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The Little Fins Under The Car

Discussion in 'Gen 3 Prius Main Forum' started by El Dobro, May 18, 2013.

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  1. szgabor

    szgabor Active Member

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    They are right next to the wheels and the coils of the suspension which is creating a "tiny little bit" of turbulence ... so these things would "smooth" the airflow at most in the middle third at best.

    Again surely they do something I am just skeptical about the real effect your 1-2% is a number 1-2% of what ? ... Do you mean mpg or just air resistance?
     
    #41 szgabor, Jun 27, 2013
  2. David Beale

    David Beale Senior Member

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    Air resistance. Would have almost no effect on fuel use. There are too many variables to even measure that!
     
    #42 David Beale, Jun 27, 2013
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  3. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The airflow at the rear of any vehicle is important. many piston engine airplanes have a non aerodynamic front but all have aerodynamic tails.

    [​IMG]

    Race cars are different as they are wanting downforce, not MPG.
     
    #43 JimboPalmer, Jun 27, 2013
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  4. El Dobro

    El Dobro A Member

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    What I was saying is that I don't remember seeing any diffusers on the back bumper, not why would there be any on it.
     
    #44 El Dobro, Jun 27, 2013
  5. WE0H

    WE0H Senior Member

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    The Swagger has fins too :)

    Mike

    Mobile on my SGH-i717
     
    #45 WE0H, Jun 27, 2013
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Yeah. I recall someone from Japan mentioning that the base models there (S Grade) don't have the underbody covers (front cover and rear skirt.. that tiny sliver of black plastic protruding from the rear bumper) and it's standard on G grades. The extra weight of the plastics apparently offset the gains in smooth air flow. Not sure how the dealer can quantify that. It's possible that Toyota is trying all sorts of methods to minimise back pressure - the longer rear spoiler, the aerocorners for the rear bumper and the underbody fins and rear skirt.

    They've even added little bumps near the mirrors in newer models. I'm sure you've heard it in advertisement for the Camry. They're called "Vortex Generators" and create "controlled" turbulent airflow along the side of the car to increase high speed stability.
     
    #46 Tideland Prius, Jun 27, 2013
  7. El Dobro

    El Dobro A Member

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    Any pics? Lexus said they're putting air-benders on their mirrors, but I can't find a pic.
     
    #47 El Dobro, Jun 27, 2013
  8. WE0H

    WE0H Senior Member

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    The 2013 RAV4 has them on the mirrors. I can say that rain goes perfectly horizontal across the front door windows with no mirror buffeting.

    Mike

    Mobile on my SGH-i717
     
    #48 WE0H, Jun 28, 2013
  9. Tideland Prius

    Tideland Prius Moderator of the North
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    [​IMG]

    The fin is located near the top of the black triangle at the base of the mirror.
     
    #49 Tideland Prius, Jun 29, 2013
  10. El Dobro

    El Dobro A Member

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    A tiny little thing, but I guess it's doing its job.
     
    #50 El Dobro, Jun 29, 2013
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    #51 Tideland Prius, Jun 30, 2013
  12. szgabor

    szgabor Active Member

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    #52 szgabor, Jun 30, 2013
  13. David Beale

    David Beale Senior Member

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    I would have to agree. I'm sure they do -something-, but I'm also confident you (or they) couldn't measure what it is. Think golf balls. Lots, and I repeat, lots of tiny dimples help them fly farther. So one manufacturer made the dimples larger by making them hexagons so they would "nest" closer together. The ball performed "better". That is, it went about 5% farther under the same conditions. Is that "better"? Many golfers think so. They are willing to pay around three times as much for them. I just found the ball went deeper into the woods when I hit it. ;)
     
    #53 David Beale, Jun 30, 2013
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  14. WE0H

    WE0H Senior Member

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    Wonder if a hailed out vehicle gets better mpg's because of lower wind drag? ;)

    Mike
     
    #54 WE0H, Jun 30, 2013
  15. El Dobro

    El Dobro A Member

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    #55 El Dobro, Jun 30, 2013
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  16. szgabor

    szgabor Active Member

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    Yes "couldn't measure what it is." yes this is ONE of my reason to be being skeptical TWO clearly this is nothing to do with the Bernoulli principle ... so WHY bringing this up time and time again ... sure it makes a cool YouTube video but "aribenders" are NOTHING to do with that... I do understand laminar flow and why that is a good thing fighting air resistance ... but please someone should share some test data ... different speeds over drag .. if it is under controlled circumstances .. even better. Laminar flow at the operating speed of prius is a very little factor (I am not an air/flow science engineer though) anyone with those skill please comment
     
    #56 szgabor, Jun 30, 2013
  17. El Dobro

    El Dobro A Member

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    Video was in reply to WEOH's post, not this thread.
     
    #57 El Dobro, Jun 30, 2013
  18. WE0H

    WE0H Senior Member

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    Saweet :) Wonder what a glossy finish car would look like with the dimples? 3+ mpg is a decent gain.

    Mike
     
    #58 WE0H, Jun 30, 2013
  19. El Dobro

    El Dobro A Member

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    Here you go, about 45 seconds into the video.

     
    #59 El Dobro, Jul 20, 2013
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  20. szgabor

    szgabor Active Member

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    #60 szgabor, Jul 21, 2013
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