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nuckolls.bob(at)aeroelect
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 Posted: Tue Jun 22, 2010 7:32 pm Post subject: Z-13 Alternator & Starter Wire Size |
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At 09:53 PM 6/22/2010, you wrote:
| Quote: |
After looking at a copper wire resistance chart and playing with
V=DIR, it seems as if the 4AWG callout on Z-13 for the B lead is
overkill for a 60 amp alternator and even for the start circuit.
For the alternator, wouldn't 10AWG be sufficient for a 1' run to
the starter contactor? Voltage drop= 1' x 60a x .00118, or .07v
And could the 2'start circuit for my 1.5kw starter (125a (at) 12v) be
comfortable with losing .12v using 6awg .12v=1' x 125a x .000465?
Just checking with you all to make sure that I'm not overlooking
something in trying to keep my plane on a diet.
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Your doing just fine for a design goal that
has weight very high up on the list of priorities . . .
Having offered that, total weight savings is
pretty small. If I were building an airplane
where the battery, alternator and starter were
all within say 3 feet of each other, I'd wire
with 4AWG for all the fat wires and exploit
the single source of inexpensive wire.
Keep in mind too, temperature rise. THATS what
really limits the wire's current carrying
abilities . . .it's the insulation that dies
first, the copper is good for a whole lot more.
That 4AWG welding cable is pretty attractive.
For the few ounces of difference I'd probably
be better off cutting back a tad on the Big Macs.
But that's just me . . .
Bob . . .
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jonlaury
Joined: 06 Nov 2006
Posts: 336
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| Posted: Wed Jun 23, 2010 6:20 am Post subject: Re: Z-13 Alternator & Starter Wire Size |
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[/quote]
Your doing just fine for a design goal that
has weight very high up on the list of priorities . . .
Having offered that, total weight savings is
pretty small. ....
Bob . . .[/quote]
Of course I did my analysis [i]after[/i] I bought the wire and terminals, so your recommendation is music to my ears  And I can't argue about the difference in weight as all my wire runs are pretty short.
But somewhere a long time ago when I started this project, I read (and was never able to shake it) the maxim re building planes: " During the building journey, if one takes care to eliminate extra ounces, the extra pounds will take care of themselves at completion"
J
Do not archive
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nuckolls.bob(at)aeroelect
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| Posted: Wed Jun 23, 2010 9:39 am Post subject: Z-13 Alternator & Starter Wire Size |
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| Quote: | But somewhere a long time ago when I started this project, I read
(and was never able to shake it) the maxim re building planes: "
During the building journey, if one takes care to eliminate extra
ounces, the extra pounds will take care of themselves at completion"
|
yeah . . . sort of. When Burt Rutan did the Voyager
project, he had an airplane that grossed about 12000
pounds at takeoff. It took about 5 pounds of fuel
to carry 1 pound of airplane around the world. Needless
to say, paying attention to empty weight was mission
critical.
I think most of us fly for fun. We pile 'stuff' into
the airplane including our bods that varies from
mission to mission . . . and few of us figure fuel
endurance down to the last gallon. Further, the
average use of a light aircraft in the US is 50
or so hours per year. If it were a revenue generating
hauler that flew 50 hours a month, then one MIGHT
be able to make a case for fine-tuning the ship's
empty weight.
My feeling is that time would be better spent
on the craftsmanship of the assembly than on
bean-counting (or ounce-counting).
Bob . . .
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jonlaury
Joined: 06 Nov 2006
Posts: 336
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| Posted: Wed Jun 23, 2010 12:10 pm Post subject: Re: Z-13 Alternator & Starter Wire Size |
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| nuckolls.bob(at)aeroelect wrote: |
... then one MIGHT
be able to make a case for fine-tuning the ship's
empty weight.
My feeling is that time would be better spent
on the craftsmanship of the assembly than on
bean-counting (or ounce-counting).
Bob . . . |
My thrust in this project has been to try something a little different to get a better result. Glasairs, with a high wing loading, are pretty weight sensitive and, to boot, I stuck a bigger engine than normal in mine. I figured with a composite prop(-30#) and losing the nose gear(-30#), I could compensate for a little more engine weight (and hp). Knowing that I'd handicapped myself with the engine, I've tried to save weight everywhere I can. That drove the decision for an aux alternator over an aux battery for a 5# wt. saving.
But in the end, I want a daily flyer (or weekly) that is finely crafted, that I don't have to tinker with constantly, is a blast to fly and that my wife finds comfortable (well, me too). So it's easy to go with a few extra ounces of copper if it means that my starter has an easy life, my ground power circuit will happily start my engine after I've left the master on, and generally that the electrons in my system find the race track empty and cool all the time.
Through the AEL and your thoughtful advice, I think I am well on my way to accomplishing my goal.
John
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Allen Fulmer
Joined: 10 Jan 2006
Posts: 79
Location: Alexander City, AL
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| Posted: Wed Jun 23, 2010 6:26 pm Post subject: Z-13 Alternator & Starter Wire Size |
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I like that Bob. I am going to quit feeling guilty for adding all those
gadgets that I think I will enjoy. Those seat heaters, O2, etc., will feel
just right at 16,000 feet as I fly over the Rockies on my way around the
Western US.
Allen Fulmer
RV7 Turbo Normalized Subaru
3 screen GRT EFIS, autopilot, etc.
Alexander City, AL
--
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_________________
RV7 QB Fuselage
Eggenfellner H6 on orde
N808AF reserved
Alexander City, AL |
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BobsV35B(at)aol.com
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| Posted: Wed Jun 23, 2010 7:44 pm Post subject: Z-13 Alternator & Starter Wire Size |
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Good Evening Allen and 'Lectric Bob,
I tend to agree with the thought that we should always remain weight conscious.
If you want seat heaters, put them in, but make sure they are efficient and light weight. An ounce here and an ounce there may not seem like much, but each ounce should be serving a purpose.
No doubt that cost is always going to be a factor.
I like the phrase quoted. ---- "During the building journey, if one takes care to eliminate extra
ounces, the extra pounds will take care of themselves at completion"
I am an avowed Bonanza nut. The main reason the early Bonanza did as well as it did was due to the "save an ounce everywhere you can" spirit with which the straight 35 was built. It way out performed everything else of the era because it was a couple of hundred pounds lighter.
The effort does pay off.
Enjoy all the comforts you want, but don't waste any weight on something you don't need.
Happy Skies,
Old Bob
In a message dated 6/23/2010 9:27:30 P.M. Central Daylight Time, afulmer(at)charter.net writes:
| Quote: | --> AeroElectric-List message posted by: "Allen Fulmer" <afulmer(at)charter.net>
I like that Bob. I am going to quit feeling guilty for adding all those
gadgets that I think I will enjoy. Those seat heaters, O2, etc., will feel
just right at 16,000 feet as I fly over the Rockies on my way around the
Western US.
Allen Fulmer
RV7 Turbo Normalized Subaru
3 screen GRT EFIS, autopilot, etc.
Alexander City, AL
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, June 23, 2010 12:42 PM
To: aeroelectric-list(at)matronics.com
Subject: Re: Re: Z-13 Alternator & Starter Wire Size
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<nuckolls.bob(at)aeroelectric.com>
| Quote: | But somewhere a long time ago when I started this project, I read
(and was never able to shake it) the maxim re building planes: "
During the building journey, if one takes care to eliminate extra
ounces, the extra pounds will take care of themselves at completion"
|
yeah . . . sort of. When Burt Rutan did the Voyager
project, he had an airplane that grossed about 12000
pounds at takeoff. It took about 5 pounds of fuel
to carry 1 pound of airplane around the world. Needless
to say, paying attention to empty weight was mission
critical.
I think most of us fly for fun. We pile 'stuff' into
the airplane including our bods that varies from
mission to mission . . . and few of us figure fuel
endurance down to the last gallon. Further, the
average use of a light aircraft in the US is 50
or so hours per year. If it were a revenue generating
hauler that flew 50 hours a month, then one MIGHT
be able to make a case for fine-tuning the ship's
empty weight.
My feeling is that time would be better spent
on the craftsmanship of the assembly than on
bean-counting (or ounce-counting).
Bob . . . ========================= = Use utilities Day ================================================ - MATRONICS WEB FORUMS ================================================ - List Contribution Web Site sp; ===================================================
|
[quote][b]
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