science

The forces on a blade of this size are truly staggering, when you think about how long a lever they are attached to only one side, its clear that the issue is not only strength at the seam of a proposed joint but also the impact any additional weight will have on the junction of the blade with the rotor. They are pushing the limits of what high pressure molded composites can handle at these scales, but still some companies have developed multi-piece turbine blades.

Generally the biggest downsides to multi-component blade technologies are that they cost substantially more, and they have lower operating lifespan, a bad double whammy for the profitability of a windmill.

Basically the cargo plain developers are banking on the cost per flight of each turbine blade being less than the cost of building, installing, maintaining, and replacing multi-part blades over the lifetime of the windmill, and as of now this economics pencils out. Who knows though, tech changes fast, what I wonder is whether portable blade foundries might not be possible to build the blades on-site for large windmill projects.

If you want to get into the nitty gritty I found this presentation very helpful: https://windmillstech.com/wind-turbine-design/

we already know how to build bigger planes. the lockheed CL-1201 design study is from like the 60s.