mricorp said:If anyone is interested I have an AC Schnitzer version that I am selling. It is already painted LeMans Blue but I have never installed it and still have the complete installation materials.
I changed my mind on putting it on.
Whoa! I was talking about the 3.0 CSL type of roof spoiler that creates a channel that traps the boundary layer along with a good chunk of freestream airflow as the one having some merit. These little E39 eyebrow things are highly suspect to me...I would have to see some surface pressure data to believe they aren't detrimental.BmwNut said:Chuck is right, there is some merit to them.
Wow - thanks for the detailed analysis! :thumbsup:HBRAMSTEDT said:Regarding aerodynamics the roof spoiler would increase drag. It may clean up the boundary layer on the roof top and actually delay detachment of the flow a bit. However, it will reduce the base fill behind the rear window and rear body near the license plate. You will have a much lower pressure area behind the car resisting forward motion. The slope of the rear roof area and the angle of the rear window are designed to encourage a somewhat controlled filling of the dead water region behind the car including behind the rear window. The roof spoiler will create an increase in drag without doubt. I have read about vehicle aero. for a long time and studied it at high speed on the public highways at night. The SAE has numerous publications on the evolution of vehicle aero. that are quite good. Roof spoiler = bad aero.