Quote:
Originally Posted by aerohead
laack,please go to Search Ecomodder and key in 'Aerodynamic Streamlining Template Part-C and look at the second image posted there.Then consider scaling a side-view image of the Civic to fit in under the template as it is specified for use.
The curve will demonstrate a reasonable path the air would follow without separation.
You could fashion a foil for the back of the roof and also a upswept spoiler or straight back foil which pushes the Civic's body form closer to that of the template curve.
I believe that the airflow on top of your trunklid is not 'clean' enough to allow VGs to operate.
The upswept spoiler will force air to re-attach and it should lower the base pressure behind the Civic for an overall drag reduction.
You can see from the template that the air likes long,gently tapering aft-bodies.If you'll stay close to this form you'll see an improvement at the pump.
P.S. If your bound and determined to play around with VGs,you'll want them on the roof ahead of the drop off for the backlight.Check out the Mitsubishi R&D for their Lancer.For these things to work,they must be carefully scaled and placed.
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I ran some quick numbers just to see what my options might be.
- if i try to match the template, I would need to extend my tail end about 19 inches. I'm sure someone around here would rip that off to tighten up their parallel park job.. cant do it.
- If i extend it just 10" it would be 12 degrees slope, as previously recommended, from trailing edge to leading edge of rear windshield.
- the glass slope down is 22 degrees
- slope from leading edge of glass to trailing end of trunk is 14 degrees
disclaimer- this assumes that all my measurements and calculations were accurate. inconsistent measurements forced me to take an average of height and length from top of glass to point equal to top of trunk then from that point to the end of the trunk.
random thoughts/options at this point- I remember an older thread on here posting VG results including a youtube link. promising tuft testing but disappointing results. no change in mpg. rough experiment but not enticing enough for me to waste my time on that alone.
extend a piece coroplast back 11 inches-I'm not fully convinced that that will actually reduce my wake or smooth the transition of separated airflow at all. This plus VGs. out of curiosities sake i may do it just for the tuft test a couple of coast down tests.
attach an up-swept spoiler- in terms of drag reduction it seems counter productive but i do understand that it makes the air's path a little longer & gentler. I'm not willing to rule it out yet, but is there any data associated with how much improvement it can yield.
Any other thoughts?
later plans are grille block and rear wheel covers. rust is an issue on the rear wheel covers though so i'm still trying to figure out how to attach it w/o drilling into visible portions of the bumper. I also want to hook up an led to the rad. fan so i know when its on.