Today's Message Index:
----------------------
1. 05:55 AM - Re: Insulated ground cables? (Robert L. Nuckolls, III)
2. 01:36 PM - Alternator/regulator (Gary Burdett)
3. 02:51 PM - Power Generation without Battery? (Chris Mullins)
4. 03:20 PM - Re: Power Generation without Battery? (Ben)
5. 03:42 PM - Re: Power Generation without Battery? (Peter Pengilly)
6. 05:58 PM - Re: Insulated ground cables? (David Saylor)
7. 06:35 PM - Re: Power Generation without Battery? (Jeff Luckey)
Message 1
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| Subject: | Re: Insulated ground cables? |
>Hi Bob et al.
>
>The fuel line is conductive aluminium - why would there be a static
>build up, unless it were isolated completely from the rest of the
>airframe by rubber fittings at every support as well as rubber hoses
>connecting it to the rest of the fuel system? Surely no matter where
>the pipe is grounded (by connecting it to the fuel tank, gascolator,
>fuel selector switch or similar), that would dissipate any static
>build up along the entire length of aluminium piping and anything
>else connected to it by the AN fittings? I am particularly intrigued
>by this having _just_ ordered 50' of aluminium fuel piping to refit
>my Citabria's continuously perishing rubber fuel hoses.
Not a static built up WITHIN the tube, but static
currents circulating WITHOUT wherein two conductive
entities are not electrically bonded to each others
and some 'discharge' occurs between them. This is
not a fire safety kind of issue but purely one of
potential noise.
Admittedly, this is an stretch in the extreme to
apply this kind of reasoning to 99 percent of little
airplanes . . . but there are folks who have listened
well to their teachers with experience in high performance,
high altitude and perhaps weapons-grade machines
wherein the slightest risk for mission failure was
treated as a national security issue.
The question that Dave was pondering is probably
not germane to any airplanes that we're interested
in . . . and the narrative supporting the practice
for what he is observing is not readily available
to us.
It's interesting to ponder the value of many of the
process specifications I've encountered over the
years. Beech and Cessna had libraries of them. If
there's a failing of requirements laid out in hard
document (or cultural rules-of-thumb), it's the
dearth of background for why some things are a good
idea and under what conditions they should . . . or
need not be applied.
The authors were long gone and could not be queried
as to the foundation for the practice. Hence, things
that may have been done in good faith and sound
physics on some project years ago have been filtered
down as part of the cultural boiler-plate; dutifully
honored to this day . . . sometimes as more of a
religion than a science. Sorta like the cultural
obsession with oil pressure during the first seconds
of an engine start. Charles Lindbergh may have personally
experience broken oil circulation systems or perhaps
his associates had personal experiences . . . but
what is the likelihood of such an event today?
Most automobiles are fitted with oil pressure switches
that kill the fuel pump when no pressure is sensed.
This prevents a tank mounted pump from driving a
broken fuel line after the engine stops from fuel
starvation. The engine is more likely the become 'inop'
due to fuel plumbing problems (or shorted bus feeder
or smoked electrical system) than for lack of lubrication.
>Could it not be as a mechanical restraint in the event of an
>accident to ensure that when the airframe crumples the pipe bends in
>a particular fashion to reduce the risk of kinking and spraying fuel
>all over a fire...?
Without published background for a particular
practice, we'll never know for sure. But I think
it's more simplistic. AC43-13 focus is on robust
mounting with allowances for necessary movement while
maintaining clearances between antagonistic components
and mitigating the effects of environment.
The astute systems installer views power steering
hoses, fuel lines, brake lines, control cables,
wire bundles, and all manner of moving parts as
potential antagonists against each other. The
art of their craft includes a running narrative
FMEA pondering all the ways these components may fail
to function due to interference by another component
combined perhaps with an environmental stress.
I used to field worrisome questions about 'exposed'
bus bars behind the panel with the following: "Okay,
with your choice of hammers, saws, clippers or
any other tool, crawl under the panel and do
what ever it takes to bring some part of your
airplane against that exposed bus bar. If you
find some component at risk for such interference,
what is the likelihood of that happening in flight?
If there is strong likelihood, is it better to shield
the bus . . . or improve on the mounting and robustness
of the interfering part?"
From narratives like this . . . and lessons learned
. . . that process specs are crafted and become part of
THE WORD . . . a word often adopted on faith
after the supporting narrative is lost to history.
But we can hone our own awareness of risks by
constantly reviewing the capabilities, limits
and vulnerabilities of components we bolt to our
airplanes. When you bolt in a nice, new, feather
light lithium battery, you ponder . . . "Gee, is
this little feller going to be happy in my airplane?"
When you bundle a bus feeder line together with
come control cables . . . "Hmmmmm . . . can those
guys get each other into trouble like squabbling
two-year-olds?"
The potential for problematic combinations
is huge but they're all based on exceedingly simple
ideas with risks for failure to sift through
the beans for pebbles . . . before the pot goes
on the stove.
Bob . . .
Message 2
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| Subject: | Alternator/regulator |
I have a JD/yanmar PM alternator and regulator with crowbar circuit. Voltage was
starting to run over 15 volts at cruise rpms. Replaced battery and regulator,
now hits 15.5 volts at anything over 2400 rpms on first test with a fully charged
battery..????
Sent from my iPad
Message 3
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| Subject: | Power Generation without Battery? |
Bob,
I am building a Carbon Cub - a lightweight experimental design for
backcountry use. It will use a fully electrically dependent Lycoming
engine. I plan on 1 battery/2 alternators, and I desire the system to run
the engine with any 1 of those 3 failed.
I want to use a lithium battery for starting purposes only. I am not
worried about battery only endurance with 2 other power sources.
Alternator technology is mature, but Li batteries seem to be still
evolving. Some type of battery fault would seem be a likely failure mode in
my planned system. (I'd like to monitor battery temp using a probe and my
on board electronics, and to have some way to electrically isolate or even
physically remove the battery).
I plan to use your Z12 or Z13 architecture.
People I speak with advise me that alternators (even the SD8) are dependent
on a functioning battery in the system, and that they will cease to
function if the battery fails or is taken offline.
Recent revelations regarding the Challenger/Aerovoltz scenario aside, there
seem to still be legitimate issues with the current Li crop. At the very
least they remain relatively unproven.
So I am concerned about the Li battery being a single point of failure
capable of stopping the engine.
How can I design around this problem?
Chris M
Message 4
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| Subject: | Re: Power Generation without Battery? |
Pmag ????? Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: Chris Mullins <mullincl@gmail.com>
Subject: AeroElectric-List: Power Generation without Battery?
Bob,
I am building a Carbon Cub - a lightweight experimental design for backc
ountry use. It will use a fully electrically dependent Lycoming engine.
I plan on 1 battery/2 alternators, and I desire the system to run the en
gine with any 1 of those 3 failed.
I want to use a lithium battery for starting purposes only. I am not wor
ried about battery only endurance with 2 other power sources.
Alternator technology is mature, but Li batteries seem to be still evolv
ing. Some type of battery fault would seem be a likely failure mode in m
y planned system. (I'd like to monitor battery temp using a probe and my
on board electronics, and to have some way to electrically isolate or e
ven physically remove the battery).
I plan to use your Z12 or Z13 architecture.
People I speak with advise me that alternators (even the SD8) are depend
ent on a functioning battery in the system, and that they will cease to
function if the battery fails or is taken offline.
Recent revelations regarding the Challenger/Aerovoltz scenario aside, th
ere seem to still be legitimate issues with the current Li crop. At the
very least they remain relatively unproven.
So I am concerned about the Li battery being a single point of failure c
apable of stopping the engine.
How can I design around this problem?
========================
========================
========================
========================
========================
=========
____________________________________________________________
The Next Big Thing
3 Companies Running Big Cable Out of Business
http://thirdpartyoffers.netzero.net/TGL3241/54bd90f12addb10f06697st03duc
Message 5
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| Subject: | Re: Power Generation without Battery? |
Use a lead acid battery? Something like a PC545 at 11.4 lb may be an
acceptable weight penalty?
Peter
On 19 Jan 2015 23:03, "Chris Mullins" <mullincl@gmail.com> wrote:
> Bob,
> I am building a Carbon Cub - a lightweight experimental design for
> backcountry use. It will use a fully electrically dependent Lycoming
> engine. I plan on 1 battery/2 alternators, and I desire the system to run
> the engine with any 1 of those 3 failed.
>
> I want to use a lithium battery for starting purposes only. I am not
> worried about battery only endurance with 2 other power sources.
>
> Alternator technology is mature, but Li batteries seem to be still
> evolving. Some type of battery fault would seem be a likely failure mode in
> my planned system. (I'd like to monitor battery temp using a probe and my
> on board electronics, and to have some way to electrically isolate or even
> physically remove the battery).
>
> I plan to use your Z12 or Z13 architecture.
>
> People I speak with advise me that alternators (even the SD8) are
> dependent on a functioning battery in the system, and that they will cease
> to function if the battery fails or is taken offline.
>
> Recent revelations regarding the Challenger/Aerovoltz scenario aside,
> there seem to still be legitimate issues with the current Li crop. At the
> very least they remain relatively unproven.
>
> So I am concerned about the Li battery being a single point of failure
> capable of stopping the engine.
>
> How can I design around this problem?
>
> Chris M
>
> *
>
>
> *
>
>
Message 6
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| Subject: | Re: Insulated ground cables? |
Here's a picture of the clamp. It clearly has the contact patch that Roger
described.
The fit is not at all tight.
It's cabled to the wing skin under a nacelle. The cable attaches to the
skin about 1.5" from the bulkhead fitting supporting the tube...
Thankfully, if the tube comes completely disconnected at each end from it's
fittings, it still has a path to ground...(kidding).
I still don't know the original intent, but the owner is satisfied that the
fuel lines are grounded. Mission accomplished.
Thanks for all the input,
--Dave
[image: Inline image 1]
Message 7
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| Subject: | Re: Power Generation without Battery? |
Chris,
If your mission profile could put you in the back country with ground support hundreds
of miles away, you may want to consider a few ideas:
1. Consider changing architecture to 2 batteries & 1 alternator. If your only
battery goes dead or has diminished capacity due to extreme cold, you done. Having
an extra alternator won't get the engine started.
2. Maybe this is not the place for un-proven lithium battery technology. Again,
if your survival depends on it, you may want to go w/ technology that has a
proven track record.
-Jeff
On Monday, January 19, 2015 3:51 PM, Peter Pengilly <peter@sportingaero.com> wrote:
Use a lead acid battery? Something like a PC545 at 11.4 lb may be an acceptable
weight penalty?
Peter
On 19 Jan 2015 23:03, "Chris Mullins" <mullincl@gmail.com> wrote:
Bob,
>I am building a Carbon Cub - a lightweight experimental design for backcountry
use. It will use a fully electrically dependent Lycoming engine. I plan on 1
battery/2 alternators, and I desire the system to run the engine with any 1 of
those 3 failed.
>
>I want to use a lithium battery for starting purposes only. I am not worried about
battery only endurance with 2 other power sources.
>
>Alternator technology is mature, but Li batteries seem to be still evolving. Some
type of battery fault would seem be a likely failure mode in my planned system.
(I'd like to monitor battery temp using a probe and my on board electronics,
and to have some way to electrically isolate or even physically remove the
battery).
>
>I plan to use your Z12 or Z13 architecture.
>
>People I speak with advise me that alternators (even the SD8) are dependent on
a functioning battery in the system, and that they will cease to function if
the battery fails or is taken offline.
>
>
>Recent revelations regarding the Challenger/Aerovoltz scenario aside, there seem
to still be legitimate issues with the current Li crop. At the very least they
remain relatively unproven.
>
>So I am concerned about the Li battery being a single point of failure capable
of stopping the engine.
>
>How can I design around this problem?
>
>
>Chris M
>
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