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Cessna Flaps motor

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bouguy

Joined: 23 Jan 2008
Posts: 8
Location: France

Posted: Sat Jan 03, 2009 8:41 am Post subject: Cessna Flaps motor

Hi ,



i am looking for the current draw of a 24v/28v flap motor

of a Cessna 172 and not able to find it .



thanks for help ,



Boullu guy .

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skywagon

Joined: 11 Feb 2006
Posts: 184

Posted: Sat Jan 03, 2009 9:09 am Post subject: Cessna Flaps motor

Probably best to use the flaps circuit breaker rating, amps, in case the 

flap mechanism gets stiff or worn and the elect. motor goes to max 

current...

D

---

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jan 03, 2009 10:28 am Post subject: Cessna Flaps motor

At 10:41 AM 1/3/2009, you wrote:

 	  Quote: 	
		  



Hi ,



i am looking for the current draw of a 24v/28v flap motor

of a Cessna 172 and not able to find it .



thanks for help ,



Boullu guy .


	


     How do you need to use the information? If for

     a load analysis, know that flaps are very low

     duty cycle (hence low energy) systems that are

     not big players in sizing an electrical system.



     If for circuit protection and wiring decisions,

     I think you'll find that this critter seldom

     draws more than 7 amps (extension during max

     allowable IAS for full flaps). You can check the

     size of a breaker in any of the 28v s.e. airplanes

     and go with that. It's probably a 10 or 15A breaker.

     You can wire with 14AWG and go with smaller breaker

     and upsize the breaker to and including 20A if

     you're getting nuisance trips. Assuming you're

     installing this motor/actuator in a OBAM aircraft,

     it could be that your flap geometry and air-loads

     are decidedly different that for the Cessna

     installation.



     Wire it with "too-big" wire and leave yourself

     room for resizing the breaker/fuse after you've

     had some time to acquire real-life experience

     with it.

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

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bouguy

Joined: 23 Jan 2008
Posts: 8
Location: France

Posted: Sun Jan 04, 2009 1:20 am Post subject: Re: Cessna Flaps motor

Hi Bob ,



thanks for your reply ;



it is not for a bus load analysis , as it is an intermittent load ;

seen a 10A breaker on a 24Volts Cessna 172 but as i am

building a faster aircraft with more flaps surfaces i thought it

was not correctly sized for me .

i am going to follow your indications : wiring with 14awg with

a 15 Amp breaker , and if it pops up , i will change for a 20 Amp.



i have a similar question for a Prestolite Power Pack rebuilt 

Aéroelectic 28volts  HYH-5001ECH ; what would be the correct 

wire  sizing and breaker ? 



thanks again for help ,

Boullu guy .

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jan 04, 2009 8:21 am Post subject: Cessna Flaps motor

At 03:20 AM 1/4/2009, you wrote:

 	  Quote: 	
		  



Hi Bob ,



thanks for your reply ;



it is not for a bus load analysis , as it is an intermittent load ;

seen a 10A breaker on a 24Volts Cessna 172 but as i am

building a faster aircraft with more flaps surfaces i thought it

was not correctly sized for me .


	


    "faster", "more" etc. are poor quantifiers of design.

    The air-loads on a flap system are directly related to

    area and IAS . . . but FORCE on the actuator is also

    a function of rates and mechanism.



 	  Quote: 	
		  i am going to follow your indications : wiring with 14awg with

a 15 Amp breaker , and if it pops up , i will change for a 20 Amp.



i have a similar question for a Prestolite Power Pack rebuilt

Aéroelectic 28volts  HYH-5001ECH ; what would be the correct

wire  sizing and breaker ?


	


    It's a WAG. Without specific engineering data for

    using this component in the proposed system, the

    conservative approach is duplicate what was in the

    original system and then take measurements during

    your fly-off to deduce whether or not modifications

    are called for. It's not likely that you're going

    to experience any big surprises. Even if you do,

    the worst thing that happens is an adjustment of

    wire size and protection.



    I get a lot of emails on this and similar topics.

    Many folks think that from first flight on a new

    airplane until s/n 100 rolls of the assembly line,

    few if any changes happen to the design. Our

    OBAM aircraft are no different with respect to

    verifying achievement of design goals . . .

    The potential for risk in sizing wire and fuses

    is very low. WAG it, verify it, then modify as

    necessary.

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

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