Today's Message Index:
----------------------
1. 08:06 AM - Battery Disconnect Switch... (Steve Stearns)
2. 08:14 AM - Re: Unprotected Feeder in Z Drawings (Richard Girard)
3. 08:28 AM - Re: Battery Disconnect Switch... (Steve Stearns)
4. 08:51 AM - Re: Unprotected Feeder in Z Drawings (Robert L. Nuckolls, III)
5. 09:05 AM - Re: Battery Disconnect Switch... (Robert L. Nuckolls, III)
Message 1
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| Subject: | Battery Disconnect Switch... |
Greetings,
I'm working on the wiring for a Solitare and it uses a small engine (KFM
Maxi 107) with only a 300W starter. I'm shopping for an appropriate
disconnect switch (in lieu of a master relay) that is capable of
disconnecting the starter current should the starter relay get stuck.
I don't know much about the starter motor other than the 300W listed in
the engine manual (PM? series wound?) but given the 300W it seems like
100A disconnect capable switch should be more than enough when taking
into account battery sag and motor inefficiency. However, if anyone has
a defensible way to come up with a better number, I'd love to hear it.
I'm looking for the physically smallest switch that is up to the task.
Does anyone have an suggestions an appropriate switch? The usual
race-car style battery disconnects are way over-kill and physically
quite large as a result.
All thoughts appreciated,
Steve Stearns
Boulder/Longmont, Colorado
Restoring (since 1/07) and flying again (8/11!): N45FC O235 Longeze
Cothern/Friling CF1 (~1000 Hrs)
Flying (since 9/86): N43732 A65 Taylorcraft BC12D
Message 2
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| Subject: | Re: Unprotected Feeder in Z Drawings |
Bob, I think I understand the exercise, but I don't understand the solution
in search of a problem. As I learned it the decision tree looks like this;
1. Is there a problem?
2. How big is the problem?
3. Is there a need to craft a solution to the problem?
4. What is the payback, in terms of increased safety, of the solution?
In this case, it seems to me, the answer to 1. is no. Where does this
decision tree go from there?
If the only instance of a problem is caused by a loose object in the
cockpit, is not training or even a cockpit placard to "secure all loose
items before aerobatic flight" a better solution than a feeder line fuse?
Rick
do not archive
On Sun, Dec 8, 2013 at 6:28 PM, Jeff Luckey <jluckey@pacbell.net> wrote:
>
> Rick,
>
> Normally I wouldn't waste my time to respond to such an unenlightened post
> but you are way out of line here.
>
> If you are unable to understand the engineering nuances being discussed in
> this thread then I suggest you just delete or ignore them. Or maybe you
> should read them, you might learn something.
>
> And please take your own advice
>
> "The amount of bandwidth being devoted to this (not to mention uselessly
> tied up storage on Matt's servers) is absolutely ridiculous. "
>
> and spare The List your reply to this message - as that would certainly be
> a waste of
> bandwidth. The members certainly don't want to watch you and me exchange
> barbs.
> I just added your email address to my spam filter so I will never see them.
>
> Now I feel smug
>
>
> do not archive
>
> ------------------------------
> *From:* Richard Girard <aslsa.rng@gmail.com>
> *To:* aeroelectric-list@matronics.com
> *Sent:* Sunday, December 8, 2013 7:54 AM
> *Subject:* Re: AeroElectric-List: Unprotected Feeder in Z Drawings
>
> Jeff, I'm pretty sure that as you look to more and more outliers in order
> to find a problem to which you can fit your solution that it's just getting
> silly. Put the damn fuse in your feeder wire, feel smug, and PLEASE move
> on. The amount of bandwidth being devoted to this (not to mention uselessly
> tied up storage on Matt's servers) is absolutely ridiculous.
> And guys, the phrase "do not archive" below your signature will go a long
> way toward reducing the clutter.
>
> Rick Girard
> do not archive
>
>
> On Sun, Dec 8, 2013 at 7:28 AM, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
> At 06:28 PM 12/7/2013, you wrote:
>
> There is an interesting psychological factor that I've heard called "risk
> compensation" that applies here.
>
>
> Yes . . . and there are documented examples of this
> phenomenon that goes back to the beginnings of
> recorded history. I remember discussions at Cessna
> wayyyyy back when that centered on pilot attitudes
> toward risk of icing after they had boots and heated
> windshield patches installed on their airplanes.
>
> The ability to mitigate a risk can have a down-side
> for making one less considerate of the risk. The
> same things are happening in the cockpit when
> modern electronics 'replaces' abilities to dead-reckon,
> contact-navigate with maps, etc.
>
> It's easy to forget that the only thing standing
> between a pilot and a need to resurrect and practice
> such skills is a pin pushed back in a connector
> or a poorly crimped terminal.
>
>
> Bob . . .
>
> *
>
> _blank">www.aeroelectric.com <http://www.aeroelectric.com>
> .com" target="_blank">www.buildersbooks.com <http://www.buildersbooks.com>
> ="_blank">www.homebuilthelp.com <http://www.homebuilthelp.com>
> ="_blank">www.mypilotstore.com <http://www.mypilotstore.com>
> ank">www.mrrace.com <http://www.mrrace.com>
> _blank">http://www.matronics.com/contribution <http://www.matronics.com/contribution>
> ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List <http://www.matronics.com/Navigator?AeroElectric-List>
> tp://forums.matronics.com <http://forums.matronics.com>
> *
>
>
> --
> Zulu Delta
> Mk IIIC
> Thanks, Homer GBYM
>
> It isn't necessary to have relatives in Kansas City in order to be unhappy.
> - Groucho Marx
>
> *www.mypil===============
> *
>
>
> *
>
> *
>
>
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
Message 3
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| Subject: | Re: Battery Disconnect Switch... |
Related question: How much do you have to de-rate the combined current
handling if you wire a DPST with the poles in parallel? I'm assuming if
you have a 30A DPST toggle switch (which I've found. Big, but not as big
as a battery disconnect switch) and you wire the poles in parallel, the
appropriate rating is something less than 60A. Anyone know?
Thanks,
Steve.
On 12/9/2013 9:05 AM, Steve Stearns wrote:
> Greetings,
>
> I'm working on the wiring for a Solitare and it uses a small engine
> (KFM Maxi 107) with only a 300W starter. I'm shopping for an
> appropriate disconnect switch (in lieu of a master relay) that is
> capable of disconnecting the starter current should the starter relay
> get stuck.
>
> I don't know much about the starter motor other than the 300W listed
> in the engine manual (PM? series wound?) but given the 300W it seems
> like 100A disconnect capable switch should be more than enough when
> taking into account battery sag and motor inefficiency. However, if
> anyone has a defensible way to come up with a better number, I'd love
> to hear it. I'm looking for the physically smallest switch that is up
> to the task.
>
> Does anyone have an suggestions an appropriate switch? The usual
> race-car style battery disconnects are way over-kill and physically
> quite large as a result.
>
> All thoughts appreciated,
>
> Steve Stearns
> Boulder/Longmont, Colorado
> Restoring (since 1/07) and flying again (8/11!): N45FC O235 Longeze
> Cothern/Friling CF1 (~1000 Hrs)
> Flying (since 9/86): N43732 A65 Taylorcraft BC12D
>
Message 4
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| Subject: | Re: Unprotected Feeder in Z Drawings |
At 10:13 AM 12/9/2013, you wrote:
>Bob, I think I understand the exercise, but I don't understand the
>solution in search of a problem. As I learned it the decision tree
>looks like this;
>
>1. Is there a problem?
>2. How big is the problem?
>3. Is there a need to craft a solution to the problem?
>4. What is the payback, in terms of increased safety, of the solution?
>
>In this case, it seems to me, the answer to 1. is no. Where does
>this decision tree go from there?
>If the only instance of a problem is caused by a loose object in the
>cockpit, is not training or even a cockpit placard to "secure all
>loose items before aerobatic flight" a better solution than a feeder line fuse?
The FMEA is not looking for a solution to a problem,
it's a sifting of simple-ideas looking for potential
elevations of risk.
The sifting of anecdotes is also a valuable exercise.
The potential for increased risk from loose, conductive items
was offered. I shared some simple-ideas about the
nature of high-quality joining of wires that gave
pause for considering the integrity of the story.
This is all about the science and forensics . . .
from which decisions might flow that solves
a "problem".
You're right, we've yet to identify a problem.
But the tools being exercised here have broad
applicability and should be practiced whether
or not a problem emerges that begs a solution.
Bob . . .
Message 5
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| Subject: | Re: Battery Disconnect Switch... |
At 10:05 AM 12/9/2013, you wrote:
>
>Greetings,
>
>I'm working on the wiring for a Solitare and it uses a small engine
>(KFM Maxi 107) with only a 300W starter. I'm shopping for an
>appropriate disconnect switch (in lieu of a master relay) that is
>capable of disconnecting the starter current should the starter
>relay get stuck.
>
>I don't know much about the starter motor other than the 300W listed
>in the engine manual (PM? series wound?) but given the 300W it
>seems like 100A disconnect capable switch should be more than enough
>when taking into account battery sag and motor inefficiency.
>However, if anyone has a defensible way to come up with a better
>number, I'd love to hear it.
>I'm looking for the physically smallest switch that is up to the task.
>
>Does anyone have an suggestions an appropriate switch? The usual
>race-car style battery disconnects are way over-kill and physically
>quite large as a result.
>
>All thoughts appreciated,
Hi Steve,
It's been a long time since we've chatted.
Consider this item from Summit Racing
Emacs!
It's their SUM-G1432
It's 'rated' with some pretty sedate currents
as a switch . . . but your switching requirements
are benign also. I'd bet this switch will CARRY
the starter currents just fine.
In any case, the price is right (about $20) and
the size is attractive too. There's also a Moroso
74101 that is about the same size and RATED for
much greater currents. A tad more expensive too
at $45 but almost certain to be suited to
the task. See:
http://tinyurl.com/kj5jwba
Bob . . .
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