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

Thanks for the info!

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Here is a list of the modifications made since the First Foiling video on July 24th,2014. Number 10 added 10/17/14. I've included page and post references. 2015 testing will start in early June:
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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.
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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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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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D4Z update

Radio box "loaded" and all systems tested( rudders, sheets, F&A ballast, Side to Side ballast), cover, hatch and mast step installed. All that left to sail is running the winch lines and fitting the already complete rig:


click-

 

D4Z and Fire Arrow ready to Test!

D4Z ready for rig test and "dress" pictures( platform+rig+foils) tomorrow if wind is light enough and ready to sail soon after that. Fire Arrow ready to re-start testing June 2.

 

D4z(ac 4.8rc)

First test rig:
click for best view-

 

Looking good.

 

Thanks!

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Pictures from last year(misfiled/"lost") :

 

D4Z Foils (Batfoils)

D4Z with very experimental batfoils in place. The batfoils are surface piercing T-foils twisted from 0 degrees at center to +3 degrees at the tips. Each main foil also has an intrinsic 15 degree flap(iFlap) on each tip(whose area may be reduced in testing). The idea is to have low speed takeoff and reduced drag at higher speed. Because each main foil is canted bottom out 10 degrees it only requires a 4 degree angle of heel for the boat to fly the windward main foil, reducing drag a lot, automatically.
click for best view-

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Very interesting comments by John Casey sailing(foiling) in the Florida 300. Most people will remember the uninformed anti-foilers comments on how weeds would just kill any hydrofoil-even though it was pointed out the vertical daggerboards could also be a problem. Now read this from the front page:

"The real story of our day came courtesy of large clumps of sargasso lining up on their march to shore, just hanging out waiting for us. Yes, they play havoc with our daggerboard boats, but a unique and surprising thing happens when the FCS foils through the weeds; they slice right though them. What we thought was going to be the biggest hindrance on this flat water leg from Islamorada to Key Biscayne was actually helpful to us, as the slower boats had to clear their boards far more often. We called our day ‘mowing the lawn’."

 

Fire Arrow Foiler / MPX Foil System Testing and Development

Getting close to resuming testing. Since last year the primary testing was in 5mph(4.34knots) or less and the boat did very well, this year will be done only in stronger wind. The original rig was designed to be reefable by rolling the bottom of the sail, but there is no need for that this year so I removed the lower panel. That allows a 20.5" section of the mast to be removed, lowers the CE of the rig and removes 598.5 sq.in. of sail area(4.16 sq.ft.). Total sail area last year was 3390 sq.in.(23.5 sq.ft.) and this year will be 2791.5 sq.in(19.4 sq.ft.).
That's an 18% reduction in total sail area.
The removed panel can be added back if required, but, from a testing perspective, I don't think it will be necessary.

Pictures-the first two pictures show the main reefed by removing the lower section. The last two show the lower panel rolled up and retained by velcro.

 

Fire Arrow Foil Configuration

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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I'm getting ready to test a new type of surface piercing T-foil that may work as well as a wand controlled foil-only simpler. If the tests on the D4Z pan out then a version of the foil will be tested on the Fire Arrow as a direct replacement for the wand controlled main foil.
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 this year.
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.(see pix below).
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The short version of the final test video from last year showing the boat foiling in very light air(5mph max) :
https://www.youtube.com/watch?v=7Mok3d4KiMI

 

One Metre trimarans

If you are interested, I have just finished three new boats, two 1 metre tris and a new Mini40, and I now have some action of the boats in gusty conditions. It is here:

http://youtu.be/Tjy8zr1fRig

There are two different positions for the foils on the boats. In the windy part of the video, 01 (white yellow purple hulls) has the foils in the aft position, intended to give better manoeuvrability but less foiling stability, whilst 02 (white red blue hulls) has the foils further forward. Both appeared to work well, and there are brief glimpses of both boats foiling. I started off with the top suit on 02 which was a mistake - should have gone with number 2 rig form the start, but the hook in the ball bearing swivel on the jib tack gave way on a gybe, not the first time I have experienced this.


The boats were fun to sail and did hydrofoil. Whilst not elegant, fitting the foils outboard of the hulls is simple and relatively easy to move fore and aft. You need to be more accurate with rig choice and definitely not overpower them. But they tacked OK in a breeze. In the light wind video clip at the beginning they are using just a centerboard.

The new Mini40 - a Firedragon from Roland at rcsails.com - has foils that are connected to servos in the floats so in theory I can get some down-force working on the windward foil, but the kicker broke on the boom before I had started to see if it was going to be effective. . I think the fore and aft position of the foils is OK as it also tacked quite quickly.

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RC Foiling Tri's

Great work, Ian thanks for sharing it here! You must have a lot of boats by now. Are you still using thick foils-what thickness as compared to chord?

Ians video:
https://www.youtube.com/watch?v=Tjy8zr1fRig&feature=youtu.be

 

Perth man, really impressive, especially your skill in the conditions, what really impressed me was the forgiving nature of the boats, nose stands and high sides but always recovery. No doubt your skills as well ! The foiling is definitely getting there, some impressive runs, well done.