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Old 12-14-2019, 12:23 PM   #11 (permalink)
aerohead
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eyeballing or..................

Quote:
Originally Posted by M_a_t_t View Post
I can't find the diagram I remember seeing, but I was hoping to try and get the airflow to be re-directed away from the roof at the windshield and have it come back down and reattach following the roofline. Similar to what seemed to happen with the hood to windshield model (post #3).

Are you eyeballing the slopes or calculating? I have been eyeballing. When I overlay the template (I understand has limitations) the tail pretty closely matches the upper shape. I would like to do some tuft testing, but don't really have the stuff required to record it.






Thanks for finding that. They don't have the correct year escort though




Do you think a gurney flap at the tip of the tail would help flow? I remembered I have 2 wide angle dash cams I might be able to use to record from a chase vehicle. I will try to get something this weekend.
In Wolf Hucho's 'Aerodynamics of Road Vehicles,he presents empirical results of aerodynamic testing,dating back to 1922.
He dedicates an entire section to forebody design,drawing on Jaray,Fachsenfeld,Kamm,Waters,Pawlowski,Carr,Ahmed ,Hoerner,Emmelmann,Janssen,and Hucho.
From the visual schematics,I can just look at your rendering,and know that you're already at saturation.There'll be no problem with attached flow over the roof peak and onto the rear slope.
The important part is the slope/contour back there.That's where your streamlining potential is.The 'template' contour is derived from the lowest-drag half-streamline-body of revolution.My model which used it,measured Cd 0.12 just as predicted.You'll never find a shape with lower drag potential.That's why I shared it.

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