10 replies to this topic

[b3nster]

Just curious, on long straightaways, I often see mist forming and sort of 'waving' off the sides of the tail wing of the cars. I assume this is some sort of condensation, but can anyone give a better explanation? I'm curious.

[PDA]

The change in air pressure causes the water vapour in the air to condense and appear as a cloud. Similar to the "con" trails on high flying aircraft.

[mhferrari]

Contrails, sometimes you will also see them on the wings of fighter planes.

[A3]

Actually, it's the car reaching the speed of sound....Just like this F-18:;)

[MrAerodynamicist]

Its a worm hole, its a worm hole!

[Yelnats]

A3, That is the most fantastic picture I've seen of that effect since I saw the overhead shot of the shock wave coming off the British Land Speed record car. Great stuff!

Is that a cloud of sweat around the pilot's head?;)

[Yelnats]

Actually a jets contrail is produced in an entirely different way and is generated by the water vapor condensing from the jets exhaust. WW2 dog fights over London produced the same effects and the Londoners became experts at telling which type of plane generated which trail.

The contrail produced by an F1 car (and the jet shown above) is produced by the lowering of the air preasure around the rapidly moving object causeing the relative humidity to momentaritly exceed 100% and condense thus causeing a momentary fog which dissapates as soon as the preasure returns to normal. The higher the humidity the greater the trail.

Comparing contrails between two race cars on a given straight during a race is a good way to tell which car is running the most wing as the greater angled wing produces a bigger preasure drop and a bigger contrail.

[f1pro]

I think that it could be a sort of vortex called "toubillons marginaux" in french(i dont know it in english,sorry) cause by the different directions of the air travelling under and over the wing. This can be easily see at the end of an airplane wing. In this type of vortex, the water is condensing(dont know why)

[FucF1]

If you want to see a movie of it check out the Test Mk2 thread in readers comments, I posted a link to a cool video on the last page.

[Wolf]

We had similar type of thread soewhere in recent past (I could swear it was on RC, but dunno what it was doing there:)), so I'll basically say what I said there. The thing is quite simple- the maximum content of vapout in the air decreases wit both pressure and temperature (pressure being relevant issue here). So on the upper side of aerofoil (in case of F1, down sidee in case of aeroplanes) where is significant increse in pressure maximum amount of vapour (which can mix with dry air) decreases and thus the most of the vapour from the air, which is in the air at normal conditions, is forced to condensate. As simple as that (I hope I explained it good, but I doubt that:)).

[Yelnats]

Perhaps I can expand on Wolf's explaination.

The word CONTRAIL is a contaction of CONdensation TRAIL and is produced on and F1 car by the turbulence around the ends of the wings. The turbulence there is at it's maximum as the high pressure air on the top of the wing makes its way around to the low pressure area on the bottom.

This produces an intense vortex behing the wing tip which takes the form of in a rapidly spinning tube of air trailing the tip. Centrifugal forces produced by this spinning mass of air result in a low pressure area in the center which instantly lowers the temperature of this air to below the dew point. The contrail is the visible evidence of this and the higher the humidity, the lower speed that it becomes evident.