Self adjusting foil - the future

Which is why Olympic class boats are always one (or 10) steps behind the latest technology. By the time IQfoil is in the 2024 games it will be old technology. The same thing will happen as with Rsx. People that want to race will end up stuck with old tech.

Reminds me of electronic gear shifting on bicycles, when it first came out I thought it was a gimmick, but then the top 3 out of 5 riders used it on the tour deFrance couple years ago.

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aeroegnr said..

Sandman1221 said..
Reminds me of electronic gear shifting on bicycles, when it first came out I thought it was a gimmick, but then the top 3 out of 5 riders used it on the tour deFrance couple years ago.

Hah you're making me wonder if they can snake an antenna through the bolt area and adjust trim with a bluetooth watch or something...

Well on the bike eshifters, and the foil, a computer decides what to do based on the program being used. So on the bike you can have it setup so you only use one shifter to change gears front and back, computer decides which derailleur(s) to engage to increase or decrease speed based on the program.

Didn't i76 get touted with a self adjusting feature?
It surely IS pitch stable.

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Ian K said..The bicycling analogy is more akin to geared bikes and fixies. Some people still ride fixies just because they can. But for early take off and top speed flaps will soon be the go.

Ian - how about a Variable-Sweep wing (foil)

Swept for speed/carving/high wind and straight for early-lift/glide/low wind ??

I like the idea and don't think it will dampen skill required to race. The problem is to race in 6 knots you need a lot more lift than you do with a 20+knot board speed. Meaning at both ends performance is compromised. Having adjustments such as flaps or retracting wings makes sense. I was thinking of a foot operated setting like the old adjustable mast tracks but technology has come so far speed and altitude sensors can make a good prediction for you! Nice work.

All the hip thrusting in the world can't change a foil from a low speed/high lift configuration to a high speed/low lift (and drag) configuration. The adjustable flaps can do that, which is why normal foils won't be able to complete with them.
Gliders have had a standard class in racing for many years for exactly this reason. Fixed foils will never be as fast as a foil that can change it's camber.

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LeeD said..
Didn't i76 get touted with a self adjusting feature?
It surely IS pitch stable.

After struggling a bit to transition from Slingshot to Starboard foils, I understand the "self adjusting" claims about the i76. I mostly used the i84 and TC68, but these also have the "self adjusting" feature. Basically, they are easier to control when accelerating, and seem to have reduced lift when getting close to the water surface, which makes avoiding breaches easier.

Of course, it could be that my impression is wrong, and that my control problems are all due to incorrect setup and not enough experience on Starboard foils. After a couple of hundred sessions, it's easy to forget how things were when starting out.

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berowne said..
I like the idea and don't think it will dampen skill required to race. The problem is to race in 6 knots you need a lot more lift than you do with a 20+knot board speed. Meaning at both ends performance is compromised. Having adjustments such as flaps or retracting wings makes sense. I was thinking of a foot operated setting like the old adjustable mast tracks but technology has come so far speed and altitude sensors can make a good prediction for you! Nice work.

That's a valid point. Airplane wings at takeoff come to mind. Old airplanes like double wing planes (biplanes) with fixed wings come to mind. I don't know much about airplanes, but every one I've ever been adjusted wing shape for take off and landing.

One question is how much weight and cost is added by the adjustment system.

The TC68 didn't have any of the "self correcting" features, which was really just washout and a reflexed foil shape. Both of which are really well known in aerodynamics (like since the 30s) and both have significant efficiency penalties.

As for variable camber foils I think anything with a linkage or hinge will have too much drag penalty to win races. The moment some materials which change shape in response to electrical current (been played with for two decades in aircraft) or have very well engineered flex hit the scene will be a game changer.

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Grantmac said..
...As for variable camber foils I think anything with a linkage or hinge will have too much drag penalty to win races. The moment some materials which change shape in response to electrical current (been played with for two decades in aircraft) or have very well engineered flex hit the scene will be a game changer.

They went pretty fast in the AC boats.


As for controls, I would think something similar to SRAM eTap - which uses wireless for bike shifting. Put some buttons on the boom and the trim can be adjusted in flight. I don't think it takes much away from the skill level any more than all the buttons in an F1 car do. When you are at the pointy end, skill will still count.

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Paducah said..

Grantmac said..
...As for variable camber foils I think anything with a linkage or hinge will have too much drag penalty to win races. The moment some materials which change shape in response to electrical current (been played with for two decades in aircraft) or have very well engineered flex hit the scene will be a game changer.

They went pretty fast in the AC boats.


As for controls, I would think something similar to SRAM eTap - which uses wireless for bike shifting. Put some buttons on the boom and the trim can be adjusted in flight. I don't think it takes much away from the skill level any more than all the buttons in an F1 car do. When you are at the pointy end, skill will still count.

The AC foils have a lot more room to hide the linkage and hinges. The smaller scale you go the harder that is.
For the very small deflection foils need you can probably get away with a carbon or glass live hinge with no moving parts. There is at least one full sized aircraft design doing the same with aluminum.

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Grantmac said..


The AC foils have a lot more room to hide the linkage and hinges. The smaller scale you go the harder that is.
For the very small deflection foils need you can probably get away with a carbon or glass live hinge with no moving parts. There is at least one full sized aircraft design doing the same with aluminum.

Moths are similar scale and have managed the mini hardware.

While you're at it you might as well watch the "how to foil gybe' video. From 2014!

That's possibly the main reason for marking the target ride height on the Moth centreboard. The mechanical connections are set to match that corresponding wand angle with neutral flap - minimum drag.

But once the moths/windfoilers go "fly-by-wire" it'd be much simpler and any set up would be possible. For windfoilers maybe just full flap for take off and marginal wind and then a completely neutral flap setting - handing it all over to rider weight shift if the mast is between 15% - 85% immersion. At 15% immersion the actuator should be able to step in and avert a breach quicker than you can throw your weight forward?

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gregwho said..Flaps can not only go positive to increase lift (& drag) at low speed but they can also go negative to reduce lift & drag at speed. This is why a flapped foil will out-perform a fixed foil - it will operate efficiently at a much wider range of speeds.

I agree - that's where I see the possible advantage of flaps - varying the lift and drag of the wing.

Maintaining level flight with weight movements is simple with practice, even in swells.