Wind Displacement

[aaronoxf]

Hi guys, ive really enjoyed reading through numerous interesting topics that you have on this site, I have a question I hope you could help me with, I have had this going through my head for a while now, have asked in other forums but nobody can really give me a decent enough answer to prove me either right or wrong, I will happily be proved wrong if someone can provide evidence. so.....

As we all know a formula 1 car is pretty good aerodynamically, im guessing theres isnt much or very little wind displacement, like, for example in a car.

My question is....I was at Silverstone last year and noticed one of the drivers tear off one of his tear strips from his visor and throw it onto the track, this landed rather close to the racing line (maybe a metre or so off line). now it wasn't a very windy day and neither was it in danger of being hit by a car. This piece of plastic never moved even when the formula 1 cars came screaming past, my point is, was this because all of the air was perfectly routed through the car and no side ways wind displacement was evident? sure there is turblent air out of the back of the car, but nothing sideways. if you stood next to a formula 1 car with massive ear protectors and your eyes closed, would you feel it going past you (air wise)?

I have found a couple of photos that kind of state that the air is routed so well through the car that none, if very little, is displaced sideways.

Anyone help?

Sure the wheel are creating a slight problem


Here is a good example, everything looks very clean sideways

[hecti]

Well, a regular street car has a CD(coefficient of drag ) of about .3-.5
A formula one car has a CD of about 1 (of course it depends what track you are at, a track like monaco will mean increased drag because of the increase in downforce and in a track like monza, the decreased downforce will result in a lower CD). The higher the CD, the more drag an object produces, so to answer your question, a formula one car has lots of drag and thus displaces huge amounts of air (which results in the downforce needed to keep the cars on the track.)

I hope this helps

[roost89]

I think you mean, if you were standing beside an F1 car as it drove past, would you feel the wind off of it. If that's right.

I'd say yes. I'm not a maths or physics person, so can't work out how much is displaced or anything like that. However, in the previous seasons where bits have fallen off of cars, like the 'frisbees' that sat on the wheel. When a car drove past they were shifted away from the car and then sucked back in toward the rear as the pressure dropped from the diffuser and rear wing pushing air upward into the sky.

Unfortunately, no videos exist of this as they get taken off youtube before you've had time to notice it's been uploaded and watched it

As regard the visor strip. I'm not sure how that wasn't moved. Maybe it was stuck to the track I'm surprised it didn't move.

Sorry I can't help more.

[Belatti]

I guess the "wind chaos" of F1 cars happen it all rearwards. The Brawn GP pic you aaronoxf posted probe that. You can notice when a massive engine failure occurs, too.

And -again- I guess thats because every "drop" of air that can goes to both sides of the car body is meticulously driven to the aero parts (DDD, Wings, etc) of the car.

[xpensive]

I think it was because a tear-off sticks to the ground, just like the plastic-foil you have a home.

[aaronoxf]

yeh part of my thinking was that it might of just stuck to the floor but other parts of my brain were thinking that if the air is so well fed through the car to the aero parts then how can there be any wasted air/wind displacement? of course the air coming out of the back of an f1 car is another story

[speedsense]

yeh part of my thinking was that it might of just stuck to the floor but other parts of my brain were thinking that if the air is so well fed through the car to the aero parts then how can there be any wasted air/wind displacement? of course the air coming out of the back of an f1 car is another story

The CFD image you have may have not included wakes away from a certain distance of the body, for reasons of visually seeing the air flow over the car. External wakes would clutter the view as they "grow".
The one thing that can't be redesigned aero wise are the tires. Controlling what is before it and after it is possible with the rules as limitations. Wings, side pods create lateral wakes.
The best designed, slippery boat hull will still leave a wake from the leading most edge of the hull and that wake will expand outward (laterally).
The same is true on an F1 car. When a car gains the draft of the one in front of it, passes the car but remains very close to it (within millimeters) it is still drafting the front car due to the wake, until it reaches half way of the front car and the wake is no longer big enough for the following car to fit into it.
If the drafting car were to stay close the original car that was it passing, when the passed car reaches the wake (half way approx) it would then start drafting the car that passed him.

The next time it rains, pay attention to how much water is sprayed to the side and you'll see what I mean, especially from the tires (part of this will be because the rain tires work partly as a water pump, by tread design)