L- vs inverted T-hydrofoils on sailboats

Discussion in 'Hydrodynamics and Aerodynamics' started by bjn, Mar 19, 2018.

  1. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Ideas for possible use on the Fire Arrow Test Model or on any boat with similar foils: (See Tom Speer's post # 15 on previous page)

    FOIL-Spring Controlled Flapped Foil.jpg


    Foil-L plus flap plus wand.jpg
     
    Last edited: Mar 27, 2018
  2. OzFred
    Joined: Nov 2015
    Posts: 507
    Likes: 54, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    Yep, all very old quotes from a decade ago or more when foiling Moths were pretty new and it might have been hip to use the term. Frank Bethwaite used it once, in inverted commas, on page 400. On page 53 there is a picture with a caption:

    "Rohan Veel sailing a foil [sic] Moth - note the typical windward heel."​

    So his use of the term was no endorsement. No one but you uses it now. I spent nearly 10 years sailing a Moth, went to state, national and a world championships and didn't hear the term once. There was talk of windward heal though.

    And if "Veel Heal" includes "bow up", then it hasn't been used for nearly a decade. Early on, Bladeriders had a distinct bow up attitude due to the stock foil not having enough AoA when sailed flat in pitch so made overuse of the flap for lift. A simple fix was to shim the heel of the strut inside the foil to increase the angle of incidence, so the boat could be sailed flat in pitch with a more neutral flap.
     
  3. OzFred
    Joined: Nov 2015
    Posts: 507
    Likes: 54, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    Thanks Tom, plenty of food for thought. It would be nice to have some simple diagrams or screen captures, not all of us have access to the programs you mention for analysis. In particular I have trouble imagining your example of looking up at a T foil and seeing it as a Y. I can do that for a Moth healed to windward, but not for a catamaran sailing flat. :)
     
  4. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ===============================
    The fact is that Veal Heel is not the same as windward heel on any non-foiler. Whether you or anyone else choose to use the correct term or not is your problem,not mine.
    Oh, and 10 years ago foiling Moths had already been around 9 years!! Many people don't know history--that fact doesn't change history-or at least it shouldn't.
     
    Last edited: Mar 25, 2018
  5. philSweet
    Joined: May 2008
    Posts: 2,346
    Likes: 206, Points: 63, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    Oz,

    Look at the boat bow on back along the course being sailed. You have hydro side force and hydro vertical force in this frame. Combine the vectors, then set this as the new z axis, z'. y' is to the right, x' is along the course out of the page. The horizon is tilted in this plane. This lets you analyze the problem of lifting surfaces with general shapes in the y'z' plane. Or at least talk about them with reference to some target solutions. Span is now the projection of the submerged foil on y'. Lift is the total hydro force. Induced drag is in the direction of travel.
     
  6. OzFred
    Joined: Nov 2015
    Posts: 507
    Likes: 54, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    Not sure what your "10 years ago" reference is about. By 2008 there were Bladeriders, Prowler Zeros and some home builds and conversions in my local fleet. It was the year I bought my first Moth. 9 years before 2008 (1999) doesn't match with anything of particular note, though it's the year after Ian Ward used a wand/flap arrangement a bifoiler Moth.

    According to the UK International Moth site, the first foiling Moth was in 1974 so by 1999 foiling Moths had been around 25 years. So I'm not sure what point you're trying to make.

    Back to windward heal. Rohan was instrumental in early development of foiling Moth sailing techniques and probably also the first to be able to routinely foil tack, but he didn't invent the technique of sailing a foiling Moth healed to windward, that honour likely goes to one or more of the group of people who first developed Ian Ward's bifoiler design to the stage of it becoming a viable commercial product.
     
  7. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    ==========================
    Absolutely false.
    John Ilett was the first to produce a foiling Moth with a wand controlled mainfoil. I know for a lot of reasons -one was in 1999 I was finishing the tooling for the F3 rc foiler-the first production rc foiler in history. I called John Illet late that year and he told me of his plans for the forward mounted wand on the Moth.
    Brett Burvill foiled his surface piercing foil equipped Moth in 1999 and David Lugg flew his I14 that same year with manual altitude control..

    http://www.foilingweek.com/blog/201...d-champion-from-victoria-returns-to-the-fold/

    This picture was taken in late 2000 and was published in the mag in Fall of 2001 about the time John started producing the first moths with wands:

    F3 foiler.jpg
     
    Last edited: Mar 27, 2018
  8. OzFred
    Joined: Nov 2015
    Posts: 507
    Likes: 54, Points: 28, Legacy Rep: 16
    Location: Earth

    OzFred Senior Member

    If you're going to say something is false, you should produce some evidence for your statement. The UK Moth site claims that the group that developed the first successful bifoiler moth "…sold their first production version to Rohan Veal". There's no way they could have developed the boat that far without learning to sail it, which would have required windward heal.

    Here is a picture of John Ilett sailing an early model in 2002, healed to windward, from the UK Moth site.

    [​IMG]

    Rohan was a much better sailor than the Perth guys who originally developed the foiling Moth, and was certainly the best of all the early adopters as shown by the results from the 2005 Worlds.
     

  9. Doug Lord
    Joined: May 2009
    Posts: 16,654
    Likes: 326, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    I did from foiling week. This also is relevant: Higher Performance Sailing https://books.google.com/books?id=iQQoAAAAQBAJ&pg=PA400&lpg=PA400&dq=Veal+Heel+for+foilers&source=bl&ots=5TPOZtu3iA&sig=bOzG7UqJs3wZJ9KpgINx2UYXc5Y&hl=en&sa=X&ved=0ahUKEwin9rze-4DaAhXJzFMKHWXlDXoQ6AEIXjAK#v=onepage&q=Veal%20Heel%20for%20foilers&f=false
    ------
    The "group" that developed the wand equipped Moth foiler was primarily John Ilett and his brother Garth. Rohan figured out how to race the boat effectively by developing Veal Heel............
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.