My favorite way to portray an inflight model was what I like to call the old "Pat Hawkey" method.
Some of you old timers may remember Pat from his features in Fine Scale Modeler back in the 80's and 90's.
He was well known for his presentation desktop models, built on contract. Most of those that I recall were jets of one kind or another, but he did prop jobs too.
His method of portraying a spinning prop was very unusual - he simply left it off.
He would fill and smooth the spinner or hub and simply attach it sans blades, celluloid discs, fancy photo-etch 'whizzy fixies,' etc.
His theory was that the only truly realistic spinning prop was, well... a spinning prop. Anything else looked too contrived and actually took away from the desired effect. He left it to the mind's eye to make the connection of a an inflite prop and the clean effect he achieved actually worked pretty well.
Here's an example of his work...
And heres a bio piece on Pat with link to him ...
http://www.milartgl.com/models/models.htm