Body Work (painting, waxing, aerodynamics)

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Regardless of how experienced you are, or how much money you've dumped into buying and/or modifying your track car, you can't avoid the wind. Finding a cleaner way through it will always be an element of driving and racing.

Vortex Generators

The turbulence over and behind a race car, especially a sedan, seems significant, and if something can be done to reduce it, or more appropriately, control it, then advantage should be gained.

Vortex Generators are small aerodynamic surfaces that adapt the flow of air. They're used extensively on small airplanes, and have started showing up on semi-trailer rigs. On Semis, they help eliminate the turbulent, low pressure area behind the rig, bringing a more laminar flow behind the rig. They are said to reduce fuel consumption, and provide a smoother ride. For graphics of how they work on trucks, see:

It seems like this same concept can be applied to auto racing as well. There is an anecdotal reference on the airtab site about a 914 who used Airtab VGs to bring the airflow from severe back glass on the 914 down to the spoiler on the back. Also, the Mitsubishi Lancer Evo VIII MR has VGs along the back end of it's roofline. You can see them clearly in this picture:

Their engineers did some studies to determine what shapes to use, and have made them available at:

A more "accessible" series of articles can be found at Unfortunately, it looks like after a certain number of views, autospeed asks for a subscription. Those who know me, know I'm cheap, so until I decide to spring for the online copies of Issues 400 401 402 and 403, you'll have to live with my summaries. If you want to take a look, see the links: - issue with the final article - part 4 of the article

The authors put wool tufts all over the back glass of a prius sedan. They started with a few VGs in the center of the rear roofline, and added more, showing pictures as they were added. There was a clear indication that the VGs improved the flow of air over the glass. This configuration is very much like that of the Evo in the picture referenced above.

It would seem there there are many applications where VGs could be put on the roofline and improve the flow of air down to the spoiler, increasing downforce without adding drag. Seems like a win-win.

The article did recommend the airtab style VGs shown at

Vortex Generators under the car

There is some anectdotal evidence that VGs under the splitter at the front end of the car may help organize the airflow under the car, keeping it from interacting with the uneven underside. Obviously, if you have a full undertray, this wouldn't help.

Vortex Generators on Helmet

Bell has a new series of helmets that have vortex generators along the sides to help reduce buffetting experience in open cockpit racers. Google 2005 BELL VORTEX to find examples.

Experiments that we'd like to see

Can vortex generators on the rear end of formula style cars, and along the top of the wings of formula style cars decrease the drag of the wings, and reduce the turbulet low pressure area behind the car that provides a draft for followers?