Flight One-a New Kind of Performance One Design Dinghy

Discussion in 'Sailboats' started by Doug Lord, Aug 10, 2011.

  1. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 351, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Flight One / Single curved lifting foil

    Had a bit of a surprise today with a visit by Hugh Welbourn-DSS technology inventor and designer of very fast sailboats. See here for more on the story and pictures: http://www.boatdesign.net/forums/mu...lf-righting-trimaran-test-model-36058-11.html post 154
    I discussed the Single Curved Lifting Foil with him and he was impressed saying that it was very workable-and a really neat idea. From one of the modern pioneers in the application of lifting foils to monohulls that meant a lot to me.

    Here are the rough sketches of the foil, again:
    The foil slides in an athwartship partial trunk and replaces a t-foil for foil assist.
    click on image-
     

    Attached Files:

  2. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 351, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    C Foil

    I was working on a curved foil for the SRT project and decided to see how the single curved foil would actually work on a real boat.
    Boat is 16', 459 lb all-up. The underwater portion of the curved foil was 4' long. The portion of the foil doing the lifting was 1.3sq.'. The aspect ratio of the underwater portion was 7/1. The chord was .57'. The idea was to see what it would take to lift 50% of the all up weight.
    The results were:
    6mph/ 5.2 k speed,lift= 91lb which was 20% of the all up weight,
    8mph/ 7 k speed, lift= 161lb= 35% of all-up weight,
    10mph/ 8.7 k speed,lift= 195lb=42% of all-up weight,
    12mph/ 10.4 k speed,lift= 241.6lb= 53% of all-up weight,
    15mph/ 13k speed, lift= 377.5=81% of all-up weight.
    ----
    The foil would be adjustable allowing the angle of incidence to be varied, the area to be varied and the foil to be 100% retracted. As a "foil assist" board
    it looks like it should work well.
     
    Last edited: Nov 8, 2011
  3. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 351, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    F1-Performance One Design Dinghy

    After thinking about this for a long time I'm thinking that a dinghy application of a curved lifting foil might be considerably improved by using two foils at least in some applications as I mentioned once before.
    Using two foils would allow a narrower hull with greater overall beam and would allow the curved foils(or "L") foils to add righting moment in addition to vertical lift.
    An "L" foil would be mostly retractable and out of the water when the boat is heeled slightly. The "Flight One" concept, using a single curved lifting foil, still is one of the simplest possible incarnations of "foil assist" for a dinghy.
    rough sketches:
     

    Attached Files:

  4. awhapshott
    Joined: Apr 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 26
    Location: Southern England

    awhapshott Junior Member

    An interesting design. Most Cherubs are now on the T-foil, and it is very handy; Not only is the upwind speed good, but the stability increase is well worth having, even if it does make things a little boring (I haven't got the daggerboard out the water on a T-foil boat yet)
    The SK4 foil is brilliant, its planing ability and speed are amazing, although after collision with some Southampton mud at >20kts she is having some serious repair work done.

    With the C-foil, how would the angle of attack be changed? Or would it be fixed?

    Also, in one of your posts there was a thin red hull, with boards/floats projecting under the wing, what on earth is it? It looks like an early moth development.
     
  5. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 351, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    =======================
    I must have missed something-what is the SK4?? Found this: http://www.sailingsource.com/cherub/forum/index.php?topic=51.5;wap2
    The single curved lifting foil would be adjusted just like any curved foil is: the foil would be angled fore and aft and the trunk on each side would be designed to allow that. It could also be done with a slight pivot of the athwartship trunk-though the more I've considered it the less I think a side to side trunk is required.
    ----
    The boat in my last post is based on the Tantra which, I think, is the one you're referring to. It was a prototype using asymetrical, toed-in "leeboards"
    for lateral resistance. Each leeboard had a replaceable tip. Wish I had thought using twin curved foils back then!



    Pictures: Tantra, with 80 sq. US1 rig, circular cockpit with forward traveler, experimental square top rig designed 1975, built 1977. The Tantra II in my last post would be very similar---
     

    Attached Files:

  6. awhapshott
    Joined: Apr 2012
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 26
    Location: Southern England

    awhapshott Junior Member

    (http://www.youtube.com/watch?v=gZHK917eULk) -Shows the effect of the foil, I feel that its definitely a way forwards in skiff development.

    Yep, the Tantra based boat is the one. Looked quite cool.

    Not sure if you've come across it, but a year or so ago I saw a experimental dinghy (Similar to a laser) which has a V shaped keel configuration, with a small bulb held at the bottom. I've been searching and searching for the video of it, but can't find it. It was similar to your idea, but fixed in all aspects, not at all 'beachable' !!
     
    1 person likes this.
  7. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 351, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Yeah I found it-just didn't remember it at all! Here is Kevin Elways "treatise" on rudder t-foils:
     

    Attached Files:


  8. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 351, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    =================
    Thanks for reminding me about the SK4 and the Tantra comments! Mal Smith did a rendering and some design work on a surface piercing foil for a Laser:
     

    Attached Files:

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.