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Originally Posted by kach22i
Okay, sounds like we need an "A" and "B" here at the top of the window. The "A" will be a vortex generator, the "B" will be the "cutoff" type. I have both examples shown, but did not call out the differences.
Yes, this term can be applied if at the idea angle or slope. Is there another name if we just extend out at zero angle? And will that zero angle extension be a plus or minus drag wise?
On the old air cooled 911's, the tea tray and whale tail type spoilers add little down force, and don't help out the drag very much either. What they do best is to allow the cooling fan to draw in air from the top better by altering the pressure zone above the intake vent.
I'm going to look up that Ernie Rogers project. I suspect the New Bug's air flow breaks off later, maybe at the bottom of the window, in lieu of the top on older air cooled Beetles.
EDIT-1: If this is to be trusted, the New Bug air breaks off much later.
Beetle Aerodynamics / Roofspoiler
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I'm very suspect of that image.If the arrows were drawn to agree with tuft orientation they would not reveal vorticity,only surface effects.
The New Beetle,as the original are both pseudo-Jaray cars.Their rooflines are too 'fast' to support attached flow and other such rooflines,when investigated in the wind tunnel,revealed attached-vortices which tended to 'hold' the tufts down the centerline of the roof slope,but would give a deceptive interpretation of the flow.
The vortices themselves produce remarkably high drag.Spoilers might break these into smaller eddies,but the energy is permanently lost to viscous attrition downstream.