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Building an airdam


RebekahsZ

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In Competition Car Aero by McBeath he talks about air dams vs air dams with splitters. He says there is virtually no difference in drag and a significant increase (10%) in downforce when tested in CFD on a NASCAR model.

 

The hesitation I'd have about running a splitter is not balancing it out in the rear. It's really impossible to say how big an imbalance there will be if you ran it as pictured. What you're doing doesn't really correlate to the wind tunnel testing very well because all of those examples had the front end relatively open, and your speeds will be higher so the effects will be a lot greater. My gut tells me that I wouldn't run that air dam with a splitter without a spoiler on the back, and preferrably a wing. For a strictly one mile straight line, I'd run it without, then I'd put the splitter on as a separate piece and figure out the aero balance at a road course.

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It will be only for the smooth, straight concrete track at Wilmington, Ohio.  High enough to clear the runway lights in the staging area, but low enough to require removal to get the car on the trailer.  I would never want to challenge roadcourse curbing with this thing-its gonna be pretty fragile.  But, I am learning a lot, which I hope to let me make or modify an airdam for road course that lets me improve my brake ducting situation (or lack thereof).

 

JMortensen-do you think that adding this little down force on the front end will cause LIFTING at the rear?  If not, I should be fine.  If so, I may need to be on my toes.  The car was stable at 167 and didn't demonstrate any negative behavior.  The purpose of this airdam is first and foremost to reduce drag.  I appreciate your info suggesting that adding a splitter should not negatively affect drag, so that is encouraging.  Any downforce I will take as a bonus.  Thanks again and feel free to comment or suggest as you see fit.  At this point, I really don't have time before the race to do anything to the rear of the car.  I'd like to make that a separate project for next year.  I wonder how much drag the rear spoiler adds....

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Polyisocyanurate foam 1/2-inch sheet insulation board from Lowe's. It has foil on one side and plastic on the other, but it is easy to peel off. I put some polyester resin (the nasty-looking brown variety from the hardware store) on some foam as a trial before I left for work this morning. Heading home to check and see if it melted, or not. Photo edit shows that the foam held up to the resin.

post-5903-0-58124700-1431741398_thumb.jpg

Edited by RebekahsZ
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Supposedly you should be able to stand on a splitter without it breaking. If it generates 200 pounds of downforce at speed then it should be able to support 200 pounds across it. Just some food for thought before you go dragging something down the road.

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We shall see, but I think that's a little bit of bull. I don't think I've EVER seen a splitter that I could step on with a clear conscience (or without getting an ass whoopin')! Whenever I'm looking at a car with fancy aero bits, the first thing I do before getting close to it is take my shoes off. But this airdam will have more rigidity than the nose of my old longboard, and it will also have more strength than Clark foam and a 3oz layer of glass.

Edited by RebekahsZ
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OldAndy-I for sure don't have your skills. It's looking pretty rough, but I'm making slow progress. This will be a rough airdam and if it doesn't fall off the car it will have one purpose: Ohio Mile. It probably won't even have primer on it in time.

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