Quote:
Originally Posted by JacobLeSann
It looks like flow reattaches at the boot and separates cleanly off the top end of the trunk. I’ve posted some tuft-test photos here:
https://ecomodder.com/forum/showthre...tml#post675015
The 2022 civic coupe has a very neat rear end. It’s a very true-to-form fast back and has some sharp separation edges at the rear. My issue being that my rear end isn’t really like that at all. I can’t really get it to take that shape without a lot of modification, hence why I’m looking at raising the lid. The 2022 Civic sedan is a bit of a better model. You can see the progressive raising of the trunk’s height over the different model years.
I think I might go ahead and test out some prototype aero mods. I want to raise the lid toward the base of the windshield, and drop it down towards the car’s rear,, flowing out into a rear bonneville-wing type extension. I think that would work very well as a fastback substitute. |
Of the three predominant body styles for production vehicles, the notchback is the most mutilated, and does not lend itself to aerodynamic geometric relationships enjoyed by fastback and squareback vehicles.
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Kamm's last K-Car, constructed in 1958, at Battelle Institute, Germany, was an Auto Union/DKW notchback sedan, converted to a 'kammback', via a composite integrator, directly overlaying the OEM notchback afterbody.
Once 'converted' to a K-form, additional streamlining is simply a modular, plug-and-play exercise, reducing drag as a function of elongation.
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Wolf-Heinrich Hucho's 2nd-Edition is full of afterbody optimizations involving :
* geometries as a function of roof length as a percentage of total car length
* roof camber-contour if any
* backlight angle
* C-pillar geometry
* boot height saturation
* boot length saturation
* adhered vorticity
* attached counter-rotating longitudinal vorticity
* separation-induced downwash ( false-attachment )
* vortex burst
* spoiler undershoot
* spoiler overshoot
* spoiler saturation
* etc.
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As to the 'Bonneville' spoiler, you might be interested in the 2007, Ford Fusion notchback, 999 LSR car, which was aero-modded, from Cd 0.34, down to Cd 0.21.
A technical image of this car indicates the 'coincidence' of a perfect alignment of the tearing edge of it's Bonneville spoiler and the AST-III.
You may discover the same 'coincidence' for Chevrolet's Cobalt ECOTEC LSR's Bonneville spoiler tearing edge.
The Opel Calibra's rear deck optimization also indicates a 'coincidence' of it's tearing edge aligning with the AST-III.
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There is some probability that HONDA has already optimized the rear of your car, for what it is, in the context of the product committee's design specification. And Honda is very tight-lipped about aerodynamics.
The 2022 Coupe afterbody silhouette is likely just a concession to more stringent CAFE standards.
You can do better, but anything significant would require 'losing' the notchback.
The best images for the Cd 0.1716 M-B EQXX, Cd 0.175 Lightyear Zero, and Cd 0.1764 Think Flight Subaru Impreza, indicate the coincidences for exact matches to the AST-III.
It's the only thing I know to be a sure thing.