carb ice

j bird

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Joined
Nov 11, 2005
Messages
1,828
Location
Cave Junction,OR.
Aircraft
Dominator/Airworthiness Certificate 9/06/12
Total Flight Time
26.5 duel,RAF,Sparrow-Hawk,Cavalon,Calidus.
I was reading engine outs, in general discussion,122 outs in5300 hrs. thats an average of 122 hours per out.

I would like to know if most of the gyro community, fly with carb heat installed on the engine? Would seem to me,carb ice would be common on engines without carb heat,in certain conditions.
j bird.
 
If you have a carby, I would have carby heat fitted as you could well need it !! Of course EFI engines do not get carby ice.
 
Most find it hard to belive,[ live'n in the desert n all] but i used to constantly get carb ice before i built a perminant heater for the 912.
It never bort me down, but was a pain in the ass when workn the power close to the ground.
 
birdy said:
Most find it hard to belive,[ live'n in the desert n all] but i used to constantly get carb ice before i built a perminant heater for the 912.
It never bort me down, but was a pain in the ass when workn the power close to the ground.

That's not hard to believe at all. Pure gasoline at the stoichiometric ratio can produce a drop of 40f when it evaporates. Add alcohol to the fuel, and that temperature drop can rise into the 50-60f range. Even on a 90f day, that could create enough drop to cause icing. If you're running rich (and there should always be a slight rich margin for safety - esp. on an AC 2-cycle) the drop is even greater.

And while the desert air is certainly warm, keep in mind that warm air can hold more water than cool air (thus relative humidities). Once the carb cools to the point of forming ice, you're at the mercy of the ambient moisture.
 
Lege, i was refer'n to the moisture content of air in deserts. No moisture, no ice.
Theres a bloke who regularly flys here for me and this is the only place he's experianced carb ice. His home is bout 100km further north of my lat and he's never had ice up there in over 1000 hours. First time he took off here[ after i warned him bout ice], he backed off the power at 100' and the motor went stone dead. He belived me bout the ice after that.

Scott, i had a webber on me old soob and the only time it used to ice was at idle while it was warming up.
 
birdy said:
Lege, i was refer'n to the moisture content of air in deserts. No moisture, no ice.

Do you own (or can you borrow) a sling cycrometer? It would be interesting to take RH readings on days when you do / do not experience icing. You know better than I that weather can be very weird.. all kinds of odd, localized phenomena.

Safe to say that the water is coming from *somewhere*.. if not in the air, perhaps your local fuel supply?
 
Do you own (or can you borrow) a sling cycrometer?
Probably.............. if i knew wot it was.:D

The moisture is cumn from the air allright, its just that most prople think theres no moisture in desert air.
[ theres no moisture in the ground, so i suppose its gota be in the air ay.]:rolleyes:
 
birdy said:
Do you own (or can you borrow) a sling cycrometer?
Probably.............. if i knew wot it was.:D

SImple, old-fashioned device for measuring relative humidity.. but they work quite well.

They incorporate a glass thermometer with an absorbent wick over the bulb. The wick is wetted with water, then the entire device is spun ('slung') around by hand on a pivoting handle. As the water evaportes, the temperature reading drops. Based on the drop, you can calculate the RH.
 
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