Today's Message Index:
----------------------
1. 10:30 AM - Re: AeroElectric-List Digest: 14 Msgs - 01/19/09 (Jesse Jenks)
2. 03:34 PM - Re: Re: AeroElectric-List Digest: 14 Msgs - 01/19/09 (BobsV35B@aol.com)
3. 07:10 PM - Re: Wig Wag system (Sully)
4. 08:05 PM - Re: Wig Wag system (marcausman)
5. 09:58 PM - Re: Static wicks (Robert L. Nuckolls, III)
Message 1
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| Subject: | RE: AeroElectric-List Digest: 14 Msgs - 01/19/09 |
Thanks guys. You both seem to be saying that bonding is important=2C and st
atic wicks not so much. Just wondering why bonding?
Jesse
> Time: 07:31:39 AM PST US
> From: Harley <harley@AgelessWings.com>
> Subject: Re: AeroElectric-List: Static wicks
>
> They can work to dissipate static if they are attached to a conducting
> surface. That way=2C they can bypass whatever is creating the static and
> insulating the object from a normal ground (like the plastic or rubber
> tires on a fork lift).
>
> But on many homebuilts=2C the plane is made of non conducting materials
> (wood and fabric or fiberglass and/or epoxy)=2C and a static wick will
> only discharge the point that it is attached. A couple of inches away
> from that point=2C the charge remains as strong as ever.
>
> I had many a discussion with fork lift drivers at Pennwalt when they
> would attach a static wick to the plastic part of the frame on the truck
> (it was easier to drill a hole into)=2C and then complain that they still
> got zapped when they stepped off the truck. For those that really
> thought they needed it=2C we would attach the wicks to the metal frame
> under the truck. But=2C that often didn't help either=2C because the wick
> was often dragging on a non conducting surface (epoxy sealed floors).
> Also=2C the line operators used vacuum cleaners to pick up the spilled
> foot powder...even though they used a so-called static proof hose (it
> had a grounded wire spiraling along the length of it) they would still
> get zapped when they put the hose down. The charge was decreased=2C
> because of the presence of the wire=2C but still built up on the hose
> between the wire coil wraps.
>
> In short=2C you need a continuous conductive path to discharge a static
> charge. From every area where the charge can build.
>
> Harley
> ------------------------------------------------------------------------
>
>
> Jesse Jenks wrote:
> > I have always wondered why (most) certified airplanes have static
> > wicks=2C 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=2C and if so=2C do
> > wicks actually make a difference? I'm building an all metal airplane=2C
> > and so far have not given any thought to control surface bonding=2C or
> > static wicks.
> > Thanks.
> Time: 09:23:39 AM PST US
> From: BobsV35B@aol.com
> Subject: Re: AeroElectric-List: Static wicks
>
> Good Morning Jesse=2C
>
> I have almost no experience in homebuilt aircraft=2C but I do have severa
l
> thousand hours in aircraft that were equipped with static wicks and sever
al
> thousand hours in aircraft with no static wicks applied.
>
> My suggestion would be to thoroughly bond all control surfaces=2C flaps
> included=2C but not bother with static wicks unless you note a problem.
>
> The static problem was greater in the days of low frequency radio. It was
> not at all uncommon to lose all communication capability when we were usi
ng the
>
> HF transmitters and receiving on low frequency. I have encountered
> precipitation static strong enough to knock out VHF communications for j
ust a
> very few
> minutes=2C but that has never lasted more than four or five minutes.
>
> I have also experienced static discharges=2C but that has always been on
> aircraft that were equipped with static wicks. There is no doubt that I h
ave flown
>
> in much heavier precipitation in static wick equipped airplanes than I h
ave
> in airplanes that are not so equipped=2C but I have flown both in some ra
ther
> severe situations.
>
> Wait and see if you have a problem.
>
> If you lose VHF navigation capability in a heavy thunderstorm=2C you may
want
> to add static wicks or you may just decide to stay out of such conditions
!
>
> In any case=2C I have never seen a GPS signal affected by any static buil
d up.
>
> The only time I would suggest using static wicks is if your only means of
> navigation is a LORAN. Even then=2C you don't need it if you stay out of
> precipitation.
>
> Summary? Bonding YES=2C Static Wicks? NO
>
> Happy Skies
>
> Old Bob
> AKA
> Bob Siegfried
> Ancient Aviator
> 628 West 86th Street
> Downers Grove=2C IL 60516
> 630 985-8502
> Stearman N3977A
> Brookeridge Air Park LL22
>
>
> In a message dated 1/19/2009 8:52:32 A.M. Central Standard Time=2C
> jessejenks@hotmail.com writes:
>
> I have always wondered why (most) certified airplanes have static wicks
=2C 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=2C and if so=2C do wicks actually make a difference? I'm
building
>
> an all metal airplane=2C and so far have not given any thought to contro
l
> surface bonding=2C or static wicks.
> Thanks.
>
_________________________________________________________________
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Message 2
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| Subject: | Re: RE: AeroElectric-List Digest: 14 Msgs - 01/19/09 |
Good Afternoon Jesse,
Bonding is easy, cheap, and light weight.
It will probably do some good. In any precipitation at all, different
potentials will be built up on isolated components. If all of those isolated
components are joined by grounding or bonding straps, any precipitation static
that
is produced will be minimized and most of it will be shed off the sharp
edges of the tail feathers or the ailerons. If you add the static wicks, they
will shed the static even better, but the static wicks are heavy, expensive and
the most effective ones are so dangerous to personnel that they are generally
removed when the airplane is not flying. I don't know if bonding mitigates
ten percent of the static or ninety percent of the static, but it is extremely
cost effective.
Happy Skies
Old Bob
AKA
Bob Siegfried
Ancient Aviator
628 West 86th Street
Downers Grove, IL 60516
630 985-8502
Stearman N3977A
Brookeridge Air Park LL22
In a message dated 1/21/2009 12:32:47 P.M. Central Standard Time,
jessejenks@hotmail.com writes:
Thanks guys. You both seem to be saying that bonding is important, and
static wicks not so much. Just wondering why bonding?
Jesse
**************A Good Credit Score is 700 or Above. See yours in just 2 easy
steps!
cemailfooterNO62)
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| Subject: | Re: Wig Wag system |
Marc,
Will the VP-200 wig wag HID lights?
--------
Sully
RV-7 In-work
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=226113#226113
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| Subject: | Re: Wig Wag system |
Yes, HID lights need a warm-up period then you can begin wig-wag. The warm up and
transition to wig-wag is all automatic.
This feature is coming in the next software release, about mid-year 2009. Current
customers or customer who purchase prior to the software upgrade can upgrade
for free.
--------
Marc Ausman
http://www.verticalpower.com
RV-7 IO-390 Flying
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=226125#226125
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| Subject: | Re: 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 . . .
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