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Old 02-27-2024, 10:54 PM   #821 (permalink)
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Looks like a small recirculation pool abaft the crease at it's bottom.

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Old 02-29-2024, 10:58 AM   #822 (permalink)
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' diffuser, skirts,.......................'

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Originally Posted by Phase View Post
Well I know the shape isnít ideal. I was just building a version without a diffuser. I canít put my rear wheel skirts on till I get my all season tires back on. My snow tires are too thick and the wheeel skirts donít fit on. The eqxx and all these low drag Chinese cars donít use wheel skirts though so they canít be THAT important. From my understanding, the roofline is the most important of any of the 4 sides. I was just wondering what the 3 sided boat tail provided versus a proper full one.
* I gave you a 'glimpse' of a diffuser-less tail, and it's ramifications above, at 5). And Lawrence Livermore's tail sides were 'rigid' enough to 'hold' their geometry without deforming aero-elastically under load.
* As you continue your aerodynamic journey, you may come to reverse what it is you believe about the value of wheel skirts. All those Chinese cars are 'Paris Dressmaker' cars, not 'aerodynamic' cars, as is the Vision EQXX. When Daimler-Mercedes Cars gets serious about drag, you'll see them revisit their 1978 C-111- III technology. 'Skirts' are a component of 'wheel integration' and truly low-drag cannot exists without them.
* If a roofline is used solely for pressure recovery/drag reduction, it loses about 60% of it's potential, so, it's 'conditional.' You can see how crappy they are from Fachsenfeld's 1935 research in Stuttgart.
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Old 02-29-2024, 11:17 AM   #823 (permalink)
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Quote:
Originally Posted by aerohead View Post
* I gave you a 'glimpse' of a diffuser-less tail, and it's ramifications above, at 5). And Lawrence Livermore's tail sides were 'rigid' enough to 'hold' their geometry without deforming aero-elastically under load.
* As you continue your aerodynamic journey, you may come to reverse what it is you believe about the value of wheel skirts. All those Chinese cars are 'Paris Dressmaker' cars, not 'aerodynamic' cars, as is the Vision EQXX. When Daimler-Mercedes Cars gets serious about drag, you'll see them revisit their 1978 C-111- III technology. 'Skirts' are a component of 'wheel integration' and truly low-drag cannot exists without them.
* If a roofline is used solely for pressure recovery/drag reduction, it loses about 60% of it's potential, so, it's 'conditional.' You can see how crappy they are from Fachsenfeld's 1935 research in Stuttgart.
Well a cd of .17 and having no skirts and looking good is definitely a great engineering feat. You canít deny how impressive the eqxx vision is

Light year zero said their skirts only add about 7 miles of range to a full battery. Thatís barely anything. What are your thoughts on that? Donít you think it should have a bigger impact?

And Iím not against wheel skirts. I use them when they can fit with my all season tires. I love the look of them and people ask questions and it gets attention in a good way with my Ioniq. It helps feed clean air to my cavity fins in the back too which makes them more effective. But they only seem to add about 1 extra mpg in the real world. Better than nothing, but a lot of effort to build and materials cost for a small gain is a bummer
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Old 02-29-2024, 12:11 PM   #824 (permalink)
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' Cd 0.1716............................................ ......'

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Originally Posted by Phase View Post
Well a cd of .17 and having no skirts and looking good is definitely a great engineering feat. You canít deny how impressive the eqxx vision is

Light year zero said their skirts only add about 7 miles of range to a full battery. Thatís barely anything. What are your thoughts on that? Donít you think it should have a bigger impact?

And Iím not against wheel skirts. I use them when they can fit with my all season tires. I love the look of them and people ask questions and it gets attention in a good way with my Ioniq. It helps feed clean air to my cavity fins in the back too which makes them more effective. But they only seem to add about 1 extra mpg in the real world. Better than nothing, but a lot of effort to build and materials cost for a small gain is a bummer
The Vision EQXX is 'illegal', currently not fit for production in it's present state, due to it's A-pillars and mirrors. In order to bring the car into regulatory compliance would require sacrificing some of it's Cd 0.1716.
M-B had Cd 0.18, 27-years ago with their C-Class-sized F300 concept, so, NO, I'm not impressed. I am 'pleased' that they're willing to have a public conversation about 'aerodynamics.
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Lightyear has half-skirts.
One might imagine it's range with GM's 1987 Aero 2003A's full-skirt package, front and rear, and Cd 0.13.
Other than for air conditioning, it would have no need of a radiator inlet, as IZUZU Glider and Vision EQXX.
And as to Lightyear's 15 km rating, under what actual circumstances does that metric stand? How would I be required to drive that car in order to realize that value, and does it have anything at all to do with how I might choose to drive it? I don't drive on dynamometers. Your question is extremely contextual. Give me the context, and I'll try to be specific.
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As to your '1-mpg', it would only mean something to me if I actually knew what you had done to the car. Nothing can be discerned from your photographs. The FBI and CIA have software which could tease out dimensions from orthogonal projections, but I've no access to technology like that.
You've yet to build a tail. You have no 'advance-knowledge' ( a priori ) as to how it might perform, one way, or another. Skirts, no skirts.
The experts say to include them.
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Old 03-01-2024, 02:24 PM   #825 (permalink)
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Quote:
Originally Posted by aerohead View Post
The Vision EQXX is 'illegal', currently not fit for production in it's present state, due to it's A-pillars and mirrors. In order to bring the car into regulatory compliance would require sacrificing some of it's Cd 0.1716.
M-B had Cd 0.18, 27-years ago with their C-Class-sized F300 concept, so, NO, I'm not impressed. I am 'pleased' that they're willing to have a public conversation about 'aerodynamics.
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Lightyear has half-skirts.
One might imagine it's range with GM's 1987 Aero 2003A's full-skirt package, front and rear, and Cd 0.13.
Other than for air conditioning, it would have no need of a radiator inlet, as IZUZU Glider and Vision EQXX.
And as to Lightyear's 15 km rating, under what actual circumstances does that metric stand? How would I be required to drive that car in order to realize that value, and does it have anything at all to do with how I might choose to drive it? I don't drive on dynamometers. Your question is extremely contextual. Give me the context, and I'll try to be specific.
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As to your '1-mpg', it would only mean something to me if I actually knew what you had done to the car. Nothing can be discerned from your photographs. The FBI and CIA have software which could tease out dimensions from orthogonal projections, but I've no access to technology like that.
You've yet to build a tail. You have no 'advance-knowledge' ( a priori ) as to how it might perform, one way, or another. Skirts, no skirts.
The experts say to include them.
Building a tail for the Ioniq is out of the picture with 200,000 miles on it already. Iíve just been playing with the idea. When I get the new awd drive 2024 Prius, I will be 100 percent building a removable trail hitch boat tail that looks nice and professional so I can recoup the gasoline costs

Iím saying that without any other mods, wheel covers versus no wheel covers is about only 1mpg difference. Granted thatís over 10 miles of extra range which could make a difference in what gas station I can make it to for cheaper gas on a road trip or not. The wheel skirts at this point when on just give a personal style to the car, and gets attention and people asking questions about aerodynamics in parking lots. It helps my Ioniq not look like every other Ioniq here in Portland.

With the rear cavity fins on though, the rear wheel skirts may amply how affective they are. So I may have to do another before and after with the skirts on since they feed clear air to those
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Old 03-01-2024, 02:26 PM   #826 (permalink)
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First time taking cavity fins into the snow finally after this whole season! Interesting snow deposits and low pressure zones behind
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Old 03-02-2024, 08:44 AM   #827 (permalink)
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Any suprises from the snow?
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Old 03-02-2024, 01:58 PM   #828 (permalink)
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Nope. Gas mileage was terrible the whole round trip due to crazy bad rolling resistance in snow and especially slush

I got my winter tires taken off yesterday and my low rolling resistance ecopias on again. Huge difference for mpg. I then put on my rear wheel skirts. Car looks nice and gets attention again now

A route I’ve been doing the last month with winter tires was getting me 58 mpg average. 61 on the best driest warmest days. Yesterday was slightly wet and cold and the same route got me 66 mpg. Would’ve been even more if drier and warmer weather

Then at night in the active rain with wheel covers it seemed to boost same route again but about 2 more mpg. Too many weather variables. But it seems like for speeds under 55 and with mixed city driving the low rolling resistance tires and wheel skirts boost almost 10 extra mpg.
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Old 03-05-2024, 02:18 PM   #829 (permalink)
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How bad is the added frontal area of the fender skirts affecting things?
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Old 03-07-2024, 10:29 AM   #830 (permalink)
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'rear skirts' aero penalty'

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Originally Posted by Phase View Post
How bad is the added frontal area of the fender skirts affecting things?
* Measuring, and scaling from an IONIQ blueprint, the width of the car at the rear wheel arch location is approximately 48.3mm narrower than at it's maximum cross-section width of 1821mm( ignoring the side mirrors ).
* Which gives a 24.15mm narrowing of the body on each side. Nearly an inch.
* Best I can tell from the drawing is that, your added skirt frontal area essentially remains within the 'optical' shadow of the car, and doesn't actually increase projected frontal area, as defined by industry standards.
* If you had a means to align a pocket laser along the centerline of the car, and then move it transversely, maintaining a 'perfectly-parallel' light path, out to the outer 'edge' of the body, and down the sides; you'd be able to determine whether or not the skirts were actually projecting beyond the original 'footprint' .
* A bridge fiducial used in the design studio would tell the tale, as well as Hyundai's CAD-CAM data cloud.

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