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Old 01-20-2024, 12:50 PM   #1 (permalink)
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NIO EC6 active rear spoiler= Delta 10% Cd

The dual-mode rear spoiler in reminiscent of the original Tesla Model X unit.
At position-1, the spoiler rises at a 23-degree upslope, dropping the car from Cd 0.2666, to Cd 0.24.
At 170 km/h the spoiler increases it's 'rake' to 31.5-degrees for direct downforce, taking a drag hit from the induced drag.
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Holding a protractor up to a large, side-elevation photo of the car yields a 24-degree tangent angle at the upper body's trailing edge. Regulation golf balls are in full separation at 25-degrees tangent angle.
A true-length image with the spoiler at #1 position will allow the EBLA measurement at drag minimum.




https://www.google.com/search?q=NIO+...QJDj66t34,st:0



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Last edited by MetroMPG; 01-20-2024 at 03:26 PM.. Reason: (added video link)
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Old 01-20-2024, 03:27 PM   #2 (permalink)
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Tesla Model Y - ish in profile.



Which also has an active rear spoiler, if I recall?
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Old 01-22-2024, 01:27 PM   #3 (permalink)
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' ish'

Quote:
Originally Posted by MetroMPG View Post
Tesla Model Y - ish in profile.



Which also has an active rear spoiler, if I recall?
Definitely!
I looked at the upcoming 2025 Porsche Macan EV in MOTORTREND, and thought I 'WAS' looking at a TESLA.
I don't know how much of Rob Palin's aerodynamics were incorporated by Franz Von Holzhausen into the Tesla's, but seems like they're plenty good enough for others to riff after.
'Tribute' studios?
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Last edited by aerohead; 01-22-2024 at 01:27 PM.. Reason: typo
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Old 01-23-2024, 04:19 PM   #4 (permalink)
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So flat horizontal spoiler, low drag. Up spoiler, more downforce
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Old 01-25-2024, 12:14 PM   #5 (permalink)
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' flat vs up '

Quote:
Originally Posted by Phase View Post
So flat horizontal spoiler, low drag. Up spoiler, more downforce
I've never seen a definitive research published, in which a 'flat' rear spoiler was shown to be of superior performance to an 'angled' spoiler, as far as low drag was concerned.
Perhaps someone will do that sometime.
As far as I know, as long as the tearing edge of the spoiler is positioned at the 'reversal point', where the boundary-layer has reattached, and pressure recovery resumed, we're essentially 'done' with the streamlining portion.
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If the tearing edge is then pushed further upwards, the streamlines will be over-constricted, more closely-spaced, increasing their velocity, lowering the static pressure, creating a larger wake, of lower base pressure, increasing pressure drag, increasing total drag, exactly the opposite of the kind of 'aerodynamics' Dr. Hucho sought to teach us about.
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And a challenge for us is, recognizing 'false attachment' of downwash when we experience it, compared to actual attached flow.
Tuft testing can easily deceive the experimenter, and pressure readings are meaningless without some reference to a 'target' pressure profile known to be associated with the streamline flow of minimum drag.
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Old 01-27-2024, 12:29 AM   #6 (permalink)
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Quote:
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So flat horizontal spoiler, low drag. Up spoiler, more downforce
I don't disagree but,
A "flat horizontal spoiler" is a classic oxymoron?
Kinda of like using a flat horizontal panel as an air brake?
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Old 01-27-2024, 04:38 AM   #7 (permalink)
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IOW a Bonneville spoiler.
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Old 01-27-2024, 11:51 AM   #8 (permalink)
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' flat panel air-brake '

As the flat panel has Cd 1.15, by angling them up, as Mercedes-Benz did in the 1950s with one of their Grand Prix racing cars, they can make a fine air-brake entering chicanes.
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Old 01-27-2024, 02:34 PM   #9 (permalink)
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Le Mans 1955.

https://www.sae.org/publications: The Role of Aerodynamics in the 1955 Le Mans Crash

For $37 they will speculate on whether the air brake was culpable for 16 pages.
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Old 01-29-2024, 11:27 AM   #10 (permalink)
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'crash'

Quote:
Originally Posted by freebeard View Post
Le Mans 1955.

https://www.sae.org/publications: The Role of Aerodynamics in the 1955 Le Mans Crash

For $37 they will speculate on whether the air brake was culpable for 16 pages.
It's interesting, in that, Daimler had had access to the FKFS next door to them since 1935 when it opened, and I have images of their 1950s GP car in the FKFS wind tunnel, so we know they had the opportunity to fully-wind-tunnel-test the air-brake before ever heading over the border into France.
The SAE abstract ( which are usually free ) might have enough data to answer some questions. I'll be keeping my $37 for something else.

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