Quote:
Originally Posted by AeroModder
One thing that's crossed my mind is kammbacking sedans without boattailing them increases the size of the rear area, thus increasing the size of the wake. Hatchbacks can get away with it because their rear ends are already large, and the kamm reduces it. Since airflow still reattaches on the trunk, the "suction cup" isn't as large, even if the air is perfectly clean.
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This,
Quote:
Originally Posted by dkunitz
Would it make sense to extend the trunk surface? I've seen sedan-shaped drag cars with enormous extensions that continue the line of the trunk. I think the vortex created under the extension might be more beneficial on sedans where you want to maintain easy access to the trunk.
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And this.
It may not look like it, but the airflow is partially re-attaching at the trunk lid. Putting the kammback on there interrupted that airflow, and made a larger drag area. Instead of the airflow going down to trunk level (or close), it is breaking off where the kammback ends. Extending the trunk lip backwards will actually help pull the airflow down and break it off lower.