How to render rotating propeller? I have a nice (in my opinion :) ) looking propeller on my Fokker VII. I am happy with this for stationary shots, but if I want to composite this in an aerial scene, I obviously shouldn't have the propeller still.



How would you render this propeller in a way that it looks like it is spinning very fast? What are the tricks, do you blur it or something?
I think you mean the motion blur effect.

In Cycles render engine, you can first animate the propeller with a very fast rotation, and toggle Motion Blur in Render tab, then set a appropriate Shutter time:



For Blender Internal render engine, there is also a Sampled Motion Blur panel in the Render tab: 



For compositing, you can enable Vector pass in Render Layers tab, and use Vector Blur node to make use of it. Example: