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

Summary of Fire Arrow Testing and Development since First Sail

It's interesting to note that this boat has been sailed a total of 1hr 50min with a total of 26 minutes and 38 seconds of sailing video uploaded to YouTube.
In that very short period of time, a radical foiler design using two different foil systems in a combination never before seen in the history of mankind was taken from light air testing to full flying foiling. This is a sort of Index so that if the reader is interested in reading about development milestones they can do so easily from this page:
Sailing History--( youtube channel: https://www.youtube.com/channel/UC6S7JPG1d2uZ91lqt7ObyIw )

1) First Sail-6/17/14, page 91, post 1356. Total video time: 10:55. Total estimated sailing time:25 minutes.
video- https://www.youtube.com/watch?v=X0AHD34_-8c
video- https://www.youtube.com/watch?v=74KEpcmgCh8
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2) Second Sail/ Foil Assist-6/26/14,page 93, post 1393. Total video time 4:42. Total estimated sailing time: 20 minutes.
video- https://www.youtube.com/watch?v=FF7cy8AoFnU
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3) Third Sail-7/10/14, page 102, post 1522. Total video time:2:58. Total estimated sailing time:30 minutes.
video- https://www.youtube.com/watch?v=LmXCdAlo4mk
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4) Fourth Sail/ Full Flying Foiling-7/24/14, page 106, post 1589. Total video time: 7:48. Total estimated sailing time: 35 minutes.
video(long version)- https://www.youtube.com/watch?v=4YBOEolFqiE
video(short version)- https://www.youtube.com/watch?v=7Mok3d4KiMI
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Milestones of Development: (click on page above)

1) Reefing, page 102, post 1527
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2) Ama foil mods, page 104, post 1554,
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3) i-flap description, page 105, post 1561,
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4) Pictures of ama, main and rudder foil mods, page 105, post 1575
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5) Pictures of painted foils, page 106, post 1578,
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6) Summary of changes/fixes before first full flying video,page 106, post 1581,
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7) Changes made since first full foiling video, page 109, post 1626,also see page 111, posts 1659, 1661 and 1662,
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8) Removal of i-flap on port foil, page 109, post 1628 and 1630,
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9) GCD and Reefing, page 109, post 1631,
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10) Cutting mast for reefing, page 109, posts 1633-34,
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11) Updated Specifications, page 110, post 1639,
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12) Pictures of reefed rig, page 110, post 1642
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Next-God willing and the creek don't rise a knockout all foiling video......

Pictures: the boat and Coach Dan Burkes Pirates Team logo:

 

Fire Arrow Foiler / MPX Foil System Testing and Development --Partial Span Flap

Well, I've spent a few hours tonight researching partial span flaps. My original rational in using such a foil was because of the very thin foil sections I am using. The flap would tend to jam because of foil flex so on the F3 I reduced the flap to a bit over a third of the foil span-and it amazed me how well it worked.
Which is why I've used the same concept on the Fire Arrow(with a bit longer flap just added), but the drag such a flap can cause has concerned me-especially since the flap overhangs the foil.
Tonight I found an answer that I had considered but found no support for the idea anywhere-until tonight.

Left is a flap with an endplate I found while researching, right is Fire Arrow main and rudder foil-mainfoil with the short flap. And ,far right, the foil with the extended flap-flap is now 47% of span . This is the configuration used in the foiling video:

 

Fire Arrow Foiler / MPX Foil System Testing / Experimental Flap Endplates

Today I made up two experimental endplates out of thin carbon sheets-each endplate is made of two pieces. They are glued on to the end of the flap. I would have preferred to use a piece of flexible material glued to the flap in the plane of the foil but that will have to wait-I had nothing here that would work.
So I'll see how these work out if I'll even notice.
I also glued on and faired in a strip of mylar on the bottom of the foil to streamline the gap between the foil and flap and that worked real well.

Click for best view:

 

Fire Arrow Foiler / MPX Foil System Testing and Development

I made a mistake in post 1379, page 92. I apologize that it took this long for me to catch it! Thanks to Jeff for placing a note on the original post to reference the correction below:

 

Fire Arrow Foiler / MPX Foil System Testing and Development

On Sunday(hopefully) I'm going to try a new toy, I mean tool-a Velocitek Speed Puck. I bought it at the same time as I bought the useless Gone Pro-and guess what-this thing still works. Only one disadvantage in trying it: it weighs .65lb which is equivalent to 29lb on the full size boat, in addition to the three 175lb people and 26 lb of drinks already on board. It's 3% of the total model weight. Would you take a 29lb GPS speedometer on your 19 footer? I'm going to also use the iGOTU GPS tracker and maybe if nothing else I'll be able to calibrate the IGOTU tracker. I've lost confidence it it because it gives speed with altitude and the last three times came up with ridiculous altitudes like 65'! So I'm not sure the speed is accurate. If it's marginal conditions I'll just use it for a few minutes.
The thing is attached with a lanyard and velcro:
click:

 

I stumbled across an old thread that had some interesting foil discussion.

Over 9 years ago, T Speer explained limitations of partial span flaps

It would seem that partial span rectangular planform flaps will be very high drag anytime the flaps are providing any real lift.

Post 410 and 412 in: http://www.boatdesign.net/forums/sailboats/foiler-design-2447-9.html

I wonder if a flap that tapers down to a very small chord fraction on both ends could reduce drag

 

Fire Arrow Foiler / MPX Foil System Testing and Development

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Thanks , Paul-I think I may have read that. It's like all of design-many compromises. For the thin sections I'm using, based on research by Graham Bantock and others on models, there was no other way 14 years ago on the F3 and the design was even more apropos on this boat with its 21lb weight.
There are ways to make the flap work with much less drag but I can't do that now. Maybe the endplates will help.
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PS-Paul, I just read those posts again-I hadn't remembered that I asked Tom about endplates on the flap.... I asked him about a flap that was 1/3 of the span-the Fire Arrow flap is 47% of the span but the foil is fairly high aspect at 9.75/1.

 

I mentally noted that some faded memory of Tom's 2005 words may have had some influence on your change from 1/3 to 47%.

 

Fire Arrow Foiler / MPX Foil System Testing and Development --Partial Span Flap

Well, I increased the mainfoil area from 50 sq.in to 84 and the span from 23 to 29". I was stuck with the flap chord because of the position of the pushrod so I had no alternative(that I could see) but to increase the flap span. I was very concerned about how that would affect the flap movement but the very thin mylar I use for the hinge still worked well with slight bend. But it was a concern to extend that flap, believe me. Dr. Bradfield told me about his experience with flap hinges on the Rave: the foils had to be machined(they were aluminum) to allow the hinge pin to not bind when the foil flexed. I also got a Moth mainfoil from John Ilett that used a resin impregnated Kevlar hinge which would slightly bind at max load-there would be a "bump" as the flap crossed neutral.
PS-even with the extra span the flap is still only 23% of the mainfoil area.

 

Amazing stuff Doug! I'm an RC turbine and ducted fan guy so I can appreciate the work your putting in! Lot hard to do these things on almost a microscopic level sometimes! Haha so as of late I'm rediscovering my love of boats, and building on a more normal scale! Forgive my aquatic learning curve, have a firm grip aerodynamically speaking but hydro is all new to me! But my question is along with the plates and skegs what effects would tips or even simple washout have on foils? On a aero wing washout allows thinner faster wings raised stall speeds, and tips kinda same deal but with less drag pentalties. Any of those principles applicable with what your working on?


Barry

 

Oh also, for telemetry and logging have you ever messed with eagle tree systems! There small light and very accurate! with inboard and real time tracking. I have one of there systems with "Waas" GPS that's deadly accurate past 200 mph. Even has bi antenna so even if inverted at 220 I get gps speed and correct inboard alt.

Barry

 

Fire Arrow Foiler / MPX Foil System Testing and Development

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Barry, welcome to the forum -and thanks! Washout would have no benefit on my foils but the port ama(outside hull) foil uses washin. The angle of incidence of the foil slowly increases from just after the radius to the tip so that the AOI at the tip is about 3 degrees greater than the portion close to the radius. That allows for high lift to start with but the tip of the foil will break the surface reducing the higher lift drag-same principle on the I-flap( but more high lift drag when immersed).
The stb ama foil uses what I call an "i-flap"("intrinsic" flap) which is a foil with a 15 degree flap carboned to it.(see picture #4). Both foils had the flap on the first full flying foiling video, but I realized that I should have tested the foils with just an increase in area before doing the flap. So tomorrow we'll(Dan and I) sail with two different ama foils.See the post at the top of this page for links to the video's and milestones achieved so far in testing.
I believe the design of any foil tip is important-that's why mine are all raked so that the trailing edge of the foil is longer than the leading edge.

Pictures-click for best view-L to R- 1) illustrates washin, 2) ama foil waterline at low speed/takeoff, 3) ama foil waterline at high speed-highlift/high drag portion of foil emerges from the water(see #5), 4) picture of the i-flap from underneath, 5) Boat flying with lee ama foil tip emerging, 6) ama foil with i-flap tip,7) top and side views of port ama foil. Both the i-flap foil and the foil with no i-flap look the same in this view:

 

Ooohhh, ok gotcha, in actuality the whole foil is washout really. Combined with foil section of course. And gotcha on toe in, that makes sense for sheer tracking. In airplanes it would incidence which stops bobbing up and down in a neutral angles. Very cool stuff!

Barry

 

Fire Arrow Foiler / MPX Foil System Testing and Development

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Thanks again, Barry! Not really-there's washin on the lower portion of the foil only. Sort of the opposite of what you see on an airplane wing......

 

Fire Arrow Foiler / MPX Foil System Testing and Development

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I'm interested in their stuff-I need accurate speed in real time-can't afford anything right now, but I'm hoping to replace the Gone Pro and add speed telemetry next year.
This is what I found: http://www.eagletreesystems.com/index.php?route=product/product&path=63&product_id=58