Detached flow/
 

Maybe this has been covered before, but if so, i've missed it.
In pictures of teardrops the slope clearly exceeds 12 degrees as it slopes rearward. Yet I thought flow detaches if the slope is steeper than that.
How does flow stay attached as the slope steepens?
I'm wondering about doing a 3 to 4 foot Kammback with gradual slope on a van.
Thanks in advance,
Ray Mac

I read an article in a magazine a long time ago that said 30 degrees is the steepest you can go.

The nose and tail interact to some extent. Full optimization is at least a four dimensional problem... :)

If you look at the directions for the "streamlining template" it gets progressively steeper up to 22º.

teardrop slope
 

*The teardrop is borrowed from Jaray's airship design and the 'pumpkin seed' automobile body which evolved from it.It is designed for zero separation.
*The progressive curvature allows for continuous momentum interchange from the outer flow into the turbulent boundary layer.This allows for deceleration and pressure regain as the flow moves rearward.
*W.A.Mair's research of 1968 determined that 22-degrees is the maximum tangent angle which can maintain attached flow.The 22-degree angle is not achieved until around 1.3 body diameters downstream of the maximum body cross-section and continues as a straight line cone to a point.
* The 'Template' is based on a 2.5/1,Length-to-Diameter airship in ground-reflection(after Jaray/Prandtl),with the ground clearance cut away.
* At no point does the 'Template' violate the 22-degree dictum and it produces zero separation.
* For the 'Template' to operate to full potential it must be used as illustrated.If you go steeper sooner,you're inviting separation,exactly against the sole premise of streamlining.