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View Full Version : Aerodynamics : Vortex Generators, Spoilers, etc.



Ash
11-04-2009, 08:56 AM
I was researching Vortex generators (like are on the Mitsubishi Evolution MR) and found this really informative article on Autospeed, then linked to a couple more Aero articles. After reading them, everything kind of clicked. They Explains vehicle aerodynamics and airflow (high pressure/low pressure zones, turbulence, spoiler placement based on rear window slope, etc.) in terms that don't make your eyes gloss over. Also shows a D.I.Y. quasi wind tunnel method called wool-tuft testing that we can all do. A really good read. Post up any ideas, thoughts, or comments.

Blowing the Vortex
------------------
Part 1: http://www.autospeed.com/A_3058/cms/article.html
Part 2: http://www.autospeed.com/A_3059/cms/article.html
Part 3: http://autospeed.com/A_3060/cms/article.html
Part 4: http://autospeed.com/cms/title_Blowing-the-Vortex-Part-4/A_3061/article.html (very interesting results on placing vortex generators below the front bumper...noticeable high speed stability increase)


Aero/Wool-Tuft Testing
------------------------
Part 1: http://www.autospeed.com/A_108656/cms/article.html
Part 2: http://www.autospeed.com/A_108674/cms/article.html
Part 3: http://www.autospeed.com/A_108675/cms/article.html


Undertrays, Spoiler, and Bonnet Vents
-------------------------------------
Part 1: http://www.autospeed.com/A_2159/cms/article.html
Part 2: http://www.autospeed.com/A_2160/cms/article.html
Part 3: http://www.autospeed.com/cms/A_2162/article.html

Roadbuster
11-04-2009, 08:07 PM
Interesting reading, Ash.

Agrees with somethings I have read and seen others use. The high pressure zone at the base of the windshield is one. This is very useful info for those of us building our own spoilers. I like the yarn test!

Jon

Yoda4561
11-04-2009, 09:17 PM
Real interesting read for us aero novices, I'll be bookmarking this for future reference.

garickman
05-07-2010, 03:15 PM
Interesting!!

Bjkadron
05-07-2010, 04:40 PM
Hey all!
I recently learned a new trick for aero testing. Mix Powdered paint with oil and just drip it on. Then go for a drive and see what it looks like.. The long streaks are the low pressure zones. Beats taping a million pieces of yarn all over your car!

novaderrik
05-07-2010, 05:01 PM
i'm gonna get some of those airtabs and start plastering them all over my 97 Cavalier.. they might just be the thing i need to get up to and over the 40mpg mark that i've been chasing for the last 2 years.

Gitter Dun
05-08-2010, 05:58 AM
Very cool thread, I have recently been doing some research on aero for my car. I had thrown on a fiberglass hood a ways back and the hood did not have any structure underneath it to support it. I noticed that when I was at about 65 mph the center of the hood would lift. Well that led me to beleive that with the wind coming through the grill with the steel hood was lifting the front of the car up which is something I noticed on the road course at speeds of 130 mph and up. I have been thinking about designing an aero hood and also how to divert air and limiting air coming through the front grill.

Ash
05-09-2010, 02:18 AM
I'm glad you guys dig it as much as I do, and props to AutoSpeed for the articles. It's so funny how some aspects of this hobby come off as unobtainuim fueled voodoo, and when you boil it down, end up requiring the simplest of tools to understand and implement. Yarn, Tape, Magnehelic gauge, and a manometer...I never would have guessed.

The oil and powdered paint makes a lot of sense, but the nooks and crannies it would get into makes me cringe.

40 MPG. Thats insane.

DocJr
05-09-2010, 11:05 AM
For a good read...

http://www.carstylingmag.com/default.tpl?pageID=1&page=full&cart=127343200218048631&--eqskudatarq=AERODYN

A required book for my Aero class in school.

Bjkadron
05-09-2010, 07:05 PM
I'm glad you guys dig it as much as I do, and props to AutoSpeed for the articles. It's so funny how some aspects of this hobby come off as unobtainuim fueled voodoo, and when you boil it down, end up requiring the simplest of tools to understand and implement. Yarn, Tape, Magnehelic gauge, and a manometer...I never would have guessed.

The oil and powdered paint makes a lot of sense, but the nooks and crannies it would get into makes me cringe.

40 MPG. Thats insane.


Pressure washer. Easy :)

A lot of things are like that *voodoo* or whatnot and actually somewhat simple on the surface...

Bjkadron
05-09-2010, 07:06 PM
For a good read...

http://www.carstylingmag.com/default.tpl?pageID=1&page=full&cart=127343200218048631&--eqskudatarq=AERODYN

A required book for my Aero class in school.

Awesome! Just what I need! Another cool book!

How big is it?

Ash
05-09-2010, 08:53 PM
Awesome! Just what I need! Another cool book!

How big is it?


X2. Ordering on Pay Day

DocJr
05-10-2010, 06:02 PM
Hey guys,

Dimensions are 10.25x9.75x.5 in thick...168 pages. The whole read isn't as big as what it seems, its also written in japanese, but still, by all means, it's an in depth book, with TONS of pictures, diagrams, charts, etc. I'm pretty sure many car designers have read it.

I also have Car Styling's clay sculpting edition. I would love to have the actual magazine subscription, but its 150 bucks a year...for 4 publications!!

Glad I could add to the thread!

Bjkadron
05-10-2010, 06:37 PM
Hey guys,

Dimensions are 10.25x9.75x.5 in thick...168 pages. The whole read isn't as big as what it seems, its also written in japanese, but still, by all means, it's an in depth book, with TONS of pictures, diagrams, charts, etc. I'm pretty sure many car designers have read it.

I also have Car Styling's clay sculpting edition. I would love to have the actual magazine subscription, but its 150 bucks a year...for 4 publications!!

Glad I could add to the thread!

Sweet! I'll start saving.

Gitter Dun
05-10-2010, 07:34 PM
Could be time for an Aerodynamics forum. That would be cool.

Bjkadron
05-11-2010, 02:52 PM
Could be time for an Aerodynamics forum. That would be cool.

Vote 2! :seizure:

sik68
05-12-2010, 10:36 AM
Here's what I have planned aerodynamically:

:twothumbs:

Closeout panel
https://static1.pt-content.com/images/noimg.gif

and hood louvers

:twothumbs:

https://static1.pt-content.com/images/pt/2009/09/11-1.jpg

Bjkadron
05-12-2010, 12:43 PM
Here's what I have planned aerodynamically:

:twothumbs:

Closeout panel
https://static1.pt-content.com/images/noimg.gif

and hood louvers

:twothumbs:


What does it close out? the whole front?

sik68
05-12-2010, 03:29 PM
What does it close out? the whole front?

Check this out:
http://undercoverinnovations.com/Camaro1Lower.htm

Bjkadron
05-12-2010, 06:13 PM
Oh! Ok.. It is just a front undertray. you confused me with the "closeout panel" name.

Rod
05-14-2010, 05:30 PM
Could be time for an Aerodynamics forum. That would be cool.


I agree :cheers:

Yoda4561
05-14-2010, 06:12 PM
I think more discussion on aero stuff would be awesome, but given the limited posts about it I dun think that there will be a forum dedicated any time soon :(

Ash
05-14-2010, 08:52 PM
yeah, I agree Yoda. But maybe "Paint and Body" could be changed to "Paint, Body, & Aero tech"

Yoda4561
05-15-2010, 04:27 AM
Paint and body is more about cosmetic and restoration aspects than it is performance, at least until until aero becomes a popular topic round here it fits best in advanced technical and performance.

DocJr
05-15-2010, 08:29 AM
I don't think the name of the section should change, but I do feel aero stuff should go in the paint and body section. Afterall, all aerodynamic changes are done to the body. Remember...a slick paint job is more aerodynamic than matte. haha

Gitter Dun
05-15-2010, 07:26 PM
We have gotten to the point where our cars can be competitive with late models mechanically. It only seems logical to me that aerodynamics would be the next level for our cars to go.

How exciting would it be to see the next line of aerodynamic products available for early model pro-touring cars.

As far as forum location, paint, body, and aero sounds fine to me.

DocJr
05-15-2010, 09:30 PM
I would agree. But the thing with aerodynamics...in order for it to be accurate, it needs to be tested, and that's pricey.

Remember Troy's Blowfish? they used Chrysler's wind tunnel. How cool is that!? lol

I think there was an article in Hot Rod some time ago where someone has a facility for "off the street" use, but it's so much $ per day or something like that.

I think the article is from '05 it's called "Kingdom of Air" I remember scanning the article for my Aero notebook in college. I could post the article pages if I'm allowed to lol

Gitter Dun
05-16-2010, 09:31 AM
I have been spending alot of time thinking and researcvhing aero and have found some pretty cool stuff on line.

I will be revamping my valance for radiator and brake cooling air and currently researching how to close off grill area without looking tacky. Most likely from the back of the grill so it goes un-noticed.

There is a kit I found on line that will allow me to do this aside from reconstructing valance.

Another thing I would like to do is figure out a way to slope the nose of the car, but not so extreme that it takes away from the original look.

Also have been looking out for front air dams, spoilers, and rear spoilers.

Wonder what a wind tunnel would cost for the day...

novaderrik
05-16-2010, 05:55 PM
I have been spending alot of time thinking and researcvhing aero and have found some pretty cool stuff on line.

I will be revamping my valance for radiator and brake cooling air and currently researching how to close off grill area without looking tacky. Most likely from the back of the grill so it goes un-noticed.

There is a kit I found on line that will allow me to do this aside from reconstructing valance.

Another thing I would like to do is figure out a way to slope the nose of the car, but not so extreme that it takes away from the original look.

Also have been looking out for front air dams, spoilers, and rear spoilers.

Wonder what a wind tunnel would cost for the day...

i made some grille blockoff plates for my 74 Monte Carlo out of some 20 gauge perforated steel i got out of the scrap bin when i ran a flat laser.
i just formed it to the shape of the back of the grille, painted it Krylon semi gloss black, and used the stock grille mounting bolts to hold it in. i started with about 3/4 of the grille closed off, and kept cutting away more of it from the center of the grille until it maintained temps right around the opening point of the thermostat.

it did make a difference in the way the car feels going down the road- it feels more securely anchored to the ground and the steering is noticeably tighter. i also noticed a 2" increase in engine vacuum at highway speeds, which tells me that it needs less throttle opening to maintain speed.
i've also done a couple of other tricks to that car that helped out. i made a "closeout panel" that takes up the gap between the front bumper and radiator support and added a 4" tall chin spoiler that i got from a mid 80's Caprice in the junkyard.
both of those changes also helped with the way the car feels and how much vacuum it makes going down the road.
my next project is going to be closing off the space between the bumper and inner fenderwells like GM did on the G bodies when they went to the smaller body style in '78, and i also plan to seal off the holes in the radiator support behind the headlights and put a seal between the radiator support and hood to help direct airflow thru the radiator instead of around it, which should allow me to close off more of the grille..
someday, the bumpers are going to get sectioned in about 1" on each side to pull them in out of the air and flow better with the body lines, and the bumper shocks are going to get removed to suck them into the body 4". i don't know if that last thing counts as an aero thing, but it will make the car look better. i'm also gonna ditch the roof rain channel thingies and contour the B pillar to make a smoother transition from the door glass like they did on the NASCAR racers.

Gitter Dun
05-16-2010, 07:16 PM
i made some grille blockoff plates for my 74 Monte Carlo out of some 20 gauge perforated steel i got out of the scrap bin when i ran a flat laser.
i just formed it to the shape of the back of the grille, painted it Krylon semi gloss black, and used the stock grille mounting bolts to hold it in. i started with about 3/4 of the grille closed off, and kept cutting away more of it from the center of the grille until it maintained temps right around the opening point of the thermostat.

it did make a difference i nthe way the car feels going down the road- it feels more securely anchored ot he ground and the steering is noticeably tighter. i also noticed a 2" increase in engine vacuum at highway speeds, which tells me that it needs less throttle opening to maintain speed.
i've also done a couple of other tricks to that car that helped out. i makde a "closeout panel" that takes up the gap between the front bumper and radiator support and added a 4" tall chin spoiler that i got from a mid 80's Caprice in the junkyard.
both of those changes also helped with the way the car feels and how much vacuum it makes going down the road.
my next project is going to be closing off the space between the bumper and inner fenderwells like GM did on the G bodies when they went to the smaller body style in '78, and i also plan to seal off the holes in the radiator support behind the headlights and put a seal between the radiator support and hood to help direct airflow thru the radiator instead of around it, which should allow me to close off more of the grille..
someday, the bumpers are going to get sectioned in about 1" on each side to pull them in out of the air and flow better with the body lines, and the bumper shocks are going to get removed to suck them into the body 4". i don't know if that last thing counts as an aero thing, but it will make the car look better. i'm also gonna ditch the roof rain channel thingies and contour the B pillar to make a smoother transition from the door glass like they did on the NASCAR racers.

That is totally cool, and the next thing I will be working on. God knows our cars are in serious need of aero help.

sik68
05-16-2010, 09:16 PM
That is totally cool, and the next thing I will be working on. God knows our cars are in serious need of aero help.

Yeah 69's are real bricks!


I don't have a shifter boot yet...driving down the road yesterday I couldn't believe how much air was gushing into my car through the shifter hole cutout. And that was at 65mph... I can't imagine how much lift is generated in these cars at any sort of real speed. I know Big Red camaro has an altered looking nose. It's really raked down.

Gitter Dun
05-16-2010, 11:24 PM
Yeah 69's are real bricks!


I don't have a shifter boot yet...driving down the road yesterday I couldn't believe how much air was gushing into my car through the shifter hole cutout. And that was at 65mph... I can't imagine how much lift is generated in these cars at any sort of real speed. I know Big Red camaro has an altered looking nose. It's really raked down.

Yeah, I was wondering about Big Red's aero. Didn't that beast average 200 mph at an event running through Nevada?

Bryce
05-17-2010, 07:15 AM
.....
someday, the bumpers are going to get sectioned in about 1" on each side to pull them in out of the air and flow better with the body lines, and the bumper shocks are going to get removed to suck them into the body 4". i don't know if that last thing counts as an aero thing, but it will make the car look better.

The front bumper sticking forward of the grill can be more aerodynamic that sucking it in. The farther forward the front valance is the more you can divert the air from hitting the grill.

novaderrik
05-17-2010, 07:41 AM
The front bumper sticking forward of the grill can be more aerodynamic that sucking it in. The farther forward the front valance is the more you can divert the air from hitting the grill.
yeah, but it looks like crap. i'm not building an all out race car here.

Bryce
05-17-2010, 08:04 AM
yeah, but it looks like crap. i'm not building an all out race car here.


WORD. I totally agree with you! Just thought I would clarify for anyone looking for ultimate aero tricks.

DocJr
05-17-2010, 08:11 AM
haha you guys made me chuckle.

In school I had made a comment that made me "less of a designer"

I had made the comment, "Yea? well areodynamic cars are ugly!"

I mean really? look at a prius...

but yea, anyways, aero tricks are cool, but I wouldn't sacrifice the whole look of your car.

John Wright
05-17-2010, 09:02 AM
Yeah, I was wondering about Big Red's aero. Didn't that beast average 200 mph

Lots of reading here:

http://www.bigredcamaro.com/newsite/mainpage.html

Gitter Dun
05-17-2010, 11:00 AM
Lots of reading here:

http://www.bigredcamaro.com/newsite/mainpage.html

Thanks John.

Wow, a dedicated web site, that car is amazing. I dont know how RJ drives that fast sitting on his monstrous size balls, LOL.

I've seen 140 mph in my car but 220 mph. Holy guacamoli!!

John Wright
05-17-2010, 11:20 AM
Oh yeah..big red is bad to da bone.

ammoyer
05-18-2010, 11:04 AM
Driving home down I-25 yesterday I saw some vortex generators on the rear sides of a Jeep Cherokee. I believe they were the AirTab ones. There were 3-4 on the sides of the Jeep at the rear edge of the side and 3 more at the rear edge of the side glass. Wonder if it helps with his mileage.

Keep your eyes open... aero is everywhere.

Yoda4561
05-18-2010, 02:15 PM
AHAH!! I been looking for this article for days. Here's some quantitative wind tunnel tested #'s for aero tricks on our cars. The lower the Cd the better. Their early 2nd gen camaro got .49 with no spoiler, and managed .29 after all their mods (including a spoiler, apparently they don't ALWAYS increase drag). Here's some interesting numbers off wiki, C6's are around .28-.30, the Prius around .26, a 69 Charger Daytona and surprisingly the 84 transam with the right factory options is around .29 .

http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/photo_03.html

And the rest of the article.

http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/index.html

Bjkadron
05-19-2010, 07:49 PM
Good Discussion guys! I am getting ready to start an aero program for my duster.. Since I have one running and one in progress.. I'll post the results as I get them.

Gitter Dun
05-19-2010, 08:00 PM
AHAH!! I been looking for this article for days. Here's some quantitative wind tunnel tested #'s for aero tricks on our cars. The lower the Cd the better. Their early 2nd gen camaro got .49 with no spoiler, and managed .29 after all their mods (including a spoiler, apparently they don't ALWAYS increase drag). Here's some interesting numbers off wiki, C6's are around .28-.30, the Prius around .26, a 69 Charger Daytona and surprisingly the 84 transam with the right factory options is around .29 .

http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/photo_03.html

And the rest of the article.

http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/index.html

Great article, cant wait to start my aero work!!

The Stickman
05-20-2010, 08:45 PM
Wow that article taught me something. I need to find a way to close up the gap between my hood and windshield.

Bjkadron
05-21-2010, 08:48 AM
Wow that article taught me something. I need to find a way to close up the gap between my hood and windshield.

On which car?

The Stickman
05-23-2010, 03:38 AM
On which car?

On me Olds Custom Cruiser. I think i am going to make a removable panel with Dzus fasteners that way if I am out and it looks like rain I can pull it off.

The Stickman
03-15-2011, 06:52 AM
I found 2 more articles from this series.
http://www.autospeed.com.au/cms/A_2455/article.html
http://www.autospeed.com.au/cms/A_2456/article.html

The Stickman
03-15-2011, 07:02 AM
And another.
http://www.autospeed.com/A_109937/cms/article.html