Today's Message Index:
----------------------
1. 04:50 AM - Z14 architecture (Krea Ellis)
2. 05:17 AM - Re: Changes in education field and technology (Verolla)
3. 06:04 AM - Seat heaters (Krea Ellis)
4. 07:28 AM - Re: Z14 architecture (Robert L. Nuckolls, III)
Message 1
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| Subject: | Z14 architecture |
The whole reason for the cross-feed contactor
is to PREVENT a 'dire emergency' . . . not
react to one.
I=99m not sure I follow this. I assumed the contactor is
installed for the possibility of alternator and battery failure on one
bus (or to tie the batteries together for engine start). I=99m not
sure exactly how this would happen, given crowbar protection for the
alternator, unless the battery was weak or the bus somehow was shorted?
If the bus was shorted, then closing the cross-tie would bring the other
side down too, I assume. A good preflight should discover a weak
battery. My concern would be bus failure, but after a little education
from you here, it sounds like properly installed busses and their wire
feeds generally don=99t fail. Point taken and lessen learned if
true.
Okay, failure of WHAT component would prompt closing
the cross-tie? Will failure of that component result
in instant loss of engine?
First question answered (maybe) above. As to the second question -
(assume you are referring to electrical components here) - failure of
the single power source injector bus. Again, starting to learn from you
- I=99m going to guess your response will be that it=99s not
a single power source and if well constructed, the chances of failure of
both the alternator AND battery OR the bus are extremely remote?
Batteries which, in my never humble opinion,
only add cost of ownership and offer little
benefit in terms of mission reliability.
If for nothing else, the IBBS battery keeps the screens from rebooting
during start - which I have seen numerous times on my RV-7 (single
battery). Maybe not necessary with dual bus architecture and dual
batteries cross-tied for engine start. Your thoughts?
Define 'slightly' and articulate the
sequence of failure events that would
bring that benefit into play.
Lacking a batter explanation, I would say my preference would be to have
the ability to power an injector bus from either main/hot battery bus.
That would be my idea of slightly more redundant. If it is possible to
do so without introducing additional components that either (a) add
failure points that don=99t justify their existence and (b)
don=99t require test pilot type skills for intervention then that
would be a great achievement. All of this exercise has happened to
satisfy my concern of the loss of power to the injector bus. I=99m
not well versed enough to articulate what failures might occur to
require the second power source.
I suggest that what we're doing here
has the same goals. Another goal is to
eliminate the word 'emergency' from the
lexicon of electrics-speak . . . we're
just not going to have one.
And I am very grateful to have you and the others on this forum as a
resource to help me through this fun (and sometimes trying) process.
I=99m not the only one doing this right now and I think we will
all benefit from the review and your experience.
Krea Ellis
Message 2
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| Subject: | Re: Changes in education field and technology |
Modern students have a lot of opportunities to have excellent grades without making much effort. Of course I'm talking about professional writing services (https://www.paperwritingpro.com/) and I admit that I also use the help of paper writers. This is normal if the student doesn't have enough time or knowledge to write an essay. No one wants to get bad grades.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=494613#494613
Message 3
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I installed these in my RV6. The '2 seats with 5Lv' model will give you
what you're looking for.
https://www.ebay.com/itm/Car-Seat-Heater-Kit-Carbon-Fiber-Universal-Heated
-Cushion-Warmer-2-level-5-level/253250702661?ssPageName=STRK%3AMEBIDX%3A
IT&_trksid=p2057872.m2749.l2649
<https://www.ebay.com/itm/Car-Seat-Heater-Kit-Carbon-Fiber-Universal-Heate
d-Cushion-Warmer-2-level-5-level/253250702661?ssPageName=STRK%3AMEBIDX%3
AIT&_trksid=p2057872.m2749.l2649>
Hope that helps,
Charlie
Thanks, Charlie! I will look into those.
Message 4
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| Subject: | Re: Z14 architecture |
At 06:48 AM 2/3/2020, you wrote:
>The whole reason for the cross-feed contactor
>is to PREVENT a 'dire emergency' . . . not
>react to one.
>
>I'm not sure I follow this. I assumed the contactor is installed
>for the possibility
> of alternator and battery failure on one bus . . .
Alternator failure only . . . you wouldn't
know if a battery 'failed' in flight and besides,
properly maintained batteries don't fail . . .
they get replaced at some significant point
on their wear-out curve.
> (or to tie the batteries together for engine start).
True. This was one of the disappointments
in Garmin's 'adaptation' of Z-14 in
their installation manual. They replaced
the cross-feed contactor with a diode.
this PREVENTED exploitation of BOTH
batteries to crank a 6-cyliner engine!
> I'm not sure exactly how this would happen, given crowbar protection for the
>alternator, unless the battery was weak
Substitute 'neglected' for 'weak'
>or the bus somehow was shorted?
Okay . . . pick any airplane. Any
suite of tools . . . then go in and
'short' any distribution component
to ground. How would you do it? How
would that same even occur spontaneously
in an artfully assembled airplane?
Answer is, they don't. In 45 years of
herding electrons and chasing failure
gremlins in a/c . . . I've never encountered
a 'shorted' anything when it comes to
power distribution hardware. Plenty
of opens, burned up, cracked or simply
crapped out . . . but no faults to
ground precipitating broad, multi-system
failures.
I've not read any accident analysis where
shorted bus distribution hardware initiated
or contributed to a bad day in the
cockpit.
>If the bus was shorted, then closing the cross-tie would bring the other
>side down too . . .
Moot point per assertions above . .
>I assume. A good preflight should discover a weak battery.
No assumptions warranted . . . good
preventative maintenance replaces
a battery before it becomes un-airworthy.
> My concern would be bus failure, but after a little education
> from you here,
>it sounds like properly installed busses and their wire feeds
>generally don't fail.
>Point taken and lessen learned if true.
Correct. There are things like
wing struts, prop bolts, propeller blades,
control cables, elevator hinges, etc. etc.
that are simply not part of the design
decisions and operating (plan-b) considerations
for electrical systems. While there are
stories of such failures they are so rare
that any such event is really big news.
. . . and when you do hear of such things,
there are seldom details on the chain
of events that lead up to the ultimate
failure.
>Okay, failure of WHAT component would prompt closing
>the cross-tie? Will failure of that component result
>in instant loss of engine?
>
>First question answered (maybe) above. As to the second question -
> (assume you are referring to electrical components here) -
Yes
>. . . failure of the single power source injector bus. Again,
>starting to learn from you
>- I'm going to guess your response will be that it's not a single power source
>and if well constructed, the chances of failure of both the alternator AND
>battery OR the bus are extremely remote?
Exactly!
>Batteries which, in my never humble opinion,
>only add cost of ownership and offer little
>benefit in terms of mission reliability.
>
>If for nothing else, the IBBS battery keeps the screens from rebooting
>during start - which I have seen numerous times on my RV-7 (single battery).
>Maybe not necessary with dual bus architecture and dual batteries cross-tied
>for engine start. Your thoughts?
varies from system to system, a/c to
a/c . . . and we have discussed ways
to fabricate an electrical system
that negates brown-out effects without
adding (ugh!) more batteries.
>Define 'slightly' and articulate the
>sequence of failure events that would
>bring that benefit into play.
>
>Lacking a batter explanation, I would say my preference would be to have the
>ability to power an injector bus from either main/hot battery bus. That would
>be my idea of slightly more redundant.
Z-14 as published already does that,
from either the main or aux busses.
Z-12 has a similar degree of robustness
with a single bus.
I'm not well versed enough to articulate what failures might occur to
require the second power source.
. . . which is a perfectly legitimate
cause for concern. Ignorance is at
least crippling if not dangerous.
Education is neither easy or cheap.
We all have to work at it.
>I suggest that what we're doing here
>has the same goals. Another goal is to
>eliminate the word 'emergency' from the
>lexicon of electrics-speak . . . we're
>just not going to have one.
>
>And I am very grateful to have you and the others on this forum
>as a resource to help me through this fun (and sometimes trying) process.
That's what we do here . . . and
we're pleased that you're finding
value in what is offered.
Bob . . .
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