Hydrofoil - trimaran

Discussion in 'Multihulls' started by sub_0, Dec 8, 2015.

  1. sub_0
    Joined: May 2015
    Posts: 15
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    Location: Croatia

    sub_0 Junior Member

    Greeting and hello to everyone

    First of all big thanks in advance for everyone who give they opinion and help on this matter . I m trying to design and build hydrofoil trimaran for school project wich would be powered by internal electric motor . I have some basic knowledge of foilers from Ray Vellinga book also i m on the 5 th year of college and representing myself and my team so we have some background in current topic ....We designed some inicial project wich basic caracteristic :

    -lwl=2.35 m
    -b=1.75(from ama to ama)
    -d=0.45 (main hull)-big depth in for different disciplines
    -Foiler configuration : canard
    -forward foils : surface piercing-2x position wide abeam on amas
    -main foils - t foil on rudder
    -NACA: 64-412 on both forward and aft wings

    Our goal is to register for internacional competition in three disciplines so are boat must be able to do displacement (or semidispalcement ) transfer of 200 kg and two so to say more speed races on the 200 m track ( rectangular track with sharp 90 deg turn on each corner )

    -My question are ?

    -foils configuration goog/bad(t foil carries cca 70 % weight)

    -does main t foil needs addicional hight sensor in current configuration with forward surface piercer ( i think not cuz forward foil will change AOI of t foil , and currently we are not planing to put any addicional height sensor)

    -i was unable to find trimarans foilers WITHOUT sails , also i m concerned about turning manuvers of this ship (shown on pic below) , but i also saw very good flat turns manovers in similar configurations.

    -in order to find balance beetwen weight transport and spped races our first choice is semidiplacement main hull??(what do u think of this)

    -ama design -do they need to have same depth as main hull to provide inicial stability when boat is on the rest or they can have smaller depth like on pic below?

    -ama design -how long they can be in compare to main hull and what cross section do u recomend ?

    -roll menagment by two forward dihedrals ?

    *** pic below was made for purpose of marketing
    *** neglect shape of hulls
    ***forward foils are going to bi relocated on outer side of amas and on cross bar conecting to main hull

    3.jpg

    Once again big thanks
     
  2. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Welcome to the forum! The foil configuration you show in your rendering looks fine-but I wouldn't call it a canard. Those two forward foils would do best if they supported about 80% of the total weight. You probably wouldn't need any kind of roll control-the surface piercing foils will do that automatically. The main hull looks ok -depending on the power you have almost any kind of main hull can be used.
    It's good to have everything adjustable.
    The amas look fine in the rendering but ,if you can, more overall beam on the boat would probably be helpful-especially helpful in turns.
    The two forward main foils will control altitude automatically with speed.
    Good Luck!
     
  3. sub_0
    Joined: May 2015
    Posts: 15
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    Location: Croatia

    sub_0 Junior Member

    yes in our inicial design we putted more weight on aft foil about 70 % at this point we are considering all options , but can u tell me what ll be advantage of putting more weight on front foils . We are trying to make as much pieces adjustable so that will allow us some more room for corecting mistakes . Also whats your opinion on behaviur of these kind of configuration in 90 degrees turn.
     
  4. sub_0
    Joined: May 2015
    Posts: 15
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    Location: Croatia

    sub_0 Junior Member

    as i said you can neglect the dimesions between forward and aft foils cuz upper pic represents our inicial design we didin t take much care drawing real dimensions
     

  5. Doug Lord
    Joined: May 2009
    Posts: 16,600
    Likes: 301, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Pitch control is improved with 80% of the load on the front two surface piercing foils. The foil loading on the trailing rudder foil needs to be less than on the main foils.
    The two surface piercing foil configuration with a trailing rudder foil is a proven configuration.
     
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