Quote:
Originally Posted by Sven7
So essentially it's using a vortex on the rear window and trunk area to guide the upper air over it cleanly, while creating downforce. Kind of like a virtual Kammback, if you will. How does this effect help the attachment of airflow?
Is there a practical difference between those Nascar type spoilers (Barracuda) and the flat ones (Monza)?
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Both can give the outer flow a place to re-attach to,and then flow beyond there will skip over (you must pay for energy to feed the circulating vortex though!) which is what cuts drag.
The NASCAR spoiler angle will vary from track to track depending on length,bank,and speeds.And they'll change after qualifying runs,once they get into 'traffic' of racing,where the surrounding cars are getting or losing their air.The angles will be a compromise between speed and downforce.
At Bonneville,the spoiler will also be a compromise between drag and downforce with the added variable of parachute deployment.Typically,the drag chutes are angled to fire on an upward trajectory to catch the air above the spoiler line.Wheel traction is a big issue at Bonneville.Some of the cars are so powerful that they can spin the wheels at many hundreds of miles per hour.And at those speeds,if the car gets sideways they become crude airfoils and lift off.Very scary!
Streamliners fire straight back,but they're so clean the chutes have no problem.Terry Nish includes VGs at the back of his Royal Purple streamliner to guarantee quality onset flow to the dual chutes.If they fail,it's very hard on the brakes even if ceramic.He told me( if my memory serves me) that he coasted for 10-miles once when the chutes failed to deploy.