Quote:
Originally Posted by UFO
That sounds like a "vortex generator", which may induce more drag than it reduces. My understanding of the roof spoiler is to provide a sharper cutoff to the airflow to reduce some of the drag caused by air partially detaching along the steeper back slope. By detaching the air completely you still have the full drag of the entire frontal area.
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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.
Quote:
Originally Posted by UFO
Otherwise known as a Kamm back, and if long enough makes a huge difference.
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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?
Quote:
Originally Posted by UFO
Ernie Rogers did a flat spoiler at the window base on his New Beetle and demonstrated a Cd reduced from 0.39 to 0.30, similar if not slightly better than the VW Golf.
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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.
http://www.gerrelt.nl/section-aerody...planation.html
