Regarding the comment - "On models ,wing loading and power loading is everything - shape of the airfoil really means little except in very high speed situations. " I agree for the most part. I will make an analogy with my favorite of all subjects: food! Wing loading and power loading are to powered aircraft what the flour, eggs, and sugar are to a cake; the airfoil is to powered aircraft what icing is to that same cake. Without proper selection of wing loading and power loading, you have little hope of meeting your design goals. The airfoil adds that last let's say 10% of some performance measure (I just made that up, clearly it depends on the details of the design and the parameter in question).

An interesting contrast exists however with sailplanes. Sailplanes are typically task oriented designs, and power loading has no meaning for obvious reasons. In the case of sailplanes, the wing loading defines the basic performance of the ship. However, the airfoil selection for sailplanes becomes much more important than for the powered counterparts. This is true for several reasons: the first is Reynolds number, which generally speaking are very small on typical sailplanes, and the second is the optimization of the ratio of lift to drag at some design flight condition, as sailplanes are truly about efficiency.

A great place to start in your pursuit of understanding appropriate wing loading for your application is to compare the wing loading of an existing design which you know to be of roughly the same size and performance as the model you are working with. For instance, if you are looking at trainers, there are at least 20 great designs out there for which data is readily available. Gather information on weight and wing area, and do the calculation.

Cheers.