This is the area you are referring to?
It appears the air pressure is lower on the roof vs the side since the upper tufts are getting pulled up and over the edge. This edge will be difficult to round. At best it will be between 1-2 inch radius. However the angle as it moves back does reduce. It is hard to see but the angle starts at about 75 degrees and ends around 45 degrees. The roof cross car dimension is consistently 48 inches. So with the edge following the truck side, as the roof comes down, the angle changes to accommodate. Here's a view of the recent CAD:
As for rear visablity, I and sticking with side mirrors.
Quote:
Originally Posted by aerohead
Flow looks good!
It does indicate the formation of attached longitudinal vortices, along the roof / sail panel intersection of the cap, which carry relatively high drag.
A solution would be either chamfering, or softening with a radius matching that of the cab.
Radius is best, but also the most intensive, as far as fabrication goes.
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Also, you're creating a 'fastback' roofline, which is the most sensitive of all roof designs to tumblehome.
If you stand at the back of a HONDA Fit, looking forwards, you'll notice that the A-pillar, B-pillar, and C-pillar are all at different tumblehome inclinations.
The airflow really 'likes' this.
Again, these subtle features are the 'most expensive' to fabricate.
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