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

MPX Test Model

Today I re-checked the angle of incidence of the mainfoil and the rudder foil because there was a slight change in pitch of the boat at static due to the hull buoyancy addition and extention.The following is final-ready to sail:
1) Mainfoil range +2.5 degrees to + 8 degrees. 2.5 is the starting setting. Mainfoil angle of incidence is adjusted by sliding the wand plate fore and aft. The daggerboard/main foil is bolted to the wand plate so that during adjustment the relationship between the rocker arm and mainfoil flap pushrod does not change.
--
2) Rudder foil is set at zero degees AOI and angle of incidence and be adjusted with some work. Epoxy "tacks" need to be ground down and/or removed. Rudder angle for steering will be set at 38 degrees(adjustable).
--
The mainfoil is below the rudder foil when the boat is setting level, mainfoil flap range: up 25 degrees to down 30 degrees. Rudder foil is a "trailing foil" and does not need to be adjustable while sailing/foiling.

click---

 

MPX Test Model-Ama Foil Theory and Reality

You really should go to page 73, post 1090 and carefully read it and also to GC32 super cat thread, page 5, post 72 and watch the video: (http://www.boatdesign.net/forums/multihulls/gc-32-super-cat-45062-5.html )
Andrew makes a very important statement about the new foils on the GC 32. He says that a main requirement of the design was that the UptiP foils(variations on TNZ's breakthru AC 72 foils) NOT require frequent adjustment-that they should control heave stability(altitude control) without having to adjust the angle of incidence of the foils for much longer periods than was possible on the AC 72's or even on the Groupama C Cat.
Now that is one of the requirements I hope I have achieved with my ama foil design-we'll know relatively soon. But regardless of how that turns out we know now, for the first time, that it is possible based on Andrews comments.
Assuming he is correct and knowing that this type of UptiP foil can be designed to be basically "set and forget" could be a major potential advance for trimaran design allowing "C" type ama foils to be replaced by UptiP foils that are designed to produce all the lateral resistance for the boat as well as vertical lift.
This technology can be applied as I am doing on a small oversquare tri AND/OR on a "normal" tri designed to fly the main hull as long as it has rudder foils on each ama. The daggerboard and the center rudder could be eliminated on such a design.
Exciting times for trimaran design if anybody is paying attention.......
-Another little tid bit: When a tri flies the main hull it's going to go faster. But if it heels too much when it is flying it will be beaten by a boat that doesn't heel as much. Theres a thread here about the angle of heel of various trimarans when the bottom of the main hull is 1/32nd inch above the water(or so) and those angles range from 13 degrees for USA 17 to 18 degrees plus for other boats. The MPX Fire Arrow will sail at a nominal heel of 10 degrees and will be tested up to 17 degrees. A wide shallow boat will heel less when flying the hull than a skinny deep main hull. The question is: does that mean that tris designed to fly the main hull,particularly those designed to do it in light air, should be wider and shallower than most "normal" tri's?? And the importance of beam in flying the main hull cannot be overstated.

 

You are getting there, Doug. Finally a picture of the "thing" in water. The level of fairing of the T-foil surfaces visible here and here is really excellent.

Don't waste too much time on cosmetics now. Get to the core of the project. You can finish the decorations later, if you want. Wasn't the goal of the project to test the concept?

Regarding the towing tests, they would IMO be useful mostly for fine-tuning the foil angles for longitudinal stability. The actual drag values would be of little importance IMO, because you have no similar vessel for comparison of the data. No "competitor" boat against which you could evaluate the drag of this one.

Cheers

 

MPX Test Model

Thanks, Slavi. I don't expect to do any tow testing-much better to test and tune under sail. Her Majesty has been wet twice before, on 4/19/13(pictures) and 10/30/13(no pictures). This last time was to check the change in pitch with the modified hull.

Pictures. Left-float test 4/19/13, Right- float test 4/11/14 with extended hull:

 

Wouldn't a float test with mast and sails or comparable weight and all foils be more accurate?

 

MPX Test Model

=================
Jim, the boat was tested at a weight that included everything. If you look closely at the pictures you can see the test weights held on the boat with masking tape. The boat will float slightly higher with the main foil and rudder foil in place due to the buoyancy of the foils themselves, but this test was accurate enough for my purposes since the weight included the main and rudder foils, the rig, the radio gear and battery plus what you see.

Click on picture for better view:

 

That will teach me to expand the pictures or get a magnifying glass!! LOL

Or better yet do both.

 

MPX Test Model

================
As one of our Aussie brethern or sistas might say: " No worries, mate!"

 

MPX Test Model-AMA AOI

This is a result of a test setup that has the main hull at zero degrees pitch angle. The ama foil is set at +3.75 degrees which is 1.75 degrees higher than I had "***"umed approaching it from a different vantage point. So I have to ponder this for a while and decide whether to reduce it or not. Off the top of my head I'm leaning toward not reducing it and seeing what happens. It gets a bit dicey, even though the idea is not to have to adjust the angle of incidence(AOI) thru most of the speed range, I want enough angle on the foil to have it start working early but not so much that it jumps out of the water or stalls. The boat will pitch up about 2 degrees when it is just starting to foil and then level off. The idea is to hit the ama foil just right so it works throughout the speed range with no adjustment. We'll see.
======================

These are the set up shots-there are lots because I want to ponder them all which is easier to do on the forum than on my computer.


click for better view:

 

MPX Test Model-final foil settings

Results of my analysis of the ama and main foil settings:
--------
The ama foil approximates closely a 63A210 section and should probably be adjusted down to an angle of incidence of 2.5 degrees(lift coeficient of .375) as best I can determine from Abbotts. I'm going to sail first with it up high-as it is now.
If the boat pitches up 2 degrees during takeoff, the angle of attack of the foil would be 5.75 degrees(lift coeficient of .75) which is outside the drag bucket of a 63A210 foil but below stall. If it runs at 3.75 degrees(lift coeficient of .53) on the first sail ,it will be right on the edge of the drag bucket*. So no reason not to leave it as is for the first run.
(earlier I had written mistakenly 63412 for the foil section- I guess because I've used it so much. The 63A210 is similar though thinner than the 63412)
--
The main foil is set at +2.5 degrees and with a 30 degree down flap, the lift coeficient is about .85. If the boat pitches up two degrees the lift coeficient
approaches 1, which is way out of the drag bucket but below stall. When it's foiling and the flap is neutral ,the lift coeficient drops to .25 which is within the drag bucket of a 0010-34 symmetrical section which approximates the main foil section.
* the "drag bucket" is a bucket shaped drop in the curve of drag coeficients in Abbots and Doenhoff's "Theory of Wing Sections". If the foil operates "within the drag bucket" it is operating with close to the minimum drag for the lift it is producing. Both foils are outside the drag bucket momentarily at takeoff.
------
Foils in Abbott and Doenhoff "Theory of Wing Sections":
64A210-pgs 596-597
NACA 0010-34-pgs 456-457

 

MPX Test Model

The uptip "L" foils pioneered by TNZ and used on Groupama C, Hydros C, Flying Phantom and the GC32 super cat are about to make an appearance on a 19' tri. This is very, very cool-the only other tri I know of that will use "uptip" ama foils is my Test Model. The 19 does not use a foil on a center daggerboard-just the uptip foils and rudder T foils on each ama. Watch the slide show that starts when you click on the url-it's the 5th boat that comes up. The ama foil doesn't have a whole lot of "uptip"* in this rendering-more like Hydros than any of the other boats. The uptip foils eliminate the need for a daggerboard on this boat since the foils are designed to provide all the lateral resistance as well as vertical lift and are way superior to "C" foils in doing that. Rudder foils on each ama are required for pitch control. This could lead the way in a revolution(not evolution) in trimaran design. The difference with my boat is that I use a wand controlled main foil for the specific purpose of allowing the main hull to fly in light air. I've written to the company that designed the Exocet for more info-like when the boat is not moving
would both amas clear the water, be lightly immersed or what? I like the configuration in that when the main hull does fly the boat will be sailing on just two foils- thats great! I wonder if that configuration could use a fairly short retractable daggerboard with a lifting foil on it-maybe not wand controlled- and designed just to get the mainhull up in light air? That would make 5 or 4.5 foils but so what if foiling in light air, with the main hull flying a lot earlier than it would otherwise, and then sailing on only two foils.

Click on the url in post 4 of this thread: http://www.boatdesign.net/forums/multihulls/radikal-t26-trimaran-perspective-design-50191.html

* keep in mind that when this boat flies the main hull the actual "UP" of the uptip foils will be greater than when it sits level ; in other words as the boat heels it becomes more stable flying. Same with my test model.

Picture-my test model with the curved ,"uptip" ama foils:
click--

 

MPX Test Model

Probably won't get much done this week thru the weekend-Real Life intrudes again. Hope to get some calm wind to try the Code Zero and will wet sand all foils and put red stripes on every foil so I can tell where its flying relative to where(how high/trim) I predicted it would fly.

Picture of the Code Zero. Between me and the sailmaker a hollow leach was cut into this sail like it was in the jib. I have never ordered a sail with a hollow leach in 40 years of ordering sails but didn't tell Scott specifically not to do it. Thats the way it goes.
click--

 

MPX Test Model

Very close to being finished. Ama foils and main and rudder foils have been wet sanded as has the bottom of the main hull. Code Zero ready to go. Need to put red stripes on both sides of all foils so that it will be easy to compare actual flight altitude with predicted.

 

The Great Race

For anyone who builds RC boats-multies or monos and who is interested in a challenge check this thread out: http://www.rcgroups.com/forums/showthread.php?t=2155833
Race info follows and there are videos and more info on the rc groups thread:

This race has been referenced in various other threads, but I figured it needed it's own thread. I am not affiliated with the organizers, but I attended as a competitor in 2013. I plan to attend again in 2015.

Race website
http://nanaimorclaser.com/the_great_rc_ocean.html

The race is a circumnavigation of Protection Island on Canada's West Coast. It's hosted by the Nanaimo RC Laser fleet and run by a terrific guy named Bruce McQuade.

Map of area:
https://maps.google.ca/maps?q=Nanaim... Columbia&z=15

The race is held on a Saturday in April and 2014 marked the 7th annual event. If you happen to have an IOM, there is traditionally an IOM regatta held in nearby Nanaimo on the Sunday.

The Great RC Ocean Race starts and finishes right off the docks of the Dinghy Dock Pub (also a sponsor of the event) and circumnavigates the island in the direction chosen by the Race Committee. In 2013 when I attended, it was run counter-clockwise.
Dinghy Dock Pub website: http://dinghydockpub.com/

 

Come on Doug isn't about time to launch the "FIRE ARROW" and show us what it can do????

We're waiting with baited breath

Bas