Smooth looking loop

Hello everyone i’m Jorge aka xBLues. I’m glad to be able to participate in the forums. Well, I want to make a movie clip for a rotating fan with 4 blades and then have it looping in the main document. I tried to do a movie clip for the first 90 degree rotation and i expected it to loop and look like a fan that is rotating continuosly. However, after the 90 degree animation ends and before it starts again, there is a delay so the clip doesn’t look like a rotating fan. I mean, it rotates 90 degrees, it stops, it rotates another 90 degrees, it stops and so on. Does someone know how to make this kind of movie clip? I have made the clip using the Macromedia Flash Tutorial (the one that comes with the Macromedia Flash software) but maybe i’m missing something. Do i have to use Action Script for this?
Well i hope that wasn’t too long. I would apreciate any help or sugestion.