[aerohead]

Originally Posted by CFECO

I was thinking, that "Follow the template always" may not be the best idea. If we had cars with the same front shape as the ideal, then yes, the rest should be as close to it as possible also. But since we have rounded off box shaped front ends, with setback windshields, the airflow will not match the ideal from the start, so I'm not sure the rest, always will either. Without a windtunnel, who knows? Back when I was doing cylinder head work, the flowbench showed me the air "wanted to go places" that I didn't always expect. A car with a blunt front end seems to like the waist area pinched in, looking from above, which is where the template shows it to be the widest. I imagine that is where the air is coming back to the body at an angle, and wants the body to match that angle smoothly. I think the speed matters also, higher the speed, the farther back the pinched in area should be. I realize this thread is all about the rear area, I'm thinking the air is coming back "down" from going up the windshield, and hitting the roof before the rear glass, and maybe needs the roof raised in the center in order for the spoiler to work. Just a thought!

As long as the onset flow from the front of the vehicle is attached to the point of maximum body cross-section,the vehicle should respond favorably to the 'Template'.Flow behavior will be constant from 20-to- 250 mph and the body need not vary as a function of velocity.It's different physics compared to a flow-bench.Exo-duct,not duct.