Hyundai Kona electric dust deposition
 

Kona electric = 0.29 Cd. Unusual to get an electric car on my local dusty roads.

https://i.postimg.cc/mgQJwzQ4/IMG-1163.jpg

There's a mixture of dust deposited by low aero pressures and heavier mud flicked up by wheels. Looks to me like there is some separation ahead of the flared rear wheel arch. Very good attachment, though, behind the rear wheel as far as the separation edge - except right down the bottom.

https://i.postimg.cc/mgJ3t8c2/IMG-1169.jpg

The back looks very good. Top separation edge (roof extension) working perfectly, side of hatch extensions (complete with vortex generators) again working well, hard to tell how well the upper light and immediately below it is working, and then lower sep edge again working well.

Just by observing their cars, I do think Hyundai / Kia are right at the leading edge of this stuff - but no tech papers as far as I know.

Skip to 1:11

https://www.youtube.com/watch?v=sVU1...ature=youtu.be

How to wash it off, I don't know.

I would argue Mercedes Benz is the manufacturer who is leading in therms of aerodynamics, and that has been the case for a long time.
A CD of 0.29 isn't exactly something to be proud of these days, especialy since it's an electric car that can have a perfectly flat undertray as there isn't an exaust in the way.
Keep in mind, the Audi 100 (C3) had a CD of 0.30 40 years ago.
Meanwhile the Mercedes W213 has a CD of 0.23 and we have a thread about a new one that reaches 0.20.
But still, dust makes for great visualisation.

0.29 is actually pretty good for a lower cost squareback! It’s not fair to compare that with a very expensive sedan - much easier to get low drag with a sedan shape and lots of dollars.

lower cost
 

A generation back, three flavors of the Mitsubishi Mirage 5-door had Cd 0.27. Mitsubishi took advantage of the greenhouse length, lost on many other vehicles of higher drag.
It's an A segment minicar, but it's shape would scale all the way up.

Well, they could have picked a more efficient shape for that car.

I'll let someone with Photoshop skills upsize a Mitsubishi Mirage into a CUV with appropriate ground clearance. I'd think it would look pretty weird - but maybe not.

On that logic every car could be down at Cd=0.2. Obviously, car makers have more aims than just a low Cd.

But we seem to have got side-tracked. If you look under current Hyundai / Kia models you'll soon see that they are right up there with the best - eg very similar to current Audi undersides.

Yeah, I've tried using it. In the real world, it's hard to get the viscosity right. Too viscous and it doesn't move, not viscous enough and it just follows gravity.

I'm trying a few aero mods on this Kona EV
- bluedrive side badge removal
- hood front gap with a seal inside
- wheel trim gaps covered with tape
- wheel spoilers size increased with tape

I would like to remove the roof rails but it's not reversible and the plastic covers are not sold on european websites, only US ...
Search for "kona limited roof rail removal" to see pictures
(can't post a link yet)

I also removed the subwoofer which is too strong and weights 4kg

https://i14.servimg.com/u/f14/18/59/41/51/img_2011.jpg
rear
https://i14.servimg.com/u/f14/18/59/41/51/img_2012.jpg
front
https://i14.servimg.com/u/f14/18/59/41/51/img_2010.jpg

https://i14.servimg.com/u/f14/18/59/41/51/img_2013.jpg
https://i14.servimg.com/u/f14/18/59/41/51/img_2014.jpg

'front gap seal'
 

Be sure that Hyundai didn't intentionally 'engineer' the gaps to provide cooling- air to electronic heat-sinks behind those areas.
You'll be looking for anything attached to a raised, ribbed-aluminum structure, supporting a 'black-box', with a wire loom attached.
Power devices contain switching transistors and diodes which must expel heat in order survive.$$$$$$$$$$$$$$$$$$$$$$$ :eek:

all electronic is watercooled and use the front radiator
I only sealed a 1cm panel gap at the front edge of the hood

https://i14.servimg.com/u/f14/18/59/41/51/kona10.jpg

Maybe it's not even worth to remove the roof rails. Do they provide a similar effect to the winglets on modern aircraft?

Rails are only negative according to what I heard, especially with a side wind which occurs the majority of the drives
On this forum, roof rack are studied, bars from side to side, but I didn't find a topic about rails from front to rear

Larger wheel deflectors actually increase drag. Bigger doesn’t mean better.

https://aia.springeropen.com/article...74-021-00086-7

2021 study shows that bigger deflectors reduce wheel drag, but the INCREASE overall vehicle drag.

I'll have to reread this after I've eaten, but it looks like what works at high speed doesn't work at lower speeds.

But ejecting engine bay air ahead of the wheels sounds interesting Porshe-like.

there are several studies on the injecting air jets now. could be a future thing used in cars later on

https://iopscience.iop.org/article/1...4/7/072005/pdf

This study shows that the angled and slopes wheel deflectors work much better than the straight flat ones most cars use. Think XL1 and light year one/zero car or the front deflectors of a Tesla or Porsche taycan.

Also it looks like “ shutter wheel covers” would be a thing of the future. Like auto grill shutters. The wheels would be fully closed but if they need brake cooling, the shutters will open some gaps in the wheels. Very interesting.

It seems like they could divert cooling air from something that isn't madly rotating.

Thanks for the remarks
On the 1st paper from Phase
it's not only bigger doesn't matter, it's even no deflector at all!
the reference [17] which can be downloaded with scihub, assumed that with a less aero shape of the car and higher clearance, deflector can be usefull
in the article, the comparison is only with and without deflector, but it doesn't say if a bigger deflector would be be better. The size may have been limited for design reason: too big, too ugly

On the 2nd article from Phase
increasing size is said to work but not too big. Study is with angular shape, and enclosed wheel

In the end, I probably made my deflector too big, I will cut some of the rigid tape :)

I was thinking of doing the same thing this week with making my deflectors bigger but came across those recent studies so I decided to chime in. I think I’m going to just added a sloped deflector ramp that goes into the factory OEM deflector at the same height. I’m assuming the engineers in the wind tunnel found the optimal height for each car. The longer ramp obviously can cause clearance issues and look worse on the dealers lot so that’s why they aren’t used

'rails'
 

Members who've been able to easily remove the rails and seal the openings have done so.
When removing the headliner is required to access the attachment hardware, most owners just 'live' with the rails.
To date, I know of no research which has actually quantified any drag, or crosswind effect attributed to just the rails, sans crossmembers.

'wheel shutters'
 

Ford had an F-150 'Atlas' concept truck with battery-powered wheel shutters.
And Mercedes-Benz had dynamic 'morphing' wheels on their 2016 M-B IAA Cd 0.19 concept.
For their M-B EQXX, they just went to camouflaged 'MOONs.'