High Performance MPX Foil/Self-righting Trimaran-The Test Model

Discussion in 'Multihulls' started by Doug Lord, Dec 28, 2010.

  1. Doug Lord
    Joined: May 2009
    Posts: 16,372
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    Location: Melbourne, Florida

    Doug Lord Flight Ready

    WOLF daughter of fire arrow

    Latest Update 5/15/19---Design 99% complete--ready to build!
    Design by Doug Lord--- with a little help from my friends
    Inspired by Fire Arrow
    System usable on trimarans from one meter LOA to 100+'.
    A) WOLF specs(tentative) :
    LOA 15' 8"
    Max Beam 16'
    CL ama hull to CL ama hull-14'
    Target weight 175-190lb
    SA-(mast length 24' all carbon wing mast)
    --upwind: 185 sq.ft
    --downwind: 300 sq.ft
    --max pressure before depowering/reefing:
    -----UptiP Foils= 1.34 lb per sq.ft. sail area.
    -----Welbourn Foils= 1.8 lb per sq.ft. sail area.
    * NOTE-see "F)" below for max pressure comparison with an F18.
    SAIL LOADING- an indicator of hydrofoil performance. Divide weight in pounds by SA in sq.ft( reference: Moth= 2.86lb. per sq.ft. sail loading w 180lb crew).
    WOLF- upwind SA 185, downwind SA 300. Weights using highest estimated boat weight* + 220lb for one person and +340lb for two people(MAX).
    * 190lb
    upwind-one person=2.21 lb. per sq.ft. sail loading @ 410lb total flying weight
    two people=2.86 lb. per sq.ft. sail loading @ 530lb total flying weight
    downwind-one person=1.37 lb. per sq.ft. sail loading @ 410lb total flying weight
    two people=1.77 lb per sq.ft. sail loading @ 530lb total flying weight
    B) Advantages:
    1-Singlehander- Excellent upwind and downwind performance with 220lb crew. Minimum crew weight 120lb*. Two people for daysailing-max about 340lb.
    *Righting moment supplemented by mainfoil downforce.
    2- Will foil in 5 knots of wind with 220lb crew .
    3- Carbon rotating wing mast, carbon cross arms and carbon foils.
    4- Retractable foils(from cockpit). Mainfoil retracts flush with bottom and tips are designed to not dig into sand. Rudder foil retracts above bottom. Ama foils retract above waterline when boat is level.
    5- Extremely comfortable sliding seat* on each side. Allows crew to move 1.75' outboard very quickly.
    * see picture below-
    6- Uses the Fire Arrow Foil System(like Fire Arrow, Gitana 17, Banque Pop, Macif , Macif jr(24'Diam tri) and Maserati)-- the same as the original system first used on the Fire Arrow Test Model- except the larger boats use two rudder t-foils on each tack. WOLF has two UptiP ama foils-one used at a time-and one wand controlled mainfoil for very early takeoff and capable of substantial downforce- all working with a single rudder T-foil. Downforce can be virtually instantaneous adding RM in response to gusts. UptiP foils stay down-no adjustment when tacking or gybing.
    (see #16 below)
    7- Foiling throughout the wind range -including very light air-the essence of 3D SAILING!
    8- Assy Spin/Screecher retracted under the front deck.
    9- Boat folds from max beam to trailerable width in about 4 minutes. No waterstays.
    10- Mid (wish)boom mainsheet so sheet* is always in forward hand and extension tiller always in aft hand.
    *uses variation of the Swift Solo main +jib sheeting system=single sheet.
    11- Quickly self-draining cockpit-large scuppers with backflow flap.
    12- Planing ama hulls designed for incidental contact with water at speed and for inadvertent contact at slow speed.
    Adjustable angle of incidence of planing surface of each ama simultaneously on prototype. Angle of incidence of ama foil has to be changed when this is done. Planing surface starts at +4 degrees.
    Uses Two-Stage Amas-see attachments below. They consist of a planing ama hull(Stage One) coupled to a "curved piece"(Stage Two) that provides extra buoyancy in the event of a knockdown. Curved piece facilitates high dihedral crossarms which keep the crossarms clear of the water.
    13- Planing main hull.
    14- Aerodynamic surfaces added to forward and aft crossarms. Adjustable flaps added on rear cross each side. Jib foot and forward part of main foot to be sealed to deck.
    15- Automatic Foiling: no foil adjustments required after shoving off the beach and lowering the foils.
    16- Adjustable crossarm dihedral for prototype to facilitate testing.

    C) ---Memorable quote from JG Baker, Designer and Builder of the Monitor foiler in the 1950's:
    " The main need is to lower the wind velocities required for flying in order to increase the opportunities for high speed travel"

    D) ---VPLP on the daggerboard main foil:
    " On these big boats, when you ease a sail, it is a pain because it takes so long to grind it back in. But here you press a button and the angles of incidence change. And with the foil on the daggerboard you can use it to alter the flight according to the wind*. If it builds, rather than easing the sheet you increase the righting moment by increasing the angle and conversely, as it eases you can reduce it and let it fly more."
    * done 100% automatically on Fire Arrow/ WOLF with wand controlled main foil.

    E) --- Fire Arrow Foil System-first of its kind on any trimaran. Elements developed first by Fire Arrow include:
    1) the first trimaran in history to use UptiP* ama foils,
    *invented by Team New Zealand
    2) the first trimaran in history to use a single wand controlled main foil capable of downforce,
    3) the first trimaran in history to use Two Stage Amas.(see below for Two-Stage Ama pictures)*

    F) Max pressure for F18 and WOLF before depowering or reefing :
    1)-The max pressure for an F18 based on 229 sq.ft. upwind SA, CE at 16.9', 2-180lb crew on trapezes and 5320 ft.lb. RM is 1.39 lb/sq.ft..
    2) --UptiP Foils-Max pressure for WOLF with 185 sq.ft. upwind SA, CE at 14', one 220lb crew sitting in a comfortable sliding seat, and 3486 ft.lb RM* is 1.34 lb/sq.ft..
    3)--Welbourn Foils- Max pressure for WOLF with 185 sq.ft. upwind SA, CE at 14', one 220lb crew sitting in a comfortable sliding seat, and 4654 ft.lb RM* is 1.8 lb/sq.ft..
    Note: Welbourn foils provide 1.34 times the RM possible with UptiP foils*.
    *not including downforce automatically generated by the wand controlled main foil.
    corrected 5/15/19
    G) *The Two Stage Ama Design offers a lot both Statically and Dynamically:
    1-Statically- the boat is sitting still and hit by a hand of God gust. It is theoretically possible that the boat could be knocked over with the mast horizontal but the two stage ama offers reserve buoyancy after the ama hull itself is immersed by the immersion of Stage Two("curved piece") . It is enough, however, to right the boat and/or prevent a 90 degree capsize.
    2-Dynamically-the ama hull has two levels of dynamic vertical force:
    a. first and foremost the ama lifting foil that works from very low speed on up,
    b. Second, and a sort of back up at speed, is the planing hull design of the ama. To start with on Fire Arrow/WOLF, the planing surface only comes into contact with the surface at very low speed with the ama starting to fly before the main hull does. And when the boat is flying the ama performs as reserve lift during incidental surface contact at speed.
    *Also see here for more on two stage ama theory: High Performance MPX Foil/Self-righting Trimaran-The Test Model https://www.boatdesign.net/threads/high-performance-mpx-foil-self-righting-trimaran-the-test-model.36058/page-191

    [​IMG] [​IMG]
    UptiP Ama Altitude Control-pictures A & B----
    Note that the ama is flying before main hull-note ama flight altitude:

    Now that the main hull is flying and speed and load are significantly greater than in "A" above, note that ama flight altitude is the same! And that's due to the ama UptiP foil design(no moving parts) :



    WOLF Trimaran Foiler -update 5/15/19
    Last edited: May 18, 2019 at 4:53 PM
  2. Doug Lord
    Joined: May 2009
    Posts: 16,372
    Likes: 279, Points: 93, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    Control of pitching with the Fire Arrow Foil System and the nearly identical foil systems on Maserati, Gitana 17, Macif(and Macif jr) and the former(and new) Banque Populaire:
    The Fire Arrow Foil System and the similar systems on Maserati and the Ultims use an uptip(angled "L" on Maserati that works like an uptip ) ama foil with virtually automatic altitude control , and an adjustable mainfoil on the mainhull capable of vertical lift and downforce.
    The big ocean going boats all use two rudder T-foils in the water(3 total). The rudder t-foils and the mainhull foil work together to control pitch giving substantially greater pitch control authority than a tri with just one or two rudder t-foils only (or none at all). However, on the big tris(Ultims), because of a Class Rule, the mainfoil and rudder t-foils can only be adjusted by manual control input- for the time being. Still much better than a tri without these foils.
    But the Fire Arrow (and WOLF) use an automatic surface sensor(wand) to change the effective angle of incidence of the main foil to create vertical lift and/or downforce instantly as required. The mainfoil on Fire Arrow(WOLF) working with the single rudder T-foil controls the flight altitude of the main hull, the pitch attitude of the whole boat(including the ride angle of the lee ama foil) and the angle of heel of the whole boat. The rudder t-foil is a trailing foil that automatically follows the lead of the mainfoil with no manual adjustment necessary. The rudder t-foil automatically adjusts from lifting about 20% of the boat at takeoff to providing downforce as the boat speeds up and slightly pitches down.
    This system on WOLF will make it one of the easiest to sail and safest foilers available.
    Last edited: May 15, 2019 at 2:19 PM
  3. Doug Lord
    Joined: May 2009
    Posts: 16,372
    Likes: 279, Points: 93, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    More on downforce-a previous article. I want to add that one of the best things to happen to me in my quest to learn about hydrofoils was meeting Dr. Sam Bradfield. He befriended me and taught me about wand systems which led to my design and building of the first rc production sailing foiler in 2000(the F3) and to the unique "Fire Arrow Foil System" . A version of the Fire Arrow Foil System is now used on four large tri's and, in my opinion, is the most significant foil system ever used on large trimarans like Maserati, Gitana 17, Macif,(and Macif jr) and the old and new Banque Populaire.
    While the big boats are restricted by Class rules from using all the advantages of the Fire Arrow Foil System(they must use manual input for main foil adjustment) the Fire Arrow and WOLF are not subject to such restrictions thanks to what I learned from Dr. Bradfield. These two boats use a wand surface sensor to control the main foil flap which in turn controls the angle of heel of the whole boat, the flight altitude of the main hull, the pitch attitude of the boat(as in previous post with the rudder t-foil), the ride angle of the lee uptip foil and allows the mainfoil to generate downforce which creates more righting moment as required due to increases in wind or even transient gusts. The system is fast enough to respond instantly to wind gusts!
    So, one more time: thanks Dr. Bradfield!!!!

    Previous article:
    ---------------- -------------------------------------------
    Fire Arrow Foiling System Testing and Development

    Boats like the Rave, Osprey and Hobie Trifoiler (as well as the Whisper and S9*) all have dual ,independent altitude control systems(wands) and are designed to utilize downforce from the windward foil to add to righting moment. Most wand systems are adjustable so that downforce can be varied from a reduction in lift on the windward foil to full on pulling down of the foil.
    The main foil on the Fire Arrow acts like the windward foil on these boats and can develop downforce when required.

    * Both the designer and one of the US owners confirmed the use of downforce on the S9. The builder of the Whisper confirmed to me that it utilizes dual wand controlled SYMMETRICAL foils with flaps which means it can generate downforce when required. All dual, independent wand controlled multihull foilers are capable of generating downforce when required. The fact that they all use symmetrical foils is a clue: if not for the ability to generate downforce asy foils would be the logical choice. Symmetrical foils are used to facilitate downforce.
    added 5/16/19: The S9, Ifly, and Whisper all use dual independent wand based foil systems but they are not exactly similar to Dr. Bradfields system used on the Rave ,Osprey and SKAT. The major difference is that Dr. Bradfields system relied on widely separated foils so as to reduce the drag associated with developing righting moment.
    Another difference on the S9 and I Fly is that they use a forward mounted wand which introduces pitch changes into the wand response (like a MOTH) whereas the Whisper uses a midship-wand as did Dr. Bradfield.
    The new boats use a foil system supplemented by movable ballast(crew) rather than relying entirely on the foil system for RM. This reduces drag that would be excessive due to the relatively narrow spacing of the foils but still allows the foils to supply back-up RM when necessary.


    Greg Ketterman on the use of downforce on the Trifoiler:

    "Hydrofoil boats can be categorized into two categories; 1) Incidence controlled hydrofoils* and 2) surface piercing hydrofoils. The difference lies in the way the boat maintains the proper altitude above the water surface. A surface piercing hydrofoil boat maintains proper height by varying the amount of foil submerged. The boat raises up as the speed increases and reduces the amount of foil submerged and therefore the lift. The boat finds equilibrium at the proper altitude. An incidence controlled hydrofoil sailboat has a mechanism that controls the angle of attack of the foil to maintain the proper altitude. It is generally believed that surface piercing is simpler, but incidence control is more efficient. In reality, it is the method that works with fewer problems that is simpler.
    From the beginning it was felt that incidence control was better suited for a sailboat even though most of the existing hydrofoil sailboats were of the surface piercing type. There are many advantages of the incidence controlled foils; however, the most important is what I call the DLA (dynamic leveling affect). This is the increase in righting moment or stability due to the ability of the windward foil to pull down. The DLA has little affect on the low wind performance, but it essentially makes the top speed of the boat limited to the strength of the boat. Conventional boats with a finite amount of righting moment can only extract so much power from the wind, but with the DLA, the righting moment is virtually unlimited.
    Intuitively many people think that the added drag of the windward foil plus the increased induced drag of the leeward foil would offset the gain in righting moment, but calculations show and practice proves otherwise. The dynamic leveling affect not only produces a dramatic increase in top speed, but is also responsible for all the other key features that this stability provides.
    The other major advantage of the incidence controlled foils is they are less affected by the waves and other surface affects. Drag and losses associated with the surface are the major reason incidence controlled foils are more efficient.
    All hydrofoil sailboats have problems with ventilation; however, surface piercing foils have larger problems, because the foils are piercing the surface at a smaller dihedral angle which makes it easier to ventilate."


    * On the Trifoiler the entire foil was moved to control RM, lift and negative lift hence the term "incidence controlled foils". On the Rave the incidence was generally fixed at +2.5 degrees for the main foils though some owners found a way to decrease the incidence on the windward foil. Lift and negative lift on a Rave foiler is generated by the wand (designed by Dr. Sam Bradfield), a surface sensor(dragging in the water) and attached directly via linkage to a flap on each main foil. The wands are independent just like the trifoiler "incidence controlled" foil sensors.


    Jim Brown article and interview with Dr. Sam Bradfield:

    "For very high speed aircraft, and now for hydrofoils, “symmetrical” sections – cambered both top and bottom – (convex/convex) are used by Bradfield and others. When fitted with an articulating aileron or flap, these foils can create lift in either direction, up or down, and so can exert a profound stabilizing influence on a sailing trimaran. Heeling effort in the sails, which would normally depress one side of the craft and elevate the other, is resisted absolutely by the downwind foil lifting up and the upwind foil pulling down. The craft stays dead flat, the mast stays plumb vertical, the usual spilling of wind from heeling is converted instead to thrust, and the power of the sails is fully utilized to propel a craft that is now largely relieved of the age-old drudgery of hull drag."

    F3 foiler.jpg F3 from rc groups.JPG

    Fire Arrow:
    Last edited: May 17, 2019 at 5:02 PM

  4. Doug Lord
    Joined: May 2009
    Posts: 16,372
    Likes: 279, Points: 93, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    Fire Arrow Test Model-early pictures:
    MPX-assbld_seats_painted_6-1-13_005.JPG MPX assembled 2 008.JPG MPX Fire Arrow.jpg
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