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Z-19

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nuckolls.bob(at)cox.net
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Posted: Thu Oct 11, 2007 12:05 pm Post subject: Z-19

At 01:53 PM 10/11/2007 -0400, you wrote:



 	  Quote: 	
		  



Bob,

Re: orphaned switch. Well, not exactly orphaned, it just seems randomly

placed for my situation. Specifically I am applying this to a system

with one ECU and two fuel pumps.


	


    Okay, I don't show that in Z-19. Z-19 was crafted to

    address the specifics of an engine that had only

    one fuel pump and one ECU . . . and the builder's

    desire to have two power sources of power for

    that combination.



    Your choice/need to have a second pump is a new

    design goal. How will you become aware of the failure

    of #1 pump in flight? What is the value of being able

    to remove the #2 pump from the system if its pressure

    goes down. Should the pumps be plumbed in series or

    would they be better plumbed in parallel?



    Adding the second pump opens a whole new catalog

    of considerations for how it will be used and

    under what conditions. But I suspect the need to

    shut off a failed #1 pump before bringing the #2

    pump on line is very low if not zero.

 	  Quote: 	
		  I'm on board with expected loads for the ebus and the system routing

stuff. The primary power and secondary power are set. If we loose

primary power, we turn on secondary - no problem.



If pump #1 is burning (figuratively) up and we turn on #2 (already has a

power source), we still have power to pump #1. Ok, you know these

automotive jobs will die quickly with no fuel pump, so if pump #1 fails

we need to turn on pump #2. Not a problem, but there is some delay

there. A more robust way may might be to use a pressure switch to catch

#1 in the event of a failure and flip over to #2 auto-magically.


	


   This pre-supposes some advance ideas of how the pumps

   fail. Every automotive pump electrical failure I've

   encountered caused the pump to draw zero current. The

   siren call of automatic changeover systems is strong . . .

   but they add complexity in both system design but

   operationally (another thing to preflight).

 	  Quote: 	
		  Given all that I would like to isolate #1 should the above events occur.

I would like to add auto failover or at least have the ability to switch

each fuel pump on independent of each other regardless of their

relationship to primary or secondary power.



I agree with your thoughts on limiting the e-bus (in an emergency) to

bare bones equipment, however the diagram showing the primary feed as 7

amps would be inadequate for normal use even if I only used the com

(shown 7 amps). Ok, so all of this can vary - no problem.



I would probably have an issue if under emergency mode I forget to shut

down all but non-essential (probably dark, smoke or some other ugliness)

and flip on my little 10 amp eBus alternate only to find I've just blown

a fuse which I can't replace at the moment (busy flying). I believe I

can adjust that logic and the diagram to fit.


	


   If that fuse powers something absolutely needed for

   comfortable termination of flight and you don't have

   a backup for that system, then replacing the fuse

   is a waste of valuable time. Your system needs to be

   crafted such that the time to shift from Plan-A to

   Plan-B is no longer than what it takes to perceive,

   interpret and react with the throwing of no more than

   a couple of switches. I.e, 5 seconds or less.



   Fiddling with fuses does not fit this operating

   philosophy. Besides, replacing a fuse is most likely

   to blow another fuse and leave you in the same

   position that you were in before you started digging

   around for spare fuses.

 	  Quote: 	
		  Perhaps select items like the MX20 and 530W should be split out onto

another bus to bring the total load down. My setup is a more complex IFR

support. Just more considerations.



There rest of the diagram looks solid (at least from my understanding).

One question? Do I need both the shunt and the ANL in front of the

alternator as shown? My Subaru has the built in regulator, but I would

still like to add an OV protection module.


	


    Your choice. You should have the ANL but the shunt

    can go anywhere or be left out all together. How

    do you plan to make good used of the data that an

    ammeter on the shunt will offer? Is that data useful

    in flight? Is there a way to reduce or eliminate in-flight

    usefulness of that data?



    Bob . . .

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vaughnray(at)bvunet.net
Guest

Posted: Thu Oct 11, 2007 4:49 pm Post subject: Z-19

Bob, 

  

 I have decided on a ULPower 260i engine for my  Europa. It has one ECU and one fuel pump. In my book there is a Z-19 drawing,  but I can't find it on the disk I picked up at your seminar or on your latest  download from your site. Do you suppose that you could email it to me?  Thanks

  

 Vaughn Teegarden

 vaughnray(at)bvunet.net (vaughnray(at)bvunet.net)

  

    [quote][b]

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nuckolls.bob(at)cox.net
Guest

Posted: Sat Oct 13, 2007 3:31 pm Post subject: Z-19

At 08:46 PM 10/11/2007 -0400, you wrote:



 	  Quote: 	
		  Bob,



I have decided on a ULPower 260i engine for my Europa. It has one ECU and 

one fuel pump. In my book there is a Z-19 drawing, but I can't find it on 

the disk I picked up at your seminar or on your latest download from your 

site. Do you suppose that you could email it to me? Thanks



Vaughn Teegarden

<mailto:vaughnray(at)bvunet.net>vaughnray(at)bvunet.net


	


   All of the latest drawings are on the website's

   Page-Per-System library at:



http://www.aeroelectric.com/PPS/ACAD_Architecture_Dwgs/



   for the AutoCAD .dwg format and . . .



http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/



   for the .pdf versions.



   Your heads-up on the CD download is appreciated.

   I forgot to update it. I've loaded Ver 11.1 up at:



http://www.aeroelectric.com/CD

   Bob . . .

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