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

Fire Arrow Foiling System Testing and Development

For those keeping track here is the situation with the boat testing as of now.
The boat will next be tested with shorter daggerboard and rudder and shorter rig. The reefed rig is probably good up to 15 + esp. w/o the jib. Hope to be able to get more video soon. This post is a "re-broadcast" for those interested in the status of the Fire Arrow w/o reading the whole thread:

 

Fire Arrow Foiling System Testing and Development

Here is an updated list of the modifications made since the First Foiling video on July 24th,2014. Number 11 added 7/18/2015-see bottom of previous page for more on #11. I've included page and post references. 2016 testing may start as early as late March depending on Dans schedule-God willing and the creek don't rise:
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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 which was rolled as part of the reefing system has been completely removed for this years testing.
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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) The daggerboard and rudder were shortened 6"-see post 2100 for more detail. This reduces draft making the Test Model much easier to launch.
It also reduces drag and slightly increases righting moment by shortening the heeling arm.
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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 compare 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 full battens help?
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6) Is there a noticeable effect on boat speed, tacking or pointing attributable to the reduced daggerboard and rudder areas?
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Foils! (continued)

And now surface piercing/planing foils for the Dominion 2-HW-just pulled:

 

Light air foiling

As anyone will know that has paid any attention at all to this thread I have been a proponent of light air foiling as critically important for RC and fullsize foilers in order to present the public a boat that flys throughout the wind range-not just in medium or strong wind. My first foiler design, the F3 foiled in a 5mph breeze as has the Fire Arrow on its very first day of full flying.
Just tonight I found that Quant boats, the builder of the first keelboat foiler has publicly stated that they consider it very important to be able to fly in light air and that they expect the boat, with its new taller rig ,to be able to start foiling in a 5 kt breeze! As far as I know,they are the first fullsize foiler manufacturer to recognize the importance of light air foiling! Very cool....

http://www.boatdesign.net/forums/sailboats/quant-23-foiler-scow-53468-3.html

 

Partially Planing Foil(s)

Here is a shot of the fullsize Q23 illustrating its main foil partially(if not fully) planing-one of the unique characteristics of that foil design.
The second shot is of the Fire Arrow on a reach with the ama foil partially unloaded and maybe planing:

 

Fire Arrow vs Aussie 18-power to carry sail

For the first time, in this very long thread, I'm looking at the Righting Moment of the Fire Arrow compared to a well known Skiff.
This is a comparison of the fullsize version of the Fire Arrow to a version of the Aussie 18 Skiff. I'm not even using the maximum RM possible for the Fire Arrow but her "fast cruise/daysailing" configuration.
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Take a look at Bethwaites sketch of an Aussie 18 below. Then look at the sketch showing an oversquare tri-in this case using the Fire Arrow dimensions. Both the tri and skiff are the same length and for this example will each have three crew at a total weight of 540lb. The CG of the skiff crew is at 15' from the center of buoyancy of the boat. The CG of the crew on the Fire Arrow is 14' from the center of lift of the leeward foil since they are all sitting just 3' to windward of the center of the boat.
But the weight of the skiff and its rig do not add a thing to its RM whereas the CG of the hull and rig of the Fire Arrow are 11' from the the center of lift of the lee foil and that means:
1) Max Skiff RM=8370 ft. lb.
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2) Fire Arrow RM =(see A & B in Fire Arrow Sketch below)
A) 450lb hull/rig at 11'=4950ft.lb+
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B) 540lb crew at 14'= 7560ft.lb =
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C) TOTAL Fire Arrow RM= 12510ft.lb or 1.49 times the RM of the Skiff! And that's with the crew sitting just on the windward side of the cockpit and with no downforce from the main foil. Much more power to carry sail without even using Max righting moment.

SKIFF RM illustration:



Fire Arrow RM illustration:

 

RC Foiler Rudder Foil AOI Adjustment

I did this sketch tonight to help a guy on another forum with an experimental RC boat and also in case I need angle of incidence adjustment by radio on the new boat. It allows small AOI adjustment w/o interfering with the rudder movement. A version of this system would work on a fullsize boat as well.Could also work on the Fire Arrow:

 

Fire Arrow Foiling System Testing and Development

It's interesting to reread Bill Beavers Moth paper on the actual measured drag on Moth T-foils-rudder and daggerboard. Note that the speed at which testing was done is 20ft/sec(13mph/11.3 knots/20.9kph) :

 

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Just found out that the very first sailing catamaran foiler(Gilruth,1938) was designed to take off at 5knots!!
More here: http://www.boatdesign.net/forums/mu...oiling-catamaran-1938-a-54980.html#post764431

 

Aero Drag Reduction of Sailboat Rigging

Just found this posting of yours Doug while looking thru some google images. Looks like a looong subject thread.

I'm wondering if there are more positive responses to your call for help with this drag reduction effort. On this page of the discussions it appears as though a number of respondents dismissed the problem.

I'm interested in some simple methods to reduce the drag of the 'bare mast' of my aftmast rig. Some sort of 'flexible splitter plate' idea seems most appropriate?

 

splitter plate

Brian, I'd think the problem would be changes in the apparent wind direction that cause the flexible splitter to generate lift/drag. Maybe some way to rotate the thing?
I'm not going to try anything until the basic testing is compete but I'm convinced it could be just as important on the model as it is on a Moth.

 

Wild weather

Some wild weather last weekend

Resulted in quite a few bits of broken boats but lots of fun too.

https://www.youtube.com/watch?v=IRZKonDOYag

The black & white One Metre tri is the first out of our plugs. The Mini40 is using new foils form Dave Creed, made from RG65 fins with a curved, tapered, trailing edge

 

RC Foilers

Good stuff! Are you going to start producing foiler models?
UPDATE: Though I haven't heard from Ian, I found out that he is going to produce a one meter foiling tri. Best of luck, Ian!

 

RC foil T/c ratio

Ian, what's t/c ratio for your newest foils? Once you had said you were using fairly thick foils-are they thinner now?
Mine are about 9% but I'm considering going to 7 or 8% if I can given the loads...

 

On my first Bucc 24 I used 6% for my "supersonic", foil. Worked a treat, as Edmond Bruce said it would.