Re: Web page update - Wiring


Joseph M Snow <1flashq@...>
 

John,

Excellent commentary. I have already made a copy of your email and placed it on my "to do"clipboard.

I like the idea of labeling the wires. I do not understand how you could read such a lable wrapped around a 22 awg wire. The information might be read if it were printed as a long sentence, about 1-2 "...? Is this what you have in mind?

Joseph

johntenhave <johntenhave@...> wrote:
Joseph,

Good work. Your web site is an excellent illustration of the
observation that a home built aircraft project can be divided into 1/3
of the time for airframe, 1/3 for systems and 1/3 for finishing (and
maybe another 1/3 for documenting ;-))

Some comments for you to consider:

Depending upon the airflow the alternator may provide asymmetric
cooling airflow to the cylinders. Radiant heat may also affect the
reliability of the alternator. Locating it at 90 degrees would fix that..

As you have illustrated the wiring grows like topsy, and as you build
your looms wire by wire it all seems crystal clear. However, come fix
it time at some remote field, the lack of consistent labeling is going
to make it tough. (read : the avionic guy has just been handed an open
cheque.) Particularly when all the wires are considerately colour
coded white for simplicity..

Flippant question: how many folk carry a wiring diagram with them when
flying? Show of hands? Quick count? Answer, almost one..

Here is an alternative. When you do your wiring design (this did
happen first didn't it?) (Idle question: Do the terms essential buss
and auxiliary buss mean anything?) There are obvious places to put
test points, terminal blocks, multi-pin quick release sockets etc
which feature on your wiring diagram. An hour of effort can result in
a listing of all the wires.

First a quick diversion :

Each wire has two ends, and it goes from somewhere to somewhere. When
I addressed this issue my aim was deceptively simple and it was this:

To be able to pick up any wire, without any wiring diagram, and know
where it came from and where it was going.

OK how to do it? Simple. Recall our list of wires and lets take an
example :

Instrument lighting

A wire runs from the instrument lighting circuit breaker, to the
terminal block, from the terminal block to the dimmer, from the dimmer
to the light +ve and from the light -ve to earth.

So the ideal would be to label each wire saying just that. One method
which works really well is to laser print up on plain white paper (in
6pt arial) the following labels:

Inst CB to TB 2-3
TB 2-3 to Dimmer R
Dimmer B to Inst L +
Inst L - to E

Inst CB to TB 2-3
TB 2-3 to Dimmer R
Dimmer B to Inst L +
Inst L - to E

Notice we have printed them twice? That is because there are two ends.

TB 2-3? terminal block 2, terminal 3.

Dimmer R? Dimmer Red

Dimmer B? Dimmer Black

Have a system that is logical eg red at the higher potential, black
at the lower..

Next, get clear heat shrink. Cut each label out. Cut a length of heat
shrink 1/4"longer. Strip the wires and slip the label on to each end.
Cover it with heat shrink and shrink it on, leaving enough bare
insulation to complete the termination (twice).

While I was working this out, I carried a sample around in my shirt
pockets for week or so. Eventually I forgot to take it out and through
the washing machine it went. A week of submersion later when I
recovered it, no degradation. So I can now wander with impunity
around my Long Eze, multimeter in hand and know what I am measuring
and where.

Re batteries, why are you not using an Odyssey Battery, and why is it
so far from where it needs to be to do its work? CofG I suspect..

Batteries go flat. Verify that it is easy to get a set of jumper leads
onto your battery without removing the tail-cone. You might want to
consider a light weight socket(which runs to the outside of the
airframe,underneath the fuselage)and carry a custom plug with short
flying leads. Make them different lengths.

Check your unsupported lengths of wire - 10" maximum (look down your
left hand side foot well). Speaking of footwells, some of your wires
running to your common ground are very vulnerable to being stomped on.
A cover would be smart.

When your wires pass through bulkheads, grommet them or p clip them
and make the hole bigger, otherwise they will chafe through..not now,
not tomorrow, but soon. You did great work on the firewall and then
downstream - the music seemed to stop...

You also have a lot of spade terminals which are mighty close to the
firewall. Give some thought to a garden hose being sprayed through
the intake. Dust, grime and other conductive grime build up - do you
still have electrical isolation? Think about dropping a spanner into
the works....

Speaking of failures, most wiring faults occur at the terminals so it
is cheap insurance to ensure that you have enough slack in every wire
to be able to re-terminate if required. If you are really forward
thinking running an extra pair of wires or so from terminal block to
terminal block can be a life saver come modification time..

Think about loctiting your screws into the terminal blocks otherwise
vibration may back them out...oops!

Speaking of dropping, make sure you mount your contactors
horizontally, so that shock loadings do not trigger inadvertent
starter operation - the starter flashing up during a series of PIOs is
not component life prolonging. Neither is the master switch cutting in
and out.

On your next iteration, lose the solid instrument panel and put in
removable subpanels. We can talk about how to do that another time.

You have done lots of good work and you are well on the way to doing
a super job. You will be able to nip down to the nearest pilot
supplies and buy a set of Captain's rank slides in no time flat.

Hope this helps

John

--- In Q-LIST@..., Joseph M Snow <1flashq@...> wrote:

Hello Q-listers,

Here is another update of my web pages. This page is on the
electrical system. I received a number of helpful comments from my
previous update. Thank you! I am hoping you are still willing to
"look over my sholders" at this electrical system. While compiling
the page and thinking through what I had done, I found several issues
that I wanted to clean up. Perhaps you will see something I did not
see. Please let me know about it.

Here is the link: http://corvairq.info/Electrical.htm

Joseph Snow,
Q2xx, N240JS



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