >>Thanks. > > When two dissimilar materials slide past each other > rapidly, there is a tendency for electrons to be transferred > from one material to the other . . . usually from > the lesser conductor to the greater conductor. > > Shuffle your feet on the carpet and you can get a > pretty good zap touching a doorknob. Slide out of > your car on a cold dry day and it's not uncommon to > find your body charged with a noteworthy packet of > energy that wakes up your nervous system where the > sparks jump from your bod. > > Airplanes flying in snow, ice particles or even rain > can accumulate a surface charge of excess electrons. > The faster airspeeds and higher particle density > makes the build up stronger. > > If the quantity of excess charge is great enough > AND there's some handy point or edges where the > charges tend to collect, you can SEE the effects > in the form of a luminous hazy discharge along > the edge or at the point. > > On some models of King Airs we used to get reports > of luminous glow around the window frames of glass > fitted with internal de-icing heaters. While the > airplane is shedding excess charge from trailing > edges, antennas, window frames, propeller tips, etc > the phenomenon creates a broadband radio noise that > HAS been strong enough to disable ADF, LORAN, Omega > nav, HF communications and in severe cases, gets the > VHF comm and nav receivers too. > >http://en.wikipedia.org/wiki/St._Elmo%27s_fire > >http://science.howstuffworks.com/st-elmo-fire1.htm > > The big problem we were having with discharges > around the window frames is that it was etching > the glass and in some cases, killing the de-ice > heat sensors. VERY expensive. > > The radio noise comes from the disordered, high density > discharge of an un-treated structure. The cure is > to provide devices that have a propensity for dropping > electrons off into the slip stream. These can be > "wicks" . . . a thing that looks like a fine brush > of copper cat-hairs . . . > >http://www.aircraftspruce.com/catalog/elpages/staticdischrgr.php > > Or an array of tiny points like these: > >http://www.b737.org.uk/wingtips.htm > >http://www.aircraftspruce.com/catalog/elpages/nullfieldtip.php > > This effect is not limited to airplanes. It can > be a significant noise problem on stationary radio > installations when there is blowing snow, dust, rain > or significant convective activity as far away as > 20 miles. > > If you have a sensitive enough ammeter, you can probe > and actually measure this current as cited in > this article. > >http://www.repeater-builder.com/pdf/staticbusterarticlecomplete.pdf > > A number of years ago, Beech did some extensive > testing on the discharge characteristics of various brands > and styles of wicks in the lab. There was a huge difference > in performance of products then offered. I think folks making > these things now are much better at it. > > Doing a GOOD discharger is not a trivial task although > many folks have attempted it. Check out some of the > techniques suggested here: > >http://www.aeroelectric.com/Reference_Docs/Patents/Static_Dissipation/ > > There have been a number of articles and postings to > various forums about how to build your own. I've never > seen an article that actually tested the handy work > on the bench. Given what I witnessed at Beech many moons > ago, I'm convinced that performance of DIY static > wicks is a dart throw without quantified bench marks. > > The same process used to test wicks is use to test the > airplanes probable discharge locations. The airplane is > set up on plastic blocks. A long wand with a spherical > end on it and a pico-ammeter in series is raised up to > about 100,000 volts dc. You can run the wand along the > trailing edges of possible concentration points and > see the ammeter go up when the wand is closest to > a location that would benefit from an effective > discharge wick. > > Wicks are useful only on metal airplanes and then > finding the optimum wick and placement is difficult. > The occurrence of p-static is pretty rare for us > guys who don't fly for a living. > > It won't hurt to have a half dozen wicks on your airplane > but it may not be all that helpful. Wicks have > nothing to do with lightning protection. Bonding > the hinges on an airplane has nothing to do with > mitigation of p-static effects. The idea here is > to avoid welding the hinge rigid in case a lightning > strike attaches to the control surface. > > Here's an short article I did on static-wicks for > an EAA chapter newsletter some years back. > >http://www.eaa326.org/Newsletters/eaa326-3-2005.pdf > > Bob . . . > > ________________________________ Message 2 _____________________________________ Time: 07:50:14 AM PST US From: MICHAEL LARKIN Subject: Re: AeroElectric-List: Static wicks On Airbus jets with all the static wicks they have we still suffer from reduced VHF radio performance in hi P-static environments. On the Lancair airplanes many builders have installed wicks with limited to no improvement to radio performance during high P-static events. Many over time have then removed the wicks. Mike On Jan 22, 2009, at 7:24 AM, Dale Ellis wrote: > > > > I flew DeHavilland Dash-8's for nearly 20 years and despite lots and > lots of static dissipation & airframe bonding efforts through out > (to include lots of static wicks) you could still see St. Elmo's > Fire from the prop tips. It took moderate to heavy precipitation > for the St. Elmo's Fire to be visible. And then only visible at > night. It was neat to see from front end. The passengers seldom > saw it because the cabin lights were too bright!! > > > -----Original Message----- >> From: "Robert L. Nuckolls, III" >> Sent: Jan 22, 2009 12:53 AM >> To: aeroelectric-list@matronics.com >> Subject: Re: AeroElectric-List: Static wicks >> >> > >> >> At 08:48 AM 1/19/2009, you wrote: >>> I have always wondered why (most) certified airplanes have static >>> wicks, but not homebuilts? This makes me want to know what their >>> actual function is? I was always taught "they dissipate static >>> electricity". Is static really that big of an issue, and if so, do >>> wicks actually make a difference? I'm building an all metal >>> airplane, and so far have not given any thought to control surface >>> bonding, or static wicks. >>> Thanks. >> >> When two dissimilar materials slide past each other >> rapidly, there is a tendency for electrons to be transferred >> from one material to the other . . . usually from >> the lesser conductor to the greater conductor. >> >> Shuffle your feet on the carpet and you can get a >> pretty good zap touching a doorknob. Slide out of >> your car on a cold dry day and it's not uncommon to >> find your body charged with a noteworthy packet of >> energy that wakes up your nervous system where the >> sparks jump from your bod. >> >> Airplanes flying in snow, ice particles or even rain >> can accumulate a surface charge of excess electrons. >> The faster airspeeds and higher particle density >> makes the build up stronger. >> >> If the quantity of excess charge is great enough >> AND there's some handy point or edges where the >> charges tend to collect, you can SEE the effects >> in the form of a luminous hazy discharge along >> the edge or at the point. >> >> On some models of King Airs we used to get reports >> of luminous glow around the window frames of glass >> fitted with internal de-icing heaters. While the >> airplane is shedding excess charge from trailing >> edges, antennas, window frames, propeller tips, etc >> the phenomenon creates a broadband radio noise that >> HAS been strong enough to disable ADF, LORAN, Omega >> nav, HF communications and in severe cases, gets the >> VHF comm and nav receivers too. >> >> http://en.wikipedia.org/wiki/St._Elmo%27s_fire >> >> http://science.howstuffworks.com/st-elmo-fire1.htm >> >> The big problem we were having with discharges >> around the window frames is that it was etching >> the glass and in some cases, killing the de-ice >> heat sensors. VERY expensive. >> >> The radio noise comes from the disordered, high density >> discharge of an un-treated structure. The cure is >> to provide devices that have a propensity for dropping >> electrons off into the slip stream. These can be >> "wicks" . . . a thing that looks like a fine brush >> of copper cat-hairs . . . >> >> http://www.aircraftspruce.com/catalog/elpages/staticdischrgr.php >> >> Or an array of tiny points like these: >> >> http://www.b737.org.uk/wingtips.htm >> >> http://www.aircraftspruce.com/catalog/elpages/nullfieldtip.php >> >> This effect is not limited to airplanes. It can >> be a significant noise problem on stationary radio >> installations when there is blowing snow, dust, rain >> or significant convective activity as far away as >> 20 miles. >> >> If you have a sensitive enough ammeter, you can probe >> and actually measure this current as cited in >> this article. >> >> http://www.repeater-builder.com/pdf/staticbusterarticlecomplete.pdf >> >> A number of years ago, Beech did some extensive >> testing on the discharge characteristics of various brands >> and styles of wicks in the lab. There was a huge difference >> in performance of products then offered. I think folks making >> these things now are much better at it. >> >> Doing a GOOD discharger is not a trivial task although >> many folks have attempted it. Check out some of the >> techniques suggested here: >> >> http://www.aeroelectric.com/Reference_Docs/Patents/ >> Static_Dissipation/ >> >> There have been a number of articles and postings to >> various forums about how to build your own. I've never >> seen an article that actually tested the handy work >> on the bench. Given what I witnessed at Beech many moons >> ago, I'm convinced that performance of DIY static >> wicks is a dart throw without quantified bench marks. >> >> The same process used to test wicks is use to test the >> airplanes probable discharge locations. The airplane is >> set up on plastic blocks. A long wand with a spherical >> end on it and a pico-ammeter in series is raised up to >> about 100,000 volts dc. You can run the wand along the >> trailing edges of possible concentration points and >> see the ammeter go up when the wand is closest to >> a location that would benefit from an effective >> discharge wick. >> >> Wicks are useful only on metal airplanes and then >> finding the optimum wick and placement is difficult. >> The occurrence of p-static is pretty rare for us >> guys who don't fly for a living. >> >> It won't hurt to have a half dozen wicks on your airplane >> but it may not be all that helpful. Wicks have >> nothing to do with lightning protection. Bonding >> the hinges on an airplane has nothing to do with >> mitigation of p-static effects. The idea here is >> to avoid welding the hinge rigid in case a lightning >> strike attaches to the control surface. >> >> Here's an short article I did on static-wicks for >> an EAA chapter newsletter some years back. >> >> http://www.eaa326.org/Newsletters/eaa326-3-2005.pdf >> >> Bob . . . >> >> >> >> >> > > ________________________________ Message 3 _____________________________________ Time: 10:12:40 AM PST US From: Jesse Jenks Subject: AeroElectric-List: RE: AeroElectric-List Digest: 5 Msgs - 01/21/09 Bob=2C Thanks for the detailed reply. I guess I should have searched your website before asking that question. It's funny=2C I've been flying for a living for about 15 years and never knew the real reason for bonding. I only knew that if I missed a broken bonding strap on a preflight I would get busted by the man. I could never understand why things like landing gear doors are bonded. Makes sense now. Thanks. "Bonding the hinges on an airplane has nothing to do with mitigation of p-static effects. The idea here is to avoid welding the hinge rigid in case a lightning strike attaches to the control surface." _________________________________________________________________ Hotmail=AE goes where you go. On a PC=2C on the Web=2C on your phone. http://www.windowslive-hotmail.com/learnmore/versatility.aspx#mobile?ocid =TXT_TAGHM_WL_HM_versatility_121208 ________________________________ Message 4 _____________________________________ Time: 01:10:50 PM PST US Subject: Re: AeroElectric-List: Static wicks From: Walter Fellows On a plastic airplane, if the composite parts are made with a specialized copper or aluminum mesh in the first layer of the mold, the parts of the airplane can be bonded together and static wicks added to give the same p-static bleed as an aluminum airplane (this the major part - without the wicks - of a program to provide lightning protection in composite aircraft). However there are weather conditions that will overwhelm the system even in an aluminum airplane, I had my HSI spinning and a loss of VHF reception (while retaining VHF transmission ability) over Lake Michigan at night in a Cessna 210 due to p-static apparently caused by almost invisible ice crystals in the air. I was IFR at the time and inadvertently stepping on center trying to restablish communcation much to their annoyance. On Thu, Jan 22, 2009 at 7:44 AM, MICHAEL LARKIN wrote: > > > On Airbus jets with all the static wicks they have we still suffer from > reduced VHF radio performance in hi P-static environments. On the Lancair > airplanes many builders have installed wicks with limited to no improvement > to radio performance during high P-static events. Many over time have then > removed the wicks. > > Mike > > > On Jan 22, 2009, at 7:24 AM, Dale Ellis wrote: > >> rv8builder@earthlink.net> >> >> I flew DeHavilland Dash-8's for nearly 20 years and despite lots and lots >> of static dissipation & airframe bonding efforts through out (to include >> lots of static wicks) you could still see St. Elmo's Fire from the prop >> tips. It took moderate to heavy precipitation for the St. Elmo's Fire to be >> visible. And then only visible at night. It was neat to see from front >> end. The passengers seldom saw it because the cabin lights were too >> bright!! >> >> >> -----Original Message----- >> >>> From: "Robert L. Nuckolls, III" >>> Sent: Jan 22, 2009 12:53 AM >>> To: aeroelectric-list@matronics.com >>> Subject: Re: AeroElectric-List: Static wicks >>> >>> nuckolls.bob@aeroelectric.com> >>> >>> At 08:48 AM 1/19/2009, you wrote: >>> >>>> I have always wondered why (most) certified airplanes have static >>>> wicks, but not homebuilts? This makes me want to know what their >>>> actual function is? I was always taught "they dissipate static >>>> electricity". Is static really that big of an issue, and if so, do >>>> wicks actually make a difference? I'm building an all metal >>>> airplane, and so far have not given any thought to control surface >>>> bonding, or static wicks. >>>> Thanks. >>>> >>> >>> When two dissimilar materials slide past each other >>> rapidly, there is a tendency for electrons to be transferred >>> from one material to the other . . . usually from >>> the lesser conductor to the greater conductor. >>> >>> Shuffle your feet on the carpet and you can get a >>> pretty good zap touching a doorknob. Slide out of >>> your car on a cold dry day and it's not uncommon to >>> find your body charged with a noteworthy packet of >>> energy that wakes up your nervous system where the >>> sparks jump from your bod. >>> >>> Airplanes flying in snow, ice particles or even rain >>> can accumulate a surface charge of excess electrons. >>> The faster airspeeds and higher particle density >>> makes the build up stronger. >>> >>> If the quantity of excess charge is great enough >>> AND there's some handy point or edges where the >>> charges tend to collect, you can SEE the effects >>> in the form of a luminous hazy discharge along >>> the edge or at the point. >>> >>> On some models of King Airs we used to get reports >>> of luminous glow around the window frames of glass >>> fitted with internal de-icing heaters. While the >>> airplane is shedding excess charge from trailing >>> edges, antennas, window frames, propeller tips, etc >>> the phenomenon creates a broadband radio noise that >>> HAS been strong enough to disable ADF, LORAN, Omega >>> nav, HF communications and in severe cases, gets the >>> VHF comm and nav receivers too. >>> >>> http://en.wikipedia.org/wiki/St._Elmo%27s_fire >>> >>> http://science.howstuffworks.com/st-elmo-fire1.htm >>> >>> The big problem we were having with discharges >>> around the window frames is that it was etching >>> the glass and in some cases, killing the de-ice >>> heat sensors. VERY expensive. >>> >>> The radio noise comes from the disordered, high density >>> discharge of an un-treated structure. The cure is >>> to provide devices that have a propensity for dropping >>> electrons off into the slip stream. These can be >>> "wicks" . . . a thing that looks like a fine brush >>> of copper cat-hairs . . . >>> >>> http://www.aircraftspruce.com/catalog/elpages/staticdischrgr.php >>> >>> Or an array of tiny points like these: >>> >>> http://www.b737.org.uk/wingtips.htm >>> >>> http://www.aircraftspruce.com/catalog/elpages/nullfieldtip.php >>> >>> This effect is not limited to airplanes. It can >>> be a significant noise problem on stationary radio >>> installations when there is blowing snow, dust, rain >>> or significant convective activity as far away as >>> 20 miles. >>> >>> If you have a sensitive enough ammeter, you can probe >>> and actually measure this current as cited in >>> this article. >>> >>> http://www.repeater-builder.com/pdf/staticbusterarticlecomplete.pdf >>> >>> A number of years ago, Beech did some extensive >>> testing on the discharge characteristics of various brands >>> and styles of wicks in the lab. There was a huge difference >>> in performance of products then offered. I think folks making >>> these things now are much better at it. >>> >>> Doing a GOOD discharger is not a trivial task although >>> many folks have attempted it. Check out some of the >>> techniques suggested here: >>> >>> http://www.aeroelectric.com/Reference_Docs/Patents/Static_Dissipation/ >>> >>> There have been a number of articles and postings to >>> various forums about how to build your own. I've never >>> seen an article that actually tested the handy work >>> on the bench. Given what I witnessed at Beech many moons >>> ago, I'm convinced that performance of DIY static >>> wicks is a dart throw without quantified bench marks. >>> >>> The same process used to test wicks is use to test the >>> airplanes probable discharge locations. The airplane is >>> set up on plastic blocks. A long wand with a spherical >>> end on it and a pico-ammeter in series is raised up to >>> about 100,000 volts dc. You can run the wand along the >>> trailing edges of possible concentration points and >>> see the ammeter go up when the wand is closest to >>> a location that would benefit from an effective >>> discharge wick. >>> >>> Wicks are useful only on metal airplanes and then >>> finding the optimum wick and placement is difficult. >>> The occurrence of p-static is pretty rare for us >>> guys who don't fly for a living. >>> >>> It won't hurt to have a half dozen wicks on your airplane >>> but it may not be all that helpful. Wicks have >>> nothing to do with lightning protection. Bonding >>> the hinges on an airplane has nothing to do with >>> mitigation of p-static effects. The idea here is >>> to avoid welding the hinge rigid in case a lightning >>> strike attaches to the control surface. >>> >>> Here's an short article I did on static-wicks for >>> an EAA chapter newsletter some years back. >>> >>> http://www.eaa326.org/Newsletters/eaa326-3-2005.pdf >>> >>> Bob . . . >>> >>> >>> >>> >>> >>> >> >> >> >> >> > > ________________________________ Message 5 _____________________________________ Time: 02:48:32 PM PST US From: "Allen Fulmer" Subject: RE: AeroElectric-List: Will other wiring interfere with Magnetometer? Getting ready to pull a twisted pair from panel to position lights in tips. I was measuring for how long to cut the wires and I had a couple of questions: Does the pair of wires feeding each nav light need to be twisted the entire length from panel to light or just some distance before and after as it passes the magnetometer? And since my leading edge landing/taxi lights (located several feet inboard) will be grounded locally can I shorten the length of the nav light ground wire and ground to the airframe at the same place? And then twist from there to the nav light? Thanks, Allen Fulmer >>>-----Original Message----- >>>From: owner-aeroelectric-list-server@matronics.com >>>[mailto:owner-aeroelectric-list-server@matronics.com]On >>>Behalf Of Peter >>>Pengilly >>>Sent: Tuesday, January 06, 2009 12:35 PM >>>To: aeroelectric-list@matronics.com >>>Subject: RE: AeroElectric-List: Will other wiring interfere with >>>Magnetometer? >>> >>> >>> >>> >>>Allen, >>> >>>A few years ago I worked on an airplane that was the first >>>of type to have a >>>magnetic anomaly detector in the fuselage. The thing could cope with >>>constant magnetic fields - that is circuits that were always >>>on or off, but >>>not with variable ones. We learnt that shielded wires have >>>no effect on the >>>magnetic influence of current carrier, and that a simple >>>twisted pair is by >>>far better (I think the reason why was explained on the list >>>a week or two >>>ago). So don't bother with the shielded wire, just twist up >>>a pair of 22g >>>wires yourself - something like 5 to 10 twists per foot >>>should be adequate. >>> >>>Peter >>> >>>-----Original Message----- >>>From: owner-aeroelectric-list-server@matronics.com >>>[mailto:owner-aeroelectric-list-server@matronics.com] On >>>Behalf Of Allen >>>Fulmer >>>Sent: 06 January 2009 18:05 >>>To: aeroelectric-list@matronics.com >>>Subject: RE: AeroElectric-List: Will other wiring interfere with >>>Magnetometer? >>> >>> >>> >>>Thank you, Bob! >>> >>>That will be easy to do now as I am just pulling wires. >>> >>>Stein Air has a two conductor shielded cable: MIL-27500 >>>Tefzel AWG22 - 2 >>>Conductor Shielded Cable >>> >>>Would this be "the best" even if a little more expensive? >>>(LED Nav lights >>>only draw .3 amp or so per wing.) >>> >>>And if shielded is fine then ground one end of the shield at >>>forest of tabs >>>on firewall? >>> >>>Thanks again for all you do for us. >>> >>>Allen Fulmer >>> >>>>>>-----Original Message----- >>>>>>From: owner-aeroelectric-list-server@matronics.com >>>>>>[mailto:owner-aeroelectric-list-server@matronics.com]On >>>>>>Behalf Of Robert >>>>>>L. Nuckolls, III >>>>>>Sent: Tuesday, January 06, 2009 9:26 AM >>>>>>To: aeroelectric-list@matronics.com >>>>>>Subject: RE: AeroElectric-List: Will other wiring interfere with >>>>>>Magnetometer? >>>>>> >>>>>> >>>>>>Nuckolls, III" >>>>>> >>>>>>At 07:49 AM 1/6/2009, you wrote: >>>>>> >>>>>>> >>>>>>>Okay, so it would be okay to run all the wires and cables >>>>>>thorough the same >>>>>>>conduit but the current carrying ones "(such as navigation >>>>>>or landing light >>>>>>>wires)" would still need to pass at least 12" from the >>>magnetometer. >>>>>>> >>>>>>>With the magnetometer 18" forward of the rear spar (and >>>>>>thus the aileron >>>>>>>steel mass balance tube) the wires for Nav and strobes will >>>>>>have to be >>>>>>>routed 12" forward of that on their way to forward end of >>>>>>wingtip. That >>>>>>>should be consistent with Bob Archer's antenna design. >>>>>> >>>>>> >>>>>> Magnetometer installation is a good example of >>>>>> a case where careful paralleling and perhaps >>>>>> twisting of outbound/return current paths as they >>>>>> pass by the magnetometer. I had a builder who >>>>>> reported a compass swing of several degrees when >>>>>> he turned on nav lights. Seems he grounded the lamp >>>>>> locally and had a single power lead running only >>>>>> a few inches from the remote compass sensor. >>>>>> >>>>>> He fixed the problem by running a twisted pair >>>>>> for power and ground past the compass sensor. >>>>>> Strobe and antenna wiring generally have no risk >>>>>> to magnetometer calibration. >>>>>> >>>>>> Only those bundles/wires with significant unidirectional >>>>>> DC currents flowing in them have a potential for >>>>>> problems. Of course, DISTANCE is also a strong >>>>>> attenuator of magnetic effects. I forget the >>>>>> exact relationship but I'm thinking that effects >>>>>> of a wire at 1" are reduced by a factor of more >>>>>> than 100 at 10". >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> Bob . . . >>>>>> >>>>>> ----------------------------------------) >>>>>> ( . . . a long habit of not thinking ) >>>>>> ( a thing wrong, gives it a superficial ) >>>>>> ( appearance of being right . . . ) >>>>>> ( ) >>>>>> ( -Thomas Paine 1776- ) >>>>>> ---------------------------------------- >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> ________________________________ Message 6 _____________________________________ Time: 03:18:01 PM PST US Subject: Re: AeroElectric-List: Static wicks From: "Matt Prather" An aside: Bob Buck, author of "Weather Flying" flew many research missions during and after WWII with the specific purpose of understanding P-static and testing equipment designed to alleviate its effects on aircraft systems. His discussion of this in his autobiography ("North Star Over My Shoulder") is quite interesting. There is also anecdotal information that suggests that electrical bonding of control surfaces to the airframe can alleviate certain p-static effects. Apparently the charge that builds up on the body of the airframe doesn't always readily pass through the hinges and control mechanisms to control surfaces. A small charge builds up between the control surface and what it's mounted to, and then bleeds off in small discharges. Each discharge radiates a small amount of electrical noise which can apparently interfere with the function of some equipment. The story about this that I read was one about a shipboard tactical Navy aircraft which suffered poor nav system performance without the control surface bonding. Again, this is anecdotal.. Regards, Matt- > On a plastic airplane, if the composite parts are made with a specialized > copper or aluminum mesh in the first layer of the mold, the parts of the > airplane can be bonded together and static wicks added to give the same > p-static bleed as an aluminum airplane (this the major part - without the > wicks - of a program to provide lightning protection in composite > aircraft). > However there are weather conditions that will overwhelm the system even > in > an aluminum airplane, I had my HSI spinning and a loss of VHF reception > (while retaining VHF transmission ability) over Lake Michigan at night in > a > Cessna 210 due to p-static apparently caused by almost invisible ice > crystals in the air. I was IFR at the time and inadvertently stepping on > center trying to restablish communcation much to their annoyance. > > On Thu, Jan 22, 2009 at 7:44 AM, MICHAEL LARKIN wrote: > >> >> >> >> On Airbus jets with all the static wicks they have we still suffer from >> reduced VHF radio performance in hi P-static environments. On the >> Lancair >> airplanes many builders have installed wicks with limited to no >> improvement >> to radio performance during high P-static events. Many over time have >> then >> removed the wicks. >> >> Mike >> >> >> >> >> On Jan 22, 2009, at 7:24 AM, Dale Ellis wrote: >> >>> rv8builder@earthlink.net> >>> >>> I flew DeHavilland Dash-8's for nearly 20 years and despite lots and >>> lots >>> of static dissipation & airframe bonding efforts through out (to >>> include >>> lots of static wicks) you could still see St. Elmo's Fire from the prop >>> tips. It took moderate to heavy precipitation for the St. Elmo's Fire >>> to be >>> visible. And then only visible at night. It was neat to see from >>> front >>> end. The passengers seldom saw it because the cabin lights were too >>> bright!! >>> >>> >>> -----Original Message----- >>> >>>> From: "Robert L. Nuckolls, III" >>>> Sent: Jan 22, 2009 12:53 AM >>>> To: aeroelectric-list@matronics.com >>>> Subject: Re: AeroElectric-List: Static wicks >>>> >>>> nuckolls.bob@aeroelectric.com> >>>> >>>> At 08:48 AM 1/19/2009, you wrote: >>>> >>>>> I have always wondered why (most) certified airplanes have static >>>>> wicks, but not homebuilts? This makes me want to know what their >>>>> actual function is? I was always taught "they dissipate static >>>>> electricity". Is static really that big of an issue, and if so, do >>>>> wicks actually make a difference? I'm building an all metal >>>>> airplane, and so far have not given any thought to control surface >>>>> bonding, or static wicks. >>>>> Thanks. >>>>> >>>> >>>> When two dissimilar materials slide past each other >>>> rapidly, there is a tendency for electrons to be transferred >>>> from one material to the other . . . usually from >>>> the lesser conductor to the greater conductor. >>>> >>>> Shuffle your feet on the carpet and you can get a >>>> pretty good zap touching a doorknob. Slide out of >>>> your car on a cold dry day and it's not uncommon to >>>> find your body charged with a noteworthy packet of >>>> energy that wakes up your nervous system where the >>>> sparks jump from your bod. >>>> >>>> Airplanes flying in snow, ice particles or even rain >>>> can accumulate a surface charge of excess electrons. >>>> The faster airspeeds and higher particle density >>>> makes the build up stronger. >>>> >>>> If the quantity of excess charge is great enough >>>> AND there's some handy point or edges where the >>>> charges tend to collect, you can SEE the effects >>>> in the form of a luminous hazy discharge along >>>> the edge or at the point. >>>> >>>> On some models of King Airs we used to get reports >>>> of luminous glow around the window frames of glass >>>> fitted with internal de-icing heaters. While the >>>> airplane is shedding excess charge from trailing >>>> edges, antennas, window frames, propeller tips, etc >>>> the phenomenon creates a broadband radio noise that >>>> HAS been strong enough to disable ADF, LORAN, Omega >>>> nav, HF communications and in severe cases, gets the >>>> VHF comm and nav receivers too. >>>> >>>> http://en.wikipedia.org/wiki/St._Elmo%27s_fire >>>> >>>> http://science.howstuffworks.com/st-elmo-fire1.htm >>>> >>>> The big problem we were having with discharges >>>> around the window frames is that it was etching >>>> the glass and in some cases, killing the de-ice >>>> heat sensors. VERY expensive. >>>> >>>> The radio noise comes from the disordered, high density >>>> discharge of an un-treated structure. The cure is >>>> to provide devices that have a propensity for dropping >>>> electrons off into the slip stream. These can be >>>> "wicks" . . . a thing that looks like a fine brush >>>> of copper cat-hairs . . . >>>> >>>> http://www.aircraftspruce.com/catalog/elpages/staticdischrgr.php >>>> >>>> Or an array of tiny points like these: >>>> >>>> http://www.b737.org.uk/wingtips.htm >>>> >>>> http://www.aircraftspruce.com/catalog/elpages/nullfieldtip.php >>>> >>>> This effect is not limited to airplanes. It can >>>> be a significant noise problem on stationary radio >>>> installations when there is blowing snow, dust, rain >>>> or significant convective activity as far away as >>>> 20 miles. >>>> >>>> If you have a sensitive enough ammeter, you can probe >>>> and actually measure this current as cited in >>>> this article. >>>> >>>> http://www.repeater-builder.com/pdf/staticbusterarticlecomplete.pdf >>>> >>>> A number of years ago, Beech did some extensive >>>> testing on the discharge characteristics of various brands >>>> and styles of wicks in the lab. There was a huge difference >>>> in performance of products then offered. I think folks making >>>> these things now are much better at it. >>>> >>>> Doing a GOOD discharger is not a trivial task although >>>> many folks have attempted it. Check out some of the >>>> techniques suggested here: >>>> >>>> http://www.aeroelectric.com/Reference_Docs/Patents/Static_Dissipation/ >>>> >>>> There have been a number of articles and postings to >>>> various forums about how to build your own. I've never >>>> seen an article that actually tested the handy work >>>> on the bench. Given what I witnessed at Beech many moons >>>> ago, I'm convinced that performance of DIY static >>>> wicks is a dart throw without quantified bench marks. >>>> >>>> The same process used to test wicks is use to test the >>>> airplanes probable discharge locations. The airplane is >>>> set up on plastic blocks. A long wand with a spherical >>>> end on it and a pico-ammeter in series is raised up to >>>> about 100,000 volts dc. You can run the wand along the >>>> trailing edges of possible concentration points and >>>> see the ammeter go up when the wand is closest to >>>> a location that would benefit from an effective >>>> discharge wick. >>>> >>>> Wicks are useful only on metal airplanes and then >>>> finding the optimum wick and placement is difficult. >>>> The occurrence of p-static is pretty rare for us >>>> guys who don't fly for a living. >>>> >>>> It won't hurt to have a half dozen wicks on your airplane >>>> but it may not be all that helpful. Wicks have >>>> nothing to do with lightning protection. Bonding >>>> the hinges on an airplane has nothing to do with >>>> mitigation of p-static effects. The idea here is >>>> to avoid welding the hinge rigid in case a lightning >>>> strike attaches to the control surface. >>>> >>>> Here's an short article I did on static-wicks for >>>> an EAA chapter newsletter some years back. >>>> >>>> http://www.eaa326.org/Newsletters/eaa326-3-2005.pdf >>>> >>>> Bob . . . >>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >> >> >> >> >> > ________________________________ Message 7 _____________________________________ Time: 04:25:02 PM PST US Subject: AeroElectric-List: ELT location From: James H Nelson Hi Ed, Shoot, I'll have to look at it. My last bird mounted it the same way (switches forward) but it was a different mfg. I assumed (bad me) that the orientation would be the same. I don't have a lot of reason to believe that this unit will be of any help. Its there for the DAR and regulations. That is why I bought a PLB with GPS. If I'm alive, I will remove it from my survival vest and turn it on. Even if I'm upside down, I will break the canopy and stick my arm outside and run it. As a note, I have a survival vest that I got from the U.S. Army during my 32 years with them flying helicopters. It has a good survival knife, pocket for a survival radio (my PLB) and lots of other neat stuff to keep you alive for a while. A good fishing vest with pockets all over will do the same thing. I should weigh it to see what it weighs as I think it is around 7# =/- a pound or two. Thanks again for the heads up. Jim ____________________________________________________________ Click for free info on college degrees. http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw1U6R6KubryOwbqqIvdia8uuNezTxsmslPHQHES9IEeUMJwV/ ________________________________ Message 8 _____________________________________ Time: 07:21:26 PM PST US From: Ed Holyoke Subject: Re: AeroElectric-List: ELT location Howdy Jim, Yeah, the switches should be forward, but there is a side (the wide one) which is supposed to face down. You're right, it probably won't save your life no matter how you mount it, but you do have to get it signed off. ;-) Good luck with it. Pax, Ed James H Nelson wrote: > > Hi Ed, > Shoot, I'll have to look at it. My last bird mounted it the same > way (switches forward) but it was a different mfg. I assumed (bad me) > that the orientation would be the same. I don't have a lot of reason to > believe that this unit will be of any help. Its there for the DAR and > regulations. That is why I bought a PLB with GPS. If I'm alive, I will > remove it from my survival vest and turn it on. Even if I'm upside down, > I will break the canopy and stick my arm outside and run it. As a note, > I have a survival vest that I got from the U.S. Army during my 32 years > with them flying helicopters. It has a good survival knife, pocket for a > survival radio (my PLB) and lots of other neat stuff to keep you alive > for a while. A good fishing vest with pockets all over will do the same > thing. I should weigh it to see what it weighs as I think it is around 7# > =/- a pound or two. > Thanks again for the heads up. > > Jim > ____________________________________________________________ > Click for free info on college degrees. > http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw1U6R6KubryOwbqqIvdia8uuNezTxsmslPHQHES9IEeUMJwV/ > > > ------------------------------------------------------------------------------------- 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.