Wing profile info for backyard hydrofoil builders

[PrfctChaos]

Hi,
I am following this thread with a great interests. Lots of great info, thank you! I just got into foiling myself (on slingshot hover glide nf2) and thinking that at some point I might end up printing a different foil that would fit into slingshot fuselage.

Did anyone consider 3d printing a foil with polycarbonate instead of PLA/PETG? This would no longer require laminating with carbon sheets. If you google for “Introducing Javelin’s 3D Printed Hydrofoil Project” you will find a report from 2017 where someone printed a polycarbonate foil, but I haven’t seen results of their tests.

Hey mate, I'm pretty sure you'll still need to wrap the print with few layers of laminate at least for surface finish and impact protection. If you don't laminate it, the wing will be only as strong as the glue that holds it together. Someone on Thingiverse posted a wing printed out of ABS with some steel bars fitted lengthwise for reinforcement but this must be heavy as.

If you're considering making your own wing with help of 3D printer I strongly recommend looking into moulding described by PrfctChaos. 3D printing the mould is much easier than 3D printing the wing itself - for starters, you can print the mould from PLA because the mould strength isn't essential, it just needs to be stiff but doesn't really need any high strength. PLA is very rigid when printed with some reasonable infill and this is enough for good dimensional accuracy of the finished wing. Printing PLA is heaps easier than anything else I know and this is important especially with large prints like hydrofoil wings. I suffered from large warping at the base of my PETG prints which made gluing it together a nightmare. Also finding a glue that will actually stick to plastics like PETG is difficult, nothing holds reliably but I don't know about PC filaments.

I can imagine that printing with PC will pose some other challenges but the point is that you will make your life easier if you just make a mould of cheapest PLA instead of the printed wing of the high-end filament like PC.

Hi,

I'm trying to find the moulding process, where is it?

Thx

viewtopic.php?p=1123960#p1123960

[downunder]

Cool, thanks!

Can I get the Fusion file as well, or that's not available?

Oh, I've been told th Fusion has a wind tunnel option, Chaos are you using that?

[PrfctChaos]

Wind tunnel option in Fusion? No, I don't know about it, I didn't think Fusion does CFD.

Fusion file for? That wing is made a fit a Tarroa Sword 2 Fuse.

[downunder]

Dunno, a mate here was saying it has cfd, maybe not.

It would be relatively easy to change to some other fuse tho. I can try at least...

[Jake_55]

PrfctChaos,

Thanks for the kind words Jake. As always, I'm just keen to see a few more ripping and beautifull custom wings out there. The big brands with their overpriced popout wings are held in too high regard in my books (and have riden plenty of them).

Would be interrested to hear which profile option you are going with. And your planned use for the wing. Are you choosing the low aspect 1200cm shape for waveriding, or another reason? Possibly because the moses 633 has pretty similar dimensions?

Hi,

we've come far enough for me to be able to give a progress update. I was able to design and cnc cut the front wing from foam. After that we laminated the foil in fibreglass unsing vacuum suction aswell - it turned out really good for our first try. See pictures below:

Obviously there is still some sanding and colour needed. We plan on connecting the foil to the fuselage using an 3d printed adapter (see cad).

To answer your questions: I went for the mh23 profile. And I have chosen the dismentions for ease of learning - not high speed. And you are absolutely right with the moses 633 - I'm choosing the dismentions around that foil.

I'm planning on pairing that foil with a 450-483ccm back foil. I'm doing my research on it right now ... I don't know the AR yet and I don't know how important the profile is going to be in the back. So yeah

Still a lot of work to do xD

- Jake

[PrfctChaos]

Thats looking great! How many layers / weight of fibreglass did you go with?

[Jake_55]

Thats looking great! How many layers / weight of fibreglass did you go with?

2 Layers top and bottom in heavy 400g (i think). Seems stiff enough. We did all layers in one go. We have to test it to really see, if it’s stiff enough.

[faklord]

Hi Robke,

I think the below freeride wing looks pretty good. 750 mm wingspan, 750 cm^2 area (It is just a touch larger than the theoretical minimum zone, but going down to 600-675 cm^2 only has a very small advantage). Recommended profile is the S2055. Make it in Polished aluminium would look awesome (would be a bit worried about damaging the thin trailing edge, but would definitely look awesome).

Capture.PNG

Capture2.PNG

Hi PrfctChaos,
I'm really itching to make another wing and I've been searching through existing calculations for some inspiration as to what I actually want and that one above looks promising. All the parameters are essentially valid for my case but I was wondering what would change if we make the wingspan smaller (you mentioned 600-675 cm2 has some advantage)? I think smaller aspect ratio wing could be a bit easier to make, store and transport, also I'm not sure if I'm after a hardcore racing wing yet

Also in another reply, you mentioned calculations for a stab. Are you able to calculate the optimal stab parameters for the above wing?

Nice, a fast freeride wing is awesome fun, good choice.

So for 750 mm wingspan and 750 cm^2 area, the results look like this. s2055 profile wins best general profile (Drag of around 2.5 Kg near middle of the range). And rg14a147 doing a bit better in the top half of the speed range (Best High speed biased selection).

Capture2.PNG

For a smaller wingspan of 700 mm, the optimum shows up at a area of 700 cm^2 for this speed range. s2055 profile wins best general profile (Drag of around 2.6 Kg near middle of the range).

Capture3.PNG

I'm sure both of these will have plenty good mid and top speeds. Can't go wrong with either.

Stab optimisation and matching for a specific front wing......... Hmmm..... It is possible, but the main problem is that there are too many extra measurements and info needed. For example, you would need to calculated / estimate the total drag being created by the front wing, mast, fuse and stab itself with the fuse length and front wing centre of lift over the speed range. Just to calculate how much unbalanced moment is left that the rider needs to take of. To optimise, one would then need to minimise the drag and unbalance moment for all the different possible stab profiles as well as a range of adjustment angles for the stab as well as front wings. I'm putting it in the too hard basket for now.

However, I can tell you that my current favourite stab is a fast little stab, that has a wingspan of 390 mm, Max chord of 50 mm and uses a NACA0008 profile. I find it to be really low drag and fun compared to many commercial stabs. Well balanced at a downward angle of 2.5 degrees on my fast surf wing. For your smaller wing you might want to start at about 2 degrees if I had to guess.

Capture5.PNG

Fuse looks interesting..care to share?

[PrfctChaos]

Hi PrfctChaos,
I'm really itching to make another wing and I've been searching through existing calculations for some inspiration as to what I actually want and that one above looks promising. All the parameters are essentially valid for my case but I was wondering what would change if we make the wingspan smaller (you mentioned 600-675 cm2 has some advantage)? I think smaller aspect ratio wing could be a bit easier to make, store and transport, also I'm not sure if I'm after a hardcore racing wing yet

Also in another reply, you mentioned calculations for a stab. Are you able to calculate the optimal stab parameters for the above wing?

Nice, a fast freeride wing is awesome fun, good choice.

So for 750 mm wingspan and 750 cm^2 area, the results look like this. s2055 profile wins best general profile (Drag of around 2.5 Kg near middle of the range). And rg14a147 doing a bit better in the top half of the speed range (Best High speed biased selection).

Capture2.PNG

For a smaller wingspan of 700 mm, the optimum shows up at a area of 700 cm^2 for this speed range. s2055 profile wins best general profile (Drag of around 2.6 Kg near middle of the range).

Capture3.PNG

I'm sure both of these will have plenty good mid and top speeds. Can't go wrong with either.

Stab optimisation and matching for a specific front wing......... Hmmm..... It is possible, but the main problem is that there are too many extra measurements and info needed. For example, you would need to calculated / estimate the total drag being created by the front wing, mast, fuse and stab itself with the fuse length and front wing centre of lift over the speed range. Just to calculate how much unbalanced moment is left that the rider needs to take of. To optimise, one would then need to minimise the drag and unbalance moment for all the different possible stab profiles as well as a range of adjustment angles for the stab as well as front wings. I'm putting it in the too hard basket for now.

However, I can tell you that my current favourite stab is a fast little stab, that has a wingspan of 390 mm, Max chord of 50 mm and uses a NACA0008 profile. I find it to be really low drag and fun compared to many commercial stabs. Well balanced at a downward angle of 2.5 degrees on my fast surf wing. For your smaller wing you might want to start at about 2 degrees if I had to guess.

Capture5.PNG

Fuse looks interesting..care to share?

It's just Gong 70cm carbon monoblock mast (one piece mast, fuse, baseplate)
https://www.gong-galaxy.com/en/product/ ... t-70-surf/

For the pedestal, that fits on the back of the fuselage. I just machined 2 pieces out of wood. That look like below. Then glued them together. Poured some thickened epoxy on the inside and used to fuselage as a mould. So it has a tight fit. Sanded to preferred shape and coat of epoxy on the outside.

FYI, this gong fuselage drawing (got it from somewhere on this forum) does look to be pretty accurate.

[faklord]

PrfctChaos,

Thanks for the kind words Jake. As always, I'm just keen to see a few more ripping and beautifull custom wings out there. The big brands with their overpriced popout wings are held in too high regard in my books (and have riden plenty of them).

Would be interrested to hear which profile option you are going with. And your planned use for the wing. Are you choosing the low aspect 1200cm shape for waveriding, or another reason? Possibly because the moses 633 has pretty similar dimensions?

Hi,

we've come far enough for me to be able to give a progress update. I was able to design and cnc cut the front wing from foam. After that we laminated the foil in fibreglass unsing vacuum suction aswell - it turned out really good for our first try. See pictures below:

IMG_0020.jpg
IMG_0060.jpg
IMG_0062.jpg
IMG_0094[8193].jpg

Obviously there is still some sanding and colour needed. We plan on connecting the foil to the fuselage using an 3d printed adapter (see cad).

adapter_position.png

To answer your questions: I went for the mh23 profile. And I have chosen the dismentions for ease of learning - not high speed. And you are absolutely right with the moses 633 - I'm choosing the dismentions around that foil.

I'm planning on pairing that foil with a 450-483ccm back foil. I'm doing my research on it right now ... I don't know the AR yet and I don't know how important the profile is going to be in the back. So yeah

Still a lot of work to do xD

- Jake

Hi Jake,
Maybe you know this already? : If the shape of of your 3D printed adapter is realistic, there will be a massive stress concentration in the fuse along the back edge of the adapter and this is already a very high stress area (without the concentration):
Something like fuse front end shown in Fig 2 would be much better that Fig 1

Fig 1

Fig 2