Pizza pan wheel cover testing

[freebeard]

Drum brakes have backing plates, and don't drag like disks.

[aerohead]

Here's some past published data, just to muddy the waters:
1) for the Cd 0.312, 1982 Pontiac Trans Am Firebird,
* the OEM ventilated convex covers, compared to the naked, welded pressed- steel wheels, reduced drag by delta-Cd 0.021.
* by taping all the openings closed, delta-Cd 0.024.
* with John Shinella's top-secret, convex wheel covers, delta-Cd 0.027.
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2) for the Cd 0.29, 1985 Subaru XT coupe:
* compared to the naked pressed-steel wheels, the ventilated, flat disc covers reduced drag by delta-Cd 0.006.
* by taping all the openings closed, delta-Cd 0.008.
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3) The 2012 Jaguar XJ Supercharged was wind tunnel tested at MIRA, by Coventry University:
* when the OEM, 10-spoke, alloy wheels were covered 100% with flat discs, drag was reduced by 3.3% ( Cd 0.29 - Cd 0.2804 ).
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4) From the 2018, 8th International Conference on Advanced Concepts in Mechanical Engineering, Case-4, a CFD-generated, generic hatchback, of Cd 0.377 was aero-modified with full rear skirts, plus 100% coverage flat wheel covers, covering the 'OEM', 6-spoke wheels, resulting in a delta- Cd 0.024 drag reduction ( 6.36% ) for the two modifications.
* Coventry University had tested the U.S.- spec, Cd 0.288, Audi A2 @ MIRA, with full rear skirts, and measured a delta-Cd 0.038 drag reduction , over 8-spoke wheels ( a 13.19% drag reduction ).
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5) The 1985 Pontiac Trans Am Firebird, with aluminum turbo wheels was Cd 0.32.
With the standard aero wheel covers, Cd 0.29.
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6) In 2012, Coventry University measured an Cd 0.316, Audi A3 @ MIRA, with full rear wheel skirts, and realized a delta-Cd 0.006 drag reduction ( 1.898% ).
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7) The 'spread' for rear wheel skirt delta-Cds between the Audi A2, and 4)'s generic hatch is so great that, it makes parsing out, and isolating, the drag reduction contribution for the wheel covers, with any confidence, too difficult.
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Perhaps a member, or guest, which has access to an 'aero- wheel covered' Model 3 could perform a 'taped' comparison, and report.

[Phase]

Seems like taping the slots on my Ioniq wheel aero discs gives about 1 extra mpg at moderate speeds then based on the Cd reduction

[Piotrsko]

At moderate speeds you could be in an odd transition zone drag wise that could affect total flow. Wouldn't be uncommon.

[aerohead]

Originally Posted by Piotrsko

At moderate speeds you could be in an odd transition zone drag wise that could affect total flow. Wouldn't be uncommon.

Can you address this ' transition zone' comment.
Since 1973, I've never heard, nor read of it, pertaining to road vehicle aerodynamics.
The drag from 'windage'/'ventilation drag' of the rotating wheels will vary continuously with velocity, but that's another matter.

[Phase]

Originally Posted by Piotrsko

At moderate speeds you could be in an odd transition zone drag wise that could affect total flow. Wouldn't be uncommon.

Please explain

And I’ve noticed aero mods still work better at moderate speeds versus high speeds. Everyone says aero mods help at higher speeds because of the load, but they don’t

Say your mod gives a 5 percent improvement in gas mileage

When going 65 mph and getting 70 mpg, that adds an extra 3.5 mpg

When going 85 mph on interstate and getting 40 mpg, it only adds 2 extra mpg

The aero mods compound even more range increases when going at slower highway speeds versus higher highway speeds

A boat tail can make a huge difference at 55 mph like most modders here have shown. But a boat tail full size only would give you a few little mpg points when going 85-90 mph on desert interstates in Idaho and Utah and Montana. So what’s even the point of aero mods for extremely fast driving? They essentially don’t work at high speeds

[freebeard]

"Aerodynamics are for people who can't build engines." -- Enzo Ferrari

[Piotrsko]

Aero mods would work better at higher speeds if you tested them at those speeds, designed them with those speeds in the parameters. That said, some high speed mods would be draggy at lower speeds or even inappropriate.

[bwilson4web]

I wonder if the Cyber Truck wheel covers are air tight?

There appears to be a gap around the rim but I can't tell if it is a by-pass or air leak from the interior of the wheel.

Bob Wilson

[aerohead]

Originally Posted by bwilson4web

I wonder if the Cyber Truck wheel covers are air tight?

There appears to be a gap around the rim but I can't tell if it is a by-pass or air leak from the interior of the wheel.

Bob Wilson

I watched a YouTube about a 'pre-delivery' Cybertruck in which the narrator removed one of the wheel covers by hand, to reveal the 2-pc construction. The outer cap looks like vacuum- thermo-formed ABS. Light and flimsy.
There just wasn't enough resolution or contrast with which to discern whether or not a gap existed.
If there is one, it's a fraction of an inch.
I'm hoping that one will show up in town, giving me an opportunity to scrutinize the whole shebang.