Quote:
Originally Posted by Phase
Well I was just going off Julian Edgar saying 10 percent in his videos. I’ve seen a few cars with much steeper rear diffusers like the polestar 2 EV. Obviously the mock up diffuser I made is less than 10 percent. Pretty much was just trying to continue and elongate the existing panel and angle by another foot
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I can't address the videos. Unless the rules have changed.
I tried to give you insights into the mind of someone who witnessed low drag firsthand. Hucho's Cd 0.15 'template' of 1978 didn't have a diffuser.
Volkswagen's lowest drag, Cd 0.14 'Flow-body' of 1981 had a 'slow' diffuser.
I have tuft-testing images of a 'steep' Lamborghini diffuser experiencing 100% counter-flow. There IS an angle at which air behind the car begins to flow forwards down under the car, not visa-versa.
There may be caveats attached to specific designs that you'd want/need to know about.
Volvo and Polestar aren't necessary known for low drag.
'High-performance' cars will pay a drag penalty for high speed stability.