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Latest surf foil design: Gull wing and other stuff

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

Postby Peter_Frank » Mon Mar 04, 2019 9:44 pm

Dont think it is that simple....

I havent noticed much or any difference in this regard whether wings are swept or not :wink:

As here it is always on the mast the seaweed catches, so might be it is on the surface here.

Where in other spots and types of seaweed, it is also a bit below the surface maybe.

I honestly think it makes a huge difference WHAT type of seaweed is most common in your location.

8) Peter

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

Postby Jyoder » Mon Mar 04, 2019 11:38 pm

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.
See this is the kind of postulating I question because it sounds right and can think the same kind of things but what do we really know And where’s the data? Water doesn’t compress like air so there are some fundamental differences in the medium that means we can’t just use “aero” thinking for “hydro”, right?!

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

Postby Jyoder » Mon Mar 04, 2019 11:50 pm

and I personally get a feeling that the wings are just product of shapers’ minds, hands and gut feeling instead
This is my suspicion as well. Granted, they must be doing enough R&D to make some progress but how much is it data-driven and how much just serial “build and ride”?

But i’m Biased, of course. I’m frustrated that foils are so damned expensive and there are so many different wings available it’s getting hard to choose. I want to be told that simple flat cheap G10 or plywood core Diy wings have a chance of competing with expensive big brand carbon wings if we just get the aspect ratio, shape, and profile right, doh!

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

Postby Flyboy » Tue Mar 05, 2019 1:56 am

I have just started foiling. I already have a confusing variety of wings to choose from: an anhedral molded fibreglass "free ride" fin from Zeeko, the G10 Zeeko Carver wing which is completely flat, heavy & was considered "large" ... until the newer giant surf fins came out, & a very light, dihedral carbon wing from LP with elegantly downward swooping tips. LP is about to release a line of (what looks to be) completely flat carbon wings - very much less sexy than the FRS wings. It's all pretty confusing. Either it matters a lot ... & everyone's been getting it wrong for a number of years ... or it ALL works perfectly well & it really doesn't make much difference .. or ... ?

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

Postby bragnouff » Tue Mar 05, 2019 2:15 am

The Zeeko Spitfire wings are flat, their wingtips are square, thick and blunt (and safer to hit), and as far as I'm concerned, they work a treat, and have handled a shitload of abuse.
At some stage, absolute performance takes a back seat to convenience, safety, and production costs.

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

Postby Flyboy » Tue Mar 05, 2019 3:10 am

bragnouff wrote:
Tue Mar 05, 2019 2:15 am
The Zeeko Spitfire wings are flat, their wingtips are square, thick and blunt (and safer to hit), and as far as I'm concerned, they work a treat, and have handled a shitload of abuse.
At some stage, absolute performance takes a back seat to convenience, safety, and production costs.
Yeah, the Spitfire wings are very basic looking. It's the miracle of foiling that anything works, but in fact, everything seems to "work". Even those crude DiY wings. "Performance" has become a difficult thing to pin down as foiling has moved away from its race-oriented beginnings. Slow is the new "high performance". :-?

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

Postby FrederikS » Tue Mar 05, 2019 9:30 am

Most skip the simulation and tank testing due to cost, this is still a very small market.

If you look at designs operating in similar Reynolds numbers with some of the same design characteristics and you manage to select appropriate foil profiles you can easily arrive at a solution that sails pretty well.

Then you can play around with out-wash, various types of tip vortex mitigation, anhedral / dihedral. All the principles are thoroughly described in literature so if you are on a limited budget it is probably just easiest to build and sail. Some things are of course easier to integrate than others, but that is pretty much up to the builder, process, and budget.

I think looks are beginning to play a bigger role as the bigger brands are coming in. There are so many design choices in those foils that effectively counteract each.
Last edited by FrederikS on Tue Mar 05, 2019 11:04 am, edited 1 time in total.
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Re: Latest surf foil design: Gull wing and other stuff

Postby Wazza KiteFoil » Tue Mar 05, 2019 10:24 am

FrederikS wrote:
Tue Mar 05, 2019 9:30 am
Most skip the simulation and tank testing due to cost, this is still a very small market.

If you look at designs operating in similar Reynolds numbers with some of the same design characteristics and you manage to select appropriate foil profiles you can easily arrive at a solution that sails pretty well.

Then you can play around with out-wash, various types of tip vortex mitigation, anhedral / dihedral. All the principals are thoroughly described in literature so if you are on a limited budget it is probably just easiest to build and sail. Some things are of course easier to integrate than others, but that is pretty much up to the builder, process, and budget.

I think looks are beginning to play a bigger role as the bigger brands are coming in. There are so many design choices in those foils that effectively counteract each.
OH

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

Postby slowboat » Tue Mar 05, 2019 10:54 am

Flyboy wrote:
Tue Mar 05, 2019 3:10 am



..........It's the miracle of foiling that anything works, but in fact, everything seems to "work". Even those crude DiY wings. "Performance" has become a difficult thing to pin down as foiling has moved away from its race-oriented beginnings. Slow is the new "high performance". :-?
This is the critical point. Since kiters hijacked high lift wings (originally designed for wave riding without kites), performance is just about lift while not having too much drag and being able to turn reasonably fast. So probably true that it all works fine. I look more for lightness and stiffness which just feels better when riding, and durability as I hate seeing my stuff fall apart after a short time.

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

Postby grigorib » Tue Mar 05, 2019 7:48 pm

slowboat wrote:
Tue Mar 05, 2019 10:54 am
...
Since kiters hijacked high lift wings (originally designed for wave riding without kites)
...
We had bunch of large wings until 2014-2015. Then race appealed to manufacturers as a primary discipline and the rest of us were missing large wings dearly (read BraCuru's wondering comment on keeping his old 4xx wing).
People weren't mistaken by riding 135/150 Lift wings and other companies caught up really fast.
Last edited by grigorib on Fri Mar 08, 2019 5:56 pm, edited 1 time in total.


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