Quote:
Originally Posted by apgrok1
So a roof tail would be bad
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On a notchback yes as it would potentially prevent the flow to reattach at the trunk. On a squareback they can be desirable if they taper the roofline down at a 12 degrees or so angle.
Quote:
Originally Posted by apgrok1
VG's are good
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On a notchback yes, they can help reattach the flow on a shorter distance. On a squareback, which is a lot like a trailer, there are some sources saying that they can be used to create what looks like a boat tail made out of vortices (SAE paper 2003-01-3377 as an example).
VG's have a minimal impact on FE however you look at it though.
Quote:
Originally Posted by apgrok1
the longer the tail fairing, the better, right?
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Yes. Past a certain lenght the drag reduction is marginal though.