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Turn on ALT before engine start?

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Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Mon Aug 28, 2006 4:55 am Post subject: Turn on ALT before engine start?

In an airplane equipped with a Continental 0-200, would you want to turn on the ALT switch before engine start, or after?



Thanks!

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brian-av(at)lloyd.com
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Posted: Mon Aug 28, 2006 7:09 am Post subject: Turn on ALT before engine start?

On Aug 28, 2006, at 5:55 AM, Bill Denton wrote:



 	  Quote: 	
		   

 <bdenton(at)bdenton.com>



 In an airplane equipped with a Continental 0-200, would you want to  

 turn on the ALT switch before engine start, or after?


	


It doesn't matter. Do what makes you feel most comfortable.



Brian Lloyd                         361 Catterline Way

brian HYPHEN av AT lloyd DOT com    Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

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nuckollsr(at)cox.net
Guest

Posted: Tue Aug 29, 2006 6:09 am Post subject: Turn on ALT before engine start?

At 05:55 AM 8/28/2006 -0700, you wrote:



 	  Quote: 	
		  



In an airplane equipped with a Continental 0-200, would you want to turn 

on the ALT switch before engine start, or after?


	


   It makes no difference. The arguments for and against

   either philosophy are not backed by good science meaning

   that effects cited as undesirable are so weak as to be

   insignificant.



   This presumes that you have a "controllable" alternator,

   i.e. a separately regulated machine wherein the panel mounted

   alternator switch has control over the alternator's field

   supply.



   The present state of the art for control systems intended

   to bring some measure of protection against failures of

   internally regulated alternators offers a means by which

   the machine can be damaged if inadvertently turned off

   by disconnection of the b-lead which produces a load-dump

   that can be deleterious to the alternator. Many internally

   regulated alternators cannot withstand their own load dumps.



   In these cases, one may turn the alternator ON at any time

   but it's prudent to wait until the engine stops turning to

   turn it OFF.



   In the mean time, know that a control system for internally

   regulated alternators is "in the works" with an achievable

   goal of making the IR alternator behave as if it were

   an externally regulated machine. This will offer the

   OBAM aircraft builder the option of using the stock

   internally regulated alternator as a form-fit-function

   replacement for the traditional externally regulated

   system at a fraction of the cost and without giving

   up functionality or control



   Bob . . .

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

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

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

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Hopperdhh(at)aol.com
Guest

Posted: Tue Aug 29, 2006 6:35 am Post subject: Turn on ALT before engine start?

In a message dated 8/29/2006 10:16:33 A.M. Eastern Daylight Time,  nuckollsr(at)cox.net writes:

  	  Quote: 	
		  In the    mean time, know that a control system for internally

   regulated    alternators is "in the works" with an achievable

   goal of    making the IR alternator behave as if it were

   an externally    regulated machine. This will offer the

   OBAM aircraft builder    the option of using the stock

   internally regulated alternator    as a form-fit-function

   replacement for the traditional    externally regulated

   system at a fraction of the cost and    without giving

   up functionality or control



      Bob . . .

	


 

 I'm really glad to hear that this is in the works, Bob.  Even thought  I am pretty familiar with alternators and regulators, the Van's 60 amp  internally regulated alternator on my airplane is a "black box."  I  have no idea what function the 2 wires that run from the "field" breaker to the  alternator serve.  I believe it is a Nippondenso system.  In the  meantime, do you know of any available documentation which would reveal any  details of its operation?

  

 Dan Hopper

 RV-7A

  

  [quote][b]

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nuckollsr(at)cox.net
Guest

Posted: Tue Aug 29, 2006 7:39 am Post subject: Turn on ALT before engine start?

At 10:34 AM 8/29/2006 -0400, you wrote:



 	  Quote: 	
		  In a message dated 8/29/2006 10:16:33 A.M. Eastern Daylight Time, 

nuckollsr(at)cox.net writes:

    In the mean time, know that a control system for internally

    regulated alternators is "in the works" with an achievable

    goal of making the IR alternator behave as if it were

    an externally regulated machine. This will offer the

    OBAM aircraft builder the option of using the stock

    internally regulated alternator as a form-fit-function

    replacement for the traditional externally regulated

    system at a fraction of the cost and without giving

    up functionality or control



    Bob . . .

I'm really glad to hear that this is in the works, Bob.  Even thought I am 

pretty familiar with alternators and regulators, the Van's 60 amp 

internally regulated alternator on my airplane is a "black box."  I have 

no idea what function the 2 wires that run from the "field" breaker to the 

alternator serve.  I believe it is a Nippondenso system.  In the meantime, 

do you know of any available documentation which would reveal any details 

of its operation?


	


      Not that I've been made privy to. That's a major

      stumbling block for my personal approach to

      systems integration, failure mode effects analysis

      and mitigation.



      I'm going to look at an alternator drive

      stand this weekend that I'm told is a 2+

      hp machine with variable speed drive and

      isn't covered in more barn-bird-crap than

      one would want to wash into the gutters in

      front of my house.



      If this machine can be resurrected, I'll

      be able to characterize the performance of

      any product one wishes to examine. I have

      a couple of alternators here now that came

      from folks on the List that I want to

      put into a Z-11 mock-up and characterize

      their performance and/or failures.



      It seems unlikely that we'll ever be privy

      to detailed inner workings of all the options

      out there. I'll suggest a prudent approach

      that assumes nothing.



      Bob . . .



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

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

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

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nuckollsr(at)cox.net
Guest

Posted: Wed Aug 30, 2006 8:01 am Post subject: Turn on ALT before engine start?

At 09:47 AM 8/30/2006 -0500, you wrote:



 	  Quote: 	
		  Here's a bit of background on my question...



I was considering panel layouts for an OBAM (Experimental) aircraft, so 

there would be no "procedures" other than what I set myself.



I am a firm believer in standardization as I have done a great deal of 

computer software development, and I always follow the human interface 

standards unless there is a very good reason not to.



But there may rarely be reasons for overriding a standard, or you may have 

conflicting standards. For example, workflow patterns are typically set 

using a "left to right; top to bottom" flow model.



You will note that in most small single engine aircraft, the standard is 

to have the mag/starter switch on the left, with the master switch(es) 

(bat and alt) on the right. This violates the typical workflow model as 

you must first turn on the battery master (at minimum), then move left to 

start the aircraft.



I am considering overriding the "standard" placement and using a 

workflow-based placement.



In this instance, you would have the battery master on the left, with the 

mag/starter switch to the right.



The question then arises as to when the alt switch should be turned on, 

and I recall reading someplace at some time (how's that for precision!) 

that it might be best not to turn on the alt switch until after engine start.



If you would turn on the alt switch before engine start, I would use a 

layout of: battery master - alt - mag/starter.



But if you would turn the alt switch on after engine start, I would use a 

layout of: battery master - mag/starter - alt.



The concept would be maintaining the left-to-right workflow model...


	


     Very good sir. A lucid consideration of both human factors

     and the value of procedures but within the OBAM aviation venue.

     This validates my perceptions of your question and does not

     change my answer. Thank you for the clarification.



     Bob . . .

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