On planes they use things like that when a curve is too sharp and to redirect the laminar flow so it stays connected. But that looks more than a bit extreme. Something like that above the rear window of a civic sedan would probably work to keep the flow connected. I think mitsu used one on the evo too. I think on planes they use them between 12 and 25 degrees of variance from the flow. I was going to try one on my short-lived civic 2 door.
I'm going from memory and I haven't read anything about it for 3 months. I bet our resident HPV builder knows the real answer.
Where are ya trebuchet, chime in here.
"If you want to save gas I suggest you permanently remove the drivers seat and steering wheel. That seems to help." -Oscar Halverson
I agree with Erik, the main purpose of those deflectors is to deflect air downwards to help keep the rear window clean. In the process of doing so, they create lift and probably more drag than a small downforce-generating spoiler. Whether or not they'd actually help simulate laminar flow is anyone's guess. IMO, VGs would be a more passive approach to attaining the same goal.
__________________ 1993 Volvo 240 Wagon - 323k miles (awaiting recommissioning) 1999 Audi A6 Avant Quattro - 149k miles(the NEW daily driver)
that thing looks a bit to dramatic to give me the idea that it would help, but a test is the only way to be sure.... perhaps something similar to that would help it it was placed behind the hatch rather than scooping around it, so that it wouldn't add any frontal area... but than again most hatchback i've seen that seem to be geared towards economy use as straigt lip that continues the lines of the roof... sometimes it angles slightly upwards... although that might be for downforce and stability.
filling in the wake is not always a good thing... you want the wake to be shaped like a small cone, but you don't want the air to go over a steep edge so that it creates a swirl that sucks at the back of the car... that's why most cars have a sharp trailing edge and some cars wich seem to slope down all the way, like a VW beetle or some older porches have not so good drag quoefficients and benefit from big spoilers that sit in place of the average sedans trunk.