Late Model Stock Car Aero

[nolin78]

I have a question regarding aero effect on a late model stock car with an "ABC" body. These bodies have templates that require everybody to have the same dimensions. These rules leave the underbody of the car open to design. These cars are tube chassis and pretty much open to the air underneath. we have a 4 inch ride height rule that we have to follow. heres some pics of last rears car. it is not an "ABC" body but very similar to it.

http://www.ryannolin.com/highlights_subway_milton_carshow.html

that picture shows the basic body. You cant see it but there is a 5 inch spoiler at the deck lid.

With that said, i was wondering if you guys know if there is anything i could do underneath the car as far as areo goes that would increase downforce even if there is added drag?

Ive heard there is benifits to "skinning" the underside. I think this would help speed air flow, thus lowering pressure.

is that true?

thanks for your help

ryan

http://www.ryannolin.com

 

[TVP]

Yes, making the underbody smoother will reduce drag. If it is flat and continuous, without too many seams, gaps, etc., and the underbody is raked from front to rear a few degrees, it is possible to generate downforce (higher velocity = lower pressure). The book on race car aerodynamics by Katz is a good reference. You can obtain it from Motorbooks.com.

 

[evelrod]

Good looking car, Ryan. I like the paint scheme.
Adding a properly designed full, or even partial, belly pan with a decent exit diffuser will decrease drag and increase downforce...however, I don't see ANY stockcar sanctioning body allowing this degree of modification. Common at Bonneville and SCCA sports racing, open wheeled formula cars and sprint cars, not common on stock cars. You can try, as Smokey Yunick did, to clean up the undercarriage and 'fare in' all the little things that 'stick out' into the airstream...might get by with that. You'll need to be REALLY creative to get by NASCAR tech.

Rod

 

[apex944]

That last couple copies of RaceCar Engineering had some excellent articles on undercar aero, including a feature on Cup Car aero. Check it out.