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Trailer Tires Overheating.
Rod McInnis wrote:
"basskisser" wrote in message om... That has absolutely nothing to do with the fact that that nitrogen doesn't expand at the same rate as oxygen for any given temperature change. Do you deny this? Yes. I deny this. Mr. Boyle denies this. Mr. Charles denies this. Mr. Gay and Mr. Lussac deny this. They wrote laws of physics about it. Every chemistry, physics and thermodynamics class uses these laws. Here, don't take my word for it, let's take a look at some of the information available from the net. As an example: Department of Chemistry California State University, Sacramento http://kekule.chem.csus.edu/gaslaws You might as well give up now. No matter how much proof you provide, basskisser will not believe it and will find some way to weasel out, probably by saying he answered you in some other post without being able to show where. The thing I find amazing is that he claims to be a structural engineer, or something like that. A professional engineer even. He is a sad testament to whatever college he graduated from. This is basic high school physics that is also reempasized in first year college engineering physics. For him to be so blatently wrong in something that is so provable that he's wrong and still not be able to admit it is just plain sad. Steve |
Trailer Tires Overheating.
"Del Cecchi" wrote in message ... "Mark Browne" wrote in message news:qv8ob.62616$Tr4.167581@attbi_s03... snip That has absolutely nothing to do with the fact that that nitrogen doesn't expand at the same rate as oxygen for any given temperature change. Do you deny this? snip Now you have my curiosity! I understand all gases to expand about 1/270 per degree C at room temperature. Please explain how now nitrogen and oxygen differ? Mark Browne Nitrogen has an atomic weight of 14 and oxygen is 16? I can live on pure oxygen, but pure nitrogen will kill me? By the way, is is more like 1/300 at room temperature unless you live in a very cold room.... :-) PV=nRT or PV=NkT del cecchi Thanks. Mark Browne |
Trailer Tires Overheating.
(Steven Shelikoff) wrote in message ...
On 30 Oct 2003 04:21:49 -0800, (basskisser) wrote: (Steven Shelikoff) wrote in message ... On 29 Oct 2003 04:27:31 -0800, (basskisser) wrote: Please refute my statements, or shut up. Quit stalking me. lol. Stalking you? I didn't even respond to you. You're so stupid you can't even follow a thread. Idiot. If you aren't stalking me, why did you bother to refer to me in a response that had NOTHING to do with the topic? You're inability to follow a thread and know what's on topic vs. off topic is only surpassed by your inability to understand the most basic of engineering concepts. Steve Again, do you have something of substance to interject into the thread, or just stalking? This thread is about trailer tires overheating. Now, what have you posted in this thread, relating to the subject? Hell, I'll answer for you. NOTHING. |
Trailer Tires Overheating.
Steven Shelikoff wrote in message ...
Rod McInnis wrote: "basskisser" wrote in message om... That has absolutely nothing to do with the fact that that nitrogen doesn't expand at the same rate as oxygen for any given temperature change. Do you deny this? Yes. I deny this. Mr. Boyle denies this. Mr. Charles denies this. Mr. Gay and Mr. Lussac deny this. They wrote laws of physics about it. Every chemistry, physics and thermodynamics class uses these laws. Here, don't take my word for it, let's take a look at some of the information available from the net. As an example: Department of Chemistry California State University, Sacramento http://kekule.chem.csus.edu/gaslaws You might as well give up now. No matter how much proof you provide, basskisser will not believe it and will find some way to weasel out, probably by saying he answered you in some other post without being able to show where. The thing I find amazing is that he claims to be a structural engineer, or something like that. A professional engineer even. He is a sad testament to whatever college he graduated from. This is basic high school physics that is also reempasized in first year college engineering physics. For him to be so blatently wrong in something that is so provable that he's wrong and still not be able to admit it is just plain sad. Steve Boyles' law states that for a GIVEN GAS, the rate of expansion versus temperature is inversely proportional. FOR A GIVEN GAS. It does not state, however, that one gas expands as temp. increases, at the same rate as another gas. |
Trailer Tires Overheating.
Rick wrote in message link.net...
Mark Browne wrote: Now you have my curiosity! I understand all gases to expand about 1/270 per degree C at room temperature. Please explain how now nitrogen and oxygen differ? This should be a good one ... but don't hold your breath waiting for a response. I am just amazed that he doesn't just look up the gas laws and see for himself. Bizarre. Bass posted this and I haven't heard from him since I answered him, so if you attempt to explain it to him maybe he will finally just go away. You apparently don't know squat about the Laws of Gases. Now, Im again telling you that the ONLY reason is that the pressure to temperature ratio is more linear. Do you refute that? If so, do tell why. Now, I suspect that you don't UNDERSTAND my answer, and that is the reason that you don't think it's correct. So, allow me to explain. The nitrogen doesn't expand as much as air, for a given temperature change. The level of scientific illiteracy in this country is frightening when you see it defended so hotly by those with the smallest armory. Rick Yes, I agree, the level of scientific illiteracy is frightening. Here you go, and Shelikoff, can you read this and comment?? There are several properties of gasses that can easily be demonstrated using liquid nitrogen. These properties include phase changes (gas to liquid, liquid to gas, and visa versa), and the temperature dependence of volume. If you have a volunteer blow up a clear balloon, you can show how a gas (oxygen) can go from gas to liquid. Oxygen has a boiling point of -180o C, so when the balloon containing oxygen from someone's breath is submerged in the liquid nitrogen the oxygen is cooled to below its boiling point and it begins to condense. There is usually some water vapor present in this balloon also- under good conditions, the water vapor will condense to liquid and then freeze, thus going through two phase changes. You can also discuss the kinetics involved in the balloons expanding when they are removed from the liquid nitrogen and begin to return to room temperature. Notice how the lighter gasses do not constrict as much since the boiling points of hydrogen and helium are both lower than that of nitrogen. You may also notice though that they will also expand a bit faster than the heavier gasses. The differences in the expansion rate becomes even more obvious if argon is available. Argon has a very small difference between the freezing point and boiling point (4o C) thus an argon filled balloon will expand very rapidly. Compare this to a breath filled balloon or a balloon filled with a gas such as ethane (95o C difference between freezing and boiling points). |
Trailer Tires Overheating.
"basskisser" wrote in message om... Rick wrote in message link.net... Mark Browne wrote: Now you have my curiosity! I understand all gases to expand about 1/270 per degree C at room temperature. Please explain how now nitrogen and oxygen differ? This should be a good one ... but don't hold your breath waiting for a response. I am just amazed that he doesn't just look up the gas laws and see for himself. Bizarre. Bass posted this and I haven't heard from him since I answered him, so if you attempt to explain it to him maybe he will finally just go away. You apparently don't know squat about the Laws of Gases. Now, Im again telling you that the ONLY reason is that the pressure to temperature ratio is more linear. Do you refute that? If so, do tell why. Now, I suspect that you don't UNDERSTAND my answer, and that is the reason that you don't think it's correct. So, allow me to explain. The nitrogen doesn't expand as much as air, for a given temperature change. The level of scientific illiteracy in this country is frightening when you see it defended so hotly by those with the smallest armory. Rick Yes, I agree, the level of scientific illiteracy is frightening. Here you go, and Shelikoff, can you read this and comment?? There are several properties of gasses that can easily be demonstrated using liquid nitrogen. These properties include phase changes (gas to liquid, liquid to gas, and visa versa), and the temperature dependence of volume. If you have a volunteer blow up a clear balloon, you can show how a gas (oxygen) can go from gas to liquid. Oxygen has a boiling point of -180o C, so when the balloon containing oxygen from someone's breath is submerged in the liquid nitrogen the oxygen is cooled to below its boiling point and it begins to condense. There is usually some water vapor present in this balloon also- under good conditions, the water vapor will condense to liquid and then freeze, thus going through two phase changes. You can also discuss the kinetics involved in the balloons expanding when they are removed from the liquid nitrogen and begin to return to room temperature. Notice how the lighter gasses do not constrict as much since the boiling points of hydrogen and helium are both lower than that of nitrogen. You may also notice though that they will also expand a bit faster than the heavier gasses. The differences in the expansion rate becomes even more obvious if argon is available. Argon has a very small difference between the freezing point and boiling point (4o C) thus an argon filled balloon will expand very rapidly. Compare this to a breath filled balloon or a balloon filled with a gas such as ethane (95o C difference between freezing and boiling points). Rick and I just worked this out for water. In a race car tire that reaches 225 F to 250 F during normal operation, there *is* a phase change in water, from liquid to vapor. The newly introduced water vapor can add a significant component to the partial pressure composition of the tire. The only thing left here is to determine how much liquid water might be found inside a tire in different settings. Now in the temperature range of interest, operating tire temperatures, are any of the materials you mention (Nitrogen, Argon, Oxygen) undergoing any phase changes? If not, do they show any appreciable deviation from the ideal gas properties in the temperature range of interest? If not, suck it up and move on. Mark Browne P. S. You would not be doing a Jax here, would you? That is, trying to define the problem in such a narrow way as to give yourself a little wiggle room. This is not necessarily a bad thing - some us miss toying with Jax! |
Trailer Tires Overheating.
"basskisser" wrote in message om... Steven Shelikoff wrote in message ... Rod McInnis wrote: "basskisser" wrote in message om... That has absolutely nothing to do with the fact that that nitrogen doesn't expand at the same rate as oxygen for any given temperature change. Do you deny this? Yes. I deny this. Mr. Boyle denies this. Mr. Charles denies this. Mr. Gay and Mr. Lussac deny this. They wrote laws of physics about it. Every chemistry, physics and thermodynamics class uses these laws. Here, don't take my word for it, let's take a look at some of the information available from the net. As an example: Department of Chemistry California State University, Sacramento http://kekule.chem.csus.edu/gaslaws You might as well give up now. No matter how much proof you provide, basskisser will not believe it and will find some way to weasel out, probably by saying he answered you in some other post without being able to show where. The thing I find amazing is that he claims to be a structural engineer, or something like that. A professional engineer even. He is a sad testament to whatever college he graduated from. This is basic high school physics that is also reempasized in first year college engineering physics. For him to be so blatently wrong in something that is so provable that he's wrong and still not be able to admit it is just plain sad. Steve Boyles' law states that for a GIVEN GAS, the rate of expansion versus temperature is inversely proportional. FOR A GIVEN GAS. It does not state, however, that one gas expands as temp. increases, at the same rate as another gas. Ok, since you are running your class here, which law *does* state that "one gas expands as temperature increases, at the same rate as another gas." Mark Browne |
Trailer Tires Overheating.
On 31 Oct 2003 04:46:29 -0800, (basskisser) wrote:
(Steven Shelikoff) wrote in message ... On 30 Oct 2003 04:21:49 -0800, (basskisser) wrote: (Steven Shelikoff) wrote in message ... On 29 Oct 2003 04:27:31 -0800, (basskisser) wrote: Please refute my statements, or shut up. Quit stalking me. lol. Stalking you? I didn't even respond to you. You're so stupid you can't even follow a thread. Idiot. If you aren't stalking me, why did you bother to refer to me in a response that had NOTHING to do with the topic? You're inability to follow a thread and know what's on topic vs. off topic is only surpassed by your inability to understand the most basic of engineering concepts. Again, do you have something of substance to interject into the thread, or just stalking? This thread is about trailer tires overheating. Now, what have you posted in this thread, relating to the subject? Hell, I'll answer for you. NOTHING. As usual, you're wrong again. I've contributed by pointing out that you're full of crap when you say that nitrogen and oxygen don't expand at the same rate for a given temperature change. And you're completely full of crap when you say that the temperature vs. pressure curve for air is somehow less linear than for nitrogen. I know that these are such simple basic concepts (any high school physics student would laugh at you if they read it) that I should not have to correct you on such stupid statements. But you're just ****ed that once again, you're displaying your intellectual ineptitude. And this time there are several people witnessing it and having a good chuckle at your expense. So now what? Are you going to threaten me again for pointing out what a moron you are? Steve |
Trailer Tires Overheating.
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Trailer Tires Overheating.
On 31 Oct 2003 04:49:23 -0800, (basskisser) wrote:
Steven Shelikoff wrote in message ... Rod McInnis wrote: "basskisser" wrote in message om... That has absolutely nothing to do with the fact that that nitrogen doesn't expand at the same rate as oxygen for any given temperature change. Do you deny this? Yes. I deny this. Mr. Boyle denies this. Mr. Charles denies this. Mr. Gay and Mr. Lussac deny this. They wrote laws of physics about it. Every chemistry, physics and thermodynamics class uses these laws. Here, don't take my word for it, let's take a look at some of the information available from the net. As an example: Department of Chemistry California State University, Sacramento http://kekule.chem.csus.edu/gaslaws You might as well give up now. No matter how much proof you provide, basskisser will not believe it and will find some way to weasel out, probably by saying he answered you in some other post without being able to show where. The thing I find amazing is that he claims to be a structural engineer, or something like that. A professional engineer even. He is a sad testament to whatever college he graduated from. This is basic high school physics that is also reempasized in first year college engineering physics. For him to be so blatently wrong in something that is so provable that he's wrong and still not be able to admit it is just plain sad. Boyles' law states that for a GIVEN GAS, the rate of expansion versus temperature is inversely proportional. FOR A GIVEN GAS. It does not state, however, that one gas expands as temp. increases, at the same rate as another gas. Very good. Now look up Charles' Law, V1/T1=V2/T2. Then the ideal gas law, PV=nRT. And note that at low pressures (i.e., the pressures at which are normally inside tires) all gasses act like ideal gasses and have the SAME pressure vs. temperature vs. volume relationship.. Your phase change argument elsewhere is complete crap if it's meant to show that nitrogen has a different PVT relationship vs. oxygen vs. air at the pressures we're discussing. Now, I'll be nice and give you a hint on how you could possibly defend your statement about air having a less linear pressure temperature relationship then nitrogen: Look up how much more or less ideal air is vs. nitrogen. But even that argument has a problem in that 1) both of them behave like an ideal gas at the low pressures we're talking about, where the molecules are still far enough apart that their attraction doesn't change the linear relationship PV=nRT. And 2) air is mostly nitrogen anyway. So if you put both of them at a pressure where they deviate from the ideal gas law (a very high pressure that would blow up most storage tanks let alone any tire) they would both deviate from the ideal gas law almost equally. Keep trying. Steve |
Trailer Tires Overheating.
On Fri, 31 Oct 2003 13:55:55 GMT, "Mark Browne"
wrote: Rick and I just worked this out for water. In a race car tire that reaches 225 F to 250 F during normal operation, there *is* a phase change in water, from liquid to vapor. The newly introduced water vapor can add a significant component to the partial pressure composition of the tire. The only thing left here is to determine how much liquid water might be found inside a tire in different settings. If there's any liquid water in the race tire/wheel at all, the tire filler and wheel balancer should be fired. At the speed those tires rotate, even a small amount of liquid water (say a few grams) would be noticed as a vibration because the tire would be out of balance. It doesn't get spread evenly around the inside of the tire. Now in the temperature range of interest, operating tire temperatures, are any of the materials you mention (Nitrogen, Argon, Oxygen) undergoing any phase changes? If not, do they show any appreciable deviation from the ideal gas properties in the temperature range of interest? It's pressure as well as temperature that would cause them to deviate from ideal gas properties. And the pressures are not high enough. Typically, you have to go above around 150 psi to notice any deviation from the ideal gas laws. You have to go much higher than that for it to have any appreciable effect. As far as temperature is concerned, they deviate from ideal gas properties at very low temperatures, temps near the phase change to liquid. The higher the temp, the more ideal the gas behaves. If you're only a few degress away from the phase change, you won't notice any deviation from the ideal gas laws.. There is one other way a gas can deviate from the gas laws, and that's at very small volumes. But the container must be so small that the volume of the gas molecules themselves must be a significant portion of the container. That is not the case with a tire. If not, suck it up and move on. Mark Browne P. S. You would not be doing a Jax here, would you? That is, trying to define the problem in such a narrow way as to give yourself a little wiggle room. This is not necessarily a bad thing - some us miss toying with Jax! At first, I thought he was Jax. But Jax at least had the courtesy to confine the things he was wrong about to on-topic subjects. This idiot is all over the spectrum. Steve |
Trailer Tires Overheating.
basskisser wrote:
Yes, I agree, the level of scientific illiteracy is frightening. Here you go, and Shelikoff, can you read this and comment?? There are several properties of gasses that can easily be demonstrated using liquid nitrogen. These properties include phase changes (gas to liquid, liquid to gas, and visa versa) There isn't much new that can be added to your posts on this subject. I first thought you were just argumentative and not too bright but now I see that you are both argumentative and really stupid as well as curse with a very short attention span and an obvious learning disability. If you will reread or have someone read to you my post of October 28 at 8:56am message ID . net you may gain a glimpse of the fact that this has already been pointed out as a possibility for your inability to comprehend the subject. Here it is again just in case you can't find the original. ------------------------------ I think most of this nonsense about nitrogen in tires not expanding as much as air comes from the fact that few people really understand the properties of gases. There is a little phrase in the gas laws that refers to "phase change" ... that is where the followers of the myth may be running aground - (boating content). Liquid nitrogen will vaporize to produce a volume of gas that occupies about 700 times that of the liquid. Liquid oxygen will vaporize to produce a gas that occupies around 860 times the volume. Vaporization is the phase change. Once the liquid has evaporated the resultant gas, nitrogen, oxygen, or water vapor, will follow the gas laws and when the correct law is applied (there are several) the properties of those gases are very predictable and if you understood them you would see that the properties of those gases are identical in their behavior under the conditions which race car teams and trailer boaters operate. ------------------------------- I give up Basskisser, it has become obvious you are not really interested in learning anything but are simply looking for a fight, trolling, or just too thick to benefit from a discussion in which you are ill equipped to participate. Rick |
Trailer Tires Overheating.
"basskisser" wrote in message om... There are several properties of gasses that can easily be demonstrated using liquid nitrogen. As I clearly stated, the ideal gas laws apply as long as you are NOT operating in the temperature/pressure ranges that will result in a phase change for the elements involved. For the pressure and temperature that a tire will be exposed to the gas laws apply. Once you start talking about liquid nitrogen we are clearly in the phase change realm. You may also notice though that they will also expand a bit faster than the heavier gasses. No. They have a lower boiling point, and thus as you watch them react with the surroundings they will start boiling sooner. It takes a significant amount of engergy to make an element/compond change state. Start with a mixture of elements/componds (assuming that they don't react and form a new compond) that are all cooled below any of their boiling points (the insertion into the liquid nitrogen) and then start adding energy (remove it from the nitrogen, it absorbs energy from the surrounding air). Track the temperature of the mixture over time. You will see a fairly rapid and linear rise in temperature until it reaches a temperature where one of the elments/componds changes state. At this point the temperature will remain constant until all of the element has changed state. The temperature will increase linearly again until the next state change temperature is reached. If you are comparing the rate at which such an experiment will inflate a balloon, then a mixture that has an element/compond that changes state at a lower temperature will certainly start inflating sooner and do it more rapidly. This isn't a function of the gas, it is a function of the stage change. The differences in the expansion rate becomes even more obvious if argon is available. Argon has a very small difference between the freezing point and boiling point (4o C) thus an argon filled balloon will expand very rapidly. All elements/compounds expand as they transition into the gaseos state. This is not universally true for the transition from solid to liquid. Many elements/compounds, including water, have a "triple point", a temperature/pressure combination that will allow all three phases to exist at the same time. Predicting the exact expansion rates of a mixture where multiple state changes are involved is a bit more tedious, although the expansion between solid and liquid would be dramatically less than between liquid/solid and gas. Compare this to a breath filled balloon or a balloon filled with a gas such as ethane Stay above the boiling point of ethane and these two will behave the same. Heat both balloons the same amount and they will both expand the same amount. Now, there is one characteristic that might lead you to a false conclusion, and that is the rate at which the change occurs. If you took the two balloons from a cool room into a warm room you might see one of the balloons expand faster than the other. Leave them there until they reach equilibrium, however, and they will both expand the same. This is due to the thermal resistance. Just like aluminum heats up faster than iron. Back to what I have been saying all along: PV=nRT. It works for the temperatures and pressures that a tire will be operated at. It doesn't matter what the gas is. If the volume stays constant, and you change the T by x%, you change the pressure by x%. It is basic gas law, you should have learned this in high school chemistry class. |
Trailer Tires Overheating.
"Del Cecchi" wrote in message ...
Please explain how now nitrogen and oxygen differ? Mark Browne Nitrogen has an atomic weight of 14 and oxygen is 16? I can live on pure oxygen, but pure nitrogen will kill me? Not only that..... The nitrogen in normal "air" is responsible for a real strong "buzz" (nitrogen narcosis, rapture of the deep, ect) when scuba diving below depths of 130'. Too much oxygen at depth and you can die (Ox Tox). Got to add a little some helium (15-30%) while removing same amount of nitrogen to alleviate those little "problems" when deep diving. Has anyone pointed out to "basskisser" the "air" we breath is 79% nitrogen and 21% oxygen? -- SJM |
Trailer Tires Overheating.
Hydrogen is even better yet (better heat transfer coefficient). It is what is
used to cool the 1000 megawatt generators at power plants as air can't carry the heat from resistance in the windings away fast enough. Just watch out for flames or sparks. Also hydrogen tends to diffuse through the tire so you have to replenish it more often. JJ On Sun, 26 Oct 2003 00:00:08 GMT, "Lawrence James" wrote: They have it at race tracks. Otherwise you need a tank of it. Know anyone in the hvac business, they use it to purge refrigerant lines while they braze. Not really likely to help enouhg to be worth the trouble though. The other posters are right, bigger wheels are the right solution. "John Gaquin" wrote in message ... "Wwj2110" wrote in message nitrogen helps tires run cooler How does that work? JG James Johnson remove the "dot" from after sail in email address to reply |
Trailer Tires Overheating.
On Sun, 02 Nov 2003 00:31:47 +0000, James Johnson wrote:
Hydrogen is even better yet (better heat transfer coefficient). It is what is used to cool the 1000 megawatt generators at power plants as air can't carry the heat from resistance in the windings away fast enough. Just watch out for flames or sparks. Also hydrogen tends to diffuse through the tire so you have to replenish it more often. Having worked in a 1000 MW generating station, I can safely say this is doggie-donuts. I wouldn't have hydrogen (or any explosive gas) within 100ft of a high-power generator! Lloyd Sumpter |
Trailer Tires Overheating.
Lloyd Sumpter wrote:
Having worked in a 1000 MW generating station, I can safely say this is doggie-donuts. I wouldn't have hydrogen (or any explosive gas) within 100ft of a high-power generator! Hydrogen cooling is pretty common. He isn't, however, thinking about just where that heat in a tire is supposed to go. It's not like there is a heat exchanger to remove the heat from the gas that was heated by the rubber surrounding that gas to begin with. Rick |
Trailer Tires Overheating.
On Sun, 02 Nov 2003 19:48:12 GMT, Rick wrote:
Lloyd Sumpter wrote: Having worked in a 1000 MW generating station, I can safely say this is doggie-donuts. I wouldn't have hydrogen (or any explosive gas) within 100ft of a high-power generator! Hydrogen cooling is pretty common. He isn't, however, thinking about just where that heat in a tire is supposed to go. It's not like there is a heat exchanger to remove the heat from the gas that was heated by the rubber surrounding that gas to begin with. The wheel. I can see how the heat conductive properties of the gas can make a difference conducting heat from the tire to the wheel at different rates. Especially since the rubber itself isn't a good heat conductor. Steve |
Trailer Tires Overheating.
Steven Shelikoff wrote:
The wheel. The area of the wheel exposed to the gas is so small compared to the area of the tire producing the heat that I doubt it has much of any practical value in dissipation of heat above and beyond air flow over and radiation from the tire itself. Though it doesn't apply much to boat trailer tires, the heat conductivity of the gas would work against tire cooling in the case of race cars and aircraft since it would serve to increase the rate of tire heating in heavy brake application. Many aircraft tire failures are due to overheated brakes, heating the wheels to the point of causing the tires to blow out or burn, not from heat generated by the tires themselves. Rick |
Trailer Tires Overheating.
On Mon, 03 Nov 2003 00:20:28 GMT, Rick wrote:
Steven Shelikoff wrote: The wheel. The area of the wheel exposed to the gas is so small compared to the area of the tire producing the heat that I doubt it has much of any practical value in dissipation of heat above and beyond air flow over and radiation from the tire itself. Actually, the area of the wheel exposed to the gas in a race car tire is pretty large compared to the area of the tire since they are wide and low profile. A narrow, high profile trailer tire doesn't have very much wheel exposed to the gas for the amount of tire area producing heat. Though it doesn't apply much to boat trailer tires, the heat conductivity of the gas would work against tire cooling in the case of race cars and aircraft since it would serve to increase the rate of tire heating in heavy brake application. Many aircraft tire failures are due Of course it all depends on the type of racing. During most racing like road racing, twisty corners, etc, heavy braking is applied but for very short durations. Superspeedway racing, not at all. There's plenty of cooling air ducted to the brakes and the rest of the suspension components can also act like a heat sink since they are directly attached to the brakes and wheel. On the other hand, the tires are always generating heat whenever the car is moving, and especially in turns. Heat is the enemy of tire life and whatever can be done to take away more heat from the tire will help. That being said, I sure wouldn't want hydrogen in my tires.:) to overheated brakes, heating the wheels to the point of causing the tires to blow out or burn, not from heat generated by the tires themselves. Slowing a 747 from 180 mph to taxi speed is hardly the same thing as bleeding off 40 or 50 mph from a super light race car. There's a whole different set of braking requirements, and aircraft brakes are in many cases under engineered since they depend so much on engine braking to slow down. Steve |
Trailer Tires Overheating.
Steven Shelikoff, the racing expert wrote:
Actually, the area of the wheel exposed to the gas in a race car tire is pretty large compared to the area of the tire since they are wide and low profile. Not in all types of racing. Actually, in some types, the narrower the better, less contact area, less friction. Take a salt flat racer, for instance. Though it doesn't apply much to boat trailer tires, the heat conductivity of the gas would work against tire cooling in the case of race cars and aircraft since it would serve to increase the rate of tire heating in heavy brake application. Many aircraft tire failures are due Of course it all depends on the type of racing. During most racing like road racing, twisty corners, etc, heavy braking is applied but for very short durations. Superspeedway racing, not at all. Are you really trying to say that on superspeedways, they don't use brakes at all? That's pretty stupid. They actually use brakes as opposed to letting off the throttle, trying to keep the enginer RPM's up. It takes forever to get those restictor plate engines back up to speed. They do, however, use completely different brake setups, smaller rotors, pads. These smaller, thinner rotors will get quite hot, quite quickly. There's plenty of cooling air ducted to the brakes and the rest of the suspension components can also act like a heat sink since they are directly attached to the brakes and wheel. On the other hand, the tires are always generating heat whenever the car is moving, and especially in turns. Heat is the enemy of tire life and whatever can be done to take away more heat from the tire will help. That being said, I sure wouldn't want hydrogen in my tires.:) Now that I can agree with. |
Trailer Tires Overheating.
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Trailer Tires Overheating.
Steven Shelikoff wrote:
aircraft brakes are in many cases under engineered since they depend so much on engine braking to slow down. Incorrect. The brakes on transport category aircraft are certified to stop the aircraft on the runway remaining after a rejected takeoff at the highest speed it would still be on the ground (V1) without using thrust reversers. Thrust reversers provide little braking at high speeds anyway. Rick |
Trailer Tires Overheating.
"basskisser" wrote in message om... They actually use brakes as opposed to letting off the throttle, trying to keep the enginer RPM's up. It takes forever to get those restictor plate engines back up to speed. Can you explain that statement? Unless your referring to the go karts you rent at the amusment center I don't understand how you can maintain engine RPMs and slow the car down. Automatic transmission?? Hmmmm..... Seen it on off road cars, I wasn't aware of it being very common on any sort of track or pavement vehicles. Without some sort of a slip clutch or torque converter, the engine RPM is going to be directly related to the velocity of the car. Rod |
Trailer Tires Overheating.
"Rod McInnis" wrote in message ... "basskisser" wrote in message om... They actually use brakes as opposed to letting off the throttle, trying to keep the enginer RPM's up. It takes forever to get those restictor plate engines back up to speed. Can you explain that statement? Unless your referring to the go karts you rent at the amusment center I don't understand how you can maintain engine RPMs and slow the car down. Automatic transmission?? Hmmmm..... Seen it on off road cars, I wasn't aware of it being very common on any sort of track or pavement vehicles. Without some sort of a slip clutch or torque converter, the engine RPM is going to be directly related to the velocity of the car. Rod He is confused. Brakes are noy used at the 2 NASCAR restrictor plate tracks (Daytona & Talladega). They simply run wide open through the turns on these tracks since there is enough banking (30 degrees) that they do not have to back off at all. |
Trailer Tires Overheating.
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Trailer Tires Overheating.
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Trailer Tires Overheating.
On Mon, 03 Nov 2003 17:11:20 GMT, Rick wrote:
Steven Shelikoff wrote: aircraft brakes are in many cases under engineered since they depend so much on engine braking to slow down. Incorrect. The brakes on transport category aircraft are certified to stop the aircraft on the runway remaining after a rejected takeoff at the highest speed it would still be on the ground (V1) without using thrust reversers. Thrust reversers provide little braking at high speeds anyway. Yeah, right.:) But not over and over and if that does happen, i.e., stopping the plane with the remaining runway after an aborted takeoff, you're almost guaranteed a brake fire. No matter how the brakes are certified, if a heavy gets up to takeoff speed on most runways, aborts and only has the brakes to stop it, chances are it's gonna go off the end of the runway. And I'm not sure where you get the idea that thrust reversers provide little braking at high speeds. They way they work, they really *only* provide braking at high speed and very little at low speed. They are the vast majority of braking at landing speed. While a jet thrust reverser can be used to back up the plane, very little thrust is actually "reversed". Mostly, it's just diverted into an unuseful direction, like up and down or outward, and very slightly forward for backing up. They slow the plane mostly by engine drag, not by reversing the thrust forward. And engine drag is greater at higher speeds. In fact, most of the accidents involving thrust reversers occur when they are inadvertantly or uncommanded deployed in flight, causing massive drag on the deployed side and throwing the plane out of control. Steve |
Trailer Tires Overheating.
"Rick" wrote in message ink.net... Steven Shelikoff wrote: aircraft brakes are in many cases under engineered since they depend so much on engine braking to slow down. Incorrect. The brakes on transport category aircraft are certified to stop the aircraft on the runway remaining after a rejected takeoff at the highest speed it would still be on the ground (V1) without using thrust reversers. Thrust reversers provide little braking at high speeds anyway. Rick The brakes *will* stop the plane at V1. Other than that, there may be problems. The company I work for sells parts for "retriever kits." They use these kits to recover aircraft after they deploy the brakes during an aborted takeoff. The heat from the brakes soak into the tires and cause various problems. See: http://www.maxwell.af.mil/msd/pubs/maxins/32-2004.pdf Note 4.3.4, time to tire failure after emergency braking operation is about 12 to 15 minutes. Mark Browne |
Trailer Tires Overheating.
Mark Browne wrote:
The brakes *will* stop the plane at V1. Other than that, there may be problems. The company I work for sells parts for "retriever kits." They use these kits to recover aircraft after they deploy the brakes during an aborted takeoff. The heat from the brakes soak into the tires and cause various problems. For you and Steve, please go back and read where I posted" Many aircraft tire failures are due to overheated brakes, heating the wheels to the point of causing the tires to blow out or burn, not from heat generated by the tires themselves. That was in reponse to a post that claimed the wheels would provide sufficient heat sinking to cool the tires. As an ATP and former airline captain I am very familiar with aircraft braking limitations. Rick |
Trailer Tires Overheating.
On Tue, 04 Nov 2003 05:18:29 GMT, Rick wrote:
Mark Browne wrote: The brakes *will* stop the plane at V1. Other than that, there may be problems. The company I work for sells parts for "retriever kits." They use these kits to recover aircraft after they deploy the brakes during an aborted takeoff. The heat from the brakes soak into the tires and cause various problems. For you and Steve, please go back and read where I posted" Many aircraft tire failures are due to overheated brakes, heating the wheels to the point of causing the tires to blow out or burn, not from heat generated by the tires themselves. That was in reponse to a post that claimed the wheels would provide sufficient heat sinking to cool the tires. Yes, I saw that and agree that when airliner brakes are used excessively they can cause tire blowouts. But again, the braking requirements and capabilities and the heating of the tires of an airliner vs. a race car couldn't be more different. To suggest that because airliner tire failures due to the brakes generating too much heat mean that race cars also can't dissapate their braking heat fast enough to prevent tire problems is a non sequitur. As an ATP and former airline captain I am very familiar with aircraft braking limitations. I'm surprised then to hear you say that thrust reversers provide little braking at high speeds when in reality, they provide most of their braking at high speeds and much less at low speeds. That's why, when an airliner lands, they'll use the thrust reversers first, while the plane is going fast. Then once it slows down sufficiently, they'll use more of the brakes. Steve |
Trailer Tires Overheating.
On Sun, 02 Nov 2003 11:05:12 -0800, "Lloyd Sumpter" wrote:
On Sun, 02 Nov 2003 00:31:47 +0000, James Johnson wrote: Hydrogen is even better yet (better heat transfer coefficient). It is what is used to cool the 1000 megawatt generators at power plants as air can't carry the heat from resistance in the windings away fast enough. Just watch out for flames or sparks. Also hydrogen tends to diffuse through the tire so you have to replenish it more often. I've worked at Perry, OH; Enrico Fermi, MI; Calvert Cliffs, MD; Oyster Creek, NJ; Salem, NJ; Peach Bottom, PA as a contractor for maintenance outages and as part of the operating staff for 2 of them. They ranged from 600 MW to 1300 MW. In all of these the internal cooling for the generator was recirculating gaseous hydrogen. The H2 is recirced through the windings picking up heat and then pass through water cooled heat exchangers to give up the heat. The systems are built into the generator casings so unless you were part of the disassembly you would not know of the specifics. To use air the generators would have to be much larger to provide sufficient surface area to remove the heat generated by resistance in the windings (i.e. it is cheaper to build it this way). They have elaborate bearing seals, and no oxygen inside (nitrogen purged for maintenance or prior to filling for operation) to prevent combustion. So doggie-donuts yourself. JJ Having worked in a 1000 MW generating station, I can safely say this is doggie-donuts. I wouldn't have hydrogen (or any explosive gas) within 100ft of a high-power generator! Lloyd Sumpter James Johnson remove the "dot" from after sail in email address to reply |
Trailer Tires Overheating.
On Mon, 03 Nov 2003 00:20:28 GMT, Rick wrote:
Steven Shelikoff wrote: The wheel. The area of the wheel exposed to the gas is so small compared to the area of the tire producing the heat that I doubt it has much of any practical value in dissipation of heat above and beyond air flow over and radiation from the tire itself. I agree, the effect of using hydrogen would be minimal, but slightly larger than using nitrogen. My suggestion to use it was me being a wise a$$. JJ Though it doesn't apply much to boat trailer tires, the heat conductivity of the gas would work against tire cooling in the case of race cars and aircraft since it would serve to increase the rate of tire heating in heavy brake application. Many aircraft tire failures are due to overheated brakes, heating the wheels to the point of causing the tires to blow out or burn, not from heat generated by the tires themselves. Rick James Johnson remove the "dot" from after sail in email address to reply |
Trailer Tires Overheating.
Steven Shelikoff wrote:
Yeah, right.:) But not over and over Well, duh ... and if that does happen, i.e., stopping the plane with the remaining runway after an aborted takeoff, you're almost guaranteed a brake fire. Not true. But that was the point of my original statement, that the tires are more likely to be heated by the wheels and brakes than cooled by them. ... if a heavy gets up to takeoff speed on most runways, aborts and only has the brakes to stop it, chances are it's gonna go off the end of the runway. Not really apples to apples. RTO's at V1 are rare in any event and when they do occur it is likely because of a tire, or multiple tire failures so there is little braking available in any event. And I'm not sure where you get the idea that thrust reversers provide little braking at high speeds. They way they work, they really *only* provide braking at high speed and very little at low speed. They are the vast majority of braking at landing speed. They are aerodynamically most efficient at high speeds but they do not provide the majority of braking nor are they required to be used or even desired at all times. They cannot be used until the engine is at idle, there is weight on the wheels, they buckets have cycled open, and the engine spooled up again. By this time the autobraking has slowed the aircraft considerably. They must not be used below around 60 knots to prevent compressor stalls and sucking up garbage. They are useful only in a very narrow range, not at the highest speed where brakes are needed most or at the rollout when autobraking is off and manual braking is used. They are hard on engines and the modern design trend is toward no reversers, depending instead on carbon brakes. Rick |
Trailer Tires Overheating.
On Tue, 04 Nov 2003 17:00:12 GMT, Rick wrote:
Steven Shelikoff wrote: Yeah, right.:) But not over and over Well, duh ... and if that does happen, i.e., stopping the plane with the remaining runway after an aborted takeoff, you're almost guaranteed a brake fire. Not true. But that was the point of my original statement, that the tires are more likely to be heated by the wheels and brakes than cooled by them. ... if a heavy gets up to takeoff speed on most runways, aborts and only has the brakes to stop it, chances are it's gonna go off the end of the runway. Not really apples to apples. RTO's at V1 are rare in any event and when they do occur it is likely because of a tire, or multiple tire failures so there is little braking available in any event. And I'm not sure where you get the idea that thrust reversers provide little braking at high speeds. They way they work, they really *only* provide braking at high speed and very little at low speed. They are the vast majority of braking at landing speed. They are aerodynamically most efficient at high speeds but they do not provide the majority of braking nor are they required to be used or even They really only work well at high speeds, not low speeds. desired at all times. They cannot be used until the engine is at idle, They may not be used or desired at all times, only about 99% of the time. there is weight on the wheels, they buckets have cycled open, and the engine spooled up again. By this time the autobraking has slowed the aircraft considerably. They must not be used below around 60 knots to prevent compressor stalls and sucking up garbage. They are useful only in a very narrow range, not at the highest speed where brakes are needed most or at the rollout when autobraking is off and manual braking is used. They are hard on engines and the modern design trend is toward no reversers, depending instead on carbon brakes. None of that changes the fact that aircraft braking requirements and capabilites and tire heating have nothing to do with race car or boat trailer braking or tire heating. While it may be true for aircraft braking that the tire is more likely to be heated by the brakes then by the heat from tire friction, that's not true for most types of racing and especially NASCAR restrictor plate racing, when the brakes aren't even used but the tires still get very hot and might benefit from cooling through the wheel. Steve |
Trailer Tires Overheating.
Steven Shelikoff wrote:
None of that changes the fact that aircraft braking requirements and capabilites and tire heating have nothing to do with race car or boat trailer braking or tire heating. Never said it did, I just made the statement that tires are more likely to be heated than cooled by the wheels and brakes and used aircraft tires as a spectacular example. While it may be true for aircraft braking that the tire is more likely to be heated by the brakes then by the heat from tire friction, that's not true for most types of racing and especially NASCAR restrictor plate racing, when the brakes aren't even used but the tires still get very hot and might benefit from cooling through the wheel. I have absolutely no idea what "restrictor plate racing" is, what do you do, run with them? 8-) If the brakes are never used then the brakes won't add heat. Unless the area of the wheel exposed to the filling gas is a fair proportion of the area of the sidewalls then I can't see much heat going out the wheels regardless of the gas used. Are you sure there is a large area of wheel surface exposed anyway? I haven't seen a racing tire up close and personal but if they are like most other tires the bead/s run pretty close from side to side and it doesn't appear that there is much metal not covered by rubber in most wheels. Anyway, I don't buy the "runs cooler" argument for nitrogen any more than anyone should buy the "nitrogen expands less" nonsense. Rick |
Trailer Tires Overheating.
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If the brakes are never used then the brakes won't add heat. Unless the area of the wheel exposed to the filling gas is a fair proportion of the area of the sidewalls then I can't see much heat going out the wheels regardless of the gas used. Are you sure there is a large area of wheel surface exposed anyway? I haven't seen a racing tire up close and personal but if they are like most other tires the bead/s run pretty close from side to side and it doesn't appear that there is much metal not covered by rubber in most wheels. I have done a fair amount of measurements of tire temperature and heating using IR sensors in the wheel wells under racing conditions. The data was recorded with a data aquisition unit during racing, and downloaded to a laptop between races. We did 10 sample per second, with 1 degree resolution. I can state with confidence that a large portion of the tire cooling is due to airblast on the tire carcass. The percentage of cooling by the metal wheel is a very small fraction of the total heat dissipation. Going a step further, with certain high end racers, the inner safety liner completely insulates the metal wheel from the fill gas and tire face. This does not seem to affect the heat balance in any measureable way. Anyway, I don't buy the "runs cooler" argument for nitrogen any more than anyone should buy the "nitrogen expands less" nonsense. I am not sure what you have taken from this thread. Conventional wisdom is that the measured pressure increase is due to liquid water flashing to steam above the boiling point of water. It has nothing to do with the fraction of oxygen or nitrogen in the fill gas. In the turns NASCAR and F1 cars run peak tire temperatures between 225 and 250 degrees F. I leave it to you to offer an alternate explanation of the measured 4 to 16 PSI jump (nominal 30 PSI) under racing conditions. This increase is enough to completely scuttle chassis tuning. While you are at it, explain how switching from running "air" to dry nitrogen combined with a few forced purge-fill cycles eliminates the effect - the tires pressure changes pretty much as predicted by PV/T = PV/T. This stuff is not conjecture - it is measured data. If it does not match your expectations - perhaps it is time to reexamine your expectations. Mark Browne |
Trailer Tires Overheating.
Mark Browne wrote:
I am not sure what you have taken from this thread. Conventional wisdom is that the measured pressure increase is due to liquid water flashing to steam above the boiling point of water. It has nothing to do with the fraction of oxygen or nitrogen in the fill gas. I don't place much weight in "conventional wisdom" when it comes to physical phenomenon that follow well defined laws of physics. Water will not" flash to steam" at the pressures and temperatures you describe. In the turns NASCAR and F1 cars run peak tire temperatures between 225 and 250 degrees F. I leave it to you to offer an alternate explanation of the measured 4 to 16 PSI jump (nominal 30 PSI) If there was liquid water in the tire at the start of the race, at say 80 degrees F, all but the tiny amount required to saturate the filling gas would still be liquid. The filling gas will follow the gas laws. At 34 psig the gas temperature would have to reach approximately 280 degrees F to evaporate any liquid water in the tire. At 46 psig the gas temperature would have to reach approximately 290 degrees F to evaporate any liquid water in the tire. I have no idea what the tire volume is but if you do you can calculate the weight of water present in the filling gas as a saturated vapor at atmospheric pressure and temperature and if you know there is liquid water flying around in the tire you can calculate what temperature and pressure it takes for that liquid to change state. under racing conditions. This increase is enough to completely scuttle chassis tuning. While you are at it, explain how switching from running "air" to dry nitrogen combined with a few forced purge-fill cycles eliminates the effect - the tires pressure changes pretty much as predicted by PV/T = PV/T. IT looks like you are ignoring the vapor pressure of water and you probably do not calculate the partial pressure of the water vapor in the air filled tire. You are using the wrong gas law to begin with and when you get a dry tire with a dry gas the tire acts as predicted. This stuff is not conjecture - it is measured data. If it does not match your expectations - perhaps it is time to reexamine your expectations. I am only a simple mechanic, it is my place to follow the laws, not to change them. The gas laws are not predicated on anyone's "expectations" they are physical phenomena that scientists and engineers have used for a couple of hundred years with great reliability and repeatability. It appears that the only place they are held in abeyance is the race track. If I am missing something here I would really like to know what it is. It is an interesting subject. Rick |
Trailer Tires Overheating.
On Wed, 05 Nov 2003 02:20:32 GMT, Rick wrote:
Steven Shelikoff wrote: None of that changes the fact that aircraft braking requirements and capabilites and tire heating have nothing to do with race car or boat trailer braking or tire heating. Never said it did, I just made the statement that tires are more likely to be heated than cooled by the wheels and brakes and used aircraft tires as a spectacular example. And I'm just saying that while in racing, the brake rotors themselves can get extremely hot during braking, if there is so little heat taken away that the rotors alone are causing the wheels to be heated up to over 250 degrees then something's wrong with the setup. The same statement might not be true for an airplane, where the brakes are applied hard for only a short time and then they have hours to cool down. While it may be true for aircraft braking that the tire is more likely to be heated by the brakes then by the heat from tire friction, that's not true for most types of racing and especially NASCAR restrictor plate racing, when the brakes aren't even used but the tires still get very hot and might benefit from cooling through the wheel. I have absolutely no idea what "restrictor plate racing" is, what do you do, run with them? 8-) Uh, yeah. You run with them. They limit the horsepower available on the superspeedways to around half of what it normally available. That way, the cars never get going fast enough to have to use the brakes. If the brakes are never used then the brakes won't add heat. Unless the area of the wheel exposed to the filling gas is a fair proportion of the area of the sidewalls then I can't see much heat going out the wheels regardless of the gas used. Are you sure there is a large area of wheel surface exposed anyway? If there's not an inner liner, then yes, a large area is exposed. An inner liner is used for some races and not for others. As a quick and dirty example, Nascar wheels are 15" dia x 9.5" wide. The tires are 27.5" dia with a width of not more then 13.2". To make things easier, assume flat sidewalls, which will make the area calculation below come out on the low side. The sidewall area is around 2*(27.5-15)*pi = 78 sq in. Also ssume the wheel is a cylinder, which will also make the area calculation come out on the low side so it sorta cancels out. Also, assume that the bead takes up around 1/2" of the wheel width on each side even though it's a little less, so the area calculation of the wheel area will be a bit low. So the surface area of the metal inside the tire is around 15*8.5*pi = 400 sq in, or about 5 times the sidewall area. I haven't seen a racing tire up close and personal but if they are like most other tires the bead/s run pretty close from side to side and it doesn't appear that there is much metal not covered by rubber in most wheels. If you're using passenger cars as your example, you need to look at today's larger and wider wheels mounted with very low profile tires. They're closer to most racing wheel profiles. The area of the wheel inside the tire is significant. Anyway, I don't buy the "runs cooler" argument for nitrogen any more than anyone should buy the "nitrogen expands less" nonsense. I don't buy the "runs cooler" argument either. But I do buy the argument that you can control the amount of moisture in the gas easier if you're filling it with nitrogen then when plain compressed air. There's no reason I can see that extremely dry compressed air shouldn't work as good as nitrogen. But it may be cheaper and easier for the teams to buy a tank of compressed nitrogen then to dry compressed air to the same level of water content. Steve |
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