A propeller does two jobs in a soundtrack: it tells you what kind of vehicle is moving, and it tells you how close it is. A small drone whir versus a heavy aircraft engine versus a desk fan are all the same physical principle, but the spectrum is completely different. Mix the wrong one in and the visual stops working.
You will find 17 propeller clip on this page, from full aviation engines and drone hovers to a fan blade buzz and the lighter spin of a propeller hat for cartoon scenes. Aviation videos, game flight sequences, and dieselpunk ambience cuts pull from this folder regularly. Free MP3 download, no signup, no attribution required.