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
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Test Model

    Here are some shots of all the foils. The daggerboard, rudder, and the two ama foils have been trimmed, sanded and filled and sanded again to 80 grit. Spraying Duratec tomorrow then the rudder will be attached to the rudder foil and the daggerboard will be attached to the mainfoil, then sanding to 220,320 and 600 and final finishing:

    click-
     

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  2. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    Good work Doug.
    Hand finishing and attention to smoothness really pays off.
    I know a guy who hauls his Corsair 28R out on his home launching ramp and cleans off the hull with auto polishing compound between races. He is always in the top three in the local racing circuit.
     
  3. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    MPX Test Model

    Thanks, Paddy!
     
  4. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    MPX Test Model

    Getting close to the assembly of the main foil to the daggerboard-a very tricky operation:
    1) the flap must be attached to the main foil,
    2) the pushrod(carbon) must be pivotably attached to the flap,
    3) the pushrod length must be double checked so that it matches the "flap neutral" point of the main bell crank(attached to the axle that is attached to dual wands).
    4) mainfoil carbonated and glued to daggerboard. Joint reinforced a lot forming a small "bulb".
    ----
    1-4 must be done virtually simultaneously with great care to avoid getting epoxy in the wrong place! I like doing this kind of detailed stuff......
    ==========
    --Priming all the foils with Duratec tomorrow-that will get them all closer to final sanding and painting.
    -- also working on a stand for the boat to help with set up at the water and to allow precise foil set up here.
     
  5. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Test Model

    Here are the foils(2 ama foils, daggerboard, rudder) with duratec primer applied. Unfortunately, I mishandled one of the ama foils and broke a tiny fragment off the aft outboard corner of the stb. ama foil-very annoying.
     

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  6. Eugene Jerling
    Joined: Jul 2013
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    Location: Durban, South Africa

    Eugene Jerling New Member

    Hi Doug, wow what a cool project. I make fishing kayaks and have plans to develop a kayak with either collapsable and removable outriggers (ama's) and hydrofoils which can be deployed after getting through the surf. We have very heavy swell here on the Bluff , Durban, the reef begins less than 500m from the beach, so our swell comes directly from the pacific. What with the Japanese fishing fleet raping our coast, we need to travel far to find virgin fishing grounds.
    Anyway, your design caught my eye, then this thread flamed my desire, so much so that i joined this wonderful site. Thanks for your efforts, I'll try upload some of my projects soon, but please be patient as I'm talking from a phone at the moment. Thanks again, I'm eagerly waiting further installments. :)
     
  7. Doug Lord
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    Doug Lord Flight Ready

    MPX Test Model

    Thanks, Eugene! Welcome to the forum -your project sounds interesting-good luck with it.
     
  8. Doug Lord
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    Doug Lord Flight Ready

    MPX Test Model-Update Sails

    My sailmaker, Scott Morgan, and I will meet tomorrow when, better late than never, he will start on my sails. Because of the earlier foul-up where the software Scott uses on his cutter was incompatible with the new sail design software, he had to contact Sandy Goodall to redesign the sail using the old software. Since that had to be done, I took the opportunity to increase the area of the main so that total area is 3430sq.in( 24sq.ft )-up from 3182 sq.in.(22 sq.ft). The sail plan is reefable. This results in an increase of wing mast length of 8.5"-from 90.5"(7.54') to 99"(8.25'). Also had to change the head of the main which was a "peaked up" square head to a "normal"(but large) squarehead at 90 degrees to the mast because the old software can't handle the peaked up design.
    Should have the new sails next week(knock on wood).
     
  9. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    MPX Test Model

    Here is a screen shot of the "new" sail(old software) compared to the "old" sail(new software). You'll notice the "new" sail is higher aspect because it is 8.5" taller with more sail area.

    Pictures: Left-"new", Right-"old":
     

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  10. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Test Model- theory continued---

    I haven't discussed this for a while. The T-foil used for the mainfoil on the main hull will be lifting vertically but the boat will have an angle of heel-for light air from zero to 10 degrees, for moderate and heavy air up to 17 degrees for wave clearance of the main hull. This can be achieved with adjustable length wands or manual control of the mainfoil flap.
    But some have wondered if ,at those angles, the lifting main foil might create a leeward component to its vertical lift. The answer is only momentarily and even then-on this boat- that would be countered by the lateral resistance portion of the ama foil*. Since the boat will take off in between 5-7knots of wind, depending on weight, the potential leeward vector of lift will only occur when the boat is heeled at 10 degrees or less and only in the time from liftoff to flap neutral occurring between about 5 knots of boat speed and 8 knots of boat speed. After about 8 knots boat speed the main foil flap will have neutralized the main foil lift and soon thereafter be locked with the flap slightly up or allowed to go up enough to create downforce and a positive lift vector to windward. In other words, the main foil will be unloaded after about 8 knots boat speed with the ama foil supporting 90%+ of the boats weight with the rudder foil supporting the balance. As speed increases, the rudder foil goes first to zero vertical lift then begins to pull down automatically.
    ---
    So the only leeward lift vector associated with the main foil would be at between 5 and 8 knots boat speed after which the mainfoil lift is zero or allowed to develop downforce for additional RM. During that short period of time the ama foil(lateral resistance portion would counter the small leeward lift vector 100%). The beauty of this system is that the main foil and rudder foil automatically unload as speed increases with the main foil either not producing any lift or producing small amounts of lift associated with pitch control, or the mainfoil/wand system can allow the main foil to produce downforce as required. At angles of heel over 10 degrees the main foil is at zero vertical lift or pulling down.
    If the MPX system is used in a "foil assist" application with no leeward foil, then the small leeward lift vector would either be accepted for it's brief duration or countered with a gybing board or canting board. Frankly, the problem only exists for a very short time so , in most cases of "foil assist" the idea would be to get thru the small drag portion of the speed range (upwind only) as quickly as possible.
    *The foiler version pretty much takes care of itself-especially if the angle of incidence of the ama foil is easily adjustable(with the windward foil retracted) which would allow the boat to remain essentially level after takeoff until there is no problem.
    If you have any questions,please ask and I'll do my best to answer them.....
     
  11. Nolan Clark
    Joined: Mar 2007
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    Location: Michigan, USA

    Nolan Clark Junior Member

    Question

    Doug, I'm a long time reader first time poster. I have been following your project for quite some time and I'm excited to see you getting close to wrapping up the build. I understand what you are attempting to do and I am anxious to see the results but in your last post you state "As speed increases, the rudder foil goes first to zero vertical lift then begins to pull down automatically." How is this accomplished automatically? Thanks. Nolan
     
  12. Doug Lord
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Test Model

    ==========
    Hi, Nolan-it's a characteristic of a trailing rudder foil that is set at zero degrees angle of incidence(to the main foils +2.5 degrees). At takeoff the whole boat pitches up slightly so that the running angle of the rudder foil is sufficient for the 20% of the total load it needs to carry.
    As speed increases, the whole boat begins to pitch down due to pressure from the rig. As that happens the vertical lift disappears from the rudder foil(due to the lowering of the running angle) until at fairly high speed the running angle of the rudder foil is very slightly negative, causing downforce.
    It's a characteristic of trailing rudder foils and apparent on the Rave, Osprey, my F3 and on other foilers.
    Hope this helps.....
     
  13. Nolan Clark
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    Location: Michigan, USA

    Nolan Clark Junior Member

    Thank you. Yes I does help. Good luck with the rest of the build and thanks again for all of your explanations in your posts.
     
  14. troy2000
    Joined: Nov 2009
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    Location: California

    troy2000 Senior Member

    As usual, I'm fascinated by this thread; it's a window overlooking an area I know little or nothing about. But although it's far outside my knowledge and experience, Doug does a good job of explaining what he's doing and why.
     

  15. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Test Model

    Thank you, Troy! Getting closer.....
     
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