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'Tis the Season' Reminder

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Dennis Thate

Joined: 18 Nov 2010
Posts: 362

Posted: Wed Oct 24, 2012 2:37 pm Post subject: 'Tis the Season' Reminder

The temperature-dew point spread tells a pilot how close the air is to being 100% saturated, Fortunately old wise men 503 Rotax  pilots rarely fly in such conditions.

There seems to be a general consensus that two strokes gas /oil mixtures are invincible to icing, if you have the BING 54 carbs on your two stroke 503 as most Kolb Firestar pilots have they are not as prone to carb icing, because it works with a piston and not a valve as most other carbs do so most ice that will be formed will by design be sucked into the engine, and heated up to melt down preventing the carb piston itself from freezing in a fixed position.

The highest probability for carb icing is during a long decent. It's good General Aviation airmanship to add carb heat and clear the throttle at intervals during a glide approach, keep the power up, and remain with gliding distance of good fields until you get home and don't reduce power until you are sure you can make the field.

Fly Safe, stay revved up  !



http://www.800-airwolf.com/pdffiles/ARTICLES/part44.pdf

_________________
Both optimists and pessimists contribute to our society. The optimist invents the airplane and the pessimist the parachute. ~Gil Stern

Last edited by Dennis Thate on Thu Oct 25, 2012 9:28 am; edited 1 time in total

phactor9

Joined: 16 Jun 2011
Posts: 78

Posted: Wed Oct 24, 2012 3:28 pm Post subject: 'Tis the Season' Reminder

I wonder what risks a diaphragm carb suffers with carb ice? ( I.e. a Tillotson ) At least there's no slide to stick. Perhaps just reduced air intake, resulting in higher oil-to-fuel ratio?



Assuming the whole throat doesn't fill up with ice, does that mean fouled plugs are the biggest problem?



Phil H

FF11-4-76



--- On Wed, 10/24/12, Dennis Thate <retroman(at)frontier.com> wrote:

 	  Quote: 	
		  

From: Dennis Thate <retroman(at)frontier.com>

Subject: 'Tis the Season' Reminder

To: kolb-list(at)matronics.com

Date: Wednesday, October 24, 2012, 6:37 PM



--> Kolb-List message posted by: "Dennis Thate" <[url=/mc/compose?to=retroman(at)frontier.com]retroman(at)frontier.com[/url]>



The temperature-dew point spread tells a pilot how close the air is to being 100% saturated, Fortunately old wise men 503 Rotax  pilots rarely fly in such conditions.

There seems to be a general consensus that two strokes gas /oil mixtures are invincible to icing, if you have the BING 54 carbs on your two stroke 503 as most Kolb Firestar pilots have they are not as prone to carb icing, because it works with a piston and not a valve as most other carbs do so most ice that will be formed will by design be sucked into the engine, and heated up to melt down preventing the carb piston itself from freezing in a fixed position.

The highest probability for carb icing is during a long decent. It's good General Aviation airmanship to add carb heat and clear the throttle at intervals during a glide approach, keep the power up, and remain with gliding distance of good fields  until you get home and don't reduce power until you are sure you can make the field.

Fly Safe, stay revved up  !



--------

Both optimists and pessimists contribute to our society.  The optimist invents the airplane and the pessimist the parachute.  ~Gil Stern





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 [quote][b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Oct 24, 2012 3:44 pm Post subject: 'Tis the Season' Reminder

At 06:37 PM 10/24/2012, Dennis Thate wrote:

  	  Quote: 	
		  --> Kolb-List message posted by: "Dennis Thate" <retroman(at)frontier.com>



 There seems to be a general consensus that two strokes gas /oil mixtures are invincible to icing, if you have the BING 54 carbs on your two stroke 503 as most Kolb Firestar pilots have they are not as prone to carb icing... 	


 .. but it still can happen.  I have had two engine failures that I can only attribute to icing... no other apparent cause, very close temperature and dewpoint.  In my case it's a Mikuni, but that's very similar to a Bing.  I was lucky, in both cases I was able to restart, but I was sure picking landing fields!



 -Dana



 

 

 --

 The most exciting phrase to hear in science, the one that 

 heralds new discoveries, is not Eureka! (I found it!) but rather, 

 'hmm.... that's funny...'

 --Isaac Asimov

    [quote][b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Oct 24, 2012 3:44 pm Post subject: 'Tis the Season' Reminder

At 07:28 PM 10/24/2012, Phil wrote:

  	  Quote: 	
		  I wonder what risks a diaphragm carb suffers with carb ice? ( I.e. a Tillotson ) At least there's no slide to stick. Perhaps just reduced air intake, resulting in higher oil-to-fuel ratio? 	


 In a traditional carb, ice tends to build up on the butterfly, so I assume it would be the same with a Tillotson or Walbro.  The oil in the mix and slight puffback of a 2-stroke I think is the main thing that helps us, not the fact that the Bings are slide carbs.



 -Dana

 --

 The most exciting phrase to hear in science, the one that 

 heralds new discoveries, is not Eureka! (I found it!) but rather, 

 'hmm.... that's funny...'

 --Isaac Asimov

    [quote][b]

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Thu Oct 25, 2012 4:25 am Post subject: Re: 'Tis the Season' Reminder

Years ago my brother in law was flying his Quicksolver MX, had a Cuyuna with a Mikuni on it, and it was a fall day, humid and damp. It was acting up, so we pulled off the aircleaner, tied it down, and let it run for awhile. 



After a while, we got to watch a little "half-volcano" of ice crystals build up around the front side of the slide needle as the fuel was coming up around the needle. It never got big enough to close the throat, but it did get big enough to alter the proper airflow function of the carb. If I remember right, it was about 3/8" high, and 1/4" wide at the base.

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

zeprep251(at)aol.com
Guest

Posted: Thu Oct 25, 2012 3:44 pm Post subject: 'Tis the Season' Reminder

It seems that carbs that have cross structure down stream of the fuel discharge point ice more readily.The Bing 64 on the Jabiru is the worst I've experienced.Have any of the 912 engines had this issue?

 G.Aman MK3 C Jabiru 2200A 765 hrs electric carb heat    

  

     

  

     

  

    --

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Fri Oct 26, 2012 4:19 am Post subject: Re: 'Tis the Season' Reminder

Gary,

Unless your Jab2200 is a very very early one, the Bing carb on it is a 94 (40mm). They used a 64 model (36mm) for only a short while and it didn't take them very long to determine it was not big enough. However, they are of similar design and function much the same way,



I've not had any carb icing in my Slingshot with Jab2200 but in the 11 years I've been flying Rotax 912 engines, I've had two carb ice incidents. Detecting it early both times, I was able to get rid of it by cycling the throttle idle to WOT, back and forth a couple times. In both cases it was in warm weather with high humidity.

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_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

byoungplumbing(at)gmail.c
Guest

Posted: Fri Oct 26, 2012 6:48 am Post subject: 'Tis the Season' Reminder

I had a similar episode  last spring...   about 60 65 deg f  humidity was up 

,high but not extremely high,      I had been out about an hour and was 

coming back into the pattern when I pulled the throttle back, I heard some 

funny/different noises,,,  cycled the throttle a couple of times, a bit more 

noise,  and landed promptly.   when I shut the engine down I hurried out and 

could see a very thin film of ice on the outside of the carb.

I have a friend that moved here from florida,,, and he said on a humid day 

after a rain, carb ice was routine on his 912.   he had to  add a carb 

heater or limit his flying days. he was flying a plane in tractor 

configuration.



boyd young

mkiii 912 utah



 	  Quote: 	
		  >>>>>>>>>>>>>>>>>>>

Gary,
	


I've not had any carb icing in my Slingshot with Jab2200 but in the 11 years 

I've been flying Rotax 912 engines, I've had two carb ice incidents. 

Detecting it early both times, I was able to get rid of it by cycling the 

throttle idle to WOT, back and forth a couple times. In both cases it was in 

warm weather with high humidity.



--------

Thom Riddle

Buffalo, NY (9G0)

gcvisel

Joined: 23 Oct 2012
Posts: 11
Location: United States

Posted: Fri Oct 26, 2012 9:42 am Post subject: 'Tis the Season' Reminder

   Is there a carb heat mod for the 503? --Gerry



 On Fri, Oct 26, 2012 at 9:48 AM, b young <byoungplumbing(at)gmail.com (byoungplumbing(at)gmail.com)> wrote:

 [quote]--> Kolb-List message posted by: "b young" <byoungplumbing(at)gmail.com (byoungplumbing(at)gmail.com)>

 

I had a similar episode  last spring...   about 60 65 deg f  humidity was up ,high but not extremely high,      I had been out about an hour and was coming back into the pattern when I pulled the throttle back, I heard some funny/different noises,,,  cycled the throttle a couple of times, a bit more noise,  and landed promptly.   when I shut the engine down I hurried out and could see a very thin film of ice on the outside of the carb.

 I have a friend that moved here from florida,,, and he said on a humid day after a rain, carb ice was routine on his 912.   he had to  add a carb heater or limit his flying days. he was flying a plane in tractor configuration.

 

boyd young

mkiii 912 utah[b]

zeprep251(at)aol.com
Guest

Posted: Fri Oct 26, 2012 11:44 am Post subject: 'Tis the Season' Reminder

It must be a 94.Don't see any identification on the casting,just looked like a 64.

   G.Aman

  

     

  

     

  

    --

zeprep251(at)aol.com
Guest

Posted: Fri Oct 26, 2012 12:03 pm Post subject: 'Tis the Season' Reminder

The ice will build at cruise power settings,and the power loss is so gradual that you may not catch it.But you WILL notice when the ice breaks loose and the engine gags on it for a couple of revolutions.It gets me at warm up speeds,1100rpm,and will almost die without heat.If you go to idle it will quit.It must ice over those small ports just aft of the throttle plate as well.You've seen some pictures of the fog we get up here,great flying above the broken stuff but icing down low.    G.A.

    

         

    

         

    

        --

jbhart(at)onlyinternet.ne
Guest

Posted: Sat Oct 27, 2012 3:23 pm Post subject: 'Tis the Season' Reminder

Date: Wed, 24 Oct 2012 16:28:26 -0700 (PDT)

From: Phil <phactor9(at)yahoo.com>

 	  Quote: 	

I wonder what risks a diaphragm carb suffers with carb ice? ( I.e. a 

Tillotson ) At least there's no slide to stick. Perhaps just reduced air 

intake, resulting in higher oil-to-fuel ratio?

 	  Quote: 	

Assuming the whole throat doesn't fill up with ice, does that mean fouled 

plugs are the biggest problem?

 	  Quote: 	

Phil,

 	  Quote: 	
		  From the few flights I have with the MZ 34 with a Tillitson carburetor, I 

found that it will ice up.  Always I make a high approach so that if the 

engine quits I can always make the field.  This means that one must close 

the throttle and spill altitude and results in a cold engine when one 

reaches the point of round out and flare.  After roll out the engine starts 

easily.

Since I use mixed fuel, there is no reason to expect fouled plugs.

To get around this icing up problem, I searched the web and found some small 

bolt heater that is  used on KTM motorcycle engine carburetors.  I drilled 

the Tillotson carburetor and mounted one.  I have not had a chance, as yet, 

to check it out but you can see how it was done at the bottom of:

http://jackbhart.com/firefly/firefly153.html

Jack B. Hart FF004

Winchester, IN

nationcap(at)comcast.net
Guest

Posted: Sat Oct 27, 2012 7:37 pm Post subject: 'Tis the Season' Reminder

When I was flying 172s, the SOP was to turn on carb heat when entering the pattern and  pulling the throttle back as there was a greater tendency for carb icing.



Sent from my iPad



Brad



On Oct 26, 2012, at 8:48, "b young" <byoungplumbing(at)gmail.com> wrote:



 	  Quote: 	
		   

 

 I had a similar episode  last spring...   about 60 65 deg f  humidity was up ,high but not extremely high,      I had been out about an hour and was coming back into the pattern when I pulled the throttle back, I heard some funny/different noises,,,  cycled the throttle a couple of times, a bit more noise,  and landed promptly.   when I shut the engine down I hurried out and could see a very thin film of ice on the outside of the carb.

 I have a friend that moved here from florida,,, and he said on a humid day after a rain, carb ice was routine on his 912.   he had to  add a carb heater or limit his flying days. he was flying a plane in tractor configuration.

 

 boyd young

 mkiii 912 utah

 

 Gary,

 I've not had any carb icing in my Slingshot with Jab2200 but in the 11 years I've been flying Rotax 912 engines, I've had two carb ice incidents. Detecting it early both times, I was able to get rid of it by cycling the throttle idle to WOT, back and forth a couple times. In both cases it was in warm weather with high humidity.

 

 --------

 Thom Riddle

 Buffalo, NY (9G0)

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