What is the purpose of the Carb heat

WannFly said:
Donno
Click to expand...
Do you believe addition of heat from any source would help?
Do you think there will be any differences between a carb mounted on a hot oil sump and a remote mounted carb. (like the 0-200 and 0-470)
 
Tom-D said:
Do you believe addition of heat from any source would help?
Do you think there will be any differences between a carb mounted on a hot oil sump and a remote mounted carb. (like the 0-200 and 0-470)
Click to expand...
Yah logically it would definitely help. I just don't if my carb is mounted on the oil sump or not

Sent from my SM-G935V using Tapatalk
 
WannFly said:
Yah logically it would definitely help. I just don't if my carb is mounted on the oil sump or not

Sent from my SM-G935V using Tapatalk
Click to expand...
Got 0-320 ? It is.
 
there are two methods of attaching a carb to the engine, remotely like the 0-200 and the 0-470 where they do not attach the carb to the oil sump. these engines have intake spider where the carb is attached and intake tubes that run from there to each cylinder.

Lycoming nearly always have the carb attached directly to the oil sump. these are not as prone to icing as the remote mounted carbs
Cessna 150 / 182 are well known for there ability to make carb ice.
The pipers not so much.
 
Half Fast said:
The Tecnams I fly don't have carb heat. Is there something that makes Rotax engines less prone to carb ice? I suspect the air intake location causes the engine to breathe warm air all the time.
Click to expand...
My ride (Merlin GT, Rotax 912) picks up carb air from behind the engine - so it is warmed up a bit by the cylinders / radiator/ etc. Moves you to the right on the icing chart.

My 912 has a Bing constant vacuum [constant velocity or constant depression if you prefer] carb, not a pressure carb. It would tend to open the slide if there were some ice build up, but I don't know that i would call it immune.
 
Capt. Geoffrey Thorpe said:
My ride (Merlin GT, Rotax 912) picks up carb air from behind the engine - so it is warmed up a bit by the cylinders / radiator/ etc. Moves you to the right on the icing chart.

My 912 has a Bing constant vacuum [constant velocity or constant depression if you prefer] carb, not a pressure carb. It would tend to open the slide if there were some ice build up, but I don't know that i would call it immune.
Click to expand...

my Warner attached the carb to the bottom of the plenum chamber, it never iced.
 
Clark1961 said:
Carb heat is avoided during warm up and taxi because the intake air is not filtered. Check card heat as part of the run-up. Ice should be cleared at that point.
Click to expand...
I was just reviewing the Carb Heat mentions in our 182P model's POH. Ironically, they specifically mention using Carb Heat right after startup and while warming the engine for cold weather operations. Another non-typical recommendation for carb heat is when flying through heavy rain. And there is a mention of recommending using it if flying through icing conditions when the air filter being iced up is suspected. Finally, they do recommend partial carb heat usage in a few different places. Of course the manual was written like 45yrs ago so maybe some of these recommendations are no longer ideal.
 
Sinistar said:
I was just reviewing the Carb Heat mentions in our 182P model's POH. Ironically, they specifically mention using Carb Heat right after startup and while warming the engine for cold weather operations. Another non-typical recommendation for carb heat is when flying through heavy rain. And there is a mention of recommending using it if flying through icing conditions when the air filter being iced up is suspected. Finally, they do recommend partial carb heat usage in a few different places. Of course the manual was written like 45yrs ago so maybe some of these recommendations are no longer ideal.
Click to expand...
Reading the FM. Excellent. Carb heat on the ground can be a tough call. Carb heat in flight is usually no biggie. Some Mooney’s have a filter bypass for use in cruise flight in an attempt to get a little more efficiency from the intake system.

Icing conditions can ruin your day several ways. Fuel injected engines typically have “alt air” so the engine has another way to get intake air. On some engines the alt air is a “suck-in” door and other engines have a manual control. For turbocharged engines some folks say to leave alt air open until shutdown if it has been opened because of iced intake. The idea is to avoid sucking ice into the turbo.
 
Tom-D said:
on your PA-28 isn't the carb bolted directly to the hot oil sump? does that make a difference ?
Click to expand...

It does, if the oil's hot. First startup of the day it's cold, and carb ice can get you. Many times I've seen Lycomings ice up shortly after startup on beautiful sunny summer mornings, and sometimes during the runup. When that oil is at ambient temperature the Lycoming is no more ice-resistant than any other carbureted angine.
 
Tom-D said:
Did we just change the subject?
Click to expand...

Nope. Still talking about carb heat and carb ice and carburetors. The Rotax, someone said, has a pressure carb that is ice-resistant.

Figure2-28.jpg


In this carb, the only venturi is at the inlet and it is used to gauge air velocity and indirectly figure the weight of air entering it. The impact air and venturi suction control the fuel flow. The fuel is sprayed into the air after the throttle plate, so icing of the plate is impossible.

Still, the evaporation in the manifold could cause some ice as could that inlet venturi. The induction system would be designed to provide some heated air or a heated manifold to minimize it.
 
They call it ice resistant because the ice will form at or after the point of fuel injection, this does not change the pressures produced at the Venturi, fuel flow will remain until the intake is clogged with ice, after this happens the airflow thru the Venturi will change, thus the fuel flow change
 
One could argue that the types that are “resistant” to icing also create complacency. Engine power loss checklists in most of these types include carb heat, but folks who never use it will tend not to use it during a power loss, either.

Folks who have stuff that ices up more, have that flow in their heads and hands that includes the carb heat lever before fiddling, best glide, pick a spot, pop the doors, and land. :)
 
denverpilot said:
One could argue that the types that are “resistant” to icing also create complacency. Engine power loss checklists in most of these types include carb heat, but folks who never use it will tend not to use it during a power loss, either.

Folks who have stuff that ices up more, have that flow in their heads and hands that includes the carb heat lever before fiddling, best glide, pick a spot, pop the doors, and land. :)
Click to expand...
YEP ! agree whole heartedly, you don't do what is called for in the check lists you get what you deserve.
don't have a lot of sympathy for the dumb ones :)
 
Just asking, Is there any certified aircraft engine with electronic ignition and multi port fuel injection? I know that SDS has an after market for Exp.
 
Tom-D said:
there are two methods of attaching a carb to the engine, remotely like the 0-200 and the 0-470 where they do not attach the carb to the oil sump. these engines have intake spider where the carb is attached and intake tubes that run from there to each cylinder.

Lycoming nearly always have the carb attached directly to the oil sump. these are not as prone to icing as the remote mounted carbs
Cessna 150 / 182 are well known for there ability to make carb ice.
The pipers not so much.
Click to expand...
Lycoming powered Supercubs are famous for making ice. So much for the warm sump theory.

Warming the intake air robs power, thus the popularity of cold air sumps on exp FI
Lycoming variants.
 
Last edited:
I know of a simple blown breaker shutting down an EFI and causing an airplane to crash. Once reset on the ground the system worked perfectly. EFI may be the next big thing but mechanical injection works great, too, and has no dependence on electricity to make it go.
 
Clark1961 said:
Some Mooney’s have a filter bypass for use in cruise flight in an attempt to get a little more efficiency from the intake system.
Click to expand...

F and earlier models had a pretty restrictive intake system, opening the "Ram Air" to bypass the air filter and ducting would add 2-3" of MP at cruise. For the J, Mooney re-designed the intake system, and opening Ram air adds less than 1" of MP. We don't use it, and I know of few J operators that do.
 
Sinistar said:
I like the Avatar....that's why I kept posting more carb heat posts. Allison is really a man :(
Click to expand...
It’s the interwebz. All women are men and all underage girls are FBI agents. And maybe I’m really a dog.
 
I am very much a woman. Now, back to to topic at hand. How were newer planes designed to not need carb heat? What changed.
 
You must log in or register to reply here.
Back
Top