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hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Tue Jan 29, 2008 8:31 am Post subject: Z Diagram Questions

Hello,



I'm an RV10 builder with a bunch of questions regarding the Z diagrams. Sidebar: I really appreciate the obvious amount of work required to put these together. I'd hate to think how much time and $$ would be wasted rolling my own electrical system without leveraging this resource.



Cheers,

Jay



* I have in mind using two 17AH batteries to be mounted in the battery mount back behind the baggage compartment. What's connected from here is up for grabs. 



* The current plan is to use one electronic ignition and one traditional mag with glass panel (and a few steam gauge backups). Others have done this successfully, so this shouldn't be breaking too much new ground. I believe my choices are pointing to using either Z-14 (Dual Battery/Alternator/Split Bus) or  Z-19RB (Dual Battery/Single Alt/Rear Batt). 



* Z-14 is obviously way more expensive, has more moving parts and appears to be overkill. However, the Z-19RB (5/4/07) has shows 5 engine/dc power switches as compared to 3 required for Z-14. In addition,  Z-19RB appears to use an obsolete/unavailable part (ack!) AEC9005-101 low voltage module. I found another Z-19 cousin while pawing around called FOLDOUT4.DWG. This one uses the LR-3 and appears to be a bit more simple compared to the Z-19RB. Is Z-19RB "dated"? 



Q1: Z-14 diagram (rev 5/9/06) strangeness... Both AUX & Main contactors are shown with 4AWG in and out of the primary terminals. Strangely, the Crossfeed contactor has 2AWG out (to Main Batt Contactor) which then uses 4AWG going forward to the Starter contactor. 2AWG is shown from Starter contactor to Starter. 



 	  Quote: 	
		  >> It seems like 2AWG should be used consistently (without mixing 4AWG in series) to carry high  current loads forward? The REAR Battery contactors are close to batteries, but the Crossfeed contactor is ~15 feet away on the engine side of the firewall close to the Starter contactor. Was Z-14 orginally created assuming forward battery placement?


	


Q2: General ALT fuse question: What's the rationale behind how to size ANL fuses (maybe max amps - 10 or something)? The fuse protects the wire, right? So are we assuming the purpose of ANL is to protect against possible runaway ALT operation? Under what conditions might this scenario occur? Are ANL slow blow fuses? If so, why would one use those in general? Note 10 didn't go into enough detail for inquiring minds.



Q3: Some Z diagrams show the LR-3 ALT Controller "Volts Warn" light with a push-to-test switch. I would think the lamp would light whenever batt power is applied to the LR-3, but the ALT is not yet running. Is PTT really necessary (it's yet another switch)?



Q4: A number of Z diagrams show an inline current sensing resistor (w/ voltage output). Are builders exposing voltmeters on their panel, plumbing volts to EFIS display or something  else? I haven't seen lots of panels with voltmeters hanging off them except in spam cans... Knowing current state is obviously a great indicator of ALT health.



Q5: What's your opinion on solid state (i.e. MOSFET) contactors? Are they ready for prime time? Aircraft Spruce lists one on their website, but no pricing is shown (I smell problems).  How long should steam guage contactors last under normal operation? http://www.aircraftspruce.com/catalog/elpages/superSwitch.php



Q6: Why do B&C alternators all use external regulators? Are there safety and/or MTBF factors to consider as opposed to internally regulated units? The external LR-3 really add to the total $$.



 [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Tue Jan 29, 2008 7:03 pm Post subject: Z Diagram Questions

At 08:24 AM 1/29/2008 -0800, you wrote:



 	  Quote: 	
		  Hello,



I'm an RV10 builder with a bunch of questions regarding the Z diagrams. 

Sidebar: I really appreciate the obvious amount of work required to put 

these together. I'd hate to think how much time and $$ would be wasted 

rolling my own electrical system without leveraging this resource.



Cheers,

Jay



* I have in mind using two 17AH batteries to be mounted in the battery 

mount back behind the baggage compartment. What's connected from here is 

up for grabs.


	


   Why two?

 	  Quote: 	
		  * The current plan is to use one electronic ignition and one traditional 

mag with glass panel (and a few steam gauge backups). Others have done 

this successfully, so this shouldn't be breaking too much new ground. I 

believe my choices are pointing to using either Z-14 (Dual 

Battery/Alternator/Split Bus) or Z-19RB (Dual Battery/Single Alt/Rear Batt).



* Z-14 is obviously way more expensive, has more moving parts and appears 

to be overkill. However, the Z-19RB (5/4/07) has shows 5 engine/dc power 

switches as compared to 3 required for Z-14. In addition,  Z-19RB appears 

to use an obsolete/unavailable part (ack!) AEC9005-101 low voltage module. 

I found another Z-19 cousin while pawing around called FOLDOUT4.DWG. This 

one uses the LR-3 and appears to be a bit more simple compared to the 

Z-19RB. Is Z-19RB "dated"?


	




   First, consider Z-13/8 with one battery and tell us how

   it falls short of a perceived requirement. If you're

   planning any form of non-traditional aircraft ignition,

   consider a p-mag.

 	  Quote: 	
		  Q1: Z-14 diagram (rev 5/9/06) strangeness... Both AUX & Main contactors 

are shown with 4AWG in and out of the primary terminals. Strangely, the 

Crossfeed contactor has 2AWG out (to Main Batt Contactor) which then uses 

4AWG going forward to the Starter contactor. 2AWG is shown from Starter 

contactor to Starter.


	


   Z-14 is not appropriate for 99% of the OBAM projects

   under construction . . .



 	  Quote: 	
		  Q2: General ALT fuse question: What's the rationale behind how to size ANL 

fuses (maybe max amps - 10 or something)? The fuse protects the wire, 

right? So are we assuming the purpose of ANL is to protect against 

possible runaway ALT operation? Under what conditions might this scenario 

occur? Are ANL slow blow fuses? If so, why would one use those in general? 

Note 10 didn't go into enough detail for inquiring minds.


	


   Fuses protect wires only and have no value in

   mitigating a runaway alternator condition. A runaway

   alternator is generally incapable of opening the

   b-lead protection under any conditions.

 	  Quote: 	
		  Q3: Some Z diagrams show the LR-3 ALT Controller "Volts Warn" light with a 

push-to-test switch. I would think the lamp would light whenever batt 

power is applied to the LR-3, but the ALT is not yet running. Is PTT 

really necessary (it's yet another switch)?



Q4: A number of Z diagrams show an inline current sensing resistor (w/ 

voltage output). Are builders exposing voltmeters on their panel, plumbing 

volts to EFIS display or something else? I haven't seen lots of panels 

with voltmeters hanging off them except in spam cans... Knowing current 

state is obviously a great indicator of ALT health.


	


   Only if you know how to interpret what it

   displays. See chapter on instrumentation.

 	  Quote: 	
		  Q5: What's your opinion on solid state (i.e. MOSFET) contactors? Are they 

ready for prime time? Aircraft Spruce lists one on their website, but no 

pricing is shown (I smell problems).  How long should steam guage 

contactors last under normal operation?


	


 	  Quote: 	
		  <http://www.aircraftspruce.com/catalog/elpages/superSwitch.php>http://www.aircraftspruce.com/catalog/elpages/superSwitch.php




	


   Don't know how to answer this. I've ssen them last

   20 years with no problems and I have some rental

   airplanes that got replacements in less than 5 years.

   The best answer is that return on investment for these

   devices is good. A failure tolerant architecture

   makes contactor failure a cost of ownership issue

   and not a flight safety issue. That's what I would

   use if I were building.



   There are no mosfet contactors suited for both

   loading and charging a battery . . . mosfet

   devices are decidedly one-way streets.



 	  Quote: 	
		  Q6: Why do B&C alternators all use external regulators? Are there safety 

and/or MTBF factors to consider as opposed to internally regulated units? 

The external LR-3 really add to the total $$.


	


   This is discussed at length in the archives, on

   the website articles and chapters in the 'Connection.



   At present, there is no practical way to make an

   internally regulated alternator function in

   the same manner as externally regulated machines

   have and still to perform in aircraft. I'm working

   on it but my 20-hour a week consulting task has

   morphed into another career! See:



http://aeroelectric.com/articles/Adapting_IR_Alternators_to_Aircraft.pdf

   Bob . . .

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Tue Jan 29, 2008 10:11 pm Post subject: Z Diagram Questions

* I have in mind using two 17AH batteries to be mounted in the battery   mount back behind the baggage compartment. What's connected from here is   up for grabs.   	  

   Why two?  

 	  Quote: 	
		  >> Assumming dead alternator... The goal is for battery (or batteries) to provide adequate power to avionics & ignition system to safely complete flight. Hopefully, the total available amp-hour capacity exceeds available fuel supply. The notion is that two batteries provide redundancy if one proves incapable of providing adequate performance. Rotating one out at each annual reduces dud factor.


	


<snip>

  

* Z-14 is obviously way more expensive, has more moving parts and appears   to be overkill. However, the Z-19RB (5/4/07) has shows 5 engine/dc power switches as compared to 3 required for Z-14. In addition,  Z-19RB appears   to use an obsolete/unavailable part (ack!) AEC9005-101 low voltage module.   I found another Z-19 cousin while pawing around called FOLDOUT4.DWG. This one uses the LR-3 and appears to be a bit more simple compared to the   Z-19RB. Is Z-19RB "dated"?   	  

  First, consider Z-13/8 with one battery and tell us how  it falls short of a perceived requirement. If you're planning any form of non-traditional aircraft ignition,   consider a p-mag.  

 	  Quote: 	
		  >> Z-13 is an attractive setup. However, my understanding is that p-mag devices aren't available for 6 cylinder (e.g. Lycoming 540) engines. I thought they were only used on 4 cylinder ones. Therefore, I have not considered Z-13 as a viable option. Z19RB still seems to fit.


	


Q1: Z-14 diagram (rev 5/9/06) strangeness... Both AUX & Main contactors   are shown with 4AWG in and out of the primary terminals. Strangely, the   Crossfeed contactor has 2AWG out (to Main Batt Contactor) which then uses   4AWG going forward to the Starter contactor. 2AWG is shown from Starter contactor to Starter.   	  

   Z-14 is not appropriate for 99% of the OBAM projects  under construction . . .  

 	  Quote: 	
		  >> It is overkill. What are the characteristics of the 1% that Z-14 would be good for? Dual electronic ignition w/ EFIS-only avionics seems a likely candidate.


	


Q2: General ALT fuse question: What's the rationale behind how to size ANL   fuses (maybe max amps - 10 or something)? <snip>  

 	     Fuses protect wires only and have no value in  mitigating a runaway alternator condition. A runaway  alternator is generally incapable of opening the  b-lead protection under any conditions.  



 	  Quote: 	
		  >> Okay, but what size ANL is appropriate for 60A alternator? Something less than 60A ANL? I can't imagine ever pulling anywhere close to 60A total. Dumb question - Does a 60A alternator put out 60A continuously or does its output vary depending upon other factors?


	






      [quote][b]

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Wed Jan 30, 2008 5:44 am Post subject: Re: Z Diagram Questions

Please ignore my previous post regarding ALT output current. I believe the regulator samples voltage and then controls Field lead to make generator (ALT) output current up to the rated capacity of the device.



Jay

nuckolls.bob(at)cox.net
Guest

Posted: Wed Jan 30, 2008 6:21 pm Post subject: Z Diagram Questions

At 10:07 PM 1/29/2008 -0800, you wrote:

 	  Quote: 	
		  * I have in mind using two 17AH batteries to be mounted in the battery 

mount back behind the baggage compartment. What's connected from here is 

up for grabs.

Why two?

 >>> Assumming dead alternator... The goal is for battery (or batteries) 

 to provide adequate power to avionics & ignition system to safely 

 complete flight. Hopefully, the total available amp-hour capacity exceeds 

 available fuel supply. The notion is that two batteries provide 

 redundancy if one proves incapable of providing adequate performance. 

 Rotating one out at each annual reduces dud factor.

   If you have a vacuum pump pad open, an 8A

   alternator is a whole lot lighter than

   a second 17 a.h. battery, has indefinite

   service life and unlimited energy for

   continued flight.

 	  Quote: 	
		  <snip>

* Z-14 is obviously way more expensive, has more moving parts and appears 

to be overkill. However, the Z-19RB (5/4/07) has shows 5 engine/dc power 

switches as compared to 3 required for Z-14. In addition, Z-19RB appears 

to use an obsolete/unavailable part (ack!) AEC9005-101 low voltage module. 

I found another Z-19 cousin while pawing around called FOLDOUT4.DWG. This 

one uses the LR-3 and appears to be a bit more simple compared to the 

Z-19RB. Is Z-19RB "dated"?

   Z-19 is for electrically dependent automotive

   conversions that CANNOT have a second alternator.

 	  Quote: 	
		  First, consider Z-13/8 with one battery and tell us how it falls short of 

a perceived requirement. If you're planning any form of non-traditional 

aircraft ignition,

consider a p-mag.

 >>> Z-13 is an attractive setup. However, my understanding is that p-mag 

 devices aren't available for 6 cylinder (e.g. Lycoming 540) engines. I 

 thought they were only used on 4 cylinder ones. Therefore, I have not 

 considered Z-13 as a viable option. Z19RB still seems to fit.

   No. Z-13/8 can be used with ANY combination of ignition

   systems. For the lightest weight, lowest cost of ownership

   and highest reliability, Z-13/8 with one battery is your

   best choice.

 	  Quote: 	
		  Q1: Z-14 diagram (rev 5/9/06) strangeness... Both AUX & Main contactors 

are shown with 4AWG in and out of the primary terminals. Strangely, the 

Crossfeed contactor has 2AWG out (to Main Batt Contactor) which then uses 

4AWG going forward to the Starter contactor. 2AWG is shown from Starter 

contactor to Starter.

Z-14 is not appropriate for 99% of the OBAM projects under construction . . .

 >>> It is overkill. What are the characteristics of the 1% that Z-14 

 would be good for? Dual electronic ignition w/ EFIS-only avionics seems a 

 likely candidate.

   No. A Lancair IVP with full up IFR panel both

   sides and intended to be used in a manner that

   pushes the comfort zone for all weather flight.

   Since that drawing was published, I've had only

   3 or 4 readers who were building that kind of

   airplane with that kind of mission.

 	  Quote: 	
		  Q2: General ALT fuse question: What's the rationale behind how to size ANL 

fuses (maybe max amps - 10 or something)? <snip>

Fuses protect wires only and have no value in mitigating a runaway 

alternator condition. A runaway alternator is generally incapable of 

opening the b-lead protection under any conditions.

 >>> Okay, but what size ANL is appropriate for 60A alternator? Something 

 less than 60A ANL? I can't imagine ever pulling anywhere close to 60A 

 total. Dumb question - Does a 60A alternator put out 60A continuously or 

 does its output vary depending upon other factors?

   Look at the specs for an ANL published at:

http://www.aeroelectric.com/Mfgr_Data/Fuses_and_Current_Limiters/Bussman/ANL_Specs.pdf

   An ANL35 would carry the full output of a 60A alternator

   indefinitely. ANL devices are not fuses in the classic

   sense. They're designed to protect against hard faults

   against batteries (read 1000+ amps). They don't have to

   be calibrated with the same precision as the classic fuse.

   It's easy to find an 60, use that.

   Bob . . .

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Thu Jan 31, 2008 2:22 pm Post subject: Re: Z Diagram Questions

f you have a vacuum pump pad open, an 8A

alternator is a whole lot lighter than

a second 17 a.h. battery, has indefinite

service life and unlimited energy for

continued flight.



>> I do have one and I will consider this option. 



Z-19 is for electrically dependent automotive

conversions that CANNOT have a second alternator. 



>> That's fairly obvious once you understand what ECU and EFI acronyms mean... However, the diagram nicely showed a rear battery mount just like the RV10 requires (it's nose heavy). I had a lot of confusion until someone pointed out to me that, in general, Z diagrams were written from the view point of airplanes that use front-mounted batteries. It's not always easy to tell which is which as "RB" only appears in the -19 as far as it could see.



Z-13/8 can be used with ANY combination of ignition

systems. For the lightest weight, lowest cost of ownership

and highest reliability, Z-13/8 with one battery is your

best choice. 



>> I agree in principle that this would be the best choice. However - I spoke with the P-Mag guys and the 6 cylinder version is -not- a shipping product (or anytime soon either). Since vaporware isn't a good power source, I'll build my electrical system to not preclude this as a future upgrade.

A Lancair IVP with full up IFR panel both

sides and intended to be used in a manner that

pushes the comfort zone for all weather flight.

Since that drawing was published, I've had only

3 or 4 readers who were building that kind of

airplane with that kind of mission. 



>> Maybe, but I'm willing to bet there are more than a couple of RV10 builders considering this route. Are you guys out there lurking? 

Look at the specs for an ANL published at:

http://www.aeroelectric.com/Mfgr_Data/Fuses_and_Current_Limiters/Bussman/ANL_Specs.pdf



>> Thanks. It's a bit overwhelming how many documents are available. I'm not complaining as it's better to know the information must be out there than to simply "guess" and be sorry later!

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Thu Jan 31, 2008 2:36 pm Post subject: Re: Z Diagram Questions

One more question... The Z-19RB battery location is the same as for the RV-10. Do you see any real advantage of running a #2AWG ground forward to the forest of tab in a metal airplane rather than grounding locally? There's plenty of conduit space space in my fuse, but would rather save the weight as #2 is pretty heavy. I'm planning on running #2AWG forward to the starter...



Thanks,

Jay

nuckolls.bob(at)cox.net
Guest

Posted: Fri Feb 01, 2008 6:09 am Post subject: Z Diagram Questions

At 02:36 PM 1/31/2008 -0800, you wrote:



 	  Quote: 	
		  



One more question... The Z-19RB battery location is the same as for the 

RV-10. Do you see any real advantage of running a #2AWG ground forward to 

the forest of tab in a metal airplane rather than grounding locally? 

There's plenty of conduit space space in my fuse, but would rather save 

the weight as #2 is pretty heavy. I'm planning on running #2AWG forward to 

the starter...



Thanks,

Jay


	


   See 

http://www.aeroelectric.com/articles/Battery_Grounds/Battery_Grounds.html



   Bob . . .

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Fri Feb 01, 2008 6:36 am Post subject: Re: Z Diagram Questions

Jay,



I'm using a Z-14 in my RV-10.  I have dual electronic ignitions and an all electric panel (but with 2.25" ASI and ALT for backup).  Given my absolute dependence on having juice flowing, it wasn't that much of a leap from Z-13/20 to Z-14.  I have an electronic ignition on each battery bus and the panel "stuff" is split between the buses.  When I did the allocations to each bus it was with consideration of what would happen "if".  Given that, I can lose one bus in its entirety and still not be sweating even if I'm in the clag.  Granted, if that happens I'll get on the ground and figure it out but it will be with the comfort of being able to pick which airport and approach I'll use.



Looking at actual measured panel loads, it would be no big deal to downsize from a 60A main alternator to a 40A and the vacuum pad alternator from 20A to 8A.  That would probably more than offset the additional cost/weight of the second battery, 2 contactors and related wire while still retaining huge redundancy.



Bob #40105

nuckolls.bob(at)cox.net
Guest

Posted: Fri Feb 01, 2008 6:44 am Post subject: Z Diagram Questions

At 02:22 PM 1/31/2008 -0800, you wrote:



 	  Quote: 	
		  



f you have a vacuum pump pad open, an 8A

alternator is a whole lot lighter than

a second 17 a.h. battery, has indefinite

service life and unlimited energy for

continued flight.



 >> I do have one and I will consider this option.


	


   ??? What consideration of physics and operational

   philosophy prevents you from doing this right

   now? How does a second battery become more attractive

   than an engine driven power source that is lighter,

   performs better (unlimited energy, practically

   zero maintenance) and a fraction of the cost of

   ownership?

 	  Quote: 	
		  Z-19 is for electrically dependent automotive

conversions that CANNOT have a second alternator.



 >> That's fairly obvious once you understand what ECU and EFI acronyms 

 mean... However, the diagram nicely showed a rear battery mount just like 

 the RV10 requires (it's nose heavy). I had a lot of confusion until 

 someone pointed out to me that, in general, Z diagrams were written from 

 the view point of airplanes that use front-mounted batteries. It's not 

 always easy to tell which is which as "RB" only appears in the -19 as far 

 as it could see.


	


    You can mount the battery(ies) in the back for ANY

    of the Z-figures. If you're selecting Z-19RB just

    because of where the battery goes, then it's

    not clear that you understand what the z-figures

    are intended to illustrate.

 	  Quote: 	
		  Z-13/8 can be used with ANY combination of ignition

systems. For the lightest weight, lowest cost of ownership

and highest reliability, Z-13/8 with one battery is your

best choice.



 >> I agree in principle that this would be the best choice. However - I 

 spoke with the P-Mag guys and the 6 cylinder version is -not- a shipping 

 product (or anytime soon either). Since vaporware isn't a good power 

 source, I'll build my electrical system to not preclude this as a future 

 upgrade.


	


    Don't understand. Conversations with Emagair have

    nothing to do with your architecture decision.

    ANY electronic ignition including Emags will

    operate happily from any source of 12 volts be

    it one of the z-figures . . . or a 12-v lantern

    battery. If you "agree in principal" which I

    presume is an acknowledgement of value for

    seeking the elegant solution, then what information

    are you working with that makes the less elegant

    solution more attractive?

 	  Quote: 	
		  A Lancair IVP with full up IFR panel both

sides and intended to be used in a manner that

pushes the comfort zone for all weather flight.

Since that drawing was published, I've had only

3 or 4 readers who were building that kind of

airplane with that kind of mission.



 >> Maybe, but I'm willing to bet there are more than a couple of RV10 

 builders considering this route. Are you guys out there lurking? 


	


   Conversations with other RV10 builders have

   nothing to do with your architecture decision.

   What failures do you anticipate and under what

   flight conditions that you now believe Z19RB

   or even Z14 is a better choice than Z13/8?

   This is the discussion that should drive choice of

   architecture.

 	  Quote: 	
		  Look at the specs for an ANL published at:

http://www.aeroelectric.com/Mfgr_Data/Fuses_and_Current_Limiters/Bussman/ANL_Specs.pdf



 >> Thanks. It's a bit overwhelming how many documents are available. I'm 

 not complaining as it's better to know the information must be out there 

 than to simply "guess" and be sorry later!


	


   But that illustrates my whole point. There is

   a wealth of published data out there to help you

   make considered decisions based on understanding

   of simple-ideas from which repeatable experiments

   (useful inventions) are assembled. I totally agree

   that "guessing" is bad policy. But "going with

   the flow" may not be much better.



   If it's "overwhelming" to exploit these resources

   to augment your own understanding, then you're

   reduced to decision making by consensus.



   Problem is, those in which you place your trust

   may be no better informed than you choose to

   be. This places you in the position of doing

   what feels best. The result could become the

   equivalent of using a dump truck to tow your

   trash down to the curb or using a back-hoe to

   plant petunias. They DO get the job done but

   the cost of ownership is much larger than it

   needs to be.



   Know that a tiny fraction of bad days in the

   cockpit resulting in bent airplanes and/or

   people have root causes in electrical system

   problems. The vast majority of those events

   that ARE unhappy could be mitigated if not

   eliminated a little preventative maintenance

   or improved understanding. Virtually all of

   the dark-n-stormy night stories I read and

   accidents I've investigated revealed severe

   lack of understanding . . . a condition that

   is the EASIEST to avoid and MOST likely to

   have reduced or even prevented the scenario

   from going to it's unpleasant conclusion.



   Hundreds of thousands of TC aircraft have been

   successfully flown in the conditions you're

   anticipating for nearly 100 years. This largely

   event free outcome is in spite of being burdened

   with crummy batteries, poor preventative

   maintenance and generators/alternators that

   were not much more robust than the batteries.



   If you take a stock 1970 C-172 and do nothing

   more than add low volts warning and put in

   a PROPERLY MAINTAINED RG battery and top

   of with some understanding of system physics,

   I suggest that virtually ALL the dark-n-stormy

   night stories in which this genre'of electrical

   system has center stage would never have been

   written.



   Now we have alternators that run past TBO

   on engines, second alternators that provide

   unlimited endurance, and the freedom to craft

   architectures that optimize performance while

   suffering any failure of a component. As OBAM

   aircraft builders, we're encouraged to understand

   things about our airplanes that our spam-can-bound

   brothers are NOT required to know.



   This is an opportunity to take out lots of

   weight, cost and $time$ to maintain while boosting

   system reliability to numbers the TC guys

   will be hard pressed to achieve . . . EVER.



   That's what we're all here for. Not a pool of

   consensus in which one simply puts a dip-stick.

   This List is where one can find assistance in

   achieving lowest weight, lowest volume, lowest

   parts count, lowest cost of ownership, and

   highest system reliability based on an OPTIMAL

   combination of simple-ideas and repeatable-

   experiments.



   Overwhelming? Sure . . . we are ALL there

   too at some point in our experiences.



   Bob . . .

MauleDriver(at)nc.rr.com
Guest

Posted: Fri Feb 01, 2008 7:39 am Post subject: Z Diagram Questions

Here is my interpretation of same:

http://www.mykitlog.com/users/display_log.php?user=MauleDriver&project 24&category 155&log=43554&row=12



Thanks Bob.



---

nuckolls.bob(at)cox.net
Guest

Posted: Fri Feb 01, 2008 9:38 am Post subject: Z Diagram Questions

At 06:36 AM 2/1/2008 -0800, you wrote:



 	  Quote: 	
		  

<bob.condrey(at)baesystems.com>



Jay,



I'm using a Z-14 in my RV-10.  I have dual electronic ignitions and an all 

electric panel (but with 2.25" ASI and ALT for backup).  Given my absolute 

dependence on having juice flowing, it wasn't that much of a leap from 

Z-13/20 to Z-14.  I have an electronic ignition on each battery bus and 

the panel "stuff" is split between the buses.  When I did the allocations 

to each bus it was with consideration of what would happen "if".  Given 

that, I can lose one bus in its entirety and still not be sweating even if 

I'm in the clag.  Granted, if that happens I'll get on the ground and 

figure it out but it will be with the comfort of being able to pick which 

airport and approach I'll use.



Looking at actual measured panel loads, it would be no big deal to 

downsize from a 60A main alternator to a 40A and the vacuum pad alternator 

from 20A to 8A.  That would probably more than offset the additional 

cost/weight of the second battery, 2 contactors and related wire while 

still retaining huge redundancy.



Bob #40105


	


    A considered analysis of a repeatable experiment.

    Thank you.



    Bob . . .

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