Kitesurf Hydrofoil Front Wing (aerofoil, lofting, wing, mirror)

[Anonymous]

Advice please. I am attempting to 3D print a kitesurf hyrofoil front wing. Some links for the curious:

https://www.google.com/search?q=kitesurf+hydrofoil&safe=strict&source=lnms&tbm=isch&sa=X&ved=0ahUKEw...

https://www.seabreeze.com.au/forums/Kitesurfing/Foiling/3d-printing-hydrofoils?page=1

I have printed a back wing using SketchUp and it worked fine. The wing was printed, then I layered carbon fibre with epoxy over it, sanded it smooth and drilled some holes. This worked very well.

Things I don't know how to do:

1. Placement of aerofoils (want constant 3 degrees angle of attack at all points of wing, want 19mm profile thickness at centre)

2. How to make the gull wing shape: https://waveandwake.com/hover-glide-space-skate-foil-wing ... how do you curve the wing and keep the thickness correct?

3. How to get a wing of area 900 cm sq? (see hover glide wing shape as 'inspiration')

4. The wing will attach to my hydrofoil with 4 bolts, so it needs a flat area in the centre of the wing (https://www.kitesurfshop24.com/media/image/product/3757/lg/zeeko-hydrofoil-alloy-bullet-2019~14.jpg) that has curves at the front and back

5. Once the wing is designed I will want to sprinkle some 'pits' over the surfaces, and holes from top to bottom to allow the epoxy to flow in and strengthen the wing. It would be nice if I could place these using some sort of pattern (e.g. every 10mm in a hex pattern)

When the carbon fibre and epoxy are applied to the wing, a sheet of peel ply is placed over the wet mixture, then paper towels and then a layer of plastic sheet. This is then covered with 10cm of soft foam and a sheet of plywood. The entire thing is then compressed, the foam presses the plastic / paper towels / peel ply ... I am doing a terrible job of describing this:

https://s3.amazonaws.com/cdn.fibreglast.com/images/vacuumbagging_diagram_WEB.jpg

I don't use a vacuum, the foam compression is good enough. I noticed that for the wing I have already made, this compression changed the shape of the wing. I ended up building a lego scaffolding to hold the shape while it was under compression.

So after that long boring reason, I would also like:

6. A scaffold for the bottom of the wing to support it under compression so it doesn't change shape. The scaffold should be such that the wing doesn't shift.

Could anyone help with advice on any of the above. Sorry for the huge list, but I guess it's better to have the whole story, not just random bits.

Many thanks,

[davebYYPCU]

I will go point by point but some things overlap.  How?  Fusion has many ways to skin a cat, so these suggestions can be accomplished in user preferred methods.

1.  Keep the datum line of the airfoil on the Origin plane and add 3 degrees to the mounting section only.  Add 19mm dimension, as required.

2. Top view and front view curves, in separate sketches, then a 3d sketch to find the intersection curve/s.  Where leading edge and trailing edge curves are joined, they should be separate sketches.  Loft is finicky about this type of construction.  Thickness curves used as rails.  Disclaimer as above.

3. Ball park, or exact?  When the topview is drawn, Fusion will give you the area of that profile.

so bit limited to 2d calcs unless you want to go through some more detailed steps.

4. Second body shaped as desired, and combined to the wing, but that base line includes the 3 degrees Angle of Attack.

5.  Pits - not sure about that, got a better description?, Holes in a pattern is easy enough, make one, rectangular pattern in model space, and suppress the ones too close to the Boundary involved.  

6.  3d print a mold off the wing, to sit the bottom lay up on, then the wing, then top layup, compress.

Do half and mirror for the other side.

Attach the file with airfoil and selected front and top views, that example picture has four shapes, which one, they are all doable.

Happy to help....

[Beyondforce]

Hey @Anonymous ,

I have created a series of video on how to design an airplane in F360. In the videos, you will find techniques that should answer some of your questions:

https://www.youtube.com/watch?v=Va39Zlrm4EU&list=PLjGKAi--ZCoZntY2C0JwUjp-FZvqQUgOl&index=4

Cheers / Ben

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[Anonymous]

I've got my outline as a sketch and my profile as a sketch. How do I resize my profile so it matches the outline?

Once I have the width correct, how do I make the profile height 19mm? There isn't a single vertical line to measure, I need to measure the bounding box height.

Thanks for the help, really appreciate it!!

[davebYYPCU]

I am not on the same page, - there are a few ways to measure the 19mm.

if you are sticking to a known airfoil shape, then the 19mm thickness will equal a set and known chord length. 

If you don't need THAT airfoil, make your own, with a rectangle bounding box, which is what I am thinking you are saying.  Rectangle is chord length by 19mm high, making the trailing edge and leading edge, horizontally apart, the top and bottom lines are adjustable for best / better shaping, and would work if measuring the internal vertical line.

After the airfoil is settled and aligned to the origin, you project the LE and TE points to the top view sketch, and complete the top view sketch snapping to those points, this way changing the airfoil chord changes the top view automatically.

Might help....

[Anonymous]

I'm being really thick. How did you make that surrounding box? I figured it out: https://www.youtube.com/watch?v=T1a9iEDWdzY

Like you said, I would like the profile to be 19mm at the widest wing point, then as the profile moves towards the wings it scales the depth with the chord.

I just took a look at the ? labelled part of your diagram .... now you've got me thinking.... I don't know which part should be 19mm ..... hmmmm lol!!

Thanks for the help, appreciate it!!

J

[davebYYPCU]

You didn’t say, if you need to use your airfoil, or a known airfoil, or we can make our own, steps would be different for yours against mine.

Can you attach your file with a reply, will guide you through with it.

[Anonymous]

OMG thank you for all this help, if I could reach through my screen and give you a hug, I would!

I'm using Eppler 817 ( http://airfoiltools.com/airfoil/details?airfoil=e817-il ) at 3 degrees positive AoA. I attempted to import the SVG but I didn't get it right, so I drew around it.

This is at 3 deg AoA. I can't resize it using the construction lines, so those are not connected properly

Top view of the wing, I'm not 100% sure it is the correct size. It should have an area of 950 square cm, don't know how to do this.

The centre profile should be 19mm depth, length is ? Not sure. Don't know how to measure it.

This is the front shape:

The width of this should match the top view. Not sure how to do that either.

This is what I'm kinda trying to make:

I flippin love learning 3D stuff, it's so far out of my comfort zone, it's bonkers how other peoples brains work. They look at all this and understand it. amazing!

[davebYYPCU]

Ok, had a fiddle with your pics.

for a rib thickness, 19mm, the chord line is 173.691 mm, and the top view wing area for that set of sizes, is 584 sq cms.

Something has to give, to get to 950 sq cm.  Let me know.

File attached,