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

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What does this mean?

 

MPX Test Model

Sails, Foils, hulls-it's coming together. I've been off for most of two weeks so they'll be intensive work for the next few weeks. Have designed a large box( 9.5' X 3.5' X 3') and am getting a quote from "The Wood Shop" here locally. It won't be fancy but will allow the boat to be transported and stored assembed.*
*the amas will be removed since it is so easy to do so and that allows the box to be smaller. I won't have to dissassemble the main foil, wand system and rudder components to transport. The sails will stay on the rig or layed out flat on it.

 

Looking forward to seeing it on the water Doug. (Or should that be over the water )

 

MPX Test Model

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Thanks, Paddy! Me too----

 

It's a joke Doug, a play on words after Daiquiri's low pass filter post. The wand is a stick hence we have the no go pogo stick -meaning they don't bounce. Those hop up and down contraptions are pretty obscure these days.....The wording does sort of reflect Walt Kelly's Pogo comic strip when they had the campaign with i go pogo logos (sorry). Also obscure......

 

MPX Test Model

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Curtis, did my answer in post 543 help? Don't hesitate to ask any further questions....

 

Foil system

Hi Doug.

I think so, to recap from my understanding this is what happens...

as the boat accelerates the main hull is flown early, as the boat begins to heel more (between 10 and 17 degrees) the wand on the windward side comes out of the water causing the main foil to create down force and therefore more righting moment while the leeward float hull foil is pushed in more creating more lift there. this causes the boat to level out and fly flat.

I think that's what happens in your system but I may have misinterpreted something.

Thanks
-Curtis

 

MPX Test Model

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Curtis, the windward wand coming out of the water simply reduces drag slightly. If the boat heels(main hull lifts) beyond the zero lift point of the main foil flap AND if the boat is set up to allow it, the wand will move the flap up as the boat continues to heel and that will generate downforce(extra RM and a windward force vector similar in that respect only- to Veal Heel on a Moth). The greater speed of the boat creates more lift on the ama foil and the boat flys at a small angle of heel(set by the wand and /or controlled by sails). Speed increases lift on the ama foil and lift on the mainfoil is created or reduced by the flap position. And force on the rig determines what the wand will do since it responds to the movement of the main hull up or down.
The boat will be set up to allow downforce for the first test sail(s).

 

MPX Test Model / AC / RC

This is mainly for RC builders who are designing or considering what kind of foil system to use for a scaled down AC 72.
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One thing that is real important for those designing their own foil system, I think, is that both AC 72's have astounding altitude control that allows them to fly upwind very close to the surface and downwind a meter or more high. Even if they used wands the wand would have to be adjusted to allow that and the result would not be significantly better than the results we are seeing now. This is a really, really big deal for catamaran foilers and all started due to the "invention" of the three foil(single main foil) configuration and combined curved foil +L system by TNZ. These systems are being refined every single day and are a most significant contribution to catamaran foiling*.

Before this, cats simply weren't faster on foils than they were on hulls.

For RC versions that will use wand altitude control: it will be very difficult to recreate this kind of altitude control without having wands that are adjustable under sail. A three foil system(single main foil) on a cat using manual altitude control aided by the surface piercing curved daggerboard will be difficult to control if it is the sole source of control because it will be hard to see well enough from shore. The idea that John X, on his 86" AC72, is trying is a wand controlled single main foil that is probably a good compromise. His windward foil is retractable.

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On my MPX Test Model, I'm using an ama foil a bit similar to the original TNZ mainfoil but different in one major respect: my foil is NOT designed to work in concert with manual altitude control -it is designed to eliminate the requirement for manual altitude control under sail for the ama. In operation, it is much closer to a traditional surface piercing foil than to the TNZ foil. However, it may have to be adjusted on the beach for conditions(especially at the upper speed range) but the adjustment should hold for a much wider range of speeds than the TNZ type mainfoil. Also, the ride angle of my ama foil is controlled by the main foil and rudderfoil acting together to control pitch.
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Pete Melvin comments on the development of the unique TNZ single main foil:
* "“At Team New Zealand, we developed a new type of foil that allows you to keep your height above the water more or less steady. No one had been able to do that before, at least not on a course-racing boat that was not going downwind. We developed that mostly on our SL33 test boats -- they came with the stock constant curvature “C” foils and with those kinds of foils, you can generate 50% boat weight lift before they get unstable. But we noticed that when we could get one boat up fully foiling for a few seconds it would really accelerate away from the other boat – and that got the wheels turning. How, with such a huge potential benefit, can we achieve stable flight downwind? So our design team came up with the “up-tip” type of boards. More here: http://www.cupinfo.com/en/americas-cup-pete-melvin-foils-multihulls-13146.php Be sure to read part two that explains more about the TNZ "V" ,though it doesn't mention the effect of leeway on the inboard portion of the "V" that is better understood now.
Ilustrations below from ,Part 2 of the Cupinfo interview:

 

For those interested in following activity with rc multihulls:

---Follow John Xman and his 86" 2.2m rc model of an AC 72 here: AC 86- http://www.rcgroups.com/sailboats-59/

---Follow "Hydroptere" ,"Kampai26" and some of the other German guys here: http://www.rc-network.de/forum/forumdisplay.php/166-Mini-40

 

Hi doug, if he is also using a foil on the stern of the ama's as well as a main rudder foil this is also similar to my layout, I hope this means that the system that I have going through my head has more potential than I thought !!!!:idea:

 

Oooh, ok thanks Doug, that makes more sense, thanks for your reply, everything you have written makes more sense to me now and really shines the light on just how amazing and complex your design is

Thanks
Curtis

 

MPX Test Foiler

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Hey, Curtis-it's actually kinda simple in a complex way-lots going on automatically. Biggest potential problem area may be the lee ama foil at speeds over 9-10 knots-we'll see!
PS that MOD 70 thing was an April fools joke-not by me-ON me(!)... Still ,I may have the last laugh-with you!

 

Hi Doug, that will be interesting,

I was literally just in the process of saying to my Dad, hey look, I'm not the only one thinking this way and then I read the April fools thing and was like

oh well

Hey hows the boat going? I was on school camp last week so I haven't been reading the forums.

Today I finished the second float hull its now drying and I finished another 2 cross beams. I just have to do one more and close up the end that was left open when molding them and I'll be all set. I plugged the bow and stern of the main hull as well so depending on what I'm up to I might try a float test tomorrow or try our foil making method!!

Thanks
Regards

Curtis

 

Last laugh

Quote:


UPDATE #2- Just heard from Fred who contacted the editor of the publication that posted what I quoted above-and yes ,it was an April Fools joke! Well, I'll have the last laugh when the test model proves that the configuration works!


Hey Doug, I reckon we will BOTH have the last laugh!!!!!!!, :idea: