2 replies to this topic

[NRoshier]

I know the old (i.e. before COT) cars used a relatively simple spoiler that was trimmed to suit the needs of the day.
I also assume that these worked in reducing rear lift by creating a higher pressure (than would normally be the case sans spoiler) over the rear of the car and thus tripped or promoted the seperation of the surface layer at say the top of the rear window. This seperation means that the lift that would otherwise occur does not. So less rear lift means more traction and stability. I have also heard that there is a reduction in drag...yet would htere not be a greater wake?...I am obviously missing something.
Part two: the spoiler would obviously create a greater neg pressure at the rear of the car. Were diffusers/ground effects legal, would this not be advantageous in another way in that the greater neg pressure could act as a minor 'driver' for the diffuser and the great pos pressure on the top assist downforce too?

[exFSAE]

The spoiler will indeed change the pressure acting on the top of the car, to reduce lift. I believe there are time when you can put a spoiler on a vehicle that for one reason or another makes the car wake a little less violent and reduce the net drag, but I would highly doubt this to be the case on the old car. I'd say it would increase it.

I doubt the airflow change at the top of the rear deck of the car would have much or any significant effect on the flow rate at the bottom of the car.

[GeorgeTheCar]

I believe that the purpose of the "spoiler" is to generate a more significant vortex at the rear of the car to pull air out from under the car, going back to the days of the small chin spoiler on the Corvair which served to limit the amount of air under the car, doing much more for downforce than the spoiler at the rear.

IN the COT the balance has changed because of the much more effective splitter (plate) on the front of the car and the rear wing is a control or balance item, probably designed by NASCAR to limit total downforce.

I love the way the NASCAR "experts" talk about "taking the air off the spoiler" when the real impact and explanation of drafting is the removal of the vortex being shed off the rear of the car.