brucepick -
(not an aero-expert either, but I'll give it a shot)
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Originally Posted by brucepick
Aero-wizards,
I'm pretty sure the idea here is for the rear edge of spoiler to meet the template curve. Right?
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Yes.
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How about the slope of the spoiler, and it's front-to-rear dimension? Is any part of the spoiler that is forward of the template mostly inert, with little or no effect? Or is it helpful to extend it forward to or near the rear glass - that way very little air will flow into the cavity below the spoiler.
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My sense is that you have to tape the spoiler from front to back. See how the EV1 tapers from front to back in the top view? You *want* your car and spoiler to do the same. I think you want to get as close to the glass as possible. In my case, because I have a rear window wiper that would mean I would want to be as close as possible while still allowing for the wiper to be able to clean the rear window.
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Going past the template line would be bad, right? Tuft testing should show turbulence there??
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Yes. I think you want to do the prototype with the ability to adjust it forward and backward. The template gets you close and testing dials it in,
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And, how about sloping it downwards? I think on a "normal" spoiler, that would cause unwanted lift . BUT if the forward edge is at or near the glass, wouldn't a downward rear slope help the flow reattach more smoothly?
Thanks!!
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I am paranoid that the wind from the top and side of the car would get under the horizontal part of the spoiler, turn it into a parachute, and rip it off. I would make it so that it has a slight downward(*) angle. I would also protect the sides of the spoiler from wind getting in from the side. The sides of the Bonneville spoilers seem to accomplish this, whether by design or by chance.
[EDIT: (*) My brain is thinking that it has a downward slope from the point it meets the template.]
That thought process has led me to imagine this design for my wagon :
The green line is the flat spoiler.
It features side protection to protect against a parachute effect, a *slight* downward angle, clearance for the rear window wiper, extension only to the rear bumper line, and maintains about 80% rear visibility.
CarloSW2