[3304hl]

Hi
Came to this via Jalop and have read through all 24 pages.
Here's a few random thoughts on "aero" from the deep recesses of my mind thanks to the 1973 OPEC "oil crisis"

First, A "teardrop" isn't actually the ideal shape for a car unless of course you're planning to drop it off a cliff. To start, gravity distorts a drop of water in ways it doesn't a car's airflow. Next, a teardrop has clear air all around it; a car doesn't. This is why all serious Aero testing is done in an open chamber tunnel with a rolling road. Interestingly, real "road testing" produces far more accurate results than a lot of very expensive tunnel time and it's way cheaper!

Regardless of how slick the bottom of your car is, it isn't as good as the top bit. Any air forced under the car is compressed by the road surface, making it a "heavier" fluid; ie: more drag. This is why Nascars use that wacking great front spoiler. You can pick up lots of MPG here.

The ideal departure angle for the rear deck should not exceed 7 degrees to maintain ideal Laminar flow regardless of all the teardrop talk. If you look at the "smoke" pic of the Insight you can see the smoke at the rear of the deck is seperating somewhat( it's thicker). This indicates that it's generating lift and drag. If you can find a pic of a second gen CRX from Europe, they have a slick little rubber duck tail that flattens out the air flow. You might try something like this on you car and see what comes of it.

Re: the discussion of flat back or open, my work on my old Hornet hatcback in '73 says open. Air coming off the bodywork creates vortex drag that acts on the rear of the car. The extension of the bodywork moves the vortex further from this panel. There's a lot of work to be done here as it's not nearly as simple as it sounds. Different sizes of cars with different aspect ratios produce different results here. I used an array of aluminum rods from an old TV antena( remember those?) mounted to a plywood panel with the fabric tufts to test this out. You may be surprised at the results! Controlling the air rushing under the rear quarters of the car really helps a lot. Rear "diffusers" aren't just about downforce.

gotta go.
hope this gives you a few new ideas to play with!
And your friends think YOU'RE strange; (insert evil laugh)