Today's Message Index:
----------------------
1. 12:13 PM - Re: Grounding a Super Cub (Peter Pengilly)
2. 01:26 PM - (Bill Settle)
3. 05:03 PM - Re: (Robert L. Nuckolls, III)
4. 06:20 PM - Re: Grounding a Super Cub (Tundra10)
5. 06:41 PM - Re: Re: Grounding a Super Cub (Bill Bradburry)
Message 1
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| Subject: | Re: Grounding a Super Cub |
Not trying to cause any trouble here!!!
My airplane is a single seat aerobatic One Design - I was very keen to
keep weight to a minimum, and I wasn't too concerned about the compass
(definitely VFR only). To ensure good starting I decided to 'spend' 2lb
on a Sky-tec NL starter - which draws much less current than a permanent
magnet type (also achieves better engagement on starter ring, but that
may have been a peculiarity of my engine). With a PC680, starter
solenoid on top of battery and once length of wire from solenoid to
starter so far starting has been good, even in damp, cold weather after
several weeks of inactivity. I could have gone with Eric's copper
covered aluminium wire, but I had the copper wire to hand ... If I was
going to use heavy gauge both ways I would definitely use his Super-CCA
wire.
Thinking about it I guess my design goals might not be that similar to a
Tundra or Super Cub builder!
Peter
On 30/01/2013 05:17, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
>
>> I have tube & fabric aircraft with an IO-360 and the battery in the
>> back. I have a tab welded on on the engine mount and a tab welded on
>> the frame near to the battery both used for earth strap connection.
>> What is the down side of putting very short duration starter current
>> through the engine mount, and equally through the fuselage frame?
>
> They're magnetic materials . . . steel . . .
> with higher resistance than copper. While
> carrying high currents, the steel conductors generate
> strong local magnetic fields which do not go
> completely away after the current goes to zero.
>
> Remote battery grounding on aluminum airplanes is
> less problematic . . . but many builders still run
> starter currents through the engine mount and/or
> fire wall sheet . . . for the most part they don't
> perceive any problems. Performance degradation is
> most likely to present during cold weather cranking.
>
> So MANY things pile on top of each other in cold
> weather that one is unlikely to see much difference
> fore wired vs. airframe battery ground. But a combination of
> design and preventative maintenance efforts can
> add up to a significant difference. Those would
> include selection of starter, keeping the battery
> well maintained, minimizing joints in the cranking
> path, and in extreme conditions, warming the engine
> and battery, etc.
>
>> Why would the (very thin) firewall be any better?
>
> It's not. I try NEVER to depend on fire wall sheet for anything
> other than grounding of light draw accessories like case-ground
> regulators, facet fuel pumps, starter contactors, etc.
>
>> Most people I know have saved the weight of a 2nd heavy gauge wire
>> by using the fuselage frame as the ground return.
>
> Which is what's been done on thousands of airplanes
> for 100+ years . . . but I'm aware of no study
> that quantifies performance or maintenance issues
> for having done so.
>
> My personal design goals call for a minimum number
> of made up joints between battery (-) and crankcase
> and avoid using airframe ground for all but the few
> outlying appliances depicted in Figure Z-15. The ideal
> battery ground is an engine-cranking-sized-wire from
> battery(-) to fire wall single-point ground . . . and
> a second conductor from single-point ground stud
> to the crankcase.
>
> But if one wishes to embrace another philosophy,
> it will probably function.
>
>
> Bob . . .
>
>
Message 2
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Bob,=0A =0AI'm trying to figure out my LED Nav lights and I have a couple o
f questions: I =0Abought a set of wingtip LED Nav lights from a builder of
f of VAF who was =0Aproducing them prior to you offering your LuxDrive filt
ers. They came with =0A700mA LuxDrive Power Pucks. After you started offe
ring your filters, I bought a =0Acouple of those. They came with 1000mA Po
wer Pucks. Can I use the 1000mA =0Amodels or should I reorder 700mA units?
=0A=0A =0AWhen I received the filters, it came with a hand written sketch
for a wiring =0Adiagram. I have since downloaded a newer schematic from y
our website. =0AComparing the two, I see there is a difference in them con
cerning pins 2 & 3. =0AOn the original hand written one, both pins are lab
eled =9CN/C=9D. I assume this =0Ameans =9CNot Connected.
=9D (?) The newer schematic shows pin 2 as 5v ref and pin 3 =0Aas
=9CControl Dimming.=9D As I am not considering dimming my Nav
lights, I don=99t =0Aneed to connect these, correct?=0A =0AAlso, on b
oth drawings, pins 4 & 8 and pins 5 & 9 are common with each other. =0AIs
this for one filter to drive two different Nav lights?=0A=0AThanks,=0ABill
Settle=0ARV-8
Message 3
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At 03:24 PM 1/30/2013, you wrote:
>Bob,
>
>
>I'm trying to figure out my LED Nav lights and I
>have a couple of questions: I bought a set of
>wingtip LED Nav lights from a builder off of VAF
>who was producing them prior to you offering
>your LuxDrive filters. They came with 700mA
>LuxDrive Power Pucks. After you started
>offering your filters, I bought a couple of
>those. They came with 1000mA Power Pucks.
Were you wanting filter boards only for your 700mA
devices? Are they the 3021 series devices with
ECB pins?
http://tinyurl.com/a4nltlv
If so, you can trade your 1000 mA filtered supplies
for filters + refund.
> Can I use the 1000mA models or should I reorder 700mA units?
As shown on the LuxDrive data sheet, you can
'dim' the 3021 series devices by connecting
the appropriate resistor between CTRL and REF
pins.
Emacs!
This adjustment sets a new operating current
that is lower than the rated current for the
device.
>
>
>When I received the filters, it came with a hand
>written sketch for a wiring diagram. I have
>since downloaded a newer schematic from your
>website. Comparing the two, I see there is a
>difference in them concerning pins 2 & 3. On
>the original hand written one, both pins are
>labeled =9CN/C=9D. I assume this means =9CNot
>Connected.=9D (?) The newer schematic shows
>pin 2 as 5v ref and pin 3 as =9CControl
>Dimming.=9D As I am not considering dimming my
>Nav lights, I don=99t need to connect these, correct?
You can wire a resistor (about 220 ohms I think)
between 2 and 3 on the 9-pin connector to set
your 1000 mA units to any desired lower current.
I now offer bench adjusted power supplies wherein
I attach a resistor to the bottom of the board that
produces the desired maximum current . . . this lets
me stock only one power supply (1000 mA) to service
the full range of builder needs.
In the future, I'll be re-laying the board to provide
a clearance hole to the potentiometer that comes
on the "I" devices.
>Also, on both drawings, pins 4 & 8 and pins 5 &
>9 are common with each other. Is this for one
>filter to drive two different Nav lights?
If your lamps are two strings of leds in
series where each requires 1/2 of total current,
then the extra pins enable that connection.
Let me know what works for you.
Bob . . .
Message 4
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| Subject: | Re: Grounding a Super Cub |
My friend has some 2AWG available from another project, so he will be using that.
However, I tried to do a comparison between 2AWG and 4AWG, based on Bob's discussions
of voltage at the starter motor.
It seems that battery internal resistance and connection resistance are the most
significant factors.
I calculated that for his airplane it will cost 2.2 additional pounds to gain 4%
more voltage at the starter. For my airplane, with the battery on the firewall,
it would cost 0.8 pounds to gain 1.5% more voltage at the starter.
I think longer cable runs are required before the lower resistance cable makes
a significant difference.
A battery with lower internal resistance makes the biggest difference of all.
Jeff Page
Dream Aircraft Tundra #10
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=393334#393334
Message 5
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| Subject: | Re: Grounding a Super Cub |
Tell him to try some of this lightweight wire.
http://www.periheliondesign.com/fatwires.htm
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Tundra10
Sent: Wednesday, January 30, 2013 9:19 PM
Subject: AeroElectric-List: Re: Grounding a Super Cub
My friend has some 2AWG available from another project, so he will be using
that.
However, I tried to do a comparison between 2AWG and 4AWG, based on Bob's
discussions of voltage at the starter motor.
It seems that battery internal resistance and connection resistance are the
most significant factors.
I calculated that for his airplane it will cost 2.2 additional pounds to
gain 4% more voltage at the starter. For my airplane, with the battery on
the firewall, it would cost 0.8 pounds to gain 1.5% more voltage at the
starter.
I think longer cable runs are required before the lower resistance cable
makes a significant difference.
A battery with lower internal resistance makes the biggest difference of
all.
Jeff Page
Dream Aircraft Tundra #10
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=393334#393334
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