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Wing surface area definitions?

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Peter_Frank
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Wing surface area definitions?

Postby Peter_Frank » Thu Jul 29, 2021 3:53 pm

I wonder how different brands measure surface area?

Thickness, camber, profile (giving a semi useless number "volume" but better than nothing) is of course what dictates the lift and drag, but if we look merely at the wing area manufacturers give us:


Gong t.ex has three measures I can see on their webpage, an example from two different wings with numbers in parenthesis:

Projected area (1734 / 1520 cm2)
Upper surface area (1912 / 1550 cm2)
Felt area (1900 / 1600 cm2)

But what is "felt" area???

If it is a fictive number for the overall lift of a wing, it is difficult, as would consist of at least area and profile and sweep and AR, and is dependant on aoa.

The difference is between 5 and 10 % on above numbers, maybe not a lot - but still interesting.

How does other brands measure area?
SABFoil?
F-One?
Others?

I know it is not that important, but maybe some knows how a specific brand measure area?

8) Peter

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Re: Wing surface area definitions?

Postby Dwight » Thu Jul 29, 2021 10:32 pm

In the early days a few brands used projected area. So projected area on my Axis foils is what I use when comparing to other brands.

I could see Gong coming up with home built calculation factor using projected area and wing volume to make a perceived felt area. That kind of make sense to me. Higher volume is going to be a thicker foil, so more felt area, given two foils with same projected areas.

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Re: Wing surface area definitions?

Postby Peter_Frank » Fri Jul 30, 2021 12:28 pm

True, about the home built calculation.

But in the example above with the two wings, the first one is the thick one, and the second one the thin one.
With less sweep and higher AR though, but a lot thinner profile.

So if it was based on thickness/volume, Then one would think the "Felt area" should be the same or more than the Upper surface area, but it is a tad smaller.
On the second thin wing, Felt area is bigger than Upper surface area, so it can not be based on thickness (alone), but could be based on AR and sweep?

Projected area...... (1734 / 1520 cm2)
Upper surface area. (1912 / 1550 cm2)
Felt area............. (1900 / 1600 cm2)

Seing this, I wondered how other brands measure area, as many wings are quite curved down, and some has extreme thickness.

8) Peter

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Re: Wing surface area definitions?

Postby Kamikuza » Fri Jul 30, 2021 1:51 pm

No chord or AR? Thickness is handy too, with all that you can make an educated guess about how it'll feel...

Axis is printed on the wing:

Image

You get width, chord and AR on rear wings...

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Re: Wing surface area definitions?

Postby gmb13 » Fri Jul 30, 2021 1:58 pm

I personally think Volume (cm3) / Span (m) gives a decent number of comparison. Espacially for low end.

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Last edited by gmb13 on Sat Jul 31, 2021 10:28 am, edited 1 time in total.

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Re: Wing surface area definitions?

Postby Dwight » Fri Jul 30, 2021 8:57 pm

I’m going to make some guesses based on my experiences

Projected area...... (1734 / 1520 cm2)
Upper surface area. (1912 / 1550 cm2)
Felt area............. (1900 / 1600 cm2)

Let’s assume that 1900 felt are is lower than 1912 upper surface simply because of poor efficiency and drag.
Let’s assume that 1600 felt area is higher than 1550 upper surface due to efficiency of a more modern foil.

It is kind of crazy to try making up Felt Areas for foils. We are advancing as riders and boards are advancing, making it possible to ride pretty small, thin foils that make lots of Felt Area at the speeds we ride now.

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Re: Wing surface area definitions?

Postby Peter_Frank » Fri Jul 30, 2021 11:08 pm

Kamikuza wrote:
Fri Jul 30, 2021 1:51 pm
No chord or AR? Thickness is handy too, with all that you can make an educated guess about how it'll feel...

Snip...

You get width, chord and AR on rear wings...

Yes, span is also labelled, and max thickness and volume, on Gong wings.

You dont need (max) chord or AR, as it is implicit when you got span and area :thumb:

Eventhough they mistakenly calculate AR as span divided by max chord, which is totally wrong...
It is span divided by mean chord, meaning span*span/area equals AR.

And agree dwight, it seems silly to try to make a "Felt area" calculation, for so many reasons :wink:

8) Peter

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Re: Wing surface area definitions?

Postby papasmerf » Sat Jul 31, 2021 2:46 am

gmb13 wrote:
Fri Jul 30, 2021 1:58 pm
I personally think Volume / Span gives a decent number of comparison. Espacially for low end.

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gunnar, slightly off topic but have you been on the north sonar 1250ha vs 1450ha vs 1500r vs 1850r wings for wingfoiling? if you were 87 kg's and very decent at kitefoiling,,, but a beginner winger,, which would you prefer? inland lake with + or - 2 foot windwaves and lots of chop, 15-30 mph normal wind conditions.

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Re: Wing surface area definitions?

Postby ieism » Sat Jul 31, 2021 6:45 am

I think these guys sell so many wing sizes and types, that they decided to add how "big" a wing felt compared to others in their lineup.
Most people would add another gong wing to their setup and this should make selection easier maybe.

I don't think they calculated it.

I could be wrong, but I've been on the phone with them one time and they do talk about how a wing feels compared to others more than specs when you talk to them. Maybe for a beginner it's a good way of working, I don't know.

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Re: Wing surface area definitions?

Postby gmb13 » Sat Jul 31, 2021 10:32 am

papasmerf wrote:
Sat Jul 31, 2021 2:46 am
gmb13 wrote:
Fri Jul 30, 2021 1:58 pm
I personally think Volume / Span gives a decent number of comparison. Espacially for low end.

--
Gunnar
gunnar, slightly off topic but have you been on the north sonar 1250ha vs 1450ha vs 1500r vs 1850r wings for wingfoiling? if you were 87 kg's and very decent at kitefoiling,,, but a beginner winger,, which would you prefer? inland lake with + or - 2 foot windwaves and lots of chop, 15-30 mph normal wind conditions.
Hi,

This is a great example of how Surface are does not work for comparing wings. The HA1450 has a lot more low end than its area suggest. The HA1450 is closer to the 1850R for lowend takeoff speed, and pumps a lot better. The HS1250 is close to the 1500R in Takeoff speed.

For Flat Water Inland conditions I would go for the HA1450. However, the HA are a lot more loose than the R series. So if you want a more stable and easy ride, then go for the 2200R or 1850R and wth new longer 700 Fuselage



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