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EXP 2 Bus workaround
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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Oct 25, 2013 6:43 pm Post subject: EXP 2 Bus workaround

At 07:35 PM 10/25/2013, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Fred Klein <fklein(at)orcasonline.com>



 Bob, thank you for your analysis and recommendations...they greatly enhance my learning experience here...please see my indents below...I have additional comments (later) on your posted circuit diagram of this morning...Fred 	


    We're getting the cart out in front. Let's get a 98%

    golden list of electro-whizzies and where they'll

    get powered.



    The Z-08 drawing is just architecture for now, the mechanism

    by which an EXP-Bus duplicates or emulates the philosophy

    is a separate task.



  	  Quote: 	
		  > 

 >  (3) Take E-Bus alternate feed directly from the battery on

 >  it's own 7A fuse and 14AWG wire . . . 10A fuse if determined

 >  necessary later.



                  I can do that; this adds another wire forward from rear battery to bus...What's the advantage of doing this rather than using a short wire to the Engine (MP) bus, as long as the total E-bus + MP bus loads can be handled by the EXP Bus circuit from which power is being drawn? Normally (I believe the) E-bus alternate feed will ONLY be activated in conjunction w/ the Engine (MP) bus alternate feed (sized accordingly) is activated. 	


     We can thrash this detail later . . .



 



 

  	  Quote: 	
		                    Let's talk about the 2 fuel pumps for a MPEFI engine. Unlike w/ carb engines, the 2nd pump is not used as a boost pump. I'm advised that w/ a MPEFI engine, one never wants to run more than ONE pump at a time due to excessive pressure in the system. 	


    How does this happen? I understand that there's a pressure

    regulator downstream of the pump outputs. Paralleling two

    active pumps only increases potential for flow . . . like

    hooking two batteries in parallel.



  	  Quote: 	
		  >  (7) Suggest separate fuses for each injector and coil

 >  assuming engine produces some useable power with any

 >  one fuse open.



                  This sounds like a novel idea...I'm wondering if  anyone's ever done this before?.. how much increased complexity is entailed?...and whether or not historical rates of injector and coil failures suggest that this would be prudent? 	


   I've seen this before. The idea is that no single failure

   takes out all injectors and an engine will produce useful

   power with one injector down.



 

  	  Quote: 	
		  >  ( Starter can control from main bus.



                  True...and...w/ my particular combination of engine, reduction ratio, propeller, and aircraft performance envelope, although I THINK that with engine out, prop would windmill sufficient to restart engine, if Master switch was OFF, I'd like to be able to spin the starter...that was the INTENT of what the diagram shows...What do you think?...I'm unsure as to whether or not the wiring diagram allows for that to happen. 	


   Is anyone flying this combination of hardware? How much does

   IAS need to be reduced to stop a windmilling prop? The few

   times I stopped the prop on a TC airplane I had to really

   work at it. The idea that one needs access to a starter

   motor in flight is mostly without foundation. This is a

   fact you need to resolve for your harware combination. 



 

  	  Quote: 	
		  > (9) Turn existing avionics bus into e-bus, convert

 >  old avionics master into alternate feed path control

 >  switch. Normal feed path comes from main bus through

 >  diode.



                  I'm completely in the dark as to my understanding of what physical changes must be made to the EXP Bus to accomplish this.

 	


     Later . . . I don't think it's going to be difficult.



  	  Quote: 	
		  > 

 >  (10) You speak to "room for breakers/fuses on panel"

 >  suggest these be out of sight, of reach.



                  That would be possible of course, though if CBs are used, questionable. I'm presuming that you want them out of sight to reduce workload in an emergency, and to avoid possibly exacerbating conditions by resetting popped CBs...is that so? 	


     The only time a fuse or breaker opens is because something

     is broke (which means new fuse doesn't help) or the circuit

     protection is undersized (nuisance trip - which on an OBAM

     aircraft gets fixed). Hence, no value for being able to see/reach

     breakers and fuses.



 

 

   Bob . . .    [quote][b]

livingjw(at)earthlink.net
Guest

Posted: Fri Oct 25, 2013 8:47 pm Post subject: EXP 2 Bus workaround

I am still stumped as to why you would       recommend one battery. I could agree if the one alternator is       guaranteed to work without the battery in the circuit, but not       without that backup. You must think batteries are much more       reliable than I do. 

       

       John

       

       

       

       On 10/25/2013 10:42 PM, Robert L. Nuckolls, III wrote:

     

     [quote]       At 07:35 PM 10/25/2013, you wrote:

        	  Quote: 	
		  -->         AeroElectric-List message         posted by: Fred Klein <fklein(at)orcasonline.com> (fklein(at)orcasonline.com)

         

         Bob, thank you for your analysis and recommendations...they         greatly         enhance my learning experience here...please see my indents         below...I         have additional comments (later) on your posted circuit diagram         of this         morning...Fred 	
       

          We're getting the cart out in front. Let's get a 98%

            golden list of electro-whizzies and where they'll

            get powered.

         

            The Z-08 drawing is just architecture for now, the         mechanism

            by which an EXP-Bus duplicates or emulates the         philosophy

            is a separate task.

         

               	  Quote: 	
		  > 

         >  (3) Take E-Bus alternate feed directly from the battery         on

         >  it's own 7A fuse and 14AWG wire . . . 10A fuse if         determined

         >  necessary later.

         

                                    I can do that;         this adds another wire forward from rear battery to bus...What's         the         advantage of doing this rather than using a short wire to the         Engine (MP)         bus, as long as the total E-bus + MP bus loads can be handled by         the EXP         Bus circuit from which power is being drawn? Normally (I believe         the)         E-bus alternate feed will ONLY be activated in conjunction w/         the Engine         (MP) bus alternate feed (sized accordingly) is         activated. 	
       

           We can thrash this detail later . . .

         

         

         

         

               	  Quote: 	
		                                        Let's talk about         the 2 fuel pumps for a MPEFI engine. Unlike w/ carb engines, the         2nd pump         is not used as a boost pump. I'm advised that w/ a MPEFI engine,         one         never wants to run more than ONE pump at a time due to excessive         pressure         in the system. 	
       

          How does this happen? I understand that there's a         pressure

            regulator downstream of the pump outputs. Paralleling         two

            active pumps only increases potential for flow . . .         like

            hooking two batteries in parallel.

         

               	  Quote: 	
		  >  (7) Suggest         separate fuses for each injector and coil

         >  assuming engine produces some useable power with any

         >  one fuse open.

         

                                    This sounds like         a novel idea...I'm wondering if  anyone's ever done this         before?..         how much increased complexity is entailed?...and whether or not         historical rates of injector and coil failures suggest that this         would be         prudent? 	
       

         I've seen this before. The idea is that no single failure

           takes out all injectors and an engine will produce useful

           power with one injector down.

         

         

               	  Quote: 	
		  >  ( Starter can         control from main bus.

         

                                    True...and...w/         my particular combination of engine, reduction ratio, propeller,         and         aircraft performance envelope, although I THINK that with engine         out,         prop would windmill sufficient to restart engine, if Master         switch was         OFF, I'd like to be able to spin the starter...that was the         INTENT of         what the diagram shows...What do you think?...I'm unsure as to         whether or         not the wiring diagram allows for that to happen. 	
       

         Is anyone flying this combination of hardware? How much         does

           IAS need to be reduced to stop a windmilling prop? The few

           times I stopped the prop on a TC airplane I had to really

           work at it. The idea that one needs access to a starter

           motor in flight is mostly without foundation. This is a

           fact you need to resolve for your harware combination. 

         

         

               	  Quote: 	
		  > (9) Turn         existing         avionics bus into e-bus, convert

         >  old avionics master into alternate feed path control

         >  switch. Normal feed path comes from main bus through

         >  diode.

         

                                    I'm completely in         the dark as to my understanding of what physical changes must be         made to         the EXP Bus to accomplish this.

       	
       

           Later . . . I don't think it's going to be         difficult.

         

               	  Quote: 	
		  > 

         >  (10) You speak to "room for breakers/fuses on         panel"

         >  suggest these be out of sight, of reach.

         

                                    That would be         possible of course, though if CBs are used, questionable. I'm         presuming         that you want them out of sight to reduce workload in an         emergency, and         to avoid possibly exacerbating conditions by resetting popped         CBs...is         that so? 	
       

           The only time a fuse or breaker opens is because         something

             is broke (which means new fuse doesn't help) or the         circuit

             protection is undersized (nuisance trip - which on an         OBAM

             aircraft gets fixed). Hence, no value for being able         to see/reach

             breakers and fuses.

         

         

                

             Bob . . .                   	  Quote: 	
		  

	
       [b]

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Fri Oct 25, 2013 10:41 pm Post subject: EXP 2 Bus workaround

On Oct 25, 2013, at 7:42 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   	  Quote: 	
		                   Let's talk about the 2 fuel pumps for a MPEFI engine. Unlike w/ carb engines, the 2nd pump is not used as a boost pump. I'm advised that w/ a MPEFI engine, one never wants to run more than ONE pump at a time due to excessive pressure in the system. 	


   How does this happen? I understand that there's a pressure

   regulator downstream of the pump outputs. Paralleling two

   active pumps only increases potential for flow . . . like

   hooking two batteries in parallel.

	




		Bob...I get your point about pressure...let me try to get better info...it may be that restriction due to size of return fuel line can't accept the increased flow...I'll check back about this.





 	  Quote: 	
		   	  Quote: 	
		  >  ( Starter can control from main bus.



                 True...and...w/ my particular combination of engine, reduction ratio, propeller, and aircraft performance envelope, although I THINK that with engine out, prop would windmill sufficient to restart engine, if Master switch was OFF, I'd like to be able to spin the starter...that was the INTENT of what the diagram shows...What do you think?...I'm unsure as to whether or not the wiring diagram allows for that to happen. 	


  Is anyone flying this combination of hardware? How much does

  IAS need to be reduced to stop a windmilling prop? The few

  times I stopped the prop on a TC airplane I had to really

  work at it. The idea that one needs access to a starter

  motor in flight is mostly without foundation. This is a

  fact you need to resolve for your harware combination. 

	




		Bob...I'm getting some data on this.





		Fred



 [quote][b]

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Fri Oct 25, 2013 10:52 pm Post subject: EXP 2 Bus workaround

On Oct 25, 2013, at 6:32 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  Attached are the preliminary sketches for my current

thoughts on an architecture for single battery, single

alternator, electrically dependent engine. This line of

thinking is being developed as an preferred alternative

to Z-19.

	




		Bob...I'm delighted that my queries have triggered your taking a fresh look at Z-19...and presumably, Z-19RB.

 	  Quote: 	
		  

This architecture has roots in Z-11 Three-Bus structure

with the addition of a Motive Power Bus (engine). With

the term E-bus already in legacy use, the MP-Bus terminology

offers a stand-out label that avoids confusion.

	




		...perhaps it won't be too long before MP busses will morph into ones intended for truly all electric power trains...

 	  Quote: 	
		  

The major difference is the addition of the MP-bus having

normal feedpath from the main bus, alternate feedpath from

the battery . . . same as the E-Bus except BOTH pathways

have panel mounted switches. The e-bus is always hot any

time the main bus is hot, but the MP-Bus as power to the

engine needs to be controlled through both pathways.



I'm thinking that the EXP-bus can be folded into this

architecture by conversion of battery switch to DC master

and take alternator field through second pole. Convert

the 'avionice master' Engine A. Use switch between the

big red rockers as e-bus alternate feed. Switch to right

of Engine A is Engine B.

	




		From the get-go, my intent has been to supplement the capabilities of the EXP Bus to provide for the special requirements for a MPEFI engine AND to provide the alternate feeds featured in AeroElectric's Z-xx diagrams in case something goes amiss.

		I question your suggestion to:

 	  Quote: 	
		  Use switch between the big red rockers as e-bus alternate feed. Switch to right of Engine A is Engine B. 	


 		I'm reluctant to interpose within the row of EXP Bus rockers, switches which would only be used during an emergency. 

		Conceptually, I much prefer the notion of having a row of rockers, all of which are used in the course of normal operations...and a second, distinctly different row of rockers which will only be used during emergencies.

		(The wide, red, Master switch at the left end...distinctive in both width and color...is of course used both in normal and emergency ops.)

		Organizing the panel in this manner...at least to me...sets the stage for calm and cool actions when under stress.

		I understand your desire for me to proceed w/ listing of elec loads for all components...a task I recognise as essential...but first I want to be confident that I understand the big picture. And the big picture for me is how we supplement the capabilities of the EXP Bus in order to have the benefits of engine and endurance busses with alternate feeds from the battery.

		Notwithstanding the shortcomings, some poor choices, and undoubtedly some serious errors, the last diagram I posted (Revision #XX) did two things of note: 

		First, it pulls power from the EXP Master Bus for the MP (engine) bus from 2 - 11 amp circuits, AUX1 and AUX2. (...now I don't know exactly how those 2 circuits can be combined, but something tells me there's a way which is simple and direct...)

		Second, the Revision XX diagram shows the EXP Avionics Bus powering the E-bus (endurance) from a 7 amp circuit. (...btw, I don't understand the notion that we should be rid of the avionics master switch...). Also...note that w/ Skyview and the back up GPS both having their own back up batteries, if either the Master switch or the Avionics Master is turned off and the E-bus Alternate Feed is energized, we'll be back in business w/ a full suite of avionics.

		It strikes me that this approach is elegant, simple, and direct; I shudder at the thought of altering any part of the circuitry within the EXP Bus other than changing some Fast-on spades of a couple of switches and relabeling them. 

		I'm baffled when you write,

		

 	  Quote: 	
		  Old avionics bus becomes e-bus. 	




		...as I look at the circuit board of the EXP Bus, I haven't a clue how this can happen and create the alternate feed intrinsic w/ the e-bus concept...way outside my comfort zone to poke around in that circuit board.

		Fred



 [quote][b]

klehman(at)albedo.net
Guest

Posted: Sat Oct 26, 2013 2:52 am Post subject: EXP 2 Bus workaround

FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work 

fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes up 

no more than 2 psi. even with my somewhat restrictive 5/16" return 

plumbing. Some fellows run both pumps for landing and takeoff. Selecting 

both on is the first thing we do if the engine is not running properly. 

Injector flow increases with the square root of pressure so that is not 

an issue since normal EFI pressures run around 38 psi above manifold 

pressure.

Ken

On 25/10/2013 10:42 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   *

 *

> Let's talk about the 2 fuel pumps for a MPEFI engine. Unlike w/ carb

> engines, the 2nd pump is not used as a boost pump. I'm advised that w/

> a MPEFI engine, one never wants to run more than ONE pump at a time

> due to excessive pressure in the system.

 *   How does this happen? I understand that there's a pressure

     regulator downstream of the pump outputs. Paralleling two

     active pumps only increases potential for flow . . . like

     hooking two batteries in parallel.*

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 5:05 am Post subject: EXP 2 Bus workaround

At 11:44 PM 10/25/2013, you wrote:

  	  Quote: 	
		  I am still stumped as to why you would recommend one battery. I could agree if the one alternator is guaranteed to work without the battery in the circuit, but not without that backup. You must think batteries are much more reliable than I do. 

 	


   Oky, let's ex[;pre that premise. What in your

   studies and/or experience with batteries leads

   you to believe that they demonstrate a risky,

   in-service failure rate?



   Before you add a second battery, are there things

   that can be done to mitigate your concerns and

   reduce in-service failures to acceptable risk

   levels?



   Recall that the original premise for dual batteries

   had nothing to do with worries for battery failure

   and everything to do with walling off known quantities

   of energy off to do separate tasks . . . where one

   of those tasks was critical to continued flight:

   keep the engine running. The two battery concept was

   never intended to be a hedge against the failure

   of one battery.



 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 5:50 am Post subject: EXP 2 Bus workaround

At 01:51 AM 10/26/2013, you wrote:



 On Oct 25, 2013, at 6:32 AM, Robert L. Nuckolls, III wrote:



  Attached are the preliminary sketches for my current thoughts on an architecture for single battery, single alternator, electrically dependent engine. This line of thinking is being developed as an preferred alternative to Z-19.



 Bob...I'm delighted that my queries have triggered your taking a fresh look at Z-19...and presumably, Z-19RB.



  This architecture has roots in Z-11 Three-Bus structure with the addition of a Motive Power Bus (engine). With the term E-bus already in legacy use, the MP-Bus terminology offers a stand-out label that avoids confusion.



 ...perhaps it won't be too long before MP busses will morph into ones intended for truly all electric power trains...



  The major difference is the addition of the MP-bus having normal feedpath from the main bus, alternate feedpath from the battery . . . same as the E-Bus except BOTH pathways have panel mounted switches. The e-bus is always hot any time the main bus is hot, but the MP-Bus as power to the engine needs to be controlled through both pathways.

  I'm thinking that the EXP-bus can be folded into this architecture by conversion of battery switch to DC master and take alternator field through second pole. Convert the 'avionice master' Engine A. Use switch between the big red rockers as e-bus alternate feed. Switch to right of Engine A is Engine B.



 From the get-go, my intent has been to supplement the capabilities of the EXP Bus to provide for the special requirements for a MPEFI engine AND to provide the alternate feeds featured in AeroElectric's Z-xx diagrams in case something goes amiss.



 I question your suggestion to:



 Use switch between the big red rockers as e-bus alternate feed. Switch to right of Engine A is Engine B.



 I'm reluctant to interpose within the row of EXP Bus rockers, switches which would only be used during an emergency. 



 Conceptually, I much prefer the notion of having a row of rockers, all of which are used in the course of normal operations...and a second, distinctly different row of rockers which will only be used during emergencies.



    Please . . . purge the work EMERGENCY from your

    thought processes. Things on airplanes break all

    the time. If they did not, FBO maintenance shops

    would be out of business and Jiffy-Lube could move

    into the empty space while adding a wash-rack.



    You have Plan-A, everything works in accordance

    with the refined constellation of design goals.

    Then there is Plan-B, something broke . . . a

    condition that has been anticipated in our FEMA

    and we're dealing with it under a sub-set of

    the original design goals. Then there's Plan-C,

    supported by some goodies in the flight bag

    that describe yet a smaller sub-set of original

    design goals.



    An airplane configured artfully conducted FMEA

    operating by a pilot who understands the machine's

    strengths and weaknesses does not experience

    electrical emergencies . . . only events of

    in-service failure or wear-out that will need

    to be hammered on once you've arrived at your

    intended destination. 



 

 (The wide, red, Master switch at the left end...distinctive in both width and color...is of course used both in normal and emergency ops.)



 Organizing the panel in this manner...at least to me...sets the stage for calm and cool actions when under stress.



 I understand your desire for me to proceed w/ listing of elec loads for all components...a task I recognise as essential...but first I want to be confident that I understand the big picture. And the big picture for me is how we supplement the capabilities of the EXP Bus in order to have the benefits of engine and endurance busses with alternate feeds from the battery.



    The BIG picture is that drawing I published.

    You're getting distracted by the existence of

    the EXP-Bus.



 Notwithstanding the shortcomings, some poor choices, and undoubtedly some serious errors, the last diagram I posted (Revision #XX) did two things of note: 



 First, it pulls power from the EXP Master Bus for the MP (engine) bus from 2 - 11 amp circuits, AUX1 and AUX2. (...now I don't know exactly how those 2 circuits can be combined, but something tells me there's a way which is simple and direct...)



 Second, the Revision XX diagram shows the EXP Avionics Bus powering the E-bus (endurance) from a 7 amp circuit. (...btw, I don't understand the notion that we should be rid of the avionics master switch...). Also...note that w/ Skyview and the back up GPS both having their own back up batteries, if either the Master switch or the Avionics Master is turned off and the E-bus Alternate Feed is energized, we'll be back in business w/ a full suite of avionics.



   The avionics master switch was a flawed idea

   from the get-go. I was at Cessna when the thing

   was birthed and I've come to understand how

   we marched off down that no-value-added

   path. See:

   

  http://tinyurl.com/pgcgx9m



 

 It strikes me that this approach is elegant, simple, and direct; I shudder at the thought of altering any part of the circuitry within the EXP Bus other than changing some Fast-on spades of a couple of switches and relabeling them. 



   Ignore the EXP=Bus for now, we need to

   make the architecture work first.



 I'm baffled when you write,

 "Old avionics bus becomes e-bus." 



   There is presently an avionics master switch that

   controls all power to a chunk of copper glued

   to the epoxy-glas that distributes power to terminals

   on the board through an array of poly-fuses. This

   is your 'avionics' bus which I believe can become

   your new e-bus. 



 

 ...as I look at the circuit board of the EXP Bus, I haven't a clue how this can happen and create the alternate feed intrinsic w/ the e-bus concept...way outside my comfort zone to poke around in that circuit board.



   It's just "wires" glued to a piece of epoxy-glas.

   Nothing happens on that assembly that a large

   number of our contemporaries haven't done with

   fuses, wires, breakers and switches. The marketing-hook

   for an EXP-Bus is it's relative complexity for stuffing

   a lot of activity into a small volume and then offering

   it to the customer as, "Here, look at all these things

   we did FOR you so that you don't HAVE to."



   The question never asked and answered is, "Does that

   assembly DO things that people who choose not to

   use your product will wish they had included at

   some later time?"  In other words, what is the

   return on investment for you having exchanged your

   dollars for their time, talents and resources?



   That's what we're doing here right now. The sketches

   I published don't speak to how the EXP-Bus will be

   'jeeped' (Old television vernacular for modifying

   a piece of equipment to some new task not offered

   by the designers) into the spirit and intent of

   the new Z-figure. Let's assume for the moment that

   EXP-Bus is not present. The sketches are not 

   a "Z-figure for EXP-Buses" . . . it's a new architecture

   is a stand alone recipe for success crafted from

   rudimentary ingredients. Making a practical

   adaptation of an EXP-Bus to the task is a separate

   activity we can tackle after the cake is in the oven.

   It's just 'frosting' . . . 



 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 5:52 am Post subject: EXP 2 Bus workaround

At 05:51 AM 10/26/2013, you wrote:

 	  Quote: 	
		  



FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work 

fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes 

up no more than 2 psi. even with my somewhat restrictive 5/16" 

return plumbing. Some fellows run both pumps for landing and 

takeoff. Selecting both on is the first thing we do if the engine is 

not running properly. Injector flow increases with the square root 

of pressure so that is not an issue since normal EFI pressures run 

around 38 psi above manifold pressure.


	


   Good data sir. Thanks!



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 5:58 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		    	  Quote: 	
		    Is anyone flying this combination of hardware? How much does

   IAS need to be reduced to stop a windmilling prop? The few

   times I stopped the prop on a TC airplane I had to really

   work at it. The idea that one needs access to a starter

   motor in flight is mostly without foundation. This is a

   fact you need to resolve for your harware combination. 	


 Bob...I'm getting some data on this. 	


     Does your engine feature a PSRU? If so, does it

     include a spag-clutch on the propeller shaft

     for mitigation of rotational vibration stresses

     on the gearbox?



     If so, then the prop windmills at all speeds and

     does not back-drive the engine. But in any case,

     pushing a starter button with the notion that a

     starter will respond assumer is ales a battery contactor

     is closed and FAT-wire power is also available to

     the starter. Starter button is not an E-bus load.



 

   Bob . . .    [quote][b]

livingjw(at)earthlink.net
Guest

Posted: Sat Oct 26, 2013 5:59 am Post subject: EXP 2 Bus workaround

On this list we have seen examples of       internal battery failures and wire connector failures and switch       failures. Granted that these things typically have low failure       rates, but if they happen, you have no backup. By going with one       battery and not knowing if the alternator will back you up you       have elevated these failures to the status of a prop, engine, wing       or control surface failure. 

       

       John

       

       

       

       

       

       

       

       

       On 10/26/2013 9:03 AM, Robert L. Nuckolls, III wrote:

     

     [quote]       At 11:44 PM 10/25/2013, you wrote:

        	  Quote: 	
		  I am still stumped as         to why you         would recommend one battery. I could agree if the one alternator         is         guaranteed to work without the battery in the circuit, but not         without         that backup. You must think batteries are much more reliable         than I do.         

       	
       

         Oky, let's ex[;pre that premise. What in your

         studies and/or experience with batteries leads

         you to believe that they demonstrate a risky,

         in-service failure rate?

              Before you add a second battery, are there things

         that can be done to mitigate your concerns and

         reduce in-service failures to acceptable risk

         levels?

       

         Recall that the original premise for dual batteries

         had nothing to do with worries for battery failure

         and everything to do with walling off known quantities

         of energy off to do separate tasks . . . where one

         of those tasks was critical to continued flight:

         keep the engine running. The two battery concept was

         never intended to be a hedge against the failure

         of one battery.

       

                

             Bob . . .                   	  Quote: 	
		  

	
       [b]

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 6:45 am Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 3:51 AM, Ken wrote:

 	  Quote: 	
		  FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes up no more than 2 psi. even with my somewhat restrictive 5/16" return plumbing. Some fellows run both pumps for landing and takeoff. Selecting both on is the first thing we do if the engine is not running properly. Injector flow increases with the square root of pressure so that is not an issue since normal EFI pressures run around 38 psi above manifold pressure.

	




Thanks Ken...I stand corrected...my engine at 1.8 L is a tad smaller than your Legacy...it's set up w/ 3/8" fuel supply line and a 1/4" return line using R9 injector hose aft of my firewall. I believe the fuel pressure regulator has been set to factor in whatever restrictive backpressure the 1/4" return line contributes.

Ron Carr at RAM Performance sez my engine's fuel pressure will be 38 psi at idle and rise to 43 psi at WOT. 

(I have not discussed the dual pump issues w/ him because he sells his engines with only one pump.)

Fred

 [quote][b]

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Sat Oct 26, 2013 6:58 am Post subject: EXP 2 Bus workaround

Fred, Bob, et al, I have no dog in this fight, I've just been following the discussion but I've got to ask; with all these workarounds you're doing to make the EXPBus work with your airplane's systems, what is it buying you? The Spruce description of the EXPBus is all about easy squeazy installation and time savings, yet you're being forced into more and more redesign and adaptation in order to make it work for you. I realize that you're a long way down the road with this thing but have you thought about just grabbing a clean sheet of paper and sending the EXPBus to eBay? 



Rick Girard



On Sat, Oct 26, 2013 at 8:58 AM, John W Livingston <livingjw(at)earthlink.net (livingjw(at)earthlink.net)> wrote:

  	  Quote: 	
		                     On this list we have seen examples of       internal battery failures and wire connector failures and switch       failures. Granted that these things typically have low failure       rates, but if they happen, you have no backup. By going with one       battery and not knowing if the alternator will back you up you       have elevated these failures to the status of a prop, engine, wing       or control surface failure. 

       

       John

       

       

       

       

       

       

       

       

       On 10/26/2013 9:03 AM, Robert L. Nuckolls, III wrote:

     



      	  Quote: 	
		         At 11:44 PM 10/25/2013, you wrote:

        	  Quote: 	
		  I am still stumped as         to why you         would recommend one battery. I could agree if the one alternator         is         guaranteed to work without the battery in the circuit, but not         without         that backup. You must think batteries are much more reliable         than I do.         

       	
       

         Oky, let's ex[;pre that premise. What in your

         studies and/or experience with batteries leads

         you to believe that they demonstrate a risky,

         in-service failure rate?

              Before you add a second battery, are there things

         that can be done to mitigate your concerns and

         reduce in-service failures to acceptable risk

         levels?

       

         Recall that the original premise for dual batteries

         had nothing to do with worries for battery failure

         and everything to do with walling off known quantities

         of energy off to do separate tasks . . . where one

         of those tasks was critical to continued flight:

         keep the engine running. The two battery concept was

         never intended to be a hedge against the failure

         of one battery.

       

                



             Bob . . .                   	  Quote: 	
		  

	
       	
     

       	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




	




-- 

Zulu Delta

Mk IIIC

Thanks, Homer GBYM

It isn't necessary to have relatives in Kansas City in order to be unhappy.

   - Groucho Marx

 

  [quote][b]

_________________
The smallest miracle right in front of you is enough to make you happy....

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 7:42 am Post subject: EXP 2 Bus workaround

At 09:57 AM 10/26/2013, you wrote:

  	  Quote: 	
		  Fred, Bob, et al, I have no dog in this fight, I've just been following the discussion but I've got to ask; with all these workarounds you're doing to make the EXPBus work with your airplane's systems, what is it buying you? The Spruce description of the EXPBus is all about easy squeazy installation and time savings, yet you're being forced into more and more redesign and adaptation in order to make it work for you. I realize that you're a long way down the road with this thing but have you thought about just grabbing a clean sheet of paper and sending the EXPBus to eBay? 	


   For me, this discussion is NOT an attempt to

   craft a Z-Figures for EXP-Bus. It's a new look

   at Z-19 and other manifestations of two-battery

   installations to explore well reasoned alternatives.



   When and if the new Z-figure makes it to the back

   of the book, then well see if we can fiddle with

   an EXP-Bus to achieve the same architecture crafted

   to design goals.



 

 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 7:46 am Post subject: EXP 2 Bus workaround

At 09:44 AM 10/26/2013, you wrote:



 	  Quote: 	
		  On Oct 26, 2013, at 3:51 AM, Ken wrote:



>FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy 

>work fine with a oem regulator all of 1990 to 1994 vintage. 

>Pressure goes up no more than 2 psi. even with my somewhat 

>restrictive 5/16" return plumbing. Some fellows run both pumps for 

>landing and takeoff. Selecting both on is the first thing we do if 

>the engine is not running properly. Injector flow increases with 

>the square root of pressure so that is not an issue since normal 

>EFI pressures run around 38 psi above manifold pressure.



Thanks Ken...I stand corrected...my engine at 1.8 L is a tad smaller 

than your Legacy...it's set up w/ 3/8" fuel supply line and a 1/4" 

return line using R9 injector hose aft of my firewall. I believe the 

fuel pressure regulator has been set to factor in whatever 

restrictive backpressure the 1/4" return line contributes.



Ron Carr at RAM Performance sez my engine's fuel pressure will be 38 

psi at idle and rise to 43 psi at WOT.


	


    The question to be answered for evolving this

    new architecture is whether or not having two

    pumps on at the same time represents any kind

    of hazard.



    The second pump is included to mitigate the

    failure of the first pump. The first pump is

    presently powered any time the MP-Bus is hot.

    If the pump works, then the second pump is

    not needed. If the first pump fails, the second

    pump is available. At no time has anyone

    suggested that the pumps should be operated

    simultaneously on purpose.



   Bob . . .

klehman(at)albedo.net
Guest

Posted: Sat Oct 26, 2013 7:49 am Post subject: EXP 2 Bus workaround

>   Is anyone flying this combination of hardware? How much does

 >   IAS need to be reduced to stop a windmilling prop? The few

 >   times I stopped the prop on a TC airplane I had to really

 >   work at it. The idea that one needs access to a starter

 >   motor in flight is mostly without foundation. This is a

 >   fact you need to resolve for your harware combination.



Somewhat different hardware but indicative.  With a 1.92 gear ratio and 

a 3 bladed 72" non-tapered warp prop my ej22 windmills down to below 40 

knots. However if I do intentionally stop it (difficult to do with a 

best glide speed of about 65 knots), a 120 knot dive is insufficient to 

get a restart. More interesting was that unlike many airplanes, my Rebel 

has about the same glide ratio whether windmilling or stopped which 

surprised me. Obviously I do not have one of the sprag clutch type 

arrangements that have been so troublesome...



Ken

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 7:54 am Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 7:57 AM, Richard Girard wrote:

 	  Quote: 	
		  Fred, Bob, et al, I have no dog in this fight, I've just been following the discussion but I've got to ask; with all these workarounds you're doing to make the EXPBus work with your airplane's systems, what is it buying you? The Spruce description of the EXPBus is all about easy squeazy installation and time savings, yet you're being forced into more and more redesign and adaptation in order to make it work for you. I realize that you're a long way down the road with this thing but have you thought about just grabbing a clean sheet of paper and sending the EXPBus to eBay? 	




Good question Rick...and one I've asked myself many times. My answer has been that I'll chuck the EXP Bus when I reach the conclusion that doing so will solve more problems than it creates. I'm still a long way from that. 

Your first question..."what is it buying you?"...is an even better question, and I regret that I was simply too ignorant to read between the lines of the marketing hype...I confess to have been dazzled by the EXP's obvious complexity (to what end?) and my belief that "I guess I need to buy one of these, cause I sure wouldn't want to trust myself to build one".

As I presently understand things, the EXP can serve as my main power distribution bus and provides circuits which can be used to power an engine bus (or Motive Power Bus, to use Bob's new term) and an endurance bus, both of which want to have alternate power feeds direct from the battery. 

All this seems fine and doable without making circuitry changes within the EXP, something I'm loath to do, primarily because of my inexperience and unfamiliarity w/ things electronic.

I can only commend Bob for his patience with me,

Fred

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 7:58 am Post subject: EXP 2 Bus workaround

At 08:58 AM 10/26/2013, you wrote:

 	  Quote: 	
		  On this list we have seen examples of internal battery failures and 

wire connector failures and switch failures. Granted that these 

things typically have low failure rates, but if they happen, you 

have no backup. By going with one battery and not knowing if the 

alternator will back you up you have elevated these failures to the 

status of a prop, engine, wing or control surface failure.


	


   Let's concentrate on battery failures . . . and

   the failure of components that hook that battery

   to ground and the contactor stud.



   What was the nature of failures internal to the

   battery? What was the nature of failure for

   any wires/connectors for which you have data?



   Yes. Propellers have flown off the end of crankshafts,

   wheels have departed their axles, elevator push-rods

   have become disconnected. We read about and ponder these

   events . . . did any one of these FEMA prompt recommendations

   for dual engines, an extra landing gear strut and wheel

   or perhaps splitting the elevator into two halves with

   independent pushrods?



   The rational response to such stories is to move

   avoidance for root cause into prominent positions

   for attention to detail. I've observed many

   times in these writings that the greatest risk

   to the airborne mission is the human element; a

   risk for missing/ignoring critical fundamentals.



   Can we deduce what attention to detail is needed

   to make a battery as reliable as your prop bolts?



   Bob . . .

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 8:08 am Post subject: EXP 2 Bus workaround

Bob...you asked:



 	  Quote: 	
		   Is anyone flying this combination of hardware? 	




	I asked a pal flying a RAM Sube powered Europa the following questions:

 	  Quote: 	
		   	  Quote: 	
		  In your bird, have you ever stopped your engine in flight?

.If so, did the prop stop or windmill?

If the prop stopped, how did you get it spinning again?

Can you spin your starter w/ the Master Switch off?

If not, would you like to be able to?



	
	




 	...and got this reply...not much help unfortunately.

	Fred



 	  Quote: 	
		  Hi Fred - no I've never stopped it.  I thought about flying to an aiport 40 miles north that has an 12000 ft runway and climb to 10000 ft at 6 AM when no traffic was around and turn it off but haven't done it yet.

 

I can turn everything off but the fuel pumps and ignition and the engine will run but I never thought of whether the starter

would work - duh!!  

 

I'll have to check that and get back to you.  I need to see if the trim works with everything turned off as well.  I'm wondering if with the ac trimmed for cruise whether I would still have enough elevator for the landing flare.

 

 

XXXX

 

From: fklein(at)orcasonline.com (fklein(at)orcasonline.com)

Subject: a Europa query

Date: Fri, 25 Oct 2013 22:04:53 -0700

To: XXXX(at)hotmail.com (gcrowder2(at)hotmail.com)



XXXX



In your bird, have you ever stopped your engine in flight?

.If so, did the prop stop or windmill?

If the prop stopped, how did you get it spinning again?

Can you spin your starter w/ the Master Switch off?

If not, would you like to be able to?





Sorry for all the questions...they are a consequence of an online conversation I'm having with Bob Nuckolls at AeroElectric-list...excerpt below:





 	  Quote: 	
		   	  Quote: 	
		  >  ( Starter can control from main bus.



                 True...and...w/ my particular combination of engine, reduction ratio, propeller, and aircraft performance envelope, although I THINK that with engine out, prop would windmill sufficient to restart engine, if Master switch was OFF, I'd like to be able to spin the starter...that was the INTENT of what the diagram shows...What do you think?...I'm unsure as to whether or not the wiring diagram allows for that to happen. 	


  Is anyone flying this combination of hardware? How much does

  IAS need to be reduced to stop a windmilling prop? The few

  times I stopped the prop on a TC airplane I had to really

  work at it. The idea that one needs access to a starter

  motor in flight is mostly without foundation. This is a

  fact you need to resolve for your harware combination. 

	




Thanks once again for your help,

Fred

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Sat Oct 26, 2013 8:59 am Post subject: EXP 2 Bus workaround

On Oct 26, 2013, at 8:49 AM, Ken wrote:

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



 	  Quote: 	
		     Is anyone flying this combination of hardware? How much does

   IAS need to be reduced to stop a windmilling prop? The few

   times I stopped the prop on a TC airplane I had to really

   work at it. The idea that one needs access to a starter

   motor in flight is mostly without foundation. This is a

   fact you need to resolve for your harware combination.


	


Somewhat different hardware but indicative.  With a 1.92 gear ratio and a 3 bladed 72" non-tapered warp prop my ej22 windmills down to below 40 knots. However if I do intentionally stop it (difficult to do with a best glide speed of about 65 knots), a 120 knot dive is insufficient to get a restart. More interesting was that unlike many airplanes, my Rebel has about the same glide ratio whether windmilling or stopped which surprised me. Obviously I do not have one of the sprag clutch type arrangements that have been so troublesome...

	




Ken...interesting...my PSRU ratio is 1.9 to 1.0 and I too do not have a sprag clutch...Fred



 [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Oct 26, 2013 9:10 am Post subject: EXP 2 Bus workaround

 	  Quote: 	
		    	  Quote: 	
		    	  Quote: 	
		  Can you spin your starter w/ the Master Switch off? 	
	
	


     Why would you want access to the

     starter with the master switch off?

     Under what conditions would you first

     have the switch off and then find that

     the engine has assumed a condition that

     needs encouragement to get running again?

     Assuming that the engine is at risk for

     doing such a thing, what prevents you

     from turning the master switch back on?



 

 

   Bob . . .    [quote][b]

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