"My perspective is from using the polar images from the airfoils................."
You asked if there are any thoughts on that idea. My thought is, as Silver Lotus said, that the published data on these airfoils is not particularly representative of the real world for our model size wings. As a matter of fact, the polars can be wildly inaccurate.
To help understand the effect of Reynolds number, a simple analogy may be helpful. Consider a wing the size of the Spruce Goose. Imagine that it had that same 2415 airfoil that you mentioned. What would be the radius of curvature of the upper surface of the wing ? Huge is the word that comes to mind. Now, take that same airfoil and build a wing with a 6" chord. What would be the radius of curvature of the upper surface now ? So the question is: how well does the airflow follow the curve of the Spruce Goose airfoil versus the 6" wing, in spite of them being the same airfoil ? It's a sure thing that the air will flow much further along the upper surface of the Spruce Goose wing before separation (think: stall) as compared to the little 6" wing.
This analogy is not entirely accurate, but it helps to grasp the effect of size on any given airfoil. Unfortunately for us, most wind tunnel testing is done to predict the performance of large airfoils, not small ones.
Dick
Last edited by otrcman; 12-10-2016 at 03:30 PM.
Reason: spelling