This is a video from The Action Lab where they've set up a vacuum chamber with a fan inside along with a number of tiny Styrofoam balls to see if the fan is capable of blowing the balls around after the air is pumped out of the chamber. Well, can it? SPOILER: Only if you turn the fan up past 11 since there's still a tiny amount of air in the chamber on account of it not being a perfect vacuum like my roommate. So yeah, if your spaceship design relies heavily on a fan for propulsion it may be time to head back to the drawing board and hopefully draw something impressive enough for your mom to hang on the fridge because you belong at home.
Keep going for the video, but the fun bit starts around 1:50.
Thanks to Eric L, for reminding me "build a vacuum chamber" was on my list of things to do during quarantine before I used it to dispose of a piece of gum that had lost its taste.