Quote:
Originally Posted by viio
The red is where the air is at it's lowest velocity (i.e. most dragged). The roof spoiler is keeping that slow air out of the truck bed and actually directing it to (and over) your rear spoiler. If you didn't have that rear spoiler at all you'd have less drag as the roof spoiler would be sending air into the wake rather than into another object (rear spoiler).
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This is the opposite of what I've experience though.
My roof wing is actually directing air downward, doing so (I theorize) by removing the boundary level air though the slot and drawing the air above it down with it. This flow goes into the rear spoiler sooner and with more mass than without the roof wing. And yes, this means more drag, but I love the extra safety in bad weather.
This is the only way I can explain all the extra down force.
I'd be getting some lift and less drag according to the computer flow diagrams, this matches all the other data on "garnish" I've read. I think you did an accurate enough job, still wonder if the cant to the leading edge of the wing is responsible for extra redirecting of surface/boundary air.
I will have to tape some tuffs or longer strings in that area and film what's going on.
There must be a safe way to generate a small amount of smoke in front of the wing to record what is happening. Any ideas?