Hi John,

I like using SW so please don't get me wrong if this post takes the wind out of your sails and enthusiasm

, but I feel the necessity to explain the order of magnitude of the problem you're trying to solve.

1. A propeller is a rotating wing with varying airfoil profiles, angles of attack, and airspeed. It is not difficult to model the geometry in SW - I can gladly help you with that. Your much bigger problem is modeling the moving turbulent air around the propeller. For accurate CFD you need many millions of small air particles (mesh elements in CFD) particularly in the close vicinity of the wing leading edge.

2. If I could describe CFD in a single sentence, it is would be a digital algorithm for the inversion of a massive double precision floating point matrix.

3. Turbulent flow is by definition time dependent, meaning that at any given instant those tiny particles of air could be moving in a completely different direction from the previous instant. Accurate CFD would require solving the above matrix inversion repeatedly at very small time increments.

4. You can simplify and speed up the process by making some drastic assumptions, like assuming the flow is fully laminar (no turbulence), or assuming relatively large CFD elements to lower the size of the matrix, etc. These assumptions significantly reduce the accuracy and validity of the CFD analysis.

5. The above applies to a

**static** wing. Now add the fact that you have a

**rotating** wing with another rotating wing following closely in its wake. And then in the turbulent wake of this combination we add a static cowling containing cooling ports and geometrically complicated engine parts.

6. Recently I was faced with a much simpler problem that I was unable to solve: I have a cylindrical chimney throwing out polluting smoke next to an apartment building with an open window. Problem: With the wind blowing at a known speed and direction, how much pollution goes into the window?

7. In the light of the above I think we can understand that even the most powerful pc available is like a drop in a bucket and all the pc performance enhancements will make it like two drops in a bucket.

8. But I have a positive suggestion for getting the feel of what CFD can do for you (I'd appreciate feedback on this): Get some wind-tunnel test data/polars on a known airfoil and run a CFD analysis on a thin 2D slice of this airfoil. See if you get some (or any!) similarity between the analysis and the test data - like best L/D and at what AOT. Try different mesh sizes and localized mesh refinements and measure the solve time. How much memory did it use?

Hope this helps.