Holy crap, I lost my engine last night...

[urflyingme?!]

On another side note, I'd be interested to see how applying more power may even increase the carb icing factor due to the greater amount of airflow; and possible greater cooling factor?

This of course is backed up by no way in science, just a curiosity...

 

[dkelly]

My question:
Then why's it there??!

Carb heat can also be used for an alternate means of airflow to enter the engine in heavy rain conditions or icing, where as the air filter is restricted/blocked.

 

[urflyingme?!]

Carb heat can also be used for an alternate means of airflow to enter the engine in heavy rain conditions or icing, where as the air filter is restricted/blocked.

:erm:

I think that you may be refering to alternate air....

But then again read my last post! HA

 

[barnyard]

nice job keeping it in tight. I've seen too many guys teach rediculous patterns in singles; you know the full flaps on the vasi/2000 RPM approach on 3 mile final approach. But thats how the airlines do it so it must be right.

 

[avbug]

Carburetor heat may also be used as an alternate air source, so long as the blockage isn't in the carburetor itself, or downstream from the carburetor.

Carburetor icing's greatest potential is at high power settings, when the temperature and pressure drop in the carburetor is greatest. Icing is also possible at idle throttle closed position, when ice affects the idle jet. Going from an iced condition, in icing conditions, to a full throttle setting can cause a rapid development of ice and total power loss.

The mentality that carburetor ice is less likely on engines which attach the carburetor to the sump is flawed. Carburetor ice isn't forming as a result of conductive heating or lack thereof via the carburetor body; it's forming in the airstream, and adjustment of the carburetor airstream temperature is what creates or prevents it.

On most all radial engines, the carburetor is mounted atop and behind the engine, where heating is greatest, and most radial engines will ice like a SOB in the right conditions. "Full" or "No" carb heat isn't the issue; setting the proper carb air temperature is. If any carb position is unlikely to ice based on location, a downdraft carb on top of a hot engine supercharger is the one...but they ice like nobodies business.

Forget about lycoming this and continental that. If it has a carburetor, it's susceptible to carb icing, period.

And it will fail. As you now know.

The idea that carb heat should be all or nothing is flawed, and applies a very un-airman like and very unprofessional sense of guesswork to what really is science; carb air temperature. Lacking a gauge, your best guess is full heat or none, but it's still a wild, rough guess.

Properly applied, partial heat is appropriate, in order to put the carb air temp in it's proper place.

 

[urflyingme?!]

i KNEW it

I guess I learned something in school

 

[aucfi]

The bottom of the green arc is lower in the Piper than in the Cessna, but isn't it the same engine?

I know the green arcs on tachometers represent normal operating speeds for the engine/prop on a constant speed setup. If your operating (engine making power) in the green arc, the engine is working to turn the prop. If you are out of the green arc, the relative wind is turning the prop, not the engine. I used to think the green arc was the "safe zone" as far as no carb ice but my mechanic showed me otherwise. Ever seen a yellow arc on a tach? Thats what made me question it.

My question is, does the same apply for fixed pitch setups? The green arc on my cub covers the entire dial up to the redline and I can assure you that it is not immune to carb ice.

 

[mtrv]

The mentality that carburetor ice is less likely on engines which attach the carburetor to the sump is flawed. Carburetor ice isn't forming as a result of conductive heating or lack thereof via the carburetor body; it's forming in the airstream, and adjustment of the carburetor airstream temperature is what creates or prevents it.

Forget about lycoming this and continental that. If it has a carburetor, it's susceptible to carb icing, period.

You might make a good preacher for a bunch of sheep, but I'd suggest that anyone who is really interested in this subject, to do research across the internet, including forums, Lycoming, Piper, etc.

There are many ideas, reasoning, explanations and answers. Some agree with Avbug, and many don't. To except Avbug's gospel as the total last word, is in effect---flawed. This is, and has been a highly debated suject. You can read and read, and read, and still not get a positive for sure, no mistake about it answer.

Regarding carb heat as a habit; without, having to re-write a quote from a Piper's POH, I'll just paste a copy thats already posted.

GROUND CHECK
...
Carburetor heat should also be checked prior to take-off to be sure that the control is operating properlyand to clear any ice which may have formed during taxiing. Avoid prolonged ground operation with carburetor heat ON as the air is unfiltered.
...

CRUISING
...
The continuous use of carburetor heat during cruising flight decreases engine efficiency. Unless icing in the carburetor are severe, do not cruise with the heat on. Apply full carburetor heat slowlyand only for a few seconds at intervals determined by icing severity.
...

APPROACH AND LANDING
...
Carburetor heat should not be applied unless there is an indication of carburetor icing, since the use of carburetor heat causes a reduction in power which may be crifical in case of a go-around. Full throttle operation with heat on is likely to cause detonation.

The idea that carb heat should be all or nothing is flawed, and applies a very un-airman like and very unprofessional sense of guesswork to what really is science; carb air temperature. Lacking a gauge, your best guess is full heat or none, but it's still a wild, rough guess.

Properly applied, partial heat is appropriate, in order to put the carb air temp in it's proper place.

That's correct. If you have a gauge, then fine. But without, it's all or nothing. At least that's what the majority seems to believe.

 

[Amish RakeFight]

You can keep the carb heat on continuously during cruise. Just lean it out.

 

[Dr Pokenhiemer]

You are correct RakeFight--same goes for higher altitude takeoffs to a certain extent. Apply carb heat, the lean the mixture to get the rise in RPM.