alt Hacker NewsI would think so, or by taking cross sections. Its hard to believe they have some miraculous geometry that needs guarding anyway. Maybe they are trying to dissuade people who might try to 3d print an impeller.
3d models for industrial fan manufacturers (Sanyo,NMB) are widely available.
There could be geometrically tiny optimizations that lead to an outsized impact in noise and flow by turbulence reduction. While optimizing an impeller with computational FSI (fluid structure interaction) is not as hard as before, it still is not trivial. And it's these (perhaps small) optimizations that justify Noctua being 5x more expensive than generic black fan.