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

It is surprising how forgiving trimarans are when heeled to extremes. I have found that it almost balances itself on one hull when heeled at about 60 degrees, as the sails are basically feathering and countered by the weight of the windward hull and main hull. The fact that the boats rarely pitchpole I believe is down to the fact that I use quite large T foils on deep rudders. My rudders are deeper than used by almost anyone else, as I want to keep the T foil in the water so it is working. My designs also have proportionately much more buoyancy in the bows than a scaled down rc model from a full size multihull. Anything that is scaled down has insufficient buoyancy. If you look at the modern IOM (One Metre) class you will note how full they are in the bows to prevent nose-diving. The other important factor is to have the right rig up - if it is too tall then the centre of effort for the rig is just too high and the boat doesn't stand a chance when a gust hits it. Our little boats are proportionately affected far greater by small waves than full size boats and we have to do everything we can to help them stay upright! Beware of gusts when sailing slowly - especially after a gybe or a tack!

 

Fire Arrow Foiler / D4Z Foiling Cat

Good info, Ian. I made the Fire Arrow main and rudder T foil very deep and it is a nearly exact scale model of a 19.5'(5.9m) trimaran. The loss of pitch resistance and total RM due to being scaled down is noticeable. And since the D4Z uses very experimental surface piercing T-foils, the rudder foils are deeper than the main lifting foil(pix #1). The D4Z uses movable ballast for exceptional RM but with a weight penalty(though weight is removable for light air).

click-

 

Foils

Great, somewhat technical, article on passive* foils by Dario Valenza: http://carbonicboats.blogspot.com/
*wand controlled active foils work differently in two major categories: 1)wand controlled active foils that develop all the RM for the boat, 2) wand controlled active foils where the crew ,primarily, provides the righting moment.


Illustrations by Dario Valenza:
Left, foil shapes/righting moment. Right, foil areas:
click for better view--

 

Alan Bond

Just want to remember Alan Bond in this thread since he just died. He, John Bertrand and the designers of Australia II inspired me monumentally in 1983 becoming the first country other than the USA to win the Cup. The first use of hydrofoil-like wings was the most exciting design related development in my life to that point and created an insatiable interest in foils that will last all of my life. Sail on, Mr. Bond......

 

I really like what I see here, Doug, except for one thing. It looks to me like the big forward T-foil upsets the whole system, making it like a wobbly 4 legged table. Why not get rid of it (and if necessary make the foils on the amas larger, making it more like Hydroptere)?

Another thing I'd like to discuss with you is the Gunboat G4: https://vimeo.com/124676763
vs C-Fly: https://www.youtube.com/watch?t=10&v=lEqYTrzaHsc
C-Fly seems steadier to me - no dipping the bow worrysomely. While I'm sure the G4 will fly sooner in light air, isn't there a way it could be made to keep it's bow up more reliably? What if it had a sensor wand like a moth?

Would it be possible to have a sensor wand control the rudder flap, not the one on the t-dagger? Has anyone tried this on a moth? What I'm visualizing is that the twist-grip on the tiller and the flap on the t-dagger would go away, and the sensor wand would control the rudder flap (in the direction opposite) so the rudder lift would diminish or go negative if the bow starts down, and increase when the bow rises. Experiment worth running?

 

Fire Arrow Foiler / MPX Foil System Testing and Development

"Like ,a wobbly 4 legged table"...It only has three foils in the water... I must have missed the wobbly part!?The daggerboard foil is the key to the performance of this boat, allowing it to take off in very light air, then unloading (significantly reducing drag)and working with the rudder T-foil for more pitch control authority than any current trimaran. In addition, the main and rudder T-foil, working together, control the ride angle of the UptiP ama foil and the angle of heel of the whole boat. The UptiP ama foil is another key to the potential of this boat because it has intrinsic altitude control with no moving parts which makes it ideal for a trimaran. One improvement might be to have the UptiP ama foil longer so it could be raised and lowered for rougher conditions, but the complication of that installation on the Test Model is not worth it. The ama foil and planing ama are designed to work together in rough conditions.
---
The Hydroptere concept works well for top end speed but the advantage of my system is that it will fly in very light air and once the main hull is flying most of the load is on the lee ama foil with the main and rudder T-foils controlling pitch.
---
C Fly is an experimental foiler designed specifically for rough water and seems to work well though it has a bunch of foils. The Gunboat seems to fly very well in rough water-I'm not sure how you could improve it-maybe by moving the uptip foils forward though there may be good reasons why that is impossible. When she capsized it was a "normal" roll over not a pitchpole-pitch control or lack thereof was not a cause.
--
Controlling flight on the water with a wand on the rudder foil probably wouldn't work on a conventional configuration because the main foil carries around 80% of the load and would want to go it's own way. In a conventional set-up the mainfoil flap is controlled with a wand and the trailing rudder foil automatically follows with very little input required.In fact, the trailing rudder foil,( on some boats-including the Fire Arrow) automatically switches from vertical lift to downforce with no skipper input at all. In my opinion, if you removed the wand input from the main foil and transferred it to the rudder foil the thing would be very unstable in pitch. Having a wand on the main foil and rudder foil might work but it would be increasing complication for very little return.
I don't know of any experiments with this but it would be likely to have been tried in the Moth class.
The first International 14 to fly was a canard configuration with a very small foil on the daggerboard and a much larger foil on the rudder that was manually controlled. It flew but thats about all I know...
----------------------
See post 2037 on the previous page for more on how the boat works. In the video below, the first foiling was from 23 seconds in to 34 in-perfect pitch and no roll. The second foiling run(about 1:10 in to 1:30) was in quartering waves amplified by a power boat wake and 5mph of wind(waves "bigger" than the wind), yet she flew well. She rolled with the powerboat wake but that was fine-stayed on the foils with nearly perfect pitch control. I was having radio problems with the rudder channel which caused trouble tacking.
https://www.youtube.com/watch?v=7Mok3d4KiMI

 

Astonishing the interest in Doug's erratically behaved toy boat, 314 odd thousand hits and still rapidly climbing.
Realization that Doug has made perhaps half of these communications doesn't matter because it still reveals there are a huge number of armchair sailor/dreamers out there fascinated by near fantasy-land playcraft.
Of course there are a few pissed off negativists (and maybe I'm one) making derogatory comments (to which Doug blithely and with superior arrogance ignores; he has the numbers afterall) - but it is kind of disturbing that this weird escapist stuff is so over-the-top popular??

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Amazing that you would call my experimental Test Model an "erratically behaved toy boat","weird escapist stuff". What's the matter with you?! Uninformed, offensive comments like that are just silly in light of the many designer/inventers who have used radio controlled models to test their ideas. Guys like Greg Ketterman(trifoiler), Dr. Sam Bradfield(SKAT), Alain Thebault(Hydroptere), Bill Burns(CBTF), Paul Larsen(SailRocket and his new ocean going speedster),Hugh Welbourn(DSS), Yves Parlier(stepped planing hull cat),and others.

Pictures: 1) Parliers RC Test model, 2) Dr. Bradfields RC Test Model, 3) Alain Thebault Hydroptere RC Test Model, 4) Paul Larsen with his SailRocket RC Test Model, 5) Greg Kettermans RC Test Model of the trifoiler:

 

I think I saw an earlier video where the boat appeared to nearly capsize right as it came up to full flight. The flight does appear steadier in this video. I still wonder if more righting moment could be generated by making the outboard foils larger and the central one smaller; but I'm rooting for you, Doug.

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Thanks ,Steven. There was an earlier video of testing(the second time she sailed) when the wands were too long, the rudder too sensitive etc. The rudder + wands would cause the boat to pitch up. That's why she's a "test model". There is detailed analysis in this thread around June of last year.
I corrected most everything for the July 24th, 2014 video but went too far the other way with the rudder sensitivity, reducing it too much, making it hard to tack in this last video. But other than that the foils worked 100%. We could have foiled all day when that video was taken but we ran out of time.
Going to go after video in stronger wind this year. Unfortunately, I still need help with transport,launching and video. She won't be sailed w/o video being taken.
The boat is substantially over-square and has enormous righting moment but one of the advantages of the wand controlled main foil is that if the boat heels beyond her designed angle of heel(about 10 degrees) the wand causes the flap to go up resulting in instantaneous, substantial, downforce=lots more RM.

 

There is one large and overwhelming difference, Doug; sure, these guys played around with their models to get a basic indication that their new and breakthrough designs would function - and I would say, this was over a short period, like less than a year before building full size versions. In the case of Tabarly and Thiebauld, (who were the real pioneers and breakthrough thinkers) yes, they toyed with their model of the first Paul Ricard/Hydroptere but then Tabarly and later Thiebault built 6 and 7 metre versions and sailed both full sized boats intensively. They were no bathtub playthings but real sized yachts ... and I would guaran-fargo-trucking-tee, more was learned from real life-size sailing on those trifoilers in a few minutes than anything they had observed from models piddling about in a pond over a year.
Okay, sailing models must be fun, no doubt, and understandable to those too old or infirm to sail real time ... but you have overstayed your time (and your postings) with your small stuff; build a boat that can carry your own weight and then everyone will recognise and genuflect to your undoubted brilliance.

 

I only come here occasionaliy to see what negative comment are being made and to see what DL has managed to write that has any semblence of being new information and not what has been rehashed a 100 times over. I'm sure there are a huge number of others who do the same thing.

It's a case of morbid curiosity more than anything else.

 

Doug, if you can't figure out with your sensitivity of humanity and well balanced intelligence that you haven't "overstayed your time" with truck load upon truck loads of silly BS and regurgitation relating to your small water playtoys ... then maybe the first two descriptions of yourself have Chinese gybed 180 degrees and are heading in the opposite direction.
And I met Tabarly years ago and went sailing with him on Cote d'Or (the maxi monohull) and talked with the hotshot French crew about Paul Ricard and the earlier single hander version based on a Tornado main hull - and the consensus (because the French speak excellent English and politely corrected my stumbling French) was that the models were a tiny indication of reality when the larger sized boats were built. So don't BS on and hyper inflate your delusional importance of your bathtub playthings - they, and you, are just being silly.
As already mentioned, build a 6 metre version of your over-thought, over-talked, over-written about models ... and maybe many of us will change our minds about your full sized foiling expertise.

 

Gary

People just need to quit responding.

138 pages? The only reason I looked was that you replied.

Same comments I saw about 100+ pages ago.

And I agree with you.

 

And to continue: Eric Tabarly was the real pioneer in ocean going foiling yacht design - and after the model was built with a very young Alain Thebault, Tabarly built the 20 foot Tornado hull version and then after testing, had Paul Ricard built, 55 by 60 or something dimensions, a huge yacht ... and how many changes did they make to that big foiler over the years: new and different main beam, new and radically different floats, new masts, both standard and wing, different foil altering T rudder mechanisms and then a fixed setup, chopped the main hull bow off and rebuilt a finer version, then eventually dumping the complete boat retaining only the tiller from the orinal PR, so a completely new and longer version was built and renamed Cote d'Or 2.
So ask yourself, how much use and what was retained from the sail pond model to the full sized final boat?
Answer: the tiller bar!