Cobalt Coupe Aero Mods

[OKXXFE]

Originally Posted by aerohead

* Also,it would lower the stagnation point which is very good for low drag and lift.Ideally,the nose would be vertical,or slightly canted backwards with the air dam integrated right into it.Just like NASCAR.You'd need to watch your approach angle clearance (16-degrees) so it doesn't scrub or worse.
*The rear backlight area is where the money is.The current 2nd-gen Insight has a fine contour to mimic.If you get the roofline up to 'Kamm' specs,then she's a candidate for tail,which should get you into 50-mpg territory.Easy.

For the nose bit, how do you mean vertical or canted backwards? I am picturing the opening at the lowest point being perpendicular or slightly negative angle respective of the horizontal. I mean with the upper and lower protrusions either equal or with the lower lip being a shorter length than the upper. I think I get that the stagnation point would be both lower to the road surface as well as have a smaller surface area, with most of the stagnation pressure being directed through the cooling system. especially with a proper air dam and/or splitter.
As for the rear glass (*backlight?) I found my old protractor and tried to remember how to use it. From a square side-view image of my model car it looks like the peak of roofline to the tail edge of the trunk is about 10*. What I am picturing is a curved sheet of clear what-have-you over the existing rear glass and extending to the tail edge of the low rise wind. Like the Insight.
*Would an extended fast back @10* and approximately 10" longer than my stock configuration give me enough benefit alone to justify it? Or would that only be worth it as prep for extending the overall tail Kamm?

I think the basic shape is a really good starting point as the front has fairly smooth transitions and the rear is raked noticeably.
Still think the most economical option is the undercarriage streamline. I just gotta use RACEcar principles without it looking like RICEcar handiwork!

[freebeard]

For the nose bit, how do you mean vertical or canted backwards?

Take a look here:
Chevrolet Cobalt Body Kits at Andy's Auto Sport

They have 10 different options from conservative to full race. The former have an 'underbite' and the latter have an 'overbite'.



Notice the approach angle part. Ground clearance only applies to level ground. It always seems to be the gas stations with the high curbs to get over.

[OKXXFE]

That is actually the EXACT body kit I've been wanting. I know those are not the stock 15" wheels, and I'm pretty sure the car has been lowered. It looks good to me, problem is its 900$ plus shipping and install. gotta save for that.

[freebeard]

We have good taste.

If the full kit is $900, the front air dam should be some fraction of that. Still spendy, though.

[aerohead]

Originally Posted by OKXXFE

For the nose bit, how do you mean vertical or canted backwards? I am picturing the opening at the lowest point being perpendicular or slightly negative angle respective of the horizontal. I mean with the upper and lower protrusions either equal or with the lower lip being a shorter length than the upper. I think I get that the stagnation point would be both lower to the road surface as well as have a smaller surface area, with most of the stagnation pressure being directed through the cooling system. especially with a proper air dam and/or splitter.
As for the rear glass (*backlight?) I found my old protractor and tried to remember how to use it. From a square side-view image of my model car it looks like the peak of roofline to the tail edge of the trunk is about 10*. What I am picturing is a curved sheet of clear what-have-you over the existing rear glass and extending to the tail edge of the low rise wind. Like the Insight.
*Would an extended fast back @10* and approximately 10" longer than my stock configuration give me enough benefit alone to justify it? Or would that only be worth it as prep for extending the overall tail Kamm?

I think the basic shape is a really good starting point as the front has fairly smooth transitions and the rear is raked noticeably.
Still think the most economical option is the undercarriage streamline. I just gotta use RACEcar principles without it looking like RICEcar handiwork!

When your standing in front of the car,the 'face' should either be perpendicular to the ground,or leaning slightly away from you at the top.Either setup will have the same Cd according to FIAT research.
The actual hole for the cooling inlet IS your stagnation point,everything else will have curvature,steering the air around or over the nose.
If you run into interference (literally!),raise the nose to clear,then add a flexible wrap-around air dam to close off that flow from under the car.
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As to the rear glass (backlight) it's not certain how hard GM fought for low drag there.I like to think that it's optimized.Don't know.
We know that the K-form roof is superior as far as drag is concerned.I suspect that if you do the Kamm addition,that it will reward you at the pump.
As far as the 'angle' goes,you want to think in terms of curvature with 'local' tangent angles as with the Aerodynamic Streamlining Template tool at the top of the Aero Forum.