Aerodynamics

[EGSMachine]

i am wondering about what one can do to make the underside of a car make its own downforce.
so here is what i think so far:

1) you can not make the whole underside one level plane. if what i understand about a wing, the air above the this plane is moving "faster" which creates a low pressure area for the "slower" air to "fill", which creates lift.

2) divert the air. front spoilers move alot of the air out to the sides of the car, buit there is still some air underneath the car. how can i divert this air to create downforce? i can try making vanes or skirts that push the air out the sides. what are some other options? i have seen model cars of some race cars, but i don't know how accurate they may be.

so i have to get the air out, or make it work for me. i want it to work for me.

thanks,
e

[Obin Robinson]

i have been working on this EXACT same thing for the 924. here's your answers:

1) you HAVE to make the underbody smooth under the driver's compartment. this can be accomplished with a bunch of sheet metal. the key here is cleaning up airflow.

2) a diffuser under the rear of the car

3) a chin spoiler under the front bumper, and a spoiler on top of the hatchback at the rear. unfortunately, the best spoiler for the 944 is one that is really high up and about at the height of the roof. you can thank the riceboys for making this mod look so BAD despite the fact that on a REAR WHEEL DRIVE CAR (unlike their hondas) this is what is necessary to keep the car on the track.

you're correct about the wing shape, but there's a lot of other factors working to an aircraft to achieve lift.

the first thing i'm working on is going to be a smooth underside. the only way to get it really smooth unfortunately us by relocating the exhaust to exist out the passenger side door. i'm not ready to go THAT far just yet

good luck!

obin

[EGSMachine]

i realize the clean up is necessary, i guess i was wondering, How do i make the car make a venturi under there. i have heard that some of the race teams direct the airflow so that it pulls the car down. but how? if i have 4" to work with, what are my options. i saw one thing on an NSX, it had channells runing laterally to the car. it seems to me that this would cause turbulance, not downforce. i new about the rear diffuser, and i am going to work on that soon. the rear wing needs to be high to get it into "clean" air to be most effective.
thanks,
e

[3sonfather]

Just a thought - perhaps there is something to be learned from the 928's. Don't they have a front louver that is actuated with respect to speed to create this same effect?

[EGSMachine]

Do you have a diagram of it and how it works? or know where one could be obtained?
thans,
e