MPX Fire Arrow RC Trimaran Scale Test Model

MPX Downforce

MPX Downforce

Wolfgang, here is an illustration of the downforce and its component to weather and a similar sketch of the component to weather of a Moth foil when heeled to weather. Didn't realize they would be so large-at least they're clear(!) :
MPX Downforce.jpgVeal Heel dl 2012 N.jpg
 
MPX Test Model-First sail!

MPX Test Model-First sail!

Sailed in very light wind. Boat did about windspeed even with the mainfoil flap down 30 degrees(as it should be prior to takeoff, but not conducive to light air speed). Of all the crazy things I forgot the jib and Code Zero-so we had to sail with main only-even though I had a checklist. My friend Coach Dan Burke took the video. Very happy with the days results....
 
You Tube video

You Tube video

Please accept my apology for the audio on the video-I asked them to fix the shakiness and they did but ruined the audio. I asked them to put it back like it was originally and they added the shakiness back in but the ruined audio stayed. Now I've got the worst of both-though the shakiness is not that bad-the audio unintelligible for the most part.
 
Youtube videos-music added

Youtube videos-music added

I've added music , chosen from selections provided by Youtube to cover the botched audio. Should be available on the videos shortly.
 
Hey Doug, congratulations!! I know the feeling to go out after a long building time. She sails smoothly and tacks very easy. Now you need more wind and a little less twist in the main I guess.

Keep us updated! Chris
 
Fire Arrow(MPX Test Model)

Fire Arrow(MPX Test Model)

Thanks , Chris! The main is completely adjustable so the twist can be optimized before the boat is launched. Next time I'll remember the jib(!). Tuesday next week the earliest.......
 
MPX Testing and Development----First Flight!

MPX Testing and Development----First Flight!

Against my better judgement I sailed yesterday in 9-11mph(8-10 knots). Before yesterday I exercised great patience in gradually testing one step at a time. But the sailor in me trumped the designer and I sailed. Man, was it fun! The dynamic pitch ups and pitchpole were skipper related-poor handling. Almost immediately something happened to the sheeting system but I continued to sail-hope I didn't ruin the Guyatt winch. It was a handful with partial control of the sails! I know now that the foils work and that a 21lb(9.6kg) boat will fly! Need to improve the video, get a #2 rig, and sail in flat water to adjust the foils, but all in all it was a great day.
Youtube is adding music that I picked out -probably won't be ready for a couple of hours but the video will work with the original audio....MPX Foiling-- Foil Assist-Flying Main hull Over Powered 009.jpg

 
Video

Video

Youtube has finally finished adding the music and removing as much of the shakiness as they could. It should be easier to watch....
 
MPX Testing -First Flight

MPX Testing -First Flight

Some interesting technical facts: based on the boat sailing in 9-11mph wind
and flying the main hull. Boat is an oversquare platform and the full size boat would require about 17mph of wind to fly the main hull w/o the main foil-which will allow the main hull to fly in as little as 5mph of boat speed(6-7 mph wind speed ,estimated). One of the main functions of this design is to use the mainfoil to fly the main hull BEFORE it would on the basis of just wind pressure.
MPX Test Model:
1) Heeling moment at 11mph wind about 45.2 ft.lb.( .48lb/sq.ft pressure on 23.54 sq.ft @ 4' )
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2) Heeling moment at 9mph wind about 29.2ft.lb. (.31lb/sq.ft. pressure on 23.54 sq.ft @ 4' )
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3) Righting arm with both the ama and the ama foil supporting some of the weight= 3.04'.
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4) MAX RM of boat with ama and the ama foil supporting the weight required to fly the main hull: 3.04 X 21.13= 64.24 ft.lb
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5) Ama buoyancy 7lb
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Conclusions:
A) At 11mph wind and boat weight of 21.13(discounting rudder foil loading) :
--1-So vertical lift required of ama + foil for this HM= 45.2ft.lb divided by 3.04=14.86lb (so even with ama submerged ama foil would have to generate 7.86lb of vertical lift).
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--2) Vertical lift required of main foil at this wind speed=[21.13-14.86]= 6.27lb
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B) At 9mph wind speed and boat weight of 21.13(discounting rudder foil loading) :
--1-So vertical lift required of ama + foil for this HM= 29.2 divided by 3.04= 9.6lb (with submerged ama ,foil would have to generate 2.6lb of vertical lift)
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--2) Vertical lift required of main foil at this wind speed =[21.13-9.6]= 11.53lb.

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This, coupled with the video is conclusive proof, beyond a shadow of a doubt, that the foils worked in arduous conditions and that they allowed the boat to fly the main hull in conditions where it would not have been able to do so otherwise due to its oversquare beam. Which was and is the central rationale for the MPX foil system.
 
MPX Testing and Development------Problems and Solutions

MPX Testing and Development------Problems and Solutions

Here are the problems encountered in the last test sail-part of which is shown in the video
1) Dynamic Pitch-up's: there were two dynamic pitch ups where the bow jumped up during a turn. Both those and the almost pitchpole were caused by abrupt rudder movement. In the one captured on the screen shot below, the hard rudder movement threw the boat completely clear of the water except for elements of three foils. Amazing power to do that on a 21lb scale boat. Solution is probably to enable dual rate and or exponential on the transmitter, though with practice a smooth turn could probably be learned.
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2) Vang and downhaul--the gooseneck slides on a vertical rod. I tied the downhaul to the gooseneck so as the vang was tightened the gooseneck tightened the downhaul. Unfortunately, the power of the vang stretched/loosened the line dissipating the vang power-so when it was tightened to de-twist the sail it may have done that for 10 minutes but then nothing. Solution: decouple the downhaul from the gooseneck and fix the gooseneck so that it can't move down(or up for that matter). Maybe add a cunningham grommet if there is not room around the gooseneck for the downhaul to work. Increase the purchase of the downhaul to 8/1.
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3) Peak Halyard and GCD-Gaff Control Device is the thing sticking up above the gaff to which the peak halyard is attached-line stretched. Solution: convert to spectra and /or increase purchase. I may change the position of the bowsie in order to make it easier to adjust when the Wing Tip is in place.
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4) Sheeting system-line from the jib side of the drum jumped off because, under a lot of load, the sheet induces slack at the drum. This actually makes me happy-I was afraid I might have stripped the $380 winch! Solution: add a block with a spring to that side of the drum so slack never happens. Note to self: never subject the winch to loads outside its design range-reef, switch rigs or don't sail!
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5) Rig slack. This happened because I didn't tighten the shrouds enough for those conditions which allowed the rig to go fore and aft a lot which allowed the top of the main to have undue influence on the pitch stability of the boat as well as screwing up the set of the jib. Will discuss the matter with the crew to see to it that the shrouds are always tightened.
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6) Being overpowered:
a. I dodged a bullet this time by not ruining the sail winch-it is NOT set up for the load found with a 9-11mph breeze+boat speed+ waves. Will go with the SA limits I know and use the windmeter to make sure I've got it right.
b. Will design and build a new #2 rig instead of reefing the original main*. The reefing system I used on previous boats won't work with the rotating wing mast.
I was mighty impressed with the way the boat handled the fact that it was overpowered and sailing in big waves(for the model) so I want a rig that will hopefully allow sailing in almost any condition. Removing the jib in those conditions wouldn't help-too much wind for the main only.
* This will be expensive and take some time. In the meantime I have an old rig for a much smaller boat that I may use. Will at least have entertainment value when the mast snaps like a twig......

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Next test sail will be in wind between 5 and 7 mph*. The designer(that would be me) says the foils should work in those conditions and the boat crew(that would also be me) has been warned to not repeat the joyriding in unscripted conditions!
*I tend to use mph and not knots because the wind pressure table I have is in mph and the foil lift formula uses mph(ft/per second). If you want knots divide mph by 1.15.
Stay Tuned........
MPX jumping clear 2.jpg
 

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Fantastic Doug! You really did it! And she flies very early and stable!

Now you need to optimize it over and over again. If you can get rid of the twist in the main she will maybe fly even earlier. Do you think the ama-foils should be longer (reach deeper)?

Congratulations! Chris
 
Fire Arrow on Foils!!

Fire Arrow on Foils!!

Thanks, Chris! I don't think there is any point to increasing the ama length. The refinements now are to add the reefing system to the rig which involves cutting the mast and creating a removable insert, getting a handle on reducing main twist, deciding how much to reduce the ama foil i-flap area, experimenting with adding a (removable) wider planing surface to the ama and more.
The ama foil is quite experimental and is inspired by the TNZ UptiP foil but with some major differences. Each ama foil includes a molded in flap whose area will be reduced after more testing.(see sketch) The way it works is that the molded in, fixed flap acts to lift the ama early-even before the main hull and as it lifts the uptip portion(with the i-flap) breaches the surface reducing the high lift drag of the flap. In other words, the UptiP foil with the i-flap acts like a wand controlled t-foil except with no moving parts. In his first video the "solid state" ama foil had excellent, intrinsic, altitude control. Testing will improve this with lower wetted surface.
MPX---iFlap rough sketch.jpg
 
Tacking

Tacking

Had a problem tacking, as shown in the short video. The cause, primarily, was that I set up dual rate and expo in two different combinations but with no way to turn them off! The video before this showed the boat with several "pitch-ups" caused by abrupt rudder movement and I used the dual rate/ expo to de-sensitize the rudder. Unfortunately, I went too far--simple fix, though.....
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Chris, on the full size boat the ama foils will be retractable and could be lengthened a foot or so. But if I did that on the model the windward ama would probably drag too much-I'm not ruling it out just not something I'm going to fool with now.
For the next test sail, I've modified the port ama foil to remove the "i-flap" but keep the same planform area. If that works it will reduce drag throughout the speed range and I'll remove the flap from the starboard foil as well. If it doesn't work with the same early takeoff I'll add the flap back to the port foil. It will be easy to see which foil works best because only one is being used at a time.....
 
New type of hydrofoil-IF it works!

New type of hydrofoil-IF it works!

I can't test sail the Fire Arrow alone and my "crew" is tied up for a while longer. So I have been working on a couple of other projects in the mean time. One of them is a surface piercing main foil with an inverted asymmetrical foil section in the center. The idea is to simplify the foil system(particularly on the full size version of the boat) by eliminating the wand system that controls main hull altitude by moving a flap attached to the main foil.
The main foil, with dual wand controlled flap, is unquestionably the best for performance. But since this is a scale model of a "sport" boat and not a scale model of a race boat, I've been trying to see if I could come up with a surface piercing main foil that could somehow be designed to produce downforce before the main foil flys clear of the water due to heeling force- to further simplify the foil system.
Right after takeoff, whether the main foil is a surface piercing foil or fully submerged wand controlled foil, it begins to unload with more and more of the load taken by the ama foil. That's all automatic. And the characteristic of the boat as it speeds up is to pitch down. My use of the asymmetric center section is to take advantage of the fact that an upside down asymmetrical foil will generate vertical lift(an airplane with an asy wing can fly upside down) with the right angle of attack and that while upside down it will generate downforce with a low positive angle of attack or zero positive AOA, while the inboard sections* of the symmetrical foil are at zero degrees angle of attack producing no vertical lift-all this when the boat is at max pitch down.
Whats hard in studying this is to remember that the heeling force is increasing as the boat speeds up and pitches down. And that the heeling force unloads the main foil.
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At max pitch down there is a symmetrical foil and asymmetrical foil cruising along right next to each other ,separated by fences. The symmetrical foil is at zero degrees AOA and so is the upsidedown asymmetrical foil. Because an asymmetrical foil can generate vertical lift at zero degrees AOA, it can generate downforce when inverted at the same angle of attack!
So I guess I think it's ,at least, worth a test.....
*which are the only portions of the symmetrical foils that are immersed at that point.The section of the main foil outboard of the fences is symmetrical transitioning to asymmetrical(right side up) at the tips.
Automatic main foil-small- 10-11-14  -.JPG
 

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Fire Arrow Foil System on 70' MOD 70 Maserati!

Fire Arrow Foil System on 70' MOD 70 Maserati!

Watch this video of Maserati-she is flying on an uptip foil on her stb ama and on a foil on her daggerboard along with a couple of rudder t-foils. Her foil system is nearly identical to the Fire Arrow system developed over the course of 4 years and successfully tested in 2014 in light air. Maserati proves that the system works on a large tri in the ocean:


Watch the video above very carefully and you can see the foil on the daggerboard-this is so cool I can hardly stand it!

More: http://maserati.soldini.it/

What Team Maserati says about it:
First* trimaran in the world to fly with effortless stability on the horizontal loading-bearing surface of her centerboard, Maserati Multi70 brilliantly puts into practice Guillaume Vernier and his Team’s idea of flying on three resting points using a load-bearing centerboard, L-foil and a rudder instead of the two rudders and single foil adopted on America’s Cup cats.
Giovanni Soldini and his Team are engaged in a new challenge as they endeavour to turn Maserati Multi70 into the first ocean-going flying trimaran. An ambitious project that spans not just Guillaume Vernier’s excellent work (he worked on the modifications to her appendages) but also over 4.000 nautical miles of sailing clocked up by the Team this summer.
The straight central daggerboard plays a revolutionary role in this new flying trim as the horizontal load bearing surface at its end generates lift, raising the boat out of the water. “When Maserati Multi70 rises up on her lateral foil and rudder, the daggerboard wing acts as a third resting point – the central and largest one”.
Tests in wind of 40 knots have demonstrated that Maserati Multi70 is now much more stabilized and able to fly in conditions unthinkable before. Safely tackling also big seas.

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* Wrong-the Fire Arrow was the first trimaran in the world to fly on a daggerboard foil in combo with uptip foils on each ama.
 
Fire Arrow Foiling System-The Foiling Week Awards

Fire Arrow Foiling System-The Foiling Week Awards

Please vote here for the best foiling project-please vote for the Fire Arrow. We probably can't win but nothing says we can't try-your help will be most appreciated!

one.foilingweek.com/awards2016.php


Fire Arrow flying in a 5 mph wind 7/24/14:

71lmw3.jpg





Maserati using the basic Fire Arrow System 7/18/16:

2ntg3tg.jpg
 
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