Quote:
Originally Posted by California98Civic
Well, Pendragon, wonder no more, because I just tested it.  Drag and/or downforce added by the angle might just be what caused a decline in MPG. Across my 18 mile "course" at 16.5 throttle steady:
A (no mod): 51.7
B (mod): 50.4
A (no mod): 52.0
This was so dramatic a difference I could see it just a few miles after starting out. Slower speeds were another obvious indicator. Clearly, this design does not work, possibly for the reasons you suggest, though there are others here who might know more and might comment. But I will say that at 60mph it was difficult to keep the leading edge of the assembly taped flat onto the trunk lid surface. Even though it was just 2-3" behind the base of the rear window, it would separate and flap in the wind like a parachute. I taped it down hard with duct tape and started again. I should have tuft tested first. The air does not move the way I thought.
Next, I want to try a less aggressive approach, combining ideas you (Pendragon) and Brucepic and probably others have already suggested. That tiny "kamm" type add-on at the top of the window (for cleaner separation) and a small, flat spoiler that does not extend beyond the bumper and that is flat or slightly angled downward.
EDIT: Added previous long flat design photo, the over lay of both angles, and flat spoiler test results on the long flat spoiler, for reference: http://ecomodder.com/forum/showthrea...tml#post241134 |
California,does the fabrication in the thumbnail photo follow your red line,or fall off as in the photo?
Also,do you think the area on either side of the spoiler,between the end-plates and sides of car is in turbulence?
You may have created two longitudinal vortices above the tailights as the spoiler does not extend out to that region,and the downwash off the roof is not supported there with the existing voids.
I've never seen a rear spoiler which wasn't full width.It's hard to tell everything from photos.