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

Fire Arrow Foiling System Testing and Development

Here is a list of the modifications made since the First Foiling video on July 24th,2014. I've included page and post references. Updated 6/3/2016
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1) Changed the wand tension system to allow maximum force on the wand when it is down(flap generating downforce).-page 111, post 1662
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2) Painted small black section on hull immediately behind each wand(as viewed from the side) to help the white wand to show up better in the video.
-page 111, post 1661.
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3) 5 full length battens added to main,GCD removed and mast extention added, peak halyard and downhaul purchase increased. -page 109,posts 1631 and 1632.
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4) A reefing system is now incorporated in the rig with a removable mast section and velcro fasteners to hold the rolled up main.-page 109, post 1633-1634 and page 110, post 1642.
UPDATE: the lower panel of the main which was rolled to allow reefing has been completely removed for the next tests.
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5) i-Flap removed from port foil(still on stb foil) to see if I missed a step in ama foil development by not trying more area before I tried the i-Flap. The resulting foil has the same planform area as the foil with the i-Flap and a few degrees of washin towards the tip. -page 108,posts 1617 and 1618 and page 109 posts 1626 and 1630. Once I have these results I'll either add the i-Flap back to the port foil or remove it from the starboard foil. Then the process of changing the foil angle of incidence,first, and second changing foil area can start-modifying one foil at a time. The focus will be in reducing drag as much as possible within the constraint of light air takeoff which is the main focus of the Fire Arrow project.
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6) Considered adding aero drag reduction measures to the crossarms but postponed that due to a suggestion from Steve Clark,-page111, post 1653.
(While I greatly appreciate Steve's suggestion regarding aero improvements, I disagree with his assessment of the level of success achieved by the Fire Arrow in her first foiling video. My response to that: -page 116, post 1740)
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7) Added experimental endplates to the outboard ends of the partial span mainfoil flap. -page 112, posts 1667 and 1668.
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8) Added mount for a Velocitek Speed Puck to use to calibrate the i-GOTU* GPS tracker used since day one. -page 112, post 1670.
* see picture of the tracker and its installation on the boat page 113, post 1682.
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9) Moved the mast step aft as well as adding a second jib attachment point aft of the original. -see post 1772
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10) Re programmed the rudder so that exponential can be shut off. The programming used in the foiling video had two rudder programming options: either Dual Rate or Exponential but no "off". This was an overreaction on my part to the "over powered" video where excessive and fast rudder movement caused "pitch-ups" and was mostly responsible for the poor tacking evident in the video. The next time there will be Expo +Dual rate and "off".
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11) I shortened the foils 6" so that now they are at minimum wetted surface for the lateral resistance that the boat needs. And the draft will make it much easier to launch the model.
For the fullsize version max draft goes from 6.8' to 5' board down. -see post 2100,p140, 7/18/2015
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So the major experiments for the next test sail are:
1) How does the port ama foil with the i-Flap removed compared to the starboard ama foil still using the i-Flap. Want to reduce area as much as possible w/o affecting low wind takeoff.
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2) How does the aft mast step position compare with the "normal" position?
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3) How does the boat handle with the reefed rig?
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4) How does the Velocitek speed puck max speed reading compare with the iGOTu max reading?
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5) Do added battens help?
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6) Any noticeable effect from the shortened foils?
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Click for larger picture:

 

Fire Arrow Foil System Advantages(also see post 2297)--

One of the great advantages of using a properly designed UptiP foil on a foiling trimaran ama is SIMPLICITY: on the Fire Arrow the ama foil has NEVER needed to have the angle of incidence adjusted while sailing as is common on many UptiP foil applications. And if the foil is properly designed for it's application ,it's efficiency will be apparent. As shown in the pictures below the lee ama flies before the main hull, but as soon as the boat speeds up and the main hull flies the lee ama altitude remains the same. That illustrates that the lee UptiP foil is working PERFECTLY in two different load and speed cases.See pix "A" and "B" below.
The Fire Arrow uses a wand controlled main foil which controls the altitude of the main hull and the angle of heel of the whole boat. Further, and this is very important: the wand controlled main foil works with the single rudder T-foil in a bi-foiler arrangement and the two together control the ride angle of the lee ama UptiP foil. That prevents pitch excursions caused solely by the lee ama foil.
The way the mainfoil works is that as soon as the main hull flies the mainfoil begins to unload with the lee ama foil gradually taking the majority of load. That allows the mainfoil to work with the rudder T -foil to control the pitch of the boat with far more pitch authority than on a conventional tri. And, using a wand controlled(or similar) foil on the daggerboard allows the main hull to fly MUCH SOONER than it would if it had to wait for wind pressure to do it.
The mainfoil can also develop substantial downforce* increasing the righting moment in response to gusts. All this is done 100% automatically making for a simple, robust system that requires ZERO crew attention!
* with downforce, the main foil works similarly to a Moth foil with Veal Heel, generating a component of lift to windward.See illustration below.
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The vertical portion of the ama foil is at +3 degrees AOI. The vertical portion of the daggerboard is at zero degrees. So the UptiP ama foil is developing lift to windward to allow leeway coupling and develop lateral resistance for the boat particularly upwind.
In stronger conditions, when the main foil develops down force( upwind), the leeway components are greater than the vertical portion of the UptiP foil can effectively handle, there is a small extra component of lift to windward(due to downforce)-while the vertical portion of the ama foil is still working at 100%. The daggerboard is designed to be unloaded by the lee ama foil to reduce drag and facilitate leeway coupling.
However, it should be pointed out that the ama foil will still provide substantial vertical lift with little to no leeway coupling-like can occur off the wind. Lift substantially(and automatically) increases upwind because of leeway coupling.
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Testing clearly shows the progression of the boat to full foiling from the problems encountered at the beginning-the last video is 100% proof that the foil system worked perfectly-regardless of any uninformed attempt to say otherwise. But testing is not done yet even though we reached a major milestone with the boat foiling in a 5 mph wind while using two different altitude control systems simultaneously. Hopefully, starting in June we'll get a lot more video and in stronger wind. But July 24th, 2014 was a major accomplishment for the boat after a great deal of development-and we will build on that as testing and evaluation continues.
Attributes of the Fire Arrow foil configuration:
1) allows an oversquare trimaran to foil in very light air,
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2) allows full foiling upwind and downwind completely automatically without any adjustments by the crew,
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3) allows for retractable foils controlled from the cockpit,
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4) allows the lee UptiP ama foil, with an AOI of +3 degrees, to unload the daggerboard(AOI zero degrees) for reduced drag and enhanced leeway coupling.
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5) the foil system has considerably greater pitch authority than any conventional trimaran,
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6) allows automatic control of the angle of heel of the whole boat,
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7) allows automatic control of the ride angle of the lee ama UptiP foil.
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8) allows mainfoil to automatically unload as the mainhull flies ,dramatically reducing drag.
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9) allows automatic gust response with instantaneous increases in righting moment (automatically) as required.
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10) allows a "Two Stage" ama that provides back up buoyancy if needed but allows the part of the ama that would normally make incidental contact with the water, to be as small as practical.
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The short version of the final test video from 2014 showing the boat foiling in very light air(5mph max). The first day that the foil system worked 100%!
The foil system worked perfectly in this test but I still had a problem tacking in the very light air . The waves were bigger than they should have been for the amount of wind and I didn't handle the tack as well as I might have. If you notice when the boat takes off on foils on port tack I decide to tack rather than gybe. I believe that had I gybed she would have continued flying thru the gybe. I'm convinced- in the right conditions- she'll gybe on foils. She already has shown that she will foil upwind,again-in the right conditions.
https://www.youtube.com/watch?v=7Mok3d4KiMI


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The pictures below illustrate that the lee UptiP foil is working PERFECTLY in two different load and speed cases-providing automatic altitude control:

 

Fire Arrow Foiling System Testing and Development--Gust Response

This has been mentioned in previous posts but probably not stressed enough. With the square top main the boat has excellent gust response with the rig. But of even greater consequence is the gust response due to the wand controlled main foil.
When the boat is hit with a gust that isn't dissipated by the rig response the wand causes the main foil to instantly develop downforce and maintains that response as long as the gust lasts until the boat is restored to it's designed angle of heel(10 to 17 degrees, depending on wand set up).
Downforce has been discussed in detail a few pages back but for the purposes of understanding the main foil gust response here is what happens.
The wand length(adjustable) controls the angle of heel of the boat by moving the mainfoil flap up or down. When the boat reaches its designed flight angle of heel the wand causes the flap to be neutral or slightly up flap depending on the wind. Since the mainfoil is set at a positive angle of incidence* it is still producing lift at neutral flap and as the wind increases to the point that lift from the main foil is no longer needed, the flap will move to a slightly up position so that the foil is no longer producing vertical lift.This is the neutral position when the wind is strong enough for the heeling force to support the main hull. At this point if a gust hits the boat the wand will instantly move the flap up to whatever degree required to restore the boat to the designed flight angle of heel within the range of flap neutral to no-lift flap up. This range of the design flight angle of heel is just a couple of degrees and is totally dependent on the wind strength. Further, the wand makes these changes 100% automatically.
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* The main foil is a symmetrical foil set at +2.5 degrees angle of incidence relative to the static waterline which is parallel to the flight waterline after takeoff. The angle of attack of the main foil changes as the boat speeds up and pitches down slightly.

 

Sail Winch

Ian Holt: what do you use for a sail winch on your one meter foiler and on your mini40 foilers?

 

winches

All my boats have rmg winches with Deans plugs to the batteries, mainly so that I can swap them easily and quickly between boats

 

Sail Winch

Thanks. I've always used RMG but I have been considering a smaller , lighter winch for the new boat.

 

Trimaran Foiling Configurations Compared

When you get a chance see the new thread "New Trimaran Foilers". http://www.boatdesign.net/forums/multihulls/new-trimaran-foilers-55834.html
Morrelli and Melvin are involved in a new foiling tri that uses more or less the same configuration as a catamaran-an UptiP foil and rudder T foil on each ama.
Thats the second new tri using that configuration-the Exocet 19, under development by Perspective Design(mentioned above with a render here:http://www.boatdesign.net/forums/multihulls/small-trimarans-under-20-a-43650-38.html ---- scroll down) is the first to be announced under 20'. Perspective has recently mentioned doing a 16' version of the Exocet 19.....
For new ocean racers the newest foiler was the MOD 70 converted by Gitanna(now Maserati) with the same configuration-and the first large foiling tri since Hydroptere.
The 100' Macif has a similar configuration but it's main foils are smaller than the MOD 70 and so far no foiling pictures as good as seen with Gitana.
This seems to be a favored configuration these days-the MOD 70 can actually fly for extended periods on just two foils which is fantastic!
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The Fire Arrow configuration is entirely different with an UptiP foil on each ama and a single rudder T-foil and wand controlled daggerboard t-foil on the main hull. The main disadvantage of the Fire Arrow configuration, compared to all of the above, is that it will always fly with three foils in the water- the daggerboard foil unloads and can eliminate induced drag but there are always three foils in the water.
The main advantages(also see post 2342 above) of the Fire Arrow configuration, compared to all of the above, are:
1) the ability to fly the main hull in very light air,
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2) the ability to consistently fly the main hull in wind and waves,
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3) the fact that the main foil can generate downforce that dramatically increases the righting moment of the boat.
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Hopefully, there will be a large version of the Fire Arrow Foil System flying one day to directly compare to the conventional configuration.

 

Fire Arrow Foiling System Testing and Development

I'm having visitors later this week to look at the Fire Arrow so I set it up today. After a while I was looking at it and noticed the stb UptiP ama foil had more AOI than the port-a lot more. Haven't had a chance to measure it exactly and I don't know whether I accidentally hit the foil or what but if nothing changed since the last test sail that was surely slow. May not be able to tell what the story is or why it is like it is.

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PS-a little off-topic but check this out: http://www.boatdesign.net/forums/al...hours-impossible-rescue-55859.html#post778044

 

Foiling!

From "The Foiling Week': https://vimeo.com/163408105

 

Fire Arrow Foiling System Testing and Development-set-up crash!

I had the boat set up for company today and that went well. After they left I took the boat apart. It was sitting on its stand in a rather confined area. In order to allow the stb. ama to be removed I taped the crossarm to the table so that with the ama removed it wouldn't flip. That worked ok for about 5 minutes and while I was putting the stb. ama back in it's normal stowage position I heard a big crash: the half-*** job I did with the tape let go and the boat flipped with the aft outboard planing surface of the port ama smashing hard into a chair. That was actually a good thing because if the chair wasn't there the foils would have likely broken. As it is there is about a 2.5" chip out of the edge of the planing surface that will easily be glued back in place. And there was about a 3/16" chip knocked of the sharp point of the port ama foil-no big deal.
To give you an idea of the force involved: the ama weighs about 5.5 lbs and the CG is about 3.3' from the center of the main hull, so when the tape let go the thing was really moving! Luckily no serious damage. This was the first damage done to this boat from any cause since she was "born"-and was 100% my damn fault.

 

Very Thin Carbon Veneer

The material in the picture is what is going on the exposed balsa deck of the D2. I've also used thicker pieces on the Fire Arrow and D4Z. It is very light and is finished on one side-the other side is ready to be bonded with epoxy. Also available with adhesive already in place. Much lighter than covering with a carbon wet laminate that would need to be finished-once bonded this is finished! I've worked with this before and it is really great to work with. Not limited to use on models-a great way to quickly carbonate almost anything. Not cheap though.
Doesn't do compound curves so what it goes on must bend in one direction only. Also made a mistake in ordering a 4' piece at this thickness-they had to roll it. For some reason when I unrolled it it didn't immediately lay out flat like it should have. Not going to be a problem ,though. But I won't order such a long piece again at this thickness.

Here's a link to the Protec carbon sheets: http://www.protechcomposites.com/categories/Carbon-Fiber-Sheets-%2d-Glossy/Black-2x2-Twill/.25mm/




D2 with the Carbon veneer applied:

 

Fire Arrow Foiling System Testing and Development-Wing Tip Rig

This is an innovation on the Fire Arrow that I have used on other boats as well including the Flyer Cubed and D4Z. The low drag peaked up squaretop was also used on the F3 foiler, America One and Spinnaker 50 RC monohulls and on the 36" Super Scow.(pictures below)
The idea of this shape is to, in essence, increase the span of the main to reduce drag, while at the same time providing buoyancy at the head of the sail to prevent the boat from turtling:




D4Z






Wing Tip Rig Pictures, L to R-1) Flyer Cubed, 2) F3-worlds first production RC sailing foiler,3) America One and S50-first production RC spinnaker boats(set,douse and gybe by radio),36" Super Scow with Trapeze Power Ballast System:

click for better view--

 

Fire Arrow Foiling System Testing and Development

A description of a proposed main foil first conceived of in 2014 with an upside down center asymmetric section. The idea is to create a foil with the same automatic downforce that a wand controlled foil is capable of. Very, very experimental:

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 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 inverted 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 Foiling Week-Newport

See this:
http://www.boatdesign.net/forums/hydrodynamics-aerodynamics/foiling-week-50888-2.html#post784447

I'm pretty excited to see the Unidentified Foiling Object that Steve and Dave Clark have produced!!

 

Variation on the Fire Arrow for Fullsize 14' Tri

I may never be able to do it but I've come to the point where I want to build a small-around 14'- tri that I can sail singlehanded. I've learned a lot about the new foils developed by Hugh Welbourn for the Quant 23 and Flo 1 and they have a lot of potential to be applied to a small trimaran.
For a 14 footer the platform could be 8' wide eliminating folding and any assembly of the amas to the rest of the boat. The foils would extend outboard about 3-3.5' on each side and be fully retractable for trailering. They would not need to be retracted from tack to tack or gybe to gybe.
For use as part of the basic Fire Arrow concept, they have three great advantages:
1) they add tremendous righting moment,
2) they develop vertical lift capable of supporting the whole boat,
3) they don't develop lateral resistance like most other hydrofoils do.
The 14 would use a wand controlled(or surface piercing) main foil attached to the daggerboard and a rudder T-foil. These foils would work just like they do on the Fire Arrow Test Model controlling the pitch of the boat and ride angle of the outboard foils. But their main contribution is facilitating light air takeoff which would be targeted at around 5 mph(4.38 knots).
If the Welbourn type outboard foils were used without the daggerboard foil the whole boat wouldn't fly until 12-15mph of wind because of the great righting moment of the boat. And that's not acceptable to me.

Here are the foils about to be tested on a 51" model loosely based on Dominion(the first tunnel hulled scow) and on the Quant 23 foil system. The 14' trimaran platform using these foils with the Fire Arrow concept would be for the same length twice as wide as this boat + the foils:





D2 with "B" rig: