Quote:
Originally Posted by landspeed
BeeUU - I am wondering - would that lip on the boot lid make any difference?. I thought that there would be turbulence from the top of the rear window when driving (due to the sharp drop-off), so wouldn't the lip be in the turbulent area and so make no difference anyway?.
I might be wrong, and if I am, I will be adding a lip to my car soon
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Landspeed-
There is still flow there, I have a few pieces of evidence that this is so.....
1) "Aerodynamics of Road Vehicles" by Hucho indicates a lip reduces drag on a notchback up to a height of 20mm with an approach angle of 20 degrees. Lift drops too.
2) Water/dew patterns on the trunk and window shows a flow from the "C" pillar and a vortex impacting the trunk lid.
3) Dust/water collecting on the negative pressure aft surface ending at the trunk horizontal surface.
4) I happened upon a technical paper for calculating fluid flow that was using automobiles for an example. The existing data example was for a 405!! How lucky is that? It indicates that while the airflow separates at the valley of the window truck lid, it reattached at the aft edge of the trunk lid. So, if the computer says so it is true...
5) Most fuel efficiency specials have a lip on the trunk. This was true in the 80's and they appear on all the hybrids models in the US, so if the guys with the wind tunnels think it is worth the effort and the accountants let the engineers spend the 5 bucks then I will give it a try.....
Hucho indicates 0.01-0.02 reduction in Cd, I dont have time to make belly pans yet, it took less than a minuet to build!!! Every bit counts when trying to get on the top 10 list.
Look out Z, the weather is warming here!!