I'd like to ask all of you here about what kind of drag penalty that results from using a spoiler ( or trunk lid ) to reattach airflow on a car with a rear taper that is not the ideal angle.
Note that the Camaro had a worse Cd
without that spoiler, even though it kicks up at an angle ( The same results can be found in
upward tilting spoilers on the R&T project cars - the Crisis Fighter Pinto and Crisis Fighter Datsun Z car.
On cars such as this Fusion, if you follow the roof line out at a 15 degree angle, you eventually meet up with the edge of the deck lid spoiler. I am guessing that this acts as a way of grabbing the airflow and bringing it back into the ideal trajectory.
For those folks on this site not willing to create a huge boat tail on the end of their prized car, why not create a large shelf spoiler that is easily removed ?
From the examples above, it seems as though adding a spoiler can sometimes have a drastic reduction in drag.... but what are the penalties ?
Thanks !