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

MPX-ama foil -Curved "L" foil

This is a working sketch of the ama foil at max deployment. Much easier to build than the "bent T-foil"(post 231). I'll be able to manually slide the board up for transportation or to experiment with the different configurations that emerge as the board is pulled up. I don't think I'll have to make the board slide up or down by radio. I may have to adjust the angle of incidence by radio but I doubt.
If you look closely at the sketch you'll note that the static waterline(where the water touches the foil when the boat is sitting level and not moving) and the flight waterline are the same!(bottom of ama 3"(11" fullsize) above the static and flight waterline). True of the ama only. What will happen as the boat starts to move is that this foil will begin to lift more and more of the boats weight and the main hull will fly with the bottom 6-7"(1.8'-2.1' fullsize) above the water. To start, both ama foils are partially immersed at the same level they will be when one of them is carrying the whole load. If the wind/apparent wind increases perfectly smoothly the distance of the ama above the water won't change much for 0-10mph+ boat speed(model)! Of course ,on the full size boat you'd probably have the ama foils mostly retracted in very light air.
The dihedral angle of this boat is substantially greater than most trimarans you have ever seen promarily due to the "curved pieces" that have been explained earlier. The dihedral will help with the self-righting aspect of this boat(NOT being tested initially) Also the bottom of the very small amas will be almost one foot above the water with the boat level and not moving. Because of the wide beam(22' for an 18 footer) when the ama bottom touches the water the angle of heel of the boat will be only 5 degrees. Nominal angle of heel when the boat is sailing is 10 degrees with main hull and ama flying.

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Multihull Performance Xperimental / SRT

Final set up of boat:
1) Flight altitude:
a.mainhull--6" @ 10.5 degrees
b.mainhull--8" @ 13.5 degrees
c. ama-static and dynamic nominally 3"
2) Dihedral= 10 degrees

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SRT /MPX Test Model

Here is the final sail plan:
--Mast Height off water=93.5"( 7.8')
--Main=2039sq.in.
--Mast= 174sq.in.
--Jib= 625sq.in.
Total SA= 2838.6sq.in(19.7sq.ft.) Max Pressure full rig=.48lb per sq.ft.
SA/lb=2838.6/ 13.5 total sailing weight= 210.2 sq.in per lb..
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Reefing system-Max RM=38.07 ft.lb( no downforce from main foil*)-Max HM=MaxRM:
1-Remove jib= 15.37sq.ft. @ Max HM=.56lb. per sq.ft. pressure
2)Remove jib and roll lower panel of main; lower main=11sq.ft. @ Max HM=1.15lb.per sq.ft. pressure.
--NOTE: the usable range of each level of sail area can be extended by depowering the rig, probably up to 30%-40%.
* downforce is possible particularly in gusts

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MXP-SRT-test model

This week:
1) Pick up styro "molds" for the new style curved "L" foils,
2) Drop off the sail plan at Sails by Morgan,
3) Do "cosmetization" of main and amas in prep for:
--a. bonding curved piece to ama
--b. carbonated curved piece and ama/curved piece joint,
4) Cut carbon crossarms, add ferrules and antirotation device to each one.
This will allow the amas to "unplug" from the main hull and still retain their torsional stiffness.
5) Do layouts of daggerboard, rudder, main foil and rudder foil.

 

Sounds good. Keep on plugging away at it.

 

MPX test model

Thanks, Paul. Spending a lot of time on it and progress should continue to be good, I hope.

 

Where do you get molds? Can they make full size board molds from coordinates or CAD? Are they accurate?

 

MPX test model

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The foils will be built in quickie molds(made from styro, balsa, carbon in various combinations). The amas and main hull were built of balsa and carbon(as you can see further back in this thread). Every component is hand finished.
All of it is designed and built by me except the mast where I talked Forte into building it much thinner than their normal spreader and the sails where I draw the planform and do the calculations and Scott Morgan builds them.
I design and build the foils using a section and planform that was successful on my production foiler, the F3. Sail area and foil loading is also based on the F3 or improved from there. The main foil and rudder foil are symmetric sections of 9% t/c ratio and a tapered planform. The ama foils will be asymmetric and fairly difficult to make at 9%. Ama foils are 100% carbon and daggerboard and rudder will probably be carbon and wood with the main hydrofoil and rudder foils 100% carbon. The main foil will have a 30% flap centered as in the foil in the picture below. The foil is fairly thin and having the flap extend fully spanwise would be a mistake that could lead the the flap jamming. The center partial span flap works well.

Pictures: F3 foiler and typical model type foil...

 

Ok. Since you said "pick up styro molds" I thought you had them CNC'ed.

 

Doug,

What about less talking about and more doing it please. I reckon they built the Titanic in less time than this has taken. 19 pages is just a tad excessive - no?
I just want to see how this thing goes

Bas.

 

Mpx/srt

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Well, the "molds" are computer cut from my plan at an architectural foam business. But they cannot cut the section shape-I have to do that by hand.

 

MPX/SRT test model

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No, I don't think it's excessive-it's detailed but not excessive, in my opinion. Did you read it all? I will continue to update progress frequently and in detail.......

 

34th AC

Took the sail plan by the sailmakers today and we decided to have Sandy Goodall do the design on the main; Scott will do the sail design for the jib.
The design work that will be done is within the framework of the sail planform design which I did. Mr. Goodall offers his services as a consultant and Scott has used him for years. His help on the big square top main will be valuable.
They'll be ready by the first of April. My camera died today so I can't show you the material but it is Dimension Polyant ODL04.
Here is what the material looks like on a International 2.4 meter: http://news.dimension-polyant.com/en/newsdetails/dimension-polyant-sailcloth-odl04-2/
More on the ODL material:

Designed to absorb a wide variety of loads often seen in One Design sails the One Design Laminates are produced with Technora® Black in the warp and fill achieving an unmatched strength and durability. With the extra wide X-PLY® angle of 22° and Technora® Black as X-PLY® material this line is the ultimate in high performance One Design Laminates.

Features of One Design Laminate-Line

•Very low stretch
•Outstanding shape holding durability
•Grand Prix sail - scrim version
•Extra Wide X-PLY® for One Design

 

MPX-SRT camera

My wonderful 7mpx Z712 IS camera is dead. Whats even worse is that Kodak is out of the digital camera business and only honoring warranties that haven't expired-no repairs. So because I need a camera I ordered a Olympus 4GB 16mpx 10X opt zoom camera for $99. Should be here in 3 days.
All the pictures in this thread were taken by the little Kodak......

 

MPX/SRT test model

A note on the gantry: what this thing does is get the rudder hydrofoil further aft increasing the footprint of the foils which results in an increase in pitch stability particularly on this boat with the main foils unloading.
The gantry will be adjustable over a range of about 6" in order to document just how effective the aft position is compared to the forward position.

gantry illustration-click- smaller model illustrating retractable gantry :