Today's Message Index:
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1. 04:01 AM - Re: Z14 with SDS EFI... (gtae07)
2. 01:51 PM - Re: Relative position of Transponder and DME antennas (Peter Pengilly)
3. 05:28 PM - Re: Re: Z14 with SDS EFI... (Charlie England)
4. 06:37 PM - Re: order aero electric book and cd bundle about week and a half ago (Robert L. Nuckolls, III)
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Subject: | Re: Z14 with SDS EFI... |
yellowduckduo(at)gmail.co wrote:
> With Z14, I run each of my separate EFI systems off it's own battery buss on
each of my two little 8 amp-Hr batteries. Neither goes thru a battery contactor.
I would not be comfortable running them thru a contactor. There are no "battery
contactors" between the crossfeed and my batteries. I have one contactor
that feeds the non engine busses instead of a classic battery contactor that disconnects
the battery. The general advice here seems to be NOT to plan for 2
independent failures on the same day or you tend to get tied up in overly complicated
knots with little or even sometimes negative safety advantage.
I'm not planning to run engine loads through any contactors. They'd all be wired
right off a battery bus; some components would have their own switches and
others would be hard-wired on (with a fuse to pull if needed for maintenance).
Anything going through a contactor is non-essential or an alternator.
ceengland7(at)gmail.com wrote:
> I can't hit every point, but do have a few thoughts. I wouldn't split injector
power across buses. If you lose a bus & half your injectors, you've lost close
to 75% of your power, & stuff could break just from the abnormal firing with
only two cyls working.
>
> My choice (full disclosure: not yet flying) is to do something closer to what
you have as mod 2. My attitude is to build a good engine bus, make sure my wiring
practice is sound, and live with it, just as I live without backups for my
single pair of wings (redundant controllers on the same bus). I have the luxury
(automotive engine) of running identical alternators, so I have only one battery.
I have one engine bus, controlled with a high current toggle switch (no
contactor) fed directly from the battery utilizing a fusible link in the feed.
The 'rest of the airplane' bus is controlled by a master contactor, as is typical.
I have an emergency crossfeed switch (same high current model) so that
either bus can draw on the other, as needed. I can shut down either alternator's
output, either bus's feed (and crossfeed from the other bus), or if there's
a serious fire, I can still shut down all electrical power if needed as a last
resort ('standard' aviation design practice).
>
> As drawn, your mod 2 has no way to isolate anything from the batteries; the contactors
just interrupt power from the alternators. is that what you intend?
It also doesn't show the 'rest of the airplane' buss (avionics, etc). How will
that be integrated?
"Rest of airplane" loads would come after the contactors, per usual practice.
I'm not worried about those right now.
My biggest concern right now is to make sure the juice (electrical and hydrocarbon)
keeps flowing to the engine. I know running on half the injectors would
be bad so I'm trying to figure out a way around that. The other thing I'm trying
to do is minimize the amount of switch-flipping in the cockpit, and minimize
the number of contacts, break points, etc. between electrical power sources
and my engine. I'm kind of weighing the options between "hard wiring" and putting
a switch on either every component, or on each side of the engine bus.
nuckolls.bob(at)aeroelect wrote:
> At 09:15 AM 7/17/2017, you wrote:
>
> >
> > I'm planning on a dual ECU SDS EFI system for my RV-7. I'm also planning
to (eventually) equip for IFR. Given all that, I'm looking strongly at a Z14-based
electrical architecture, but I have a few questions/concerns about it.
> >
> >
> > My plan was to split the critical engine systems and the PFDs across both
battery buses, so the aircraft could run solely on one bus or the other. I wanted
to maintain the ability to fly indefinitely after one failure and provide
a minimum of two hours on battery power alone.
>
> It seems you have abandoned the fundamental feature of Z-14 . . .
>
> With two alternators, you should be designing for continued flight to intended
destination using the energy from only one of the two alternators.
>
> Batteries are there to add stability to the system dynamics and start the
engine.
>
> Recall that the single most reliable sources of energy on any airplane is
the judiciously maintained battery. Then comes the engine driven alternator .
. . a more prone to failure but still a rare source of anxiety in the cockpit.
>
> Adding a second alternator not only sidesteps probability of declaring an
emergency because of one alternator failure, it also reduces the need for tailoring
battery capacity(ies) to design goals for battery-only endurance.
>
> Have you crafted a load analysis for all electro-whizzies needed for competent/comfortable
termination of flight?
I have. Engine/pump/ECU/coil and PFD load comes to about 12 amps. With radios
and IFR GPS it's closer to 15 amps (IIRC; electrical budget is at work right
now).
nuckolls.bob(at)aeroelect wrote:
> I'm particularly mystified by the spreading of engine critical accessories
across both systems.
The idea is that each bus powers the equipment to keep the engine running by itself.
So, bus 1 powers the primary ECU, the coil driven by the primary ECU, one
fuel pump, etc. and it's enough to keep the engine running on its own.
The secondary bus would power the backup ECU, its coil, the other fuel pump, and
the injector switching relay (which isn't powered when running the primary ECU).
The problem I ran across is that I didn't realize (until I really sat down to start
planning this out) that the injectors were powered separately and just triggered
by the ECU. That means I need to find a way to power all of the injectors
regardless of which bus is online. Unlike ECUs, pumps, and coils, there's
not a redundant set of injectors. I don't know how I'd go about installing
a second set as mentioned by another poster.
nuckolls.bob(at)aeroelect wrote:
> Let's back up. You have two itty-bitty batteries which, I presume, are used
in tandem for cranking. What size alternators? Suppose your engineering design
manager says, "Okay, load up the 4 busses with system accessories and explain
your decisions."
I'm looking at a pair of EarthX ETX900s, which which each have plenty of cranking
juice on their own. Each battery could power the engine loads and PFD for
about 70 minutes, or those plus IFR GPS and radios for almost 50 minutes, based
on their published discharge curves.
Primary bus alternator would be 70A conventional, and the secondary bus a 20A gear-driven.
For the buses:
Main battery - primary ECU/coil/fuel pump, injectors, PFD 1, IFR GPS, (com 1?)
Aux battery - secondary ECU/coil/fuel pump, injectors, injector switching relay,
PFD 2
Main bus - pitot heat, seat heat, 5VDC accessory outlets, flaps, lights
Aux bus - Com 2, ???
nuckolls.bob(at)aeroelect wrote:
> After you have everything hooked up, then do the FMEA . . . what kind of failure
will cause you to re-position some switches? After re-configuration, what
new limits (if any) are imposed on the probability of comfortable termination
of flight?
I'm getting there. Will be working on more detailed wiring today as I'm laid up
from minor surgery.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=471155#471155
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Subject: | Relative position of Transponder and DME antennas |
Hello Bob,
Yes I will have an IFR GPS, and no, the DME isn=99t optional. In
Europe enough approaches have DMEs where the range is
=98slugged=99 to read zero at the threshold that trying to
use GPS will get you in trouble. Sadly Eurocontrol do not have the same
opinion on the substitution of DME with GPS as the FAA. Its bad enough
for an amateur pilot to fly the approach accurately without having to
figure out the actual range!!
Regards, Peter
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
bobsv35b@aol.com
Sent: 18 July 2017 23:53
Subject: Re: AeroElectric-List: Relative position of Transponder and DME
antennas
Good Afternoon Peter,
May I ask whether or not you will have an IFR approved GPS in the RV?
If so, why not forget about installing the DME? The GPS can be used as a
substitute for ANY DME function. Saves time, money, and weight!
Happy Skies,
Old Bob
-----Original Message-----
From: don van santen <donvansanten@gmail.com
<mailto:donvansanten@gmail.com> >
<mailto:aeroelectric-list@matronics.com> >
Sent: Tue, Jul 18, 2017 5:16 pm
Subject: Re: AeroElectric-List: Relative position of Transponder and DME
antennas
Peter,
In my RV all the antennas cables except
the GPS run together down the cold side of the firewall and back in the
wire tunnel. I had to drill s couple holes in the spar carry through bit
Van's daid this was no issue. All the cables are within an inch of each
other. They are all RG400. The length of the runs where they ate
together is roughly six feet.
Antennas are 2 wingtip (archer) 2 com 1transponder/adsb out 1 adsb in
1aprs
Two GPS, 1xm and the GPS for the aprs are under tbe cowl. All have
worked perfectly for nine years now with the atchers working up to 50
miles if over 8000 feet altitude.
On Jul 18, 2017 2:43 PM, "Peter Pengilly" <Peter@sportingaero.com
<mailto:Peter@sportingaero.com> > wrote:
I am retrofitting a panel mount DME into a low wing metal airplane and
trying to figure out where the antenna should be installed.
There are several complicating factors, particularly that it is very
difficult to route the antenna coax from the panel aft past the spar.
The transponder antenna is already placed under the fuselage between the
spar and the firewall under the passenger=99s knees with one comm
(comm 2) antenna in a similar position under the pilot=99s knees.
There is a position for the DMA antenna just ahead of the spar on the
center-line, but this puts it around 15=9D from both of the other
existing antennas. This busts the 36=9D between antennas rule of
thumb =93 but so does the existing comm & txpdr antennas with no
apparent ill effect. However, King recommend the DME antenna should be
more than 3ft from a comm antenna and 6ft from a txpdr antenna. One
method to install the antenna towards the rear of the aircraft could be
to route the coax alongside the comm 1 coax (RG400) for 5ft, but that
appears to be poor practice.
The DME is being installed to support IFR operation and will be used
only infrequently, but when it is needed it will during an instrument
approach and so reliable operation from (say) 10 or 15 miles is highly
desirable. Any degradation in the current good comm or txpdr performance
is undesirable, no matter what the phase of flight.
My questions are,
* Will the installed performance of the DME be noticeably degraded if
the antenna is mounted 15=9D away from an existing comm and txpdr
antenna?
* Will the installed performance of the existing comm and txpdr be
noticeably degraded if the DME antenna is mounted 15=9D away from
both of their existing antennas?
* If the DME & comm RG400 feeders are run in close proximity for 5 feet
will they mutually interfere with each other?
Thanks for any advice,
Peter
Message 3
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Subject: | Re: Z14 with SDS EFI... |
On 7/19/2017 6:00 AM, gtae07 wrote:
>
>
> yellowduckduo(at)gmail.co wrote:
>> With Z14, I run each of my separate EFI systems off it's own battery buss on
each of my two little 8 amp-Hr batteries. Neither goes thru a battery contactor.
I would not be comfortable running them thru a contactor. There are no "battery
contactors" between the crossfeed and my batteries. I have one contactor
that feeds the non engine busses instead of a classic battery contactor that
disconnects the battery. The general advice here seems to be NOT to plan for 2
independent failures on the same day or you tend to get tied up in overly complicated
knots with little or even sometimes negative safety advantage.
> I'm not planning to run engine loads through any contactors. They'd all be wired
right off a battery bus; some components would have their own switches and
others would be hard-wired on (with a fuse to pull if needed for maintenance).
> Anything going through a contactor is non-essential or an alternator.
>
>
snipped////
Not a requirement, but a 'typical' consideration is being able to shut
down the entire electrical system (even the engine's electrical power)
in case of fire or emergency (potential crash) landing for other
possible reasons. Lots of switches/fuses/breakers do make that harder to
manage in an emergency. Not saying don't do it; just do it with eyes
open. My choice is one bus, with two ways to power it. I can take my
system down with one *carefully placed* motion.
---
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Subject: | Re: order aero electric book and cd bundle about |
week and a half ago
Jeff,
Are you sure your 'spam filter' isn't intercepting
PayPal traffic? I've sent you three invoices over
the past few weeks.
Bob . . .
At 07:32 PM 7/16/2017, you wrote:
>recieved confirmation from aeroelectric but never a paypal notice.
>
>
>Jeffrey C Warren
>RV14A #140195
>864-275-3798
><mailto:heffnhane@mac.com>heffnhane@mac.com
>(SC47)
I had invoiced you on the 7th then inadvertently double invoiced a
few days later. When I caught the error, I canceled the second
invoice but it seems that BOTH of them got canceled. You should have
been receiving email notices on each of the snafus . . . Sorry 'bout that!
Just re-issued the invoice . . .
Bob . . .
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