Today's Message Index:
----------------------
1. 06:17 AM - Re: Z-19RB clarification (Roger)
2. 09:27 AM - Re: Z-19RB clarification (Allen Fulmer)
3. 10:03 AM - Re: Z-19RB clarification (ROGER & JEAN CURTIS)
4. 04:57 PM - Re: Z-19RB clarification (Robert L. Nuckolls, III)
5. 04:57 PM - Re: Z-19RB clarification (Robert L. Nuckolls, III)
6. 05:12 PM - Re: Z-19RB clarification (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Z-19RB clarification |
Allen,
Thanks for your input, also thanks again for the use of your panel punch
(best way to make nice clean instrument holes).
In my thinking, I was approaching this from a slightly different angle. In
IFR conditions if the main battery goes dead, because you had a hard engine
start and not sufficient time to recharge the main you have no avionics to
get you to VFR conditions. In this case a running engine does you no good.
But, to put a little more logic into the situation, you should be seeking an
out from IFR asap to improve your chances if something else does go wrong.
My slight mod, mentioned previously, to Z-19RB:
Since I have dual ignition and dual fuel pumps, I am eliminating the diodes
and the 2-3 switches, to be replaced with 4ea. SPST, thus simplifying and
also giving me full control of any combination of fuel pumps and ignition.
> <afulmer@charter.net>
>
> Roger,
> I am using Z-19RB in my Subaru H6 powered RV7. My understanding as to why
> the endurance bus alternate feed is from the Main Battery only is that the
> engine bus and its battery are reserved for the running of the engine
> alone
> just as long as possible. I guess if you lose the main battery and thus
> the
> endurance bus then you can still fly the airplane to a safe landing site
> as
> long as the engine is running. Whereas, if you lose the engine
> battery/bus
> the endurance bus is not going to do you any good as you glide to a
> landing.
>
> I am sure Bob will chime in with a more elegant explanation.
> Allen Fulmer
> RV7 Finishing wiring
> Subaru hanging and run
> N808AF reserved
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of ROGER &
> JEAN CURTIS
> Sent: Wednesday, July 04, 2012 6:09 PM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: Z-19RB clarification
>
> <mrspudandcompany@verizon.net>
>
> I plan to use a slightly modified version of Z-19RB in my aircraft. It
> appears to me that during an alternator failure you would want to
> deenergize
> both the Main battery contactor and the Engine battery contactor, to
> conserve battery power. In doing this there is no power available from
> the
> engine battery to the endurance bus. The endurance bus alternate feed is
> the only power feed path to this bus, with the contactors deenergized.
>
> My question is, am I missing something, was this overlooked in the design
> phase, or is there a specific reason for this design philosophy?
>
> Thanks,
>
> Roger
Message 2
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| Subject: | Z-19RB clarification |
It will be interesting to see how long the Subaru will run on one battery if
the alternator goes out.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Roger
Sent: Thursday, July 05, 2012 8:16 AM
Subject: Re: AeroElectric-List: Z-19RB clarification
<mrspudandcompany@verizon.net>
Allen,
Thanks for your input, also thanks again for the use of your panel punch
(best way to make nice clean instrument holes).
In my thinking, I was approaching this from a slightly different angle. In
IFR conditions if the main battery goes dead, because you had a hard engine
start and not sufficient time to recharge the main you have no avionics to
get you to VFR conditions. In this case a running engine does you no good.
But, to put a little more logic into the situation, you should be seeking an
out from IFR asap to improve your chances if something else does go wrong.
My slight mod, mentioned previously, to Z-19RB:
Since I have dual ignition and dual fuel pumps, I am eliminating the diodes
and the 2-3 switches, to be replaced with 4ea. SPST, thus simplifying and
also giving me full control of any combination of fuel pumps and ignition.
> <afulmer@charter.net>
>
> Roger,
> I am using Z-19RB in my Subaru H6 powered RV7. My understanding as to why
> the endurance bus alternate feed is from the Main Battery only is that the
> engine bus and its battery are reserved for the running of the engine
> alone
> just as long as possible. I guess if you lose the main battery and thus
> the
> endurance bus then you can still fly the airplane to a safe landing site
> as
> long as the engine is running. Whereas, if you lose the engine
> battery/bus
> the endurance bus is not going to do you any good as you glide to a
> landing.
>
> I am sure Bob will chime in with a more elegant explanation.
> Allen Fulmer
> RV7 Finishing wiring
> Subaru hanging and run
> N808AF reserved
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of ROGER &
> JEAN CURTIS
> Sent: Wednesday, July 04, 2012 6:09 PM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: Z-19RB clarification
>
> <mrspudandcompany@verizon.net>
>
> I plan to use a slightly modified version of Z-19RB in my aircraft. It
> appears to me that during an alternator failure you would want to
> deenergize
> both the Main battery contactor and the Engine battery contactor, to
> conserve battery power. In doing this there is no power available from
> the
> engine battery to the endurance bus. The endurance bus alternate feed is
> the only power feed path to this bus, with the contactors deenergized.
>
> My question is, am I missing something, was this overlooked in the design
> phase, or is there a specific reason for this design philosophy?
>
> Thanks,
>
> Roger
Message 3
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| Subject: | Z-19RB clarification |
It will be interesting to see how long the Subaru will run on one battery if
the alternator goes out.
Allen,
You should do some tests to see what the electrical load is on each battery
with alternator off and endurance bus on. Then check the capacity of your
batteries at these loads. I plan to do a battery test as a part of my
annual inspection.
Roger
Message 4
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| Subject: | Re: Z-19RB clarification |
At 08:16 AM 7/5/2012, you wrote:
><mrspudandcompany@verizon.net>
>
>In my thinking, I was approaching this from a slightly different
>angle. In IFR conditions if the main battery goes dead, because you
>had a hard engine start and not sufficient time to recharge the
>main you have no avionics to get you to VFR conditions. In this
>case a running engine does you no good. But, to put a little more
>logic into the situation, you should be seeking an out from IFR asap
>to improve your chances if something else does go wrong.
How do you kill a main battery and not the engine
battery too? Why would you launch into IFR after
an anomalous engine start with knowledge that the
battery(ies) are now less than optimal? How much 'avionics'
do you 'need' to navigate to VMC? What's then energy
budget? How would you position switches and reduce
loads to maximize available resources . . . indeed,
what policies and procedures will you put in place
to always KNOW what your resources are?
>My slight mod, mentioned previously, to Z-19RB:
>Since I have dual ignition and dual fuel pumps, I am eliminating the
>diodes and the 2-3 switches, to be replaced with 4ea. SPST, thus
>simplifying and also giving me full control of any combination of
>fuel pumps and ignition.
But 'full control' over what? Flying an airplane
is like baking a cake. You cannot make useful changes
to a recipe AFTER the batter is in the pan. Z-19
was designed to deal comfortably with one annunciated
failure. Launching into unfriendly conditions without
KNOWING that your Plan-B energy budget can be met is
the first failure . . . stacking a "dead battery" on
top of that is a second failure . . . adding a dead
alternator to that is a third failure. Sounds like
the script to a Hollywood dark-n-stormy night movie.
Sorry my friend, all the switches offering back-ups to
back-ups is the very last thing you need in single-pilot
IFR. Please review chapter 17 and apply the logic to your
own cake recipe. The chapter is a bit dated given the
much heavier e-bus loads but the principal for careful
study of system loads, knowing limits to energy sources
and insuring timely pilot awareness and SIMPLE response
is critical to an effective Plan-B. When the LO VOLTS
light comes on, you say 'oh fooey' and reposition a
couple of switches at most then get on with the task
of putting your wheels on the pavement without breaking
a sweat.
Adding plans C, D, E and F with lots of new options
for total control is an invitation to an unhappy
day in the cockpit. Launching with known deficiencies
is performance or resources is like hitting the highway
for a run to the mountains in a dust storm and 100 miles
between towns knowing you're a quart low on oil, one tire
is half inflated, or remembering you left your Dopp kit
on the bed. Each deficiency adds its own level of
uncertainty or risk to the trip. Stack them on top of each
other and you may have created a situation that no
amount of extra features in the flipping of switches
is going to help.
Bob . . .
Message 5
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| Subject: | Re: Z-19RB clarification |
At 08:16 AM 7/5/2012, you wrote:
In my thinking, I was approaching this from a slightly different
angle. In IFR conditions if the main battery goes dead, because you
had a hard engine start and not sufficient time to recharge the main
you have no avionics to get you to VFR conditions. In this case a
running engine does you no good. But, to put a little more logic into
the situation, you should be seeking an out from IFR asap to improve
your chances if something else does go wrong.
How do you kill a main battery and not the engine
battery too? Why would you launch into IFR after
an anomalous engine start with knowledge that the
battery(ies) are now less than optimal? How much 'avionics'
do you 'need' to navigate to VMC? What's then energy
budget? How would you position switches and reduce
loads to maximize available resources . . . indeed,
what policies and procedures will you put in place
to always KNOW what your resources are?
My slight mod, mentioned previously, to Z-19RB:
Since I have dual ignition and dual fuel pumps, I am eliminating the
diodes and the 2-3 switches, to be replaced with 4ea. SPST, thus
simplifying and also giving me full control of any combination of
fuel pumps and ignition.
But 'full control' over what? Flying an airplane
is like baking a cake. You cannot make useful changes
to a recipe AFTER the batter is in the pan. Z-19
was designed to deal comfortably with one annunciated
failure. Launching into unfriendly conditions without
KNOWING that your Plan-B energy budget can be met is
the first failure . . . stacking a "dead battery" on
top of that is a second failure . . . adding a dead
alternator to that is a third failure. Sounds like
the script to a Hollywood dark-n-stormy night movie.
Sorry my friend, all the switches offering back-ups to
back-ups is the very last thing you need in single-pilot
IFR. Please review chapter 17 and apply the logic to your
own cake recipe. The chapter is a bit dated given the
much heavier e-bus loads but the principal for careful
study of system loads, knowing limits to energy sources
and insuring timely pilot awareness and SIMPLE response
is critical to an effective Plan-B. When the LO VOLTS
light comes on, you say 'oh fooey' and reposition a
couple of switches at most then get on with the task
of putting your wheels on the pavement without breaking
a sweat.
Adding plans C, D, E and F with lots of new options
for total control is an invitation to an unhappy
day in the cockpit. Launching with known deficiencies
is performance or resources is like hitting the highway
for a run to the mountains in a dust storm and 100 miles
between towns knowing you're a quart low on oil, one tire
is half inflated, or remembering you left your Dopp kit
on the bed. Each deficiency adds its own level of
uncertainty or risk to the trip. Stack them on top of each
other and you may have created a situation that no
amount of extra features in the flipping of switches
is going to help.
Bob . . .
Message 6
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| Subject: | Z-19RB clarification |
At 09:52 PM 7/4/2012, you wrote:
Roger,
I am using Z-19RB in my Subaru H6 powered RV7. My understanding as to why
the endurance bus alternate feed is from the Main Battery only is that the
engine bus and its battery are reserved for the running of the engine alone
just as long as possible. I guess if you lose the main battery and thus the
endurance bus then you can still fly the airplane to a safe landing site as
long as the engine is running. Whereas, if you lose the engine battery/bus
the endurance bus is not going to do you any good as you glide to a landing.
I am sure Bob will chime in with a more elegant explanation.
During normal operations, BOTH batteries are on
line and behave as a single battery equal to their
combined capacity.
When the low volts warning light comes on, all you
have to finish the flight is what ever is carried
in the two batteries.
At that point in time you drop to the ENDURANCE MODE.
Run no piece of equipment that is not necessary for
a no-sweat return to earth.
Repeat after me: "I will KNOW what the capacity of
my batteries is at all times by which I will KNOW
what my endurance limits are in alternator-out
conditions." This usually calls for getting the
battery contactors out of the picture . . . turning
off both battery switches, running the engine from
the engine battery and minimum electro-whizzies on
the endurance bus. Once you have the airport in sight
and are cleared to land, you can turn the main battery
back on and use what ever is left to make a grander
entrance . . . but the idea is that you've kept
the engine's power source fire-walled off in a
separate energy bucket.
Now, if you want to add a second failure to this
scenario, then BOTH battery switches are placed to
ON and you begin moves to expedite landing while
watching bus voltage readings. When it gets down
to 10.5 volts, your on-board battery energy is
more than 95% used up. You need to be on short
final before that time.
Being able to switch the engine from one battery
to the other is a hedge against contactor failure
stacked on top of other failures . . . a statistical
tiny dot on the great horizon of possibilities for
one failure.
Bob . . .
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