Interesting concept. On the unconstructibility of efficiently running version, they scaled the 6" model to 3m while holding constant rpm to keep efficiency, an

Interesting concept. On the unconstructibility of efficiently running version, they scaled the 6" model to 3m while holding constant rpm to keep efficiency, and claim it's unconstructible because of tip speed. Shouldn't tip speed be the constant factor? Fluid is entering at and directly interacting with the tip, so I would expect this speed to be matched to the speed/characteristic of the fluid. It may still not be practical, but Mach 11 at the inlet seems totally bogus.