Quote:
Originally Posted by Daox
I'd have to disagree, I don't think its debatable. 
#1) They increase frontal area which inherantly increases drag.
#2) There is no way they don't cause separation. Its an edge hanging out from the car a good inch. Without it, there is at least has a chance for the flow to stay attached. |
And hence the debate
1)I am not arguing that they don't increase frontal area
2)I am not arguing that they don't cause separation... rather that they COULD keep air flow attached to the point that it's parallel with the car instead of it separating at an angle away from the car. IN THEORY this COULD reduce the Cd of the car. If they are completely contained in a region of separation they will have little or no effect. The only way they hurt the car's Cd would be if there is really no region of separation.
This being said, I would guess that if you were able to do coast down testing the Cd would not vary enough for you to notice.