Today's Message Index:
----------------------
1. 04:35 AM - Re: Re: High Current Switch or Battery Contactor (Brian Lloyd)
2. 04:58 AM - Re: O2 sensor for Rotax 914? (Ken)
3. 05:01 AM - Electrical system ergonomics (was: EXP BUS 2V idea - what do you think?) (Brian Lloyd)
4. 05:03 AM - Re: Re: High Current Switch or Battery Contactor (Brian Lloyd)
5. 07:22 AM - Re: Electrical system ergonomics (James E. Clark)
6. 08:35 AM - Re: Electrical system ergonomics (Brian Lloyd)
7. 05:38 PM - Re: Electrical system ergonomics (Brian Sowell Home)
8. 10:54 PM - Re: Electrical system ergonomics (James E. Clark)
9. 10:58 PM - Re: Electrical system ergonomics (James E. Clark)
Message 1
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| Subject: | Re: High Current Switch or Battery Contactor |
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
On Dec 8, 2004, at 9:17 AM, Gary Casey wrote:
> I've been thinking about the same thing and there is one failure mode
> that
> bothers me: Let's say that in flight you need to shut off the master
> bus,
> so you turn off the manual switch. Oops, the alternator and voltage
> regulator are connected "downstream" of the master switch and hence
> keep
> right on working, keeping the master bus live.
Hmm, I just don't see how that would happen. The battery master switch
is a double-pole, single-throw switch. One pole activates the battery
master contactor and the other pole provides power to the alternator
controller/field circuit. When you turn off the battery master you
automatically turn off the alternator field circuit. No split-master
required. If you want to deactivate the alternator while leaving the
battery on, you just pull the alternator field breaker. The alternator
field was the only circuit breaker I had in my RV-4. Everything else
was on fuse blocks, one for the main buss and one for the e-buss.
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
+1.340.998.9447 St. Thomas, VI 00802
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
Message 2
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| Subject: | Re: O2 sensor for Rotax 914? |
clamav-milter version 0.80j
on juliet.albedo.net
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
There have been links posted for both wide and narrow band O2 sensors.
Hopefully it is common knowledge that any display connected to a narrow
band sensor can only tell rich or lean of stoich (14.7). A narrow band
sensor is really more of a stoich switch than anything. It generates a
voltage that goes off and on depending on whether the mixture is rich or
lean of stoich. If it is alternating on and off we assume a stoich
mixture. Which is all fine if that is sufficient for your needs. However
there are several sold with displays (typically in the $100. range) that
pretend to give more information. I wouldn't put a lot of meaning in
them other than rich or lean of stoich. IMO a one light bulb display
gives the same amount of information (On-off-flashing) but it would
require a bit more effort to interpret.
O2 sensors first appeared as a way of controlling the mixture at stoich
so that enough unburned hydrocarbons would get to the catalytic
converter to keep it lit during cruise and idle. (OK in poorly setup
engines that cruised way too rich, it did occasionally help mileage).
Engine computers assume a fault if the sensor stops switching and stays
on or off too long.
Kits for wide band sensing systems have become available for a couple of
hundred dollars. Somewhat sophisticated control electronics is required
to run the sensor, and the sensors are pricier, but they may be a better
value depending on what you want to do. I think that it is safe to say
that it is a narrow band sensor unless it has at least 5 wires.
Ken
923te wrote:
>--> AeroElectric-List message posted by: "923te" <923te@cox.net>
>
>Hi Brian,
>
>Thanks for reminding me of the Westach. here is a link to their
instrument.
>Is this similar to what you had?
>
>
Message 3
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| Subject: | Electrical system ergonomics (was: EXP BUS 2V idea |
- what do you think?)
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
As someone who is working on the ergonomics of several different
systems (not just aircraft) right now, I find the tendency toward
complexity interesting. The first rule is to make normal operation as
simple and obvious as possible. (I eschew the word 'intuitive' here as
there is nothing intuitive about an airplane cockpit unless you are
already a pilot.) Could your pilot buddy who has never flown your
airplane before climb in and have a snowball's chance of making your
electrical system work? If not, go back to the drawing board.
Think about it. Why would you need external switches for things that
have their own switches already? Joe 6-pack pilot knows that if he/she
wants to turn off a radio he/she reaches up to the radio and turns off
its power switch. No need to hunt around the cockpit for YAFS (yet
another switch) and no additional point of failure.
We spend so much time thinking about all the clever ways we want to
have to deal with failure that we forget that it just doesn't happen
often enough to try to streamline the process. Heck, think about your
engine-out or aircraft fire litany. It just isn't all that simple and
it involves much pushing, pulling, and switching but you manage anyway.
Why should electrical system failure be any different. Here:
Electrical system failure emergency checklist:
1. turn on e-buss switch;
2. turn off battery master switch;
3. turn off all unnecessary loads (usually extra radios) on the e-buss;
4. fly to a place where a landing may be effected most safely for
troubleshooting.
It just isn't all that difficult to do even in the heat of dealing with
an emergency.
And one other thing about alternator failure. They don't fail all that
often but when they do our tendency is to think that the failure is
electrical in nature rather than mechanical. I had an alternator
failure once that involved one of the bearings. The only symptom I had
was that the alternator just dropped off-line. You see, the armature
has started to wander around inside the case and had started to chew up
the stator but there was no hint of that in the cockpit. If I had
continued instead of landing the damage might have been much worse.
Imagine the case of the alternator shattering and the armature merrily
wandering around the engine compartment visiting all its friends in
there.
So even if you have all the continue-on capability you can design into
your system, any sort of failure that could be construed as possibly
being mechanical is grounds to get on the ground. The life you save me
be that of your wallet.
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
+1.340.998.9447 St. Thomas, VI 00802
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
Message 4
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| Subject: | Re: High Current Switch or Battery Contactor |
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
On Dec 9, 2004, at 8:34 AM, Brian Lloyd wrote:
> --> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
>
> On Dec 8, 2004, at 9:17 AM, Gary Casey wrote:
>
>> I've been thinking about the same thing and there is one failure mode
>> that
>> bothers me: Let's say that in flight you need to shut off the master
>> bus,
>> so you turn off the manual switch. Oops, the alternator and voltage
>> regulator are connected "downstream" of the master switch and hence
>> keep
>> right on working, keeping the master bus live.
>
> Hmm, I just don't see how that would happen. The battery master switch
> is a double-pole, single-throw switch. One pole activates the battery
> master contactor and the other pole provides power to the alternator
> controller/field circuit. When you turn off the battery master you
> automatically turn off the alternator field circuit. No split-master
> required. If you want to deactivate the alternator while leaving the
> battery on, you just pull the alternator field breaker. The alternator
> field was the only circuit breaker I had in my RV-4. Everything else
> was on fuse blocks, one for the main buss and one for the e-buss.
BTW, you can get high-current switches with low-current additional
poles. Usually these other poles are used to control a remote
indicator to tell someone the state of the switch. You can use one of
these other poles to control your alternator field circuit.
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
+1.340.998.9447 St. Thomas, VI 00802
There is a time to laud one's country and a time to protest. A good
citizen is prepared to do either as the need arises.
Message 5
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| Subject: | Electrical system ergonomics <LONG> |
--> AeroElectric-List message posted by: "James E. Clark" <james@nextupventures.com>
Excellent points Brian.
A couple of comments embedded. Actually several now. So this has gotten to
be long.
James
{SNIP}
>
> As someone who is working on the ergonomics of several different
> systems (not just aircraft) right now, I find the tendency toward
> complexity interesting. The first rule is to make normal operation as
> simple and obvious as possible. (I eschew the word 'intuitive' here as
> there is nothing intuitive about an airplane cockpit unless you are
> already a pilot.) Could your pilot buddy who has never flown your
> airplane before climb in and have a snowball's chance of making your
> electrical system work? If not, go back to the drawing board.
You are **SO** right here! I also believe if the system "cannot" be simple
then you must "hide" the complexity. Complexity should not reach out to the
user. In a former life one of my organizations was a "human interface
technology center". One cannot image how "non-intuitive" even a "simple" (to
someone who is already aware) system can be.
Funny, I used the same thinking ("... pilot buddy climb in ... snowball's
chance of making (it) work...") in panel layout and other stuff for our RV6.
Currently I have one label that technically needs changing and two that need
the words spelled out. Otherwise I think any "Cessna/Piper" pilot would be
able do just fine.
>
> Think about it. Why would you need external switches for things that
> have their own switches already? Joe 6-pack pilot knows that if he/she
> wants to turn off a radio he/she reaches up to the radio and turns off
> its power switch. No need to hunt around the cockpit for YAFS (yet
> another switch) and no additional point of failure.
Some people will though look for the "Avionics Master Switch" as that is
what they have become accustomed to.
>
> We spend so much time thinking about all the clever ways we want to
> have to deal with failure that we forget that it just doesn't happen
> often enough to try to streamline the process. Heck, think about your
> engine-out or aircraft fire litany. It just isn't all that simple and
> it involves much pushing, pulling, and switching but you manage anyway.
> Why should electrical system failure be any different. Here:
>
> Electrical system failure emergency checklist:
>
> 1. turn on e-buss switch;
>
> 2. turn off battery master switch;
>
> 3. turn off all unnecessary loads (usually extra radios) on the e-buss;
>
> 4. fly to a place where a landing may be effected most safely for
> troubleshooting.
>
> It just isn't all that difficult to do even in the heat of dealing with
> an emergency.
>
Though not an "emergency", I recall having an alternator failure some years
ago during a return FROM Sun-N-Fun. The real problem was that I did NOT know
it had happened until just before stopping about half-way home. When I went
to announce my position, someone came back and told me what a piece of junk
radio I had and they could not understand a thing. That got me trying to
figure stuff out as I **WANT** to be heard in this busy pattern. Basically
when I found I was short on juice, I just turned stuff off and landed with
an extra bit of pattern vigilance (along with my passenger looking out as
well).
> And one other thing about alternator failure. They don't fail all that
> often but when they do our tendency is to think that the failure is
> electrical in nature rather than mechanical. I had an alternator
> failure once that involved one of the bearings. The only symptom I had
> was that the alternator just dropped off-line. You see, the armature
> has started to wander around inside the case and had started to chew up
> the stator but there was no hint of that in the cockpit. If I had
> continued instead of landing the damage might have been much worse.
> Imagine the case of the alternator shattering and the armature merrily
> wandering around the engine compartment visiting all its friends in
> there.
Similar event but with a STARTER. Was about to take a mom and her kids for
an airplane ride (the mom was the "concerned" one). Spent a lot of time
talking about safety and its a "no-go" if even the slightest thing is out of
order. During taxi I notice a "low voltage" warning on my engine monitor
(added so I would not duplicate problem above :-) ). Told her about it and
said airplane will fly just fine here around the pattern even if there was
no alternator etc... BUT .... I said we are going back and check it "just to
be safe". Well I am so glad I did as when I taxied up, my friend immediately
had me SHUT DOWN! Lots of grinding noise from the starter (bendix??? hung?).
If I had run up the engine or maybe during takeoff I can imagine parts
flying everywhere. A mechanical problem that manifest itself as electrical
(the starter was pulling way more juice than the alternator wanted to
provide at the low taxi RPMs). Mis-diagnosed by me as electrical. Glad I
stopped to check the "electrical"problem.
James
>
> So even if you have all the continue-on capability you can design into
> your system, any sort of failure that could be construed as possibly
> being mechanical is grounds to get on the ground. The life you save me
> be that of your wallet.
>
> Brian Lloyd 6501 Red Hook Plaza
> brianl@lloyd.com Suite 201
> +1.340.998.9447 St. Thomas, VI 00802
>
> I fly because it releases my mind from the tyranny of petty things . . .
> Antoine de Saint-Exupry
>
>
Message 6
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| Subject: | Re: Electrical system ergonomics <LONG> |
--> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
On Dec 9, 2004, at 11:21 AM, James E. Clark wrote:
>> already a pilot.) Could your pilot buddy who has never flown your
>> airplane before climb in and have a snowball's chance of making your
>> electrical system work? If not, go back to the drawing board.
>
> You are **SO** right here! I also believe if the system "cannot" be
> simple
> then you must "hide" the complexity. Complexity should not reach out
> to the
> user. In a former life one of my organizations was a "human interface
> technology center". One cannot image how "non-intuitive" even a
> "simple" (to
> someone who is already aware) system can be.
Actually, I disagree on this point. As Albert Einstein once said,
"Everything should be made as simple as possible, but not simpler." If
something needs a knob, put the knob on the panel and label it. If
something needs a switch, put the switch on the panel and label it.
Hiding the complexity is the Microsoft, "don't worry your pretty little
head about it," approach to interface design. It works only if
everything is done exactly right. When there is a problem, people
can't find the necessary "switch" to help work around the problem.
> Funny, I used the same thinking ("... pilot buddy climb in ...
> snowball's
> chance of making (it) work...") in panel layout and other stuff for
> our RV6.
> Currently I have one label that technically needs changing and two
> that need
> the words spelled out. Otherwise I think any "Cessna/Piper" pilot
> would be
> able do just fine.
That is a good idea.
>> Think about it. Why would you need external switches for things that
>> have their own switches already? Joe 6-pack pilot knows that if
>> he/she
>> wants to turn off a radio he/she reaches up to the radio and turns off
>> its power switch. No need to hunt around the cockpit for YAFS (yet
>> another switch) and no additional point of failure.
>
> Some people will though look for the "Avionics Master Switch" as that
> is
> what they have become accustomed to.
But you don't want to turn everything off, just the things you don't
need at the moment. No one is going to try to turn off one radio by
turning off the avionics master switch.
Brian Lloyd 6501 Red Hook Plaza
brianl@lloyd.com Suite 201
+1.340.998.9447 St. Thomas, VI 00802
There is a time to laud one's country and a time to protest. A good
citizen is prepared to do either as the need arises.
Message 7
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| Subject: | Re: Electrical system ergonomics <LONG> |
--> AeroElectric-List message posted by: "Brian Sowell Home" <bsowell@digitex.net>
Still I haven't heard if there are any issues with putting a small, fused
jumper across the master contactor leads to keep a small current going
through the main EXP BUS lead to keep the Keep Alive tab hot. This was my
real question in my really long initial post. Any thoughts?
----- Original Message -----
From: "Brian Lloyd" <brianl@lloyd.com>
Subject: Re: AeroElectric-List: Electrical system ergonomics <LONG>
> --> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
>
> On Dec 9, 2004, at 11:21 AM, James E. Clark wrote:
>
>>> already a pilot.) Could your pilot buddy who has never flown your
>>> airplane before climb in and have a snowball's chance of making your
>>> electrical system work? If not, go back to the drawing board.
>>
>> You are **SO** right here! I also believe if the system "cannot" be
>> simple
>> then you must "hide" the complexity. Complexity should not reach out
>> to the
>> user. In a former life one of my organizations was a "human interface
>> technology center". One cannot image how "non-intuitive" even a
>> "simple" (to
>> someone who is already aware) system can be.
>
> Actually, I disagree on this point. As Albert Einstein once said,
> "Everything should be made as simple as possible, but not simpler." If
> something needs a knob, put the knob on the panel and label it. If
> something needs a switch, put the switch on the panel and label it.
> Hiding the complexity is the Microsoft, "don't worry your pretty little
> head about it," approach to interface design. It works only if
> everything is done exactly right. When there is a problem, people
> can't find the necessary "switch" to help work around the problem.
>
>> Funny, I used the same thinking ("... pilot buddy climb in ...
>> snowball's
>> chance of making (it) work...") in panel layout and other stuff for
>> our RV6.
>> Currently I have one label that technically needs changing and two
>> that need
>> the words spelled out. Otherwise I think any "Cessna/Piper" pilot
>> would be
>> able do just fine.
>
> That is a good idea.
>
>>> Think about it. Why would you need external switches for things that
>>> have their own switches already? Joe 6-pack pilot knows that if
>>> he/she
>>> wants to turn off a radio he/she reaches up to the radio and turns off
>>> its power switch. No need to hunt around the cockpit for YAFS (yet
>>> another switch) and no additional point of failure.
>>
>> Some people will though look for the "Avionics Master Switch" as that
>> is
>> what they have become accustomed to.
>
> But you don't want to turn everything off, just the things you don't
> need at the moment. No one is going to try to turn off one radio by
> turning off the avionics master switch.
>
> Brian Lloyd 6501 Red Hook Plaza
> brianl@lloyd.com Suite 201
> +1.340.998.9447 St. Thomas, VI 00802
>
> There is a time to laud one's country and a time to protest. A good
> citizen is prepared to do either as the need arises.
>
>
>
Message 8
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| Subject: | Electrical system ergonomics <LONG> |
--> AeroElectric-List message posted by: "James E. Clark" <james@nextupventures.com>
More comments ...
James
{SNIP}
> --> AeroElectric-List message posted by: Brian Lloyd <brianl@lloyd.com>
>
> On Dec 9, 2004, at 11:21 AM, James E. Clark wrote:
>
> >> already a pilot.) Could your pilot buddy who has never flown your
> >> airplane before climb in and have a snowball's chance of making your
> >> electrical system work? If not, go back to the drawing board.
> >
> > You are **SO** right here! I also believe if the system "cannot" be
> > simple
> > then you must "hide" the complexity. Complexity should not reach out
> > to the
> > user. In a former life one of my organizations was a "human interface
> > technology center". One cannot image how "non-intuitive" even a
> > "simple" (to
> > someone who is already aware) system can be.
>
> Actually, I disagree on this point. As Albert Einstein once said,
> "Everything should be made as simple as possible, but not simpler." If
> something needs a knob, put the knob on the panel and label it. If
> something needs a switch, put the switch on the panel and label it.
> Hiding the complexity is the Microsoft, "don't worry your pretty little
> head about it," approach to interface design. It works only if
> everything is done exactly right. When there is a problem, people
> can't find the necessary "switch" to help work around the problem.
>
Maybe we are on different pages here. The point I was trying to get across
goes something like this ...
Early cars had chokes, spark advances, mechanical starter linkages
(pushbutton with foot).
Now there is a much greater complexity about running the engine efficiently.
Clearly a lot of that could be "shared" with the user and a LOT of
adjustments could be made available for the user to deal with. In this case
we "hide" the complexity in an effort to "simply" the interaction.
So in that sense yes, I mean "don't you worry your little head about" all
the timing adjustments needed as you go from the flatlands in the desert at
100 degrees up the mountains to subzero temps at 10,000 feet. There is a lot
of complex stuff going on that you *might* feel you could improve on but
mabe not.
The same is true yes for Microsoft offerings to some extent and I agree with
that. It was also true to some extent with the various incarnations of the
UNIX OS and Linux variants. Many users don't care that much about the code
surrounding "pipes".
If I have several pieces of equipment in my plane and when things go bad I
want to get down to just the basics running, I don't think it is necessarily
bad to be able to throw a switch and have just the basics be running. That
is a variant of "hiding the complexity" to me.
Maybe this is just a point where we disagree. No big deal but good to have
the dialogue.
James
Message 9
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| Subject: | Electrical system ergonomics <LONG> |
--> AeroElectric-List message posted by: "James E. Clark" <james@nextupventures.com>
Sorry if I was not clear.
I think it will wok OK. Controlvision will give the definitive answer but I
infact did that, but **BEFORE** the contactor (the "hot" side ... directly
from the battery) and this has worked fine.
Of course the standard "your mileage may vary" applies.
James
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Brian
> Sowell Home
> Sent: Thursday, December 09, 2004 9:01 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Electrical system ergonomics <LONG>
>
>
> --> AeroElectric-List message posted by: "Brian Sowell Home"
> <bsowell@digitex.net>
>
> Still I haven't heard if there are any issues with putting a small, fused
> jumper across the master contactor leads to keep a small current going
> through the main EXP BUS lead to keep the Keep Alive tab hot. This was my
> real question in my really long initial post. Any thoughts?
>
> -{SNIP}
>
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