Carburator Heat

[MAKG1]

http://www.rogermwilcox.com/darksucker.html

Now THAT brings back some memories. Thanks for the chuckle.

Doc, you're 100% right, layman or not. Cold is just lack of heat, like darkness is lack of light.

I suspect the guy who said otherwise heard the standard physics 101 description of "caloric" (Google that -- it's an interesting story) and got confused. It's true that heat isn't a substance. But it is indeed a "noun." It can be stored, manipulated, measured in BTU, etc., and is as real as any other form of energy. What you can't do is weigh it. But you can't weigh kinetic energy either.

 

[Dan Thomas]

That's why one should keep the heat riser repaired. It seems almost everyone with a carb neglects that.

Lots of guys used to customize their cars with those fancy chromed air cleaners that exposed the filter all the way around for "better breathing." In the course of that, the carb heat hose was tossed out, along with the original air cleaner housing and its vacuum-operated control valve.

And so they often had doggy performance and couldn't figure out why.

Dan

 

[Dan Thomas]

You think all nouns are tangible? Please don't tell me you learned grammar from Schoolhouse Rock.

Is "knowledge" a noun? Heat is a "thing" in the same sense. Good luck trying to mail a "centimeter" or a "concept."

Much of physics education is dealing with abstract concepts. They are just as real as tangibles; they have measurable effects, but they are not objects you can hold.

Grammar is not understanding. Do you know what heat is? At least the standard statistical mechanics definition?

Seems to me that there's some heat being generated in this thread. is there a measurement for it?

Dan

 

[Dan Thomas]

If you were idle throttle for awhile that would make sense.. probably the exhaust header temps fell quite a bit after being at idle for awhile - which would be like partially applying carb heat, which as we know can cause or even worsen ice formation

I don't know about the US, but in Canada the standard teaching procedure for forced approaches includes an opening of the throttle for a time at every thousand feet of altitude lost, to warm up those pipes and make some heat for the carb, which of course has its carb heat on. The FIRST thing one does when the engine quits is to pull that knob.

But as I told my students, three seconds of throttle isn't going to do it. Those pipes get pretty cool in the glide, and more a few seconds of exhaust flame is required to heat the pipes so that the carb air gets hot enough for long enough to remove any ice that may have formed. Many instructors don't like that idea, since it stretches the glide and makes it much easier for the student to make the target field, but that's better than having a real engine-out situation, which occurs all too frequently during PFLs due to carb icing.

And sometimes, in cold weather, the engine just gets too cold in the glide and fails to respond when the student opens the throttle again to overshoot, and especially if he opens it too fast.

Dan

 

[Dan Thomas]

If you were idle throttle for awhile that would make sense.. probably the exhaust header temps fell quite a bit after being at idle for awhile - which would be like partially applying carb heat, which as we know can cause or even worsen ice formation

Or using carb heat while flying in ice crystals at temps below -20°C, at which temp there is no ice threat at all since all atmospheric moisture has frozen (making the airborne ice crystals) or the air is so dry that there's not enough moisture in any form. Carb ice can melt those crystals (they're not filtered out when carb heat is on) and then they refreeze in the carb. In that case, carb heat can't remove the ice. Bad deal.

Dan

 

[kgruber]

Now THAT brings back some memories. Thanks for the chuckle.

Doc, you're 100% right, layman or not. Cold is just lack of heat, like darkness is lack of light.

I suspect the guy who said otherwise heard the standard physics 101 description of "caloric" (Google that -- it's an interesting story) and got confused. It's true that heat isn't a substance. But it is indeed a "noun." It can be stored, manipulated, measured in BTU, etc., and is as real as any other form of energy. What you can't do is weigh it. But you can't weigh kinetic energy either.

Good. Since you can store it, please send me some. Please send me the amount of heat I need to raise one pound of water one degree faharenheit.

 

[ChrisK]

Do you want a side of kinetic energy? Maybe..... A BOOT TO THE HEAD!!!

 

[PPC1052]

Good. Since you can store it, please send me some. Please send me the amount of heat I need to raise one pound of water one degree faharenheit.

You can do that yourself. Take some water, put it in the microwave and heat it up. If you want to be precise, take a pound, and heat it up 2 degrees above the pound of water you want to heat up by 1 degree. Then pour it into your pound of water. Voila! If you want to keep the two bodies of water seperate, you can do that, too. But you just have to account for the heat capacity of the container, and make sure the container will conduct the heat efficiently.

 

[kgruber]

You can do that yourself. Take some water, put it in the microwave and heat it up. If you want to be precise, take a pound, and heat it up 2 degrees above the pound of water you want to heat up by 1 degree. Then pour it into your pound of water. Voila! If you want to keep the two bodies of water seperate, you can do that, too. But you just have to account for the heat capacity of the container, and make sure the container will conduct the heat efficiently.

Thanks, but I don't want any water. All I want is some "heat." Since most here think and talk like it is a noun and actually IS something, please just package some of that "heat" up and send it to me.

When you open up a hot oven door and peer in, you may feel some hot air, but you quite definitely won't see or feel any heat.

 

[MDeitch1976]

Thanks, but I don't want any water. All I want is some "heat." Since most here think and talk like it is a noun and actually IS something, please just package some of that "heat" up and send it to me.

When you open up a hot oven door and peer in, you may feel some hot air, but you quite definitely won't see or feel any heat.

Your living in a world of heat. Already packaged up, and allowing you to have molecular motion. Without heat, molecules stop.
If you have water at 32*F, it will still be water until you remove 144 BTUs of Latent Heat, then it will turn to ice. You can deny the existence of heat all day long. Air Conditioning would not work. An air conditioner, takes heat from a place where it is objectionable, and moves it to a place where it is not objectionable.

 

[MAKG1]

When you open up a hot oven door and peer in, you may feel some hot air, but you quite definitely won't see or feel any heat.

You just HAVE to be a college freshman in his first class. Very unsophisticated (mis)understanding, with a lot of misplaced confidence.

Heat can be transported by conduction, radiation, or convection. Radiative transfer is, in a very real sense, "feeling" heat. It makes you get hotter with no direct contact. Though a light bulb (or especially a heat lamp or conventional toaster) is a better example than an oven. And unless your oven is convective (some are), most of the heat transfer is done by radiation, followed by conduction in the food.

Almost every college freshman has to figure out how much he doesn't know during the first few months. High school may have been easy -- it is for a lot of students in the sciences. But university is another story.

 

[PPC1052]

Thanks, but I don't want any water. All I want is some "heat." Since most here think and talk like it is a noun and actually IS something, please just package some of that "heat" up and send it to me.

When you open up a hot oven door and peer in, you may feel some hot air, but you quite definitely won't see or feel any heat.

All you asked was that someone send you some heat. I told you how you could send heat from your microwave to wherever you stored your pound of water. I can't help it you don't like my "packaging."

I don't want to fight you on your semantics issue of what a "noun" is. How about I just cite you to Webster's online. (that n. means it's a noun.)

http://www.webster-dictionary.org/definition/heat

 

[denverpilot]

There are plenty of "unable to be stored easily" nouns.

"Electromagnetic waves" is a plural noun (well, waves is a mown, and electromagnetic is an adjective describing the noun, anyway...) and they're even harder to store than heat.

The "send me some heat" argument doesn't hold up against the "heat is a noun" argument.

The word heat is capable of being a noun or a verb. Waves in this context is a noun, but can also be a verb. Light is a noun, but can also be a verb -- as another example. The list goes on forever.

If you don't like his use of the noun, or his argument that because the word can be used as a noun, the properties of heat can be treated as an object, that's fine... but it doesn't change that the word is a noun in certain contexts.

 

[gismo]

But it is indeed a "noun." It can be stored, manipulated, measured in BTU, etc., and is as real as any other form of energy. What you can't do is weigh it. But you can't weigh kinetic energy either.

Well if you had enough you ought to be able to weigh it, E=MC^2 and all. But I suspect it would have to be really hot to register on any plausible weighing device. Then again we've been able to measure the mass of a photon which only exists when it's moving at C (or did we just calculate that?).

 

[MAKG1]

You can talk about "equivalent mass" of photons, but their mass is a function of frequency. And photons are not conserved; they can be created and destroyed providing the total energy is conserved.

There are several ways that heat can be treated in this manner -- in crystalline solids, heat can form particle-like excitations called "phonons" that behave quite a lot like photons.

At least for photons, equivalent mass doesn't really tell you much, but the energy does. While you can't directly weigh a photon, the closely related energy shift of falling photons has been measured several times.

Be careful -- E=MC^2 is only true if momentum is zero, and it usually isn't (the real equation without the usual misquote is E^2 - p^2 c^2 = m^2 c^4). And it's not really true at all for photons (though there is nothing wrong with defining it that way -- it just doesn't give you any new information). For them, the energy is h*frequency, where h is Planck's constant.

 

[kgruber]

There are plenty of "unable to be stored easily" nouns.

"Electromagnetic waves" is a plural noun (well, waves is a mown, and electromagnetic is an adjective describing the noun, anyway...) and they're even harder to store than heat.

The "send me some heat" argument doesn't hold up against the "heat is a noun" argument.

The word heat is capable of being a noun or a verb. Waves in this context is a noun, but can also be a verb. Light is a noun, but can also be a verb -- as another example. The list goes on forever.

If you don't like his use of the noun, or his argument that because the word can be used as a noun, the properties of heat can be treated as an object, that's fine... but it doesn't change that the word is a noun in certain contexts.

That arguement reminds me of fellow engineers who sat their fat butts around, slobbering over their sliderule, while jamming another messy pen into their plastic pocket protector.

While being around those slobs was a real treat, you'd find me out in the Cub I took to school......usually with what's her name.

You can futz around with all you fancy energy equations, but in the end, when you open up the oven, there is no heat in there. Nor can you send me any.

 

[Tom-D]

That arguement reminds me of fellow engineers who sat their fat butts around, slobbering over their sliderule, while jamming another messy pen into their plastic pocket protector.

While being around those slobs was a real treat, you'd find me out in the Cub I took to school......usually with what's her name.

You can futz around with all you fancy energy equations, but in the end, when you open up the oven, there is no heat in there. Nor can you send me any.

Do you need another bottle?
http://www.monticellodrug.com/products/heet.html

 

[MAKG1]

That arguement reminds me of fellow engineers who sat their fat butts around, slobbering over their sliderule, while jamming another messy pen into their plastic pocket protector.

While being around those slobs was a real treat, you'd find me out in the Cub I took to school......usually with what's her name.

You can futz around with all you fancy energy equations, but in the end, when you open up the oven, there is no heat in there. Nor can you send me any.

OK, I'm calling you on this.

Poser. You're no engineer. At the very least, you haven't been one for multiple decades and are quite rusty. More likely, your "experience" with engineers comes from watching The Right Stuff and other movies that deal with stereotypes. We're not all named Poindexter either. We don't wear broken safety glasses. Most of us don't own slide rules, and those few of us that do treat them more as curiosities. The desktop calculator was invented in the 70s, and engineers were the first customers.

A handful of the engineers I work with date back to the Apollo days. While they might have worn pocket protectors 40 years ago, they don't now and have never been "fat slobs," and a surprisingly large number of them are or have been private pilots. And if you think propulsion engineers don't understand heat, there really is no help for you.

 

[pilot_dude]

Doc, you're 100% right, layman or not. Cold is just lack of heat, like darkness is lack of light.

And light is the lack of Lucas

 

[airguy]

"heat" is not a noun. There is no such thing as "heat." If you open an oven door and look in there is no "heat" in there. There IS high temperature air.

And if you really want to get picky about it, there is no "temperature" either. Temperature is simply a handy yardstick that we invented as a means of measuring the relative kinetic energy of the molecules of a substance in their random Brownian motion.

 

[MDeitch1976]

I guess when I take my check ride, I can tell the examiner that heat doesn't exist. Therefore the carb heat is irrelevant. Until, they install a thermal energy control I am screwed.

 

[airguy]

You would be correct, and he would still stay you are wrong. Pointing out to a government employee that they are both wrong and uneducated will not go well for you in this scenario.