Quote:
Originally Posted by Fat Charlie
Even with detached airflow, wouldn't there still be a real benefit to filling in the wake? It wouldn't be optimal, but it looks a lot cleaner than simply leaving a large square hanging out back there to hold you back. I'd expect that "slightly detached" airflow would be a whole lot better than "completely abandoned" airflow. I'm thinking along the lines of "anything that brings you closer to the template helps" with the spoilers.
I'm actually asking a question here (not putting forth an argument)- I'm ignorant enough that I only have aerodynamic questions, not opinions.
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It would seem logical that filling in the wake would help, and I would normally agree, but if you make the angle wrong, it hurts. With between 10 and 15 degrees being the "optimal" for low drag, between maybe 20 and 30 degrees makes things worse (with 30 degrees adding a LOT of drag AND lift). After 30 degrees, you go back to having the wind not care, and it's like having a 0 degree back end (thought there is still added lift up to about 60 degrees). I guess what I am saying is, if done incorrectly, you can make things worse. From looking at the pictures of the van, they don't look to have done anything bad, just that it could have been done better. They didn't see much aero-improvement with the extension, and that should have been an indicator. I am guessing that if the corrected the extension to maintain attached flow, the benefit would be noticeable. (This is my aerodynamic opinion, since I can't actually test it.)