Drag if empty space between motor and propeller

EFOIL.builders Propulsion System (Motor, Gears)
1

Hello, I have a 63100 motor with custom shaft (like 65161 flipsky shaft), on which I put a folding propeller from EML Store. Does the empty space between the propeller and the motor generates a significant drag that should be corrected with a 3D part ?

PXL_20230205_161912689
PXL_20230205_1619126891920×1440 181 KB

This setup is for a foil drive assist,

Thanks,

Nicolas

2

Yes you would be better off filling that space up with a spacer that tapers down to your propeller

3

I’d probably print something to go there, no idea of the efficiency gains but I’m sure there would be some. Let us know if you test it!