Today's Message Index:
----------------------
1. 06:51 AM - Re: Under Sized Wire (user9253)
2. 06:57 AM - Re: Wire Clamps (Robert L. Nuckolls, III)
3. 11:10 AM - Re: Re: Under Sized Wire (Roger)
4. 11:10 AM - Z13/8 with EarthX battery and dual electronic ignition (Mark and Kathleen Navratil)
5. 02:06 PM - Re: Wire Clamps (Art Zemon)
6. 08:12 PM - Re: Z13/8 with EarthX battery and dual electronic ignition (user9253)
Message 1
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| Subject: | Re: Under Sized Wire |
In reference to my original question about 14 AWG wire melting at 60 amp, below
are some links related to the subject.
Calculate the dissipated watts:
http://mustcalculate.com/electronics/wireproperties.php?mat=cu&l=1&area=2.08&areae=mm2&i=60&temp
All About Circuits forum discussion:
http://forum.allaboutcircuits.com/threads/how-to-calculate-heat-in-wires.108314/
WIRE AND CABLE MAXIMUM TEMPERATURE AND RISE IN AIR
DESIGN NOTE November 1996, Updated September 2009
by Douglas P. Arduini - Consultant
TABLE 3. MAXIMUM WIRE CURRENT FOR SINGLE COPPER WIRE IN FREE AIR
https://drive.google.com/open?id=0B7ZTG2VpCuDRR0VkRGpidG5DcTA
14 AWG at 43 amps = 125 degrees C temp rise
14 AWG at 47 amps =150 degrees C temp rise
14 AWG at 54 amps = 200 degrees C temp rise
Conclusion: 14 AWG wire would not melt at 60 amps
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=460028#460028
Message 2
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At 07:44 PM 8/29/2016, you wrote:
>That's a very clever idea. Thank you, Kent. I'll keep that one in
>mind. Given the way that the interior of the BD-4C is built, I am
>more likely to rivet a little piece of scrap to a an aluminum angle
>that is part of the frame than to use epoxy. But you have given me
>food for thought.
Adhesives in structural or semi-structural
applications are worthy of thought . . . and
testing.
Adhesive science is as much art as it is
physics. You can delve into the subject
on the 'net where you will discover discussions
on levels of energy inherent in the surfaces
of the various materials. The ability of an
adhesive to grip any given surface is a
function of surface textures and energy
levels diluted with the effects of shock,
moisture, contamination, temperature, etc. etc.
I would not discourage anyone from trying
any combination of glued joints using
materials from their past experiences
but if joint failure in your airplane
generates an uncomfortable level of
risk . . . well . . . think it through
and TEST.
At Beech, we had folks in the materials
lab who were dedicated to the study and
application of the various uckum-yuckies
that were offered up as the next great
glue. They could tell you some pretty
amazing stories . . . and as long as the
studies were confined to the lab, some were
funny too.
A few years ago I produce this article
for the 'Connection . . .
http://tinyurl.com/j2gxbqy
. . . and later, refined it for Kit Planes
http://tinyurl.com/hxczu3r
The article speaks to the use of glued-on
mountings for low-risk structural applications.
Securing wire bundles and small electro-whizzies
to the airplane are generally low risk
situations.
About the time I was selling the bond studs,
I researched a number of adhesives for their
suitability to task. No doubt there are many
but the material E6000 and "ShoGoo" proved
to be useful. The stuff needs 24 hour cure
but it's tenacious, robust, inexpensive
and available about everywhere.
Bob . . .
Message 3
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| Subject: | Re: Under Sized Wire |
WIRE AND CABLE MAXIMUM TEMPERATURE AND RISE IN AIR
DESIGN NOTE November 1996, Updated September 2009
by Douglas P. Arduini - Consultant
TABLE 3. MAXIMUM WIRE CURRENT FOR SINGLE COPPER WIRE IN FREE AIR
https://drive.google.com/open?id=0B7ZTG2VpCuDRR0VkRGpidG5DcTA
14 AWG at 43 amps = 125 degrees C temp rise
14 AWG at 47 amps =150 degrees C temp rise
14 AWG at 54 amps = 200 degrees C temp rise
Conclusion: 14 AWG wire would not melt at 60 amps
At 60 amps the temperature would be about 480 deg F!!
I would say that you would see some flowing of the wire
insulation and a bit of smoke. Not what I would call an
ideal airborne situation!
Roger
Message 4
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| Subject: | Z13/8 with EarthX battery and dual electronic ignition |
Hi Bob,
I'm building an RV-14A that will have a full glass IFR panel and dual elect
ronic ignition (still undecided about which brand of ignition but for discu
ssion purposes let's assume it's not P-mags). I'd also like to use the Ea
rthX ETX680 battery for the significant weight savings. Would you be comfo
rtable using Z13/8 for this mission?
A few specific questions I have:
1) 1) Is the SD-8 with the parallel R/C circuit & PMR1C-14 regulator
guaranteed to self-excite even if the alternator is brought online without
a battery connected? One possible failure mode is the physical connection
to the battery, but my real concern is the unknown failure modes of the Ear
thX technology. It's more complex than a lead acid battery due to the BMS
and newer chemistry and has a short track record thus far, so compared to a
n Odyssey PC680 I feel there's a greater chance that the EarthX may simply
shut itself off or fail in a manner that is equivalent to having the batter
y completely disconnected. In this scenario I would assume the main altern
ator will no longer function reliably so I need high confidence that the SD
-8 will come online and produce 12-14 V, especially with both ignition syst
ems depending on it.
2) 2) Operationally would you recommend having both alternators on al
l the time for normal flying? Or would you normally have the SD-8 off and
only switch it on if the main alternator fails? It seems one potential dow
nside to having both alternators on all the time is if there's an overvolta
ge condition it may trip the field breakers for both alternators. You woul
dn't know which one failed and you'd have to reset one CB at a time to see
which one works. Not a really big deal but it adds troubleshooting complex
ity...
3) 3) Z13/8 shows both electronic ignition systems connected to the M
ain Battery Bus. This seems ok for Pmags, but for ignition units without t
heir own generating capability, I'm thinking it would make sense to move on
e of them directly to the + battery terminal with a fusible link.
4) 4) Z13/8 shows the main battery lead, battery bus lead, and fuseli
nk for the SD-8 all connected to the same terminal on the battery contactor
. While I'm sure this is a pretty robust connection, it's still a potentia
l single point failure that could result in loss of your battery and both a
lternators (along with Main bus, E-bus, and Batt Bus) all at once. I'm thi
nking about moving the SD-8 fuselink from the battery contactor over to the
MAIN BATTERY BUS fuseblock stud. This would look the same to the electron
s but eliminates the battery contactor stud as a single point failure for t
he entire system. Thoughts?
I know I could alleviate some of my concerns by going with an Odyssey PC680
and installing magnetos or Pmags, but the Odyssey battery is significantly
heavier and the Pmags are still a concern for long-term reliability (I'm s
keptical about how any electronic device can handle the heat exposure that
is inherent in the Pmag design and have an MTBF of more than several hundre
d hours). I could also add another smaller battery and have a full dual ba
tt/dual alternator architecture, but this adds more weight, complexity, mai
ntenance, expense, etc, so I prefer not to go that route unless necessary.
Thanks,
Mark Navratil
Spring Hill, KS
RV-8A N2D built/flew/sold
RV-14A #140017 finishing wings
Message 5
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More good ideas. Thank you, Bob.
Everybody: This is hugely helpful. I won't use all of these ideas but just
seeing the photos is giving me ideas that I can build on. Some of the
places that I want to secure wires would have been a PITA with cushion
clamps.
-- Art Z.
On Tue, Aug 30, 2016 at 8:54 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 07:44 PM 8/29/2016, you wrote:
>
> That's a very clever idea. Thank you, Kent. I'll keep that one in mind.
> Given the way that the interior of the BD-4C is built, I am more likely to
> rivet a little piece of scrap to a an aluminum angle that is part of the
> frame than to use epoxy. But you have given me food for thought.
>
>
> Adhesives in structural or semi-structural
> applications are worthy of thought . . . and
> testing.
>
> Adhesive science is as much art as it is
> physics. You can delve into the subject
> on the 'net where you will discover discussions
> on levels of energy inherent in the surfaces
> of the various materials. The ability of an
> adhesive to grip any given surface is a
> function of surface textures and energy
> levels diluted with the effects of shock,
> moisture, contamination, temperature, etc. etc.
>
> I would not discourage anyone from trying
> any combination of glued joints using
> materials from their past experiences
> but if joint failure in your airplane
> generates an uncomfortable level of
> risk . . . well . . . think it through
> and TEST.
>
> At Beech, we had folks in the materials
> lab who were dedicated to the study and
> application of the various uckum-yuckies
> that were offered up as the next great
> glue. They could tell you some pretty
> amazing stories . . . and as long as the
> studies were confined to the lab, some were
> funny too.
>
> A few years ago I produce this article
> for the 'Connection . . .
>
>
> http://tinyurl.com/j2gxbqy
>
> . . . and later, refined it for Kit Planes
>
> http://tinyurl.com/hxczu3r
>
> The article speaks to the use of glued-on
> mountings for low-risk structural applications.
> Securing wire bundles and small electro-whizzies
> to the airplane are generally low risk
> situations.
>
> About the time I was selling the bond studs,
> I researched a number of adhesives for their
> suitability to task. No doubt there are many
> but the material E6000 and "ShoGoo" proved
> to be useful. The stuff needs 24 hour cure
> but it's tenacious, robust, inexpensive
> and available about everywhere.
>
>
> Bob . . .
>
--
http://CheerfulCurmudgeon.com/ <http://cheerfulcurmudgeon.com/>
*"If I am not for myself, who is for me? And if I am only for myself, what
am I? And if not now, when?" Hillel*
Message 6
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| Subject: | Re: Z13/8 with EarthX battery and dual electronic ignition |
The Rotax 914 fuel injected engine has two alternators: the permanent magnet one
and the larger electromagnet (wired field) one. The permanent magnet dynamo
is completely separate from the aircraft electrical system and is dedicated to
powering a fuel pump only. No matter how the aircraft electrical system fails,
the fuel pump will keep working as long as the engine is running.
The SD-8 could be wired similar to the Rotax dynamo.
An AGM lead battery is unlikely to short out. Is it possible for the EarthX to
short out and bring down the whole aircraft electrical system?
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=460059#460059
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