2nd look at CYBERTRUCK

[aerohead]

Now that we have some more definitive data for the RIVIAN R1T, I spent some additional time with CYBERTRUCK.
1) I located 26 vehicles with fineness ratios hovering close to that of the Tesla.
2) The 26 ranged from a high of Cd 0.29, to a low of Cd 0.137, with an average fineness ratio of 3.3252, and an average Cd 0.2157.
3) CYBERTRUCK's fineness ratio is 3.4269, a bit more 'narrow' than the group average.
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4) I located 11 vehicles with an aft-body percentage near CYBERTRUCK's, ranging from 49.7%, to 52.2%, drag coefficients ranging from a high of Cd 0.244, to a low of Cd 0.136, and average 50.806% and average Cd 0.1717.
5) CYBERTRUCK's aft-body is 51%.
6) CYBERTRUCK's drag coefficient has yet to be published.

[aerohead]

1) I took the Cybertruck blueprint and sectioned the drawing, to allow the body to be lowered to the 8-inch ground clearance, as it would ride at on the highway.
2) After scaling the overall height to that of all my light -table contours, I made the comparisons.
3) Whether Luc Donkerwolke knows it or not, Cybertruck, from its roof apex, to its upper trailing edge, fits one of Koenig-Fachsenfeld's patented / Dr. Kamm, 1930s FKFS K-form contours exactly, with the exception of the captured separation bubble which travels along with Cybertruck.
4) This contour is found in Bild 112, page 48, of AERODYNAMIK DES KRAFTFAHRZEUGS, by Freiherr Reinhard Koenig-Fachsenfeld, self-published, 1951.
5) Extrapolating the contour out to its conclusion, the long-tail Cybertruck terminates at a length of 305.68-inches.
6) 37.08% forebody.
7) 62.92% aft-body.
8) Making it the ichtyoid (fishlike) form found all over nature.
9) At 8-inch ground clearance, mirror-image yields a length / 'diameter' = 2.281:1 ratio.
10) With the wheels removed, and in ground reflection, the L/D = 2.59:1, near the ideal low drag minimum for a body of revolution.
11) A 73.98-inch boat-tail would drop Cybertruck close to its theoretical drag minimum. Which could be a simple inflated structure, for highway only.
12) It's all pre-engineered, and wind-tunnel tested.

[rmay635703]

https://damogranlabs.com/2019/12/tes...-aerodynamics/

Does what this guy is saying make any sense?

[freebeard]

It's all mooted by the pre-production prototype.

Overall dimensions may differ, flat panels are now convex, and the A-pillars are compromised by mirrors and a wiper.

[Vman455]

Originally Posted by aerohead

3) Whether Luc Donkerwolke knows it or not, Cybertruck, from its roof apex, to its upper trailing edge, fits one of Koenig-Fachsenfeld's patented / Dr. Kamm, 1930s FKFS K-form contours exactly, with the exception of the captured separation bubble which travels along with Cybertruck.
4) This contour is found in Bild 112, page 48, of AERODYNAMIK DES KRAFTFAHRZEUGS, by Freiherr Reinhard Koenig-Fachsenfeld, self-published, 1951.

Here is the Cybertruck* profile:



And here's Bild 112:



They aren't even close to the same contour. The curve between two points can take literally any shape--as we can see here with one curve and one line--and "matching" two points doesn't tell us anything about the aerodynamics of this truck.

*First prototype; video leaked last month purports to show a second closer to production-ready.

[Hersbird]

As long as we are just guessing let me guess the Cybertruck will be the same as a Ram 1500, Ford 150, and Chevy Silverado. That dunce cap roof does nothing for Cd and only increases frontal area. Flat roof for the wind and the win but that doesn't look punk.

[freebeard]

Not a match for Bild 112, but mainly because there is no plan taper.

The peaked roof doesn't [appear to] add frontal area, but it has severely compromised rear headroom. The peak angle is 204° so the brake is only 24°. The long vortex generating edges fore and aft reduce the air that goes directly over the top. There is no bed/cab gap.

[redpoint5]

I'm not concerned with rear headroom, as those people are getting a free ride and can't complain. They are probably also kids, so headroom wouldn't be an issue.

I wonder if vortex generators near the peak could help with flow attachment?

I still want one of these, but I wonder if I'll maintain that opinion as other trucks compete? 6-seating is a big factor for me.

I'll probably never get an EV truck, because a truck is the last thing I need (we've got 3). 6+ seating is probably better accomplished with a Model Y, Model S, or Model X.

[freebeard]

For a truck I'd want something more like this:

[rmay635703]

Considering the competition
can be up to $100000
Can have under half the range

It’s possible this will be the one that makes “practical sense “
Even if “ugly” and not playa by modern standards