Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 05-20-2019, 06:24 AM   #1 (permalink)
Master EcoModder
 
Joggernot's Avatar
 
Join Date: Jun 2013
Location: Texas
Posts: 449
Thanks: 1,743
Thanked 125 Times in 104 Posts
Roof Spoiler

Saw this on another forum. Looks like it would be worst aerodynamics.

Attached Thumbnails
Click image for larger version

Name:	Roof Spoiler.jpg
Views:	209
Size:	62.0 KB
ID:	25908  
  Reply With Quote
The Following User Says Thank You to Joggernot For This Useful Post:
aerohead (05-22-2019)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 05-20-2019, 09:14 AM   #2 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 4,158
Thanks: 120
Thanked 2,790 Times in 1,959 Posts
It's hard to tell because it all depends on how it fills out or does not fill out the aerodynamic template.

I'm guessing it's this profile below - correct me if I'm wrong.

https://www.nadaguides.com/Cars/2018...0-FWD/Pictures


Guessing where that top of rear window spoiler is, I suspect it is in the airflow and interacting with the attached airflow.

Spoilers spoil the airflow, causing rolling vortexes that can pull down the layer of air above it - a good thing but it takes energy - a bad thing.

I'm not a fan of this upper location because the spoiler is not at a 60 degree angle, the angle required for creating a good vortex.

In effect this spoiler is not a spoiler, it is a flatish plate that allows for a clean release of air, but it's a clean release of air where attachment would normally be, so it's kind of a stupid location.

The effect is a larger hole in the air than without it.

Again, this needs to be verified with a template overlay - go for it Joggernot.
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following 2 Users Say Thank You to kach22i For This Useful Post:
aerohead (08-26-2020), Joggernot (05-20-2019)
Old 05-20-2019, 06:53 PM   #3 (permalink)
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,049

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 13.74 mpg (US)
Thanks: 43
Thanked 331 Times in 233 Posts
https://youtu.be/Fq8hkPobpes

Take away seems to be “roof spoilers are just stupid”
  Reply With Quote
The Following 3 Users Say Thank You to 2000mc For This Useful Post:
aerohead (08-26-2020), Joggernot (05-21-2019)
Old 05-21-2019, 06:56 AM   #4 (permalink)
Master EcoModder
 
Joggernot's Avatar
 
Join Date: Jun 2013
Location: Texas
Posts: 449
Thanks: 1,743
Thanked 125 Times in 104 Posts
Quote:
Originally Posted by 2000mc View Post
https://youtu.be/Fq8hkPobpes

Take away seems to be “roof spoilers are just stupid”
Excellent views with the hydrogen bubbles to show the effect. I'll attach my effort with the template. Seems clear that the roof spoiler would disrupt the template and create drag.
Attached Thumbnails
Click image for larger version

Name:	Untitled.jpg
Views:	140
Size:	19.3 KB
ID:	25912  
  Reply With Quote
The Following User Says Thank You to Joggernot For This Useful Post:
aerohead (08-26-2020)
Old 05-21-2019, 09:00 AM   #5 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 4,158
Thanks: 120
Thanked 2,790 Times in 1,959 Posts
Quote:
Originally Posted by 2000mc View Post
https://youtu.be/Fq8hkPobpes

Take away seems to be “roof spoilers are just stupid”
Sounds about right, roof spoilers upset the air flow of a clean aerodynamic car, and upsets the air further down the line of less clean cars with a real trunk lid.

I do see room in life for keeping an open mind on this in only a very limited scope pending wind tunnel verification.

1. Historic examples from late 1970's of redirecting roof foils on BMW and Lancia Class-B type race cars with notch-back roof lines.

Example
https://www.scalemates.com/kits/tami...racing--128154


2. Spoilers on notch-back cars that angle down at about a 7-degree angle and give the air a clean edge to release from.

I use words of caution about blind rage or blanket ridicule on any topic as it invites group think over actual analysis, and that's the sort of thing that made these idiot devices popular to begin with.

One last point, none of the spoilers in the video were true +60 degree Gurney flaps that I was talking about earlier as the narrator focused on aftermarket junk. I would be very interested in seeing wind tunnel or CFD diagrams of Wickebill/Gurney flaps on roof edges if anyone finds them.
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following 2 Users Say Thank You to kach22i For This Useful Post:
aerohead (05-22-2019), Joggernot (05-21-2019)
Old 05-21-2019, 09:10 AM   #6 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 4,158
Thanks: 120
Thanked 2,790 Times in 1,959 Posts
Quote:
Originally Posted by Joggernot View Post
Excellent views with the hydrogen bubbles to show the effect. I'll attach my effort with the template. Seems clear that the roof spoiler would disrupt the template and create drag.
The yellow spoiler you drew in might misrepresent the majority of aftermarket roof spoilers. From what I can tell many of them are rather flat 180 degree plane.

However some do angle up a bit at the lip similar to your addition.

I think that some of these roof spoilers are small enough and flat enough as not to cause as much damage as others of more aggressive design.

Meaning one is still shooting one's self, but not a head shot, just shooting one's self in the foot.
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following 2 Users Say Thank You to kach22i For This Useful Post:
aerohead (05-22-2019), Joggernot (05-21-2019)
Old 05-21-2019, 05:59 PM   #7 (permalink)
Moderator
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Urbana, IL
Posts: 1,935

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
SUV
90 day: 51.62 mpg (US)

Tycho the Truck - '91 Toyota Pickup DLX 4WD
90 day: 22.22 mpg (US)
Thanks: 198
Thanked 1,797 Times in 937 Posts
I came across this in a textbook last winter. It seems relevant here.

__________________
UIUC Aerospace Engineering
www.amateuraerodynamics.com
  Reply With Quote
The Following 2 Users Say Thank You to Vman455 For This Useful Post:
aerohead (05-22-2019), Joggernot (05-22-2019)
Old 05-22-2019, 08:47 AM   #8 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 4,158
Thanks: 120
Thanked 2,790 Times in 1,959 Posts
The word "spoiler" is applied to any trailing edge device that's been added on including those of modest negative slope and those of +60 degrees.

In that context just about every SUV and Crossover made today has one, and so do the last of the wagons and hatchbacks.

Just want to point this out for clarity.

https://www.hendrickhondasc.com/used...ZZMCAXGC025606


https://www.grandmotorcars.com/detai...7fbb98380.html



https://www.consumerreports.org/smal...ooper-preview/


It's just not the location at the back of the car that makes the examples above better than the ones in the video. It is their design and angle of attack.
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 05-22-2019 at 08:53 AM..
  Reply With Quote
The Following User Says Thank You to kach22i For This Useful Post:
aerohead (05-22-2019)
Old 05-22-2019, 11:55 AM   #9 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,852
Thanks: 23,907
Thanked 7,199 Times in 4,637 Posts
roof spoiler

Quote:
Originally Posted by Joggernot View Post
Saw this on another forum. Looks like it would be worst aerodynamics.
My first question would be,is this an OEM Hyundai part for the Genesis,or some aftermarket piece?
The Genesis is capable of in the neighborhood of 150-mph.If the car was found to be unstable at this speed,Hyundai may have added it as a palliative,as Audi did with their TT.And Daimler did with their Mercedes-Benz 190 EVO.Mitsubishi Lancer.Subaru WRX.
Car companies don't want their customers killing themselves.It's bad press.
You can legally drive the Genesis at top speed on portions of the Autobahn,so it would be an issue,at least in Europe.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 05-23-2019, 07:13 AM   #10 (permalink)
Master EcoModder
 
Joggernot's Avatar
 
Join Date: Jun 2013
Location: Texas
Posts: 449
Thanks: 1,743
Thanked 125 Times in 104 Posts
The person was very proud of the new after-market add on. Not an OEM piece. Yes, it was on a Hyundai Genesis, but the year wasn't given.

  Reply With Quote
The Following User Says Thank You to Joggernot For This Useful Post:
aerohead (05-25-2019)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com