Quote:
Originally Posted by Kyleyadon
It was chilly and humid when I went to work the other day, so the car was covered in condensation. When I stopped for gas I looked at the way the airflow had affected the moisture on the car, and took some pictures with my cell phone. Sorry they're not very good, but it's a cheap phone that I only have because I need it for work. But what seems to be going on is that the airflow over the roof is about what you'd expect, until about three inches from the back glass, which is where the roof curves down to meet the back glass, at which point the moisture on the roof is completely undisturbed. The moisture on the back glass is likewise completely undisturbed. In fact it's not until you get to about the middle of the trunk lid that the moisture shows signs of airflow again. Which would seem to indicate that the airflow is detaching from the roof at the point where it begins to slope down towards the back glass and does not reattach until approximately the middle of the trunk lid. Which presents the question: Is it better to encourage the airflow to remain attached, such as with some VGs? Or is it better to encourage the airflow to remain detached by putting some sort of extension onto the roof so that the downward moving air misses the back of the car entirely?
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It depends.
Hucho suggests that for the optimum drag reduction,you'd convert the notchback to a Kammback.
However,there is evidence that it's not a one-size-fits-all solution.
Evidently,we'd have to consider each vehicle on a case-specific basis.And there's no apriori way to predict any specific outcome.Which sucks!