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Tubercle wings and my moulding process

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fluidity
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Tubercle wings and my moulding process

Postby fluidity » Tue Feb 01, 2022 9:37 am

Happiness... Second week of holiday. I've completed several moulds and ready for wind tomorrow to test a new stabiliser and a couple of Axis Black fuselage compatible front wings. Feel like I've come a long way since I started designing foils back around September 2019.

My process:
Design wing (openscad, I do it with formulae controlling the wing's surface)
Subtract a manufacturer's front mast connection at the angle I want the front wing to sit at.
Subtract shear planes to subdivide the part for 3D printing and dowel shapes for rejoining after printing.
Print- This works out around 3.5 days with PLA + and a 0.6mm nozzle, for an intermediate wing size around 1200 sq cm.
Clear my dowel holes with a drill to the precise dowel diameter(I oversize to D+0.3mm but they still needs cleaning).
Superglue the dowels and wing pieces together ansuring alignment of the trailing edges.
Use an orbit sander and around 260 grit to take the highs off the wing.
Bog up any print line cavities, sand and repeat.
Spray with high build primer, sand.
Use food sealing bag and machine to vacuum seal a membrane around the wing, keeping kinks and folds of the bag to a minimum.

Pack infusion mesh, budget glass fbre multiple layers around top and bottom of the wing inside a bigger vacuum storage bag. Set infusion spiral wrap and tube in place to vent into the infusion mesh.
Set resin brake with strip of peel ply on other side from infusion spiral.
Wrap my vacuum hose with paper towels, place at end of peel ply.
Seal resin intake hose.
Apply sealant tape around inlet and outlet, close vacuum bag around sealant, zip closed, test vacuum, fix any leaks.
Mix polyester resin with about 0.8% catalyst for a slow cure.
Place hose in polyester container, release clamp.
Monitor infusion until resin is past wing with a good allowance for the mould's flange.
Give the mould plenty of time to cure.
Debag infused composites.
Drill 2 x mould alignment holes at ends of composite mould.
Trim with a Dremmel to ends and sides of food vacuum bag.
Split the composites into the two wing sides, remove the bagged model.

Fill the food bag texture voids in the mould surface with budget filler or high build paint, allow to cure.
Sand smooth to 400 grit.(no polish).
Apply PVA mould release all over both inside faces of the mould halves.
Allow to dry, repeat if needed.
Use wing model for composites outline template and cut all the pieces out, allowing for tapering at the edges.
I use a lot of unidirectional and now I'm doing thin, high performance wings I use all carbon fibre. However unidirectional won't resist twisting and an exterior impact can split the fibres apart. So use a woven exterior skin and add double bias cloth to clad or space the unidirectional to boost it's robustness.
Epoxy the mould halves and allow to go tacky, trying to keep an even film.
Apply the woven outer skins to each side with overlap to the mould's mating surfaces.
Apply the unidirectional, unidirectional, double bias etc.
Epoxy in pieces of compressible core mat.
Mix up some glue filler with epoxy and ensure that there will be no air voids in the wing.
Close the two mould halves together, screw together with the two locating holes and clamp the rest of the mould's seams together ensuring evenness of the clamps.(I have spring clamps, lever clamps, I've got about 20.
Wait for the leaked out resin to go hard.
Clean off any resin bridges around the mould seams.
Drive in plastic wedges, putty knives to split the mould halves from the new wing.
I've done this for 3 different wing designs in the last week!
Note that the thinner the wing, the more unidirectional you will need. If you're on a budget, consider basalt. It's well priced and goes a dark brown when cured with epoxy. It's similar weight to glass fibre but more smash resistant than carbon or glass.
Also be careful around any mast attachment. When you do up the screws, you should not be squeezing sides together, between the screws ant the mast foot there should be only composite material, nothing compressible.
Attachments
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20220201_174220.jpg
20220130_124519.jpg
20220129_135836.jpg
20220129_135829.jpg
1636690509166 1.jpg
1640996640734.jpg
1640806894292.jpg
These users thanked the author fluidity for the post (total 3):
nemoz (Tue Feb 01, 2022 5:50 pm) • Dontsink (Sat Feb 12, 2022 9:20 am) • JoãoSilva (Wed Jan 10, 2024 9:49 pm)
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fluidity
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Favorite Beaches: Plimmerton
Style: Wave, jump
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Re: Tubercle wings and my moulding process.

Postby fluidity » Thu Feb 03, 2022 10:16 pm

Finally had some wind the last two days and pretty stoked. Got up on both wings, found I needed to swap to a smaller stabiliser to retain control at speed, got a bit more used to not slowing below stall speed of the wing and on day 2 of a 3 day print for my replacement lighter wind wing... Which will be my first to combine tubercles and wingtip twist. It's about half way through and already looking amazing...
Until you understand the bell span load for wing the shape doesn't make much sense but birds do it and for very good reason.

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Re: Tubercle wings and my moulding process

Postby Dontsink » Sat Feb 12, 2022 9:17 am

Wow, incredible work!.
Million careful steps to be prepared and done, makes my head dizzy :).Congratulations.

Do not know if it relates to foil but as a pilot i was fascinated by the work of Al Bowers on the Prandtl flying wing (not the boxwing).
It has more to do with adverse yaw and how birds (albatross) can fly as they do...the end result is a wing with extreme twist.But we use weightshift and not control surfaces so maybe no use for foiling.
https://www.google.com/url?sa=t&source= ... SiXGUjawh1



I know you want to keep your designs a bit underwraps for possible commercial use but please post what you can.Thx!.

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fluidity
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Weight: 115kg
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Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Transitioned from Kiting to Wingsurfing late 2019. Building my own foils from my CAD designs and 3D prints, CNC machine.
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Re: Tubercle wings and my moulding process

Postby fluidity » Sat Feb 12, 2022 11:54 pm

Dontsink wrote:
Sat Feb 12, 2022 9:17 am
Wow, incredible work!.
Million careful steps to be prepared and done, makes my head dizzy :).Congratulations.

Do not know if it relates to foil but as a pilot i was fascinated by the work of Al Bowers on the Prandtl flying wing (not the boxwing).
It has more to do with adverse yaw and how birds (albatross) can fly as they do...the end result is a wing with extreme twist.But we use weightshift and not control surfaces so maybe no use for foiling.
https://www.google.com/url?sa=t&source= ... SiXGUjawh1



I know you want to keep your designs a bit underwraps for possible commercial use but please post what you can.Thx!.
Thanks.
The moulding sounds harder than it is after you get used to it. maybe half an hour to an hour in preparation and then the infusion just needs a bit of supervision. Once you get your head around the consumables, and have all the materials on hand it's great. I'm going to do an axis compatible minimal trim tubercles rear wing mould today and tidy up the mould for my first front wing with the twisty shape(needs to have the Axis mast foot shape bogged into it where the vacuum membrane didn't follow the shape right).

I actually posted that very same Ludwig Prandtl & Albion Bowers, Horton brothers related video link may 24'th 2021 on here viewtopic.php?f=107&t=2407467&start=210 . And then we see 3 months later on here, Triton T1 Monofoil using a monofoil adapted for the bell span load and apparently having some significant success viewtopic.php?f=196&t=2410957 One of their videos shows the foil in it's delivered box, looking like a large Pizza box and I could see the rear wingtips angle up significantly. So I then found another video that shows the foil in a better profile and it was very aparent, they are using the technique. It's most of use with shortest wingspan where wingtip vorticies are most destructive but as you would have seen with Albion's team, they use it to great effect for a high aspect glider as well. One of my wingsurf buddies and I were actually discussing the Triton and thingking it was completely over hyped but then I had the thought to see if they had made a Prandtl R2 influenced design, because that would fit the reported success for a low aspect ratio foil. And they have. I'm not much impressed with their mast mounting system though, there is no sleeve so it's very vulnerable to end loads on the foil stressing the bolts.

I think most of the commercial foil designers are very skilled but the evidence shows they are working with the tools from the master Ludwig Prandtl's first paper, not his second. So I have a bit of an advantage being new to this(year and a half) in not being brainwashed with preconceptions about hydrofoils. And another advantage that I can use CAD algorithms to program some very funky wing shapes. All this stuff is going to be taken for granted in another few years abut at the moment I find it exciting, Manufacturers have been only really competing on shape of the foil cross section in regards to performance.
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fluidity
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Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Transitioned from Kiting to Wingsurfing late 2019. Building my own foils from my CAD designs and 3D prints, CNC machine.
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Location: Porirua New Zealand
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Re: Tubercle wings and my moulding process

Postby fluidity » Sun Mar 06, 2022 12:09 am

Wow.. time has passed and I tried a few different moulding techniques, pretty happy with what I'm doing for prototypes now. Did 3 wings close to the 1100 sq cm mark, a low and high aspect one, then I added to my profile to get the prandtl twist, printed a couple more wings but before doing moulds for both or any carbon, I revised my profile and then printed out an 1145 sq cm wing.

That's my go-to wing now, so long as there are white caps. I put a little concave in the under surface, kept the tubercles but dropped them to a total of 9, moulded it, cured carbon and epoxy in the mould and tried it out.
My intention was not ultimate speed, but better lift for it's size, easy turning(900mm span) and a very easy, low drag flow through wave. I expected a higher stall angle because of certain design aspects.

And it delivered! It's a bit draggier than an Axis 1099 which for me is fine, it wasn't my goal. (It still goes plenty faster for me) But the tapered tubercle design rolls easily, there's no bunny hopping stalls taking off, the transition from slow to stall is very soft and way down on speed. If I breach it (Because I don't get the same feeling as other foils when it's close to breaching) half the time it recovers! Breaching a tip with any kind of speed and others have seen the tip pop out, but it keeps going. And on waves, more than any other foil I've been on, it is super playful and slippery and I'm learning much faster than on anything I've tried before.

I tried a swap to an AXIS 999 with fuse and tail and it was strange, I was stalling a lot, I was struggling to control pitch. Definitely there was speed but I hated the handling. Changed back and it was happiness again. My foil buddy reckoned my foil setup behaved like his old Armstrong (which was a 1500 sq CM) Strangely, his shorter stabiliser with slightly more chord than my longer one, and on his shorter fuselage- didn't make sense to me, It had behaved super locked in, while on my longer fuse, with a lower area stabiliser, had more response to pitch. Since then I changed my own stabiliser to a 280 sq cm shorter design, also tubercles. It's feeling only slightly more locked in but definitely not as much as the Axis. I have more designs in the works, I have a 797 sqcm foil ready to take a mould from that will behave closer to a 1000 in lift but be slightly faster for it's size than my 1145.

And I'm working on a new foil profile. I'm working on pushing past the NACA design limitations to give me the profile shape I want and I want to tweak the Prandtl twist a bit. Maybe another few weeks and I'll have more progress.

I'm 115kg so this foil is carrying a lot :o
Attachments
20220221_173648.jpg
20220206_135945.jpg
20220130_124519.jpg
Last edited by fluidity on Sun Mar 06, 2022 2:18 am, edited 1 time in total.
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Dontsink
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Re: Tubercle wings and my moulding process

Postby Dontsink » Sun Mar 06, 2022 12:53 am

They look great, and the perfo you describe at 115kg is quite a success.Very good job.

Lately i have been very impressed with the GoFoil GT clips of tip breaching, that step design seems to deliver the goods.
Maybe it is not that surprising, a step is a channel/fence and abrupt twist transition and both of these seem to be the key to prevent full ventilation from the tip sucking air.

I am very happy that this concepts you and others are experimenting with make foils glidey without loosing the "fun" factor.
The trend towards simply thinner and higher AR foils was a bit boring to me, performance with a big price in lost playfulness.
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fluidity (Sun Mar 06, 2022 1:54 am)
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User avatar
fluidity
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Posts: 657
Joined: Sat Mar 19, 2016 11:20 pm
Kiting since: 2015
Weight: 115kg
Local Beach: Ngati Toa, Plimmerton, Titahi Bay, Waikanae, Petone, Seatoun, Lyall Bay, Eastbourne, Lake Wairarapa
Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Transitioned from Kiting to Wingsurfing late 2019. Building my own foils from my CAD designs and 3D prints, CNC machine.
Brand Affiliation: Designer of hydrofoils and many other things.
Location: Porirua New Zealand
Has thanked: 46 times
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Re: Tubercle wings and my moulding process

Postby fluidity » Sun Mar 06, 2022 2:15 am

Dontsink wrote:
Sun Mar 06, 2022 12:53 am
They look great, and the perfo you describe at 115kg is quite a success.Very good job.

Lately i have been very impressed with the GoFoil GT clips of tip breaching, that step design seems to deliver the goods.
Maybe it is not that surprising, a step is a channel/fence and abrupt twist transition and both of these seem to be the key to prevent full ventilation from the tip sucking air.

I am very happy that this concepts you and others are experimenting with make foils glidey without loosing the "fun" factor.
The trend towards simply thinner and higher AR foils was a bit boring to me, performance with a big price in lost playfulness.
We all look at performance a bit differently. Back about 6 years ago when I was still new to kiting I watched many promotional and also test riding videos of kite boards. Eventually I found a video of a newish guy riding an Ocean Rodeo Mako. No flashy stuff of how it looked in the air, but I loved the look of it in the waves. I didn't realise, but another local here had one. Anyway, I designed and made something similiar, rounded ends, very deep concave and I loved it. The most striking thing about the board though, I had been watching the guy who had the genuine article at our Waikanae beach, slashing it around in the waves and assumed he was levels above my ability. When I rode my own similiar board though, that same performance and slashing around on the waves came to me too. Though rider makes a big difference, sometimes gear is huge too. Eventually I made a quite small deep concave board with diamond ends and that became my favorite. We have a lot of turbulence in our local winds which favor high speed glide to coast through the lulls. However when you look at foilers like wake thief, for his purposes it's high efficiency and glide at human pumpable speeds. For me, locally, I'll end up designing a bunch of foils, mostly around my own purposes and then either get bored or adapt them for a manufacturer keen to sell what I'm making. I'm not bored yet, still only into wing foiling a year and a half and still a lot to learn out on the waves. I've also found it interesting that I can get good lift performance in a smaller foil. Some drag increase relative to a less lifty profile, but it has implications for manufacturing cost too. Getting more lift in a smaller foil costs less in materials.

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fluidity
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Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Transitioned from Kiting to Wingsurfing late 2019. Building my own foils from my CAD designs and 3D prints, CNC machine.
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Re: Tubercle wings and my moulding process

Postby fluidity » Sun Mar 06, 2022 3:20 am

Dontsink wrote:
Sun Mar 06, 2022 12:53 am
Lately i have been very impressed with the GoFoil GT clips of tip breaching, that step design seems to deliver the goods.
Maybe it is not that surprising, a step is a channel/fence and abrupt twist transition and both of these seem to be the key to prevent full ventilation from the tip sucking air.
I am very happy that this concepts you and others are experimenting with make foils glidey without loosing the "fun" factor.
The trend towards simply thinner and higher AR foils was a bit boring to me, performance with a big price in lost playfulness.
Just checked out the gofoilGT (and the EZ) you mentioned and yes, quite startling steps that give a similar performance enhancement to mine although I have a very smooth progressive change rather than a crude step. Watching the mackiteboarding review https://www.youtube.com/watch?v=ssxS7Kkv4aY he talks about good pumping. I'm so far only on the 4'th session on my wing. I did notice the first time ever that I pumped it, it took off, really accelerated. Don't know if I've now just got used to it but was dramatic at the time. Some times I think I'm going way too slow and I'll stall, or I do stall(softly) and one pump on the wing and I'm up and accelerating again. It's been a wing full of surprises even though in general terms I got what I was aiming for in my design. GoFoil, Triton and my own designs are all giving this different rider experience for those who describe the feel.
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Re: Tubercle wings and my moulding process

Postby faklord » Thu Mar 31, 2022 9:03 am

fluidity wrote:
Tue Feb 01, 2022 9:37 am
Happiness... Second week of holiday. I've completed several moulds and ready for wind tomorrow to test a new stabiliser and a couple of Axis Black fuselage compatible front wings. Feel like I've come a long way since I started designing foils back around September 2019.

My process:
Design wing (openscad, I do it with formulae controlling the wing's surface)
Subtract a manufacturer's front mast connection at the angle I want the front wing to sit at.
Subtract shear planes to subdivide the part for 3D printing and dowel shapes for rejoining after printing.
Print- This works out around 3.5 days with PLA + and a 0.6mm nozzle, for an intermediate wing size around 1200 sq cm.
Clear my dowel holes with a drill to the precise dowel diameter(I oversize to D+0.3mm but they still needs cleaning).
Superglue the dowels and wing pieces together ansuring alignment of the trailing edges.
Use an orbit sander and around 260 grit to take the highs off the wing.
Bog up any print line cavities, sand and repeat.
Spray with high build primer, sand.
Use food sealing bag and machine to vacuum seal a membrane around the wing, keeping kinks and folds of the bag to a minimum.

Pack infusion mesh, budget glass fbre multiple layers around top and bottom of the wing inside a bigger vacuum storage bag. Set infusion spiral wrap and tube in place to vent into the infusion mesh.
Set resin brake with strip of peel ply on other side from infusion spiral.
Wrap my vacuum hose with paper towels, place at end of peel ply.
Seal resin intake hose.
Apply sealant tape around inlet and outlet, close vacuum bag around sealant, zip closed, test vacuum, fix any leaks.
Mix polyester resin with about 0.8% catalyst for a slow cure.
Place hose in polyester container, release clamp.
Monitor infusion until resin is past wing with a good allowance for the mould's flange.
Give the mould plenty of time to cure.
Debag infused composites.
…..
Interesting process! I’m tempted to give it a go.
A couple of questions:
1) What do use for “food sealing bags”? All those that I have seen (including rolls) have a patterned (embossed?) inner surface, I assume to help trapped air escape (similar function to infusion mesh). Maybe a thin, lay flat polythene tube?
2) Why use an infusion process to make mold rather than a normal, wet layup (and maybe vac bag?)

Thanks for sharing.

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fluidity
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Posts: 657
Joined: Sat Mar 19, 2016 11:20 pm
Kiting since: 2015
Weight: 115kg
Local Beach: Ngati Toa, Plimmerton, Titahi Bay, Waikanae, Petone, Seatoun, Lyall Bay, Eastbourne, Lake Wairarapa
Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Transitioned from Kiting to Wingsurfing late 2019. Building my own foils from my CAD designs and 3D prints, CNC machine.
Brand Affiliation: Designer of hydrofoils and many other things.
Location: Porirua New Zealand
Has thanked: 46 times
Been thanked: 91 times

Re: Tubercle wings and my moulding process

Postby fluidity » Fri Apr 01, 2022 8:01 am

faklord wrote:
Thu Mar 31, 2022 9:03 am
Interesting process! I’m tempted to give it a go.
A couple of questions:
1) What do use for “food sealing bags”? All those that I have seen (including rolls) have a patterned (embossed?) inner surface, I assume to help trapped air escape (similar function to infusion mesh). Maybe a thin, lay flat polythene tube?
2) Why use an infusion process to make mold rather than a normal, wet layup (and maybe vac bag?)

Thanks for sharing.
I've switched now. I run a packing tape rim around the edge on both sides. No pattern and I apply mould release to the wing.

Infusion- it's really fast and reliable. Pulling the resin through fibres(and infusion mesh) I can do both sides at once in cheap ISO polyester with most of the stink trapped in the vac bag, take it out the next day, drill locator holes, trim the excess fibreglass off, split from the mould and it's done except for surface cleaning up.
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