Author Topic: Gong's different approach to High Aspect.  (Read 5862 times)

Fishman

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Gong's different approach to High Aspect.
« on: January 02, 2022, 03:39:26 PM »
Gong released their Fluid "HA" wing called the Fluid "Tall". It's not rally a HA compared to most brand's with Ratios in the 9:1 area. So seeing that these Fluid Tall's hover below 6:1 AR was not really what I expected when last summer Gong said they had a HA ratio wing in the works.
But a closer look shows a different kind of High Ratio that may be the key to what makes these "TALL" wings something really special, in a deferent kind of way.
Not high Span to Cord ratio, but high Area to Volume ratio. Yep a super thin wing that still has lift.

I just received a couple of Gong Fluid Tall version wings. And yeah they have some real wow Factor to them.  The thing that strikes me, is how thin they are, especially the trailing edge. Really impressive to look at. So much so my family was thinking I "went over the edge", as I had the XLT wing on the couch next to me most of Christmas day. I even passed it around pointing out the concave section, as if a non foil geek would be as impressed as I was, LOL.  First impression riding this wing from this novice winger, is they do fly as good as they look. Fluid is the perfect name for this wing as that's probably the best word to describe how it flys.

I think the magic in this wing come from the "HOLLOW" as Patrice would say. It's the concave under-side that takes up the rear 1/3 of the wing bottom. It's hard to imagine that the hollow section would create any additional lift for the cord,  but do i'd think it adds to the AOA and direction of flow which in a unconventional way adds to the lift. (I don't know this, just guessing about how this all works) I don't know if anyone else is doing this concave underside, or if Patrice came up with this on his own, but ether way I think it's very clever and out of the box thinking. I thought this wing's "hollow" would compromise some lift, but after using it, the lift is not a problem at all. It's really more lift than i expected from such a thin wing, and I even had to move the foil back in the tracks to get things right. I will be ordering the smaller sizes to see how small I can go with these wings.

If you look at the smaller Fluid MT, it has 950cm area, it's 12mm thick, and only has 0.6 litters of volume.  Next to a real High Aspect ratio wing like Axis 899 that has a area of 850cm and a volume of 0.69 liters you see just how thin these Fluid Tall's really are.  For comparison here are some Area per volume number.

Gong Fluid XXLT = 1,065cm per liter (1907cm area / 1.79 liters of Volume) AR-5.82
Gong Fluid XLT   = 1,196cm per liter (1555cm / 1.3) AR-5.84 ----- 1.6mm thick
Gong Fluid LT     = 1,313cm per liter (1235cm / 0.94) AR-5.89 ----- 1.4 cm thick
Gong Fluid MT   = 1,583cm per liter (959cm / 0.6) AR-5,90  ----- 1.2cm thick
Gong Fluid ST    = 2,157cm per liter (712cm / 0.33) AR-5.97    ----- 9mm thick!!!

Axis PNG 1300 = 903cm per liter (1712cm / 1.895) AR-9.94
Axis PNG 1150 = 840cm per liter (1778cm / 2.116) AR-9.94
Axis ART 999   = 1,193cm per liter (1038cm / 0.871)  AR-9
Axis ART 888   = 1,231cm per liter (850cm / 0.69)  AR-9
Axis ART 777   = 1,389cm per liter (730cm / .0.54)  AR-9

  I know ratios like these don't mean all that much, but I do think it is another piece of the puzzle that  contributes to what makes a good and efficient wing.
Anyway Bravo to the Gong team. Now get some LT''s back in stock so I can get that one too.
« Last Edit: January 02, 2022, 03:45:04 PM by Fishman »
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Dwight (DW)

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Re: Gong's different approach to High Aspect.
« Reply #1 on: January 02, 2022, 06:09:46 PM »
Some Kane tails have the under side like that.

surfcowboy

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Re: Gong's different approach to High Aspect.
« Reply #2 on: January 02, 2022, 06:38:23 PM »
Argh, Fish, I was just about to consider moving to another brand to go HA and here you are raving about the fluid.

I love my curve XL, truly. About to start riding the L-T more. But before I disvest maybe I should grab one of these. L-T to start at my size? I like wide span stable wings.

What tail are you using nowadays?

But the real question is how much weight do the carbon masts drop off these rigs? With a big wing and 85cm mast my rig feels like it's half my body weight. Fine if you don't travel or walk long distances (I love it at the lake, hate it when there's a long beach to cross or a hike to the surf spot.)

I'm reluctant to drop another $1,000 for a mast and new wings when that would get me into a nice used HA rig. Maybe I should commit heresy and get a Cedrus and have him make a Gong adapter just to make the gear heads cry.

But the Fluid is tempting hmmmm... Maybe I should sell some wings and swap things around.

Fishman

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Re: Gong's different approach to High Aspect.
« Reply #3 on: January 02, 2022, 08:17:46 PM »
Hi Cowboy, One guy mentioned the new v2 100cm carbon mast and aluminum fuse together weights 3300 grams. The v2 mono block was 2800 grams.  I don't remember the weight on their shorter carbon mast.
I hear they'll also have a Pro fuse at some point in the future.

These fluid wing all came in light in weight. Unlike the veloce with the heavy first run thing.

I'm playing around with tails and lately I like the smaller X-over. But I'm 6'4" and like the feedback and extra length is just a little more comfort like training wheels but you can still crank it hard when you want. And still playing with the small surf and 45 kite/fast. But with the Fluids wings it will take some time to figure what works best for me. Id like to get some other stabs but the next shipment isn't till February...

I think Christian (Solent foiler) is you size. He like his Fluid LS and his Axis 999. I imagine he will pick up a MT or LT if he hasn't done so already. He has tried a lot of gear so I'm looking to his or David thoughts are on these Tall Fluids.

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Califoilia

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Re: Gong's different approach to High Aspect.
« Reply #4 on: January 02, 2022, 10:34:40 PM »
Here's a little side-by-side of some comparable Gong to Axis wings size wise, and their ARs just for the fun of it.

The Gong "Fluid Pro - L" at 81cm, 1200cm², 1.8cm thick for a volume of 1.1L is the same length as the Axis BSC "810" at 81cm, with a projected area of 1022cm2, and volume of 1.28L. This gives the Fluid Pro an AR of 5.47, and the 810's AR is 6.42 for comparison.

The XL Fluid Pro has a 91 cm wingspan, 1500 cm², 2.0 cm thick for a volume of 1.54L, which is the same length of the Axis PNG 910b at 91cm, with a projected area of 1218cm2, and volume of 1.48L. This equates to a 5.52 AR for the XL Fluid Pro, and a 6.8 AR for the Axis 910b.

Also to note, the Axis 1150 has an AR of 7.74, and not 9.94 as mentioned in the first post...so it's much easier to ride (more forgiving) than a true HA wing like the 999, 899, or 799 all with ARs of 9 plus.

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Dwight (DW)

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Re: Gong's different approach to High Aspect.
« Reply #5 on: January 03, 2022, 08:31:17 AM »
Maybe I should commit heresy and get a Cedrus and have him make a Gong adapter just to make the gear heads cry.


These might already fit Gong.

https://www.nolimitz.com/foilmasts


surfcowboy

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Re: Gong's different approach to High Aspect.
« Reply #6 on: January 03, 2022, 06:25:37 PM »
Thx for the info. Yeah, Fishman I like pushing harder on a bigger wing too. I'm not going to crank a fast turn anytime soon and I like the resistance. Though we will see what happens as I move to a smaller front wing.

I'm using the new curve 45cm stab with the upturned tips, so pretty close to you there. Am I just being a wimp riding these big wings and tails? I'm having fun but man it seems like everyone is on wings half the size. I wonder what I'll progress to liking eventually. Hmmm.

Solent Foiler

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Re: Gong's different approach to High Aspect.
« Reply #7 on: January 04, 2022, 04:45:27 AM »
Hiya folks! I've not yet got any Fluid T's, but I have been riding the 899 (early Christmas present to join the 999) a lot over Christmas/New Year. But the best Christmas present was two weeks of mild windy weather! Forget how many days in a row I've been on the water!

As Fishman said, I love the LS. It's an amazing daily driver for someone my size, having a decent low end, and the most fantastic, intuitive control, with no real limit on carving ability / manoeuvrability on the Fluid 40 stab. For carving hard downwind it's in it's element, especially powered up. Linking hard carve after carve does create drag, so some power is nice to keep the speed up. It glides reasonably well going straight, and I could catch and pump some bumps on it, but that's not its natural home. The other feature it has, is that you do get more front foot pressure the faster you go. Not a weird or awkward amount, but when really powered up carving hard through chop going downwind, I would prefer to be on a smaller foil.

I got into the 999 because I wanted to do more bump riding downwinding, and then the 899 to maintain that amazing glide but with better turning, and without that increase in front foot pressure with speed. I'm really debating with myself whether to get the 799 too now...

I didn't go for a Gong option because I was really keen to try these 'proper' HA foils, having had the Veloces in the past which I had enjoyed a lot but kinda knew what they were about. Perhaps the T's do step up performance again, I'm confident they probably do, but I'm not convinced they'll have the efficiency of the proper HA foils. That's not a criticism - just a statement based on my understanding of the physics and where I think Patrice has designed these foils to fit in the compromise options he had to make.

You just have to pick the tool that you think best suits your style and needs, and at the moment I'm digging that glide... Perhaps I'll swing back towards the aggressive carving in a while, and I'll get a smaller Fluid. I don't know which though - the MT is pretty close to the LS, so probably the ST (but that volume looks really small!) or the M (missing the T aspect ratio). To my eye, the 799 does have some nice looking area and volume numbers. #speculation
I'm 5'10", 66kg riding:
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Gong Fluid L-S, XXL-S on 85cm and 65cm mast
Takuma RS 5.1, 4.3, 3.5

Fishman

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Re: Gong's different approach to High Aspect.
« Reply #8 on: January 04, 2022, 09:25:33 AM »
Cowboy, I think you might regret selling your setup without at least trying the T's. It must be nice to have a used market like California does. I look at your SoCal craigslist stuff and get jealous.

Califoilia, Thanks for catching that, I copied and pasted with the intent to fix those Axis AR ratios but forgot. Edit timed me out.

Solent Foiler, thx for your insite. It would be interesting to compare the LT to the 999 or the 888 and the MT.  That 0.3 volume on the ST seems like a kite only option, or maybe a big wave thing, who knows. To bad these things cost money, LOL.

Fluid LS is 1,080cm / liter (1124 / 1.04)
Fluid LT is 1,313cm / liter (1235cm / 0.94)
ART 999 is 1,193cm liter (1038cm / 0.871)

Just food for thought stuff. If the main appeal of the high AR wings is the glide. Which is mainly due to lower "drag to lift" relationship. Then which is the bigger cause of drag? The cord of the wing, or the volume of the wing?

In aircraft this is kind of settled with guiders and their small cords, But I've never seen a plane with a concave underside of a wing. Flaps extended is the closest thing in aviation, and that doesn't seem the same as what Patrice did here. Both flaps/concave and the glider wing span do compromise speed. And since we want speed, and glide, and maneuverability... Certainly interesting how things progress. Can't help but wonder how many more ways are they going to come I with to get me to happily spend more of my money on this addiction, LOL.
« Last Edit: January 04, 2022, 09:28:00 AM by Fishman »
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Dontsink

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Re: Gong's different approach to High Aspect.
« Reply #9 on: January 04, 2022, 03:02:02 PM »
It is hard to find info on "undercambered" wings, i.e. wings with a concave lower surface.
Most of the info i have found is related to RC planes.

In general an undercambered wing will provide more lift,create more drag and lower the stall speed vs an equivalent flat undersurface foil profile.

So you can kind of "trade" foil thickness for undercamber which seems to be what Patrice is doing.

An undercambered foil will also move the center of lift to the rear and increase the forward pitching tendency.

Thx for posting this, it is very interesting, IMHO it shows that it is still early days in wing/surf foil design and the optimal shape is not obvious yet,  tubercles,steps,winglets ,undercamber...so many variables and combinations to be tested (with our money :)  )

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Re: Gong's different approach to High Aspect.
« Reply #10 on: January 04, 2022, 05:53:19 PM »
The Wright Flyer had a curved underwing.  :)

Fishman

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Re: Gong's different approach to High Aspect.
« Reply #11 on: January 09, 2022, 12:26:50 PM »
The Wright Flyer had a curved underwing.  :)

I probably should have been clearer.
The front 2/3 is convex, like most normal foils, then the rear transitions to concave.  I guess you could say it's a drawn out "S" like bottom.

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Fishman

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Re: Gong's different approach to High Aspect.
« Reply #12 on: January 16, 2022, 01:36:58 PM »
Found the name of this air foil mentioned on a GoFoil thread. Apparently they use it also on there new RS foils, and maybe there GT foils too.
Supercritical airfoil.
 https://en.m.wikipedia.org/wiki/Supercritical_airfoil
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Dontsink

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Re: Gong's different approach to High Aspect.
« Reply #13 on: January 16, 2022, 01:43:49 PM »
Found the name of this air foil mentioned on a GoFoil thread. Apparently they use it also on there new RS foils, and maybe there GT foils too.
Supercritical airfoil.
 https://en.m.wikipedia.org/wiki/Supercritical_airfoil

Mmm, they do look similar but very different foils with very different goals.
Supercritical wings are designed to delay or reduce the effects of supersonic shockwaves in air.
We are playing a very  different ballgame.Very low speed, through water...

tarquin

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Re: Gong's different approach to High Aspect.
« Reply #14 on: January 16, 2022, 09:50:45 PM »
Don't know if this is similar but the Naca 63412 foil has been used for ages in sailing and human powered foilcraft.

 


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