Brazilian GP 2010 - Interlagos

[sknguy]

I've not heard any of the teams mention it, but does air quality effect the performance or reliability of engines? Such as sand particles at Bahrain, other airborne chemicals at urban circuits, the higher levels of oxygen that may be present at circuits like Spa or Hockenheim? Are these things ever a concern for either the performance or reliability of their equipment?

Hmm... I was thinking that this might actually be a question for the technical threads. But another question would be: does airborne particulate matter effect aero, or tire performance too?

[PlatinumZealot]

Water vapour makes the air thinner and air resistance goes down since water is a smaller particle than your typical air components O2,N3, Co2 etc.
Dust as you know can affect the engine's air filter.

[hollus]

A gas molecule's volume has little to do with its effects on the car. The volume occupied by gases depends mostly on the kinetic energy of the molecules. It's mass, yes, mass is important, mass is what pushes the car creating downforce and drag, and water is a bit lighter than O2 or N2.
More important though is that H2O dilutes the air. If you add 1% of H2O (which the engine can also not burn) to the air, since the density stays constant (assuming altitude and temperatureconsitions stay the same all above you in the air column), you are diluting the O2 content by 1%, like in from 21% to 20.79%.

[Gerhard Berger]

Early weather predictions: Clear and sunny on Saturday, changeable conditions on Sunday (i.e. chance of rain).

[raymondu999]

Question. How does the air pressure etc that has been discussed affect the power disparity? Say if the Renault was slightly down on power (I'm not saying it's the 40bhp that Horner is talkinga bout, just saying it might be) would it decrease or increase the disparity?

[SiLo]

What I don't understand is how they claim they lose power, when they are shoving in as much as possible into the engine anyway. The air in the airbox will get sucked in a compressed as it reaches the engine.

[Sean H]

What I don't understand is how they claim they lose power, when they are shoving in as much as possible into the engine anyway. The air in the airbox will get sucked in a compressed as it reaches the engine.

The amount of air is the same. The oxygen is less in the higher altitude air, thus, less power.

[andrew]

Johnny Herbet has been announced as the guest race steward for the 3rd time this year.

[hollus]

The amount of air is less in altitude, less molecules per unit of volume (less pressure in pV=nRT). The composition (percentage of oxygen) stays about the same regardless of the altitude (within limits).
The engine can breath 8% less molecules or air than at ground level, hence 8% less molecules of oxygen to burn and about 8% less power. I don't know how much they can compress the air in the engine intake, but if that is the same for all teams, all will lose about 8% of power. The cylinder volume is fixed, the max RPM is fixed, and hence at max air intake, the engine will take in 8% less oxygen and have 8% less power.
Of course, engine power is not everything, and the car will also find 8% less air in its way. Hence they will experiment less drag and top speed might not be affected or it might actually increase (Xpensive, drag varies roughly with the square of the speed, right? How does it change with air density?). And with 8% less air to push (and pull) around, downforce will also get reduced. By how much? I believe that is anybodies' guess as the air will also be pushed to different places that it would be at sea level.

[Sean H]

yes, I worded that incorrectly, thats what I get for posting from my phone while should be working!

[Miguel]

Of course, engine power is not everything, and the car will also find 8% less air in its way. Hence they will experiment less drag and top speed might not be affected or it might actually increase (Xpensive, drag varies roughly with the square of the speed, right? How does it change with air density?). And with 8% less air to push (and pull) around, downforce will also get reduced. By how much? I believe that is anybodies' guess as the air will also be pushed to different places that it would be at sea level.

I'm not xpensive (not meaning that I'm cheap, either!), but at the speeds the F1 cars move, you can assume both lift and drag are a linear function of the air density and a square function of speed. Of course, both Cd and Cl change with speed, but those changes are considerably smaller in the range of speeds we're moving (i.e. nowhere near Mach 1)

[Gerhard Berger]

Just to settle the engine debate, this is what Renault's Remi Taffin had to say on the matter:

Running at altitude costs an F1 engine around 8% of its power. Despite losing this power, the altitude actually has a positive impact on the engine because the moving parts suffer less. There is less air entering the engine which means less pressure and less strain on the pistons, conrods, crankshaft and every moving part.

[Richard]

It is not "despite" losing engine power, it should "because" of losing engine power.

Less power = lower forces = longer engine life

[ringo]

Everyone has their theory. We've seen differing opinions; and they may well be right. I guess this has to do with how they expect to run the engines. I'm no F1 engineer so i can't argue with the Renault guy.

Less power = lower forces = longer engine life

the other side of the coin; which is generally quite true but doesn't seem to be a concern:

equal power = more engine speed = higher forces = shorter engine life

We should take note of this as well, as it relates to the power loss and load:

The engine engineers will also work hard over the weekend to deliver engine mapping that provides good torque delivery, especially at low revs.

“There are a couple of tricky low-speed corners so the engine needs to be drivable at the lower end of the rev range from 8,000 to 13,000 rpm,

[Arunas]

the other side of the coin; which is generally quite true but doesn't seem to be a concern:

equal power = more engine speed = higher forces = shorter engine life

Can't understand, how more engine speed can be used? Are these not limited to 18k rpm?