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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 01-14-2012, 03:58 PM   #1 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 10,460
Thanks: 16,067
Thanked 5,556 Times in 3,320 Posts
SCTA El Mirage racing images GOOGLE/bing

As part of my trailer research I've spent some time looking at GOOGLE and Bing images for the Southern California Timing Association's dry lakes racing at El Mirage.
Smoke rake wind tunnel images just don't do justice to an automobiles actual wake turbulence.
Images are presented for fastback,notch back,square back,motorcycles,lakesters,and streamliners.
Anyone who has not seen such photos,owes it to themselves to take a look.
These are the 'money-shots.' For the power available at your drive-wheels,on the highway,this is where the majority of your driving cost is absorbed.
After looking,you may never quite think about the back of your car the same way.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 01-14-2012, 04:24 PM   #2 (permalink)
Master EcoModder
 
Sven7's Avatar
 
Join Date: Aug 2011
Location: Warren, MI
Posts: 2,456

Boo Radley - '65 Ford F100
90 day: 13.28 mpg (US)
Thanks: 782
Thanked 664 Times in 407 Posts
It's not clear which images you searched for but here are a few.

It's apparent a lot of the cars have functional spoilers. The dust in the wake is not making its way to the rear window, which suggests the airflow is strong there, and not eddying so much as i'd expect. Does this mean the spoiler is pushing the flow back into its "ideal" profile?

Capri


Some sort of streamliner


Barracuda


XKE(?) bodied streamliner


Model A


Chevy Monza


Americamaro


'52 ish Ford?
__________________
He gave me a dollar. A blood-soaked dollar.
I cannot get the spot out but it's okay; It still works in the store
  Reply With Quote
The Following 2 Users Say Thank You to Sven7 For This Useful Post:
aerohead (01-14-2012), JasonG (01-14-2012)
Old 01-14-2012, 04:42 PM   #3 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 10,460
Thanks: 16,067
Thanked 5,556 Times in 3,320 Posts
pics

Thanks Sven7,I realize it's a lot of pages to peruse but there lay the lesson.Thanks again!
  Reply With Quote
Old 01-14-2012, 04:53 PM   #4 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 10,460
Thanks: 16,067
Thanked 5,556 Times in 3,320 Posts
spoilers

The spoilers are moving the separation point back,capturing a locked-vortex in front of,and above,and providing a inpenetrateble(sp?) barrier in which to sequester the lower pressure of the wake behind and below,producing safe amounts of downforce while cutting drag.
If we could inject smoke at the backlight I think we'd see the vortex.(cars with roof only of course).
  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
Sven7 (01-14-2012)
Old 01-14-2012, 05:04 PM   #5 (permalink)
Master EcoModder
 
Sven7's Avatar
 
Join Date: Aug 2011
Location: Warren, MI
Posts: 2,456

Boo Radley - '65 Ford F100
90 day: 13.28 mpg (US)
Thanks: 782
Thanked 664 Times in 407 Posts
Quote:
Originally Posted by aerohead View Post
The spoilers are moving the separation point back,capturing a locked-vortex in front of,and above,and providing a inpenetrable [] barrier in which to sequester the lower pressure of the wake behind and below,producing safe amounts of downforce while cutting drag.
If we could inject smoke at the backlight I think we'd see the vortex.(cars with roof only of course).
So essentially it's using a vortex on the rear window and trunk area to guide the upper air over it cleanly, while creating downforce. Kind of like a virtual Kammback, if you will. How does this effect help the attachment of airflow?

Is there a practical difference between those Nascar type spoilers (Barracuda) and the flat ones (Monza)?



__________________
He gave me a dollar. A blood-soaked dollar.
I cannot get the spot out but it's okay; It still works in the store
  Reply With Quote
Old 01-14-2012, 05:38 PM   #6 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 10,460
Thanks: 16,067
Thanked 5,556 Times in 3,320 Posts
types

Quote:
Originally Posted by Sven7 View Post
So essentially it's using a vortex on the rear window and trunk area to guide the upper air over it cleanly, while creating downforce. Kind of like a virtual Kammback, if you will. How does this effect help the attachment of airflow?

Is there a practical difference between those Nascar type spoilers (Barracuda) and the flat ones (Monza)?



Both can give the outer flow a place to re-attach to,and then flow beyond there will skip over (you must pay for energy to feed the circulating vortex though!) which is what cuts drag.
The NASCAR spoiler angle will vary from track to track depending on length,bank,and speeds.And they'll change after qualifying runs,once they get into 'traffic' of racing,where the surrounding cars are getting or losing their air.The angles will be a compromise between speed and downforce.
At Bonneville,the spoiler will also be a compromise between drag and downforce with the added variable of parachute deployment.Typically,the drag chutes are angled to fire on an upward trajectory to catch the air above the spoiler line.Wheel traction is a big issue at Bonneville.Some of the cars are so powerful that they can spin the wheels at many hundreds of miles per hour.And at those speeds,if the car gets sideways they become crude airfoils and lift off.Very scary!
Streamliners fire straight back,but they're so clean the chutes have no problem.Terry Nish includes VGs at the back of his Royal Purple streamliner to guarantee quality onset flow to the dual chutes.If they fail,it's very hard on the brakes even if ceramic.He told me( if my memory serves me) that he coasted for 10-miles once when the chutes failed to deploy.

  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
Sven7 (01-15-2012)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com