Today's Message Index:
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1. 10:22 AM - Re: SDS CPI-2 Circuit Protection Question (Robert L. Nuckolls, III)
2. 11:39 AM - Re: SDS CPI-2 Circuit Protection Question (Charlie England)
3. 11:49 AM - Re: SDS CPI-2 Circuit Protection Question (Ken Ryan)
4. 02:25 PM - Re: SDS CPI-2 Circuit Protection Question (David Carter)
5. 04:24 PM - Re: SDS CPI-2 Circuit Protection Question (Robert L. Nuckolls, III)
6. 07:50 PM - Re: SDS CPI-2 Circuit Protection Question (Charlie England)
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
>>2. My requirement in my system for a separate engine bus, as stated
>>in other posts, has nothing to do with noise, or resistance, or
>>impedance. It's an *operational* requirement for me, to keep
>>fundamental engine control isolated from fundamental airframe
>>electrical control. 'Mag switches' independent of the airframe
>>'Master switch'. The goal is to mimic as closely as possible the
>>emergency procedures we were all trained to follow when we suspect
>>an electrical issue in flight. The dedicated bus also eliminates
>>multiple potential failure points in the supply path to the engine
>>which are not in the loop in traditional a/c systems (master
>>switch, master contactor, etc).
I am mystified by incorporation of a backup battery with
this system. Are we confessing to an inability to craft
a failure tolerant electrical supply to a DUAL electronic
ignition system?
Will the engine run on ONE of the two systems? If
your engine driven supply is compromised, is there
sufficient standby power generation to sustain
flight? This means your design STARTS with a
load analysis of what items are included on the
plan-b actions list.
This was the kind of thinking from which the endurance
bus was crafted about 30 years ago. Question: how much
WELL MAINTAINED BATTERY is needed to keep the airplane
comfortably airborne for a period of time equal to or
greater than design goals?
I had builders crafting systems in LongEz ships
that would exhaust a full tank of fuel during
battery only operations.
Your design goals are your own but the tools
for achieving them are ancient protocol. Know
your energy budget then provide sources to equal
or exceed that budget as determined by
analysis on the bench and confirmed by
demonstration in the air.
If you've got more than one battery on board,
you're overlooking something. If you have two
engine driven power sources, will the smaller
of the two sustain cruising flight while holding
the battery in reserve for descent and approach
to landing? If you're worrying about multiple
failures of critical items, what are the failure
modes and what are probabilities of loosing
two such devices during the consumption of one
tank of fuel?
The elegant system architecture achieves design
goals with a minimum of hardware, cockpit controls,
weight, cost, etc.
Thought problem: Z101 style engine bus. Triple
energy source (60 + 30 alternators) and a
well maintained battery sized to be determined.
Engine bus energy supplied by two delivery pathways.
All functional engine loads supplied by the bus.
No standby battery.
Failure of what system feature would put this
system at risk for unplanned arrival with the
dirt? What are the limiting factors for achieving
design goals (endurance) after having experienced
the failure?
I am concerned with talk of 'noise' in this
ignition/fuel system? Exactly what has been
demonstrated as a noise problem? Is the source
identified? What appliances are victims of this
'noise'? What is being done to bring the
antagonist into a neighborly coexistence with
all players in the electrical sandbox?
Message 2
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
On 9/28/2021 12:21 PM, Robert L. Nuckolls, III wrote:
>>> 2. My requirement in my system for a separate engine bus, as stated
>>> in other posts, has nothing to do with noise, or resistance, or
>>> impedance. It's an *operational* requirement for me, to keep
>>> fundamental engine control isolated from fundamental airframe
>>> electrical control. 'Mag switches' independent of the airframe
>>> 'Master switch'. The goal is to mimic as closely as possible the
>>> emergency procedures we were all trained to follow when we suspect
>>> an electrical issue in flight. The dedicated bus also eliminates
>>> multiple potential failure points in the supply path to the engine
>>> which are not in the loop in traditional a/c systems (master switch,
>>> master contactor, etc).
>
> I am mystified by incorporation of a backup battery with
> this system. Are we confessing to an inability to craft
> a failure tolerant electrical supply to a DUAL electronic
> ignition system?
>
> Will the engine run on ONE of the two systems? If
> your engine driven supply is compromised, is there
> sufficient standby power generation to sustain
> flight? This means your design STARTS with a
> load analysis of what items are included on the
> plan-b actions list.
>
> This was the kind of thinking from which the endurance
> bus was crafted about 30 years ago. Question: how much
> WELL MAINTAINED BATTERY is needed to keep the airplane
> comfortably airborne for a period of time equal to or
> greater than design goals?
>
> I had builders crafting systems in LongEz ships
> that would exhaust a full tank of fuel during
> battery only operations.
>
> Your design goals are your own but the tools
> for achieving them are ancient protocol. Know
> your energy budget then provide sources to equal
> or exceed that budget as determined by
> analysis on the bench and confirmed by
> demonstration in the air.
>
> If you've got more than one battery on board,
> you're overlooking something. If you have two
> engine driven power sources, will the smaller
> of the two sustain cruising flight while holding
> the battery in reserve for descent and approach
> to landing? If you're worrying about multiple
> failures of critical items, what are the failure
> modes and what are probabilities of loosing
> two such devices during the consumption of one
> tank of fuel?
>
> The elegant system architecture achieves design
> goals with a minimum of hardware, cockpit controls,
> weight, cost, etc.
>
> Thought problem: Z101 style engine bus. Triple
> energy source (60 + 30 alternators) and a
> well maintained battery sized to be determined.
> Engine bus energy supplied by two delivery pathways.
> All functional engine loads supplied by the bus.
> No standby battery.
>
> Failure of what system feature would put this
> system at risk for unplanned arrival with the
> dirt? What are the limiting factors for achieving
> design goals (endurance) after having experienced
> the failure?
>
> I am concerned with talk of 'noise' in this
> ignition/fuel system? Exactly what has been
> demonstrated as a noise problem? Is the source
> identified? What appliances are victims of this
> 'noise'? What is being done to bring the
> antagonist into a neighborly coexistence with
> all players in the electrical sandbox?
>
Uh, not that I disagree with most of what you wrote, but you quoted my
response to the OP, not his posts. :-) I did *speculate* on several
different possible reasons that SDS recommended separate feeders for the
ECU vs coils and/or injectors.
I do think you need to remember that this:
/I had builders crafting systems in LongEz ships//
// that would exhaust a full tank of fuel during//
// battery only operations.
/only applies to mags, or electronic ignition-only systems. The combo of
electronic ignition, electronic injectors, and high current fuel pump
means that a PC680 equivalent battery is good for about 40 minutes, as
long as all other airframe electrical loads are minimal. If there are
5-10 amps of unshed panel loads (not unusual these days), battery-only
operation could be as short as 15-20 minutes.
Automotive style injection changes the battery-only operation equations
by a bunch.
Thanks,
Charlie
/
/
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Message 3
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
Wearing a "belt and suspenders" is not elegant, but it is not necessarily a
bad idea either.
On Tue, Sep 28, 2021 at 10:43 AM Charlie England <ceengland7@gmail.com>
wrote:
> On 9/28/2021 12:21 PM, Robert L. Nuckolls, III wrote:
>
> 2. My requirement in my system for a separate engine bus, as stated in
> other posts, has nothing to do with noise, or resistance, or impedance.
> It's an *operational* requirement for me, to keep fundamental engine
> control isolated from fundamental airframe electrical control. 'Mag
> switches' independent of the airframe 'Master switch'. The goal is to mimic
> as closely as possible the emergency procedures we were all trained to
> follow when we suspect an electrical issue in flight. The dedicated bus
> also eliminates multiple potential failure points in the supply path to the
> engine which are not in the loop in traditional a/c systems (master switch,
> master contactor, etc).
>
>
> I am mystified by incorporation of a backup battery with
> this system. Are we confessing to an inability to craft
> a failure tolerant electrical supply to a DUAL electronic
> ignition system?
>
> Will the engine run on ONE of the two systems? If
> your engine driven supply is compromised, is there
> sufficient standby power generation to sustain
> flight? This means your design STARTS with a
> load analysis of what items are included on the
> plan-b actions list.
>
> This was the kind of thinking from which the endurance
> bus was crafted about 30 years ago. Question: how much
> WELL MAINTAINED BATTERY is needed to keep the airplane
> comfortably airborne for a period of time equal to or
> greater than design goals?
>
> I had builders crafting systems in LongEz ships
> that would exhaust a full tank of fuel during
> battery only operations.
>
> Your design goals are your own but the tools
> for achieving them are ancient protocol. Know
> your energy budget then provide sources to equal
> or exceed that budget as determined by
> analysis on the bench and confirmed by
> demonstration in the air.
>
> If you've got more than one battery on board,
> you're overlooking something. If you have two
> engine driven power sources, will the smaller
> of the two sustain cruising flight while holding
> the battery in reserve for descent and approach
> to landing? If you're worrying about multiple
> failures of critical items, what are the failure
> modes and what are probabilities of loosing
> two such devices during the consumption of one
> tank of fuel?
>
> The elegant system architecture achieves design
> goals with a minimum of hardware, cockpit controls,
> weight, cost, etc.
>
> Thought problem: Z101 style engine bus. Triple
> energy source (60 + 30 alternators) and a
> well maintained battery sized to be determined.
> Engine bus energy supplied by two delivery pathways.
> All functional engine loads supplied by the bus.
> No standby battery.
>
> Failure of what system feature would put this
> system at risk for unplanned arrival with the
> dirt? What are the limiting factors for achieving
> design goals (endurance) after having experienced
> the failure?
>
> I am concerned with talk of 'noise' in this
> ignition/fuel system? Exactly what has been
> demonstrated as a noise problem? Is the source
> identified? What appliances are victims of this
> 'noise'? What is being done to bring the
> antagonist into a neighborly coexistence with
> all players in the electrical sandbox?
>
>
> Uh, not that I disagree with most of what you wrote, but you quoted my
> response to the OP, not his posts. :-) I did *speculate* on several
> different possible reasons that SDS recommended separate feeders for the
> ECU vs coils and/or injectors.
>
> I do think you need to remember that this:
>
> *I had builders crafting systems in LongEz ships*
> * that would exhaust a full tank of fuel during*
>
>
> * battery only operations. *only applies to mags, or electronic
> ignition-only systems. The combo of electronic ignition, electronic
> injectors, and high current fuel pump means that a PC680 equivalent battery
> is good for about 40 minutes, as long as all other airframe electrical
> loads are minimal. If there are 5-10 amps of unshed panel loads (not
> unusual these days), battery-only operation could be as short as 15-20
> minutes.
>
> Automotive style injection changes the battery-only operation equations by
> a bunch.
>
> Thanks,
>
> Charlie
>
>
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=icon> Virus-free.
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Message 4
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
Let's also recall that the CPI-2 is an ignition-only product. It does not
provide fuel injection. The PC680 would run much longer powering just a
dual CPI-2 & minimal other loads. That said, I have two alternators & a
single battery (Z101 architecture) in my CPI-2 equipped plane. As long as
there is gas to power the engine, the ignition should have electrons. The
redundantly-powered engine bus supplies both the primary & backup power
feeds to both CPI-2 ECUs & coils.
---
David Carter
david@carter.net
On Tue, Sep 28, 2021 at 2:40 PM Charlie England <ceengland7@gmail.com>
wrote:
> On 9/28/2021 12:21 PM, Robert L. Nuckolls, III wrote:
>
> 2. My requirement in my system for a separate engine bus, as stated in
> other posts, has nothing to do with noise, or resistance, or impedance.
> It's an *operational* requirement for me, to keep fundamental engine
> control isolated from fundamental airframe electrical control. 'Mag
> switches' independent of the airframe 'Master switch'. The goal is to mimic
> as closely as possible the emergency procedures we were all trained to
> follow when we suspect an electrical issue in flight. The dedicated bus
> also eliminates multiple potential failure points in the supply path to the
> engine which are not in the loop in traditional a/c systems (master switch,
> master contactor, etc).
>
>
> I am mystified by incorporation of a backup battery with
> this system. Are we confessing to an inability to craft
> a failure tolerant electrical supply to a DUAL electronic
> ignition system?
>
> Will the engine run on ONE of the two systems? If
> your engine driven supply is compromised, is there
> sufficient standby power generation to sustain
> flight? This means your design STARTS with a
> load analysis of what items are included on the
> plan-b actions list.
>
> This was the kind of thinking from which the endurance
> bus was crafted about 30 years ago. Question: how much
> WELL MAINTAINED BATTERY is needed to keep the airplane
> comfortably airborne for a period of time equal to or
> greater than design goals?
>
> I had builders crafting systems in LongEz ships
> that would exhaust a full tank of fuel during
> battery only operations.
>
> Your design goals are your own but the tools
> for achieving them are ancient protocol. Know
> your energy budget then provide sources to equal
> or exceed that budget as determined by
> analysis on the bench and confirmed by
> demonstration in the air.
>
> If you've got more than one battery on board,
> you're overlooking something. If you have two
> engine driven power sources, will the smaller
> of the two sustain cruising flight while holding
> the battery in reserve for descent and approach
> to landing? If you're worrying about multiple
> failures of critical items, what are the failure
> modes and what are probabilities of loosing
> two such devices during the consumption of one
> tank of fuel?
>
> The elegant system architecture achieves design
> goals with a minimum of hardware, cockpit controls,
> weight, cost, etc.
>
> Thought problem: Z101 style engine bus. Triple
> energy source (60 + 30 alternators) and a
> well maintained battery sized to be determined.
> Engine bus energy supplied by two delivery pathways.
> All functional engine loads supplied by the bus.
> No standby battery.
>
> Failure of what system feature would put this
> system at risk for unplanned arrival with the
> dirt? What are the limiting factors for achieving
> design goals (endurance) after having experienced
> the failure?
>
> I am concerned with talk of 'noise' in this
> ignition/fuel system? Exactly what has been
> demonstrated as a noise problem? Is the source
> identified? What appliances are victims of this
> 'noise'? What is being done to bring the
> antagonist into a neighborly coexistence with
> all players in the electrical sandbox?
>
>
> Uh, not that I disagree with most of what you wrote, but you quoted my
> response to the OP, not his posts. :-) I did *speculate* on several
> different possible reasons that SDS recommended separate feeders for the
> ECU vs coils and/or injectors.
>
> I do think you need to remember that this:
>
> *I had builders crafting systems in LongEz ships*
> * that would exhaust a full tank of fuel during*
>
>
> * battery only operations. *only applies to mags, or electronic
> ignition-only systems. The combo of electronic ignition, electronic
> injectors, and high current fuel pump means that a PC680 equivalent battery
> is good for about 40 minutes, as long as all other airframe electrical
> loads are minimal. If there are 5-10 amps of unshed panel loads (not
> unusual these days), battery-only operation could be as short as 15-20
> minutes.
>
> Automotive style injection changes the battery-only operation equations by
> a bunch.
>
> Thanks,
>
> Charlie
>
>
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient&utm_term=icon> Virus-free.
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Message 5
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
>
>I do think you need to remember that this:
>
>I had builders crafting systems in LongEz ships
> that would exhaust a full tank of fuel during
> battery only operations.
>
>only applies to mags, or electronic ignition-only systems. The combo
>of electronic ignition, electronic injectors, and high current fuel
>pump means that a PC680 equivalent battery is good for about 40
>minutes, as long as all other airframe electrical loads are minimal.
>If there are 5-10 amps of unshed panel loads (not unusual these
>days), battery-only operation could be as short as 15-20 minutes.
>
>Automotive style injection changes the battery-only operation
>equations by a bunch.
How big is 'a bunch'? I'm not suggesting that
anyone strive for multi-hour cruising ops
battery only either. I'm reading a lot of
discussion wrapped in worries with
zero quantitative analysis for meeting an
as yet un-defined design goal. There's
also a sprinkling of worries about multiple
failures which are exceedingly rare.
We had some discussions here on the List
years ago on this same topic. Some of the
participants were really hard over on
keeping BOTH ignitions running when the
engine performance was adequate on one
ignition with a significant savings of
endurance energy.
Those few Ez drivers looking for extra
ordinary battery-only endurance were flying
SD-8 but most LongEz projects needed nose
ballast. So why not make it 'useful lead'
as opposed to 'dead lead'?
Seems the really important question for
a dual alternator system is whether or not
one can sustain flight on the smaller of
the two alternators? Can CRUISING loads
be reduced to a value that CAN be supported?
If you can do that, then combined with a
properly maintained battery you've got
power to burn. Once the airport is in sight,
fire up all the electro-whizzies.
But to validate that plan-b, you need ENERGY
requirements and a checklist of what can be
put in reserve during endurance cruise.
There's a youtube presentation that measures
energy demands for this ignition system. Haven't
found one for the fuel system.
One would to well to know exactly what the
energy demands are for running an engine
fitted with these systems. We have to do
it to TC a spam-can . . . there's a good
reason for that!
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 6
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
On 9/28/2021 6:23 PM, Robert L. Nuckolls, III wrote:
>>
>> I do think you need to remember that this:
>>
>> /I had builders crafting systems in LongEz ships
>> that would exhaust a full tank of fuel during
>> battery only operations.
>>
>> /only applies to mags, or electronic ignition-only systems. The combo
>> of electronic ignition, electronic injectors, and high current fuel
>> pump means that a PC680 equivalent battery is good for about 40
>> minutes, as long as all other airframe electrical loads are minimal.
>> If there are 5-10 amps of unshed panel loads (not unusual these
>> days), battery-only operation could be as short as 15-20 minutes.
>>
>> Automotive style injection changes the battery-only operation
>> equations by a bunch.
>
> How big is 'a bunch'? I'm not suggesting that
> anyone strive for multi-hour cruising ops
> battery only either. I'm reading a lot of
> discussion wrapped in worries with
> zero quantitative analysis for meeting an
> as yet un-defined design goal. There's
> also a sprinkling of worries about multiple
> failures which are exceedingly rare.
>
> We had some discussions here on the List
> years ago on this same topic. Some of the
> participants were really hard over on
> keeping BOTH ignitions running when the
> engine performance was adequate on one
> ignition with a significant savings of
> endurance energy.
>
> Those few Ez drivers looking for extra
> ordinary battery-only endurance were flying
> SD-8 but most LongEz projects needed nose
> ballast. So why not make it 'useful lead'
> as opposed to 'dead lead'?
>
> Seems the really important question for
> a dual alternator system is whether or not
> one can sustain flight on the smaller of
> the two alternators? Can CRUISING loads
> be reduced to a value that CAN be supported?
>
> If you can do that, then combined with a
> properly maintained battery you've got
> power to burn. Once the airport is in sight,
> fire up all the electro-whizzies.
>
> But to validate that plan-b, you need ENERGY
> requirements and a checklist of what can be
> put in reserve during endurance cruise.
>
> There's a youtube presentation that measures
> energy demands for this ignition system. Haven't
> found one for the fuel system.
>
> One would to well to know exactly what the
> energy demands are for running an engine
> fitted with these systems. We have to do
> it to TC a spam-can . . . there's a good
> reason for that!
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Well, I didn't just pull those numbers out of one of my body's orifices.
;-) I'm pretty sure that if you ask SDS or any of the other automotive
injection makers, they'll quote a number in the 10A+ range, minimum.
A single automotive style injection system, when the injection pump is
included, is going to draw at least 10 amps; likely closer to 15 amps to
keep the engine running. The 40 minutes of PC680 battery-only endurance
was demonstrated by an engineer friend during testing of his new
electronic injected RV9A (back in the pre-EFIS days, with minimal
current draw from the instrument panel), and can be sanity checked using
Odyssey's published discharge curves. He did the test in the air,
alternator off, at low/mid engine power levels, and discontinued the
test (brought the alternator back on line) when battery voltage equaled
Odyssey's published voltage for a discharged battery.
I repeat: It's not about keeping two, or even one, *ignitions* running.
It's about keeping the entire engine control system running, which
includes not just the ignition (most of the auto style systems will fire
all the plugs, by default), but the injectors (which require
quantifiable higher current than the coils), the ECU (relatively low
power of an amp or two, but certainly not insignificant), and the fuel
pump, which is significant at a bare minimum of 4-6 amps, and more
typically at 6-8 amps.
The alternative engine guys have been dealing with this for at least a
decade or two longer than the 'traditional' aircraft engine guys and the
numbers I'm giving have been pretty consistent among multiple users for
many years.
Charlie
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