Today's Message Index:
----------------------
1. 02:09 AM - Re: Toroid beads (D L Josephson)
2. 04:08 AM - Re: Toroid Beads (Gautier, Thomas N (3266))
3. 06:04 AM - Jeff's aircraft electrical schematic (user9253)
4. 06:04 AM - was RV- 14, now electrical redundancy (GLEN MATEJCEK)
5. 07:24 AM - Re: was RV- 14, now electrical redundancy (Kelly McMullen)
6. 08:21 AM - Re: Re: Toroid beads (Robert L. Nuckolls, III)
7. 08:32 AM - Re: was RV-14, now brownouts/resets at engine crank (Dj Merrill)
8. 08:49 AM - Re: was RV- 14, now electrical redundancy (Robert L. Nuckolls, III)
9. 09:09 AM - Re: Jeff's aircraft electrical schematic (Jeff Luckey)
10. 09:56 AM - Re: was RV- 14, now electrical redundancy (Ralph Finch)
11. 10:40 AM - Re: was RV- 14, now electrical redundancy (Robert L. Nuckolls, III)
12. 11:42 AM - Re: was RV- 14, now electrical redundancy (Jeff Luckey)
13. 02:49 PM - Re: was RV- 14, now electrical redundancy (Justin Jones)
14. 04:37 PM - Re: was RV- 14, now electrical redundancy (Ralph Finch)
15. 05:45 PM - Re: Re: Wiring RV7 with Z13 diagram (2 alternators, 1 battery) (Justin Jones)
16. 10:19 PM - brown out on start (peter goudinoff)
Message 1
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| Subject: | Re: Toroid beads |
I agree with Bob that ferrite donuts are not necessary or desirable for
VOR/LOC/GS antennas. If you want good symmetrical coverage, you want a
balanced feed for your dipole and the folded balun shown in Bob's
http://tinyurl.com/yytxwd3
is a good way to do that. The benefits are observable in the cockpit in
the form of increased reception range for weak signals.
If you want to make a com antenna and it's tuned correctly but you want
it to be a little more broadband (lower VSWR at the band edges,) using a
string of ferrite toroids or a tubular ferrite core is one approach.
You are using the ferrites to create loss, not coupling. In effect you
create a high resistance for currents flowing on the outside of the
shield. It is partly resistance, not just impedance. If there is high
VSWR, the ferrite heats up when you transmit, the same as a resistor in
series would, allowing some of the reflected power to be dissipated as
heat rather than bouncing back to the radio. This is not *exactly* what
you want, but it's better than having the radio shut down if you try to
transmit at 135 MHz and your antenna is sharply tuned to 122.
You do not want to create additional tuned circuits by looping the coax
through one larger toroid, you just want to create resistive loss for
reflected power, because you haven't designed an antenna that's
inherently broadband enough (good broadband antennas don't need
ferrites.) A suitable sleeve or tube core is Fair-Rite 2643625202,
available from Mouser
http://www.mouser.com/ProductDetail/Fair-Rite/2643625202 for about a
dollar. This can substitute for the 3 or 4 donuts often used. You should
use ferrites only when you can't get the VSWR low enough any other way.
--
David Josephson
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| Subject: | Re: Toroid Beads |
If you decide to go the bead route check out
palomar-engineers.com
for a source of suppressor beads for coax. They have a nice application chart.
Nick Gautier
Sent from my iPhone
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| Subject: | Jeff's aircraft electrical schematic |
Jeff attached this schematic to the RV-14 thread.
http://forums.matronics.com/download.php?id=39981
Jeff, has this architecture been used in a flying aircraft yet?
I like it and think that it deserves peer review.
I think that the 60 amp alternator fuse and 100 amp battery current limiter are
redundant. An alternator is self current limiting. An alternator fuse protects
the battery and wires, not the alternator. So I suggest that the 100 amp
battery fuse be replaced by a 60 amp fuse, and eliminate the 60 amp fuse in the
alternator circuit.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=432247#432247
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| Subject: | was RV- 14, now electrical redundancy |
>
> Peter and Jeff-
>
I wrestled with the same issues, and although I've not yet flown my night /
ifr capable RV yet, I like what I've come up with. The short version is
that I've a primary efis w/ engine instruments and a backup efis six pack.
Given that cranking and avoiding brown out pretty well required two
batteries, I ultimately adopted Bob's two identical battery, swap one out
per year concept. The starter, main alternator, main bus (including the
switched stby efis), and main battery comprise one branch of my system.
The essential battery (Sorry folks; I'm not interested in any semantic
arguments... call it a kumquat if you like!) carries the essential bus,
which powers the primary efis un-switched and is supported by an SD-8 on
the vacuum pad. The two batteries are tied together with a Schotkey diode,
and the SD-8 regulator is set between battery and main alternator voltage.
Operation is dirt simple. Starting with the main alt off tests the stby.
In flight, the main alt carries the whole electrical system. Should the
main alt fail, the main bus is carried by the main battery and the SD-8
picks up the essential bus with precisely zero switch flipping by the
pilot. The efis will annunciate the drop in main bus voltage. Load
shedding at one's leisure will prolong the life of the main bus, but the
SD-8 will ensure all the most important goodies have power for probably two
hours after the prop stops windmilling, even with battery contactors on
line.
I use fuses, with the only breakers on power sources. Failure of ANY one
component can't hurt me. YMMV, but I like it, a lot.
Message 5
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| Subject: | Re: was RV- 14, now electrical redundancy |
This discussion, as good as it is, has focused on hardware installed and
its capabilities, not mission "need".
Need varies from a military requirement to complete the mission
regardless of circumstances to if something fails I will land at nearest
suitable airport and deal with it. Night IFR by itself only has certain
minimum requirements, and if you "assume" that your missions will keep
you within XX minutes of a suitable airport, your needs are different
than if you assume you will need to fly to destination and thus need
electron capacity equal to the aircraft fuel range. Having electron
capacity greater than fuel range just adds unnecessary wt.
Then there is the consideration of how much effort the backups need to
allow pilot with minimum effort to safely reach his pre-determined goal.
I like the system described below, IF you assume your mission is over
hostile terrain, at night in IFR and need to go a considerable distance
to a suitable landing spot after a failure. Most of us don't really have
that mission requirement, but may want the capability.
Personally, having managed to escape a night time partial panel episode
in a non-radar mountainous region will no longer consider combining
night, IFR and mountains on the same flight in a single engine normally
aspirated aircraft. My preference would be to limit risk to one of those
challenges, but will consider a flight that combines two of them.
However, I really don't want mountains at night in anything with only
one engine and no turbo regardless of VFR or IFR. I already have enough
experience there to not want to do it again.
That is why I consider suitable IFR backup to be enough electrons to
function for 1 hour, maybe 1+30 to be adequate, and easily achievable
with batteries only backup rather than a second alternator. Each builder
will have to assess their mission goals and risk tolerance to decide how
much redundancy they need and how much they want. How much complexity
that does or does not add is a minor factor in the equation. I believe
Bob has always pushed us to most carefully evaluate what our goals and
mission needs were to decide on what architecture is appropriate.
On 10/25/2014 6:03 AM, GLEN MATEJCEK wrote:
>
> Peter and Jeff-
>
>
> I wrestled with the same issues, and although I've not yet flown my
> night / ifr capable RV yet, I like what I've come up with. The short
> version is that I've a primary efis w/ engine instruments and a backup
> efis six pack. Given that cranking and avoiding brown out pretty well
> required two batteries, I ultimately adopted Bob's two identical
> battery, swap one out per year concept. The starter, main alternator,
> main bus (including the switched stby efis), and main battery comprise
> one branch of my system. The essential battery (Sorry folks; I'm
> not interested in any semantic arguments... call it a kumquat if you
> like!) carries the essential bus, which powers the primary efis
> un-switched and is supported by an SD-8 on the vacuum pad. The two
> batteries are tied together with a Schotkey diode, and the SD-8
> regulator is set between battery and main alternator voltage.
>
> Operation is dirt simple. Starting with the main alt off tests the
> stby. In flight, the main alt carries the whole electrical system.
> Should the main alt fail, the main bus is carried by the main battery
> and the SD-8 picks up the essential bus with precisely zero switch
> flipping by the pilot. The efis will annunciate the drop in main bus
> voltage. Load shedding at one's leisure will prolong the life of the
> main bus, but the SD-8 will ensure all the most important goodies have
> power for probably two hours after the prop stops windmilling, even
> with battery contactors on line.
>
> I use fuses, with the only breakers on power sources. Failure of ANY
> one component can't hurt me. YMMV, but I like it, a lot.
>
> *
>
>
> *
Message 6
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| Subject: | Re: Toroid beads |
>You do not want to create additional tuned circuits by looping the
>coax through one larger toroid, you just want to create resistive
>loss for reflected power, because you haven't designed an antenna
>that's inherently broadband enough (good broadband antennas don't
>need ferrites.)
Agreed to within one important point. There are 'ferrites'
and then there are 'FERRITES' . . .
There's a constellation of mixes of metal and binders used
to fabricate the device. A ferrite core can be an
efficient, compact solution to the fabrication of an
inductor or transformer. In this instance, the manufacturer
strives for the LOWEST possible losses in the core material
at the frequency of interest.
When used as a mitigator of noise, design goals can include
a 'filter' comprised of combinations of inductors and capacitors
that provide high series impedance (inductor) and low shunt
impedance (capacitor) at the antagonistic frequencies. In this
case, low loss components don't 'exterminate' the noise, they
just 'contain' it.
With the advances in powered metal technologies it was
discovered that while putting a ferrite 'bead' or toroid
over a wire would create a lumped inductance of some small
value . . . the designer could, if goals warranted, include
some material in the bead that made it a lousy candidate for
tuned circuits or transformers. This material deliberately
created energy losses within the core material . . . losses
that converts antagonistic energies into heat thus reducing
their nuisance factors.
http://tinyurl.com/3b7nuj
As a general rule, ALL products sold for the purposes
of reducing noise will be fabricated from materials having
deliberate losses . . . like the filter 'beads' and
'snap around the cable' products.
But when you pick up one of those little donut shaped
thingies with no particularly defining features of
color or part numbers, you're in the dark. The
odd toroid captured in the wild is often optimized
for a rather narrow range of characteristics that
may or may not be suited to your task.
One of several resources for reviewing capabilities
and limits for the various products can be found
here . . .
http://tinyurl.com/nx4qb9h
In the case for the 'string of beads on the coax'
the goal is to de-couple currents flowing on the
feed line shield, the task is not to add a filtering
loss but to add a high-q (read low loss) common mode
inductance to the feed-line. This would become the
lumped component version of a Pawsey stub or Bazooka
balun.
As far as weak signal performance goes, the only
time you're even close to experiencing a 'weak signal'
event is trying to read a VOR radial that is WWAAAaaayy
off the beaten track for IFR operations.
When "flying the routes", your charts will be marked
with a VOR change-over point . . . a location along
a line between VOR stations that is "equal signal"
for the stations of interest. For this mode of flight ops,
signal strengths combined with modern receiver
capabilities make a 'weak signal' event due to
standing waves on your feed line a physical
impossibility.
I've played with 'beads on the coax' in the lab and
found their benefit to be difficult to measure with
boxes having names like Hewlett-Packard and Watkins-
Johnson on them. The notion that you're going to
get more meaningful measurements with a box having
Garmin or King on front is not grounded in practice.
A suitable sleeve or tube core is Fair-Rite 2643625202, available
from Mouser http://www.mouser.com/ProductDetail/Fair-Rite/2643625202
for about a dollar. This can substitute for the 3 or 4 donuts often
used. You should use ferrites only when you can't get the VSWR low
enough any other way.
Not very quantified . . . who actually measures VSWR
on a VOR antenna and what is 'low enough'? The measure
of antenna performance cannot be lumped into the VSWR
bucket. A resistor can have a VSWR of 1:1 over a huge
range of frequencies with ZERO performance while an
antenna with 'low enough' VSWR can perform poorly for
a variety of reasons not related to the antenna itself.
Antenna science is a BIG PICTURE activity that has
to included the entire sphere of interest . . . while
centered on your headphones, the sphere envelopes a host of
variables no single one of which is the holy grail
of satisfactory operations.
Consider some of the Blue Tooth, Wi-Fi and remote
control products. Very few of these devices have
antennas that would warm Bob Archer's heart . . . but
in the context of their operating sphere, they
perform as advertised. Some with pretty amazing
results. Dr. Dee can wear her little Blue-Tooth ear
piece and be out weeding in her garden while tutoring
a student. Amazes me.
Bob . . .
Message 7
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| Subject: | Re: was RV-14, now brownouts/resets at engine crank |
On 10/24/2014 11:41 PM, Robert L. Nuckolls, III wrote:
>
> Brownout resets are not an architecture problem,
> they're a radio problem. A radio that DOES NOT
> conform to DO-160 guidelines for graceful recovery
> after all manner of input power interruptions.
>
> That capability is supposed to be internal to
> the appliance, not external . . . and for good
> reason. What's the poor C-172 owner supposed to
> do when he wants to modernize his avionics but
> doesn't want to climb the Everest-of-paperwork
> necessary to modify the ship's certificated
> electrical system?
>
>
We've had this discussion on the list many times over the past few
years. We can spend days pointing fingers back and forth blaming the
manufacturer or whomever as to why the radio/efis/panel-goodie resets
when cranking the engine, but the simple reality is that we do have
equipment that resets, and going back to the manufacturer and pointing
at DO-160 likely isn't going to get us anywhere in the short term. One
could argue that continually pestering the manufacturer about the issue
might get us somewhere in the long term, but in the meantime we aren't
likely to return our $12,000+ EFIS system because of it, and we need to
move forward.
Comparing to a 172 owner isn't really relevant since we are
primarily talking about experimental avionics going into OBAM aircraft,
and they'll never see the inside of a 172 without highly unlikely and
significant regulatory changes. Again one could argue that regardless
of being experimental or not they should strive to meet some regulatory
specification, but again we are stuck with what we have and if we choose
to keep the equipment we need to factor it in, and move on, much like
when we got an airframe part in the kit that didn't fit just right and
we had to figure out how to make it work and continue building.
Fortunately for us in the OBAM community we aren't limited in that
manner, and are free to incorporate this into the design architecture.
With as many times as this has come up in recent years, it seems pretty
clear that brownout protection is a very desirable feature, and I'd go
so far as to say that it is a required feature for many posters given
the messages we've seen about it.
Yes, we could design a nice whiz-bang external band-aid device that
could be applied to each individual panel-goodie that resets, but as
soon as you have two of them in your panel you've now created
unnecessary complexity and increased component count. Many OBAM
aircraft today have at least two EFIS screens, and often three. Often
the manufacturers solution is to incorporate an internal battery into
each device, which does certainly work, but then leaves us with having
to maintain several batteries throughout the aircraft.
It would seem the more efficient means of addressing this is to
design it into the architecture from the start (pun intended), reducing
battery and parts count, and making the overall system as simple as
possible, and only as complex as it needs to be and no more.
In my humble opinion,
-Dj
--
Dj Merrill - N1JOV - VP EAA Chapter 87
Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Glastar Flyer N866RH - http://deej.net/glastar/
Message 8
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| Subject: | Re: was RV- 14, now electrical redundancy |
>
>That is why I consider suitable IFR backup to be enough electrons to
>function for 1 hour, maybe 1+30 to be adequate, and easily
>achievable with batteries only backup rather than a second alternator.
But why limit your horizon to 90 minutes if there's
simple, light, low cost of ownership combination of
hardware and planing that keeps the panel lit until
the engine runs out of fuel?
This is a mode of thinking not generally offered to
C-172 owners. I had a conversation with a company
pilot at Beech who had just delivered a new A-36
to a proud customer. He was extolling the virtues
of all the electro-whizzies on the panel to the
customer.
Later, I asked, "Did you check the guy out in flying
this airplane in the J-3 mode"?
"Say what? Why would I do that? He just paid a half
million for an airplane with air conditioning and the
kitchen sink . . . why would I even suggest that
he might want to acquire such skills about?"
Why indeed. The point is, I respectfully suggest that
there is no reason any OBAM aviation pilot should
experience an electrical 'emergency'. No single failure
should be cause to seek the nearest airport in boonies
because risks for continued flight to airport of
intended destination have driven up your pucker-factor.
> Each builder will have to assess their mission goals and risk
> tolerance . . .
Right ON! Let's not 'tolerate' risk, let's drive
it so close to zero that throwing a prop-bolt becomes
the more likely event to ruin your day.
Bob . . .
Message 9
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| Subject: | Re: Jeff's aircraft electrical schematic |
Joe,
I've been in discussions w/ several builders, both on this List and off, who asked
many questions and for permission to use this design. But as far as I know,
no one is flying it yet. My airplane is probably two years away from flying.
Re 60A fuse:
You are correct, the fuse is not to protect the alternator. It is to protect the
wire (the "B" lead) going to the alternator. If that wire were to go to ground,
we want that 60A to blow.
Without that fuse, the next fuse up the chain is the 100A "main" fuse and we don't
want a wire problem w/ the alternator B lead to kill the Battery A system.
BTW - I appreciate the ongoing analysis & scrutiny - makes us all smarter,
-Jeff
On Saturday, October 25, 2014 6:03 AM, user9253 <fransew@gmail.com> wrote:
Jeff attached this schematic to the RV-14 thread.
http://forums.matronics.com/download.php?id=39981
Jeff, has this architecture been used in a flying aircraft yet?
I like it and think that it deserves peer review.
I think that the 60 amp alternator fuse and 100 amp battery current limiter are
redundant. An alternator is self current limiting. An alternator fuse protects
the battery and wires, not the alternator. So I suggest that the 100 amp
battery fuse be replaced by a 60 amp fuse, and eliminate the 60 amp fuse in the
alternator circuit.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=432247#432247
Message 10
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| Subject: | Re: was RV- 14, now electrical redundancy |
On Sat, Oct 25, 2014 at 7:22 AM, Kelly McMullen <kellym@aviating.com> wrote:
> kellym@aviating.com>
>
> This discussion, as good as it is, has focused on hardware installed and
> its capabilities, not mission "need".
>
Not true. I speculated on the OP's mission: IFR as stated, possibly at
night, probably single-pilot, certainly single engine.
> Need varies from a military requirement to complete the mission regardless
> of circumstances to if something fails I will land at nearest suitable
> airport and deal with it. Night IFR by itself only has certain minimum
> requirements, and if you "assume" that your missions will keep you within
> XX minutes of a suitable airport,
An optimistic assumption...dangerous to make. Better to make pessimistic
assumptions.
> your needs are different than if you assume you will need to fly to
> destination and thus need electron capacity equal to the aircraft fuel
> range. *Having electron capacity greater than fuel range just adds
> unnecessary wt*.
>
No. Aircraft batteries add more weight than standby alternators and provide
much less endurance. At any rate, a bit of extra weight for an RV-14 is
hardly the critical factor.
> Then there is the consideration of how much effort the backups need to
> allow pilot with minimum effort to safely reach his pre-determined goal.
> I like the system described below, IF you assume your mission is over
> hostile terrain, at night in IFR and need to go a considerable distance to
> a suitable landing spot after a failure. Most of us don't really have that
> mission requirement, but may want the capability.
>
Most of the inter-mountain West (USA) would be considered hostile terrain
as is the Appalachian Range; we don't know where the OP lives, but at some
point he might cross them. Airports in the mountains are not close
together. And what if a nearby airport is under minimums and he needs to
travel a distance to reach an acceptable airport? He may not plan on night
IFR, but could easily find himself with a choice: late departure, arriving
at destination at night, OR stay overnight in Podunk Airport and leave in
the morning.
So plan for a system with at least, say, a 2- or 3-hour e-buss capacity.
But as Bob points out, it's easy--not more effort--to add indefinite
endurance, so why not do it?
I don't understand the notion that a 2nd alternator is greatly increased
complexity and effort, therefore all backup must be battery. Once you are
trapped in that thinking, poor trade-offs result.
Message 11
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| Subject: | Re: was RV- 14, now electrical redundancy |
>I don't understand the notion that a 2nd alternator is greatly
>increased complexity and effort, therefore all backup must be
>battery. Once you are trapped in that thinking, poor trade-offs result.
Precisely. "greatly increased" is non-quantified. To quote from
one of my heros . . .
"When you can measure what you are speaking about, and express it in
numbers, you know something about it; but when you cannot measure it,
when you cannot express it in numbers, your knowledge of it is of a
meager and unsatisfactory kind; it may be the beginning of knowledge,
but you have scarcely, in your thoughts, advanced it to the stage of science."
Sir William Thompson, Lord Kelvin (1824-1907)
and one other . . .
"A number cited without knowing its degree of uncertainty is meaningless"
Walter Lewin (PhD Physics and professor at MIT)
These two gentlemen laid foundation for my suggestion to our
newest member to the List who was starting to plan his
electrical system, buy parts and start drilling holes.
I suggested that he first make a list of every electrical
load in the airplane and assign its duties in the conduct
of various phases of flight. Those numbers combined with
an assessment of criticality to comfortable continuation
of flight to airport of intended destination is where
one might begin to size the task and make measured
decisions of known significance.
Task I: Measure and tabulate it . . .
Bob . . .
Message 12
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| Subject: | Re: was RV- 14, now electrical redundancy |
".. I don't understand the notion that a 2nd alternator is greatly increased complexity
and effort, therefore all backup must be battery. Once you are
trapped in that thinking, poor trade-offs
result."
Ralph, it is unclear from the context; are you promoting a single battery, dual
alternator system? I don't see any problem with that, given a particular set
of design criteria.
If one of your goals is to maximize endurance after an alternator failure, then
the second alternator makes sense. However, a system with a single battery does
not solve the brown-out at start-up problem.
So it comes down to what's important to you. There is no right or wrong answer
- there can be different designs based upon different sets of constraints & criteria
that result in different, but equally legitimate, designs.
-Jeff
On Saturday, October 25, 2014 10:49 AM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
I don't
understand the notion that a 2nd alternator is greatly increased
complexity and effort, therefore all backup must be battery. Once you are
trapped in that thinking, poor trade-offs
result.
Precisely. "greatly increased" is
non-quantified. To quote from
one of my heros . . .
"When you can measure what you are speaking about, and express
it in numbers, you know something about it; but when you cannot measure
it, when you cannot express it in numbers, your knowledge of it is of a
meager and unsatisfactory kind; it may be the beginning of knowledge, but
you have scarcely, in your thoughts, advanced it to the stage of
science."
Sir William Thompson, Lord Kelvin (1824-1907)
and one other . . .
"A number cited without knowing its degree of uncertainty is
meaningless"
Walter Lewin (PhD Physics and professor at MIT)
These two gentlemen laid foundation for my suggestion to
our
newest member to the List who was starting to plan his
electrical system, buy parts and start drilling
holes.
I suggested that he first make a list of every
electrical
load in the airplane and assign its duties in the
conduct
of various phases of flight. Those numbers combined
with
an assessment of criticality to comfortable
continuation
of flight to airport of intended destination is where
one might begin to size the task and make measured
decisions of known significance.
Task I: Measure and tabulate it . . .
Bob . . .
Message 13
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| Subject: | Re: was RV- 14, now electrical redundancy |
Glen,
What Schotkey diode part number are you using?
Thanks!
Justin
On Oct 25, 2014, at 07:03, GLEN MATEJCEK <fly4grins@gmail.com> wrote:
>> Peter and Jeff-
>
> I wrestled with the same issues, and although I've not yet flown my night /
ifr capable RV yet, I like what I've come up with. The short version is th
at I've a primary efis w/ engine instruments and a backup efis six pack. Gi
ven that cranking and avoiding brown out pretty well required two batteries,
I ultimately adopted Bob's two identical battery, swap one out per year con
cept. The starter, main alternator, main bus (including the switched stby e
fis), and main battery comprise one branch of my system. The essential bat
tery (Sorry folks; I'm not interested in any semantic arguments... call it
a kumquat if you like!) carries the essential bus, which powers the primary
efis un-switched and is supported by an SD-8 on the vacuum pad. The two ba
tteries are tied together with a Schotkey diode, and the SD-8 regulator is s
et between battery and main alternator voltage.
>
> Operation is dirt simple. Starting with the main alt off tests the stby.
In flight, the main alt carries the whole electrical system. Should the ma
in alt fail, the main bus is carried by the main battery and the SD-8 picks u
p the essential bus with precisely zero switch flipping by the pilot. The e
fis will annunciate the drop in main bus voltage. Load shedding at one's le
isure will prolong the life of the main bus, but the SD-8 will ensure all th
e most important goodies have power for probably two hours after the prop st
ops windmilling, even with battery contactors on line.
>
> I use fuses, with the only breakers on power sources. Failure of ANY one c
omponent can't hurt me. YMMV, but I like it, a lot.
>
>
>
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
Message 14
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| Subject: | Re: was RV- 14, now electrical redundancy |
On Sat, Oct 25, 2014 at 11:41 AM, Jeff Luckey <jluckey@pacbell.net> wrote:
> ".. I don't understand the notion that a 2nd alternator is greatly
> increased complexity and effort, therefore all backup must be battery. Once
> you are trapped in that thinking, poor trade-offs result."
>
>
> Ralph, it is unclear from the context; are you promoting a single battery,
> dual alternator system?
>
Not necessarily, two aircraft batteries may be preferable for the OP's
mission and tolerance of risk. I *AM *arguing against the apparent
insistence by at least one here that a 2nd alternator adds such complexity
it should not be considered.
> If one of your goals is to maximize endurance after an alternator failure,
> then the second alternator makes sense. However, a system with a single
> battery does not solve the brown-out at start-up problem.
>
Don't know what that is precisely...if it's important, then put in a 2nd
battery. Sounds like someone is turning on all the avionics, then starting
the engine...if so, couldn't the engine be started, then turn on the glass
panels?
So it comes down to what's important to you. There is no right or wrong
> answer
>
There are multiple solutions or answers to the OP's question, with
different levels of satisfying his requirements. But forgoing a 2nd
alternator because it's "complicated" is not true and is unhelpful.
Message 15
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| Subject: | Re: Wiring RV7 with Z13 diagram (2 alternators, |
1 battery)
I also have the EFII system with redundant ecus.
Make sure you talk with Robert about the mechanical fuel pump in the EFII system.
The issue I see with placing a mechanical fuel pump in the system would be
pressurizing it with an electric fuel pump. The head pressure put out by the EFII
pump module can damage the mechanical pump diaphragms. If one or both diaphragms
begin to leak, you will loose fuel pressure to your injectors and they
will fail to inject fuel into the cylinders, resulting in engine failure.
If you MUST have the mechanical pump in the system, I would suggest that the fuel
from the tanks run thru the mechanical fuel pump first, then thru the EFII
electrical fuel pump module. More plumbing but much safer. I'm sure Robert Paisley
will have an opinion as well.
Hope this helps
Justin
> On Oct 23, 2014, at 07:54, carrollcw <carrollswa@gmail.com> wrote:
>
>
> For now, I just want to get it in the air for day/vfr/acro only. However, I
will later make it fully night IFR.
>
> I am running the dual EFII ignition and fuel injection. Although I will have
a mechanical pump, at least one electric pump must be running to sepply sufficient
pressure.
>
> EI does not have its own power backup. After speaking with Robert at EFII, I
am planning on wiring the 2 ECU's, 2 Ignitions, and 2 Fuel pumps to the always
hot battery bus with switches for each of them, although I was planning on wiring
the fuel pumps with a single dual pole switch.
>
> Basic architecture staying the same. Breakers for e-bus, fuses for everything
else.
>
> Thanks for the help!
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=432174#432174
>
>
>
>
>
>
>
>
>
>
Message 16
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| Subject: | brown out on start |
You can deal with brown out on start by using a deslumpefier designed by Eric
Jones. Right now I have one unit that handles AOA and JPI engine monitor. Works
great, even during hot starts. Also cool fade out on shut down. Im having
a second one built for the GRT HX.
Peter Goudinoff
Lancair Legacy #200
N637PG
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