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

MPX Test Model

One thing needs to be reiterated: at this point in time, to the best of my knowledge, there is no full size trimaran anywhere on the planet using this foil system. The primary innovation of this system is a wand controlled main foil on the main hull of a trimaran(with a trailing rudder foil) used for the first time in the history of mankind in this design(and the MPX 12 design) and will be tested for the first time on this model. The test model also includes, but is not dependent upon, a planing ama with a unique ama foil. However, the basic concept can be used on any trimaran with any type of ama though it will work to it's full measure on an oversquare trimaran where it's advantages cannot be beaten. An oversquare trimaran designed as a foiler(MPX) is the highest performance application of this technology.
The concept was originated in 2008 and was first published here in 2010 in another thread. The model design was started in very late 2010* and early 2011(see the first posts of this thread) but very little was done until 2013 and since February of 2013 90% of the model has been completed part time with REAL LIFE work requirements taking first priority. Toward the end of 2013(Oct-December) and extending into this year severe medical issues have slowed work on the boat to a crawl or less.
For those that impugn my belief in this concept due to the time it's taking to complete the model-you should be ashamed of making such a judgement about something you know absolutely nothing about!!!! There are other more appropriate words but I'll leave them for some other place and some other time.
Further, I have received 4 letters patents over the years-all expired- and have developed many patentable devices and I know for an absolute fact that this concept could be the subject of several patents. But I made a decision early on to forego any patents and that I would publish every detail of this system in the interests of furthering the technology and in the hopes that others would see the value in this fantastic concept.
A lot of doubt will fade away when the first video's are published here. I'm considering starting a new testing thread and I asked Jeff about it and he left the decision up to me. So, the fun starts when this thing is complete!
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A mention must be made of Curtis Luxton's RC model. This is a brilliant young man who is building his first(I think) RC multihull and is using a similar concept to the MPX foil system except that the main foil is controlled manually via radio(one thing mentioned in this thread that I will test as well).
Curtis may sail any day now......
wording corrected 3/4/14

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*2010, pgs 1-----2011,pgs 1-13-----2012,pgs 13-16-----2013,pgs16-58-----2014,pgs 58-69+

 

MPX Fullsize Hull Changed---

I just donated the main hull I've had for years to a friend in need(my sailmaker) so that means that the full size version of the test model will not use that hull.
It would be at least three years from now before I could do a full size version of this boat, if ever. I have tentatively decided that if the foil system works, as I expect it to, I will try to do a full size tri using the foil system after I get the Crossbow fl done, but it will be a smaller version based on a hull design I did in 2012. At that time I built an EPS model of the hull.
LOA 15.5'
Beam of hull at wl= 1.71' (9/1 L/B vs 6/1 for original hull).
Tentative SA 200 sq.ft. upwind.
Approx. 165lb all up.
Tentative overall beam-17', folding carbon tubes(or plug in).
MPX foil system
Designed as a single hander with the primary building consideration being that the 4 major EPS components could be cut out by the Architectural firm I've used many times. The hull shape is based on that consideration100%
and produces parts that are 99% ready for carbonation after they are cut out.
As a matter of fact the idea was to glue Dragon plate carbon sheets to the hull after adding structural reinforcement which would produce a hull that has a glossy carbon finish with no further fairing or sanding required. If I could find someone that has a glass table(window glass) I would have the sheets laid up which would be less cost and equal finish to dragon plate. Any part of the hull in direct sunlight would have to be painted white so as not to melt the EPS.
Here are pictures of the model:
click for better view--

 

MPX Test Model Thread-------

Thanks to Jeff for your efforts. And thanks to the rest of you guys for helping
to keep this thread alive-and my spirits up.

 

I have found parts a bit repetitious, how ever I realize it is your way of doing things Doug and it is you who is doing the hard work not us. There probably some who would like it to fail as well, not naming any one.

 

My Boat

Hello everyone,

Doug has mentioned my boat a fair bit on this forum so here's some information and pictures.

I had a bit of a chance to work on it Yesterday- I fixed my cross beams and finished the mast mount/ rig base. Here are some pictures of the boat 'assembled' (I just rested everything in more or less the right spot- the float hulls are too far back.

Maybe this will give you a bit of an idea of what my design looks like. 70% of my knowledge about the foils and their set up has come from Doug and he deserves a lot of credit for helping me with that becuase without his help I don't think I would be nearly as far through this as I am now!!

The foil set-up is similar to the Mpx, there are 4 foils in the water at takeoff -Main foil (servo controlled flap)
-2 ama foils- surface piercing V's on each side (not like Ian's)
-rudder foil at 0 degrees.

when foiling it should fly on the main and 1 ama foil. They support 75-85% of the weight. The main foil can override (create more down force) the ama foils in heavy air to prevent ventilating if need be.




Any comments/ideas are welcome!!

-Curtis

 

Curtis, if you haven't done the ama foils yet you might want to try to avoid an acute angle between the daggerboard and lifting foils.
Notice how these Laser foils are designed: the daggerboard leading edge is substantially aft of the leading edge of the surface piercing foils. The basic concept is an excellent idea as long as you don't have too much wetted surface in the vertical struts combined with the daggerboard.
Boats looking good! Question: are the ama foil struts and the daggerboard sections parallel to the centerline?

illustrations-Laser and rough sketch:

 

Vfoils

Hi Doug, I was planning on making the foils with about 60-65 degrees between the dagger board and foil but I can put a small bit of straight section on either side (about 2cm each) that will probably help me mount them too.

I'm not at the stage of aligning hulls/ daggers etc. yet, I just put them on the stand that I made to show how close it is to being together. I was planning on having the daggers inline with the AMA hull center-line though, not necessarily parallel to the man hull.

I have no idea whats best but I read a bit about it on another forum and I'm pretty sure they were saying to have about 3 degrees of toe in on the amas

I think that is related to the cant of the AMA hulls too and the designed heel angle, I only want the boat to heel 3-6 degrees before takeoff- just enough to have the windward AMA hull out of the water.

Thanks for the foil info, The W/S should be fairly low though, the chord on my AMA daggers is just over 3cm (1 and a bit inches) which isn't much and the foil chord will be around 3.5cm. the AMA dagger length is about 15cm so there's about 90cm^2 (35in^2) of W/S from the AMA dagger fully submerged. and there is only 100cm2 of w/S from the AMA foils them selves. all in all I'm not to worried about that, so long as it foils then I'll be happy. Mach 2 will be way more refined!!!

What is the reason for the foils to be a lot further forward than the dagger-board leading edge? Is it just efficiency from the lift getting turbulence around that area?

Thanks again
-Curtis

 

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Curtis that is just another viable solution to the acute angle problem, by moving the ama board intersection with the foils aft the problem is solved,as best I can tell.

 

Ok, Thanks Doug, I can see the logic in that. I'll probably do it because it'll be easier than making different sections of the foil and putting them together.

 

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Seems like a simpler solution.....

PS-from the pictures it seems like your ama struts are angled forward-is that right? If so what is your thinking?

 

Curtis, the reason for offsetting the bottom foil like a Moth is to lessen the turbulence at the foil junction which creates induced drag.

 

Here are a couple of pdf's worth looking at: Beavers Moth study where about 1/3 to 1/2 of the daggerboards have the leading edge lined up with the leading edge of the foil, but 100% of them use a sort of "bulb" to reduce drag.
The other is Mark Drela's design of the forward rudder on decavitatior ,where the rudder is substantially aft of the leading edge of the lifting foil.

Pictures,L to R,- 1 & 2 MPX rudder foil, 3,4 & 5- MPX Main Foil, 6-MPX Rudder Foil, 7- "Bulb" for Mirabaud-- 30' monofoiler with bi-foil arrangement. 8-Mirabaud sailing, 9- Mirabaud rendering wing + jib:

click for best view--

 

MPX Test Model

According to the forcast Sunday(3/9) is a likely day for me to get the rig up on the boat for the first time. So very close......

 

Hi Doug, That's great that you'll be able to set up the boat!!

Would the bulb on the joint between the dagger and foil be enough (in my case) not to have to worry too much about the angles/ having the leading edge back. I'm was going to have a bulb of some sort on the CB and rudder anyway because it will allow me to "slot" everything in from each side.

What do you think?,

Curtis

 

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You need to offset the daggerboard leading edge and have the bulb-copy the deavitator bulb and try to de-emphasize the acute angle's where the foils intersect the bulb. See sketch below-be sure to click for larger view: