Thanx
...It's simple - cut a circle out of transparent foil that has the diameter of the rotating propeller and then scratch it in a circular pattern with sandpaper...
I love the effect that you used on the helicopter. I use that on static display of airplanes mounted on a stand. What I do for each blade lines in it to demonstrate movement cutting a wide piece for propeller, 2, 3, 4, and 5 prop propeller, What Mike did for the helicopter is perfect What I am suggesting is for aircraft propellers.