Today's Message Index:
----------------------
1. 01:16 AM - GT-50 G-meter (Martin & Chris)
2. 05:13 AM - Re: Feedline Radiation in Composite Airplane (h&jeuropa)
3. 06:50 AM - Static wicks (Jesse Jenks)
4. 07:31 AM - Re: Static wicks (Harley)
5. 08:38 AM - Wig Wag system (Jay Hyde)
6. 08:42 AM - Bridge Rectifier Terminal Identification (Jay Hyde)
7. 09:23 AM - Re: Static wicks (BobsV35B@aol.com)
8. 09:33 AM - Re: Bridge Rectifier Terminal Identification (Robert L. Nuckolls, III)
9. 09:48 AM - Re: Bridge Rectifier Terminal Identification (Sam Hoskins)
10. 10:10 AM - Re: Wig Wag system (marcausman)
11. 10:59 AM - Re: Feedline Radiation in Composite Airplane (Robert L. Nuckolls, III)
12. 08:24 PM - Re: Re: Wig Wag system (Ed Holyoke)
13. 09:52 PM - Re: Wig Wag system (marcausman)
14. 10:50 PM - Thoughts on the least evil antenna placements (rparigor@SUFFOLK.LIB.NY.US)
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Hi Peter,
I have fitted the GT-50 to both my aircraft ( one still under
construction) but I find it a very reasonably priced and accurate
instrument with a number of usefull functions. I wired it as per the
instructions, which means running the 'always on' wire direct to the
battery. Never had a problem with the Odyssey PC680 starting the RV-6,
but then again, I try and fly at least once a week. If you are worried
about battery drain, leave it disconnected till you need it or put a
switch in-line. Just means that the clock function will be only
accurate twice a day.....
Martin in Oz
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Subject: | Re: Feedline Radiation in Composite Airplane |
Had a similar problem with our Europa. Made a balun similar to the AeroElectric
you mentioned. Also tuned the antenna using a Antenna Analyzer.
Contact a local ham radio club to see if anyone has an Analyzer. The balun that
Bob describes, I found most references say that the the balun stub needs to
be an electrical quarter wave, so you have to shorten by the velocity factor of
the coax.
Balun will probably help a lot. I never could get ferrite beads to do much. I
also shielded some items with aluminum foil that is grounded to the aircraft
ground point and used shielded cable for wiring.
Jim Butcher
Europa XS N241BW
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=225637#225637
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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 i
s? I was always taught "they dissipate static electricity". Is static reall
y 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 though
t to control surface bonding=2C or static wicks.
Thanks.
_________________________________________________________________
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Subject: | Re: Static wicks |
They can work to dissipate static if they are attached to a conducting
surface. That way, 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, the plane is made of non conducting materials
(wood and fabric or fiberglass and/or epoxy), and a static wick will
only discharge the point that it is attached. A couple of inches away
from that point, 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), and then complain that they still
got zapped when they stepped off the truck. For those that really
thought they needed it, we would attach the wicks to the metal frame
under the truck. But, that often didn't help either, because the wick
was often dragging on a non conducting surface (epoxy sealed floors).
Also, 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,
because of the presence of the wire, but still built up on the hose
between the wire coil wraps.
In short, 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, 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.
>
> ------------------------------------------------------------------------
> Windows Live^(TM): Keep your life in sync. Check it out.
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These sound very interesting, but what is it suppoed to do???!! :-)
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Subject: | Bridge Rectifier Terminal Identification |
How do you figure out which terminals are which on one of these potted
bridge rectifiers? There are 3 tabs oriented the same way and one at 90 deg
to the others. my multimeter doesn't help either; I get 500 ohm between the
'ood' tab and two of the others when positively biased and infinite when
negatively biased..
Help?
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Message 7
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Subject: | Re: Static wicks |
Good Morning Jesse,
I have almost no experience in homebuilt aircraft, but I do have several
thousand hours in aircraft that were equipped with static wicks and several
thousand hours in aircraft with no static wicks applied.
My suggestion would be to thoroughly bond all control surfaces, flaps
included, 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 using the
HF transmitters and receiving on low frequency. I have encountered
precipitation static strong enough to knock out VHF communications for just a
very few
minutes, but that has never lasted more than four or five minutes.
I have also experienced static discharges, but that has always been on
aircraft that were equipped with static wicks. There is no doubt that I have flown
in much heavier precipitation in static wick equipped airplanes than I have
in airplanes that are not so equipped, but I have flown both in some rather
severe situations.
Wait and see if you have a problem.
If you lose VHF navigation capability in a heavy thunderstorm, you may want
to add static wicks or you may just decide to stay out of such conditions!
In any case, I have never seen a GPS signal affected by any static build up.
The only time I would suggest using static wicks is if your only means of
navigation is a LORAN. Even then, you don't need it if you stay out of
precipitation.
Summary? Bonding YES, Static Wicks? NO
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 1/19/2009 8:52:32 A.M. Central Standard Time,
jessejenks@hotmail.com writes:
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.
**************A Good Credit Score is 700 or Above. See yours in just 2 easy
steps!
cemailfooterNO62)
Message 8
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Subject: | Re: Bridge Rectifier Terminal Identification |
At 10:47 AM 1/19/2009, you wrote:
>How do you figure out which terminals are which
>on one of these potted bridge rectifiers? There
>are 3 tabs oriented the same way and one at 90
>deg to the others=85 my multimeter doesn=92t help
>either; I get 500 ohm between the =91ood=92 tab and
>two of the others when positively biased and infinite when negatively
biased..
>
>Help?
See:
http://aeroelectric.com/Pictures/Misc/s401-25.jpg
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 9
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Subject: | Re: Bridge Rectifier Terminal Identification |
B&C shows this: http://www.bandc.biz/Diode_Installation.pdf
On Mon, Jan 19, 2009 at 11:31 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:47 AM 1/19/2009, you wrote:
>
> How do you figure out which terminals are which on one of these potted
> bridge rectifiers? There are 3 tabs oriented the same way and one at 90
deg
> to the others=85 my multimeter doesn't help either; I get 500 ohm betwee
n the
> 'ood' tab and two of the others when positively biased and infinite when
> negatively biased..
>
> Help?
>
>
> See:
>
> http://aeroelectric.com/Pictures/Misc/s401-25.jpg
>
> Bob . . .
>
> ----------------------------------------)
> ( . . . a long habit of not thinking )
> ( a thing wrong, gives it a superficial )
> ( appearance of being right . . . )
> ( )
> ( -Thomas Paine 1776- )
> ----------------------------------------
>
>
> *
>
===========
===========
===========
===========
> *
>
>
Message 10
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Subject: | Re: Wig Wag system |
These flash the landing lights so that you can been more easily while in the air.
This is built into the Vertical Power system, or you can buy and wire a separate
"black box" to do this.
More advanced ones (like Vertical Power) will warm up the lights for a short period
of time before flashing, and/or turn off the pulsing automatically on the
ground and turn it on automatically in the air.
--------
Marc Ausman
http://www.verticalpower.com
RV-7 IO-390 Flying
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=225705#225705
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Subject: | Re: Feedline Radiation in Composite Airplane |
At 05:48 PM 1/18/2009, you wrote:
>
>I'm trying to help a builder kill the dragon in the subject line-
>
>Specifics: Garmin SL-30/40 with RG-400 to dipole on vertical stab
>spar immediately in front of rudder, terminated with ring
>connectors/screws/nuts. Coax terminated at radio using the supplied
>90 deg. Garmin/Apollo fitting and runs with other wiring through
>center floor tunnel to rear of plane, passing within about 12" from
>pitch servo. Dipole is two aluminum bars, 1/2"x1/16"x20" long for
>each element (I know this is a bit short- packaging issues. Optimum
>would be about 44" overall length, I believe)
>
>On com transmission, several systems are affected- Ray Allen trim
>LEDs dim, indicated EGT/CHT temps rise (EIS), and most excitingly,
>the autopilot (TruTrak) will occasionally re-direct the aircraft if
>engaged, usually in a pitch-up of variable amounts depending on
>frequency transmitting on. Usually worse at lower com freqs.
>
>My own research (Wikipedia has a pretty good article on dipole
>antennas(ae?) with several balun examples at end of article:
>http://en.wikipedia.org/wiki/Dipole_antenna ) indicates the coax is
>radiating lots of nasties off the shield, which I assume is making
>the mischief.
>
>Material from the Aeroelectric site (
>http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html )
>describes a balun for nav- is this same approach suitable for com?
>
>We've tried several ferrite ring arrangements, clamped around coax
>at various locations, rings near the antenna end etc. Most
>effective has been using a "ring", actually a small block that has
>two parallel holes through it- the center conductor at the antenna
>end is passed through one hole and back through the other in a tight
>"U" turn then connected to the element. I suspect this is helping
>simply by reducing the overall power output as it warms to the touch
>after a few transmissions by absorbing some of the RF energy in the conductor?
>
>A complicating factor may be that the rudder is attached by a
>contiuous stainless steel hinge pin that parallels the antenna
>full-length a bit over one inch away from it, but even with this pin
>removed, ground testing does not seem to indicate much of a change
>in the symptoms.
>Perhaps separating the upper and lower half of this pin and
>connecting the coax to them as the antenna elements might be a neat experiment?
>
>Also read
>http://www.aeroelectric.com/articles/Morris_Com_Loop_Antenna.pdf and
>curious if anyone can comment. This would fit into the tailcone
>nicely, but place the antenna loop within about 12-14" of the
>magnetometer and pitch servo.
>
>Any advice/insight/suggestions appreciated!
It's not likely that you're suffering from the effects of
feedline radiation.
Most avionics devices for the TC aircraft side of the
house have deep roots in designs optimized for metal
aircraft. A conductive airframe offers considerable
isolation between potential victims inside the airplane
from energies emitted by antennas outside the airplane.
With the advent of composite aircraft, our brothers
have found it prudent to qualify their products at
much higher levels of radiated susceptibility.
Virtually every instance in my experience for mitigating
a radiated susceptibility symptom involved combinations
of reduced radiation (move victim/antenna further apart)
or improving on the victim's ability to stand off the
more aggressive antagonist.
Ferrite beads over a coax are almost useless for
de-coupling the shield radiation of a poorly terminated
coax. I witnessed a demonstration in the lab wherein
a technician first terminated a 50 ohm coax with a
200 ohm load (4:1 swr). You could watch the swept
frequency SWR display and witness a small change in
presentation when you grabbed the coax with your hand.
This happens only if there are components of the
feedline energy flowing on the outside of the coax.
He added a half dozen donuts to the feedline right
at the end. There was no discernable benefit for
having added the beads. He then put all beads he
had on the coax . . . something over 20 pieces. You
you see SOME benefit but it was still not zero.
But in any case, the ratio of energy radiated
from a poorly matched coax versus radiated from
the physical antenna is huge. It's most likely
that you're suffering from the effects of sitting
inside sphere of strong radio frequence energy.
Adding a balun would not hurt anything.
http://www.aeroelectric.com/Reference_Docs/Antenna/BALUN_Analysis.pdf
http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html
Note that this balun does NOT use energy carried
inside the coax as part of the reactie network.
Thus you'll note that dimensions for the 1/4 wave
balun element and the antenna element are the same
length (open-air 1/4-wave).
Shorten the 26" dimensions to 23" for the comm
antenna. Then adjust ends of antenna elements for
lowest swr in center of range of interest (125 mhz).
Now, assuming this does not produce the hoped-for
result, you'll need to look at individual victims for
ways they can be made more tolerant of the environment
in which they're expected to perform.
Bob . . .
Message 12
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Subject: | Re: Wig Wag system |
I wig wag them on the ground to try and get the attention of all the
idiot drivers running around on the taxiways not looking out for
airplanes. I definitely don't want to turn 'em off automatically on the
ground.
Pax,
Ed Holyoke
marcausman wrote:
>
> These flash the landing lights so that you can been more easily while in the
air. This is built into the Vertical Power system, or you can buy and wire a separate
"black box" to do this.
>
> More advanced ones (like Vertical Power) will warm up the lights for a short
period of time before flashing, and/or turn off the pulsing automatically on the
ground and turn it on automatically in the air.
>
> --------
> Marc Ausman
> http://www.verticalpower.com
> RV-7 IO-390 Flying
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=225705#225705
>
>
>
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Subject: | Re: Wig Wag system |
Pat,
You can always turn off the feature so it will wig-wag all the time if that's what
you want. :) Nice thing is it is configurable using menus (to match each
builder's needs) rather than hard wired.
--------
Marc Ausman
http://www.verticalpower.com
RV-7 IO-390 Flying
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=225820#225820
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Subject: | Thoughts on the least evil antenna placements |
Wondering if I could get opinions on the least evil antenna placements
on my Europa XS Monowheel. Have a Bob Archer "E" style com
#1antenna in vertical fin for Becker com.
The question I
have is about placement of my Vertex handheld (panel mounted)nav com
antenna. It is an AAE that will be bent in half at 90 degrees so it should
work equal as bad on nav as it does on com (AAE said it should work about
70% of proper orientation for each)
I have a 121.5 / 246 ELT
antenna mounted on floor aft of D panel in baggage bay and will have AAE
transponder antenna mounted at least 20" away (aft) of AAE nav com
antenna for Becker 250 watt mode C transponder.
Now for opinion
needed, A or B:
A) Mount AAE nav com on starboard side which
place it 22" away from ELT antenna (same frequency) but allow the
RG400 antenna wire to go forward at 90 degrees for 22", then down at
a 45 degree angle for 1 foot, then a 45 degree andforward for a long
ways. Thus this routing puts antenna closer to ELT but has a friendlier
wire exit.
B) Place AAE nav com antenna 28" away from ELT
which is 6" further away from ELT compared to A, but exiting wire run
is not as friendly:
The RG 400 antenna wire can exit at 90 degrees
for 22", thengo down at a 45 degree angle for 1 foot, then
needs to make a 90 degree angle horizontal for 29" (this will be
parallel to the nav half of the antenna about 32" away), than make a
90 degree angle and go forward for a long ways.
OK what is the
least evil, A or B? Or any ideas welcome on a choice "C"
Thanking you in advance
Ron Parigoris
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