Fixed Ducted fan

[Dren]

Hello All,

this maybe a daft question, but here it is...

Instead of rotating a fan inside a duct, would it be possible to fix a thin duct to the blades so it also rotates?

The would enable there to be a lot of blades in a small space, and without tip vortexes it should be a lot quieter. I appreciate the extra mass would be harder to change fan speed, but with modern materials that is feasible and the support on the tip would make it stronger. Could it have, say, 16 blades?

I'd be interested in your opinion of this idea.

All the best

Dren