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Carb heat

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john_graham

Joined: 09 Aug 2007
Posts: 45
Location: Algonquin, IL

Posted: Sat Nov 17, 2007 8:08 am Post subject: Carb heat

No where have I read in any of the checklists when to

use carb heat or when it is recommended.  Obviously I

would turn it ON if my engine was running rough or

stopped as part of the emergency procedures.  But does

the M14 recommend the use of carb heat in the pattern?

 I can't find mention of it.

Thanks,



John P. Graham

CubFlyer1940(at)Yahoo.com

Cell phone  (847) 641-1330

Be a better sports nut!  Let your teams follow you 

with Yahoo Mobile. Try it now.  http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ

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_________________
John Graham
N15YK 1993 Yak-52
CubFlyer1940@Yahoo.com
(847) 641-1330

cjpilot710(at)aol.com
Guest

Posted: Sat Nov 17, 2007 9:19 am Post subject: Carb heat

The CJ-6 has a carburetor temp gage.  Watch it.

  

 The M-14 normally does not need carb heat in the pattern.  

  

 The old rule of thumb for icing is if the OAT is 10C or lower AND there is  visible moisture, (drizzle, fog, mist, etc), than there is a very good  chance icing conditions.  That is for airframe ice but take a look at you  carburetor temp gage.  If there is a marked arch on it, that is what you  should be watching.  The air temp as it passes though the carb drops  considerable as it passes though the throat.  Using the alternate air  simply takes warmer air from behind the engine and runs it into the carb.  In 1500 hours behind the HS6 and M14 I never had carb ice.  That does NOT  mean it will not happen since a number of folks have reported it here.  But  the airplane does have "alternate air".  Years ago when I put the M14 on my  CJ, I built a carb heat system.  I should have stuck with just alternate  air.  It is simpler and because the pressure carbs, don't  have icing  problems as standard carbs, it would have been just as  effective.  

  

 Jim "Pappy" Goolsby

  

  

  

  In a message dated 11/17/2007 11:10:54 A.M. Eastern Standard Time,  cubflyer1940(at)yahoo.com writes:

  	  Quote: 	
		  -->    Yak-List message posted by: John Graham    <cubflyer1940(at)yahoo.com>



No where have I read in any of the    checklists when to

use carb heat or when it is recommended.  Obviously    I

would turn it ON if my engine was running rough or

stopped as part of    the emergency procedures.  But does

the M14 recommend the use of carb    heat in the pattern?

I can't find mention of    it.

Thanks,



John P. Graham

CubFlyer1940(at)Yahoo.com

Cell    phone  (847) 641-1330

Be a better sports nut!  Let your    teams follow you 

with Yahoo Mobile. Try it now.     http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ



sp;             (And Get Some AWESOME FREE   find  you for                          -Matt Dralle,    List  es  y       -->                 - MATRONICS WEB FORUMS  ======================



	




  [quote][b]

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brian-1927(at)lloyd.com
Guest

Posted: Sat Nov 17, 2007 4:52 pm Post subject: Carb heat

On Nov 17, 2007, at 8:08 AM, John Graham wrote:



 	  Quote: 	
		   



 No where have I read in any of the checklists when to

 use carb heat or when it is recommended.  Obviously I

 would turn it ON if my engine was running rough or

 stopped as part of the emergency procedures.  But does

 the M14 recommend the use of carb heat in the pattern?

  I can't find mention of it.


	


There really isn't a need for carb-heat in our engines. In a standard  

carb the fuel is metered into the venturi which is upstream of the  

throttle valve. As the fuel evaporates it cools the air causing the  

moisture in the air to turn to ice. The ice usually forms on the  

throttle valve.



The pressure carb is really a single-point fuel injection system. The  

fuel spraybar is downstream of the throttle valve and there is  

nothing between the spraybar and the compressor impeller. There is no  

chance of ice ever forming on the compressor impeller.



So the only time you really need carb heat is if the inlet itself  

ices up (requiring alternate air) or if it is so cold that you need  

extra heat to get the fuel to vaporize when the engine is first started.



Are there any other times? Probably, but I can't think of any.



--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



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bpx2horn(at)aol.com
Guest

Posted: Sun Nov 18, 2007 6:57 am Post subject: Carb heat

I fly routinely in Northern Illinois and Southern Wisconsin in the extreme cold months of January and February. During these months in the event that a go-around is necessary, I and my teamates have found that applying carb heat on final helps to keep the engine from stuttering. I think Brian maybe right that after a low power setting the carb may cool a bit and the carb heat warms it enough to allow for better atomization of the fuel when dumping all that fuel in rapidly.

 

 Paul Hornick

 

 

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