After warching multiple private pilot videos on youtube, I now have a clear understanding as to what a carb heat is, and why it is applied. Thanks for a very simple and informative video.
Yes! Carb Heat is only taught as a procedural item for your checklist, and so that's the only way I've learned it. I've always wanted to understand it, and to know why you need it at different times, regardless of ambient temperature. This is the complete explanation I was hoping to find. Thanks!
Very useful. There was just one part that I didn't feel was fully explained. At 2:00 you talk about low RPM means the butterfly valve is nearly closed. That's clear enough. But then you say that means the temperature drop "is significant because the Venturi effect is significant." I didn't really feel that was a proper explanation and I'm not really sure what point was being made here. Any clarifications very welcome (by anyone)! Is it saying that ice formation causes the butterfly valve to become rigid and thereby cannot move, so the Venturi effect can't pull in the fuel mixture to be supplied to the engine? Or something else?
Good question. When the butterfly valve is nearly closed, the fuel/air mixture has much less space to squeeze through. This causes the static pressure to further decrease and consequently the temperature to significantly decrease.
@@flightclubonline Aha, so it exacerbates the problem with static pressure cooling at lower engine RPM. Thanks for the quick response! Directly cleared up my confusion! :) What a great channel this is. I'm very glad I found it.
Yeah, I am quite sure use of the term static pressure is incorrect here, although aviators use it more frequently due to analogy to the aircraft’s static pressure system. Let me try to clarify it somewhat and check what I remember from university lectures. Sorry for my language, I am not a native speaker of English. According to Bernoulli’s equation, the fluid’s momentary pressure consists of three elements: its hydrostatic pressure (elevation of the fluid x density x gravitational acceleration = potential element of pressure) and the flow derived element (1/2 x density x linear velocity squared = kinetic element of pressure) and the pressure along the line of flow; if you add these all up you get a constant. What it means is that when you have an airflow in a tube with uniform diameter and there is a section with smaller effective diameter, given the mass flow is constant in a tube, your linear velocity of the fluid increases and it also means a pressure drop at the very same point where the velocity increase happens. Okay, now we have a pressure drop and when this happens, the volume of the compressible fluid (air-gas mixture) increases and this state change is also close to adiabatic because there is not enough time to exchange energy with the environment, therefore this fluid will cool down. It would act exactly like this if it was an ideal gas (ref. ideal gas law), but since we added gasoline into the equation, we have an evaporative cooling effect of that (because gasoline would like to keep its vapor pressure), too, which adds substantially to the temperature drop.
For the longest time I could never understand why the ice formed. Everybody just said "icing" which made me wonder how the heck does such a massive pressure differential freeze water vapor? Then I read somewhere "fuel evaporation icing" and I had a eureka moment. The evaporation rate and cooling effect of Avgas mixed with the water vapor..
how is there venturi effect more significant when the throttle is closed? wouldn't the more open the throttle, the more air is allowed to flow through the venturi causing the venturi effect to be more significant?
Vacuum drops as throttle opens, and it's because as the throttle opens, it's reducing the restriction. Vacuum is effectively is a measure of restriction. Venturi relies on vacuum... More vacuum = more pull on Venturi. Modern engines use MAP reading (Manifold Absolute Pressure) as a way to read engine load (high vac aka minus pressure, is light load. Low vac aka almost positive pressure, is heavy load). Vacuum will read around -18" mercury at idle, because a lot of air is being pulled through a tiny "straw". Venturi works on pressure drop principle, so the more pressure drop it gets, the more fluid it can pass through. At WOT (Wide Open Throttle) the "straw" is now equivalent to a Pringle's tube, so all the air passes through with minimum restriction, as a result the vacuum drops to almost 0". The Venturi still provides enough fuel because the lack of pressure is compensated for by a higher volume of air passing by it.
There are many advantages to Fuel Injection, such as increased efficiency but carburettors are cheaper to manufacture, make hot engine starts easier and are less prone to issues with fuel contamination.
Please be 100 percent accurate, if you are going to teach. The carburetor will not be in the line of sight of a pilot, if on top! That's a lie. 2nd, the reason the carburetor is not on top of the engine is incase there is a fuel leak and that fuel could spill all over a hot engine igniting it, and turning it into a fireball.
After warching multiple private pilot videos on youtube, I now have a clear understanding as to what a carb heat is, and why it is applied. Thanks for a very simple and informative video.
Glad to help! Thank you so much for letting us know.
Yes! Carb Heat is only taught as a procedural item for your checklist, and so that's the only way I've learned it. I've always wanted to understand it, and to know why you need it at different times, regardless of ambient temperature. This is the complete explanation I was hoping to find. Thanks!
Thank you! Glad the video was helpful.
Thank you for providing such clarity with your superb illustrations.
I’m on day 2 of rpl and this was super helpful even though we already went over this, thank you!
Glad it was helpful!
Best video for Private Pilots to explain the carby. Thanks!
Glad it was helpful!
Incredibly simple!! Thank you!!
Thanks for your kindly explanation , after watching your video, I have understood much better about the carburetor.
thank you a lot for this easy understanding video !
Simple and clearly this channel
Very educational.
Thanks for the video
this is so elegantly explained ! thanks a lot for the great video
Glad it helped!
This was what I was really looking for!! Thankss!!!!!
Absolutely phenomenal video clearly explain the intricacies of carb heat. Thank you
Glad it was helpful!
There is a special place in heaven for you, @flight-club! Thanks!
Thank you!
Thanks again. Keep it up!
Thank you for the positive feedback.
New one! ^^ i like it
Great videos, please make more
Perfect!!!
amazing ! thank Youu
Welcome!
very helpful
Thank you.
Please create more videos. And get more visual tutorials on the site and on the Instagram page.🤩
Our pilots really need your art🤓
THX !
Welcome!
Nice!
Thanks!
Very useful. There was just one part that I didn't feel was fully explained. At 2:00 you talk about low RPM means the butterfly valve is nearly closed. That's clear enough. But then you say that means the temperature drop "is significant because the Venturi effect is significant." I didn't really feel that was a proper explanation and I'm not really sure what point was being made here. Any clarifications very welcome (by anyone)!
Is it saying that ice formation causes the butterfly valve to become rigid and thereby cannot move, so the Venturi effect can't pull in the fuel mixture to be supplied to the engine? Or something else?
Good question. When the butterfly valve is nearly closed, the fuel/air mixture has much less space to squeeze through. This causes the static pressure to further decrease and consequently the temperature to significantly decrease.
@@flightclubonline Aha, so it exacerbates the problem with static pressure cooling at lower engine RPM. Thanks for the quick response! Directly cleared up my confusion! :) What a great channel this is. I'm very glad I found it.
Thank you!
Yeah, I am quite sure use of the term static pressure is incorrect here, although aviators use it more frequently due to analogy to the aircraft’s static pressure system. Let me try to clarify it somewhat and check what I remember from university lectures. Sorry for my language, I am not a native speaker of English. According to Bernoulli’s equation, the fluid’s momentary pressure consists of three elements: its hydrostatic pressure (elevation of the fluid x density x gravitational acceleration = potential element of pressure) and the flow derived element (1/2 x density x linear velocity squared = kinetic element of pressure) and the pressure along the line of flow; if you add these all up you get a constant. What it means is that when you have an airflow in a tube with uniform diameter and there is a section with smaller effective diameter, given the mass flow is constant in a tube, your linear velocity of the fluid increases and it also means a pressure drop at the very same point where the velocity increase happens. Okay, now we have a pressure drop and when this happens, the volume of the compressible fluid (air-gas mixture) increases and this state change is also close to adiabatic because there is not enough time to exchange energy with the environment, therefore this fluid will cool down. It would act exactly like this if it was an ideal gas (ref. ideal gas law), but since we added gasoline into the equation, we have an evaporative cooling effect of that (because gasoline would like to keep its vapor pressure), too, which adds substantially to the temperature drop.
Very well explained for a non native speaker of English :) Thank you so much for your contribution!
For the longest time I could never understand why the ice formed. Everybody just said "icing" which made me wonder how the heck does such a massive pressure differential freeze water vapor? Then I read somewhere "fuel evaporation icing" and I had a eureka moment. The evaporation rate and cooling effect of Avgas mixed with the water vapor..
why not just install another air filter on the second pipe so that the air is filtered even when we use the carb heat??
how is there venturi effect more significant when the throttle is closed? wouldn't the more open the throttle, the more air is allowed to flow through the venturi causing the venturi effect to be more significant?
Vacuum drops as throttle opens, and it's because as the throttle opens, it's reducing the restriction. Vacuum is effectively is a measure of restriction. Venturi relies on vacuum... More vacuum = more pull on Venturi. Modern engines use MAP reading (Manifold Absolute Pressure) as a way to read engine load (high vac aka minus pressure, is light load. Low vac aka almost positive pressure, is heavy load).
Vacuum will read around -18" mercury at idle, because a lot of air is being pulled through a tiny "straw". Venturi works on pressure drop principle, so the more pressure drop it gets, the more fluid it can pass through.
At WOT (Wide Open Throttle) the "straw" is now equivalent to a Pringle's tube, so all the air passes through with minimum restriction, as a result the vacuum drops to almost 0". The Venturi still provides enough fuel because the lack of pressure is compensated for by a higher volume of air passing by it.
Why is it that fuel consumption increases when carb heat is on? Surely less dense air requires less fuel to maintain the same ratio?
Thanks!
look like egr exaust gas to intake back.
Where does the alternate air comes from? The unfiltered one.
Hi there, that's a good question. It depends on the aircraft types, but usually inside the engine cowling.
@@flightclubonline the cowling flaps?
@@Ahmed-cn6hj cowling section
Why do so many aircraft engines even today have a carburetor instead of direct injection?
There are many advantages to Fuel Injection, such as increased efficiency but carburettors are cheaper to manufacture, make hot engine starts easier and are less prone to issues with fuel contamination.
Please be 100 percent accurate, if you are going to teach. The carburetor will not be in the line of sight of a pilot, if on top! That's a lie. 2nd, the reason the carburetor is not on top of the engine is incase there is a fuel leak and that fuel could spill all over a hot engine igniting it, and turning it into a fireball.
Wow your really smart