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Old 05-16-2022, 01:00 PM   #291 (permalink)
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IONIQ belly and skirts

Just for ----- and giggles, if the IONIQ reacted to underbody paneling at all like the Audi 100-III, the 'missing' panels and 'slow' diffuser might represent a delta-Cd 0.030.
If rear skirts returned a 1.89% delta Cd as they did for WS 12 Aero, Advantage West Midlands, UK, Audi test car, that would be another delta-Cd 0.005.
That would put the IONIQ in Cd 0.205 territory.
It wouldn't take much else to push it to the new Cd 0.20 target.

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Old 05-16-2022, 01:10 PM   #292 (permalink)
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duckduckgo.com/?q=US+Patent+8590961%2C+February+21%2C+2012&ia=web

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https://ecomodder.com › forum › showthread.php › eco-modding-tahoe-hybrid-40mpg-goal-38117-2.html
Eco modding the Tahoe Hybrid 40MPG Goal.. - Page 2 - Fuel Economy ...
This boat tail shows up on US Patent,8590961,February 21,2012,by Thomas Scott Breidenbach.It's a variation on a variation of the Ahmed Body boat-tail, both in Huchos' textbook. With rear wheel skirts,this modification would probably satisfy your load reduction requirement for the CVT mode.
Aha, the Ahmed Body.
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Old 05-16-2022, 01:20 PM   #293 (permalink)
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Quote:
Originally Posted by aerohead View Post
Just for ----- and giggles, if the IONIQ reacted to underbody paneling at all like the Audi 100-III, the 'missing' panels and 'slow' diffuser might represent a delta-Cd 0.030.
If rear skirts returned a 1.89% delta Cd as they did for WS 12 Aero, Advantage West Midlands, UK, Audi test car, that would be another delta-Cd 0.005.
That would put the IONIQ in Cd 0.205 territory.
It wouldn't take much else to push it to the new Cd 0.20 target.
I mean Iím removing side mirrors so that would put that at 19 right there give or take

I looked at the bottom of my Ioniq again though, sure itís not perfectly smooth, but itís extremely straight and none of the part under the car buldge out to disrupt airflow. I think Hyundai did the best they could with aligning the muffler and everything underneath to be extremely flush without covering it with a panel. Even the muffler thatís laying horizontally is angle slightly like a rear diffuser to guide the air. Obviously it can be improved.

If smooth under body and rear skirts/spats can put it at 20, then no mirrors 19, I wonder what the hypothetical cd could be with an extended spoiler and mini box cavity in the rear. Then duct tape the door handles smooth and use racing tape to cover every body panel crack 😂
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Old 05-16-2022, 01:56 PM   #294 (permalink)
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Cd 0.19

Quote:
Originally Posted by Phase View Post
I mean Iím removing side mirrors so that would put that at 19 right there give or take

I looked at the bottom of my Ioniq again though, sure itís not perfectly smooth, but itís extremely straight and none of the part under the car buldge out to disrupt airflow. I think Hyundai did the best they could with aligning the muffler and everything underneath to be extremely flush without covering it with a panel. Even the muffler thatís laying horizontally is angle slightly like a rear diffuser to guide the air. Obviously it can be improved.

If smooth under body and rear skirts/spats can put it at 20, then no mirrors 19, I wonder what the hypothetical cd could be with an extended spoiler and mini box cavity in the rear. Then duct tape the door handles smooth and use racing tape to cover every body panel crack 😂
1) Decades-old mirrors would ( have been reported at ) delta-Cd 0.015. Giving you Cd 0.225.
2) TESLA-quality mirrors would be delta-Cd 0.010, giving you Cd 0.23.
--------------------------------------------------------------------------------------
' With a long diffuser, a notable reduction in drag can be achieved with a very small angle... However, this effect is only assured with a very smooth underside.' Dr.-Ing. Wolf Heinrich Hucho, 2nd-Edition, page-144
3) No belly-pan, no diffuser, and lose 30-counts.
--------------------------------------------------------------------------------------
Belly pan with diffuser, rear skirts, and mirror delete: Cd 0.19-to- Cd 0.195.
-------------------------------------------------------------------------------------
The 2012 Coventry University testing of the Audi A2 box-cavity showed a 2% delta Cd, from a car with Cd 0.288.
2% from a Cd 0.24 car would be 0.0048, yielding Cd 0.1852-to- Cd 0.1902
------------------------------------------------------------------------------------
I taped all the seams on SPIRIT and it showed zero difference in the wind tunnel. General Motors allowed 0.007 for these 'features'.
-------------------------------------------------------------------------------------
' Qualitatively, the effect of the length upon the aerodynamic drag is similar to that for the ( streamline ) body of rotation.' W.H. Hucho, 2nd-Ed., pg 142
-------------------------------------------------------------------------------------
' the drag reduction from an elongated tail varies almost linearly with the reduction in cross section area.' Jeff Howell et al.,' Streamlined Tails- The Effects of Truncation on Aerodynamic Drag,' Loughborough University, 2020, Abstract, SAE Paper 2020-01-0673
--------------------------------------------------------------------------------------
' base pressure also depends upon the angle at which the flow separates from the contour.' W.H. Hucho, 2nd-Ed, page- 141
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Old 05-16-2022, 02:01 PM   #295 (permalink)
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Quote:
Originally Posted by aerohead View Post
1) Decades-old mirrors would ( have been reported at ) delta-Cd 0.015. Giving you Cd 0.225.
2) TESLA-quality mirrors would be delta-Cd 0.010, giving you Cd 0.23.
--------------------------------------------------------------------------------------
' With a long diffuser, a notable reduction in drag can be achieved with a very small angle... However, this effect is only assured with a very smooth underside.' Dr.-Ing. Wolf Heinrich Hucho, 2nd-Edition, page-144
3) No belly-pan, no diffuser, and lose 30-counts.
--------------------------------------------------------------------------------------
Belly pan with diffuser, rear skirts, and mirror delete: Cd 0.19-to- Cd 0.195.
-------------------------------------------------------------------------------------
The 2012 Coventry University testing of the Audi A2 box-cavity showed a 2% delta Cd, from a car with Cd 0.288.
2% from a Cd 0.24 car would be 0.0048, yielding Cd 0.1852-to- Cd 0.1902
------------------------------------------------------------------------------------
I taped all the seams on SPIRIT and it showed zero difference in the wind tunnel. General Motors allowed 0.007 for these 'features'.
-------------------------------------------------------------------------------------
' Qualitatively, the effect of the length upon the aerodynamic drag is similar to that for the ( streamline ) body of rotation.' W.H. Hucho, 2nd-Ed., pg 142
-------------------------------------------------------------------------------------
' the drag reduction from an elongated tail varies almost linearly with the reduction in cross section area.' Jeff Howell et al.,' Streamlined Tails- The Effects of Truncation on Aerodynamic Drag,' Loughborough University, 2020, Abstract, SAE Paper 2020-01-0673
--------------------------------------------------------------------------------------
' base pressure also depends upon the angle at which the flow separates from the contour.' W.H. Hucho, 2nd-Ed, page- 141
I wonder how much wiper blade delete affects drag. Lots of people do it for racing or hypermiling.

Wonder what my highway mpg at 59 EPA rating would be by dropping the drag from 24 down to cd 19. Seems realistic.

I wish I could shave weight in the car for city driving, but removing rear seats or changing front seats to light weight racing seats seems like it wouldnít even make much of a difference.
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Old 05-16-2022, 02:35 PM   #296 (permalink)
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wiper delete...............

Quote:
Originally Posted by Phase View Post
I wonder how much wiper blade delete affects drag. Lots of people do it for racing or hypermiling.

Wonder what my highway mpg at 59 EPA rating would be by dropping the drag from 24 down to cd 19. Seems realistic.

I wish I could shave weight in the car for city driving, but removing rear seats or changing front seats to light weight racing seats seems like it wouldn’t even make much of a difference.
A small bubble of stagnant air at the cowl area below the base of the windshield is an intentional design feature which, allows un-powered, passive cabin ventilation.
Typically, the windshield wipers reside within this 'bubble' and the outer airflow just travels over it, rendering virtually zero drag for the wipers.
A Lamborghini Aventador, at 210-mph is a different story.
-------------------------------------------------------------------------------------
The EPA HWY numbers might be seen around 100-km/h ( 62-mph ).
You might knock the barnacles off your calculator and see if you can run the numbers. The sooner you learn to 'fish', the sooner you can throw me under the bus. You'll be self-sufficient in quanta.
As to 'CITY' driving, see if the pure electric Hyundai's use a lower rolling resistance tire. I know GM does this. It's very difficult to remove enough weight from modern cars to make a difference.
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Last edited by aerohead; 05-16-2022 at 02:40 PM.. Reason: add data
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Old 05-16-2022, 02:46 PM   #297 (permalink)
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Quote:
I wonder how much wiper blade delete affects drag. Lots of people do it for racing or hypermiling.
I did it on the Dasher and Superbeetle to reduce replacement cost.
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Old 05-16-2022, 05:46 PM   #298 (permalink)
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Quote:
Originally Posted by aerohead View Post
A small bubble of stagnant air at the cowl area below the base of the windshield is an intentional design feature which, allows un-powered, passive cabin ventilation.
Typically, the windshield wipers reside within this 'bubble' and the outer airflow just travels over it, rendering virtually zero drag for the wipers.
A Lamborghini Aventador, at 210-mph is a different story.
-------------------------------------------------------------------------------------
The EPA HWY numbers might be seen around 100-km/h ( 62-mph ).
You might knock the barnacles off your calculator and see if you can run the numbers. The sooner you learn to 'fish', the sooner you can throw me under the bus. You'll be self-sufficient in quanta.
As to 'CITY' driving, see if the pure electric Hyundai's use a lower rolling resistance tire. I know GM does this. It's very difficult to remove enough weight from modern cars to make a difference.
Iíve always been curious to what the cd for the electric Ioniq is. It has a smooth underbody versus the hybrids obviously. Not to mention a much smoother front grill. I wonder if the hybrid Ioniqs are actually 25 and the electric version is 24. Or maybe the hybrids are 24 and the electric is 23 or lower. Then again, if it was lower, Hyundai would probably be shouting out how much lower the ev isÖ

No idea.
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Old 05-16-2022, 06:07 PM   #299 (permalink)
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IONIQ Cds

Quote:
Originally Posted by Phase View Post
Iíve always been curious to what the cd for the electric Ioniq is. It has a smooth underbody versus the hybrids obviously. Not to mention a much smoother front grill. I wonder if the hybrid Ioniqs are actually 25 and the electric version is 24. Or maybe the hybrids are 24 and the electric is 23 or lower. Then again, if it was lower, Hyundai would probably be shouting out how much lower the ev isÖ

No idea.
I've no idea. Perhaps we'll have access to those before too long. If Hyundai/KIA/Genesis publishes a technical paper it will show up at SAE International at some point.
Vehicle range will be an artifact of Cd to some degree. It's funny how many automotive journalists haven't made the connection between CdA and range yet.
They're bored with TESLA's 'look', and want different 'styling,' not realizing that Tesla's 'appearance' is a critical key to highway range.
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Old 05-16-2022, 07:11 PM   #300 (permalink)
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Quote:
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Wonder what my highway mpg at 59 EPA rating would be by dropping the drag from 24 down to cd 19. Seems realistic.
Using the coefficients that matched the MPG vs speed from clean mpg I come up with:



MPH Est MPG stock Est MPG -0.05Cd
5 31.83 31.85
10 55.6 55.78
15 72.47 73.16
20 83.12 84.75
25 88.37 91.28
30 89.28 93.62
35 87.03 92.74
40 82.73 89.59
41 81.71 88.76
42 80.65 87.88
43 79.56 86.95
44 78.44 85.99
45 77.3 84.99
46 76.14 83.96
47 74.97 82.9
48 73.78 81.82
49 72.59 80.72
50 71.4 79.61
51 70.2 78.49
52 69.01 77.35
53 67.82 76.21
54 66.64 75.07
55 65.46 73.93
56 64.3 72.78
57 63.15 71.64
58 62.01 70.51
59 60.88 69.38
60 59.77 68.26
61 58.67 67.15
62 57.6 66.05
63 56.53 64.96
64 55.49 63.88
65 54.46 62.81
70 49.6 57.7
75 45.19 52.97
80 41.23 48.65
85 37.68 44.72
90 34.51 41.16
95 31.67 37.94
100 29.14 35.04
105 26.87 32.42
110 24.84 30.06
115 23.01 27.92
120 21.36 25.98
125 19.88 24.23
130 18.54 22.64
135 17.32 21.19
140 16.21 19.86
145 15.21 18.65
150 14.29 17.55
155 13.45 16.53
160 12.68 15.6
165 11.97 14.74
170 11.31 13.95
175 10.71 13.22
180 10.16 12.54
185 9.64 11.92
190 9.17 11.33
195 8.72 10.79
200 8.31 10.29

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