Ian P. wrote:There is also a Sauber site with good pictures of their rolling road which will go up to 150 mph and house a full size car. Most teams use 50% or 60% scale models for testing, cheaper and faster to fabricate parts.
As for simulating the heated air comming off the brakes, that is one for the CFD simulators. It would be near impossible to duplicate this in a tunnel.
These days, it's often marginally
more expensive to make parts for a wind tunnel model than a full-scale car. The parts on the full scale car are designed to be right on the margins in terms of their construction, so making a 60% scale copy can be a nightmare if the part is complex - the little aero signposts ('air this way, please') that cars are festooned with these days are particularly annoying because they have such delicate shapes. Something that is a carbon part on the car may be steel or alu on the model for ease of manufacture.
The reason teams use a scale model is accuracy. Although they like to put out publicity photos showing their full-size cars in the tunnel ("Look how big our shiny new tunnel is!"), that setup is hardly ever used for any kind of testing, because the cross section of the working area isn't big enough to accurately model the airflow in the space around and behind the car.
To make sure you get proper resolution of the behavior of the air not directly in contact with the car, you need a lot of space - too small in some dimension and it will fatally skew your results, as Honda discovered on the RA107. In CFD, the 'working section' simulated for a full size car is typically a 'box' of air something like 90ft high, 90ft wide and 300ft long. You can cut this down somewhat before it has any really major effects on accuracy - in CFD the mesh around the edges of the section has pretty big cells - but a full scale tunnel accurate enough for F1 would still have to be enormous, with subsequently massive demands for power and cooling. Even with the stratospheric budgets of modern F1, anything bigger than 60% is uneconomical to build.
Getting back to the original question, Ian is absolutely right, you use CFD for this kind of thing. It's far, far easier (and cheaper!) than anything you could come up with for a tunnel.
