More aerodynamics?

Discussion in 'General' started by fastfreddie, Sep 1, 2020.

  1. fastfreddie

    fastfreddie Midnight Oil Garage

    Golfballs are dimpled for aerodynamic reasons, smoothing out airflow to create less turbulence.
    We've seen drilled upper fairings whose purpose was to balance air pressure behind the "bubble" to decrease turbulence, so...
    Cost argument aside, why not dimpled fairings?
     
  2. Sabre699

    Sabre699 Wait...hold my beer.

  3. backbone

    backbone scarred for life

    I thought somebody had them once, I forget what team it was though.
     
  4. Phl218

    Phl218 Lemme ask my wife

    wild guess:

    shape



    the complicated shape of a motorcycle renders the effectiveness of the dimples pointless

    a golf ball has the simplest shape of all in relation to its motion, thereby giving the effect more validity
     
    sbk1198 likes this.
  5. HPPT

    HPPT !!!

    Golf balls are round. That might be a significant difference. I would imagine that if it worked for flat surfaces, someone in F1 would've done it until they banned it.
     
  6. Robby-Bobby

    Robby-Bobby Steeltoe’s Daddy

    Arent the dimples for helping the spin also? Kinda like rifle too. Are we gonna make little grooves?
     
  7. nigel smith

    nigel smith Well-Known Member

    The original CBR900 had holes in the fairing. They were like bold new graphics, but cheaper to produce. A temporary increase in large drill bit sales ensued.
     
    TurboBlew and Raceless man like this.
  8. rafa

    rafa Well-Known Member

    Its rare that motorcycle are spinning like golf balls do.
     
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  9. fastfreddie

    fastfreddie Midnight Oil Garage

    Shape. The leading face of a fairing isn't that much different than the leading face of a ball, is it? It's the smooth face presented to the force of air resistance creating turbulence that detracts from laminar flow. The dimples provide a boundary layer that promotes laminar flow. (Spinning may have a lot, or not, to do with it.)

    Leading edges on F1 aero-packages are really narrow but I think there may still be some benefit, same as vortex generators that, reportedly, have little effect. But, effect they have, nonetheless.

    Rifling is to impart spin for stabilizing the projectile.
    And, no, dimples would be of zero effect on supersonic projectiles. Might work on fat and slow FMJ like 230gr .45ACP. ?

    I agree the spin part of the equation needs to be quantified as a factor.
     
  10. HPPT

    HPPT !!!

    Do we know for sure that the dimples provide their greatest benefits on the "leading face" of the ball?
     
  11. stangmx13

    stangmx13 Well-Known Member

    This is backwards. Dimples on a golfball create more turbulence. Turbulent flow has more energy, which reduces flow separation. This reduces pressure drag behind the ball.

    Larger shapes usually can’t take advantage of this because the flow separation isn’t comparable, see Reynolds number. Someone tried dimples on an airplane decades ago and it was a failure.

    F1 has vortex generators to impart more energy into flows. GP could do the same. I’d put them on the sides of the upper to increase turbulence around the hands & clipons. I think some teams already do.
     
  12. ChemGuy

    ChemGuy Harden The F%@# Up!

    Round is a horrible shape for air flow.

    Round has several times omre drag than a streamlined shape at anything above a few mph. I've seen an old BW video...at 210mph a streamlined airfoil had 1 lb of drag. A round tube the diameter the same as the max thickness of the airfoil was 9.3x as much drag.

    The dimples on a golf ball create a thin turbulent boundary layer on the surface to help keep the flow around the ball more laminar (ie lower drag) and also to help the air pressure from the back spin create more height. they say an dimpled ball would go ~half as far as a dimpled one.
     
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  13. gixxerboy55

    gixxerboy55 Well-Known Member

    Just start dimpling and let us know how it works out.
     
  14. notbostrom

    notbostrom DaveK broke the interwebs

    You guys just like being able to use the word laminar
     
    TurboBlew and ChemGuy like this.
  15. ChemGuy

    ChemGuy Harden The F%@# Up!

    No.
    See above.
    Its all about the boundary layer for the back half. The air would separate and get very turbulent (ie draggy) at about the mid point. the dimples keep this air attached and flowing more smoothly for much longer.

    Papa may have heard the phrase laminar flow wing. Its a wing designed to keep smooth laminar flow over the whole, or most of the wing. Its associated with high speed and high efficiency.

    So to summarize...laminar flow= good...smooth attached flowing air (or water or whatever liquid/gas you want). Turbulent flow = bad...draggy, detached air flow. unless its a tiny turbulent boundary layer..then it helps keep the rest of the flow laminar.
     
  16. OGs750

    OGs750 Well-Known Member

    :stupid:

    The dimples help keep the flow attached longer which reduces form drag. Dimpling a rider’s suit would make more sense than the fairing.
     
  17. HPPT

    HPPT !!!

    I was trying to be polite. :D
     
    ChemGuy likes this.
  18. fastfreddie

    fastfreddie Midnight Oil Garage

    I should have made the distinction between the boundary layer and the object as a whole, but that's part of the learning process when it comes to seeking answers to technical questions.
    This is the point that was the catalyst for my question.
     
  19. Mongo

    Mongo Administrator

    Wasn't there a song about that? By Enya or the like - Laminar Flow....

    :D
     
  20. fastfreddie

    fastfreddie Midnight Oil Garage

    Goddammit, this thread is about physical technicalities, not some marketed feelz.
    Oh, wait...I forgot the effects of the Beeb factor. :D
     

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