7 replies to this topic

[MrAerodynamicist]

I'm reading a book at the moment on the aerodynamics of road vehicles.
Anyway. From my years of watching F1, my impressions has always been that the effect of the turbulance of following another car has always been to induce understeer on the following car. However, according to this book, the effect should be to induce oversteer due to a large chance in lift/downforce at the rear. Its only a page, and the data is gives is for road cars, but it does give a quick comment on winged single seaters where it again states oversteer.

Obviously the book is right, so am I just wrong in thinking that it leads to understeer in F1 cars or is there something in their aerodynamic design that changes the pattern to cause understeer?

One possibility I've considered is due to large amount of downforce due to ground-effects/diffuser. Now if this was less effected than wings then the rearward downforce would be less effected than frontal downforce ( relying solely on a front wing). Or am I talking >

[MrAerodynamicist]

I'll try and scan in the page, so you can see the graph etc

[BT52]

Well according to the drivers they experience understeer
And you would have thought they would know.

Or do they just experience understeer FIRST, then oversteer as they get closer?

[PDA]

Most road car aerodynamics are characterised by the amount of lift (particularly at the rear) rather than downforce. Race cars are different, and F1 cars suffer understeer when following closely. Even in NASCAR WC, they get understeer when following closely, and those body shapes are much closer to road cars than F1.

[MrAerodynamicist]

My initial thought was that it was a result of wings but it said that uindersteer for single seaters too. I'll try to scan it in tonight.

[Ali_G]

But think about it. There will be equal amounts of downforce taken of the front and rear wing yet the rear diffuser will be unaffected as the air under the car will be straightened out on the run under the flat bottom of the car.

Ali_G

[Wolf]

I'd say it should understeer, since the front wing will get in the turbulent flow first (thul loosing much downforce), but the body of the cat would, more or less, get the flow pretty much in shape before the rear diffusers; they should then loose considerably less downforce (because of better airflow). Hence, the car would have to be 'off balance', and understeering (the front wheels having less grip).
If the car was to oversteer than the turbulences should have more effect on rear diffusers than to front wings. Since I'm talking off top of my head, here's the thought. If rear diffusers, in normal circumstances, deflect the airflow so high as they do the smoke from the blown engine; than front wing of the following car would be much less affected by turbulences than the rear, and the car would oversteer (by the reason of greater downforce loss on diffusers).

[Downforce]

Not only is the flow turbulent for the following car (not really a big deal) but it is moving UPWARD and thus changing the effective AOA of the front wing on the following car.

Since the flow is not coming directly from in front of the car, but from below and in front, the front wing will make much less downforce because it has to 'turn' the air more to accomplish the same effect.

The turbulence is really not that big of a deal since the surface areas we are dealing with are relatively small. One GOOD thing about turbulent flow is that it stays attached longer than laminar flow and you get less drag as a result (albeit at a SLIGHTLY higher skin friction)