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2-10 SWITCH - Can this be done?

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Sam

Joined: 18 May 2008
Posts: 135

Posted: Sun Nov 23, 2008 5:02 pm Post subject: 2-10 SWITCH - Can this be done?

I am trying to configure a switch and am currently stumped.



I have two possible power inputs A or B.



I have two possible devices, C or D.



I want the three position switch to have the following conditions, with no other combinations.

 

A powers C

B powers D

Off



Do you think this is possible with a single 2-10 Switch?  I sure couldn't figure it out.  How else might I be able to accomplish it with only one switch?  Maybe a 4-10 (and where would I get one)?

  	  Quote: 	
		  	
This all has to do with redundant power inputs providing power to two sets of fuel injectors.



Thanks,



Sam

  [quote][b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Sun Nov 23, 2008 5:31 pm Post subject: 2-10 SWITCH - Can this be done?

Sam,

 Can the center position be 'OFF'?

  

 If so, a double pole/double throw switch will work  if you use it to only switch the positive leads and use a common for the  negative for both connections. One pole, with throw in one direction, (say  up) could give you the A power to C and the other pole with the other direction  throw (say down) would give you B power to D.

  

 Dale Ensing

 [quote]   ---

_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

mrspudandcompany(at)veriz
Guest

Posted: Sun Nov 23, 2008 5:43 pm Post subject: 2-10 SWITCH - Can this be done?

I am trying to configure a switch and am currently stumped.

 

 I have two possible power inputs A or B.

 

 I have two possible devices, C or D.

 

 I want the three position switch to have the following conditions, with no other combinations.

 

 A powers C

 B powers D

 Off

 

 Do you think this is possible with a single 2-10 Switch?  I sure couldn't figure it out.  How else might I be able to accomplish it with only one switch?  Maybe a 4-10 (and where would I get one)?  

This all has to do with redundant power inputs providing power to two sets of fuel injectors.

 

 Thanks,

 

 Sam  [quote] You can accomplish this using a 2-10 switch connected as follows: A to 2, B to 5, C to 1, D to 6. A simple dpdt center off switch can be also wired for this circuit. Roger[b]

ceengland(at)bellsouth.ne
Guest

Posted: Sun Nov 23, 2008 6:28 pm Post subject: 2-10 SWITCH - Can this be done?

ROGER & JEAN CURTIS wrote:

 	  Quote: 	
		  

 I am trying to configure a switch and am currently stumped.



 I have two possible power inputs A or B.



 I have two possible devices, C or D.



 I want the three position switch to have the following conditions, 

 with no other combinations.



 A powers C

 B powers D

 Off



 Do you think this is possible with a single 2-10 Switch?  I sure 

 couldn't figure it out.  How else might I be able to accomplish it 

 with only one switch?  Maybe a 4-10 (and where would I get one)?



 This all has to do with redundant power inputs providing power to two 

 sets of fuel injectors.



 Thanks,



 Sam



 * *

 *You can accomplish this using a 2-10 switch connected as follows: A to 2, B to 5, C to 1, D to 6.*

 * *

 *A simple dpdt center off switch can be also wired for this circuit.*

 * *

 *Roger*


	


Is it acceptable that one switch failure takes out both systems?

klehman(at)albedo.net
Guest

Posted: Sun Nov 23, 2008 6:37 pm Post subject: 2-10 SWITCH - Can this be done?

I never understood why guys like this sort of thing. It means you do NOT 

have redundant systems since one switch failure can fail both sources of 

power.



FWIW my engine continues to run if I energize both injection systems and 

feed twice the normal fuel to it. Definitely rich but not a show stopper.



Ken



Sam Hoskins wrote:

 	  Quote: 	
		   I am trying to configure a switch and am currently stumped.

 

 I have two possible power inputs A or B.

 

 I have two possible devices, C or D.

 

 I want the three position switch to have the following conditions, with 

 no other combinations.

 

 A powers C

 B powers D

 Off

 

 Do you think this is possible with a single 2-10 Switch?  I sure 

 couldn't figure it out.  How else might I be able to accomplish it with 

 only one switch?  Maybe a 4-10 (and where would I get one)?

 

 This all has to do with redundant power inputs providing power to two 

 sets of fuel injectors.

 

 Thanks,

 

 Sam

nuckolls.bob(at)cox.net
Guest

Posted: Mon Nov 24, 2008 5:51 am Post subject: 2-10 SWITCH - Can this be done?

At 08:41 PM 11/23/2008, you wrote:

 	  Quote: 	

I never understood why guys like this sort of thing. It means you do 

NOT have redundant systems since one switch failure can fail both 

sources of power.

FWIW my engine continues to run if I energize both injection systems 

and feed twice the normal fuel to it. Definitely rich but not a show stopper.

Ken

   It is a product of design goals that do not consider every

   single component's vulnerability to failure. In the certified

   side of the house, we like to fill spread sheets with lots

   of calculations derived from failure rate numbers that are

   too often assumed and combinations that are too seldom

   confirmed for reliability. The final insult comes when all

   potential consequences for failure have not been mitigated

   even when a backup for the failed part exists. Remember

   Apollo 13? Somebody cranked the numbers on that thermostat

   and was "comfortable" with the probability of failure. Shucks,

   the vehicle had a service life of less than 1000 hours. Just

   how good does it need to be? Oh yeah, if it DOES croak . . .

   can I live with getting my tail blasted off?

   I will suggest that the term "redundant" is most useful when

   Plan-A has no components in common with Plan-B. The icing

   on the cake comes from consideration of the consequences of

   any single failure . . . the "best" failures do not propagate

   their effects beyond a need to replace the failed part after

   a comfortable termination of flight has been accomplished.

   Sam, the best advice we can give you is to craft your redundant

   systems with as much electrical isolation as possible/practical.

   This would include separate control switches for each set of

   injectors.

   Bob . . .

 	  Quote: 	
		  Sam Hoskins wrote:

>I am trying to configure a switch and am currently stumped.

>I have two possible power inputs A or B.

>I have two possible devices, C or D.

>I want the three position switch to have the following conditions, 

>with no other combinations.

>A powers C

>B powers D

>Off

>Do you think this is possible with a single 2-10 Switch?  I sure 

>couldn't figure it out.  How else might I be able to accomplish it 

>with only one switch?  Maybe a 4-10 (and where would I get one)?

>This all has to do with redundant power inputs providing power to 

>two sets of fuel injectors.

>Thanks,

>Sam

Sam

Joined: 18 May 2008
Posts: 135

Posted: Mon Nov 24, 2008 6:56 am Post subject: 2-10 SWITCH - Can this be done?

Thanks, Bob, et al.



This project could be held up as a textbook example of the laws of unintended consequences.



The initial project Goal:  Make an already flying plane go faster and more efficient.

 The method:  Aerodynamic clean up and addition of Electronic Fuel Injection.

The consequence:  The project stretching out over a year, with many items not on the original list, and worst, a not insignificant gain in weight - in direct opposition to The Goal.

 



I have a wire count well over one hundred, 16 switches to control power and fuel, and require in the neighborhood of 20 amps to feed endurance loads!  I am using a version of Z19/RB.  I have pretty much run out of real estate for the switch grouping. 	  Quote: 	
		   	
That is why I am trying to include the A power source and B power source with one switch.



There are lots of asides to this story, but the project really has been fun.  I'll mull all this over and see if I can find room for another #(at)$*% switch.

 

FWIW, here is my current power distribution:

http://www.mistakeproofing.net/transfer/N202SH_POWER_DISTRIBUTION_07.pdf



And the wire page for the coils and injectors:

 http://www.mistakeproofing.net/transfer/injectors_and_coils.pdf



And the load analysis:

http://www.mistakeproofing.net/transfer/Load_analysis.pdf

 

Regards,



Sam

www.samhoskins.blogspot.com



On Mon, Nov 24, 2008 at 7:49 AM, Robert L. Nuckolls, III <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

 [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> 

 

 At 08:41 PM 11/23/2008, you wrote:

  	  Quote: 	
		   --> AeroElectric-List message posted by: Ken <klehman(at)albedo.net (klehman(at)albedo.net)>

 

 I never understood why guys like this sort of thing. It means you do NOT have redundant systems since one switch failure can fail both sources of power.

 

 FWIW my engine continues to run if I energize both injection systems and feed twice the normal fuel to it. Definitely rich but not a show stopper.

 

 Ken

 	
 



   It is a product of design goals that do not consider every

   single component's vulnerability to failure. In the certified

   side of the house, we like to fill spread sheets with lots

   of calculations derived from failure rate numbers that are

   too often assumed and combinations that are too seldom

   confirmed for reliability. The final insult comes when all

   potential consequences for failure have not been mitigated

   even when a backup for the failed part exists. Remember

   Apollo 13? Somebody cranked the numbers on that thermostat

   and was "comfortable" with the probability of failure. Shucks,

   the vehicle had a service life of less than 1000 hours. Just

   how good does it need to be? Oh yeah, if it DOES croak . . .

   can I live with getting my tail blasted off?

 

   I will suggest that the term "redundant" is most useful when

   Plan-A has no components in common with Plan-B. The icing

   on the cake comes from consideration of the consequences of

   any single failure . . . the "best" failures do not propagate

   their effects beyond a need to replace the failed part after

   a comfortable termination of flight has been accomplished.

 

   Sam, the best advice we can give you is to craft your redundant

   systems with as much electrical isolation as possible/practical.

   This would include separate control switches for each set of

   injectors.

 

   Bob . . .



 

 

  	  Quote: 	
		   Sam Hoskins wrote:

  	  Quote: 	
		   I am trying to configure a switch and am currently stumped.

 I have two possible power inputs A or B.

 I have two possible devices, C or D.

 I want the three position switch to have the following conditions, with no other combinations.

 A powers C

 B powers D

 Off

 Do you think this is possible with a single 2-10 Switch?  I sure couldn't figure it out.  How else might I be able to accomplish it with only one switch?  Maybe a 4-10 (and where would I get one)?

 This all has to do with redundant power inputs providing power to two sets of fuel injectors.

 Thanks,

 Sam

 	
	
 

 

 

 

 

 



[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

nuckolls.bob(at)cox.net
Guest

Posted: Mon Nov 24, 2008 8:25 am Post subject: 2-10 SWITCH - Can this be done?

At 08:52 AM 11/24/2008, you wrote:

 	  Quote: 	
		  Thanks, Bob, et al.



This project could be held up as a textbook example of the laws of 

unintended consequences.



The initial project Goal:  Make an already flying plane go faster 

and more efficient.

The method:  Aerodynamic clean up and addition of Electronic Fuel Injection.

The consequence:  The project stretching out over a year, with many 

items not on the original list, and worst, a not insignificant gain 

in weight - in direct opposition to The Goal.



I have a wire count well over one hundred, 16 switches to control 

power and fuel, and require in the neighborhood of 20 amps to feed 

endurance loads!  I am using a version of Z19/RB.  I have pretty 

much run out of real estate for the switch grouping.



That is why I am trying to include the A power source and B power 

source with one switch.



There are lots of asides to this story, but the project really has 

been fun.  I'll mull all this over and see if I can find room for 

another #(at)$*% switch.



FWIW, here is my current power distribution:

<http://www.mistakeproofing.net/transfer/N202SH_POWER_DISTRIBUTION_07.pdf>http://www.mistakeproofing.net/transfer/N202SH_POWER_DISTRIBUTION_07.pdf



And the wire page for the coils and injectors:

<http://www.mistakeproofing.net/transfer/injectors_and_coils.pdf>http://www.mistakeproofing.net/transfer/injectors_and_coils.pdf



And the load analysis:

<http://www.mistakeproofing.net/transfer/Load_analysis.pdf>http://www.mistakeproofing.net/transfer/Load_analysis.pdf


	


   It's not clear how you ended up with so many switches. It's

   axiomatic that the more choices you have for operating switches

   in a tense situation, the less likely that you'll make the

   optimum/right choice. Further, the more switches you have, the

   more likely it is that you'll suffer a switch failure thus

   creating a situation that causes you to take some action.



   Can you share the rationale that prompted your departure

   from Z19 suggestions? What value is perceived for splitting

   the ECU controls into two separate switches as opposed to

   single, double pole switches? Have you thought through the

   process(es) you'll exercise when the engine is not running

   quite right? The best Plan-B involves a minimum of activity,

   ideally free of possibilities for doing the wrong thing.



   Bob . . .

Sam

Joined: 18 May 2008
Posts: 135

Posted: Mon Nov 24, 2008 8:54 am Post subject: 2-10 SWITCH - Can this be done?

Bob,



Here are my basic thoughts and rational on the design.



The RWS EFI controller (ECU) has two separate Ignition/fuel injection controllers mounted on a single board. These are labeled as A & B.  They are almost identical and separate.

 

They allow separate +12V supply inputs, as well as separate ignition and fuel injector output triggers.  The two battery busses, main and engine, can each supply the A or B sides of the ECU. 	  Quote: 	
		   	
I am able to select a feed from either the main or the engine battery bus and supply it to either the A input of the B input.  On my drawing, the engine bus is sometimes reffered to as "backup".

 

Adding to that, are two Walbro fuel pumps, and here I continued a similar thought pattern.  That is, either the main battery bus or the engine battery bus would feed either the main EFI pump, or it's backup.  The two Facet pumps transfer fuel from the main and aux tanks to the header supply tank.

 

All of this adds up to a boatload of switches.  I invite ideas for a better way.



Sam

www.samhoskins.blogspot.com

On Mon, Nov 24, 2008 at 10:23 AM, Robert L. Nuckolls, III <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

 [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>

  



 At 08:52 AM 11/24/2008, you wrote:

 

 	  Quote: 	
		   Thanks, Bob, et al.

 

 This project could be held up as a textbook example of the laws of unintended consequences.

 

 The initial project Goal:  Make an already flying plane go faster and more efficient.

 The method:  Aerodynamic clean up and addition of Electronic Fuel Injection.

 The consequence:  The project stretching out over a year, with many items not on the original list, and worst, a not insignificant gain in weight - in direct opposition to The Goal.

 

 I have a wire count well over one hundred, 16 switches to control power and fuel, and require in the neighborhood of 20 amps to feed endurance loads!  I am using a version of Z19/RB.  I have pretty much run out of real estate for the switch grouping.

  

 That is why I am trying to include the A power source and B power source with one switch.

 

 There are lots of asides to this story, but the project really has been fun.  I'll mull all this over and see if I can find room for another #(at)$*% switch.

 

 FWIW, here is my current power distribution:



 <http://www.mistakeproofing.net/transfer/N202SH_POWER_DISTRIBUTION_07.pdf>http://www.mistakeproofing.net/transfer/N202SH_POWER_DISTRIBUTION_07.pdf 

 

 And the wire page for the coils and injectors:



 <http://www.mistakeproofing.net/transfer/injectors_and_coils.pdf>http://www.mistakeproofing.net/transfer/injectors_and_coils.pdf

  

 And the load analysis:

 <http://www.mistakeproofing.net/transfer/Load_analysis.pdf>http://www.mistakeproofing.net/transfer/Load_analysis.pdf

  	
 

   It's not clear how you ended up with so many switches. It's

   axiomatic that the more choices you have for operating switches

   in a tense situation, the less likely that you'll make the

   optimum/right choice. Further, the more switches you have, the

   more likely it is that you'll suffer a switch failure thus

   creating a situation that causes you to take some action.

 

   Can you share the rationale that prompted your departure

   from Z19 suggestions? What value is perceived for splitting

   the ECU controls into two separate switches as opposed to

   single, double pole switches? Have you thought through the

   process(es) you'll exercise when the engine is not running

   quite right? The best Plan-B involves a minimum of activity,

   ideally free of possibilities for doing the wrong thing.

 

   Bob . . .



 

 

 

 

 

 



[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

nuckolls.bob(at)cox.net
Guest

Posted: Mon Nov 24, 2008 11:07 am Post subject: 2-10 SWITCH - Can this be done?

At 10:53 AM 11/24/2008, you wrote:

 	  Quote: 	
		  Bob,



Here are my basic thoughts and rational on the design.



The <http://www.rotaryaviation.com/eficont.html>RWS EFI controller 

(ECU) has two separate Ignition/fuel injection controllers mounted 

on a single board. These are labeled as A & B.  They are almost 

identical and separate.



They allow separate +12V supply inputs, as well as separate ignition 

and fuel injector output triggers.  The two battery busses, main and 

engine, can each supply the A or B sides of the ECU.


	


 	  Quote: 	
		  I am able to select a feed from either the main or the engine 

battery bus and supply it to either the A input of the B input.  On 

my drawing, the engine bus is sometimes reffered to as "backup".


	




  Okay, why not a double-pole switch that controls each ECU

  from it's own battery bus as depicted in Z-19. This eliminates

  two switches. In other words, what do you perceive a need to

  "back up"?  It is exceedingly remote that you will experience

  two failures on any one tank full of fuel. I presume you're going

  to carry well maintained batteries (known capacity) and that your

  alternator-out endurance numbers for loss of an alternator are

  know.



 	  Quote: 	
		  Adding to that, are two Walbro fuel pumps, and here I continued a 

similar thought pattern.  That is, either the main battery bus or 

the engine battery bus would feed either the main EFI pump, or it's 

backup.  The two Facet pumps transfer fuel from the main and aux 

tanks to the header supply tank.


	


  Why not one switch per pump fed from different batteries?



  You have dual ignition already. Why not one switch to control

  magneto. One to control electronic ignition from a battery bus.

  Do the fuel injectors draw current if their associated ECU is

  powered down? If not, hook main injectors to engine battery,

  TB injector to main battery. No switches.



 	  Quote: 	
		  All of this adds up to a boatload of switches.  I invite ideas for a 

better way.


	


   I think this reduces your switch count by 3.



   Bob . . .



        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

peter(at)sportingaero.com
Guest

Posted: Mon Nov 24, 2008 11:45 am Post subject: 2-10 SWITCH - Can this be done?

Sam,  

   

I think you are over complicating the matter – I am assuming that the engine will run on either the A or the B system. Why not wire the whole of the A system from the main bus and the whole of the B system from the engine bus? Both systems become completely independent and you have 2 completely redundant systems. There is no confusion as to which side of the ECU/pump/etc is running on what.   

   

If you suspect any kind of failure switch off the system currently in use and switch on the other one. Fly to the nearest airport and investigate the failure on the ground. Use both systems regularly so you trust them both. Any further redundancy perhaps is overkill and may just introduce further (unintended?) failure modes.  

   

Regards, Peter  

   

--

Sam

Joined: 18 May 2008
Posts: 135

Posted: Tue Nov 25, 2008 4:57 am Post subject: 2-10 SWITCH - Can this be done?

Yes, I probably am over complicating the matter.  In fact, I'm sure of it.

Armed with a wide set of possibilities and a good CAD program, I can merrily

spend hours and hours woring on all sorts of permutations.



Now I'll spend a little time trying to simplicate the thing.  I appreciate

the reality check.



Thanks.



Sam

www.samhoskins.blogspot.com



On Mon, Nov 24, 2008 at 1:38 PM, Peter Pengilly <peter(at)sportingaero.com>wrote:



[quote]  Sam,



 I think you are over complicating the matter – I am assuming that the

 engine will run on either the A or the B system. Why not wire the whole of

 the A system from the main bus and the whole of the B system from the engine

 bus? Both systems become completely independent and you have 2 completely

 redundant systems. There is no confusion as to which side of the

 ECU/pump/etc is running on what.



 If you suspect any kind of failure switch off the system currently in use

 and switch on the other one. Fly to the nearest airport and investigate the

 failure on the ground. Use both systems regularly so you trust them both.

 Any further redundancy perhaps is overkill and may just introduce further

 (unintended?) failure modes.



 Regards, Peter



 --

_________________
Sam Hoskins
www.samhoskins.blogspot.com

nuckolls.bob(at)cox.net
Guest

Posted: Tue Nov 25, 2008 7:05 am Post subject: 2-10 SWITCH - Can this be done?

At 01:23 PM 11/24/2008, you wrote:

 	  Quote: 	
		  Thanks Bob.  Let me cogitate over that a few hours.

Sam



On Mon, Nov 24, 2008 at 1:02 PM, Robert L. Nuckolls, III 

<<mailto:nuckolls.bob(at)cox.net>nuckolls.bob(at)cox.net> wrote:


<<mailto:nuckolls.bob(at)cox.net>nuckolls.bob(at)cox.net>



At 10:53 AM 11/24/2008, you wrote:

Bob,



Here are my basic thoughts and rational on the design.



The 

<<http://www.rotaryaviation.com/eficont.html>http://www.rotaryaviation.com/eficont.html>RWS 

EFI controller (ECU) has two separate Ignition/fuel injection 

controllers mounted on a single board. These are labeled as A & 

B.  They are almost identical and separate.

They allow separate +12V supply inputs, as well as separate ignition 

and fuel injector output triggers.  The two battery busses, main and 

engine, can each supply the A or B sides of the ECU.

I am able to select a feed from either the main or the engine 

battery bus and supply it to either the A input of the B input.  On 

my drawing, the engine bus is sometimes reffered to as "backup".


	


    Yes, there are MANY combinations of things you can do that

    function as advertised. I've seen airplanes at fly-ins that

    have LOTS of switches.



    Your task as system designer and integrator of components is

    to 'optimize' the design. I.e., what components can be eliminated

    to reduce complexity from the (1) perspective of reliability and

    space savings and (2) reduce pilot workload for having to make

    the right decisions for continued flight when some part of the

    system decides to throw a temper tantrum.



    I'll suggest you reconsider your design with the notion that

    (1) the hardware SHARED by plan-a and plan-b systems needs to

    be an absolute minimum. (2) Likelihood of having two failures

    in the airplane on any single tank full of fuel is exceedingly

    rare (read insignificant). (3) Manage energy sources and loads

    to meet design goals for endurance when a failure does occur.



    I'm certain that you'll discover a way to reduce numbers of

    switches down to independent control of system-A and system-B

    probably as simple as one switch per system. Does each ECU

    have its own dedicated fuel pump or can either pump supply

    either system? If the former, combine the pumps on the

    ECU controls. If the later, one switch per pump is called for.



    Bob . . .

Sam

Joined: 18 May 2008
Posts: 135

Posted: Tue Nov 25, 2008 8:03 am Post subject: 2-10 SWITCH - Can this be done?

Either pump can supply either system.  The second EFI pump is just a back-up

 to the first.

 

 I think these automotive pumps are very reliable and I won't ever need the

 backup unit, but since it keeps the fan turning, it's pretty important to

 have the backup.

 

 The fuel system has a bypass-type pressure regulator.  When I originally set

 this up, I wanted to design it so either pump could be on-line, but not

 both, so as not to overload the regulator.  That lead to the set-up that

 required two switches and an either/or condition. I don't really know the

 capacity of the regulator, it just seemed like a good idea.

 

 Instead, I think I will go back to one switch per pump, dedicate them to

 main/engine, and arrange the switch bank to better group things together -

 make the error proofing visual rather than mechanical.

 

 As you suggested, I am looking into the characteristics of the internally

 excited coils and the fuel injectors to see if there is any current draw

 when there is no ECU input.  My first reaction was to insist that they be

 switched, mostly for maintenance purposes. But on second, thought maybe a

 panel breaker would do the trick - provided there is no current draw.

 

 Yes, the switch count is coming down.

 

 Sam

www.samhoskins.blogspot.com

 	  Quote: 	
		  	




On Tue, Nov 25, 2008 at 9:04 AM, Robert L. Nuckolls, III <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

 [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>

  



 At 01:23 PM 11/24/2008, you wrote:

 

 	  Quote: 	
		   Thanks Bob.  Let me cogitate over that a few hours.

 Sam

 

 

 



 On Mon, Nov 24, 2008 at 1:02 PM, Robert L. Nuckolls, III <<mailto:nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

  --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <<mailto:nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> 

 

 At 10:53 AM 11/24/2008, you wrote:

 Bob,

 

 Here are my basic thoughts and rational on the design.

 



 The <<http://www.rotaryaviation.com/eficont.html>http://www.rotaryaviation.com/eficont.html>RWS EFI controller (ECU) has two separate Ignition/fuel injection controllers mounted on a single board. These are labeled as A & B.  They are almost identical and separate. 

 

 

 They allow separate +12V supply inputs, as well as separate ignition and fuel injector output triggers.  The two battery busses, main and engine, can each supply the A or B sides of the ECU.

 

 

 I am able to select a feed from either the main or the engine battery bus and supply it to either the A input of the B input.  On my drawing, the engine bus is sometimes reffered to as "backup".

 

	
 

    Yes, there are MANY combinations of things you can do that

    function as advertised. I've seen airplanes at fly-ins that

    have LOTS of switches.

 

    Your task as system designer and integrator of components is

    to 'optimize' the design. I.e., what components can be eliminated

    to reduce complexity from the (1) perspective of reliability and

    space savings and (2) reduce pilot workload for having to make

    the right decisions for continued flight when some part of the

    system decides to throw a temper tantrum.

 

    I'll suggest you reconsider your design with the notion that

    (1) the hardware SHARED by plan-a and plan-b systems needs to

    be an absolute minimum. (2) Likelihood of having two failures

    in the airplane on any single tank full of fuel is exceedingly

    rare (read insignificant). (3) Manage energy sources and loads

    to meet design goals for endurance when a failure does occur.

 

    I'm certain that you'll discover a way to reduce numbers of

    switches down to independent control of system-A and system-B

    probably as simple as one switch per system. Does each ECU

    have its own dedicated fuel pump or can either pump supply

    either system? If the former, combine the pumps on the

    ECU controls. If the later, one switch per pump is called for.

 

    Bob . . .

 

 

 

 

 

 



[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

klehman(at)albedo.net
Guest

Posted: Tue Nov 25, 2008 8:04 pm Post subject: 2-10 SWITCH - Can this be done?

Sam

FWIW there have been several cases of EFI pump failure over the years so 

I agree that a backup is a very good idea. On my subaru the fuel 

pressure goes up 2 or 3 psi if I run two paralleled pumps 

simultaneously. I'm aware of similar reports with other regulators. That 

pressure increase is pretty insignificant as far as the engine is 

concerned as injector flow varies with the square root of the pressure. 

I no longer bother to run two pumps for takeoff and landing but my 

switches are laid out such that all engine problems are dealt with by 

positioning all switches up with one hand without having to look at 

them. A simple emergency procedure like that is well worth some effort 

to implement if you can.



The injectors that I'm aware of operate by grounding one side of the 

coil through a solid state "transistor". There have been a few cases of 

injectors locking on from a shorted "transistor" or wiring. I don't know 

if there have been any from the coil shorting internally to ground. 

However a locked on injector will not likely be noticed at full power 

and maybe not even at cruise power. Definitely noticeable upon power 

reduction.



Ken



Sam Hoskins wrote:

 	  Quote: 	
		   Either pump can supply either system.  The second EFI pump is just a back-up

 to the first.

 

 I think these automotive pumps are very reliable and I won't ever need the

 backup unit, but since it keeps the fan turning, it's pretty important to

 have the backup.

 

 The fuel system has a bypass-type pressure regulator.  When I originally set

 this up, I wanted to design it so either pump could be on-line, but not

 both, so as not to overload the regulator.  That lead to the set-up that

 required two switches and an either/or condition. I don't really know the

 capacity of the regulator, it just seemed like a good idea.

 

 Instead, I think I will go back to one switch per pump, dedicate them to

 main/engine, and arrange the switch bank to better group things together -

 make the error proofing visual rather than mechanical.

 

 As you suggested, I am looking into the characteristics of the internally

 excited coils and the fuel injectors to see if there is any current draw

 when there is no ECU input.  My first reaction was to insist that they be

 switched, mostly for maintenance purposes. But on second, thought maybe a

 panel breaker would do the trick - provided there is no current draw.

 

 Yes, the switch count is coming down.

 

 Sam

 www.samhoskins.blogspot.com <http://www.samhoskins.blogspot.com>

Sam

Joined: 18 May 2008
Posts: 135

Posted: Wed Nov 26, 2008 5:37 am Post subject: 2-10 SWITCH - Can this be done?

Okay.



I have completely split the two EFI fuel pumps - one from the engine bat bus and one from the main bat bus.



The four primary injectors are now fed solely by the main bat bus and the backup throttle body (TB) injector is fed solely by the engine bat bus.

 

A single double-pole switch turns on both A & B sides of the ECU - OFF/BOTH.  The ECU has it's own dedicated panel with it's own A/B switch, not shown here.



I have not figured another, more independent way to feed the four ignition coils from either the main or bat bus, so I guess I'll leave that switch arrangement alone.  I  think it's important to be able to feed from either bus.

 

I have also rearranged the remaining switches a little better.



Here are the modified arrangements:



http://www.mistakeproofing.net/transfer/Isolated_POWER_DISTRIBUTION.pdf

 

http://www.mistakeproofing.net/transfer/Switches_POWER_DISTRIBUTION.pdf



Thanks for everyone's input.  A team always has a better result than just individuals slugging away.

  	  Quote: 	
		  Sam 	




On Tue, Nov 25, 2008 at 9:04 AM, Robert L. Nuckolls, III <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

 [quote]--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>

  



 At 01:23 PM 11/24/2008, you wrote:

 

 	  Quote: 	
		   Thanks Bob.  Let me cogitate over that a few hours.

 Sam

 

 

 



 On Mon, Nov 24, 2008 at 1:02 PM, Robert L. Nuckolls, III <<mailto:nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> wrote:

  --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <<mailto:nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)>nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> 

 

 At 10:53 AM 11/24/2008, you wrote:

 Bob,

 

 Here are my basic thoughts and rational on the design.

 



 The <<http://www.rotaryaviation.com/eficont.html>http://www.rotaryaviation.com/eficont.html>RWS EFI controller (ECU) has two separate Ignition/fuel injection controllers mounted on a single board. These are labeled as A & B.  They are almost identical and separate. 

 

 

 They allow separate +12V supply inputs, as well as separate ignition and fuel injector output triggers.  The two battery busses, main and engine, can each supply the A or B sides of the ECU.

 

 

 I am able to select a feed from either the main or the engine battery bus and supply it to either the A input of the B input.  On my drawing, the engine bus is sometimes reffered to as "backup".

 

	
 

    Yes, there are MANY combinations of things you can do that

    function as advertised. I've seen airplanes at fly-ins that

    have LOTS of switches.

 

    Your task as system designer and integrator of components is

    to 'optimize' the design. I.e., what components can be eliminated

    to reduce complexity from the (1) perspective of reliability and

    space savings and (2) reduce pilot workload for having to make

    the right decisions for continued flight when some part of the

    system decides to throw a temper tantrum.

 

    I'll suggest you reconsider your design with the notion that

    (1) the hardware SHARED by plan-a and plan-b systems needs to

    be an absolute minimum. (2) Likelihood of having two failures

    in the airplane on any single tank full of fuel is exceedingly

    rare (read insignificant). (3) Manage energy sources and loads

    to meet design goals for endurance when a failure does occur.

 

    I'm certain that you'll discover a way to reduce numbers of

    switches down to independent control of system-A and system-B

    probably as simple as one switch per system. Does each ECU

    have its own dedicated fuel pump or can either pump supply

    either system? If the former, combine the pumps on the

    ECU controls. If the later, one switch per pump is called for.

 

    Bob . . .

 

 

 

 

 

 



[b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

mrspudandcompany(at)veriz
Guest

Posted: Wed Nov 26, 2008 7:16 am Post subject: 2-10 SWITCH - Can this be done?

Okay.

		

		I have completely split the two EFI fuel pumps - one from

the engine bat bus and one from the main bat bus.

		

		The four primary injectors are now fed solely by the main

bat bus and the backup throttle body (TB) injector is fed solely by the

engine bat bus.

		

		A single double-pole switch turns on both A & B sides of the

ECU - OFF/BOTH.  The ECU has it's own dedicated panel with it's own A/B

switch, not shown here.

		

		I have not figured another, more independent way to feed the

four ignition coils from either the main or bat bus, so I guess I'll leave

that switch arrangement alone.  I  think it's important to be able to feed

from either bus.

		

		I have also rearranged the remaining switches a little

better.

		

		Here are the modified arrangements:

		

	

http://www.mistakeproofing.net/transfer/Isolated_POWER_DISTRIBUTION.pdf

		

	

http://www.mistakeproofing.net/transfer/Switches_POWER_DISTRIBUTION.pdf

		

		



Sam,



Going back to your first request for info on this thread, you asked how to

operate either of 2 ECU's from 2 separate power sources through 1 switch.

Several individuals indicated that it is not a good thing to go through 1

switch and thus create a "single point of failure" for both systems.  You

now have a single point of failure in your ECU ON / Off switch. 

Assuming that you will need to have 1 ECU and 1 EFI pump operating

continuously, wire ECU A and EFI# 1 through a DPDT  switch, the one you

presently have for your ECU ON / OFF, connected as follows:



Engine Battery Bus to pin 2; Engine Battery Bus to pin 3 (fused separately);

ECU A to pin 1; EFI Pump 1 to pin 4.  Repeat similar wiring from Main

battery Bus to ECU B and EFI pump 2.  This will give you a totally separate,

redundant system and will also eliminate 1 switch.



Now when you turn on switch #1, ECU A and EFI fuel pump# 1 will be on,

supplied with power from the Engine Battery Bus.  If you turn on Switch# 2,

ECU B and EFI fuel pump# 2 will be on, powered from Main Battery Bus.



This is only one of many ways to wire a fault tolerant redundant system.  I

am sure others will have different ideas for wiring schemes.

winmail.dat

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Sam

Joined: 18 May 2008
Posts: 135

Posted: Wed Nov 26, 2008 7:45 am Post subject: 2-10 SWITCH - Can this be done?

Roger, you are correct.  My oops.



Right after I hit the send button I realized my error.  I changed it so the ECU is controlled by two independent switches.  I had to add in another switch, but I laid out the panel to be more logical.  The second row is all the backup stuff.  You can see that if you click on the links below.

 

This is what I came up with before your e-mail.  I'll spend a few minutes and look over your suggestions.



Thanks.



My bad.



Sam

"I'm not a real airplane builder.  I just play one at home".

 

On Wed, Nov 26, 2008 at 9:12 AM, ROGER &  JEAN CURTIS <mrspudandcompany(at)verizon.net (mrspudandcompany(at)verizon.net)> wrote:

[quote]                 Okay.

 

                 I have completely split the two EFI fuel pumps - one from

 the engine bat bus and one from the main bat bus.

 

                 The four primary injectors are now fed solely by the main

 bat bus and the backup throttle body (TB) injector is fed solely by the

 engine bat bus.

 

                 A single double-pole switch turns on both A & B sides of the

 ECU - OFF/BOTH.  The ECU has it's own dedicated panel with it's own A/B

 switch, not shown here.

 

                 I have not figured another, more independent way to feed the

 four ignition coils from either the main or bat bus, so I guess I'll leave

 that switch arrangement alone.  I  think it's important to be able to feed

 from either bus.

 

                 I have also rearranged the remaining switches a little

 better.

 

                 Here are the modified arrangements:

 

 

 http://www.mistakeproofing.net/transfer/Isolated_POWER_DISTRIBUTION.pdf

 

 

 http://www.mistakeproofing.net/transfer/Switches_POWER_DISTRIBUTION.pdf

 

 

 

 

Sam,

 

 Going back to your first request for info on this thread, you asked how to

 operate either of 2 ECU's from 2 separate power sources through 1 switch.

 Several individuals indicated that it is not a good thing to go through 1

 switch and thus create a "single point of failure" for both systems.  You

 now have a single point of failure in your ECU ON / Off switch.

 Assuming that you will need to have 1 ECU and 1 EFI pump operating

 continuously, wire ECU A and EFI# 1 through a DPDT  switch, the one you

 presently have for your ECU ON / OFF, connected as follows:

 

 Engine Battery Bus to pin 2; Engine Battery Bus to pin 3 (fused separately);

 ECU A to pin 1; EFI Pump 1 to pin 4.  Repeat similar wiring from Main

 battery Bus to ECU B and EFI pump 2.  This will give you a totally separate,

 redundant system and will also eliminate 1 switch.

 

 Now when you turn on switch #1, ECU A and EFI fuel pump# 1 will be on,

 supplied with power from the Engine Battery Bus.  If you turn on Switch# 2,

 ECU B and EFI fuel pump# 2 will be on, powered from Main Battery Bus.

 

 This is only one of many ways to wire a fault tolerant redundant system.  I

 am sure others will have different ideas for wiring schemes.

 

 [b]

_________________
Sam Hoskins
www.samhoskins.blogspot.com

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