Quote:
Originally Posted by narclepticfool
Ill get some more picture of that.
What do you mean about adding 1/2 round tubing to soften the edges? Does that improve the aero even more?
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1) you've converted a 'notchback', to a 'fastback,' and fastbacks are the most sensitive body type to 'tumblehome' and edge radii influence, because of vortex-related drag issues.
2) Baron von Koenig - Fachsenfeld tested 'fastbacks' specifically for this tumblehome/edge radii effect, and registered 16% lower drag, when the side-to-top intersection was 'softened.'
3) It requires 'compound' curvature. which is the most labor-intensive shapes to fabricate, and scares off all but the hard-core streamliner.
4) And the lack of plan-taper in the truck box mandates degree of compromise, as one would literally have to discard any OEM truck box, and start from a clean sheet of paper ( or CAD ).
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5) another observation about your trip mileage. There's a likelihood that the receiver hitch cargo carrier was acting as a crude boat tail, filling the void which would ordinarily be nothing but turbulence.
MOTOR TREND did an extended A-B-A road trip with a Pacifica and cargo carrier, and while reluctant to attribute higher mpg with the carrier, did experience higher mpg with it, compared to without it.
6) Member, Brett Herndon, of Littlerock, Arkansas, created a patented 'Aerolid', and 'aero tail' for the 2012 model F-150. His tail was good for delta Cd 0.031 in the wind tunnel.