Technical nerdism

"Drakkon- Most Glorious and Upright Person of Genius" (rex-imperator) 12/14/2015 at 21:51 • Filed to: Tech

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After the discussion earlier about the craziest aero devices, this is an interesting post to tease out the thread. The attached article is about diffusers in particular, but interesting to me, from the ‘basic research’ perceptive. Not super advanced aero, not car-specific devices, but answering the question what exactly are those things trying to do under there. Linked article by Willem Toet.

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tromoly > Drakkon- Most Glorious and Upright Person of Genius 12/14/2015 at 22:36

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His comments on 3D flow brings up a very big part of under-car aero, keeping high-pressure air outside the diffuser from bleeding underneath the car is vital to getting good performance.

One additional thing is that a wing can be used to “pump” the diffuser, effectively making the air flow out of it faster and creating a lower pressure underneath. Here’s a couple pictures of one such arrangement (the upper edge of the diffuser is the honeycomb material).

Drakkon- Most Glorious and Upright Person of Genius > tromoly 12/14/2015 at 22:56

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If you look on the article today about craziest aero, they have a photo of the Suzuki hill climb car. I have a photo annotation that the bottom of the splitter and the side valance skirts were both consumable urethane foam. As you described, they want the shirts as tight to the road as conditions would allow, but if the skirt were made of stiff carbon, it would break off on impact with a rock out curb. Since it was foam it could be chewed away and leave as much material as possible.

tromoly > Drakkon- Most Glorious and Upright Person of Genius 12/14/2015 at 23:18

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SCCA A-Mod guys run hinged skirts that can move with the contours of the road, same idea different execution.

Drakkon- Most Glorious and Upright Person of Genius > tromoly 12/15/2015 at 09:56

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Now that Pike Peak is 100% paved, maybe we would see this solution there, too.