helium in tires?
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From: sarasota, fl
helium in tires?
an old school figure8 track racer i met told me they used to fill their tires with helium instead of air because it was lighter and therefore made less weight/rotatiing mass?
was this guy off his rocker, or is that for real?
was this guy off his rocker, or is that for real?
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From: sarasota, fl
Originally posted by Brady_96Z
Helium is expensive and it's a very small molecule, it will leak out where air won't. You could spend money better elsewhere.
Helium is expensive and it's a very small molecule, it will leak out where air won't. You could spend money better elsewhere.
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From: In a house by the bay
Air is about 80% nitrogen and some 20% oxygen with helium and other stuff making up a very small percentage.
Now, if you look at the atomic weights of helium vs nitrogen alone, you'll see that your friend is right. By my numbers, 1 liter of nitrogen (I'm simplifying without adding in the oxygen) weighs ~1.25 grams vs helium at ~.179 grams per liter. That's a factor of ~7.
I'd guess that there is a slight weight savings but probably not anything substantial. I know they use to use nitrogen in aircraft tires for the same reason.... weight reduction.
-Mindgame
Now, if you look at the atomic weights of helium vs nitrogen alone, you'll see that your friend is right. By my numbers, 1 liter of nitrogen (I'm simplifying without adding in the oxygen) weighs ~1.25 grams vs helium at ~.179 grams per liter. That's a factor of ~7.
I'd guess that there is a slight weight savings but probably not anything substantial. I know they use to use nitrogen in aircraft tires for the same reason.... weight reduction.
-Mindgame
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From: Clovis, NM
There is a 4X4 truck guy in my shop that use to do it to his trucks so they could go through mud better and hydroplane over water so he said.
And I have also herd that dragsters do it to, they say it is lighter, it doesn't expand as much as air.
If you wanted you could just use Argon, it is cheaper and all most as light with the other same trates.
And I have also herd that dragsters do it to, they say it is lighter, it doesn't expand as much as air.
If you wanted you could just use Argon, it is cheaper and all most as light with the other same trates.
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From: Upstate NY
Originally posted by Mindgame
I'd guess that there is a slight weight savings but probably not anything substantial. I know they use to use nitrogen in aircraft tires for the same reason.... weight reduction.
-Mindgame
I'd guess that there is a slight weight savings but probably not anything substantial. I know they use to use nitrogen in aircraft tires for the same reason.... weight reduction.
-Mindgame
Weight isn't really the reason Nitrogen is used, IMO. I agree that helium leaks out easily because the molecules are so tiny.
FWIW, a jet fighter may have 200 psi main gear tire pressure and if it's carrier based, nearly 300 psi. A 30,000 lb fighter crashes onto a carrier deck at nearly 150 mph on two 14 inch tires not much larger than a typical car tire...but one hellofa lot stronger.
Thought experiment: When you accelerate hard, does the air "slosh" around in the tires and throw them out of balance?
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From: 51°N 114°W, 3500' elevation
Originally posted by OldSStroker
Thought experiment: When you accelerate hard, does the air "slosh" around in the tires and throw them out of balance?
Thought experiment: When you accelerate hard, does the air "slosh" around in the tires and throw them out of balance?
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From: Cortland NY
Originally posted by Stephen 87 IROC
If you're travelling at the speed of light following someone else who's also going at the speed of light and you flash your headlights to pass will they see them? Will you see the red and blue police lights in your mirror when they stop you from speeding?
If you're travelling at the speed of light following someone else who's also going at the speed of light and you flash your headlights to pass will they see them? Will you see the red and blue police lights in your mirror when they stop you from speeding?
My highschool math teacher spent an afternoon working out that problem and came up with no.
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Originally posted by Stephen 87 IROC
If you're travelling at the speed of light following someone else who's also going at the speed of light and you flash your headlights to pass will they see them? Will you see the red and blue police lights in your mirror when they stop you from speeding?
If you're travelling at the speed of light following someone else who's also going at the speed of light and you flash your headlights to pass will they see them? Will you see the red and blue police lights in your mirror when they stop you from speeding?
This was explained to me by someone with a PhD in physics, but I forgot the full explanation.
Last edited by Socrates; May 30, 2004 at 06:24 AM.
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From: Upstate NY
Originally posted by Stephen 87 IROC
If you're travelling at the speed of light following someone else who's also going at the speed of light and you flash your headlights to pass will they see them? Will you see the red and blue police lights in your mirror when they stop you from speeding?
If you're travelling at the speed of light following someone else who's also going at the speed of light and you flash your headlights to pass will they see them? Will you see the red and blue police lights in your mirror when they stop you from speeding?
If you could see the cop lights, would they be red or blue shifted? BTW, how did the cop catch up to you? Maybe thru a worm hole?
What's the penalty for breaking the speed of light law?
Why not hydrogen in the "tars" instead of helium. It's much lighter.
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Originally posted by Socrates
If you’re traveling at the speed of light and the guy behind you also traveling at the speed of light flashed you, you will indeed see him flashing you... The speed of light is the only true physical universal constant.
If you’re traveling at the speed of light and the guy behind you also traveling at the speed of light flashed you, you will indeed see him flashing you... The speed of light is the only true physical universal constant.
Actually, you wont see him flash you because in order for you to SEE his headlights, the light from them would have to travel FASTER than the speed of light.
Also, the speed of light isn't constant. It depends on the medium it's passing through.
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From: In a house by the bay
Originally posted by OldSStroker
Dry nitrogen doesn't freeze at -70F, the temp at jet cruising altitudes. Air generally has water vapor in it which freezes at high altitude and boils if the tires get hot during a hard stop. Neither situation is confidence-inspiring to the pilot. Water vapor in air screws with pressure on race tires which regularly get the rubber above 212F. N2 is used here, too.
Weight isn't really the reason Nitrogen is used, IMO. I agree that helium leaks out easily because the molecules are so tiny.
FWIW, a jet fighter may have 200 psi main gear tire pressure and if it's carrier based, nearly 300 psi. A 30,000 lb fighter crashes onto a carrier deck at nearly 150 mph on two 14 inch tires not much larger than a typical car tire...but one hellofa lot stronger.
Thought experiment: When you accelerate hard, does the air "slosh" around in the tires and throw them out of balance?
Dry nitrogen doesn't freeze at -70F, the temp at jet cruising altitudes. Air generally has water vapor in it which freezes at high altitude and boils if the tires get hot during a hard stop. Neither situation is confidence-inspiring to the pilot. Water vapor in air screws with pressure on race tires which regularly get the rubber above 212F. N2 is used here, too.
Weight isn't really the reason Nitrogen is used, IMO. I agree that helium leaks out easily because the molecules are so tiny.
FWIW, a jet fighter may have 200 psi main gear tire pressure and if it's carrier based, nearly 300 psi. A 30,000 lb fighter crashes onto a carrier deck at nearly 150 mph on two 14 inch tires not much larger than a typical car tire...but one hellofa lot stronger.
Thought experiment: When you accelerate hard, does the air "slosh" around in the tires and throw them out of balance?
But wait, there's more! (yeah, I watched an infomercial a few minutes ago
)Dug this up on NASA Aeroquiz...
Q: According to U.S. Federal Aviation Regulations (Part 25.733e, to be exact), any tires mounted on braked wheels for airplanes heavier than 75,000 pounds must be inflated with dry nitrogen or other gases shown to be "inert." What's wrong with using ordinary air?
A: Well, the phrase "inert" gas says it all. When you see the pictures of the white-hot brakes at the rejected takeoff test, when you know that the tires are made of rubber and so could burn, when you know that the tires will let go their gas content in the process, as a cooling measure, you sure prefer to have them inflated with something that will not promote fire at all.
Although they are rare and used only during emergency landings, maximum effort stops can result in very hot brakes. It is not impossible for grease, oil, or the tires to smolder on such a landing, and the last thing anyone would want would be air from a burst tire to feed the fire.
Interestingly, engineers design thermosensitive fusible plugs to be used near the wheel spit that safely vent the tire pressure if the local temperature reaches a predetermined level.
As stated in the regulations, the gas used to inflate the tires must be dry, since ambient temperatures at cruising altitudes are very cold. A chunk of ice, even a small one, inside a tire can throw the wheel off balance during landing. Carbon dioxide, for this reason, is also a poor choice for an inflation gas.
Dry nitrogen is desirable for other reasons as well. It does not promote rust and it will not oxidize the rubber compounds inside the tire.
Contrary to many responses to this week's question, nitrogen offers no real weight advantage over ordinary air. The difference in weight between an air-filled tire and a nitrogen-filled tire is very small!
- The Aeroquiz Editor
A: Well, the phrase "inert" gas says it all. When you see the pictures of the white-hot brakes at the rejected takeoff test, when you know that the tires are made of rubber and so could burn, when you know that the tires will let go their gas content in the process, as a cooling measure, you sure prefer to have them inflated with something that will not promote fire at all.
Although they are rare and used only during emergency landings, maximum effort stops can result in very hot brakes. It is not impossible for grease, oil, or the tires to smolder on such a landing, and the last thing anyone would want would be air from a burst tire to feed the fire.
Interestingly, engineers design thermosensitive fusible plugs to be used near the wheel spit that safely vent the tire pressure if the local temperature reaches a predetermined level.
As stated in the regulations, the gas used to inflate the tires must be dry, since ambient temperatures at cruising altitudes are very cold. A chunk of ice, even a small one, inside a tire can throw the wheel off balance during landing. Carbon dioxide, for this reason, is also a poor choice for an inflation gas.
Dry nitrogen is desirable for other reasons as well. It does not promote rust and it will not oxidize the rubber compounds inside the tire.
Contrary to many responses to this week's question, nitrogen offers no real weight advantage over ordinary air. The difference in weight between an air-filled tire and a nitrogen-filled tire is very small!
- The Aeroquiz Editor
Interesting.
-Mindgame