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Physical construction of Z101 engine bus & battery bus

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 06, 2020 6:55 am Post subject: Physical construction of Z101 engine bus & battery bus

At 08:50 AM 6/6/2020, you wrote:

  	  Quote: 	
		  Could someone please re-post the link to Z101? Thanks. 	


    https://tinyurl.com/yc4r5huy



   Latest iteration on the next revision level.

   I've been sifting through the details and

   I think it's 99% 'clean'.



   I'm also working on a set of notes that

   elaborates on the evolution of concepts

   illustrated.



   I'm kinda 'distracted' with a bathroom

   remodel at the moment but you guys can

   massage this thread . . .



 



 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jun 07, 2020 12:28 pm Post subject: Physical construction of Z101 engine bus & battery bus

At 11:32 AM 6/7/2020, you wrote:

  	  Quote: 	
		  Bob, regarding Z101, it seems that auto conversions like the Honda based Viking and Suzuki based Aeromomentum are becoming more and more popular. These engines are electrically dependent, but they do not lend themselves to a dual alternator setup. I wonder if you would consider developing a Z101-B that utilized dual batteries rather than dual alternators? 	


  Is it not possible/practical to maintain one battery

  such that it is capable of supporting the engine

  in an alternator-out scenario?



  How are the duties of two batteries allocated in what

  I presume is a engine manufacturer's recommendation

  for dual batteries?



 

 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jun 07, 2020 6:51 pm Post subject: Physical construction of Z101 engine bus & battery bus

At 05:26 PM 6/7/2020, you wrote:

  	  Quote: 	
		  I am not speaking to any engine manufacturers recommendation (although the

 Honda Viking manufacturer does recommend two batteries. I just thought

 I was applying logic -- if dual alternatorÂ + battery (triple power source)

 is desirable for electricallyÂ dependent engines, wouldn't that reasoning

 imply that if the second alternator is not practical, a second battery

 could be used as the third power source? I could ask you a similar question:

 Are not two independent power sources (battery and alternator) sufficient

 to meet the needs of the electricallyÂ dependent engine. Obviously you

 saw value in adding the second alternator. Why no value in adding the second battery? 	


   Excellent question.



   It's a problem in energy budgets combined with

   efforts to assure continued airworthiness.



   The airplane cannot do without a battery if

   you're going to have a starter. Depending on

   your planned mission profiles, you will want

   to size the battery (1) for cranking then

   (2) minimum endurance in alternator-out modes.



   This study gave impetus for the creation of

   the endurance bus . . . a fast and predictable

   way to economically tap known quantity of energy

   stored in the battery's chemistry.



   Z13/8 was a small but significant amplification

   of that idea . . . <b>the second alternator's endurance

   had no practical limits.</b> Hence, energy on the chemistry

   just might be held completely in reserve for

   descent and approach to landing.



   Z13/20 (and the aux alternator option on

   Z101) expanded the Z13/8 endurance opportunity

   by a factor of 2.5 or better.



   Okay, suppose the drive pad isn't available.

   We are still charged with identifying and the

   delivering to energy required to comfortably

   terminate a worst-case mission.



   This means that as a part of routine maintenance

   the ship's chemistry needs to be monitored for

   capability. We could certainly store that energy

   on TWO devices but to what advantage? If we're laboring

   under the notion that a battery can suddenly become

   unavailable during one tank of gas, then we have

   to assume that EITHER battery can roll over and

   die . . . okay, how would that failure be 

   annunciated . . . how would remaining energy be

   managed . . . ?



   I think that's the scenario anticipated by the

   folks that crafted that battery manager with a

   full-wave rectifier that -anded- two, completely

   isolated batteries together. Assume the alternator

   has quit and some time later one battery

   craps out. How does the pilot become aware of the

   problem and what kind of energy juggling issues

   are presented when the available energy drops

   to half?  This assuming he really knows that the

   two batteries were performing equally and has

   recently quantified their condition, he now

   has to come up with a new "plan C?" and perhaps

   declare an emergency.



   This scenario first assumes TWO critical failures

   during the consumption of one tank of fuel . . .

   about 3-4 hour window. Part 23 certs don't

   get concerned with dual failures at all.

   Part 25 and heavier will wade into the reliability

   quagmire with mountains of computer generated probability

   studies that get 'worked' on until somebody

   finally sprinkles the holy water and off they

   go.



   Ask Capt. Sullivan what he thinks about

   reliability studies . . .



  https://www.youtube.com/watch?v=HKJ1lIh2Cgk



   So we're left to our own devices which in reality

   are not so bad.



   The short answer is: A diligently maintained

   battery is the most reliable source of energy

   on the airplane. Replacing it when ability

   to store energy drops below some benchmark

   (generally 75 to 80% of new) means that it

   always cranks the engine and will provide a

   quantified option for dealing with alternator

   failure. Two batteries just doubles your

   preventative maintenance labor. Further,

   you need to decide if plan-b can reliably

   depend on the sum total of energy in two

   batteries . . . or will they be sized to

   independently step up to the task? The

   second option calls for 2X the battery

   weight and volume; the first option complicates

   calculations and switching operations for

   carrying out a plan-b that shouldn't ever

   happen. BOTH options still demand good

   preventative maintenance. 



   Just as you KNOW fuel aboard when you launch,

   you also need to know Watt-Hours aboard

   no matter how many batteries you're carrying.



   If you have TWO properly maintained batteries,

   in all likelihood, you'll be carrying around

   $twice$ the hardware with virtually no value

   added to the ship's overall reliability. 



 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jun 08, 2020 7:21 am Post subject: Physical construction of Z101 engine bus & battery bus

At 09:20 PM 6/7/2020, you wrote:

  	  Quote: 	
		  SDSEFI recommends 2 alternators and a battery. If you have a single battery and alternator they recommend an additional battery that is only connected to the ENG BUS for an emergency. The recommended procedure is to charge that battery on the 1st of the month and load test yearly. 	


    Not a particularly definitive battery management

    philosophy. "Charging once a month" whether needed

    or not? "Load test" is not specific . . . what kind

    of load and for discovery of what condition? Internal

    impedance (cranking) or capacity (endurance)?

    How would that knowledge augment the pilot's

    prospects for dealing competently with an alternator

    failure?



    How would these batteries be selected and configured

    in the architecture? What would the plan-b checklist

    look like? Recall that the ultimate goal for crafting

    a failure tolerant architecture is to prevent any

    single failure from becoming an emergency.



    That goal cannot be realized without first knowing the

    ENERGY requirements for the TOTAL constellation

    of hardware necessary to conduct a comfortable termination

    of flight within some ENDURANCE value determined by

    the BUILDER . . . not by some 'authority from afar'

    who will never ride in the airplane.



 

   Bob . . .

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