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

Fire Arrow and D4Z: What they have in common---

This is sort of a summary post of the basics of the foils being used on the D4Z and Fire Arrow Test Models-and their interrelationship:


Note: resumption of Fire Arrow testing and the first D4Z tests have been delayed. We'll get started as soon as possible.

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Fire Arrow

The foil configuration on the FA is very unique -never having been used on another trimaran ever, as far as I know. The configuration consists of four foils-two UptiP foils, one on each ama, one wand controlled main foil on the daggerboard and one rudder T-foil. Only three of the foils are used at any one time with the windward ama foil clear of the water when the boat is foiling.
One major element in this one of a kind configuration is the wand controlled main foil on the daggerboard ,which allows the main hull to fly in very light air.
After the main hull fly's a unique characteristic of the main foil is that it unloads the faster the boat goes, reducing drag appreciably with the lee ama foil taking most of the load. The reserve power of the main foil is then used, with the rudder T-foil, primarily for pitch and heave control* giving much greater control and pitch authority than on a tri without the variable lift main foil.
* maintaining a constant altitude of the main hull and the preset angle of heel of the whole boat.
In addition, the main foil is capable of generating substantial downforce in response to gusts, which increases total RM(righting moment). This response can be controlled and limited, if desired.
The UptiP ama foils ,designed specifically for this boat , do not require rake adjustment when foiling which makes them ideal for a trimaran. Because of the nature of the uptip foil, the ama flies at more or less a constant altitude 100% automatically. And because of the fact that the main foil and rudder T-foil work together to control pitch of the whole boat, the ride angle of the ama uptip foil is also stabilized in pitch. The concept of the iFlap was introduced on the ama foils as well as a 3 degree twist to the uptip portion of the foil for testing last year and worked very well. The iFlap is ,essentially, a fixed flap attached to the uptip portion of the foil in such a way that as the boat speeds up the flap will emerge from the water reducing drag. This allows the foil to have high lift at low speed and reduced lift at higher speed. In fact, it works in practice similarly to a wand controlled foil except with no moving parts.
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D4Z

Because I need help to sail and video the Fire Arrow, testing has been limited which allowed me to use some time to modify a 20 year old RC cat model to test various concepts for use on an AC 4.8RC model. The boat utilizes a "Trapeze Power Ballast System" which allows weight to be moved fore and aft and side to side very quickly. This system has been used on several different RC boats in the 90's and is well proven.
The most experimental aspect of the initial testing of the foiling version of the D4Z are the "batfoils"-surface piercing T- foils. The batfoil is curved and twisted from zero to plus 3 degrees and has an iFlap on each end which works like the single iflap on the ama foil. It provides high lift at low speed and reduced lift(and drag) at high speed ,again, similarly to the way a wand controlled foil works but no moving parts. Further, the batfoils are canted outboard at the bottom 10 degrees which allows the windward mainfoil to clear the water at a small angle of heel.
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What the D4Z and Fire Arrow Have in Common

Basically, they have the surface piercing T-foil in common because of work I did last year in trying to find a solution to getting rid of the wand controlled main foil-but only with something that would work equally as well ,but simpler. Thats a tough problem because a central advantage of the wand controlled foil is the fact that when the boat heels too far, the wand causes the foil to develop downforce ,increasing RM(righting moment) instantly in response to a gust. I did a lot of work and may have come up with a solution using an upside-down asymmetric center section that might be able to generate downforce automatically as the boat speeds up and pitches down.
It dawned on me while working on this fairly complex theory that right in front of me was a potential lifting foil for the D4Z(minus the downforce section) that would be as simple as you can get-not requiring any servos to move or retract the windward foil(as required by UptiP foils used on an RC cat).
And in playing with a fullsize drawing of these proposed surface piercing T-foils on the cat, I found that if the foils were canted outboard at the bottom 10 degrees, then it would take only 4 degrees of heel for the windward foil to come clear of the water. This was major because it allowed a huge reduction in drag by a small increase in heel!
Because of the way these foils looked before they were assembled they have been nicknamed "batfoils"(by a guy on rc groups). And before I go any further these foils were inspired, to a degree, by work Mal Smith did on a surface piercing T-foil for a Laser which I always thought was really cool.
In order to make these foils work well from the slowest speed to the fastest, along the lines of the way a wand controlled foil works, I drew again from the work on the Fire Arrow UptiP ama foils where I had devised an iFlap to create lots of lift at slow speed then have the flap ,or a portion of the flap clear the surface at speed,reducing drag.
On the batfoils, I put an iFlap on each tip-larger in area than what will probably be required-so that they can be trimmed down in testing. In fact ,the probability is that the inboard iFlap may be completely removed from the batfoils in the course of testing. Each batfoil is set at a 3 degree angle of incidence and twisted 3 degrees from the center to the tip.
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So a search for a simpler replacement for the wand controlled main foil on the Fire Arrow led to the development of surface piercing T-foils that, while very experimental, may be a great solution for the D4Z in terms of making simple foils available for the AC 4.8 class. We'll find out before too long, I hope.

 

Fire Arrow: Early Predictions

What I expect out of this test model:

Fire Arrow

UPDATED( edited): 6/12/15 --. This post will be moved and/or updated as required. The idea is to allow anyone really interested to find all the pertinent info on the boat in one place.
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11/9/14--I'm going to describe what I know now after the first series of tests culminating in full foiling on July 24, 2014. These questions/expectations were first put forward by Magnus Clarke and though the boat hasn't sailed in heavy air yet there are some things that are known now. The original of this
post is on page 88. When Dan and I have gotten more video including in relatively heavy air I will amend my responses today as required.


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These are some "questions" posed by Magnus on another forum(with a couple I have added). I think they represent a good idea in that it will allow me to summarize my expectations for this test model foiling trimaran before I sail it. And after I've sailed it.

1) Will boat tack thru 90 degrees or so upwind? on foils?
--I expect it will but I also expect that the boat has the potential to tack on foils as well as to gybe on foils. My previous RC foiler,the F3 design did it in relatively light air according to a report from a friend of another owner.In the first light air video the boat tacked fine,but in the video where she was overpowered, the rudder response was too sensitive and caused "pitch-ups". I corrected that in the foiling video but I overreacted and reduced sensitivity too much which caused tacking problems in the relatively light wind(5mph) with waves larger than would be expected. I think that is corrected now. She definitely would not tack on foils in that breeze especially with the main set so poorly-but I think she could have gybed on the foils but I ran out of time. The boat will definitely foil upwind and was held back in the foiling video by the poor set-up of the main. The boat wanted to fly upwind and she actually did for a couple of seconds as can be seen in the long video at between 1:58 and 2min in: https://www.youtube.com/watch?v=4YBOEolFqiE
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2) Will it foil in a stable fashion downwind above a certain True Wind Speed?
--Yes-above 5-6 knots TWS. The boat should begin to foil at a hull speed of 4.75 mph(4.13 knots). The foil loading and power are better than the F3 that met or exceeded these numbers.
The boat foiled in a 5 mph(4.35 knots) breeze measured with a Davis windmeter. She was very stable in pitch and tended to roll a little in quartering waves.
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3) Much of the the time downwind it should fly on "X" number of foils. And this is the behavior I expect to see.
-- It will fly with three foils immersed, one mostly unloaded, one of them carrying about 80% of the load ,the other 20% of the load. After the boat achieves full flight the main wand controlled foil will be near zero lift(except in it's roll of working with the rudder foil in pitch control) with the majority of the load carried by the ama foil and 20% of the load carried by the rudder foil. I expect that the boat will fly at a 10 degree angle of heel with the ama clear of the water most of the time. The boat should be able to foil upwind.
The boat flew with the main foil, lee ama foil and rudder foil immersed. The setup when foiling was 75% of the load on the main foil and 25% on the rudder foil. She foiled at a 10 degree angle or less. There are a couple of instances when the boat was sailing upwind where the main hull and lee ama started to lift but the wind was so light and the main set so poorly that she didn't foil upwind(Except as stated in #1 above). However, there is no doubt whatsoever that she will foil upwind as I get her (and me) dialed in.
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4) Should do "X" when it hits a puff?
--Speed up with little change in pitch and roll attitude.I expect the same after seeing her foil.
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5) Should do "Y" when it speeds up a lot?
--Generally, the same as #4.Same.
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6) When it gets upside down ,it will.....?
--Piss me off... Seriously, I expect the boat to be very stable in pitch and roll so will sail without masthead buoyancy for the first couple of times.She pitchpoled in the "overpowered" video but recovered. That was primarily due to the rudder when turning downwind. When she was foiling she was rock steady in pitch with a small roll in quartering waves. That roll could be cured by deeper ama foils which would be retractable. Always planned on that for the full size but not going to happen on the model(for a while at least).
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7) It will be very pitch stable because.........
-- Even when the ama foil is fully loaded the wand controlled main foil and the rudder foil work together to control pitch of the whole boat and,therefore, the ride angle of the ama foil. Even if the ama foil was to ventilate, it can't physically pitch down, and the planing ama would pick up the slack(lack of lift).The pitch stability of the boat was quite apparent in the foiling video and will show up even more clearly in upcoming video.
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8) Things I am not sure about as a designer include its behavior in these conditions:
a. bigger waves-the wand controlled main foil and rudder foil are very deep which should ensure pitch control in most conditions. Just what the conditions will be that exceed "most conditions" will be interesting to learn.
b. behavior of the ama foil in near top end conditions- will it ventilate, plane(like a DSS foil) or some heretofore unknown combination of foiling and planing(and ventilating). The ama foil will get critical in it's performance far before the mainfoil and rudder foil do-that's why they are so deep. The effective range of ama foil performance both in terms of speed and waves is a major element of the testing to be done. I want an ama foil on the full size boat that doesn't require a wand or manual adjustment throughout the entire speed range-that's a big ask. We'll see how it goes.
Even though we didn't have"near top end conditions" the ama foil performance was one of the big successes of the first foiling test: the UptiP ama foils worked perfectly maintaining a constant altitude even with different speed and loading. In one picture you can see the ama foil breach the surface with no apparent change in effectiveness. The foils were never adjusted before or during testing that day. I expect that in stronger winds I'll be able to reduce the foil angle of incidence and in the next test the effectiveness of the stb. ama foil with the iFlap will be compared with the port ama foil with just about 3 degrees of washin( positive twist-the opposite of washout on an airplane wing)-and equal area to the stb. foil.
c. I want to experiment with the planing ama by changing the ama foil as well as changing the bottom area(but not the volume) of the ama itself.Still to come.
d. As the designer, I want to see if the ama foil lifts the weight due to heeling moment from the slowest speed to the fastest speed-do my calculations match it's performance? I have concerns in both areas. At slowest speeds the foil may require something like the spring loaded flap to create enough lift,and at fastest speeds may require something like servo(manual) reduction in the angle of incidence. Generally, on my foilers I set the boat up with the angle of incidence of main foil at +2.5 degrees and the rudder foil at zero degrees. The ama is an asymmetric foil but I am still starting at + 3.75* degrees though that may too much. These angles are measured parallel to the nominal static waterline that starts at the bow knuckle and goes to the point where the center of the transom touches water. However, I discovered that if I tilt the boat(F3) back after setting the foils up as above, she will take off quicker. In about a 5-6 knot breeze the F3 would take off in about two boat lengths when set up this way. We'll see what this thing will do.* Actual AOI in the foiling video was about 7 degrees.Discussed in 8b above.
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Additional questions and comments:
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9) The L/B ratio of the main hull is smaller than most tris-in other words the main hull is wider. Why do you expect that it will be satisfactory?
-- The L/B ratio on this hull is close to that of a Weta full size tri and matches a 20' tri I designed and built many years ago. The hull is a planing hull and has about 20% more wetted surface(in seahugger mode) than the "ideal" rc or fullsize race tri main hull has. The model is scaled down from a full size hull I used to have which is the primary reason for the beam. But the most important factor in assessing how this hull will work is the Sail Area/Wetted Surface ratio* compared to my F3 RC trimaran foiler. And this boat has equal to more sail area per sq.in. of wetted surface than that boat does both in seahugging mode and when foiling.Since the boat took of in a 5mph breeze, it is evident that the L/B ratio of the main hull had ZERO negative effect on performance. This is a scale model of a full size "sport" foiler and I would use the same basic hull on a full size version after seeing the performance of the boat in all the videos.
* SA/WS(with Code Zero)= equal to F3 at takeoff(even with the wide planing hull), better when foiling--7/1 seahugging, 16.5/1 foiling.
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10) You've said that the projected sailing weight of this boat is 21.13 lb which exceeds your target weight of 16.688lb. How will that affect the performance of the model?
-- I don't expect it to affect the boat much because the amount of sail area per pound of weight almost equals the same measurement on the F3. The boat has enormous power to carry sail. The affect, if any, may be in very light air, but I don't expect a problem relating to weight and it's actually an excellent test for the ability of the boat to carry extra load. If this was designed from scratch as a racing rc trimaran it could have been built for 11-12 lb. but it is designed as a scale model. At any rate, the boat should be able to perform very well at this loading. I extended the stern of the main hull about 9% to improve pre-foiling take off speed. The boat took off and foiled well in a measured 5mph breeze-enough said!
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11) Full size applications in 60-100 footers?
--After re-watching the MOD 70's and Open 60 tri's under sail I'm more convinced than ever that the wand controlled main foil could be a big aid in allowing not only much better light air performance because of flying the main hull in very light air , but improving heavy air performance by improving pitch stability while also allowing the boat to be pushed harder because the wand controlled(or electronically controlled) main foil can instantaneously develop downforce as a responce to a gust giving more margin(not to mention speed) in tough conditions. In a situation like Virbac-Paprec got into a short while back the main foil might have prevented the capsize. But thats one of the reasons why there is a test model-to see if that is true-which could be a big deal.After seeing her foil I'm more convinced than ever of the potential of this foil configuration on oversquare tri's of any size.
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14) Reefing changed see post 664 for changes. Probably won't affect testing.
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15) Radio Box changed-see post 664. Will reduce size and weight of box. Makes installation of servos now and later simpler. Still allows for ama incidence control and "manual" mainfoil flap control with mounting of servos at ama and main foil servo on aft deck with wires run to box.
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16) Did you know: MPX = Max Power Experimental
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17) See post 1177 for the "bottom job" where the length of the main hull was increased by 5.25".
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18) See post 1178 for more pictures of the model with the rig on it for the first time.
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19) Technical Impressions of the Foiling Fire Arrow:
Above on this page is the updated list of mods made since the last video on July 24th, 2014. I've posted a list of the history of the development of this boat with all the related videos on this page as well, but I'm going to add another list and that is the things the worked the way they were supposed to-or better. The last video showed some major accomplishments of this design so far:
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A) The boat foiled in a 5 mph wind.
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B) the boat foiled in a 5mph wind at a weight of 21.13 lbs+ with just the main and jib. That is a major accomplishment because the main and jib have a combined sail area of 3390 sq.in. which is 160 sq.in/lb. The production RC foiler I designed 14+ years ago(F3) also foiled in a 5mph wind but she was 8lb with 1668sq.in. of sail or 208 sq.in. per lb.!
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C) This boat foiled using two completely different altitude control systems-for the first time on any size trimaran anywhere, as far as I know:
a. The main hull uses a dual wand controlled flap equipped main foil to help the boat fly in light air and to add righting moment in stronger wind,
b. The amas used a refined version of UptiP foils, pioneered by Team New Zealand in AC34, for the very first time on any trimaran anywhere as of July 24th 2014! My design for the Fire Arrow foils attempted to create a foil that would require little or no adjustment while foiling while keeping the ama flying as the main foil unloaded and the boat sped up. There are pictures showing this actually happening-"A" and "B" below illustrate the ama flying before the main hull while keeping the ama at about the same altitude even when the main hull flew-so these UptiP foils worked under two completely different load and speed cases-can't get much better than that. I think that the ama foils may have to have their AOI(angle of incidence) adjusted down during high speed sailing but we'll see down the line. No adjustments were made to the ama foils while making the last video.
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D) The foil configuration used by the Fire Arrow, as mentioned under altitude control systems above, is a one of a kind with tremendous advantages-particularly for an over square platform: Thanks to the wand controlled main foil the boat will fly the main hull in very light air which would be impossible if one waited for the sail force from the rig to allow the main hull to fly. The significance of that is that the oversquare beam is not a hindrance to light air performance and adds tremendous righting moment in stronger wind due to the very wide platform. But, the main foil isn't finished yet: as the boat speeds up the main foil is unloaded but as soon as it is required the wand controlled foil will add righting moment to the boat equivalent to half the boats weight or more! It does this because as the apparent wind increases and the boat heels a little more the leeside wand reacts by raising the main foil flap and that causes immediate downforce(righting moment).
a. when the mainfoil is unloaded or creating downforce it "works with" the rudder foil in pitch control giving this platform tremendous resistance to pitch excursions compared to almost any other boat.
b. the main and rudder foil together control the ride angle of the ama foil so that it is incapable of any sort of pitch reaction on its own-either up or down.
This was one of the things so evident in the video and one of the great successes of July 24th.
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E) This doesn't mean the boat was perfect in the last video-I, as well as a few others, have pointed out areas that need work. We haven't sailed in strong wind with the boat working this well and there is plenty of refining to do(see the "mods" list above on this page). But I wanted to take a few minutes and point out the things that were successfully accomplished on July 24th, 2014. Dan and I will follow up the excellent results on the 24th in 2015 in heavier air with some exciting video.

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All videos can be seen on my youtube channel here:
https://www.youtube.com/channel/UC6S7JPG1d2uZ91lqt7ObyIw
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Pictures "A" and "B" as discussed in 19c above:

 

Gibt es noch jemanden der das alles liest ?
Was zum Teufel is' D4Z ?
Mensch Doug !
Die Revolution frisst ihre eigenen Kinder.
Klein und klein bleibt klein.
Cervantes hat seinen Titelhelden auf ähnliche Reise geschickt, Mühlen waren Drachen.

pogo

 

Fire Arrow and D4Z

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Too bad you don't read it. Whats the point of your post??!! If you don't like the thread and if you don't read it and/or don't understand it ,whats the point?? Why waste your time commenting on something you have no interest in -whats the point??

 

Foiling in light winds

Had quite a successful Saturday with the Mini40, foiling with the top suit up

https://www.youtube.com/watch?t=14&v=_8lmu54sZ1o

Not so good with the One Metre tri - had some long, deep, thin foils on which did not work. Back to my shorter thick ones . . .

 

RC Foilers

Great stuff, Ian! The sails on these boats look particularly good.... Thanks for posting.
https://www.youtube.com/watch?t=14&v=_8lmu54sZ1o

 

More progress

More action from last weekend is here - light winds and strong winds.

On the Sunday I bent the rudder shafts on both boats - hence the erratic steering in the videos - and cracked a foil on the Mini40. The videos themselves are also erratic as I had the video camera taped to the transmitter as my usual cameraman (14 year old son) was not available.

The One Metre was using modified foils - cut down from the previous weekend's attempts - and was performing significantly better, in both the light and the strong winds. On the Sunday the One Metre had its D rig up, which was the right rig for the strong gusts. Nice capsize at the end of the video, which is also caught with the onboard camera.

Mini 40 action here
http://youtu.be/Tx5mU76yYII

One Metre action here
http://youtu.be/MyJ5hS-eeWc


Anyway, quite a bit of repair work to do before the next sail!

 

RC Foiling Tri's

Thanks Ian!
Mini 40:
https://www.youtube.com/watch?v=Tx5mU76yYII&feature=youtu.be


One Meter:
https://www.youtube.com/watch?v=MyJ5hS-eeWc&feature=youtu.be

 

Testing --Heads Up!

May be able to start testing later this week or next week (probably) for sure. There are still problems that could prevent that but I'm reasonably hopeful.
Probably some time in July our whole waterfront here is going to change. The Association is putting in a completely new seawall including steps from the grass to the water which will make it feasible to launch the boats right in front depending on conditions.

 

Fire Arrow and D4Z Testing

My test partner Dans father has fallen a second time in the last couple of months and may have to have surgery next week. From my experience taking care of my parents for 20 years I know what he's going through. Needless to say there won't be any Fire Arrow testing for a week or two at a minimum.
I may take the cat out and try to get video with a tripod-IF my fever lets up...
Thats the way it goes.........

 

Fire Arrow and D4Z Foil Testing

I want to thank Jim in Australia for his offer of help in getting testing back on track. Too bad he lives so far away! We'll get going sooner or later.......

First foiling almost a year ago-and in a 5mph wind:

https://www.youtube.com/watch?v=7Mok3d4KiMI

 

Photo test---Fire Arrow first time full foiling July 24th, 2014 using one wand controlled main foil and a single UptiP foil, 5mph breeze:


Waiting:

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Picture test-First full foiling July 24th, 2014, 5 mph breeze:

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Fire Arrow first full foiling July 24th, 2014, port tack, 5mph breeze:

 

Fire Arrow Foiler / MPX Foil System Testing and Development

picture test:


UptiP ama foil: