As Tommy mentions, there's quite a few "non-dimensionalized" coefficients and numbers related to aeodynamics, and indeed most scientfic areas of interest where things can be quantified.
Many of them have little application to practical model flight. About the only one which gets attention is the Reynolds number, which is in essence a "scale factor" which can be used to predict wing performance.
It's based on airspeed and the wing chord, and experience with wind tunnel experiments and models place lower limits on what is a "good" value for it on a model, and what might be poor.
Model aerodynamics deal with very small numbers relative to full-scale, and good reliable research in the field is rare. But for most of our model stuff it's been found that for an RN (also seen as Re) below 100,000, flight performance may be poor unless pains have been taken to design the wing for the low-speed, small chords which this value represents.
For example in the Canard thread, it's noted that small chords work poorly... extending the chord is the same as increasing the RN for the surface.
Dr. Mark Drela has done extensive research into the low-speed area of model flight and has developed a series of airfoils more suitable than the typical fat curved surface seen most often on slow flying or small models.
Aerodynamics is a complex science with many factors influencing all the other factors, and it's difficult to pick it up by merely listening to what often times is ignorant speculation.
A good library is a must if you want to get more into design than merely TLAR, just to seperate the baloney from reality.