The electrostatic pinwheel is an experiment where a wheel with radially aligned spikes is turning like they were jets and matter was being pushed out of the ends. It works by charging the surrounding air (corona discharge) with the same charges and then repelling from the like-charged air cloud (which is also getting blown in the opposite direction).
As far as I understand, negatively charged pinwheel throws out some electrons (photoelectric effect) making the nearby air negative. Positively charged spikes ionize the surrounding air and pull in some electrons making the air negative. However, both of these charging mechanism seem to rely on air being there to be repelled from.
Would this device turn in vacuum? The spikes would still have greater electric field than the rest of the surface. It might make electrons be thrown out. Does it mean it could turn as a jet accelerating electrons and slightly getting accelerated by electrons? Or is the mass of electron too tiny to give noticable momentum and overcome any realistic friction?
And what about the positive case? Could it work as a ion jet? It should probably mean a higher threshold and more work on exiting material, but as a result the electric field would be higher and exiting charge would be heavier - maybe that's even better for a jet engine?