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

MPX Testing and Development

I've decided to adjust the older unmodified ama foil(stb) to a higher angle of incidence because the one thing in all the video the ama never lifted its bottom above water*. It did before the video was started but only for 30 seconds or so.
Since the wind was coming up all the time one explanation could be that the thing was just overpowered because we know 100% for certain that the main foil and ama foils were developing lift. The ama foil is real easy to adjust at the beach-the mainfoil has to be set up in the workshop to be checked-so it has to be right before we get to the sailing site.
Because there will be so much less drag with all the fixes especially to the rig. mainfoil and wands(in that order) the ama should clearly lift next go round as the main hull flys(or sooner).
*Increasing the AOI on the ama foils is counter intuitive-we'll have to see if it works....

https://www.youtube.com/watch?v=LmXCdAlo4mk&feature=youtu.be

 

+1 for keeping up with the vids. We all want to see it in action.

 

Go pro, yep the batteries don't last too long, perhaps 18 months then they cannot hold a charge.

Go to a store and try a fresh battery in the store with your cam to see if it can be revived.

 

MPX Testing and Development

Thanks, Dennis. Good ,bad or indifferent the story, the videos and the analysis will be here....

 

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Battery was fine. Went thru a whole series of experiments with "Brendan" by e-mail before they washed their hands of it. I will say that Brendan was first class in trying to help me get it going right up to the "out of warranty, no repair" comments. A sailmaker friend who is also very into electronics has it now with carte blanche to try anything to bring it back. I'm convinced-right or wrong- that go pro knew exactly what the problem was and that it certainly wasn't caused by sitting in the packaging for two years. Bottom line is that I should have checked it when it came in-I'd bet it was non-functional then,but those were harrowing times around here in early 2012.....

 

A suggestion on foil angles etc.

We had a lot of trouble dialing (Calibrating) in any kind of set point on the foils as a sort of baseline to be able to measure against especially getting it same same from side to side. It's a universal problem on boats with foils where a single degree can make all the difference in the world.

So at one point we jigged up the whole boat on horses and leveled it all perfectly. This was easier because Steve Killing was smart enough to design the boat so one portion of the deck close to the foils was exactly parallel to the static waterline. so we leveled the boat fore and aft, and side to side.

From there we got the foils set up simply so the trailing edge was normal to that, namely straight up and down, which again we could do with a digital level. Because the foils were not exactly in the same place fore and aft in the boat we stopped trying to measure to some point on the lower end of the foil back to the transom.

Instead I simply built a calibrating jig out of hot glue and foam core. Cheap cheerful and very quick and useful. It had two "sections" of the boat from the back of the foil, and two feet further aft. Essentially it would cup onto the bottom of the hull in the same place every time. Then it had a flat plane, vertically running fore and aft that connected the two sections. It also had a plane extending forward beside the foils trailing edge with some over-run. On that I had just plotted up a big "compass" or set of lines with numbers indicating +10 degrees all the way to minus 10 degrees. So at a glance we could see where the whole foil sat on any given day.

After we had the jig built, we didn't need to level the boat again, we could just put the boat on horses at any angle, drop the foil to depth, and then verify the angle it sat at. On the deck we could fine tune the gauge that indicated foil angle (Tape with sharpie numbers on it) in a matter of moments. Because all of our controls are string we have to assume that there is always the possibility of it changing, so you just check it once a week or whatever. Either way, once you have a jig to attach to the boat, it's super easy to deal with and more importantly, its very repeatable which is the most important part and it allows for very fine tuning after that.

To be clear, once we used the foils a lot, we stopped worrying too much about exactly what angle anything was at, we worried a lot more about relative angles. So we get the boat flying happy downhill, then we know we simply want to get rid or two degrees for upwind work. Or the breeze cam up five knots, the next time I head down hill I need only 1 degree of foil from where I am now, not two degrees.

FYI, the rudders are far harder to set up right. For that we used lasers and jigs. In short we had a piece of material glued up on top of the foil, to be the exact shape, in other words a foil-top jig that was perfectly fitting. We sanding the top of that flat so we could attach a laser to it, or a digital level. Then we'd level the boat, and shoot the laser to a far away target. then move it to the other rudder and do the same, they should both shoot at the same height on the far target if they are aligned left and right, which is all that matters really.

For a model boat, its small enough I would be tempted to build a jig for the entire thing that captures all the hulls and foils at once. In fact if I built a boat from scratch I would start with that jig simply to get the hulls / amas all lined up right in the first place. It would only stand to reason that I would extend the same jig for foil alignment if it's an issues, which it is.

 

MPX Testing and Development

Thanks Magnus. So far, using the straightedge on the table and leveling the boat fore and aft is fairy quick and repeatable(see post 1482). I would like a full size jig but there is no room, so I'm content with this. The rudder is set at zero relative to the static waterline ,which is relative to the top of the straight edge and also parallel to the theoretical flight waterline. I say theoretical because the actual flight waterline is relative to the boat at an angle of heel.
Man, I feel very confident in the boats potential performance with these incredible building/assembling errors corrected! We don't need the mainhull altitude I originally set up, so I'm shortening the wands 5"(instead of the 3 I mentioned earlier) but they'll be adjustable*. And the main foil will be at 2.5 degrees(instead of the 4.5 it was in the video) with the rudder staying at zero. She'll be set up so that she flies just above waves like she did several times in the video. And if more clearance is needed to prevent bottoming out, I'll just lengthen the wand a bit.
* So far ,though, I haven't figured out exactly how to make them adjustable. Give me another hour or so......
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Thanks again for looking in-I appreciate the effort!
PS- just discovered a potential source of the "movability" of the wand plate which the mainfoil is mounted to: you may be able to see, in the picture, the rubber washers on each of the two bolts that hold the plate. The little bonded in bolts I got from Dragon Plate stuck up too high so I needed something that would take up space and not require spending a lot of time undoing the nuts to adjust the foil. Those had really crushed down and appear to have allowed some movement either before the lock was installed or after by wracking-though they seem tight. Anyway, I'm tossing the rubber washers and replacing them with fiberglass washers(because I have them).

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MPX Testing and Development-----New, Shorter, Adjustable Wands

Figured out to make the wands adjustable. The new wands,at their longest, are 5" shorter than the wands in the last video. The system uses a small diameter stainless steel wire glued to the inside of the wand. The wand/paddle/wire assembly slides thru the inside of the wand mount. The wire is bent over and retained with velcro. To shorten the wand, the velcro is removed and the wand shortened up to 2 inches and retained with the velcro-shorter than that would probably not be required but it can go 2.5 inches shorter but then the wand tip is above the bottom of the hull at flap neutral. The wand is coated with cyano to make a tight fit in the wand mount.

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MPX Testing and Development------Radio Programming

Programming the "8FG Super" radio with the "Touch Sensor" is a real pain. Years ago I programmed a very complicated twin rotor side by side helicopter with all kinds of mixing and it was very straight forward. This thing changes if you breathe on it the wrong way-it's very sensitive to finger pressure and the slightest change opens up a whole new screen , then you have to go back-its constant change/back and very, very frustrating. I will never buy a radio with this kind of programming interface again.
So what I've decided to do is set Dual Rate at 75% and set Exponential at -30 on each side, with the DR switch on and off. So I'll have expo either way. I ran out of battery power just a few minutes ago trying to understand how to do this. I only have one transmitter battery so I'm thru until tomorrow morning.
Dennis,Magnus or anyone else: if you've got ideas on the values I should use for DR and Expo-let me know by 10 tomorrow morning-please.
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I inspected everything on the boat and added the lock and new washers to the wand plate then reset the angle of incidence(rake) of the main foil to +2.5 degrees from 4.5 and checked that the rudder was at zero. I then removed the mainfoil and reassembled it to see if the settings were the same-they were. So pretty much ready to go after I finish the programming-I'd rather grind carbon than use this idiotic "touch sensor" interface.

 

MPX Testing and Development----First Flight!

Here is the original "Take Off" picture next to a new picture(both screen shots from my video) posted on another forum showing the boat in mid-pitchpole(wannabe). Of course, the pitchpole is shown in the last video and some guy ,hoping to ridicule the boat, took this screen shot and added the commentary. No mention that the boat recovered from this attempted pitchpole!
It's all good stuff and part of the on-going history of the development of this concept. Actually, Team New Zealand did a pitchpole wannabe just like this-maybe not as far over-but she recovered just the same. He who laughs last laughs best....

PS- the Fire Arrow pitchpole wannabe was directly caused by abrupt rudder movement during an attempted gybe-live and learn. We now know that abrupt rudder movement on this boat can fling the hulls completely clear of the water and, coupled with an overpowered ,poorly set rig cause the lee hull to bury resulting in "Splash Down"(!)........ I looked closely at the rudder attachment today and no damage at all. It still amazes me like it did 14+ years ago with the boat I built for Dr. Sam-back then we did it for kicks and he caught the last picture below.

UPDATE-7/8/14-- There is no doubt the rudder induced the two pitchups seen below. However, the Flyer^3(cubed) did not have lifting hydrofoils-only one rudder and one daggerboard. You can see from the pictures that each has about the same pitchup attitude, but the Fire Arrow hulls are clear of the water. So my emerging theory on this is that the rudder started the pitchup but the drastic increase in angle of attack of the foils allowed the thing to jump clear of the water-something the Flyer^3 did not do.

 

MPX Testing and Development

Programming went smoothly this morning even with the aggravating "touch sensor". The settings are:
1) DR-SD switch off:
a. -40% on each side expo
2) DR-SD switch on:
a. Expo-30% each side, and
b. Dual Rate set at 75%.
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Increased the angle of incidence of each ama foil to approximately double what it has been(2 X 3.75)= 7.5 degrees. This should be way too much. It can be adjusted down at the site. I did both foils so I see the difference between the two different foils.
The boat is ready to fly but I still have to try to get a tripod together.
Also going to experiment with fitting the old microMoth rig to the boat as a "storm sail".

 

MPX Testing and Development--------Storm Sail?

Here is the size sail(5.5 sq.ft.) required to allow this thing to sail in 25mph+ wind(22+ knots). The sail was the main on a small foiler model called the microMOTH-also shown below:

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When's the next sail DL? Time to drive her hard
Noticed this on one of the return legs, when it was sheeted on and wasn't any steering change, quite evenly lifted up in a gust and dropped back down, just gotta feed the foils power!

 

MPX Testing and Development

This is a summary of the changes /fixes made since the last video:
1) AOI of mainfoil reset at +2.5 degrees,
2) AOI of each ama foil doubled from 3.75 to 7.5 degrees(should be too much),
3) Sheeting system travel reduced which should allow the main and jib to luff at the same time as opposed to the jib luffing early as shown in the video about 4:10 in. If this fix isn't good enough may need to add a separate jib winch,
4) Vang and downhaul decoupled and now separately adjustable. Downhaul now 8/1,
5) "Peak halyard"/ gaff control line changed to spectra and purchase increased to 4/1,
6) Wands shortened 5". Wand now adjustable between 7.25 and 11.75". Made adjustable,clip on wand paddle extensions to allow wand length increase of 2"-just in case,
7) Wand plate attachment system changed-eliminated flexible washers,
8) Wing Tip cut down slightly,
9) Rudder(ail/cyclic) channel on radio programmed to reduce the incidence of dynamic pitch-ups(and/or pitchpole) caused by abrupt rudder movement.
10) Shore crew properly chastised for allowing boat to be sailed with loose shrouds(resulting in a saggy forestay).
11) added clear Super Lube grease to both wand axle retainers: last time salt water got into the tubes and slowed the movement of the wand axle-had to take the boat out front and use the hose and spray nozzle to clean out the salt-was hard to get to 100% again.
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Tried to test this morning but no wind at either of two sites that met the 5 to 8 mph criteria. Next shot Thursday.

 

MPX Testing and Development----First Flight!

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Geez, DR I just looked closely at that picture and the boat is 100% clear of the water with only foils in. Was that part of the last big pitch-up? If not it is evidence that I wasn't seeing things before the video started. It's also stand alone evidence that the boat flew IF it's not coupled with a pitch up. I'll have to look again for the umpteenth time and see if I can locate where this is on the video.
Clue #1- the anchored sailboat is NOT in the background of the "Take Off" picture that we know was caused by abrupt rudder movement. You may have discovered something!
UPDATE-Found it: at 4:16 just before the big pitchup the ama pops up out of the water! Only about a second before the pitchup. But that's two hops within 2 seconds with the hulls 100% clear both times. But the first hop in the video(DR's screen shot) does NOT appear to be caused by rudder movement. The second clearly is as is the pitchpole ........ Oh how I wish I could have grabbed the damn jib sheet in that part of the video!
Food for thought after we see what the fixes have left us with. There may be some positive uses for that awesome rudder power if I can tame it-or me-for "normal" flying.
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