Today's Message Index:
----------------------
1. 06:12 AM - Re: Sky-Tec starter (Robert L. Nuckolls, III)
2. 06:39 AM - Re: Load dump TVS (Jerzy Krasinski)
3. 07:00 AM - magnetic fields (Gary Casey)
4. 08:35 AM - Re: Source for Garmin GPS 400 antenna04 (royt.or@NetZero.com)
5. 09:22 AM - Re: magnetic fields (Robert L. Nuckolls, III)
6. 11:48 AM - Flap circuit relay questions ()
7. 12:25 PM - Re: Flap circuit relay questions (KITFOXZ@aol.com)
8. 02:33 PM - Re: Re: Flap circuit relay questions ()
9. 03:00 PM - Re: Flap circuit relay questions (Robert L. Nuckolls, III)
10. 03:56 PM - Re: Runaway stab trim prevention (bryan hooks)
11. 04:35 PM - Off line until Monday (Robert L. Nuckolls, III)
12. 05:46 PM - Garmin GPS Antenna (BAKEROCB@aol.com)
13. 07:31 PM - Re: Runaway stab trim prevention (Kenneth Melvin)
Message 1
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| Subject: | Re: Sky-Tec starter |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:01 AM 3/4/2004 -0600, you wrote:
>--> AeroElectric-List message posted by: "Troy Scott"
><tscott1217@bellsouth.net>
>
>Bob,
>
>Since I wrote that post in early January, I've made great progress in my
>electrical system understanding and planning, mostly due to what I've
>learned from your book and this forum. Also, the Sky-Tec company has
>graciously replaced my PM starter with their newer Inline starter, at a very
>reasonable price for the swap. The inrush current for this new-design
>starter promises to be about 100 amps less than the PM version.
That's another repeatable experiment I'd like to see undertaken.
A collection of contemporary starter offerings compared side-by-side
for speed-torque-current and inrush levels. It would sure clear
away a lot of potential for fog.
Bob . . .
Message 2
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| Subject: | Re: Load dump TVS |
--> AeroElectric-List message posted by: Jerzy Krasinski <krasinski@provalue.net>
Paul,
It seems to be24V device.
Jerzy
Paul Messinger wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>As I promised here is the device I mentioned a several weeks ago as being
>designed specifically for alternator load dump.
>
>LDP24A and the data sheet can be found by searching
>at www.st.com
>
>An interesting related app note AN554 is also at the st site. Provides
>detailed design info!
>
>www.findchips.com will find dist stock for the LDP24A
>
>
>Paul
>
>
>
>
Message 3
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--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
I started to wire the wings of my ES starting with a 14-gage ground braid
run out the trailing edge. It connects to all the hinges and to the
ailerons (carbon fiber). The power supply wires run out the leading edge.
Then I realized that the current to run the lights and pitot heat could
cause a magnetic field that might disturb the compass. That is, current
flowing out the leading edge and back at the trailing edge will create a
1-turn coil with about 4 feet between the two wires. Will this cause a
compass problem, requiring me to run another return wire in the leading
edge?
Gary Casey
Message 4
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| Subject: | Re: Source for Garmin GPS 400 antenna04 |
--> AeroElectric-List message posted by: royt.or@netzero.com
Gilles,
I'm using the noncertified (small, round, black) GPS antenna from http://www.gretzaero.com/ for my GPS295. The information on the web page implies this antenna should work with the GNS400 series. I've been happy with the service from Gretz Aero.
Regards,
Roy
N601RT: CH601HDS, nose gear, Rotax 912ULS, All electric, IFR equipped, 165hrs
Message 5
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| Subject: | Re: magnetic fields |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:58 AM 3/4/2004 -0800, you wrote:
>--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
>
>I started to wire the wings of my ES starting with a 14-gage ground braid
>run out the trailing edge. It connects to all the hinges and to the
>ailerons (carbon fiber). The power supply wires run out the leading edge.
>Then I realized that the current to run the lights and pitot heat could
>cause a magnetic field that might disturb the compass. That is, current
>flowing out the leading edge and back at the trailing edge will create a
>1-turn coil with about 4 feet between the two wires. Will this cause a
>compass problem, requiring me to run another return wire in the leading
>edge?
the ground wire for control surfaces and hinges should be
completely independent of those used for power distribution.
in a composite airplane it is useful to keep inbound and outbound
electron streams in close proximity to each other by means of
parallel wiring paths.
Bob . . .
Message 6
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| Subject: | Flap circuit relay questions |
--> AeroElectric-List message posted by: <chaskuss@bellsouth.net>
Bob & Listers,
I've been playing with AutoCAD (hey, this is fun!) to draw up my electrical system.
I know that Bob likes to install diodes on most relay coil circuits. I started
my flap motor circuit using the template from Bob's wire book. I believe
these are older versions of his current drawings. I note that the S704-1 relays
shown in this drawing do not have any diodes installed across the solenoid
coil wires.
Are these diodes of no value on this circuit?
If the diodes are of value, could I substitute an appropriate automotive (Bosch)
style relay with this diode built into the relay?
I see several drawings for this type of relay shown in Bob's Symbols file. I just
like the idea of using parts which can be purchased at the local auto parts
store. If the original fails in Yeehaw Junction, Florida (a real town) on Saturday
afternoon, I'd like to be able to purchase a replacement locally.
Charlie Kuss
RV-8A wiring
Boca Raton, Fl.
Message 7
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| Subject: | Re: Flap circuit relay questions |
--> AeroElectric-List message posted by: KITFOXZ@aol.com
Hello Charlie,
A diode across the relay's coil is always a good idea to prevent relay
"bounce" and to relieve contact wear on the controlling switch. I have not liked
the quality of the automotive relays that you are referring to. They are
usually rated for 30 amps but I have seen them weld their contacts with few cycles
and pure resistive loads of less than 20 amps. Why not use good quality relays
and if you must, cary a spare?
John P. Marzluf
Columbus, Ohio
Kitfox Outback (out back in the garage)
Message 8
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| Subject: | Re: Flap circuit relay questions |
--> AeroElectric-List message posted by: <chaskuss@bellsouth.net>
That's a good argument. However, automotive parts are of more than one quality.
I recently replaced the fuel pump relay on a 1991 BMW 525i with 226,000 miles.
The relay still worked. I simply replaced it when I changed the fuel pump as
a precaution. Genuine Bosch electrical parts are hard to beat, in my experience.
Stuff you buy at Pep Boys is worth every cent you pay for it (and not much
more)
Charlie
>
> From: KITFOXZ@aol.com
> Date: 2004/03/04 Thu PM 03:25:24 EST
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Flap circuit relay questions
>
>
Message 9
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| Subject: | Re: Flap circuit relay questions |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>
>A diode across the relay's coil is always a good idea to prevent relay
>"bounce"
the diode doesn't affect "bounce" . . . it does clamp off
the spike that emanates from every relay, contactor and solenoid
coil when the supply circuit is broken.
>and to relieve contact wear on the controlling switch.
. . . this the major benefit of the diode. See:
http://www.aeroelectric.com/articles/spikecatcher.pdf
> I have not liked
>the quality of the automotive relays that you are referring to. They are
>usually rated for 30 amps but I have seen them weld their contacts with
>few cycles
>and pure resistive loads of less than 20 amps.
I've been studying contact failure in switches and relays
at RAC now for several years. Just got a big pile of documents
from Honeywell to read on our way to the Groton seminar.
By and large, if a relay suffers the indignity of sticking or
welding, odds are that the designer didn't do his/her
homework when the relay was placed into service. Short
service life almost never has anything to do with characteristics
of the relay.
> Why not use good quality relays and if you must, cary a spare?
What is a "good quality" relay? Folks have been wrestling with
nebulous terms like "aircraft quality", "certified", "approved"
etc for decades without ever mentioning the numbers that define
how the product is expected to perform. Just because an
replacement relay comes in a metal can and costs more doesn't
guarantee squat about suitability to task or service life.
There was a time when I was skeptical of anything "plastic"
in the way of supposedly "robust" hardware. Nowadays, it's
difficult to find enclosed and/or semi-sealed relays that are
not plastic. Every thing under the hood of my '95 Safari,
the wife's '99 Saturn, and our '92 Ranger are plastic.
I had to replace one relay on a '90 Voyager's cooling fan
circuit . . . after I'd owned the car for 5 years and had
over 100K miles on it.
Single-pole, double-throw relays like B&C's S704
http://www.aeroelectric.com/Pictures/s704-1l.jpg
are manufactured by the millions by dozens of manufacturers
and every one of those folks finest hour is realized by getting
a contract from GM or Ford for relays. Unlike the high dollar
hardware we test the bejabbers out of and then bolt to perhaps
two dozen airplanes a year, the folks who supply these relays
have literally millions more opportunities per year to suffer
a relay failure. There is little difference in customer
perceptions of quality whether the relay cost $200 for
a biz jet or $20 for an automobile.
The short answer is that anything designed to operate
under the hood of a car is entirely suitable for use
on an airplane. The task on the airplane is a cake walk
by comparison.
I've been playing with AutoCAD (hey, this is fun!) to draw up my electrical
system. I know that Bob likes to install diodes on most relay coil
circuits. I started my flap motor circuit using the template from Bob's
wire book. I believe these are older versions of his current drawings. I
note that the S704-1 relays shown in this drawing do not have any diodes
installed across the solenoid coil wires.
Are these diodes of no value on this circuit?
It's not a barn burner if they're left off, sure doesn't hurt to install
them. Here's a picture of a suggested diode installation
on an S704 relay for the PM alternator disconnect circuit.
This would work in the flap system too. See:
http://www.aeroelectric.com/Pictures/s704inst.jpg
If the diodes are of value, could I substitute an appropriate automotive
(Bosch) style relay with this diode built into the relay?
Sure!
I see several drawings for this type of relay shown in Bob's Symbols file.
I just like the idea of using parts which can be purchased at the local
auto parts store. If the original fails in Yeehaw Junction, Florida (a real
town) on Saturday afternoon, I'd like to be able to purchase a replacement
locally.
That ought to work. I suspect you're going to experience
VERY long service life from these relays in a flap system.
Bob . . .
Message 10
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| Subject: | Runaway stab trim prevention |
--> AeroElectric-List message posted by: "bryan hooks" <hook3607@bellsouth.net>
Good point. Obviously didn't think that one through, but you're right.
Thanks,
bryan
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kevin
Horton
Subject: Re: AeroElectric-List: Runaway stab trim prevention
--> AeroElectric-List message posted by: Kevin Horton
<khorton01@rogers.com>
At 23:00 -0500 2/3/04, you wrote:
>--> AeroElectric-List message posted by: "bryan hooks"
><hook3607@bellsouth.net>
>
>Been off the list for a couple of bit.
>
>Sorry to have caused such an issue 'bout the runaway stab trim thing.
>Glad to hear that full trim at cruise is not that big a deal. I just
>posed the question for two reasons: (1) I don't have any RV experience
>yet and didn't know that it was really a non-event, and (2) the
airplane
>I fly at work can kill you (and actually has) if the trim runs away.and
>that's with a stab trim cut-out switch within reach of both pilots.
Now
>don't get me wrong, I never believed this would be a BIG problem in an
>RV, but I thought it could be an irritating event that might be
>prevented if there was something that could be done easily and cheaply
>to prevent it. Maybe I'll just remember where that ole trim circuit
>breaker is located.
>
>Bryan Hooks
>RV7A, slow
Well, runaway trim is quite different depending on whether the
aircraft has stab trim (i.e. the angle of incidence of the stab is
changed by the trim system) or an elevator trim tab. Stab trim
runaways can be very dangerous, as you can get in a situation where
you no longer have enough pitch authority in one direction. The
elevator may simply not be big enough to counter the pitching moment
created by the stab which has gone full travel.
If we have elevator trim tabs, like on your RV-7A, then we don't have
a problem of pitch authority. The only questions are how high the
stick force will be. But if you apply enough stick force you will
always be able to get enough pitch authority. In general, people who
have flight tested RVs to see the effect of trim runaways have
reported high, but manageable stick forces at high speed. The stick
forces lighten up as you slow down. Depending on how fast your trim
servo moves, it could get a bit exciting for a few seconds while you
figure out what is going on.
I've got a Matronics Speed Governor to slow my trim down, to give me
a bit more time to react. I've also got a button on my stick that
will kill power to the trim and wing leveler servos if I hold it
down. I can then reach over and turn off the trim power on the side
console.
So, if we are talking about RVs, don't talk about stab trim runaways,
as they don't exist, unless you have made a major design change.
--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
==
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Message 11
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| Subject: | Off line until Monday |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Dee and I are packing the car and getting ready to plow the
groove a little deeper up the turnpike to KC (we can save
about $400 on tickets by driving 3 hours to MCI).
The Groton CT seminar is Saturday and we're looking forward
to our second visit with these folks. See y'all Monday.
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
Message 12
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| Subject: | Garmin GPS Antenna |
--> AeroElectric-List message posted by: BAKEROCB@aol.com
AeroElectric-List message previously posted by: "GT"
<Gilles.Thesee@ac-grenoble.fr
<<Hi Bob and all, Do you have any advice as to what to choose for a Garmin
GPS 400 antenna ? The Garmin 400 series installation manual calls for a Garmin
GA 56 GPS antenna or an antenna meeting particular requirements. The antennas
meeting those requirement are usually big white streamlined things. As our
intention is to mount the antenna on the glareshield, I would like to find a less
bulky and breferably dark coloured model. I have already seen such models
with other Garmin GPS. Do you know if such an antenna could work with the 400
model ? Thanks in advance,
Regards, Gilles >>
4/4/2004
Hello Gilles, If appearance is your primary concern why not mount the antenna
on a small aluminum shelf suspended underneath either the glare shield or a
bit further forward under the cowling? I assume that neither the glare shield
or cowling are made of metal.
The antenna for my Garmin 430 is out of sight on such a shelf aft of the
firewall and forward of the glareshield. It works great.
One additional benefit of having the antenna mounted on an aluminum shelf is
that the aluminum partially shields the bottom of the antenna from electronic
garbage happening below the shelf.
'OC' Baker, Builder of KIS TR-1 #116 4/14/97 - 11/17/03
Message 13
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| Subject: | Runaway stab trim prevention |
--> AeroElectric-List message posted by: Kenneth Melvin <melvinke@direcway.com>
I have had a runaway elevator trim in an RV4 while inverted at close to
200mph. The stick-mounted switch in the front cockpit had shorted out
when the stickgrip broke. It was a devastating control issue, and by the
time one recognized what was going on, and using two hands to try to
overcome the stick force, no switch or breaker was going to help.
Slowing to approach speed made control manageable, but landing would
have required considerable finesse. Fortunately I had installed another
trim switch in the rear cockpit, which allowed the passenger to correct
the problem.
Kenneth Melvin, N36KM
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of bryan
hooks
Subject: RE: AeroElectric-List: Runaway stab trim prevention
--> AeroElectric-List message posted by: "bryan hooks"
<hook3607@bellsouth.net>
Good point. Obviously didn't think that one through, but you're right.
Thanks,
bryan
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kevin
Horton
Subject: Re: AeroElectric-List: Runaway stab trim prevention
--> AeroElectric-List message posted by: Kevin Horton
<khorton01@rogers.com>
At 23:00 -0500 2/3/04, you wrote:
>--> AeroElectric-List message posted by: "bryan hooks"
><hook3607@bellsouth.net>
>
>Been off the list for a couple of bit.
>
>Sorry to have caused such an issue 'bout the runaway stab trim thing.
>Glad to hear that full trim at cruise is not that big a deal. I just
>posed the question for two reasons: (1) I don't have any RV experience
>yet and didn't know that it was really a non-event, and (2) the
airplane
>I fly at work can kill you (and actually has) if the trim runs away.and
>that's with a stab trim cut-out switch within reach of both pilots.
Now
>don't get me wrong, I never believed this would be a BIG problem in an
>RV, but I thought it could be an irritating event that might be
>prevented if there was something that could be done easily and cheaply
>to prevent it. Maybe I'll just remember where that ole trim circuit
>breaker is located.
>
>Bryan Hooks
>RV7A, slow
Well, runaway trim is quite different depending on whether the
aircraft has stab trim (i.e. the angle of incidence of the stab is
changed by the trim system) or an elevator trim tab. Stab trim
runaways can be very dangerous, as you can get in a situation where
you no longer have enough pitch authority in one direction. The
elevator may simply not be big enough to counter the pitching moment
created by the stab which has gone full travel.
If we have elevator trim tabs, like on your RV-7A, then we don't have
a problem of pitch authority. The only questions are how high the
stick force will be. But if you apply enough stick force you will
always be able to get enough pitch authority. In general, people who
have flight tested RVs to see the effect of trim runaways have
reported high, but manageable stick forces at high speed. The stick
forces lighten up as you slow down. Depending on how fast your trim
servo moves, it could get a bit exciting for a few seconds while you
figure out what is going on.
I've got a Matronics Speed Governor to slow my trim down, to give me
a bit more time to react. I've also got a button on my stick that
will kill power to the trim and wing leveler servos if I hold it
down. I can then reach over and turn off the trim power on the side
console.
So, if we are talking about RVs, don't talk about stab trim runaways,
as they don't exist, unless you have made a major design change.
--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
==
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