Page 1 of 4 123 ... LastLast
Results 1 to 10 of 32

Thread: Racecar Eng. aero article compilation

  1. #1
    Advanced Tech? verified Feedback Score 0 i3igpete's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Posts
    948
    Thanks
    159
    Thanked 139 Times in 87 Posts

    Racecar Eng. aero article compilation

    http://www.rightwheeldrive.com/Aero_articles.zip

    pretty cool series of articles, don't know if it's been posted on here before. Some interesting things I've found so far:

    -double airfoil wings can be run with really steep secondary airfoil angles and still build downforce (v14n9)
    -installing smooth underbody panels have a negligible effect on drag (v15n1)
    -nascar-type spoilers are actually pretty effective (maybe someone should try this!) (v15n2, n3)
    -splitter-to-ground clearance doesn't matter much at all for downforce, classical theory doesn't work due to high viscous effects (v14n5)
    Maddog Performance Engineering

  2. The Following 3 Users Say Thank You to i3igpete For This Useful Post:


  3. #2
    Relax, it's just rocket science! Feedback Score 13 (100%) BigTyla's Avatar
    Join Date
    Sep 2010
    Owner Since
    Nov 2001

    Location
    Ozark, AL
    Posts
    1,220
    Blog Entries
    2
    Thanks
    55
    Thanked 122 Times in 76 Posts
    Damn it, why did you have to post this? You KNOW posting "aero" in any article is like a magnet drawing me in and forcing me to read the material!

    Will have to read at lunch and try to provide some commentary.

  4. #3
    Banned Feedback Score 11 (100%) J. Fast's Avatar
    Join Date
    Sep 2010
    Owner Since
    - O - SIX -

    Location
    Colorado, USA
    Posts
    2,755
    Thanks
    412
    Thanked 203 Times in 143 Posts
    This is my wing.
    Bought it from some ebay guy who makes these in his spare time in China. It was $365 with the CF uprights. I picked it for the chord and never knew there was CFD info on it so... sweet! So much more downforce when you combine two different wings? I didn't really get the tradeoff portion of the two wing, I sort of rushed thru the articles since I didn't have much time. Was it increased drag with speed?

  5. #4
    Banned Feedback Score 11 (100%) J. Fast's Avatar
    Join Date
    Sep 2010
    Owner Since
    - O - SIX -

    Location
    Colorado, USA
    Posts
    2,755
    Thanks
    412
    Thanked 203 Times in 143 Posts
    Another picture that was emailed from the builder It is 64" wide

  6. #5
    Advanced Tech? verified Feedback Score 0 i3igpete's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Posts
    948
    Thanks
    159
    Thanked 139 Times in 87 Posts
    there's really no trade off at all, a dual-element wing can run a ridiculous amount of camber that a single element will stall with. Consequently, he can probably jack up the angle on that second element without stalling it.

    btw, is that a voltex knock-off?
    Last edited by i3igpete; 06-30-2011 at 02:27 PM.

  7. #6
    Relax, it's just rocket science! Feedback Score 13 (100%) BigTyla's Avatar
    Join Date
    Sep 2010
    Owner Since
    Nov 2001

    Location
    Ozark, AL
    Posts
    1,220
    Blog Entries
    2
    Thanks
    55
    Thanked 122 Times in 76 Posts
    I have read the first four articles, but V14N5 (talking about underbody venturi tubes) really drew my attention. Some comments:

    1) I can imagine that spillover effects would be significant in this problem. I'd really be interested in seeing some 3-D numbers but I understand the reason for staying 2-D here since 3-D is not only more complex but is also significantly more computationally expensive. I'm happy to see the author mention that steeper diffuser angles would be permitted by 3-D effects. He knows his stuff for sure!

    2) Air speed at the inlet was never specified in the problem. This is a critical variable as it would seem ideal to design the venturi tube with the most frequent air speed in mind (or the situational speed at which maximum possible downforce is desired). A venturi designed specifically for the vehicle's top speed might end up operating terribly during cornering speeds. That leads me to question whether the flow within the venturi tube would ever be anything other than fully-developed turbulence, as a boundary layer in the process of transition will show significantly higher flow separation penalties at the diffuser than the fully-developed case. Of course this can be solved trivially by integrating vortex generators in the venturi design, deliberately tripping the flow to fully-developed turbulence.

    3) Why not design the diffuser wall with camber to reduce flow separation penalties? Seems like a pretty obvious solution to me. It's not like cambering the diffuser is hard or expensive, particularly with sheet metal designs.

  8. #7
    Member verified Feedback Score 0 DocWalt's Avatar
    Join Date
    Sep 2010
    Owner Since
    Oct '08 - Oct '10

    Location
    Royersford, PA
    Posts
    3,689
    Blog Entries
    1
    Thanks
    1,017
    Thanked 430 Times in 306 Posts
    Racecar Engineering is fascinating, I've been subscribing for a while now and it's always a fun day when I get a new issue, lol.
    R135
    ╚╬╬╝
    - 24

  9. #8
    Relax, it's just rocket science! Feedback Score 13 (100%) BigTyla's Avatar
    Join Date
    Sep 2010
    Owner Since
    Nov 2001

    Location
    Ozark, AL
    Posts
    1,220
    Blog Entries
    2
    Thanks
    55
    Thanked 122 Times in 76 Posts
    Quote Originally Posted by DocWalt View Post
    Racecar Engineering is fascinating, I've been subscribing for a while now and it's always a fun day when I get a new issue, lol.
    How much is the subscription now? I was looking at those issues and $9 per month is pretty steep!

  10. #9
    Advanced Tech? verified Feedback Score 0 i3igpete's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Posts
    948
    Thanks
    159
    Thanked 139 Times in 87 Posts
    Quote Originally Posted by BigTyla View Post
    I have read the first four articles, but V14N5 (talking about underbody venturi tubes) really drew my attention. Some comments:
    He does a bunch of 3D analyses later, but I was mainly intrigued how different reality was from Bernoulli. Very interesting how the downforce is almost constant, regardless of the clearance.

  11. #10
    Relax, it's just rocket science! Feedback Score 13 (100%) BigTyla's Avatar
    Join Date
    Sep 2010
    Owner Since
    Nov 2001

    Location
    Ozark, AL
    Posts
    1,220
    Blog Entries
    2
    Thanks
    55
    Thanked 122 Times in 76 Posts
    Quote Originally Posted by i3igpete View Post
    He does a bunch of 3D analyses later, but I was mainly intrigued how different reality was from Bernoulli. Very interesting how the downforce is almost constant, regardless of the clearance.
    It is very intriguing, but it makes total sense. I think it brings to light the fact that "venturi" is kind of a misnomer here because it isn't a closed system. You'd see results much more in line with Bernoulli's principle if you closed off the bottom. You'd also add weight and have people wondering why you were carrying a ramjet under your car.

Page 1 of 4 123 ... LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
The 3000GT/Stealth/GTO Web History Project
3000gt.com
3000GT / Stealth International WWWboard Archive
Jim's (RED3KGT) Reststop
3000GT/Stealth/GTO Information and Resources
Team 3S
3000GT / Stealth / GTO Information
daveblack.net
3000GT/Stealth/GTO Clubs and Groups
Michigan 3S
MInnesota 3S
Wisconsin 3S
Iowa, Nebraska, Kansas 3S
North California 3000GT/Stealth
United Society of 3S Owners
3000GT/Stealth/GTO Forums
3000GT/Stealth International
3000GT/Stealth/GTO Event Pages
3S National Gathering
East Coast Gathering
Upper Mid-West Gathering
Blue Ridge Gathering