There are several ways to do this. This example is a quick (1 hour) demo of one way to do it, based on the method used by some flight simulators.
The basic principal is this:
1) Multiple copies of the prop are created, each more transparent than the last (I used 4, you could use more if preferred). As the prop spins up each copy lags a bit, so the faster the prop spins the more 'separated' the copies become. This simulates how the human eye tracks fast moving objects.
2) At a certain point, the prop copies are replaced by a disc that rotates backwards and forwards, simulating a stroboscopic effect. Replacement in this case is done by switching the visibility of the prop copies off in the same frame that the disc's visibility is switched on.
I spent no time creating a proper bump map for the spinning disc and just used the prop texture. The effect would be enhanced with a fine radial bump so the specular response is greatest at two opposite sides, depending on available lighting.
For some reason I'm not able to upload the .an8 file for you to pick apart. Also, apologies to any aeroplane enthusiasts for the awful prop modelling :p
