Detached flow/

[fud2468]

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

[winkosmosis]

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

[KamperBob]

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

[COcyclist]

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

[aerohead]

Originally Posted by fud2468

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

*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.