Grok AI helped me design a mast. Is it any good?

In my case the mast sits inside a soft wing sail so section shape doesn't matter.

The mast is a rotating free standing design. First I make L profile corners from a combination of unidirectional and bi directional carbon fiber tape. Then I make tapering side flanges out of aluminium sheet. The pieces are glued with overlap and then the joints covered with bidirectional carbon tape.

Then the aluminium sides and carbon corners are glued together to form a tapered mast. Finally the corner is smooth ed with a filler and covered with bidirectional tape.

Does this make sense or is AI full of it?

 

OK, turns out Grok AI also advises internal bracing like bulkheads and carbon foam panels for the sides. So now the mast construction looks like a very slender foam/carbon sandwich boat hull with solid carbon corners with 80% unidirectional carbon fibers.

Is this a viable way to construct a mast if you are not constrained by aerodynamic requirements or a need for a narrow cross section?

 

The main problem you may have is corrosion. Secondly, What is the advantage to an aluminum extrusion?

 

More then full, it's stupid. Not because a mast couldn't be constructed that way but because it's a waste of materials and introduces problems that can't be managed easily. Corrosion has been mentioned, then there is glueing Al to composites in a structural way. All problems you don't need and simply avoided by using one of the materials alone.

 

Why not ask another branch of AI to critique the design?

 

Aluminium extrusions are not very suitable for unstayed masts since they have no taper. Also they are unobtainium in some parts of the world. Try shipping a 13m mast.

I did go back and forth between grok and deepseek and now have a mast design with spruce cored corners, foam sides in 2 densities, carbon cloth inside and outside with unidirectional fibers concentrated at/near corners and the sides have ±45deg fabric for sheer forces.

Inside the mast are 7 bulkheads

The mast seems strong and light and not impossible to diy. It is made as 4 long L profiles with flanges to glue them together. The glue line is in the middle of the sides where stresses are lowest.

 

You could check aluminum power/light poles; they are tapered. Otherwise, it makes more sense to make it all in aluminum.

 

Why make it complicated? Diy carbon masts have been done before, and it's a relatively straightforward process. The result isn't as light as a professionally buildt mast but that's unavoidable without Al mandrels and autoclaves.
There are two main challenges to overcome when building, keeping the molding surface straight during lamination and releasing the final product. You can do it with some arrangement of two part molding, here's an example, male main mold with separate cap: Mast Building https://teamvmg.weebly.com/mast-building.html The rectangular boom is made in two equal halfs.
Another popular way is with lost foam molds, high density XPS is glued over a rigid core (wood/metal box/pipe) and shaped to the desired profile. The foam is dissolved with acetone afterwards for release. This method gives closed profiles in one shot.

Tapered Al masts can be made from standard round Al pipes of different diameters that are riveted together. The resulting steps are faired over with fiberglass if necessary.

 

Yes i follow this

 

Your approach makes sense. The use of carbon fiber for strength and aluminum for structure is solid. Overlapping the joints with carbon tape adds durability, and smoothing the corners with filler ensures a streamlined finish. Overall, the design should work well for a rotating free-standing mast.

 

How is a rectangular section mast streamlined? Also, the edges of the mast will chafe the sail cloth. Finally, since it is a rotating mast, a square section won't work unless there is some mecanism fitted to it.