Miguel wrote:Are you trying to tell me that the equation of state of Air (70% nitrogen) deviates considerably from nitrogen?
Well, I don't know what you call "considerably", but, as usual, you all know my preferred style (long posts with lots of back of the envelope numbers, long live F1Technical!).
Miguel is right about the gas equation. However, remember this, Miguel (btw, with all due respect, are you starting to forget the basics? Too many nuclear equations, I guess...):
The volume of a gas at a constant pressure is directly proportional to the temperature of the gas within its gaseous range
That's perfectly understandable. If you try to measure the pressure of Nitrogen at, let's say, 50 Kelvin, it's zero, because the thing is solid
What does that mean? It means that any element that becomes a gas at temperatures below 90.2 Kelvin (the temperature at which oxygen becomes a gas) has a different rate of increase in pressure for an increase in temperature. Let's assume we have a temperature range of 300 to 350 Kelvin inside
the tyre, to check the "pressure factor" of both elements.
Yes, yes, I know half of you have thrown your hands in despair after the previous paragraph. However, if I'm not mistaken (and I'm never wrong!).
Oxygen becomes a gas at 90.2K (Kelvin), increasing in volume (or increasing in pressure within a fixed volume for the temperature range mentioned) by a factor of .209, Nitrogen becomes a gas at 77.36K, increasing by a factor of .199.
So, my trusty calculator tells me that there is a difference of 0.01 in 0.209 (5 percent, give or take) of difference in pressure increase when you use nitrogen. As you start with 80% of nitrogen when you use regular air, you "affect" only 20% of 5 percent when you replace air by nitrogen.
In the end, my back of the envelope calculation tells me that you get a 1 percent difference in spring rate for an increase in temperature within the range I mentioned.
Big deal. Considerably? I don't know, but F1 is called the piranha club: any advantage, even if it's a placebo
However, I have two questions:
First: if the above is true (I repeat, as the mexicans say: I'm never wrong ... and when I'm wrong, I'm enchanting!) why don't they use helium
? Helium becomes a gas at 4.22K (the lowest temperature for gas conversion of all elements), which gives me a pressure increasing factor of .158. Please, pass this clue to Williams, not to Ferrari or McLaren...
Second: how do they fill the tyres?
Shouldn't the tyres require a complete vacuum before being filled? How do you get rid of the air inside, before filling with nitrogen? Damn, engineering is always full of "contaminants" that scientists don't take in account...
So, my answer is: yes, as spring rate variability goes, nitrogen is superior to oxygen and helium is superior to both
. The differences are in the range of a few percent points. I won't go into helium buoyancy and less un-suspended mass, this is for another "stratospheric" thread... and we already had it, including the rotational energy of the lighter gas. We are nuts for racing, don't we?
However, if any entrepreneur is reading this, I have an idea: How about selling Bridgestone Tyres balloons
at the entrance of GPs... filled with helium, of course (we should use another name to avoid lawsuits, like "Bridgeclone" or something). That
would be funny, and I bet they would sell like hotcakes. Following that, we could sell also Max Mosley Balloons, inflated with hot air.