Today's Message Index:
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0. 12:12 AM - Just A Few Days Left; Well Behind Last Year... (Matt Dralle)
1. 06:07 AM - Re: SD8 alt connection (gonzo24)
2. 01:05 PM - Re: Re: SD8 alt connection (Robert L. Nuckolls, III)
3. 01:09 PM - Re: Re: Z-13/8 Rev. R (Robert L. Nuckolls, III)
4. 01:16 PM - Re: Re: Z-13/8 Rev. R (Robert L. Nuckolls, III)
5. 04:08 PM - Re: Z13/8 Rev Q comments (Robert L. Nuckolls, III)
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Subject: | Just A Few Days Left; Well Behind Last Year... |
Dear Listers,
There are just a few more days left of this year's List Fund Raiser. Response
has been good so far, but we're well behind last year at this point. If you've
been waiting until the last minute to make your Contribution, now might be good
time to show your support and maybe pick up a nice gift as well!
Please remember that there is no commercial advertising on these Lists and the
*only* means of keeping them running is through your Contributions during this
Fund Raiser. If it weren't for your individual Contributions, these Lists could
easily become economically infeasible and simply cease to exist.
You probably can't even take the family out to dinner for $20 these days, but your
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Please make a Contribution today with a Credit Card or Paypal:
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Or, drop a personal check in the mail to:
Matt Dralle / Matronics
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Thank you!
Matt Dralle
Matronics Email List Administrator
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Subject: | Re: SD8 alt connection |
Bob,
thank you for the reply. In reviewing the Z-13/8 schematic... since the 2awg batt
and 14awg batt buss are all connecting at the same point on the batt contactor
on the engine side of the firewall.... Wouldn't it be the same thing to
terminate the SD-8 output lead directly to the battery buss stud inside the cabin?
I ask this as all of my SD-8 power components i.e. regulator, capacitor, OV, relay
are installed cabin side of the firewall (per the instructions received with
these parts). Why would it be necessary to run the lead with the inline 30amp
fuse back out to the batt contactor? In the event of a Primary alt failure,
the SD-8 should still be excited through the 14AWG contact it has to the primary
battery.
Should one connect a smaller aux batt on the Batt buss as well in this case? I
ask this as LSE's power diagram shows two batteris for dual ignition as well.
thank you for your time.
--------
RV-7a completed flown 700+ hrs sold
Rv-7 under construction
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=320077#320077
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Subject: | Re: SD8 alt connection |
At 08:03 AM 11/19/2010, you wrote:
>
>Bob,
>
>thank you for the reply. In reviewing the Z-13/8 schematic... since
>the 2awg batt and 14awg batt buss are all connecting at the same
>point on the batt contactor on the engine side of the
>firewall.... Wouldn't it be the same thing to terminate the SD-8
>output lead directly to the battery buss stud inside the cabin?
Whoops! You have an always hot fat wire coming through
the firewall?
>I ask this as all of my SD-8 power components i.e. regulator,
>capacitor, OV, relay are installed cabin side of the firewall (per
>the instructions received with these parts). Why would it be
>necessary to run the lead with the inline 30amp fuse back out to the
>batt contactor? In the event of a Primary alt failure, the SD-8
>should still be excited through the 14AWG contact it has to the
>primary battery.
Okay, you've arranged components with priorities ordered
differently than suggested in the Z-figures and I understand
why. I wish B&C wouldn't put those little notes in with
his products suggesting that certain electro-whizzies are better
off inside the cabin.
Sure, connect the SD-8 to the battery bus . . . in fact,
put a 30A fuse in one of the battery bus fuse-slots and
use it to route power to the system.
Airplane parts are airplane parts. They are selected and
qualified for specific duty in locations selected first
for functionality, minimum parts count, weight, and nice
failure mode effects analysis. Obviously, boxes with LCD
displays, push buttons and knobs NEED to go in the cabin
and their tolerance for environmental extremes are relaxed
because shares spaces where people sit. All other gizmos,
particularly system power management parts should be happy
living anywhere except perhaps bolted to an exhaust stack.
The current locations for your SD-8 system parts
and battery bus are now pretty much a given so you're
compelled to make adjustments for how the wires are
handled.
>Should one connect a smaller aux batt on the Batt buss as well in
>this case? I ask this as LSE's power diagram shows two batteris for
>dual ignition as well.
No . . . don't mix-match architectures. I've
encountered several instances where the system
integrator attempted to cherry-pick what appeared
to be "good and wonderful" features of multiple
systems with the notion that each plucking of
an idea makes the whole more righteous.
The whole idea behind LSE's recommendations go
to increasing probability that at least one
of two ignition systems will have power irrespective
of MULTIPLE failures . . . and without regard to
the thought processes that ago toward fabrication
of a FAILURE TOLERANT system.
The battery in the OBAM aircraft owned, operated
and maintained by a cognizant builder is the most
reliable source of energy in the airplane. It's
only limitation is total stored energy traded off
with how much lead, water and plastic the builder
is willing to drag around. Then comes TWO, engine
driven power sources capable of mitigating battery
limitations. By the way, if you DO find yourself
operating either battery only . . . or battery+SD8,
then turn one of the ignition systems off. The
engine will hardly know the difference and your
electrical system loads drop by about 2 amps.
B&C and LSE make recommendations based on their
best wishes and understanding of the systems they
sell. The AeroElecric Connection goes toward a
rational approach for crafting the whole system
based on ingredients that go into recipes for
success going WWWwaaayyyy back . . . further
than any current supplier of electro-whizzies.
Understand that supplier recommendations are
almost never 'wrong'. But most suppliers are
not system integrators with a focus on the big
picture. Note how many different Z-figures there
are as opposed to how many ways the legacy T/C
aircraft is wired . . .
I'll have a first-hand review of a dark-n-stormy
night story to share with the List where the
outcome wasn't a complete disaster . . . everybody
walked away. The system integrator cherry-picked
whippy ideas without regard their 'fit' in the
overall system. The effects of some poor decisions
were expensive and linger to this day. I'll tell
you all about it after the court case settles.
Please don't take anything above as a
harbinger of doom for what you've described.
Your system's WIRING and FUNCTIONALITY are
going to be just fine and will function as
advertised. We're only sifting through the
simple-ideas that go to very low orders of
risk.
>thank you for your time.
You're most welcome. That's what we're all here
for . . .
Bob . . .
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Subject: | Re: Z-13/8 Rev. R |
At 02:26 PM 11/18/2010, you wrote:
>
>Bob,
>I was under the impression that EMAG Air had discontinued the "E"
>mag and was only making/selling the "P" mag. Just thinking that if
>you're revising it, maybe worthwhile to look into that also.
Interesting. Thanks for the heads-up. I note that the
e-models are not priced on the website. I've not talked
with those guys for awhile, I need to give them a call
and catch up.
Bob . . .
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Subject: | Re: Z-13/8 Rev. R |
At 11:46 AM 11/18/2010, you wrote:
>Minor comments to consider:
>
>My local experience is that most everyone building these days, even
>those on a budget, are installing engine monitors. Stand-alone low
>voltage monitors are not required. Similarly, alternator load
>meters and their associated shunts have been replaced by Hall effect
>sensors and the engine monitor. Maybe its time to modernize the
>schematic to reflect this? Just a thought...
The Z-figures are not a "do it this way" document.
They're an example of an ARCHITECTURE which speaks
to failure tolerance for a particular combination
of flight-profile-driven battery and alternator
decisions.
Whether or not a particular airplane is fitted with
the accessories illustrated is not germane to the
intent and purpose of the Z-figure. There's an endless
combination of accessories that may drive sizes of
busses, sizes of battery, size of alternator, sizes
of wires, choices of ignition systems and yes . . .
methodology for monitoring any of the ship's functions.
The most important thing to consider for LV monitoring
is timely, unambiguous and attention getting notification
for "time to switch to plan-b". If the builder has some
alternative means for accomplishing that, great. The
reason for having it in the Z-figure is to simply remind
the planner that SOME form of device needs to be a
part of the final recipe for success.
Bob . . .
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Subject: | Re: Z13/8 Rev Q comments |
At 12:15 AM 11/19/2010, you wrote:
>
>Bob,
>
>I wonder why the feed paths to the Endurance Bus are different. The
>relay from the battery bus is 14 awg and fused, while the diode from
>the main power bus is 16 awg and not fused.
Good question. The 16AWG wires are adequate to the
current carrying task assigned to power the e-bus
and you'll note that they're called out as "short"
wires. As "short", potentially sacrificial wires,
we'd like them to fuse open as fast as practical,
hence make them as small as practical. As we discovered
in this experiment on the bench some time back . . .
http://aeroelectric.com/Pictures/Wire/22AWG_20A.pdf
. . . a 20 AMP current through a 22AWG wire didn't
warm it enough to put the 150C insulation at risk.
So we could probably wire the short normal feed path
with 20 or even 18 AWG without 'over stressing' the
the wire.
An e-bus configured to the original idea calls for
punching through a cloud layer at the home airport,
failing an alternator, and flying comfortably to
airport of intended destination battery only. This
called for getting alternator-out endurance-bus loads
down to 2 or 3 amps. Not an terribly difficult task in
the magneto/steam-gage era.
Then came electrically dependent engines and
clusters of panel mounted 'stuff' that increased
the size of a 'minimalist' power requirement.
Okay, add the SD-8 and we've got 8-10 amps of
continuous load without depleting the battery.
Figure 2-3 amps of the original concept on top
of that and one COULD consider an e-bus load of
perhaps 13 amps. Okay, the feeders had to take
a big jump in AWG. Hence the fat feeder
for alternate feed path. If we're to observe
the reverence for crash safety and limit always
hot feeders to 7A or less, then the S704 relay
gets added and the fuse sizes go up to accommodate
the new definition of endurance loads.
This illustrates the thinking behind the disparity
between normal and alternate feed wire sizes.
>Previously, I was planning to use 14 awg and * 6 inches or less wire,
>without any fuses for both paths.
How did you arrive at this? When the battery and main
bus fuse blocks are immediately adjacent to each other,
then the no-fuse, 16AWG feeders (or even smaller
as described above) through the diode fits legacy
design goals. But the feeder from the battery
bus to the e-bus is a long conductor that classically
gets either:
(1) 7A or less protection for skinny feeder and no
remote mini-contactor or
(2) a larger feeder and contactor per Z-32. The larger
14AWG wire is appropriate for low voltage drop on longer
wires good for up to 15A and rear mounted batteries. If
your battery is up front, that wire could comfortably
drop to 12AWG.
>I have changed my drawing so both paths include fuses.
Doen't hurt . . . but not necessary by legacy design
goals.
>Since Z13/8 highlights some new technology with E-Mags, perhaps it
>makes sense to replace the Ford regulator with an electronic one that
>includes overvoltage protection and low voltage annunication ?
As suggested in an earlier post, you are encouraged
to consider the full constellation of available accessories
to put frosting on the Z-13/8 cake. I doubt that no two
OBAM airplanes flying this ARCHITECTURE have the same
frosting. It's my personal goal to suggest the simplest,
lowest cost suite of components that get the job done.
If the builder's design goals and pocket-book goes beyond
those suggestions, great!
Bob . . .
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