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Latest surf foil design: Gull wing and other stuff

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Latest surf foil design: Gull wing and other stuff

Postby Jyoder » Mon Mar 04, 2019 12:05 am

Pictured are a bunch of the new-ish surf foils. Are these new elements like the gull wing really more effective? or is it just more fashionable and sleek looking for market appeal. I'll admit, the old flat G10 wings that started the foil craze look sad compared to the new hot carbon curvy sleek hotness, but what changes and new design has really caused the reported performance boost compared to the old traditional foils?

1. Gull wing? That's the s-curve (dihedral/anhedral). What does it do? Anything except look nice and make the foil harder to manufacture?
2. Airfoil? has the "airfoil" really changed much and how? Or, is it mainly another factor, like thinning out the foil and stiffness from carbon?
3. Delta shape? The initial foils had that shovel-shape and now the raved about Onda does too, and looks like the SS infinity series does as well. Does wing sweep really matter in hydrofoils? I've seen some off-brand rectangular wings work great, and the Spitfire canard wings are squarish and seem to do alright.
4. The SS Space skate has Dihedral! what the?! discuss.

Anyway, there's more probably, but I'm just wondering how much we are being bamboozled by marketing and "looks" and how much of all this new stuff is really effective at increasing performance in terms of low end, high end, stability, turning, etc.

Hydrodynamics is a black box in many ways.
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Re: Latest surf foil design: Gull wing and other stuff

Postby ap888 » Mon Mar 04, 2019 12:54 am

They All love to be ridden (they are all sluts) :naughty:

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Re: Latest surf foil design: Gull wing and other stuff

Postby grigorib » Mon Mar 04, 2019 12:58 am

3. Wing sweep. Arrowhead shape. Whatever it is called is a savior from damn seaweed. 633 doesn’t catch any seaweed, but 483 stabilizer behind it - a bunch.
548 was catching good amount of seaweed and 590 - less so.

Not everyone rides where seaweed is a problem but who does can appreciate swept-back wings.

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Re: Latest surf foil design: Gull wing and other stuff

Postby NYKiter » Mon Mar 04, 2019 1:18 am

There may be more going on than you think.....

I believe Moses is using multiple profiles within the span of a single wing....

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Re: Latest surf foil design: Gull wing and other stuff

Postby bigtone667 » Mon Mar 04, 2019 1:47 am

They all look like they are a copy of the klingon "bird of prey" ....

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Re: Latest surf foil design: Gull wing and other stuff

Postby BWD » Mon Mar 04, 2019 6:36 pm

Here's my take based on a modest comprehension of theories and my own experience and "feel"

anhedral gives more stability and makes it easier to turn with a constant radius.
dihedral may make a big sluggish wing more lively, it's rare on small wings because of this.
I think this is because with dihedral, you get more projected area and vertical lift on part of the wing on the inside of the turn as you roll into a turn, instead of a little more on the outside, which would tend to stabilize the roll angle a bit. instead the dihedral could make the wing feel skatey, or if overdone, encourage jacknife capsize/crashing. Coming out of a turn on a dihedral wing, it seems it would take a bit more more roll correction and time before the maximum lift is available from the outside wing part. With a big shovel wing all this might be nice, since the sweet spot of big wings is bigger, and it may be more fun to have the wing be more dynamic.
With a little wing, I don't think you want the center of pressure moving around so much, as you need to be more centered and stable, usually ride faster and crashes are harder.

Wingtips influence drag and vortex shedding behavior. Tips pointed up or down can increase stability and guide the high and low pressure flow together in a way that suits the foil.
I associate tips up with higher speed and concern with reducing drag, personally.
Tips down seem to be common in surf wings and optimized to maintain the high pressure under the wing for lower end performance.
Flat wings with thinner tips, or anhedral wings that flatten or turn up at the tips, let the high and low pressure flow come together in a way that makes riding with a good bit of the upper wing half out of the water more stable. This is fun and can save you in case of errors or choppy water..
Since the average pressure differential would seem to be allowed to fall gradually toward flatter tips, disturbances like surface piercing, chop, yaw changes etc would be less likely to cause a rapid full ventilation and stall crash. in this way flatter anhedral tips could be a little like having narrower tips.

The MFC shape is most interesting, I would guess it provides a little bit of inertia to yaw disturbances but overall it seems fairly flat.

Wing profiles vary, some are pretty constant root to tip, others not. There are benefits to having profiles that add twist toward the tips ("washout") to do with drag and vortex shedding, etc. Simple designs with a constant profile seem to work too though, and probably easier to design and build.
Sweep can let bigger wings have higher AR with less span while keeping the center of pressure in the same place as a smaller wing, so you can swap wings without having to change fuselage or mast position. Sweep can also act like washout.

Anyway, done rambling for now, hope that information is somewhat interesting or helpful. I welcome any reflections or clarification from those who are more educated in hydrodynamics. It's interesting to peek inside that world, rather than keep it as a black box. Gear makers and sellers (assuming they properly understand their products) often tend to dumb it down way too much to really give riders understanding imo. But it can be hard to understand....

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Re: Latest surf foil design: Gull wing and other stuff

Postby grigorib » Mon Mar 04, 2019 6:46 pm

Now to profile question.
Is there any foil manufacturer which actually runs simulations and tube tests on their wings?

Amount of wings/profiles produced would need significant amount of simulation and actual tube testing and I personally get a feeling that the wings are just product of shapers’ minds, hands and gut feeling instead.

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Re: Latest surf foil design: Gull wing and other stuff

Postby Peter_Frank » Mon Mar 04, 2019 7:46 pm

grigorib wrote:
Mon Mar 04, 2019 6:46 pm
Snip...
Amount of wings/profiles produced would need significant amount of simulation and actual tube testing and I personally get a feeling that the wings are just product of shapers’ minds, hands and gut feeling instead.

Can only agree, that this IS how they are made and designed, I am certain :thumb:

But as the feel and dynamics are by far the most important, if you dont race, it is by far the best way :D

Aesthetics are important, just like everything else, so a major often not performance nor "feel" related parameter.

This goes for far more designs than what many thinks, that it is try and feel, and look, besides neck and neck tests, and not based much, or not at all, on quantifiable measurements.

It is not rocket science :rollgrin:

8) Peter

PS: I disagree that sweep is introduced because of seaweed, as then the race wings should sometimes be swept, as they can not get rid of it like we as freeriders can whenever we want.
Sweep has multiple purposes in terms of making the wing more stable, faster turning, and in particular less prone to stalling, on cost of performance.

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Re: Latest surf foil design: Gull wing and other stuff

Postby tkaraszewski » Mon Mar 04, 2019 7:54 pm

grigorib wrote:
Mon Mar 04, 2019 6:46 pm
Now to profile question.
Is there any foil manufacturer which actually runs simulations and tube tests on their wings?

Amount of wings/profiles produced would need significant amount of simulation and actual tube testing and I personally get a feeling that the wings are just product of shapers’ minds, hands and gut feeling instead.
> Is there any foil manufacturer...

Emirates Team New Zealand?

For kitefoils, I don't think even Mike's Lab foils are tested in CFD software (if you know Mike and that's not the case, let us know!)
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grigorib
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Re: Latest surf foil design: Gull wing and other stuff

Postby grigorib » Mon Mar 04, 2019 7:56 pm

Peter_Frank wrote:
Mon Mar 04, 2019 7:46 pm
grigorib wrote:
Mon Mar 04, 2019 6:46 pm
Snip...
Amount of wings/profiles produced would need significant amount of simulation and actual tube testing and I personally get a feeling that the wings are just product of shapers’ minds, hands and gut feeling instead.
Can only agree, that this IS how they are made and designed, I am certain :thumb:
...
It is not rocket science :rollgrin:
..
Unfortunately. If we got wings ran and optimized through SW used by guys who design submarines and props for ships, we'd be a decade ahead by now.
Peter_Frank wrote:
Mon Mar 04, 2019 7:46 pm
...
8) Peter

PS: I disagree that sweep is introduced because of seaweed, as then the race wings should sometimes be swept, as they can not get rid of it like we as freeriders can whenever we want.
Sweep has multiple purposes in terms of making the wing more stable, faster turning, and in particular less prone to stalling, on cost of performance.
I'm not saying sweptback is introduced because of seaweed, but what I know for sure - it helps a lot to not catch seaweed. Both 2013 MHL Lift and 633 arrowhead wings I've ridden handled those flocks of seaweed by far the best than any other wing I rode.
So if there's more purpose to it....I only want more swept back wings and stabilizers!


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