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Originally Posted by UltArc
It was clear, now it is not clear lol. Does anyone have resources I could review to expand my knowledge on this? I understand how a wing is going to hit the air and become an issue, but if it's creating less force than the underbody (which has less drag) wouldn't it noticeably increase the rolling resistance? I suppose RR should not be included in Cd lol
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We ought to select one vehicle and consider it with different configurations.
I have an SAE paper on Indycar aerodynamics from awhile back which included the wing research.
*The body was around Cd 0.28
*Adding exposed wheels netted around Cd 0.56
*Adding front and rear wings pushed the drag over Cd 1.0
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*At rest,the car weighed 1,400-lbs
*At race velocity the car weighed 5,500-lbs
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*You can imagine what the rolling resistance would do,but this downforce allowed the car to carry 235-mph through the curves.
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*The diffuser is a ground proximity device.Depending upon where the diffuser starts on the body,it can be optimized for low drag at shallow angles.
*With steeper angles,the diffuser triggers separation and allows the low base pressure of the wake to migrate under the car's rear,as far forward as the length of the diffuser.The low pressure acting on the underside of the diffuser creates a moment arm( torque) which attempts to pitch the car, rotate it around the rear axle,lifting the nose,creating downforce,which is balanced (hopefully) by the weight bias of the car.
*This 'torque' can be 'tuned' by varying the diffuser angle.
*And I agree that there bis probably a 'sweet-spot' at which you get drag reduction as well as a little downforce.
*If you drive at extra-legal speed and hit a wet spot,this extra downforce might mean the difference between hydroplaning or not.