New High Performance Monofoilers

sure no prob. Next weekend at KYC!

The R class experience with foils seems fundamentally different than most other applications. Their web site shows off lots of details on the collaboration involved with the development. It would seem they have set up the molds for the foils to be available such that the entire class will have access if the individuals can come up with the raw materials. The use of foils seems to be an opportunity for those with older boats to get back into a more competitive position. Those involved indicate stability is actually improved (more on this below). Other plusses were noted and the biggest drawback I saw discussed was launching issues.

Most of those promoting foils focus on the reduced wetted area as the big gain. Give me a flat water surface and plenty of wind and I do not need foils to get low water friction. I see the opportunity for smoother travel through chop as a bigger potential advantage in real world conditions for small mono hulls. As real innovators (like the R Class crowd) get better with foil controls, they should be able to make real improvements in both pitch stability and roll stability. This should both reduce friction with the water and allow for more efficient sail operation.

In somewhat lighter air, there seems to be a range where a small amount of foil lift can reduce overall friction by getting more of the hull out of the water. For this to be a net gain, the foil must be operating very efficiently. This is probably not a focus area at this time, but there is no reason it can not be worked out.

For classes that allow either foil or non-foil, the final challenge is the really light air conditions. I do not see how a main foil in the normal position will ever be a winning configuration in light air. Designing the hull and foil to allow retraction with the foil becoming just a bump on the bottom of the hull would be an option. This would be combined with a much smaller (and less loaded) rudder foil and a small separate “light air only” dagger board to give the crew a boat with all the choices they could want.

There are racing classes where boat innovation is not allowed or where it is only just tolerated. These classes are great for what they are and competing at this level is probably where most sailors want to be. However, there will always be those who push for something better. For now, foiling is one area where the potential seems to be there and more than a few are striving to make it happen. Seems to me a "boat design forum" would be a place where people would colaborate & make constructive remarks to support this kind of development rather than all of the negative junk and general fussing (on both sides).

Mirabaud 2010

Faster than a Moth at Weymouth! http://www.boatdesign.net/forums/sailboats/mirabaud-lx-2010-a-33020.html

reference post #38, this thread....

R Class-on-foils Update

The class continues blazing new territory in two person foiling. The R Class is the ONLY two person monofoiler class in the World:

The 2010 Leander was a fantastic showcase for the foiling R's. The breathtaking speed, sailability and obvious fun of the foilers has generated a lot of interest and heralds an exciting resurgence in the R Class. Reliability is getting better with the foils and boats surviving a gruelling Leander Trophy and five race Sprint Series unscathed.

Merde made massive speed and stability improvements throughout the contest by moving closer to TheVirtual's setup. They are now starting to show the potential of the older boats on foils.

One of the important parts of the project has been to make hydrofoiling an affordable and practical part of R sailing for anyone in the fleet no matter what boat they have and how old it may be.
We have a specially built oven and foil moulds for squadron members to easily build their own set of foils. There are also people who have already built foils who are happy to help those who are new to this and let them know how it's done. If you don't want to build foils yourself then you can hire someone within the squadron to build them for you.

More here: http://www.rclass.org/

video: foiling gybe with spinnaker(!): http://www.youtube.com/watch?v=N5cBTP7vI10&feature=related
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what's an r class skiff?
Extreme performance, light weight, skiff style, development dinghy class in the truest sense (see the rules for details).

Length 3.9m (max)
Hull no minimum weight (typically 29-35kg painted), 1.4m minimum width
Construction Unrestricted (typically ultra lightweight Carbon/Foam)
Rig Unrestricted - typically two spreader pre-bent carbon spar
Foils Unrestricted
Working Sails Area is restricted 13m2 - construction and rig plan are unrestricted - ie. wings, pocket luff, rotating masts are all acceptable
Kite 20m circumference resulting in a 30-36m2 surface area
Crew 2 (minimum) on trapeze



click on the image and then again on the resulting image:

Not so sure about this

Doug:

It is somewhat admirable that you relentlessly promote this "progress" on the foiling front. In regards to the "R" class, things just don't seem the same - the wild, bucking, barely controllable beasts have been tamed into silent, gliding, high speed sedans that are faster, quieter and comparatively drama-free. Kind of like turning in your 65 Corvette with the conventionally aspirated 327 small block and now driving a 2010 Infiniti G37 sport coupe. In every measurable way, the Infiniti is a better, safer and faster sports car - but in another it is soulless automaton that sucks the life out of you.

I was in awe for years watching the insane R-class boats sail in breeze - now I'd rather watch slower boats that look like they are going faster. The foiling R's aren't skiffs anymore in the Aussie-Kiwi sense - they are foilers.

Just my opinion, I'm sure you will disagree.

--
CutOnce

Here's one for you, Doug, yet another free thinking young Frenchman with his foiler adapted Bangladesh monohull: http://www.voilesetvoiliers.com/

Go down to La video a la Hune, Tara Tari - and all done on a shoestring.

Gary Baigent said:

Here's one for you, Doug, yet another free thinking young Frenchman with his foiler adapted Bangladesh monohull: http://www.voilesetvoiliers.com/

Click to expand...

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Foiler, huh?

Nice, Gary. Really funny bit.

High Performance Monofoilers-altitude control

One very interesting development over the last year (and sure to be repeated on other boats) is manually controlled altitude that by-passes the wand on the 26' Mirabaud. The guys on the boat say it is particularly useful in choppy water where the wand can create a real bumpy ride.
I've foiled my own 16' boat using a manual control system* and despite some problems I feel it is a great way to foil and I think it has great potential in racing foilers. Here is a post from last year quoting TomSpeer on manual control of the mainfoil flap:
(* also have used a manual system on two different rc boats with great success )

Doug Lord said:

For those designers and experimenters interested in looking closer at manual altitude control here is a comment from Tom Speer ,post 355 of "Foiler Design". And I would like to hear from anyone with on the water manual foil control experience and/or experience with modelling it by computer or rc testing :


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" If you look at the conditions for stable flight, the forward foil must have a relatively higher heave stiffness than the rear foil, and the rear foil must cause a greater change in pitching moment with a change in angle of attack than the forward foil. This is why wand feedback to the forward foil and a fully submerged aft foil work so well together. The heave stiffness of the aft foil is virtually zero, so it does all the job of stabilizing the craft in pitch. The forward foil then is totally responsible for controlling the craft in heave.

Manual control of altitude via the forward flap makes sense, since that is the surface that really controls heave. But the big difficulty is having enough control power to handle both the dynamic change in lift needed by the control system, and being able to trim out the change in lift due to speed. With direct gearing between the wand and flap and the boat flying at a constant pitch attitude, the only way for the control system to trim out the increase in speed with lift is to deflect the flap upward, and because of the gearing between flap and wand, this means flying higher.

If the boat is trimmed bow down as the speed changes, then the reduced angle of attack will compensate for the speed and the boat can fly at its design height with the foil centered (on average). One way to get this pitch trim is with manual control of the stern flap. The speed changes less rapidly than flying through waves or even being hit by gusts. So pitch trim with speed makes sense for manual control.

It might be possible to get some automatic speed trim by clever manipulation of the hinge moments on the rudder flap. Aircraft use a device called a "down spring" to augment their speed stability. A spring with a low spring constant is used to apply a near constant nose down force to the controls. This has to be trimmed out with the trim tab. But the force from the trim tab depends on speed. So as the speed increases, the tab effectiveness increases and moves the elevator in the nose-up direction. This makes the aircraft climb, which reduces the speed.

The opposite could be applied to a hydrofoil. If the rudder flap were deflected upward with a spring, increasing speed would reduce the deflection. This would make the boat trim more bow down, reducing the flying height in much the same way as the manual pitch trim described above. You could also divide the rudder flap into two parts - one driven by the spring and the other under manual control.

Naturally, the spring force would control the amount of automatic trim change. It's better to get the force from deflecting a long, weak spring a lot, than by deflecting a short, stiff spring. This makes a bungee cord ideal for the purpose.__________________
Tom Speer "

Click to expand...

Mirabaud manual control lever:

Doug Lord said:

...I've foiled my own boat using a manual...

Click to expand...

Please stop telling all these reasonable folks that you foiled your own boat, Doug. You haven't produced any proof at all that it actually did anything except take a short tool around some flat water lagoon in virtually no wind... and then you scrapped it unceremoniously, foisting the hull onto a guy at a windsurf school.

Produce something that speaks to proof on the topic, other than your highly personalized and biased statement and we'll be able to acknowledge that your boat actually did foil with you on it. Photos, video, film, etc., will do nicely.

Paul B has some very interesting quotes from you right after your non-event that came directly off these pages. Shall I ask that he post those again, just so this claim is put in proper perspective for any new members of this forum?

At this point it is unconfirmed, but I've been told there is a new two person high performance monofoiler being developed in Switzerland. There sure is room for such a boat-the only 2 person full flying foiler now is the R Class. The I-14's(pix below) backed off allowing flying and instead use "foil assist" with a rudder foil only. But David Luggs 14 was the first two person monohull bi-foiler in history AND the first bi-foiler with manual altitude control.

David Luggs I-14 circa 1999:

R Class foilers

Here is a video sent to me by Rob Denney:

http://www.youtube.com/watch?v=iUFTcCmwCco

Thanks, Rob-next maybe we'll see a foiling proa!

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R Class news: (1/11/11)

http://www.rclass.org/seasons/2010/5-foilers-on-the-water