Today's Message Index:
----------------------
1. 06:44 AM - Garmin 296 Antenna Cable (BobsV35B@aol.com)
2. 07:25 AM - Size of Fuse vs. Circuit Breaker (Dennis Johnson)
3. 08:00 AM - Re: Size of Fuse vs. Circuit Breaker (Matt Prather)
4. 08:35 AM - Re:GRT Magnetometer reliance (dedgemon@knology.net)
5. 08:51 AM - Re: Garmin 296 Antenna Cable (Phil Birkelbach)
6. 01:34 PM - Re: Size of Fuse vs. Circuit Breaker (Robert L. Nuckolls, III)
7. 02:44 PM - Re: shielded wires (Robert L. Nuckolls, III)
8. 03:03 PM - Size of Fuse vs. Circuit Breaker - Corrected (Robert L. Nuckolls, III)
9. 08:59 PM - Big H-bridge for Big Motors (Robert L. Nuckolls, III)
10. 09:22 PM - Re: Big H-bridge for Big Motors (Robert L. Nuckolls, III)
Message 1
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| Subject: | Garmin 296 Antenna Cable |
--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 2/10/2005 8:22:19 A.M. Central Standard Time,
jcorner@shaw.ca writes:
Bob
I replaced the antenna cable plug on my 295 and didn't have any problems.
Can't see why the 296 should be any different
Jim
Good Morning Jim,
I agree totally, I just thought that it would be nicer if the plug did not
have to be cut off each time it was desired to remove the portable unit from
the airplane.
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Airpark LL22
Downers Grove, IL 60516
630 985-8502
Message 2
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| Subject: | Size of Fuse vs. Circuit Breaker |
--> AeroElectric-List message posted by: "Dennis Johnson" <pinetownd@volcano.net>
Greetings,
I'm finally getting to the point of beginning the detailed electrical design stage
of my Lancair Legacy. Although I'm planning to use fuses, I noticed in AC
43.13-1B, Table 11-3, that for certain wire sizes, it calls for a substantially
larger circuit breaker rating than for a fuse. For example, a 14 AWG wire
can be protected by a 20 amp breaker or a 15 amp fuse.
Since I'm going to be using nearly all fuses, it doesn't particularly matter to
my design, but just for educational purposes, I'm curious. I thought that fuses
generally acted faster in response to mild overloads than breakers, but AC
43.13 seems to say the opposite. What gives?
Thanks,
Dennis Johnson
Legacy #257
Message 3
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| Subject: | Re: Size of Fuse vs. Circuit Breaker |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
Hi Dennis,
I can think of two reasons for what you noticed. Both are pure speculation.
The first thing I noticed when looking at the chart was that the fuses
were to
be of MILF15160 or equivalent. I Google'ed that and found
lots of references
to it, many mentioning that it had been abandoned. None that I saw (not an
exhaustive search) described the technical characteristics of the standard.
I wonder if this MIL spec is for a fuse that has relatively slow blow
characteristics.
The other thing that I noticed about the chart is that the values for the
fuses
are sometimes equal to the CB value and sometimes less. My other speculation
is that they picked commonly available CB ratings, and that in some cases an
equivalent fuse rating didn't exist. At the time of the AC writing were
there any
7.5A fuses? The only safe choice would be to use the next smaller size fuse.
Again, pure speculation on my part. Anyone find this MIL spec?
A link to the AC43-13 Chapter 11.
http://www.faa.gov/certification/aircraft/av-info/dst/43-13/Ch_11-04.doc
Regards,
Matt-
> --> AeroElectric-List message posted by: "Dennis Johnson"
> <pinetownd@volcano.net>
>
> Greetings,
>
> I'm finally getting to the point of beginning the detailed electrical
> design stage of my Lancair Legacy. Although I'm planning to use fuses,
> I noticed in AC 43.13-1B, Table 11-3, that for certain wire sizes, it
> calls for a substantially larger circuit breaker rating than for a fuse.
> For example, a 14 AWG wire can be protected by a 20 amp breaker or a 15
> amp fuse.
>
> Since I'm going to be using nearly all fuses, it doesn't particularly
> matter to my design, but just for educational purposes, I'm curious. I
> thought that fuses generally acted faster in response to mild overloads
> than breakers, but AC 43.13 seems to say the opposite. What gives?
>
> Thanks,
> Dennis Johnson
> Legacy #257
>
>
Message 4
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| Subject: | RE:GRT Magnetometer reliance |
--> AeroElectric-List message posted by: "dedgemon@knology.net" <dedgemon@knology.net>
Mike, et.al.
I think that one of the common misconceptions about AHARS units is that
are an all digital "analog" of a vacuum gyro system, but if fact they
operate very differently.
The AHARS units are actually full blown IMU units like we use in missiles,
subs, etc... We just don't really care about where we are, just our
attitude angles. The basic way that you do this is to use 3 rate gyros and
3 accelerometers and integrate the signals. This allows us to propogate
our position and attitude from a "KNOWN" position and attitude. Note that
we are just integrating this original data forward, we can't "measure" our
attitude with just rate gyros and accels. For that we need something else
to reference to. In the missile world we often use GPS data to perform
GPS aiding, this works really well, (as long as GPS is up). Note that we
also use sensors that are much, much better than whats in the AHARS units
that we're all flying (they cost a ton too).
So what to do. Everyone that I'm familiar with (Dynon, Blue mountain, GRT,
etc...) is using a 3 axis magnetometer (not just a compass, but 3 axis) to
provide a nice low frequency stable signal for the Kalman filter. This can
work very well and doesn't depend on outside signals. If the magnetometer
craps out completely the AHARS solution will start to drift and slowly
gets poor (how slow depends on the quality of the sensors). This is much
like a vacuum gyro spinning down. But what if the magnetometer starts
putting out bad data. If that can be sensed then we're probably better off
just shutting the thing down.
Hope this helps.
---
David Edgemon
Summit Research Corp.
256-876-4884
"On the side of the box it said to install Windows 95 or
better, so I installed Linux" Anonymous
________________________________ Message 5
_____________________________________
Time: 04:20:37 AM PST US
Subject: AeroElectric-List: GRT Magnetometer reliance
From: "Stewart, Michael (ISS Atlanta)" <mstewart@iss.net>
--> AeroElectric-List message posted by: "Stewart, Michael (ISS Atlanta)"
<mstewart@iss.net>
Hey guys,
I learned something yesterday that is very important to know.
I uploaded the recent software into the GRT EFIS. The upload procedure
was... frankly... amazing.
Insert usb chip into unit, turn knob, and watch. How cool is that? I
walked over to my buddy's house who has the dual units installed and
updated his. He thought I was very cool. I told him... Its not me, its
GRT. A monkey could do it. A very dumb monkey could do it.
Anyway, after the upload my attitude did not work and an e-mail to Todd
at GRT resulted in the answer. The new version does not show an attitude
if the magnetometer is not connected, or fails. The reason being that it
needs that data to complete the AHARS solution for attitude. I am still
going back and forth with Todd to determine if there is a better way for
them to handle an in flight manometer failure than just going TU, but
for now this is the behavior you will see in flight.
Since the attitude reading requires compass data, I have asked them to
look at some other solution like an "ahars unreliable" flag, or
countdown to going TU, or something other than instant TU. I do not know
what testing led to this new software change but I have to figure that
there is some period of time after loss of compass data that it is
usable, or partially usable.
Also since it is getting ground track from a gps source over a serial
data stream, could this not be used as a backup piece of data while the
compass is out? I dunno. But I do know "Other" competitors do not rely
on external devices to complete the solution for attitude.
Thoughts group?
Mike Stewart
Basement flying the GRT.
S8 FWF
Message 5
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| Subject: | Re: Garmin 296 Antenna Cable |
--> AeroElectric-List message posted by: Phil Birkelbach <phil@petrasoft.net>
I have no intention of ever removing the antenna from the plane. I will
remove the GPS but the antenna is permanent, if I need another antenna
I'll just buy one.
I appreciate everyone's comments. I'll probably cut that thing off this
weekend and see if it works. I'll try to remember to report my results.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB - Panel
http://www.myrv7.com
BobsV35B@aol.com wrote:
>--> AeroElectric-List message posted by: BobsV35B@aol.com
>
>
>In a message dated 2/10/2005 8:22:19 A.M. Central Standard Time,
>jcorner@shaw.ca writes:
>
>Bob
>
>I replaced the antenna cable plug on my 295 and didn't have any problems.
>Can't see why the 296 should be any different
>
>Jim
>
>
>Good Morning Jim,
>
>I agree totally, I just thought that it would be nicer if the plug did not
>have to be cut off each time it was desired to remove the portable unit from
>the airplane.
>
>Happy Skies,
>
>Old Bob
>AKA
>Bob Siegfried
>Ancient Aviator
>Stearman N3977A
>Brookeridge Airpark LL22
>Downers Grove, IL 60516
>630 985-8502
>
>
>
>
Message 6
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| Subject: | Re: Size of Fuse vs. Circuit Breaker |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 07:23 AM 2/10/2005 -0800, you wrote:
>--> AeroElectric-List message posted by: "Dennis Johnson"
><pinetownd@volcano.net>
>
>Greetings,
>
>I'm finally getting to the point of beginning the detailed electrical
>design stage of my Lancair Legacy. Although I'm planning to use fuses, I
>noticed in AC 43.13-1B, Table 11-3, that for certain wire sizes, it calls
>for a substantially larger circuit breaker rating than for a fuse. For
>example, a 14 AWG wire can be protected by a 20 amp breaker or a 15 amp fuse.
>
>Since I'm going to be using nearly all fuses, it doesn't particularly
>matter to my design, but just for educational purposes, I'm curious. I
>thought that fuses generally acted faster in response to mild overloads
>than breakers, but AC 43.13 seems to say the opposite. What gives?
In a nutshell . . . selection of a wire size is driven by two
considerations: (1) temperature rise as it affects the insulation
on the wire and (2) voltage drop to be tolerated over the length
of the wire run. The copper in a 22AWG wire will very happily
carry 15 amps at room temperature and free air. I just hooked a
16" piece of 22759/16 to a power supply and jacked it up to 15
amps. 20 minutes later, the wire was way too hot to touch. Voltage
drop was about 0.7 volts. No smells. No smoke. If this had been
PVC wire instead of Tefzel, perhaps the PVC would have melted off
the wire . . . no sweat, go with Teflon.
The REAL answers to your questions are:
(1) how will the wire to be protected be loaded?
to 200 amps or more to crank an engine. Is this
a bad deal? AC43-13 sez protect this wire at
100A breakers or 70A with fuses. Section 5 of
Chapter 11 goes into lots of explanation for
rating wires and takes voltage drop and temperature
rise into consideration. Table 11-9 speaks to
continuous current ratings for wire but consider
notes at the bottom of the table where one reads
that the numbers apply for 70C ambients and free
air . . . higher ambient temps and burying a wire
inside a bundle gives one reasons to derate a wire
still further. One can tolerate what might be
considered severe overloading for short times as
long as voltage drop can be tolerated.
I recommend 4AWG fat wiring for aircraft where
battery is very close to engine. When battery
and engine are on opposite ends of airplane, 2AWG
is recommended. In some seaplanes, 0AWG is
called for. This decision is driven by voltage
drop issues during cranking.
(2) what is the temperature rating of the insulation on
the wire?
issues, then insulation sets the current limits
105C, Tefzel limits at 150C, Teflon goes to 200C.
Got some asbestos sleeving laying around? Slip
that stuff over your wire and you can run it
up to cherry red temperatures. Is the wire hanging
out in the breeze for cooling or is it wrapped up
in a bundle with lots of other wires that
contribute their own heat dissipations to the
equation. Note that we STILL haven't talked about
fuses or circuit breakers.
(3) what kind of load does the wire feed?
be considered? Fuses tend to be faster than thermal
breakers. Magnetic breakers are faster than most
fuses. Virtually ANY form of circuit protection can
be sized to adequately protect ANY wire. You won't
find a considered one-size-fits-all from the charts
and tables. A good case in point deals with pitot
tube heaters. Cold resistance is very high and
warmup speeds relatively slow. Some builders have
resorted to 30A fuses to protect a 14AWG wire driving
a 100W heated pitot that runs under 10 amps after
it warms up.
The charts and tables will be conservative suggestions
that cover most situations but understand that some
systems will present special issues that drive
CONSIDERED departure from suggestions. There's no
substitute for knowing how the system works and
selecting both wire and circuit protection based
on that understanding.
Bob . . .
Message 7
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| Subject: | RE: shielded wires |
0$60085fd8@scottcomp>
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:52 AM 2/9/2005 -0500, you wrote:
>Hi Bob , thanx for getting back to me. I have a Stratomaster Ultra which has
>a very poor wiring diagram and a flightcom 11gx intercom that on my previous
>plane I tried to wire to ship power and had to go back to it's internal
>battery due to ignition noise .I want to hard wire a hand held GPS and COM
>as well as the intercom to ships power on my sonex and don't want the noise.
>I got all the sheilded wire for free from work. Im not real clear on what
>wires I should sheild so as I have the wire I thought , everything! This is
>no dought over kill but I dont want noise . The engine I'm using has 2 mags
>and electronic ignition it's the aero vee from sonex. I had planned on using
>ACS keyed ignition switch for the mags and a toggle switch for the
>electronic ignition. Any help you can give would be really great as this
>set up is very close to my last plane , and it had noise! Scott Cameron .
>sonex164@netscape.ca
Okay. First, it's unlikely that shielding ANY wires will offer
a significant degree of noise reduction. 95% plus of all noise
problems are either conducted noise, ground loop noise, or RF
radiated noise. I can't recall the last time I fixed a problem
by shielding wire(s).
What KIND of noise were you hearing? Ignition? Alternator?
Some other antagonist. Given the simplicity of this airplane,
lets just wire-er-up and see what happens. If you do have a noise
problem, we need to deduce antagonist and propagation mode.
It's most likely that your problems were either conducted in
on the 14vdc power (needs a filter) or radiated into the antenna
(here you may be hosed . . . some folks have had a difficult
time getting some ignition systems to shut up).
Bob . . .
Message 8
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| Subject: | Size of Fuse vs. Circuit Breaker - Corrected |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 07:23 AM 2/10/2005 -0800, you wrote:
>--> AeroElectric-List message posted by: "Dennis Johnson"
><pinetownd@volcano.net>
>
>Greetings,
>
>I'm finally getting to the point of beginning the detailed electrical
>design stage of my Lancair Legacy. Although I'm planning to use fuses, I
>noticed in AC 43.13-1B, Table 11-3, that for certain wire sizes, it calls
>for a substantially larger circuit breaker rating than for a fuse. For
>example, a 14 AWG wire can be protected by a 20 amp breaker or a 15 amp fuse.
>
>Since I'm going to be using nearly all fuses, it doesn't particularly
>matter to my design, but just for educational purposes, I'm curious. I
>thought that fuses generally acted faster in response to mild overloads
>than breakers, but AC 43.13 seems to say the opposite. What gives?
In a nutshell . . . selection of a wire size is driven by two
considerations: (1) temperature rise as it affects the insulation
on the wire and (2) voltage drop to be tolerated over the length
of the wire run. The copper in a 22AWG wire will very happily
carry 15 amps at room temperature and free air. I just hooked a
16" piece of 22759/16 to a power supply and jacked it up to 15
amps. 20 minutes later, the wire was way too hot to touch. Voltage
drop was about 0.7 volts. No smells. No smoke. If this had been
PVC wire instead of Tefzel, perhaps the PVC would have melted off
the wire . . . no sweat, go with Teflon.
The REAL answers to your questions are:
(1) how will the wire to be protected be loaded?
Discussion: We routinely load 4AWG FAT wires in our airplanes
to 200 amps or more to crank an engine. Is this
a bad deal? AC43-13 sez protect this wire at
100A breakers or 70A with fuses. Section 5 of
Chapter 11 goes into lots of explanation for
rating wires and takes voltage drop and temperature
rise into consideration. Table 11-9 speaks to
continuous current ratings for wire but consider
notes at the bottom of the table where one reads
that the numbers apply for 70C ambients and free
air . . . higher ambient temps and burying a wire
inside a bundle gives one reasons to derate a wire
still further. One can tolerate what might be
considered severe overloading for short times as
long as voltage drop can be tolerated.
I recommend 4AWG fat wiring for aircraft where
battery is very close to engine. When battery
and engine are on opposite ends of airplane, 2AWG
is recommended. In some seaplanes, 0AWG is
called for. This decision is driven by voltage
drop issues during cranking.
(2) what is the temperature rating of the insulation on
the wire?
Discussion: As long as you're not dealing with voltage drop
issues, then insulation sets the current limits
105C, Tefzel limits at 150C, Teflon goes to 200C.
Got some asbestos sleeving laying around? Slip
that stuff over your wire and you can run it
up to cherry red temperatures. Is the wire hanging
out in the breeze for cooling or is it wrapped up
in a bundle with lots of other wires that
contribute their own heat dissipations to the
equation. Note that we STILL haven't talked about
fuses or circuit breakers.
(3) what kind of load does the wire feed?
Discussion: Are there large inrush or high momentary loads to
be considered? Fuses tend to be faster than thermal
breakers. Magnetic breakers are faster than most
fuses. Virtually ANY form of circuit protection can
be sized to adequately protect ANY wire. You won't
find a considered one-size-fits-all from the charts
and tables. A good case in point deals with pitot
tube heaters. Cold resistance is very high and
warmup speeds relatively slow. Some builders have
resorted to 30A fuses to protect a 14AWG wire driving
a 100W heated pitot that runs under 10 amps after
it warms up.
The charts and tables will be conservative suggestions
that cover most situations but understand that some
systems will present special issues that drive
CONSIDERED departure from suggestions. There's no
substitute for knowing how the system works and
selecting both wire and circuit protection based
on that understanding.
Bob . . .
Message 9
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| Subject: | Big H-bridge for Big Motors |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Here's a sketch of an h-bridge configuration I've used many
times for big motors. The parts shown will easily handle motors
up to and including 10A if the transistors (especially the
p-channel) are heat-sinked.
Bob . . .
--------------------------------------------------------
< Throughout history, poverty is the normal condition >
< of man. Advances which permit this norm to be >
< exceeded -- here and there, now and then -- are the >
< work of an extremely small minority, frequently >
< despised, often condemned, and almost always opposed >
< by all right-thinking people. Whenever this tiny >
< minority is kept from creating, or (as sometimes >
< happens) is driven out of a society, the people >
< then slip back into abject poverty. >
< >
< This is known as "bad luck". >
< -Lazarus Long- >
<------------------------------------------------------>
http://www.aeroelectric.com
Message 10
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| Subject: | Re: Big H-bridge for Big Motors |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Guess it would help if I put the link in too . . .
http://www.aeroelectric.com/Pictures/Big_H-Bridge.gif
At 10:58 PM 2/10/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
><b.nuckolls@cox.net>
>
>Here's a sketch of an h-bridge configuration I've used many
>times for big motors. The parts shown will easily handle motors
>up to and including 10A if the transistors (especially the
>p-channel) are heat-sinked.
>
>
> Bob . . .
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