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Old 04-25-2022, 02:36 PM   #201 (permalink)
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curved diffusers

There's a paucity of official data, for the specific vehicles which employed them.
Vehicles known for exceptionally low drag might offer insight into diffuser design 'solutions' which bore fruit.

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Old 04-25-2022, 04:20 PM   #202 (permalink)
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In the midst of the paucity, and given the aspect ratio of the width and height of the plenum; a flat roof with flared skegs seems worth considering.

My example is the Bonnevette:

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Old 04-25-2022, 09:39 PM   #203 (permalink)
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Quote:
Originally Posted by aerohead View Post
I can't address the videos. Unless the rules have changed.
I tried to give you insights into the mind of someone who witnessed low drag firsthand. Hucho's Cd 0.15 'template' of 1978 didn't have a diffuser.
Volkswagen's lowest drag, Cd 0.14 'Flow-body' of 1981 had a 'slow' diffuser.
I have tuft-testing images of a 'steep' Lamborghini diffuser experiencing 100% counter-flow. There IS an angle at which air behind the car begins to flow forwards down under the car, not visa-versa.
There may be caveats attached to specific designs that you'd want/need to know about.
Volvo and Polestar aren't necessary known for low drag.
'High-performance' cars will pay a drag penalty for high speed stability.
what about tesla model s plaid? its high performance and the CD is 0.20 and low drag. look at its rear diffuser

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Old 04-25-2022, 09:41 PM   #204 (permalink)
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Quote:
Originally Posted by freebeard View Post
In the midst of the paucity, and given the aspect ratio of the width and height of the plenum; a flat roof with flared skegs seems worth considering.

My example is the Bonnevette:

that looks similar to the ioniq spoiler, but obviously much longer. attached air flow down the rear windshield then flat straight out spoiler. can you explain out that also helps? i thought the main idea was to reduce wake size like in the xl1 and light year one designs
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Old 04-25-2022, 11:30 PM   #205 (permalink)
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I'd posted that for the difusser, but for the spoiler go to the five pages here: ecomodder.com/forum/showthread.php/flat-bonneville-type-spoiler. It provides a surface for any vortexes to reattach to.

Beyond that IIRC someone said the side plates are what they are because the rules dictate a maximum length and height. They just maxed it out and rounded the corners.

A Studebaker



Rooftop fences and the skegs appear to flare somewhat (maybe not).
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Old 04-26-2022, 02:05 AM   #206 (permalink)
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Quote:
Originally Posted by freebeard View Post
I'd posted that for the difusser, but for the spoiler go to the five pages here: ecomodder.com/forum/showthread.php/flat-bonneville-type-spoiler. It provides a surface for any vortexes to reattach to.

Beyond that IIRC someone said the side plates are what they are because the rules dictate a maximum length and height. They just maxed it out and rounded the corners.

A Studebaker



Rooftop fences and the skegs appear to flare somewhat (maybe not).
so pretty much extend the rear spoiler and have it slightly curve down and out? thoughts on the rear of the new sonata? it has a out and down curved box cavity spoiler and mini VGs on the edges. it has the same CD as the ioniq apparently

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Old 04-26-2022, 12:27 PM   #207 (permalink)
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thoughts on the rear of the new sonata?
Need more coffee.

If you look at the continuous loft line from the top of the roof to the rear bumper, the spoiler is a wickerbill.
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Old 04-26-2022, 08:38 PM   #208 (permalink)
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Electric Porsche taycan rear diffuser. Curved and pretty steep
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Old 04-26-2022, 09:17 PM   #209 (permalink)
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It's a logarithmic curve. A different example:

The upper extent isn't adding much.

The ultimate example is the Maclaren T50

www.slashgear.com/gordon-murray-automotive-t50-supercar-ground-effect-fancar-revealed-10602788

It's so steep there is probably recirculation in the top. Until the fan cuts in and pulls the airflow up.
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Old 04-26-2022, 09:54 PM   #210 (permalink)
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how do you embed an image being uploaded from a hard drive file location? i have only been able to do it with web URL addresses

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