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

    What I expect out of this test model:



    Fire Arrow



    UPDATED(moved and edited): 5/24/14--. This post will remain within three pages of the end of the building portion of this thread and will be moved and/or updated as required. The idea is to allow anyone really interested to find all the pertinent info on the boat in one place-at or near the end of the thread.
    . Changes will be made every day if they are required and I will try to note them. Numbers 15 and 16 added this date.

    ===============================================
    ===============================================
    These are some "questions" posed by a poster on another forum(with a couple I have added). I think they represent a good idea in that it will allow me to summarize my expectations for this test model foiling trimaran before I sail it.

    1) Will boat tack thru 90 degrees or so upwind? on foils?
    --I expect it will but I also expect that the boat has the potential to tack on foils as well as to gybe on foils. My previous rc foiler design almost did it in relatively light air.
    ======
    2) Will it foil in a stable fashion downwind above a certain True Wind Speed?
    --Yes-above 5-6 knots TWS. The boat should begin to foil at a hull speed of 4.75 mph(4.13 knots). The foil loading and power are better than the F3 that met or exceeded these numbers.
    ======
    3) Much of the the time downwind it should fly on "X" number of foils. And this is the behaviour I expect to see.
    -- It will fly with three foils immersed, one mostly unloaded, one of them carrying about 80% of the load ,the other 20% of the load. After the boat achieves full flight the main wand controlled foil will be near zero lift(except in it's roll of working with the rudder foil in pitch control) with the majority of the load carried by the ama foil and 20% of the load carried by the rudder foil. I expect that the boat will fly at a 10 degree angle of heel with the ama clear of the water most of the time. The boat should be able to foil upwind.
    ======
    4) Should do "X" when it hits a puff?
    --Speed up with little change in pitch and roll attitude.
    ======
    5) Should do "Y" when it speeds up a lot?
    --Generally, the same as #4.
    ======
    6) When it gets upside down ,it will.....?
    --Piss me off... Seriously, I expect the boat to be very stable in pitch and roll so will sail without masthead buoyancy for the first couple of times.
    ======
    7) It will be very pitch stable because.........
    -- Even when the ama foil is fully loaded the wand controlled main foil and the rudder foil work together to control pitch of the whole boat and,therefore, the ride angle of the ama foil. Even if the ama foil was to ventilate, it can't physically pitch down, and the planing ama would pick up the slack(lack of lift).
    ======
    8) Things I am not sure about as a designer include its behaviour in these conditions:
    a. bigger waves-the wand controlled main foil and rudder foil are very deep which should ensure pitch control in most conditions. Just what the conditions will be that exceed "most conditions" will be interesting to learn.
    b. behaviour of the ama foil in near top end conditions- will it ventilate, plane(like a DSS foil) or some heretofore unknown combination of foiling and planing(and ventilating). The ama foil will get critical in it's performance far before the mainfoil and rudderfoil do-thats why they are so deep. The effective range of ama foil performance both in terms of speed and waves is a major element of the testing to be done. I want an ama foil on the full size boat that doesn't require a wand or manual adjustment throughout the entire speed range-thats a big ask. We'll see how it goes.
    c. I want to experiment with the planing ama by changing the ama foil as well as changing the bottom area(but not the volume) of the ama itself.
    d. As the designer, I want to see if the ama foil lifts the weight due to heeling moment from the slowest speed to the fastest speed-do my calculations match it's performance? I have concerns in both areas. At slowest speeds the foil may require something like the spring loaded flap to create enough lift,and at fastest speeds may require something like servo(manual) reduction in the angle of incidence. Generally, on my foilers I set the boat up with the angle of incidence of main foil at +2.5 degrees and the rudder foil at zero degrees. The ama is an asymmetric foil but I am still starting at + 3.75 degrees though that may too much. These angles are measured parallel to the nominal static waterline that starts at the bow knuckle and goes to the point where the center of the transom touches water. However, I discovered that if I tilt the boat(F3) back after setting the foils up as above, she will take off quicker. In about a 5-6 knot breeze the F3 would take off in about two boat lengths when set up this way. We'll see what this thing will do.
    =============================================================================
    Additional questions and comments:
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    9) The L/B ratio of the main hull is smaller than most tris-in other words the main hull is wider. Why do you expect that it will be satisfactory?
    -- The L/B ratio on this hull is close to that of a Weta full size tri and matches a 20' tri I designed and built many years ago. The hull is a planing hull and has about 20% more wetted surface(in seahugger mode) than the "ideal" rc or fullsize race tri main hull has. The model is scaled down from a full size hull I used to have which is the primary reason for the beam. But the most important factor in assesing how this hull will work is the Sail Area/Wetted Surface ratio* compared to my F3 rc trimaran foiler. And this boat has equal to more sail area per sq.in. of wetted surface than that boat does both in seahugging mode and when foiling.
    * SA/WS(with Code Zero)= equal to F3 at takeoff(even with the wide planing hull), better when foiling--7/1 seahugging, 16.5/1 foiling.
    ========
    10) You've said that the projected sailing weight of this boat is 21.13 lb which exceeds your target weight of 16.688lb. How will that affect the performance of the model?
    -- I don't expect it to affect the boat much because the amount of sail area per pound of weight almost equals the same measurement on the F3. The boat has enormous power to carry sail. The affect, if any, may be in very light air, but I don't expect a problem relating to weight and it's actually an excellent test for the ability of the boat to carry extra load. If this was designed from scratch as a racing rc trimaran it could have been built for 11-12 lb. but it is designed as a scale model. At any rate, the boat should be able to perform very well at this loading. I extended the stern of the main hull about 9% to improve pre-foiling take off speed.
    -------
    11) Full size applications in 60-100 footers?
    --After rewatching the MOD 70's and Open 60 tri's under sail I'm more convinced than ever that the wand controlled main foil could be a big aid in allowing not only much better light air performance because of flying the main hull in very light air , but improving heavy air performance by improving pitch stability while also allowing the boat to be pushed harder because the wand controlled(or electronically controlled) main foil can instantaneously develop downforce as a responce to a gust giving more margin(not to mention speed) in tough conditions. In a situation like Virbac-Paprec got into a short while back the main foil might have prevented the capsize. But thats one of the reasons why there is a test model-to see if that is true-which could be a big deal.
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    14) Reefing changed see post 664 for changes. Probably won't affect testing.
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    15) Radio Box changed-see post 664. Will reduce size and weight of box. Makes installation of servos now and later simpler. Still allows for ama incidence control and "manual" mainfoil flap control with mounting of servos at ama and main foil servo on aft deck with wires run to box.
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    16) Did you know: MPX = Max Power Experimental
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    17) See post 1177 for the "bottom job" where the length of the main hull was increased by 5.25".
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    18) See post 1178 for more pictures of the model with the rig on it for the first time.

    ======================================

    -See page 77, post 1155 for references to other interesting posts.
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    Last edited: May 29, 2014
  2. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Test Model

    MPX Test Model Specifications---latest update: 5/9/14

    A) Name- Fire Arrow

    B) LOA-79" (6.58')-including bowsprit

    1. mainhull-66.19" (5.52') (The reasoning behind and the story of the added hull length can be found in posts 1177,1187-88,1195-1198)4/30/14
    2. mainhull+ rudder and gantry(no bowsprit)- 69.125" (5.76')

    3.planing portion of ama=34in. (2.83')

    4.ama LOA=50.75in.(4.23')

    C) Beam-81.6"(6.8')

    D) Mast 103in. (1.75"chord wing mast / 8.58')5/1/14
    E) Sail Area:
    1. Main+ Mast + Jib= 3390.9sq.in.( 23.5 sq.ft.)5/1/14

    2. Main+ Mast + Code Zero=4087sq.in.(28.38 sq.ft.)5/1/14

    F) Foils:

    1. Mainfoil(wand controlled flap)-Span=23.75in., Area=39sq.in.

    2. Rudder foil-Span=19in., Area=29sq.in.

    3. UptiP ama foil(one used at a time,except at takeoff)-Span(from bottom of ama- a surface piercing, soft "L" configuration)=16.5in., Area(from bottom of ama)=45sq.in.; varies with speed and load.(Inspired by the TNZ AC 72 main foil with refinements that allow it to behave as a surface piercing foil with(with or without leeway coupling) a wide speed range that- hopefully- won't require manual angle of incidence adjustment while sailing.)5/1/14

    G) Weight- 21.13lb. 5/1/14

    H) Foil loading at takeoff*(80%= 16.9)=.190lb/sq.in.(F3-.188)(lighter=better)5/1/14
    * windward ama foil+main+leeward ama foil=22sq.in.+39sq.in.+28.125sq.in=89.125sq.in. at takeoff.

    I) SA/Lb(21.13lb displ ) with Code Zero=193.4sq.in.,with main +jib=160sq.in(F3-208.5)(more=better)5/1/14

    J) SA(incl Code Zero) per sq.in. of mainfoil group area(89.125sq.in) at takeoff=45.85 sq.in./per sq.in.(F3-49 sq.in/per sq.in)(higher=better)5/1/14

    K) SA/WS(with Code Zero)= better than F3 at takeoff(even with the wide planing hull)--7/1 seahugging, 16.5/1 foiling.

    ===================================
    ===================================

    MPX FOIL SYSTEM
    --added #6 below 12/8/13 and modified 12/9/13
    --added to #3 below on 12/13/13
    --added f.,g.,h. and i., 5/1/14

    Here is a brief summary of what makes the MPX foil system unique and why that is important:
    1) The boat has four foils total. On the fullsize version, only three foils are used at any one time. On the model, since the ama foils will not be retractable(at least initially), they both contribute to vertical lift at take off with the majority of lift coming from the main wand controlled foil and the lee ama foil.
    ---
    2) Here are the unique characteristics of the ama foil:


    See page 73, post 1090 for much more on the theory that applies to the unique ama UptiP foil. It has just been updated with a link to Dario Valenza's experiments on A Class cats with "uptip" foils where he found that the foil will function w/o leeway coupling for heave stability --using the breaching of the inboard tip for altitude control when leeway is low.



    a. The Uptip ama foil is designed to only lift vertically(no downforce) and horizontally,
    b. The ama foil is targeted to perform throughout the speed range with no adjustment. It is anticipated that the angle of incidence may have to be changed once, as speed increases, if it is changed at all.
    c. The ama foil is designed to carry 80% of the weight of the boat with the rudder foil carrying 20%. The ama foil loads up as the mainfoil unloads.
    d. The ride angle of the ama foil is controlled by the action of the main foil and rudder foil together.
    e. The ama foil was inspired by the new type of foil designed by Morrelli and Melvin for TNZ except that this foil has a wider range of speed before angle of incidence adjustment might be required.
    f. The ama foil angle of incidence of the vertical lifting "L" portion of the foil for the first sail is 3.75 degrees relative to the static waterline.5/1/14
    g. The ama foil angle of incidence of the vertical portion of the foil is set at +2.25 degrees, relative to the boat centerline, for the first sail. This will unload the daggerboard and provide leeway coupling to help with altitude control.5/1/14
    h. The main foil angle of incidence for the first sail is +2.5 degrees relative to the static waterline.5/1/14
    i. The rudder foil angle of incidence for the first sail is zero degrees relative to the static waterline.5/1/14
    --
    3) The main foil has a flap and the flap angle is controlled by a wand*. This allows the boat to fly the main hull in very light air which is a big advantage for an oversquare trimaran-particularly a tri under 20' which would, likely, not be able to fly the main hull in these conditions. As soon as the main hull lifts off, the boat accelerates to roughly twice windspeed in a 5mph wind. As the boat speeds up and heels, the mainfoil unloads as the wand causes the flap to rise. At a certain point the flap causes the main foil to not produce any lift with all the load automatically shifted to the ama foil. If the main hull rises above this point(about 10 degrees angle of heel initially), the flap will continue to rise causing the main foil to create down force(unless this facility is disabled). When the main foil is developing downforce it is also developing lift to weather, similarly to the lift to weather when a Moth is using Veal Heel(except on this boat it is a function of the "normal" heel of the boat and the downforce on the mainfoil). See post 532 for an illustration of how this works.
    * The boat actually has dual wands but they act on a single axle acting as a single wand.The reason for that is to allow the wand to work when the boat is heeled. The lee wand is nearly vertical when the boat is heeled 10 degrees and acts to maintain an angle of heel of about 10 degrees and an altitude of the main hull of about 6". See the sketch below showing the heeled waterlines. Also see posts 512 and 514 for more on the wand system. See page 40, post 597 for a video of the MPX wand activating the main foil flap.
    ---
    4) The rudder foil is a trailing foil that automatically develops 20% of the lift required at takeoff, then gradually unloads until it begins,again automatically, to pull down.
    ---
    5) As best I can tell there is no other trimaran in the world using a foil system like the MPX system. Having a wand controlled mainfoil on the main hull and an ama foil that flies the ama(nominally a few inches above the water) with no control input other than that of the surface piercing component of the foil and the effect of leeway on the "L" portion of the foil(however small) will be significant if it works. The whole foil concept will be significant if it works because:
    a. it allows an oversquare tri to fly the main hull in light air,
    b. it unloads the mainfoil allowing it to become,with the rudder, primarily a pitch control system which controls the running angle of the ama foil.
    c. it allows the mainfoil to contribute to righting moment with downforce,
    d. it allows the mainfoil to develop lift to weather when it is developing downforce.
    e. the deep main foils acting to control pitch prevent the main hull from bottoming out and allow the angle of heel to be varied between approximately 10 degrees and 17 degrees(or a bit more) by adjusting the wand length.5/1/14
    f. the planing ama design serves as back up in rough and/or gusty conditions when the foil might be momentarily overpowered.
    ---
    6) Speed- Top end speed is NOT the priority of the MPX Foil System-light air speed resulting from the unique ability to fly the main hull in light air is. The MPX Foil System's main claim to relevance are the two lifting foils on the main hull which allow an oversquare platform to fly the main hull when a wide trimaran,particularly 20' or under, w/o these foils would not. To make a 1.2-1.3 oversquare tri fly the main hull (without foils) requires excessive sail area(or wind) and impairs the pitch stability of such a boat . The two main foils work together to provide pitch stability way in excess of any "normal" trimaran and control the running angle of the planing ama and ama foil. The system should work well with a planing ama using foil assist and/or using an ama foil that allows the ama to fly when the main hull does(the current test model configuration).5/1/14
    Top end speed is enhanced by the initial configuration being tested which has the light air advantage intrinsic to the system with the added speed potential in heavy air due to the reduced ama wetted surface and the fact that the main foil will develop downforce adding to the righting moment. Further, the foil that flys the ama is designed to support 100% of the boats weight as the boat speeds up, unloading the mainfoil and reducing drag substantially.

    ======================================
    ======================================

    >Preliminary testing has encompassed testing all foils to 3 times their calculated maximum load(estimated 150% reserve above that before breaking).

    > Boat was originally designed as a scale test model of an 18 footer based on a full size hull I used to have(donated to a friend).Since the stern extention it is longer.4/30/14

    >See post 1242 that confirms the ability of my first foiler design(F3), about 15 years ago, to do foiling tacks and gybes!5/9/14
     
  3. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX TEST MODEL---Testing and Development

    Testing and Development







    Design and Building phase is covered in detail on pages 1-87. Testing and Development phase begins NOW.

    >>>> IMPORTANT NOTE: Thanks to Jeff you can go directly to the first page of the Testing and Development section by going to the first post of the thread and clicking on the link near the bottom of the page.






    Testing and Development
     
    Last edited: May 30, 2014
  4. DennisRB
    Joined: Sep 2004
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    DennisRB Senior Member

    Great news Doug! Cant wait to see it going. Don't worry too much if she doesn't do everything you want right way. I am sure it will be awesome once its dialed in.

    Congrats!
     
  5. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    MPX Testing and Development

    =======================
    Thanks, Dennis! I think she'll do fine......
     
    Last edited: May 27, 2014
  6. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    MPX Testing and Development----------Wing Tip Rig

    Almost every production or experimental model I've ever done has featured a version of this, particularly the Flyer 3 trimaran. It wasn't on my "to do" list to complete the boat(but should have been) and won't be used on the first test sail or two because Scott(sailmaker) won't have it for a couple of weeks. But it is relatively important for testing in stronger winds-anytime there is potential for a pitchpole or the remote chance of a capsize because it will prevent the boat from turning turtle.
    The shape will, hopefully, act,to some degree, as a vertical endplate and inside it, on this boat, will be 1.5 lbs of foam buoyancy. The outside will be made from red sailcloth.

    Pictures-L to R-1) MPX Wing Tip Rig, 2) Super Scow with Wing Tip Rig, 3) Flyer 3 with Wing Tip Rig(look closely at upper left side of picture and you'll see Dr. Sam Bradfield standing there. Gives an idea how large this model was), 4) Red Flyer 3 with Wing Tip Rig :
     

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    Last edited: May 28, 2014
  7. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Testing and Development

    =================================
    Finally talked to Tony and he said it was no problem-the noise is typical of digital servos . So it's a green light to go sailing.......
    click-
     

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  8. warwick
    Joined: Jan 2012
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    warwick Senior Member

    Sounds good for you Doug, go have some fun now.
     
  9. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    MPX Testing and Development

    =====================
    Thanks Warwick. We still have a wind problem here 9-10knots every day. Too much for the first sail. June, July and August are usually calm in the morning with the seabreeze coming in about 1 in the afternoon.

    ---------------------------------------
    >>>> If anyone knows anything about music licensing maybe you could help me answer this question: http://www.boatdesign.net/forums/al...on-use-music-boat-video-50524.html#post689904
    ---------------------------------------
     
  10. redreuben
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    Location: Beaconsfield Western Australia

    redreuben redreuben

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

    Doug Lord Flight Ready

    MPX Testing and Development

    Opened up the Go Pro and the igotU GT 120 "USB GPS Travel and Sports Logger" for the first time today. The GoPro has a nice little manual and the data logger has a disc as a manual-a very small disc about three inches. And I've also got a Davis wind meter. Got some reading to do...
    UPDATE: should have opened the tracker a long time ago: the disc supplied containing the manual is only 8 centimeters whereas my computer only supports 12 cm discs! I've written to the tracker mfg to get another disc or a hard copy of the manual.
     

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  12. nzclipper
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    nzclipper Junior Member

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

    Doug Lord Flight Ready

    ========================
    58 is the best surface piercing foiler I've seen yet!
     
  14. Darth Reapius
    Joined: Mar 2014
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    Location: Australia

    Darth Reapius Junior Member

    Doug, what sort of drive do you have?
    If it is a center "click in" drive, any size will work fine, and if it is a "retractable tray" check because as much as the main tray is larger, the tray might have grooves in it that will be the size of that disc, and if you put the disc in the grooves it will be fine, any CD player should be capable of playing mini and micro CD's
     

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

    Doug Lord Flight Ready

    MPX Testing and Development

    =================
    DR, this is an XPS M1530 Dell and I have the manual: it specifically says only
    12cm discs. I'll get thru to the igotU manufacturer one way or the other. Thanks.
    Do you know anything about Go Pro cameras? Or Speed Pucks? I have a brand new $350 speed Puck with no manual or instructions whatsoever but I may be able to figure it out if I spend some time fooling with it. I have a working Garmin GPS that I may strap to the boat to get speed. The Speed Puck was bought for the Crossbow fl and is too heavy for the model. The little Data Logger is supposed to give accurate speed. Worse case I'll measure off 100' and time the damn boat!
     
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