Quote:
Originally Posted by Piotrsko
Then what you are both saying is that there is a huge relative high pressure bubble at the top of the apex and that the body is allowing the migration off and then some low pressure sucks it right back onto the flow, maybe even not becoming turbulent? Id might accept that at super critical reynolds numbers, maybe. It would also indicate that much more thought has gone into the design than goofy marketing.
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1) Advancing into calm air, of pure static pressure, the atmosphere tends to 'hold' the flow against the contour.
2) The turbulent boundary layer ( TBL ) is moving towards the body's location of minimum pressure, it couldn't get any better.
3) The geometry of the nose, over the bonnet, is such to produce an immediate flow separation, then nearly-immediate flow reattachment, in accord with a Lanchester/ Prandtl surface of discontinuity, with insignificant drag penalty.
4) Flow, continuing up the bonnet/windscreen, will experience a favorable pressure gradient all the way to the roof apex.
5) Flow spilling over the front quarter panel and A-pillar will enter a regime of ever-increasing velocity, and ever-reducing pressure, an ideal situation for a TBL.
6) Nose side chamfer provides the same surface of discontinuity and low penalty.
7) Nose lower converger ditto.
8) According to Feysal Ahmed Adem, super-critical Reynolds number will be established 30mm downstream of leading edges.
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9) As flow tops the roof apex, it's within a few degrees of Koenig-Kamm's streamline contour, a 'GO' as far as the EPA's 1977 research on fastback low drag flow attachment guidelines.
10) The 9-degree departure angle for the roofline also happens to agree with the lowest drag angle achieved with the Ahmed body, prismatic body drag research.
11) The 2.75-degree inclined greenhouse is an industry first, as well as the beltline body crease, which may act as a flow fence, both of which 'could' be used to 'tune out' attached longitudinal vortex pairs at the roof intersection.
12) Aft of the rear door, there's a strip-strip built into the body, which could aid tumblehome TBL stimulation, as VGs are known to do, and with a 'structure' which cannot be destroyed at a commercial car wash.
13) The built-in ' 1982 Pop-A-Top '/ Feysal Ahmed 10-degree slant topper' may provide the 16.19% drag reduction by itself.
14) With an aftermarket airdam and diffuser, CYBERTRUCK has a shot at Cd 0.25, at OEM length, not a far reach considering SPIRIT indicated as low Cd 0.17 in a BEV configuration.
CYBETRUCK may go down in history as one of the most thoughtful design exercises to emerge from an American manufacturer.