Tip Vortex From a Shallow Foil

Discussion in 'Hydrodynamics and Aerodynamics' started by Doug Halsey, Dec 24, 2018.

  1. Doug Halsey
    Joined: Feb 2007
    Posts: 640
    Likes: 212, Points: 53, Legacy Rep: 160
    Location: California, USA

    Doug Halsey Senior Member

    Here's a shot of what I think is a tip vortex surfacing a short distance aft of a foil.

    Any observations?

    The boat is American Magic & the photo is part of a short sequence in the following video:
     

    Attached Files:

    Doug Halsey, Dec 24, 2018
    #1
    BlueBell and Doug Lord like this.
  2. BlueBell
    Joined: May 2017
    Posts: 2,704
    Likes: 979, Points: 113
    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    Good for you Doug H.
    I watched that video last night and completely missed it.
    So cool... well, sort-of.
     
    Last edited: Dec 24, 2018
    BlueBell, Dec 24, 2018
    #2
  3. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    That tip must be very close to the surface-much closer than I would have thought they'd want......
     
    Doug Lord, Dec 24, 2018
    #3
  4. Doug Halsey
    Joined: Feb 2007
    Posts: 640
    Likes: 212, Points: 53, Legacy Rep: 160
    Location: California, USA

    Doug Halsey Senior Member

    Looking at the video more carefully, I see the foil encountering small waves and rising & falling. The screenshot I've shown is close to the top of that motion & probably isn't something they would maintain for very long.

    In a steady condition, the tip vortex would tend to sink, not rise. But I can easily imagine the oscillations allowing it to break the surface like that.
     
    Doug Halsey, Dec 24, 2018
    #4
  5. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    My compliments! You caught something that was easy to see when I knew it was there but I simply didn't see it until you pointed it out. Maybe it is a characteristic of the thing being flown manually-which it has to be to be legal-at least on the 75? Thanks for the heads up.
    Have a great Christmas and spectacular New Year!
     
    Doug Lord, Dec 24, 2018
    #5

  7. BlueBell
    Joined: May 2017
    Posts: 2,704
    Likes: 979, Points: 113
    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    Agreed Doug H.
    I saw the same thing on review, frame by frame, stop-motion.
    I'm just so glad you brought it to our attention.

    Cheers
     
    BlueBell, Dec 24, 2018
    #6
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