Today's Message Index:
----------------------
1. 03:12 AM - Thermocouple wire near ignition harness (Vic Yerevanian)
2. 05:38 AM - Re: ANL current limiters - Bob need you comment (Craig Mac Arthur)
3. 08:36 AM - Link (Bob C.)
4. 08:41 AM - ANL current limiters (Craig Mac Arthur)
5. 08:28 PM - Re: Antennas ()
6. 09:48 PM - Re: Where to install the hall effect sensor (Brian Lloyd)
7. 09:49 PM - Re: Thermocouple wire near ignition harness (Brian Lloyd)
8. 09:50 PM - Re: ANL current limiters - Bob need you comment (Brian Lloyd)
Message 1
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| Subject: | Thermocouple wire near ignition harness |
--> AeroElectric-List message posted by: "Vic Yerevanian" <vicster@netvigator.com>
Hello,
I am thinking of routing the thermocouple wires to the ungrounded EGT and
CHT probes along side the ignition harness. I do recall reading in a
previous message that the sensors have a low impedance and do not require
shielding. My installation manual doesn't caution against tying the TC wires
with the ignition harness, but I know of one manual that does. Can I firstly
tie the TC wires along side the ignition harness, and secondly does it need
to be shielded even though the probe is of the ungrounded type.
Thank you
Vic
Message 2
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| Subject: | Re: ANL current limiters - Bob need you comment |
--> AeroElectric-List message posted by: "Craig Mac Arthur" <jetfr8t@hotmail.com>
The ANL is a current limiter, not a noise limiter as the initials would make
you think. I'm not sure what ANL stands for. Probably a trade name. Anyhow,
their purpose is to protect the "B" lead against a large flow of current
from the battery if the alternator diodes get shorted to ground.
Craig
>From: jerb <ulflyer@verizon.net>
>To: aeroelectric-list@matronics.com
>Subject: Re: AeroElectric-List: ANL current limiters - Bob need you
>comment
>Date: Sat, 20 May 2006 21:31:08 -0500
>
>--> AeroElectric-List message posted by: jerb <ulflyer@verizon.net>
>
>I would think the ANL would go on the output lead/terminal of the
>alternator to reduce the noise component alternators generate. Time
>to see guidance form a higher level, Bob would you mind commenting on
>this topic.
>jerb
>
>At 04:56 PM 5/20/2006, you wrote:
> >--> AeroElectric-List message posted by: "Craig Mac Arthur"
> ><jetfr8t@hotmail.com>
> >
> >I understand that the ANL current limiter installed by the starter
>contactor
> >protects the "B" lead from a large current draw from the battery.
> >
> >My somewhat philosophical question is this: Why not use one to protect
>the
> >fat wire from the battery contactor to the main power distribution bus?
>Of
> >course, the battery contactor can be manually opened, but there is
> >recognition time and action required. Also, in the case of an accident
>that
> >damages where that wire penetrates the firewall, there is no automatic
> >protection for that wire.
> >
> >Craig Mac Arthur
> >
> >_________________________________________________________________
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> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
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Message 3
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--> AeroElectric-List message posted by: "Bob C. " <flyboy.bob@gmail.com>
I have a 10A CB that I want to feed off a buss bar (60A) it's only an
inch . . . what the proper way to do this . . . or is it a concern . .
. I't will be feeding a WigWag flasher on the other side of the CB so
it's not mission critical.
Regards,
Bob - SE Iowa (RV-8)
Message 4
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| Subject: | ANL current limiters |
--> AeroElectric-List message posted by: "Craig Mac Arthur" <jetfr8t@hotmail.com>
I found the answer to my own question. Bob answered it in another form a few
years ago. It's in a FAQ file, but it took me a couple of sessions to find
it. Here is the exchange:
Circuit protection for big wires
>I'm building an RV-8 with an aft mounted battery. I note that the
>electrical system schematics
in Bob's Appendix Z don't show any circuit protection on the big wires going
to the starter
contactor, and to the main fuse block. Both those wires will be quite long
in my installation,
and I'm concerned about the lack of protection. I have visions about a major
smoke in the
cockpit triggered by something chafing one of those cables, or a post crash
fire triggered by
arcing from the broken, but still live cables. I'm seriously considering
mounting the starter
contactor aft, beside the main contactor, next to the battery. That way the
cable going to the
starter will only be live during a start. That still leaves the long cable
going to the main fuse
block. Would it be practical to either make a large capacity fuselink, or
install a large CB or fuse
in that line? I would rather deal with an inflight short by seeing
everything go black, and then
selecting the essential bus alternate feed, than scrambling to throw the
battery master in the
middle of a major smoke in the cockpit event. Comments?
A The interesting thing about FAT wires in an airplane is that while they
carry the greatest
energy and potential for current flow, they represent the least hazard with
respect to electrical
faults. It's very difficult to create a hard fault on one of these wires.
Study the wire's pathway
through the airframe. What items of structure or loose systems might come to
bear on one of
these wires with sufficient force to compromise its insulation and produce a
hard short? If the
possiblity of such a scenario exists, it's easier to design out the
possibility than to provide
fusible protection for the wire.
If a fault does develop, it's most likely a "soft" fault that causes some
arcing (battery
wires rubbing the edge of a lightening hole is a good example) that simply
burns away the area
it touches without bringing down the system. Over 200,000 airplanes have
been built in this
country without fusible protection of the FAT wires. Like wing struts,
propeller shafts, flight
controls . . . it's relatively easy to product very low probability of
failure by design.
Another reader suggested that the battery contactor should be a hot-side
control as
opposed to cold-side control. A little study will show that it doesn't make
any difference which
side of the contactor is switched. A severe fault on the feedline downstream
of the contactor
will load the battery to a point perhaps low enough to cause the contactor
to open. When it
does, battery voltage comes back up and the contactor recloses. This sets up
a scenario for
"buzzing" of the battery contactor which almost always results in a welding
of the contactor.
It's really easy to protect he wire from faults to the degree that fuses
and/or breakers are not
necessary.
>>I have visions about a major smoke in the cockpit triggered by something
>>chafing one of
those cables, or a post crash fire triggered by arcing from the broken, but
still live cables.
A If it's an impending crash that you're preparing for, ALL SWITCHES OFF is
a good thing
to do before coming into contact with the earth.
>I'm seriously considering mounting the starter contactor aft, beside the
>main contactor, next to
the battery. That way the cable going to the starter will only be live
during a start.
A If you do this, you'll lose the advantage of tying alternator b-lead power
feeds to the
starter contactor and avoid bringing the noisiest wire in the airplane into
the cockpit for
attachment to the bus along with your audio system and radios. The power
distribution
diagrams in Appendix Z have evolved over more than 12 years of refining
ideas and
philosophies on owner built and maintained (OBAM) aircraft. I won't say that
they're infallible
nor would I suggest that we won't deduce good reasons for changes in the
future. Given the
rich database of history about fat wires in little airplanes and our
understanding of the
designed in failure modes of certified airplanes (see Chapter 17 of the
AeroElectric
Connection) I would counsel caution about major departures the philosophies
presently
illustrated by those drawings. Bob . . .
------
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Message 5
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--> AeroElectric-List message posted by: <gmcjetpilot@yahoo.com>
>From: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
>Aren't we talking about experimental aircraft ?
>By the way, why should aluminum RVs be able to
>hide antennas and not composite airplanes ?
>Wingtips, fin cap, etc...
>Regards, Gilles Thesee Grenoble, France
>http://contrails.free.fr
s'il vous plat
Yes Sir, there is no reason, but they work terribly,
that is a fact. The word, WORKS, to might mean
you can talk to the tower 5 miles in front of you,
but ATC 100-140 miles away no. I am totally put
off by wing tip antennas and like ideas (in metal
planes) because there is such a huge compromise
in radio performance. To me communications and
navigation is too important to safety to compromise
on so much for such a small gain in drag reduction.
> From: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
>Your HP values are way off, and I'll prove my point with
>analytical values and flight test data, beg your attention.
>
>Thank you for your message.
>I was quoting your numbers :
>***************************************
>"There is a recent article in Plane & Pilot which
>features the Socata Trinidad. Interesting enough,
>the engineers at Socata actually quantified the
>cruise speed impact of each antenna:"
>ADF - .75 knots
>G/S - .32 knots
>VOR - .59 knots
>ELT - .16 knots
>***************************************
>The total speed reduction is indeed in the vicinity of
>1.82 knot. We ought to include one COM antenna.
Fair enough but experimental's usually do not have
ADF's. Most split the VOR for the G/S so the speed
would be 0.75kts + COM, or about 1 kt (1.15 mph).
The values are MAX drag, but still it matches my
number with in 3% to 18%. Again the point is that
most people assume too much drag from the antennas
alone, so consider external antennas for max radio
performance for a little drag (metal planes. There is
lots of drag to get rid if, like cooling drag.
>Oh, you really should check
>http://contrails.free.fr/index_en.php
NICE!
>Just like weight reduction, small gains add to small
>gains, and in the end it makes quite a difference.
NO argument from me. Every little bit helps, however
the BIG PICTURE is on metal planes we just have
lousy, awful, terrible, severely restricted and limited
radio performance when we use wing top, empennage
cowl and cockpit antennas. They WORK but again
I want more than a 5 mile conversation with tower.
In the US we have large expanse of land and REMOTE
radio outlets. To get ATC for radar, Flight Watch for
weather or Flight Service to open / close flight plans,
a clear powerful radio is so so important. Also we
have many class B and C air spaces that require a
good radio.
This is what my hidden antenna friends heard all the time:
AIRCRAFT CALLING WASHINGTON CENTER YOU ARE
WEAK AND SCRATCHY, WHAT IS YOUR REQUEST?
SAY AGAIN?
It's not worth 1 mph, when you are going 195 mph.
>They are designed by, ahem, aircraft engineers. Many of
>them have the same "pas une affaire" background. The
>industry doesn't believe in the existence of drag. Especially
>in the land of cheap gas and big engines.
What land and engineers are we talking about, monsieur.
American engineers? pardonnez-moi
Land of cheap gas and big engines? America?
No offense taken, but give some examples to back up
your comment, aircraft engineers just know how to put a
big engines in from the "land of cheap gas and big engines".
I think a debate of airframes and engines are better for
another time or off this aeroelectric list.
I would say a long EZ, even with 160HP is way more efficient
than a MCR 4S or even a RV-9A with 115HP, and it has nothing
to do with engine size. I also say a RV-9A is more efficient than
your MCR 4S. Looking at the RV-9A with 115HP it has 10kt
faster speed (150kts). Not sure what engine you have 80 or
115 hp.
Anyway we can talk off line about efficency and
engine size. They are two different things.
>I just have to watch similar airplanes with their antennas
>sticking out, and receding in my slipstream ;-)
Ha ha ha ha good for you. Want to race my big engined
RV-7 with O360 190HP?
It would be a good experiment to take your buddies plane's
antennas off and do a before and after. You will than see what
it they really cost in speed.
As far as big engine's, I can dial my RV-7 back and fly
140 kts and burn about the same fuel as you do. However
I have the option to fly as fast as 192 kts. How do I say in
French, as I pass you?
au revoir, mangez ma poussire, voyez-vous plus
Cheers nice talking to you,
George
__________________________________________________
Message 6
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| Subject: | Re: Where to install the hall effect sensor |
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
On May 20, 2006, at 11:40 AM, Aart van't Veld wrote:
> --> AeroElectric-List message posted by: "Aart van't Veld"
> <avtveld@tiscali.nl>
>
> Guys,
>
> I have read all available info in the list on the Hall effect
> sensor to
> measure currents but would like some detailed input and pro's and
> cons on
> the different positions where to put these sensors, be it over battery
> cables, bus feeders or alternator b-leads. Your help is appreciated!
Well, there are three basic places you can put a current sensor
(shunt or hall-effect):
1. alternator B-lead (current source);
2. battery lead (current sink on charge or source on discharge);
3. bus feed (current sink).
If you want the whole picture you need at least two. If you know what
the alternator is producing and what the loads are consuming, the
difference is what is going into (or coming out of) the battery. If
you know what is going into the battery and coming out of the
alternator, the difference is what is being consumed in your loads.
If you have only one sensor you don't have enough information.
And of course this gets a bit more complex with multiple busses,
multiple alternators, and multiple batteries but the basic statements
above remain relevant.
But if I could have only one current sensor it would be in the B-lead
as an alternator load meter. By watching my load start higher and
then drop off, I know the battery is charging. I can also use it to
see what each load draws by turning loads on and off. It will also
tell you if you are working your alternator too hard.
But don't forget your voltmeter. That is more important than the
ammeter.
Brian Lloyd 361 Catterline Way
brian-yak AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
Message 7
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| Subject: | Re: Thermocouple wire near ignition harness |
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
On May 21, 2006, at 3:01 AM, Vic Yerevanian wrote:
> --> AeroElectric-List message posted by: "Vic Yerevanian"
> <vicster@netvigator.com>
>
> Hello,
>
> I am thinking of routing the thermocouple wires to the ungrounded
> EGT and
> CHT probes along side the ignition harness. I do recall reading in a
> previous message that the sensors have a low impedance and do not
> require
> shielding.
That is true.
> My installation manual doesn't caution against tying the TC wires
> with the ignition harness, but I know of one manual that does. Can
> I firstly
> tie the TC wires along side the ignition harness, and secondly does
> it need
> to be shielded even though the probe is of the ungrounded type.
If you are using an ungrounded type of thermocouple that is usually
because the instrument maker opted to save money on the device and
not use a differential input. Still, one side of the thermocouple
should be grounded in the instrument which will protect against any
high-voltages induced in the TC wiring.
And no, no shielding is necessary.
Brian Lloyd 361 Catterline Way
brian-yak AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
Message 8
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| Subject: | Re: ANL current limiters - Bob need you comment |
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
On May 21, 2006, at 5:29 AM, Craig Mac Arthur wrote:
> --> AeroElectric-List message posted by: "Craig Mac Arthur"
> <jetfr8t@hotmail.com>
>
>
> The ANL is a current limiter, not a noise limiter as the initials
> would make
> you think. I'm not sure what ANL stands for. Probably a trade name.
> Anyhow,
> their purpose is to protect the "B" lead against a large flow of
> current
> from the battery if the alternator diodes get shorted to ground.
It is just a kind of fuse.
Brian Lloyd 361 Catterline Way
brian-yak AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
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