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Hi,
I am goiing to make a 3D printed + laminated wing to update my LF Rocket foil.
I was wondering if it would be possible to make a fuselage with a carbon fiber tube filling with resin the areas where the mast and wings are attached.
Any thoughts?

I built a complete fuselage using this technic in 2008 using 25mm carbon tube and it worked well. It was light and stiff. Modern foils though now have much thinner fuselages, not sure a 15 or 20mm hollow carbon tube will be stiff enough. Let us know!

I was thinking about 25-30mm diameter. Coming from the LF aluminum fuselage anything will be a huge weight improvement. I don't need to go ultralight and compromise stiffness.
I see there is also solid carbon rods. Maybe the rod is also a good solution. Even if it is heavier than the tube I won't have to fill with resin and should be lighter than aluminium.
¿Is it possible to make threads for wings attachment in a solid carbon rod?

You are absolutely right that LF alum fuse is engineered sloppily. Their carbon offering is somewhat better, but still north of 500 grams is too much. I made 2 fuselages from old carbon naish kite bars - 360 and 370 grams:
For wing attachments you need stainless inserts.

There is other option that I explored before: taking a circular saw and cutting off the excess aluminium where the strength is less critical. This is much quicker 1 day long project, reducing the weight from 1200 to something like 800 grams. Here is the second fuse "blank" with lines marked for the cut off Again, alum fuselage would never be weight-competitive with carbon, this is why I abandoned this project.

Wow, never seen the LF foil before, compared to other foils on the market looks like a Liquid Farce

Thank you for the tips. Do you just epoxy those stainless inserts in the carbon tube?

Seal the insert opening with wax. Drill the hole in the fuse. If the insert fits tight, then just epoxying it inside the fuse hole is OK. If it spins, wrap some carbon cloth around the insert. Use the hammer to knock it deep into the hole.

I use carbon tubes, and they work well. So far I've gotten them mostly from old, broken windsurfing booms. I can use epoxy filler with microbaloons for a lighter fuselage than aluminum or solid carbon, but I use a lot of aluminum plates, too, to reinforce screw points and as screw inserts. I also cover with at least a couple more layers of carbon cloth. It comes in woven sleeves which work great for wrapping a rod shaped object.

https://www.ebay.com/itm/Carbon-Fiber-C ... :rk:2:pf:0

I've built a couple of fuselages with carbon tubes that I made. If it's thinner wall tubing you can add extra wraps in higher stress areas. Also, you don't need to fill the whole thing with filler. Slide in some tight fitting foam plugs and just fill the parts where the mast bonds in or where the wing mounts. Mine ended up water tight and more buoyant with sealed air chambers. With a mast and wings with corecell core the board usually floats on its side after a crash.

If you want to recess in where wings mount, you can cut a notch into the tube, fill with corecell and wrap with more carbon around the reshaped tube section.

Peter