Hello -
Back in this thread I was given feedback on what a proper Kamm-Back might look like for my car :
http://ecomodder.com/forum/showthrea...html#post41152 - Post #16
This led me to this design, which was deliberately limited in length by the distance to the back bumper :
I haven't done any serious work on this because I want to maintain rear-view visibilty, third brakelight visibility, the complexity of the gently curved roof shape, and the risk of a "parachute" effect if the top got loose.
Then I noticed this from the 1970's Pinto mods :
$11 worth of mods plus new tires - Car and Driver improves MPG by 25%
Quote:
Mod #3: Smoother tail (rear spoiler).
The aerodynamically ideal shape at the rear of a vehicle is a gradual taper that helps minimize the size of the turbulent wake left behind. But the slope of the Pinto’s rear window was too steep. By adding a six inch spoiler, they effectively changed the angle of air flow between the end of the roof and the back of the car. The result: a 7% MPG improvement.
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This made me wonder if I could compromise and create a simple flat spoiler that would emulate the endpoint of the kammback :
From an aero POV, do you think this would help? I am thinking that this is similar to Ernie Roger's new-Beetle
Wing Spoiler.
IMO the positives are easier construction, good rear visibility because only a "single flat line" of coroplast is in the way, third brakelight visibility, and (hopefully) less risk of a parachute effect. The only bad thing is that I would need to disable the rear-window wiper (one fuse), unless I made a gap between spoiler and the rear-window (Ernie did this for other reasons).
CarloSW2