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Carburator Ice

Old 02-20-2007, 11:01 PM
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erogers
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Default Carburator Ice

Anybody ever have a carburator ice up on them?

First time we have had weather decent enough to fly in about a month. 40 degrees and no wind. So I decided to take advantage of the good weather and get some of the rust off. I flew my Katana Profile 46 with a Supertigre 45 on it and after I took off and was in the air for about 2 or 3 minutes I throttled back and discovered that I had no throttle control. at first I though maybe my throttle servo had failed, or the linkage had broke. After flying around till I ran out of fuel and landed I checked over everything and the throttle servo moved, but only a little, I couldn't see where anything else was binding. I was flying in my backyard, so I picked up all my stuff and headed for the house, after I took the plane downstairs in the basement I started to check things over a little closer and discover that the barrel of the carb would not move very much. In the process of trying to figure out why, it started to move more freely, until it finally moved freely the full length of travel just as it had prior to me taking off. After further inspection, I could not find anything that would have caused this. The only thing I can think of would be that because of the temperature, (a few degrees above freezing) and the humidity level in the air this combination with the air flowing into the carburator caused the carburator to ice up.

Thoughts anyone?

Eric
Old 02-20-2007, 11:52 PM
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DavidAgar
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Default RE: Carburator Ice

I have flown in alot colder weather than 40 degrees and never had any problem with ice. I suppose under the right conditions it could be possible, but I am leaning towards there being another problem. Good Luck, Dave
Old 02-21-2007, 12:11 AM
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Default RE: Carburator Ice

G'day Mate,
Some ST's have a bad habit of sticky throttle barrels, pull the throttle barrel out & make sure there are no, burrs or anything that will stop it rotating.
Old 02-21-2007, 10:45 AM
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Rodney
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Default RE: Carburator Ice

While highly unusual, I have had ice form on a four stroke intake pipe in weather much above freezing. This was just a coating of ice on the outside of the intake and did not interfere with the throttle action or engine performance. The latent heat of evaporation can be quite large with alcohol fuels or should I say latent cooling of evaporation? As the fuel is evaporated in the intake there is a lot of cooling.
Old 02-21-2007, 11:53 AM
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Default RE: Carburator Ice

Never had carb ice on a model engine.
Now I have had the engine get so cold that it would shut off because it could not get hot enough to keep the glow lit.
Unless is was snowing or the humidity was really high, I would not attribute your problem to carb ice.
Old 02-21-2007, 03:46 PM
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Default RE: Carburator Ice

The Humidity yesterday was 94% Yesterday afternoon, with a temperature of 38 degrees, and dew point of about 34 degrees. We had a heavy fog last night that still hasn't burned off yet today at noon. Not sure what or why exactly, but the problem seemed to be a symptomatic of ice forming inside the carb.

Eric
Old 02-21-2007, 05:33 PM
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Default RE: Carburator Ice

take the carb off the engine and put it in the freezer for an hour then see if the barrel can still rotate.if it does then it could have been ice if it doesnt then there is a clearance problem at low tempretures.
Old 02-21-2007, 10:05 PM
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Default RE: Carburator Ice

I've seen frost in the carb barrel a couple of times, but it didn't interfere with the carb operation.
Old 02-21-2007, 10:26 PM
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lparks
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Default RE: Carburator Ice

Humidity here is usually fairly low, but have often flown as low as 10 degrees without an issue. Fuel evaporation and air expanding after passing the venturi can easily cause icing in much higher ambient temperatures, but I cannot see that happening in a model engine at the throttle barrel. I think it more likely that the contracting carburetor body is binding on the throttle barrel at low temperatures...
Old 02-22-2007, 07:02 AM
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Roby
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Default RE: Carburator Ice

About 7 weeks ago I was flying in a light freezing rain.
The airframe was getting coated and a bit heavy but the
motor was not effected. Never skipped a beat.


Regards,
Roby

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