Today's Message Index:
----------------------
1. 06:42 AM - Re: Sil Pad For Schottky Diode (Robert L. Nuckolls, III)
2. 07:22 AM - Hour-meter switch from 3-phase tach generator (Robert L. Nuckolls, III)
3. 07:24 AM - One or Two batteries with Single Alternator for Electric Airplane (Kevin Sheely)
4. 09:12 AM - Re: stopping engine (Kenneth Johnson)
5. 09:21 AM - Re: Big load on BAT BUS (jonlaury)
6. 09:42 AM - Re: stopping engine (Mike Fontenot)
7. 10:11 AM - Re: stopping engine (Bill Bradburry)
8. 10:54 AM - Re: stopping engine (Bill Bradburry)
9. 11:09 AM - Re: stopping engine (Matt Prather)
10. 07:49 PM - Electrical diagram (marchudson)
11. 08:12 PM - Re: stopping engine (Bill Schertz)
12. 08:36 PM - Re: One or Two batteries with Single Alternator for Electric Airplane (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Sil Pad For Schottky Diode |
At 08:39 PM 4/27/2010, you wrote:
>Bob,
>I bought a Schottky Diode from you roughly one year ago. I
>installed it today and was unable to get the device mounted so that
>there was no conductivity between the load screw and the mounting
>plate. I did not use excessive force on the screw and the holes are
>all clean. I think the Sil Pad got damaged in the install. Can I
>buy another one from you ?
Shoot me your address and I'll send you one.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 2
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Subject: | Hour-meter switch from 3-phase tach generator |
Some weeks back we had a discussion about how to switch
a Hobbs meter on and off based on activity at the
3-phase tach generator. I thought we'd 'wrapped up'
that discussion but I found a drawing under a stack
of stuff that apparently didn't get posted. For
those interested in such things, see:
http://aeroelectric.com/Pictures/Schematics/Hour-Meter_from_3-Phase_Tach.pdf
The opto-couplers can be anything with an open
collector, transistor output.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 3
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Subject: | One or Two batteries with Single Alternator for Electric |
Airplane
Bob,=0A=0AWhich architecture should I be using for a VFR, day/night, single
engine dual LSE ignition, single B&C 30 amp alternator and single MGL EFIS
, radio, transponder, intercom?=0A=0AMy emergency power draw would be 6.7 a
mps (cruise-is 12.34 amps). I could use a single battery but would like t
o have a second smaller 5-7 amp battery as a backup for the EFIS and-one
of the LSE ignitions.=0A=0ARegards,=0AKevin
Message 4
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Subject: | Re: stopping engine |
Hi All,=0AI would like to thank all who responded.=C2- =0A=0AIt would see
m the best reason to stop an engine with fuel starvation would be to preven
t possible danger from the prop.=C2- If a prop was repositioned, fuel in
a cylinder might ignite, which in turn would turn the prop and that might h
urt someone.=C2- In an automobile, if dieseling=C2-occurs, no is hurt.
=C2- The car is in "Park" or "Neutral."=0A=0AI have a Mazda rotary engine
I will be using for my airplane.=C2- Eventhough this is not a piston eng
ine, the threat of danger from the prop with fuel left in the burn chamber
still exists.=C2- For safety reasons, fuel starvation would be the best w
ay to stop the engine.=C2- Turning off the ignition will stop current to
the spark plugs, coils,=C2-and will turn off the high pressure fuel pump.
=C2- However, it would seem that turning off the fuel pump before turning
off the ignition would be a safer way to eliminate fuel from the burn cham
bers.=0A=0ABy using a valve on my fuel rail, I could stop fuel.=C2- Howev
er, the fuel pump would still be working and could be damaged.=C2- Again,
it would seem that switching off the fuel pump=C2-before the ignition=C2
-might be the best solution.=C2- =0A=0AIf anyone has a better solution,
please post.=0A=0AThanks,=0A=0AKen Johnson=C2-=C2-=0A=0A=0A=0A=0A_____
___________________________=0AFrom: Matt Prather <mprather@spro.net>=0ATo:
aeroelectric-list@matronics.com=0ASent: Tue, April 27, 2010 1:54:43 PM=0ASu
bject: RE: AeroElectric-List: stopping engine=0A=0A--> AeroElectric-List me
ssage posted by: "Matt Prather" <mprather@spro.net>=0A=0AI think it's worth
while to be precise (reduce ambiguity) in matters such=0Aas this.=0A=0AI be
lieve many (most?) light airplane POH's specify that engine shutdown=0Ais a
ccomplished by moving the mixture control to idle-cutoff (ICO).=0AUsually t
his causes the engine to stop running fairly rapidly - in a=0Amatter of a c
ouple of seconds.=C2- Selecting rich mixture and hitting the=0Astarter us
ually allows the engine to restart very quickly/easily.=0A=0ACertainly many
airplanes still have Stromberg carbs (or similar) which=0Adon't have a mix
ture control effective enough to cause "idle-cutoff".=C2- I=0Ahave ridden
with pilots of such airplanes who only use the magneto=0Aswitches to stop
the engine.=C2- One benefit of this procedure is that you=0Acheck to see
if you have a "hot mag" on each flight.=C2- If the engine stops=0Adead, y
ou can be somewhat certain that the p-lead circuit is in working=0Aconditio
n.=0A=0AMost (all?) light airplanes also have at least one fuel control val
ve=0A(selector), which can also be used to stop the flow of fuel to the eng
ine.=0AOn the carbureted engines that I have operated, closing this fuel va
lve=0Adoes eventually stop the engine, though depending on how low the thro
ttle=0Asetting is, it might take a few minutes for the float bowl in the ca
rb to=0Aget low enough to cause the engine to lean-out and die.=C2- Usual
ly when I=0Apull up to a parking spot, I don't feel like waiting for the ca
rb to=0Aempty, so I never do this.=0A=0AIf the fuel valve was turned off, o
n carbureted airplanes with gravity=0Afeed fuel, turning on the fuel valve
and waiting a few moments will refill=0Athe carb float bowl, at which point
the engine may be restarted.=C2- For an=0Aairplane with pump driven fuel
, turning on the electric pump will allow=0Arestarting much faster/sooner t
han if only the engine driven pump is used.=0ATurning on the electric pump
is often in the engine start procedure.=0A=0AIn an airplane that depends on
a high pressure electric pump, I'm not sure=0Ait makes sense to "turn off
the fuel," if that implies closing some kind=0Aof fuel valve.=C2- It migh
t make more sense to turn off the electric pump(s).=0A=0AMy impression of a
utomotive fuel injection is that turning the key off=0Astops power to both
the ignition and the fuel pump(s).=C2- This leaves=0Aburnable mixture in
the cylinders and intake manifold.=C2- In an airplane,=0Athis method of s
topping the engine increases the risk of unexpected prop=0Amotion.=C2- Tu
rning the key to run causes the fuel pump(s) to run until the=0Aspecified s
ystem pressure is reached, at which point the pump(s) turn off.=0A=0AOne ot
her thing I have noticed is that some electronic ignition systems=0Amay fir
e the spark plugs one time when the system is energized.=C2- This will=0A
likely cause the prop to turn if there is a burnable mixture in the=0Acylin
ders.=C2- In fact, my Varieze has such a system.=C2- A number of times
I=0Ahave actually had the engine start spontaneously because of this effect
-=0Aprime with accelerator pump, walk the prop to pull fuel into the=0Acyl
inders, turn on the ignition, and away it goes.=C2- So, magnetos aren't
=0Athe only things that will fire unexpectedly.=C2- In fact, a mag withou
t an=0Aimpulse couple isn't likely going to spark on its own..=0A=0ASo to g
et back to the original question,=C2- I agree that stopping the fuel=0Ade
livery in some way is generally a good idea.=C2- I think turning off the
=0Apumps while leaving the ignition firing is the best bet, as that should
=0Adump fuel system pressure, and yield the least burnable mixture in the
=0Acylinders.=0A=0AWith all that said, everyone working around aircraft sho
uld be very=0Acareful of the propeller, whatever method is used to stop the
engine. =0APilots need to be vigilant to not allow anyone to haphazardly m
ove the=0Aprop or stand in the prop arc.=0A=0A=0ARegards,=0A=0AMatt-=0A=0A>
In an Aviation carb=99ed or injected engine, the shutoff method is t
he=0A> same- turn off the fuel. The reason for this is to prevent a fuel/ai
r=0A> mixture being left in a cylinder. If a P lead wire is broken and the
=0A> propeller is turned, it could fire and injure someone. From your=0A> q
uestion I assume you=99re installing an auto engine.=0A>=0A> Auto eng
ines kill the spark. Some might also kill the pressure in the=0A> fuel rail
. You=99re going to have to blas=C3=A9 your own trail here.=0A>=0A> B
ruce=0A> www.Glasair.org=0A> -----Original Message-----=0A> From: owner-aer
oelectric-list-server@matronics.com=0A> [mailto:owner-aeroelectric-list-ser
ver@matronics.com] On Behalf Of=0A> Kenneth Johnson=0A> Sent: Tuesday, Apri
l 27, 2010 12:45 PM=0A> To: aeroelectric-list@matronics.com=0A> Subject: Ae
roElectric-List: stopping engine=0A>=0A> Aircraft Electrical Gurus,=0A> Thi
s subject has been presented briefly recently, but I was looking for=0A> th
e opinion of several.=C2- This may have an electrical solution of not.=0A
> The question is: "What is the best way to stop your aircraft engine?=0A>
=0A> In the recent past, at this site I have seen recommended a switch to t
he=0A> fuel pump.=C2- Turn off the fuel pump and eventually the engine st
ops.=0A>=0A> I rent Cessna 172 and the prefered way to stop the engine is t
o minimize=0A> both the throttle and richness knobs by pulling them out.=C2
- Technically,=0A> what exactly does this do?=C2- Could I place a simpl
e ball valve on my fuel=0A> rail and phsically close it?=C2- Is this what
I do on the Cessna 172?=C2- The=0A> Cessna fuel is fed throught a carbur
etor and my engine is fuel injected.=0A> Does that make a difference?=0A>
=0A> On the automobile engine, when we turn off the engine, are we just=0A>
closing the switch that provides current to the spark plugs, or is=0A> som
ething else involved?=C2- Is this what should be done for the aircraft=0A
> engine?=0A>=0A> Thanks for your advice.=0A>=0A> Ken Johnson=0A>=0A>=0A>
-========================
=C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- -Matt
=============0A=0A=0A
Message 5
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Subject: | Re: Big load on BAT BUS |
klehman(at)albedo.net wrote:
> There are details that aren't mentioned but I would be cautious with
> this. ..snip...
>
> To understand where I am coming from, understand that the so called
> "redundant" electronic engine systems that I've examined do not come
> close to true redundancy. Most do not have dual injectors and most share
> a single feed to the injectors.
>
> Ken
>
>
Ken,
Thanks for your observations and I'm sorry for the delayed response. My ISP has
been down for awhile. It's not often that we have rain and low temps in April
in Central Calif and the wireless system antenna on a 6500' peak took a load
of ice and collapsed.
My EFI system is the quasi-redundant type that you referred to. A single ECU, injectors,
TPS, etc. I inquired about "dualing" up the system but they said that
they had tried that and that the result, because of the additional complexities,
was a far less reliable system than the single system. SDS has accumulated
15,000+ flight hours, over 12,000,000 ground ops hours and bench top set up
that has been firing away, 24/7, for years, all without a single equipment failure
that was not caused by customer wiring/installation errors. MTBF far exceeds
that of any reciprocating engine. I decided that the track record that Simple
Digital Systems has accumulated gave me sufficient confidence to run the single
system.
BUT... as long as I had multiple sources of power (2 alts, 1 bat), I wanted to
hedge my bets by connecting my single EFI to all 3, via Z-13. The Z-32 contactor
add-on will be the third power source after losing two alternators.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=296048#296048
Message 6
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Subject: | Re: stopping engine |
I have a GEO engine, EFI is the EC2 system, with 2 fuel pumps going into a
single line, then to the fuel rail. In that line is a 3 way valve that I ca
n
use to bypass the rail and spill back into the fuel tank. Turning off the
engine by starving the fuel, yet keeping the pumps running smoothly works
quite well.
On Wed, Apr 28, 2010 at 10:11 AM, Kenneth Johnson <kjohnsondds@yahoo.com>wr
ote:
> Hi All,
> I would like to thank all who responded.
>
> It would seem the best reason to stop an engine with fuel starvation woul
d
> be to prevent possible danger from the prop. If a prop was repositioned,
> fuel in a cylinder might ignite, which in turn would turn the prop and th
at
> might hurt someone. In an automobile, if dieseling occurs, no is hurt.
The
> car is in "Park" or "Neutral."
>
> I have a Mazda rotary engine I will be using for my airplane. Eventhough
> this is not a piston engine, the threat of danger from the prop with fuel
> left in the burn chamber still exists. For safety reasons, fuel starvati
on
> would be the best way to stop the engine. Turning off the ignition will
> stop current to the spark plugs, coils, and will turn off the high pressu
re
> fuel pump. However, it would seem that turning off the fuel pump before
> turning off the ignition would be a safer way to eliminate fuel from the
> burn chambers.
>
> By using a valve on my fuel rail, I could stop fuel. However, the fuel
> pump would still be working and could be damaged. Again, it would seem t
hat
> switching off the fuel pump before the ignition might be the best solutio
n.
>
>
> If anyone has a better solution, please post.
>
> Thanks,
>
> Ken Johnson
>
> ------------------------------
> *From:* Matt Prather <mprather@spro.net>
> *To:* aeroelectric-list@matronics.com
> *Sent:* Tue, April 27, 2010 1:54:43 PM
> *Subject:* RE: AeroElectric-List: stopping engine
>
t
> >
>
> I think it's worthwhile to be precise (reduce ambiguity) in matters such
> as this.
>
> I believe many (most?) light airplane POH's specify that engine shutdown
> is accomplished by moving the mixture control to idle-cutoff (ICO).
> Usually this causes the engine to stop running fairly rapidly - in a
> matter of a couple of seconds. Selecting rich mixture and hitting the
> starter usually allows the engine to restart very quickly/easily.
>
> Certainly many airplanes still have Stromberg carbs (or similar) which
> don't have a mixture control effective enough to cause "idle-cutoff". I
> have ridden with pilots of such airplanes who only use the magneto
> switches to stop the engine. One benefit of this procedure is that you
> check to see if you have a "hot mag" on each flight. If the engine stops
> dead, you can be somewhat certain that the p-lead circuit is in working
> condition.
>
> Most (all?) light airplanes also have at least one fuel control valve
> (selector), which can also be used to stop the flow of fuel to the engine
.
> On the carbureted engines that I have operated, closing this fuel valve
> does eventually stop the engine, though depending on how low the throttle
> setting is, it might take a few minutes for the float bowl in the carb to
> get low enough to cause the engine to lean-out and die. Usually when I
> pull up to a parking spot, I don't feel like waiting for the carb to
> empty, so I never do this.
>
> If the fuel valve was turned off, on carbureted airplanes with gravity
> feed fuel, turning on the fuel valve and waiting a few moments will refil
l
> the carb float bowl, at which point the engine may be restarted. For an
> airplane with pump driven fuel, turning on the electric pump will allow
> restarting much faster/sooner than if only the engine driven pump is used
.
> Turning on the electric pump is often in the engine start procedure.
>
> In an airplane that depends on a high pressure electric pump, I'm not sur
e
> it makes sense to "turn off the fuel," if that implies closing some kind
> of fuel valve. It might make more sense to turn off the electric pump(s)
.
>
> My impression of automotive fuel injection is that turning the key off
> stops power to both the ignition and the fuel pump(s). This leaves
> burnable mixture in the cylinders and intake manifold. In an airplane,
> this method of stopping the engine increases the risk of unexpected prop
> motion. Turning the key to run causes the fuel pump(s) to run until the
> specified system pressure is reached, at which point the pump(s) turn off
.
>
> One other thing I have noticed is that some electronic ignition systems
> may fire the spark plugs one time when the system is energized. This wil
l
> likely cause the prop to turn if there is a burnable mixture in the
> cylinders. In fact, my Varieze has such a system. A number of times I
> have actually had the engine start spontaneously because of this effect -
> prime with accelerator pump, walk the prop to pull fuel into the
> cylinders, turn on the ignition, and away it goes. So, magnetos aren't
> the only things that will fire unexpectedly. In fact, a mag without an
> impulse couple isn't likely going to spark on its own..
>
> So to get back to the original question, I agree that stopping the fuel
> delivery in some way is generally a good idea. I think turning off the
> pumps while leaving the ignition firing is the best bet, as that should
> dump fuel system pressure, and yield the least burnable mixture in the
> cylinders.
>
> With all that said, everyone working around aircraft should be very
> careful of the propeller, whatever method is used to stop the engine.
> Pilots need to be vigilant to not allow anyone to haphazardly move the
> prop or stand in the prop arc.
>
>
> Regards,
>
> Matt-
>
> > In an Aviation carb=92ed or injected engine, the shutoff method is the
> > same- turn off the fuel. The reason for this is to prevent a fuel/air
> > mixture being left in a cylinder. If a P lead wire is broken and the
> > propeller is turned, it could fire and injure someone. From your
> > question I assume you=92re installing an auto engine.
> >
> > Auto engines kill the spark. Some might also kill the pressure in the
> > fuel rail. You=92re going to have to blas=E9 your own trail here.
> >
> > Bruce
> > www.Glasair.org <http://www.glasair.org/>
> > -----Original Message-----
> > From: owner-aeroelectric-list-server@matronics.com
> > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> > Kenneth Johnson
> > Sent: Tuesday, April 27, 2010 12:45 PM
> > To: aeroelectric-list@matronics.com
> > Subject: AeroElectric-List: stopping engine
> >
> > Aircraft Electrical Gurus,
> > This subject has been presented briefly recently, but I was looking for
> > the opinion of several. This may have an electrical solution of not.
> > The question is: "What is the best way to stop your aircraft engine?
> >
> > In the recent past, at this site I have seen recommended a switch to th
e
> > fuel pump. Turn off the fuel pump and eventually the engine stops.
> >
> > I rent Cessna 172 and the prefered way to stop the engine is to minimiz
e
> > both the throttle and richness knobs by pulling them out. Technically,
> > what exactly does this do? Could I place a simple ball valve on my fue
l
> > rail and phsically close it? Is this what I do on the Cessna 172? The
> > Cessna fuel is fed throught a carburetor and my engine is fuel injected
.
> > Does that make a difference?
> >
> > On the automobile engine, when we turn off the engine, are we just
> > closing the switch that provides current to the spark plugs, or is
> > something else involved? Is this what should be done for the aircraft
> > engine?
> >
> > Thanks for your advice.
> >
> > Ken Johnson
> >
> >
> >
> >
>
>
> *
>
===========
===========
===========
===========
> *
>
>
--
Mike
======
Mike Fontenot
Apex Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef AT apexconsultingservices DOT com
======
Message 7
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|
Ken,
You didn=92t say if you have fuel injection or a carb on your Mazda
rotary,
but if you have FI, you can shut off the injectors and the engine will
immediately stop due to fuel starvation. No fuel will be left in the
rotor
faces. The fuel regulator will then immediately open up to keep the
fuel
pressure at your set point, so the fuel pumps will not be adversely
affected. In fact, this is the condition you will have the regulator
and
pumps in when you set the fuel pressure. This is the way it is designed
to
work so no damage will ensue. After the engine stops you can leisurely
shut
everything else down. There will be no fuel in the rotors so there will
be
no danger if you want to move the prop for whatever reason.
If you have a carb, well, you are on your own.. :>)
Bill B
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Kenneth
Johnson
Sent: Wednesday, April 28, 2010 12:11 PM
Subject: Re: AeroElectric-List: stopping engine
Hi All,
I would like to thank all who responded.
It would seem the best reason to stop an engine with fuel starvation
would
be to prevent possible danger from the prop. If a prop was
repositioned,
fuel in a cylinder might ignite, which in turn would turn the prop and
that
might hurt someone. In an automobile, if dieseling occurs, no is hurt.
The
car is in "Park" or "Neutral."
I have a Mazda rotary engine I will be using for my airplane.
Eventhough
this is not a piston engine, the threat of danger from the prop with
fuel
left in the burn chamber still exists. For safety reasons, fuel
starvation
would be the best way to stop the engine. Turning off the ignition will
stop current to the spark plugs, coils, and will turn off the high
pressure
fuel pump. However, it would seem that turning off the fuel pump before
turning off the ignition would be a safer way to eliminate fuel from the
burn chambers.
By using a valve on my fuel rail, I could stop fuel. However, the fuel
pump
would still be working and could be damaged. Again, it would seem that
switching off the fuel pump before the ignition might be the best
solution.
If anyone has a better solution, please post.
Thanks,
Ken Johnson
_____
From: Matt Prather <mprather@spro.net>
Sent: Tue, April 27, 2010 1:54:43 PM
Subject: RE: AeroElectric-List: stopping engine
<mprather@spro.net>
I think it's worthwhile to be precise (reduce ambiguity) in matters such
as this.
I believe many (most?) light airplane POH's specify that engine shutdown
is accomplished by moving the mixture control to idle-cutoff (ICO).
Usually this causes the engine to stop running fairly rapidly - in a
matter of a couple of seconds. Selecting rich mixture and hitting the
starter usually allows the engine to restart very quickly/easily.
Certainly many airplanes still have Stromberg carbs (or similar) which
don't have a mixture control effective enough to cause "idle-cutoff". I
have ridden with pilots of such airplanes who only use the magneto
switches to stop the engine. One benefit of this procedure is that you
check to see if you have a "hot mag" on each flight. If the engine
stops
dead, you can be somewhat certain that the p-lead circuit is in working
condition.
Most (all?) light airplanes also have at least one fuel control valve
(selector), which can also be used to stop the flow of fuel to the
engine.
On the carbureted engines that I have operated, closing this fuel valve
does eventually stop the engine, though depending on how low the
throttle
setting is, it might take a few minutes for the float bowl in the carb
to
get low enough to cause the engine to lean-out and die. Usually when I
pull up to a parking spot, I don't feel like waiting for the carb to
empty, so I never do this.
If the fuel valve was turned off, on carbureted airplanes with gravity
feed fuel, turning on the fuel valve and waiting a few moments will
refill
the carb float bowl, at which point the engine may be restarted. For an
airplane with pump driven fuel, turning on the electric pump will allow
restarting much faster/sooner than if only the engine driven pump is
used.
Turning on the electric pump is often in the engine start procedure.
In an airplane that depends on a high pressure electric pump, I'm not
sure
it makes sense to "turn off the fuel," if that implies closing some kind
of fuel valve. It might make more sense to turn off the electric
pump(s).
My impression of automotive fuel injection is that turning the key off
stops power to both the ignition and the fuel pump(s). This leaves
burnable mixture in the cylinders and intake manifold. In an airplane,
this method of stopping the engine increases the risk of unexpected prop
motion. Turning the key to run causes the fuel pump(s) to run until the
specified system pressure is reached, at which point the pump(s) turn
off.
One other thing I have noticed is that some electronic ignition systems
may fire the spark plugs one time when the system is energized. This
will
likely cause the prop to turn if there is a burnable mixture in the
cylinders. In fact, my Varieze has such a system. A number of times I
have actually had the engine start spontaneously because of this effect
-
prime with accelerator pump, walk the prop to pull fuel into the
cylinders, turn on the ignition, and away it goes. So, magnetos aren't
the only things that will fire unexpectedly. In fact, a mag without an
impulse couple isn't likely going to spark on its own..
So to get back to the original question, I agree that stopping the fuel
delivery in some way is generally a good idea. I think turning off the
pumps while leaving the ignition firing is the best bet, as that should
dump fuel system pressure, and yield the least burnable mixture in the
cylinders.
With all that said, everyone working around aircraft should be very
careful of the propeller, whatever method is used to stop the engine.
Pilots need to be vigilant to not allow anyone to haphazardly move the
prop or stand in the prop arc.
Regards,
Matt-
> In an Aviation carb=92ed or injected engine, the shutoff method is the
> same- turn off the fuel. The reason for this is to prevent a fuel/air
> mixture being left in a cylinder. If a P lead wire is broken and the
> propeller is turned, it could fire and injure someone. From your
> question I assume you=92re installing an auto engine.
>
> Auto engines kill the spark. Some might also kill the pressure in the
> fuel rail. You=92re going to have to blas=E9 your own trail here.
>
> Bruce
> www.Glasair.org <http://www.glasair.org/>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> Kenneth Johnson
> Sent: Tuesday, April 27, 2010 12:45 PM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: stopping engine
>
> Aircraft Electrical Gurus,
> This subject has been presented briefly recently, but I was looking
for
> the opinion of several. This may have an electrical solution of not.
> The question is: "What is the best way to stop your aircraft engine?
>
> In the recent past, at this site I have seen recommended a switch to
the
> fuel pump. Turn off the fuel pump and eventually the engine stops.
>
> I rent Cessna 172 and the prefered way to stop the engine is to
minimize
> both the throttle and richness knobs by pulling them out.
Technically,
> what exactly does this do? Could I place a simple ball valve on my
fuel
> rail and phsically close it? Is this what I do on the Cessna 172?
The
> Cessna fuel is fed throught a carburetor and my engine is fuel
injected.
> Does that make a difference?
>
> On the automobile engine, when we turn off the engine, are we just
> closing the switch that provides current to the spark plugs, or is
> something else involved? Is this what should be done for the aircraft
> engine?
>
> Thanks for your advice.
>
> Ken Johnson
>
>
><B -Matt=============
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Ken,
If you are building a Mazda rotary for your plane you should really look
into the rotary forum. There is a tremendous amount of knowledge
available
there. Come join us!
http://mail.lancaironline.net:81/lists/flyrotary/List.html
How to subscribe is at the lower right corner.
Bill B
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Kenneth
Johnson
Sent: Wednesday, April 28, 2010 12:11 PM
Subject: Re: AeroElectric-List: stopping engine
Hi All,
I would like to thank all who responded.
It would seem the best reason to stop an engine with fuel starvation
would
be to prevent possible danger from the prop. If a prop was
repositioned,
fuel in a cylinder might ignite, which in turn would turn the prop and
that
might hurt someone. In an automobile, if dieseling occurs, no is hurt.
The
car is in "Park" or "Neutral."
I have a Mazda rotary engine I will be using for my airplane.
Eventhough
this is not a piston engine, the threat of danger from the prop with
fuel
left in the burn chamber still exists. For safety reasons, fuel
starvation
would be the best way to stop the engine. Turning off the ignition will
stop current to the spark plugs, coils, and will turn off the high
pressure
fuel pump. However, it would seem that turning off the fuel pump before
turning off the ignition would be a safer way to eliminate fuel from the
burn chambers.
By using a valve on my fuel rail, I could stop fuel. However, the fuel
pump
would still be working and could be damaged. Again, it would seem that
switching off the fuel pump before the ignition might be the best
solution.
If anyone has a better solution, please post.
Thanks,
Ken Johnson
_____
From: Matt Prather <mprather@spro.net>
Sent: Tue, April 27, 2010 1:54:43 PM
Subject: RE: AeroElectric-List: stopping engine
<mprather@spro.net>
I think it's worthwhile to be precise (reduce ambiguity) in matters such
as this.
I believe many (most?) light airplane POH's specify that engine shutdown
is accomplished by moving the mixture control to idle-cutoff (ICO).
Usually this causes the engine to stop running fairly rapidly - in a
matter of a couple of seconds. Selecting rich mixture and hitting the
starter usually allows the engine to restart very quickly/easily.
Certainly many airplanes still have Stromberg carbs (or similar) which
don't have a mixture control effective enough to cause "idle-cutoff". I
have ridden with pilots of such airplanes who only use the magneto
switches to stop the engine. One benefit of this procedure is that you
check to see if you have a "hot mag" on each flight. If the engine
stops
dead, you can be somewhat certain that the p-lead circuit is in working
condition.
Most (all?) light airplanes also have at least one fuel control valve
(selector), which can also be used to stop the flow of fuel to the
engine.
On the carbureted engines that I have operated, closing this fuel valve
does eventually stop the engine, though depending on how low the
throttle
setting is, it might take a few minutes for the float bowl in the carb
to
get low enough to cause the engine to lean-out and die. Usually when I
pull up to a parking spot, I don't feel like waiting for the carb to
empty, so I never do this.
If the fuel valve was turned off, on carbureted airplanes with gravity
feed fuel, turning on the fuel valve and waiting a few moments will
refill
the carb float bowl, at which point the engine may be restarted. For an
airplane with pump driven fuel, turning on the electric pump will allow
restarting much faster/sooner than if only the engine driven pump is
used.
Turning on the electric pump is often in the engine start procedure.
In an airplane that depends on a high pressure electric pump, I'm not
sure
it makes sense to "turn off the fuel," if that implies closing some kind
of fuel valve. It might make more sense to turn off the electric
pump(s).
My impression of automotive fuel injection is that turning the key off
stops power to both the ignition and the fuel pump(s). This leaves
burnable mixture in the cylinders and intake manifold. In an airplane,
this method of stopping the engine increases the risk of unexpected prop
motion. Turning the key to run causes the fuel pump(s) to run until the
specified system pressure is reached, at which point the pump(s) turn
off.
One other thing I have noticed is that some electronic ignition systems
may fire the spark plugs one time when the system is energized. This
will
likely cause the prop to turn if there is a burnable mixture in the
cylinders. In fact, my Varieze has such a system. A number of times I
have actually had the engine start spontaneously because of this effect
-
prime with accelerator pump, walk the prop to pull fuel into the
cylinders, turn on the ignition, and away it goes. So, magnetos aren't
the only things that will fire unexpectedly. In fact, a mag without an
impulse couple isn't likely going to spark on its own..
So to get back to the original question, I agree that stopping the fuel
delivery in some way is generally a good idea. I think turning off the
pumps while leaving the ignition firing is the best bet, as that should
dump fuel system pressure, and yield the least burnable mixture in the
cylinders.
With all that said, everyone working around aircraft should be very
careful of the propeller, whatever method is used to stop the engine.
Pilots need to be vigilant to not allow anyone to haphazardly move the
prop or stand in the prop arc.
Regards,
Matt-
> In an Aviation carb=92ed or injected engine, the shutoff method is the
> same- turn off the fuel. The reason for this is to prevent a fuel/air
> mixture being left in a cylinder. If a P lead wire is broken and the
> propeller is turned, it could fire and injure someone. From your
> question I assume you=92re installing an auto engine.
>
> Auto engines kill the spark. Some might also kill the pressure in the
> fuel rail. You=92re going to have to blas=E9 your own trail here.
>
> Bruce
> www.Glasair.org <http://www.glasair.org/>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> Kenneth Johnson
> Sent: Tuesday, April 27, 2010 12:45 PM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: stopping engine
>
> Aircraft Electrical Gurus,
> This subject has been presented briefly recently, but I was looking
for
> the opinion of several. This may have an electrical solution of not.
> The question is: "What is the best way to stop your aircraft engine?
>
> In the recent past, at this site I have seen recommended a switch to
the
> fuel pump. Turn off the fuel pump and eventually the engine stops.
>
> I rent Cessna 172 and the prefered way to stop the engine is to
minimize
> both the throttle and richness knobs by pulling them out.
Technically,
> what exactly does this do? Could I place a simple ball valve on my
fuel
> rail and phsically close it? Is this what I do on the Cessna 172?
The
> Cessna fuel is fed throught a carburetor and my engine is fuel
injected.
> Does that make a difference?
>
> On the automobile engine, when we turn off the engine, are we just
> closing the switch that provides current to the spark plugs, or is
> something else involved? Is this what should be done for the aircraft
> engine?
>
> Thanks for your advice.
>
> Ken Johnson
>
>
><B -Matt=============
Message 9
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|
Bill,
My only concern about this (and it's probably a remote concern) is that if
you have a leaking injector, it may dribble fuel into the engine after
shutdown. Otherwise, this is very much analogous to pulling the mixture
to ICO on an aircraft carb or mechanical injection.
Matt-
> Ken,
>
> You didnt say if you have fuel injection or a carb on your Mazda rotary,
> but if you have FI, you can shut off the injectors and the engine will
> immediately stop due to fuel starvation. No fuel will be left in the
> rotor
> faces. The fuel regulator will then immediately open up to keep the fuel
> pressure at your set point, so the fuel pumps will not be adversely
> affected. In fact, this is the condition you will have the regulator and
> pumps in when you set the fuel pressure. This is the way it is designed
> to
> work so no damage will ensue. After the engine stops you can leisurely
> shut
> everything else down. There will be no fuel in the rotors so there will
> be
> no danger if you want to move the prop for whatever reason.
>
> If you have a carb, well, you are on your own.. :>)
>
>
> Bill B
>
>
> _____
>
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kenneth
> Johnson
> Sent: Wednesday, April 28, 2010 12:11 PM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: stopping engine
>
>
> Hi All,
>
> I would like to thank all who responded.
>
>
> It would seem the best reason to stop an engine with fuel starvation would
> be to prevent possible danger from the prop. If a prop was repositioned,
> fuel in a cylinder might ignite, which in turn would turn the prop and
> that
> might hurt someone. In an automobile, if dieseling occurs, no is hurt.
> The
> car is in "Park" or "Neutral."
>
>
> I have a Mazda rotary engine I will be using for my airplane. Eventhough
> this is not a piston engine, the threat of danger from the prop with fuel
> left in the burn chamber still exists. For safety reasons, fuel
> starvation
> would be the best way to stop the engine. Turning off the ignition will
> stop current to the spark plugs, coils, and will turn off the high
> pressure
> fuel pump. However, it would seem that turning off the fuel pump before
> turning off the ignition would be a safer way to eliminate fuel from the
> burn chambers.
>
>
> By using a valve on my fuel rail, I could stop fuel. However, the fuel
> pump
> would still be working and could be damaged. Again, it would seem that
> switching off the fuel pump before the ignition might be the best
> solution.
>
>
> If anyone has a better solution, please post.
>
>
> Thanks,
>
>
> Ken Johnson
>
>
> _____
>
> From: Matt Prather <mprather@spro.net>
> To: aeroelectric-list@matronics.com
> Sent: Tue, April 27, 2010 1:54:43 PM
> Subject: RE: AeroElectric-List: stopping engine
>
> <mprather@spro.net>
>
> I think it's worthwhile to be precise (reduce ambiguity) in matters such
> as this.
>
> I believe many (most?) light airplane POH's specify that engine shutdown
> is accomplished by moving the mixture control to idle-cutoff (ICO).
> Usually this causes the engine to stop running fairly rapidly - in a
> matter of a couple of seconds. Selecting rich mixture and hitting the
> starter usually allows the engine to restart very quickly/easily.
>
> Certainly many airplanes still have Stromberg carbs (or similar) which
> don't have a mixture control effective enough to cause "idle-cutoff". I
> have ridden with pilots of such airplanes who only use the magneto
> switches to stop the engine. One benefit of this procedure is that you
> check to see if you have a "hot mag" on each flight. If the engine stops
> dead, you can be somewhat certain that the p-lead circuit is in working
> condition.
>
> Most (all?) light airplanes also have at least one fuel control valve
> (selector), which can also be used to stop the flow of fuel to the engine.
> On the carbureted engines that I have operated, closing this fuel valve
> does eventually stop the engine, though depending on how low the throttle
> setting is, it might take a few minutes for the float bowl in the carb to
> get low enough to cause the engine to lean-out and die. Usually when I
> pull up to a parking spot, I don't feel like waiting for the carb to
> empty, so I never do this.
>
> If the fuel valve was turned off, on carbureted airplanes with gravity
> feed fuel, turning on the fuel valve and waiting a few moments will refill
> the carb float bowl, at which point the engine may be restarted. For an
> airplane with pump driven fuel, turning on the electric pump will allow
> restarting much faster/sooner than if only the engine driven pump is used.
> Turning on the electric pump is often in the engine start procedure.
>
> In an airplane that depends on a high pressure electric pump, I'm not sure
> it makes sense to "turn off the fuel," if that implies closing some kind
> of fuel valve. It might make more sense to turn off the electric pump(s).
>
> My impression of automotive fuel injection is that turning the key off
> stops power to both the ignition and the fuel pump(s). This leaves
> burnable mixture in the cylinders and intake manifold. In an airplane,
> this method of stopping the engine increases the risk of unexpected prop
> motion. Turning the key to run causes the fuel pump(s) to run until the
> specified system pressure is reached, at which point the pump(s) turn off.
>
> One other thing I have noticed is that some electronic ignition systems
> may fire the spark plugs one time when the system is energized. This will
> likely cause the prop to turn if there is a burnable mixture in the
> cylinders. In fact, my Varieze has such a system. A number of times I
> have actually had the engine start spontaneously because of this effect -
> prime with accelerator pump, walk the prop to pull fuel into the
> cylinders, turn on the ignition, and away it goes. So, magnetos aren't
> the only things that will fire unexpectedly. In fact, a mag without an
> impulse couple isn't likely going to spark on its own..
>
> So to get back to the original question, I agree that stopping the fuel
> delivery in some way is generally a good idea. I think turning off the
> pumps while leaving the ignition firing is the best bet, as that should
> dump fuel system pressure, and yield the least burnable mixture in the
> cylinders.
>
> With all that said, everyone working around aircraft should be very
> careful of the propeller, whatever method is used to stop the engine.
> Pilots need to be vigilant to not allow anyone to haphazardly move the
> prop or stand in the prop arc.
>
>
> Regards,
>
> Matt-
>
>> In an Aviation carbed or injected engine, the shutoff method is the
>> same- turn off the fuel. The reason for this is to prevent a fuel/air
>> mixture being left in a cylinder. If a P lead wire is broken and the
>> propeller is turned, it could fire and injure someone. From your
>> question I assume youre installing an auto engine.
>>
>> Auto engines kill the spark. Some might also kill the pressure in the
>> fuel rail. Youre going to have to blas your own trail here.
>>
>> Bruce
>> www.Glasair.org <http://www.glasair.org/>
>> -----Original Message-----
>> From: owner-aeroelectric-list-server@matronics.com
>> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
>> Kenneth Johnson
>> Sent: Tuesday, April 27, 2010 12:45 PM
>> To: aeroelectric-list@matronics.com
>> Subject: AeroElectric-List: stopping engine
>>
>> Aircraft Electrical Gurus,
>> This subject has been presented briefly recently, but I was looking for
>> the opinion of several. This may have an electrical solution of not.
>> The question is: "What is the best way to stop your aircraft engine?
>>
>> In the recent past, at this site I have seen recommended a switch to the
>> fuel pump. Turn off the fuel pump and eventually the engine stops.
>>
>> I rent Cessna 172 and the prefered way to stop the engine is to minimize
>> both the throttle and richness knobs by pulling them out. Technically,
>> what exactly does this do? Could I place a simple ball valve on my fuel
>> rail and phsically close it? Is this what I do on the Cessna 172? The
>> Cessna fuel is fed throught a carburetor and my engine is fuel injected.
>> Does that make a difference?
>>
>> On the automobile engine, when we turn off the engine, are we just
>> closing the switch that provides current to the spark plugs, or is
>> something else involved? Is this what should be done for the aircraft
>> engine?
>>
>> Thanks for your advice.
>>
>> Ken Johnson
>>
>>
>>
>><B -Matt=============
>
>
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Subject: | Electrical diagram |
Was wondering if you guys could have a look at this diagram and tell me what you
think. It is a variation of Z-11. A couple of things about the design. Aircraft
will be flown IMC. Two EFIS panels with internal battery backup. The
alternator is a Plane Power with internal regulator and crowbar over voltage protection.
I talked to the engineers at Plane Power and they told me that that
alternator would function just fine if the battery were hypothetically removed
from the aircraft while it was running, hence no off-batt-gen switch. The
start enable switch will be guarded and is an added safety item to the push button
start. I have tried to consider as many failure modes as possible but am
not nearly as savvy as many on this forum. Thanks in advance for inputs.
Marc
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=296088#296088
Attachments:
http://forums.matronics.com//files/elec_schematic11_667.jpg
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|
Subject: | Re: stopping engine |
I have Mazda Rotary with EC-2 and electric fuel pump. shut down consists
of shutting off the fuel pump, engine dies quickly, and there is no
residual pressure in the lines to leak past the injectors and cause
flooding or richness on the start.
Bill Schertz
KIS Cruiser #4045
N343BS
Phase I testing
From: Bill Bradburry
Sent: Wednesday, April 28, 2010 12:09 PM
Subject: RE: AeroElectric-List: stopping engine
Ken,
You didn't say if you have fuel injection or a carb on your Mazda
rotary, but if you have FI, you can shut off the injectors and the
engine will immediately stop due to fuel starvation. No fuel will be
left in the rotor faces. The fuel regulator will then immediately open
up to keep the fuel pressure at your set point, so the fuel pumps will
not be adversely affected. In fact, this is the condition you will have
the regulator and pumps in when you set the fuel pressure. This is the
way it is designed to work so no damage will ensue. After the engine
stops you can leisurely shut everything else down. There will be no
fuel in the rotors so there will be no danger if you want to move the
prop for whatever reason.
If you have a carb, well, you are on your own.. :>)
Bill B
-------------------------------------------------------------------------
-------
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Kenneth Johnson
Sent: Wednesday, April 28, 2010 12:11 PM
Subject: Re: AeroElectric-List: stopping engine
Hi All,
I would like to thank all who responded.
It would seem the best reason to stop an engine with fuel starvation
would be to prevent possible danger from the prop. If a prop was
repositioned, fuel in a cylinder might ignite, which in turn would turn
the prop and that might hurt someone. In an automobile, if dieseling
occurs, no is hurt. The car is in "Park" or "Neutral."
I have a Mazda rotary engine I will be using for my airplane.
Eventhough this is not a piston engine, the threat of danger from the
prop with fuel left in the burn chamber still exists. For safety
reasons, fuel starvation would be the best way to stop the engine.
Turning off the ignition will stop current to the spark plugs, coils,
and will turn off the high pressure fuel pump. However, it would seem
that turning off the fuel pump before turning off the ignition would be
a safer way to eliminate fuel from the burn chambers.
By using a valve on my fuel rail, I could stop fuel. However, the fuel
pump would still be working and could be damaged. Again, it would seem
that switching off the fuel pump before the ignition might be the best
solution.
If anyone has a better solution, please post.
Thanks,
Ken Johnson
-------------------------------------------------------------------------
-------
From: Matt Prather <mprather@spro.net>
Sent: Tue, April 27, 2010 1:54:43 PM
Subject: RE: AeroElectric-List: stopping engine
<mprather@spro.net>
I think it's worthwhile to be precise (reduce ambiguity) in matters such
as this.
I believe many (most?) light airplane POH's specify that engine shutdown
is accomplished by moving the mixture control to idle-cutoff (ICO).
Usually this causes the engine to stop running fairly rapidly - in a
matter of a couple of seconds. Selecting rich mixture and hitting the
starter usually allows the engine to restart very quickly/easily.
Certainly many airplanes still have Stromberg carbs (or similar) which
don't have a mixture control effective enough to cause "idle-cutoff". I
have ridden with pilots of such airplanes who only use the magneto
switches to stop the engine. One benefit of this procedure is that you
check to see if you have a "hot mag" on each flight. If the engine
stops
dead, you can be somewhat certain that the p-lead circuit is in working
condition.
Most (all?) light airplanes also have at least one fuel control valve
(selector), which can also be used to stop the flow of fuel to the
engine.
On the carbureted engines that I have operated, closing this fuel valve
does eventually stop the engine, though depending on how low the
throttle
setting is, it might take a few minutes for the float bowl in the carb
to
get low enough to cause the engine to lean-out and die. Usually when I
pull up to a parking spot, I don't feel like waiting for the carb to
empty, so I never do this.
If the fuel valve was turned off, on carbureted airplanes with gravity
feed fuel, turning on the fuel valve and waiting a few moments will
refill
the carb float bowl, at which point the engine may be restarted. For an
airplane with pump driven fuel, turning on the electric pump will allow
restarting much faster/sooner than if only the engine driven pump is
used.
Turning on the electric pump is often in the engine start procedure.
In an airplane that depends on a high pressure electric pump, I'm not
sure
it makes sense to "turn off the fuel," if that implies closing some kind
of fuel valve. It might make more sense to turn off the electric
pump(s).
My impression of automotive fuel injection is that turning the key off
stops power to both the ignition and the fuel pump(s). This leaves
burnable mixture in the cylinders and intake manifold. In an airplane,
this method of stopping the engine increases the risk of unexpected prop
motion. Turning the key to run causes the fuel pump(s) to run until the
specified system pressure is reached, at which point the pump(s) turn
off.
One other thing I have noticed is that some electronic ignition systems
may fire the spark plugs one time when the system is energized. This
will
likely cause the prop to turn if there is a burnable mixture in the
cylinders. In fact, my Varieze has such a system. A number of times I
have actually had the engine start spontaneously because of this effect
-
prime with accelerator pump, walk the prop to pull fuel into the
cylinders, turn on the ignition, and away it goes. So, magnetos aren't
the only things that will fire unexpectedly. In fact, a mag without an
impulse couple isn't likely going to spark on its own..
So to get back to the original question, I agree that stopping the fuel
delivery in some way is generally a good idea. I think turning off the
pumps while leaving the ignition firing is the best bet, as that should
dump fuel system pressure, and yield the least burnable mixture in the
cylinders.
With all that said, everyone working around aircraft should be very
careful of the propeller, whatever method is used to stop the engine.
Pilots need to be vigilant to not allow anyone to haphazardly move the
prop or stand in the prop arc.
Regards,
Matt-
> In an Aviation carb'ed or injected engine, the shutoff method is the
> same- turn off the fuel. The reason for this is to prevent a fuel/air
> mixture being left in a cylinder. If a P lead wire is broken and the
> propeller is turned, it could fire and injure someone. From your
> question I assume you're installing an auto engine.
>
> Auto engines kill the spark. Some might also kill the pressure in the
> fuel rail. You're going to have to blas=E9 your own trail here.
>
> Bruce
> www.Glasair.org
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> Kenneth Johnson
> Sent: Tuesday, April 27, 2010 12:45 PM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: stopping engine
>
> Aircraft Electrical Gurus,
> This subject has been presented briefly recently, but I was looking
for
> the opinion of several. This may have an electrical solution of not.
> The question is: "What is the best way to stop your aircraft engine?
>
> In the recent past, at this site I have seen recommended a switch to
the
> fuel pump. Turn off the fuel pump and eventually the engine stops.
>
> I rent Cessna 172 and the prefered way to stop the engine is to
minimize
> both the throttle and richness knobs by pulling them out.
Technically,
> what exactly does this do? Could I place a simple ball valve on my
fuel
> rail and phsically close it? Is this what I do on the Cessna 172?
The
> Cessna fuel is fed throught a carburetor and my engine is fuel
injected.
> Does that make a difference?
>
> On the automobile engine, when we turn off the engine, are we just
> closing the switch that provides current to the spark plugs, or is
> something else involved? Is this what should be done for the aircraft
> engine?
>
> Thanks for your advice.
>
> Ken Johnson
>
>
><B -Matt=============
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Message 12
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Subject: | Re: One or Two batteries with Single Alternator for |
Electric Airplane
At 08:50 AM 4/28/2010, you wrote:
>Bob,
>
>Which architecture should I be using for a VFR, day/night, single
>engine dual LSE ignition, single B&C 30 amp alternator and single
>MGL EFIS, radio, transponder, intercom?
>
>My emergency power draw would be 6.7 amps (cruise is 12.34 amps). I
>could use a single battery but would like to have a second smaller
>5-7 amp battery as a backup for the EFIS and one of the LSE ignitions.
Consider Z-13/8 with one 17 a.h. battery. Does
B&C offer a 30A alternator? LSE recommends two
batteries for two ignitions. It's a higher cost
of ownership and heavier system but it will perform
as advertised.
Bob . . .
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