Quote:
Originally Posted by California98Civic
This raises questions for me. The tuft testing I have done of my sixth gen Civic coupe shows a recirculation zone for about 4 or 5% of the lid/window area near the spine of the car. Air reattaches a few inches before detaching from the trailing edge of the trunk lid. Good. And better than I thought. Certainly a solid well-placed surface is better than a recirculation zone for allowing air to slip along, no? Certainly the longer, descending-angled raised lid and lip would slow the air more than the 4" where the air currently reattaches, therefore gaining the pressure benefits you describe here, no? It seems to me the key is making sure the contours of a raised lid do not add drag, and if they don't that a 2% drag reduction should be possible. Modest, but measurable in FE terms in a careful test, no?
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California,a sketch would really help.I think I understand where you're going.
Circulation is bad.Energy of rotation cannot be converted to pressure.
Even if the air strikes the trunklid,while reducing lift,it may still impart sizeable drag due to where the air separated.
The spoiler,if its trailing edge is near the 'Template',will wall off the lower pressure in front of it from the wake behind it.
A Porsche 914,Karmann Ghia,Lotus Europa,etc.,all have downward collision of air striking the body behind the backlight.The Lotus shelf extends far enough back to hit the 'Template'and will not allow the wake to migrate forward to the backlight.This is not the case for the 914 or Ghia.
If you watch the Porsche at El Mirage Dry Lake you can clearly see the dirt of the wake come right up behind the backlight and enter the engine inlet grille.Nasty!
Minimizing the circulation is something the spoiler(s) can help with,but even if pushed to the 'Template' you suffer some loss.