Why use motion blur? It can be slow, and unruly to work with at times. If you can get away without motion blur, but still have the blur effect, that would be ideal.
Create the illusion of a fast rotating propellor with nothing more then a few gradients in C4D
CyBear has been posting some great tips for Cinema 4D over the last little while. Here, he shows how you tax gradients in C4D to create the effect of a fast spinning propeller blades. This can be the same effects seen in an aircraft, or a fan.
Using gradients in C4D can be a great alternative to using motion blur. Adding a ton of motion blur to a scene can really effect the render times, so faking an effect like this can be much more efficient.
As CyBear noted, this wouldn’t be a great technique to use for something that was physically close to the camera. Mid to far staged elements though can really benefit from using gradients in C4D rather than motion blur when rendering.