Front aerodynamics... need help!

[serialk11r]

Ever seen an F1 car? High nose yea?

Air under the car is not necessarily bad if the underbody is smooth and shaped correctly. Because the ground acts as a barrier for airflow (ground effects), channeling more air under the car gives you more downforce because the air will be forced to speed up where the body is closer to the ground. With the disastrous aerodynamics of most cars this won't work very well though, and that's why when it comes to diffusers and splitters you really have to pay attention to what they're actually doing, it's not like a wing where you just raise it really high, give it a big angle of attack, and have some kind of result that is at least partially desirable.

[kask2_6.0]

Originally Posted by serialk11r

Ever seen an F1 car? High nose yea?

Air under the car is not necessarily bad if the underbody is smooth and shaped correctly. Because the ground acts as a barrier for airflow (ground effects), channeling more air under the car gives you more downforce because the air will be forced to speed up where the body is closer to the ground. With the disastrous aerodynamics of most cars this won't work very well though, and that's why when it comes to diffusers and splitters you really have to pay attention to what they're actually doing, it's not like a wing where you just raise it really high, give it a big angle of attack, and have some kind of result that is at least partially desirable.

Spot on. A splitter/diffuser is not about keeping air from under the car. The purpose is to split the air smoothly around the car and reattach it with as little turbulence as possible. The smoother the air under the car, the cleaner a proper diffuser can reattach it creating a low pressure area and thus downforce. Unfortunately aero is not really a cookie cutter science and every car will have different requirements and different methods will work.

Surprisingly the splitter also has a large effect on the rear of car. But without having a flat bottom (like any race car) I don't there would be any gain with a nose like that.

But here is an example of a DP car with that type of splitter:

[raul]

Your worry is a legitimate one, but one that can be solved.

When do you want downforce the most? Corners.
When do you want a lower drag coefficient? Straights.

When you're about to take a corner your car will dive some. This will reduce the angle of the center part of the lip and most likely end up being pretty parallel to the ground, not having to worry about lift. In addition, downforce will be added directly to the corners (where the wheels are) to increase downforce sufficiently.

When you are in a straight, the car's front will inevitably lift a bit, letting some are under the car. Since air is hitting the center mass of the car, it will create drag and probably a bit of lift. But having the lip come up in the center will let air flow through the bottom of the car easier, resulting in less drag. The design offers a good compromise between downforce through corners, and less drag on the straights.