Ah, so nice to come to concensus! The most welcome thing to do, if you can manage, is to define the area of the modellers field, probably it is fenced off? Then tag it with "leisure=pitch" and "sport=model_aerodrome" and optionally a referenced name, and a website for the operating club.

On a sidenote, let me apologise for not answering in your Catala language, I have recently moved from Belgium to Portugal and have my hands and my old mind more than occupied with learning that nice but somewhat queer language. But the Catalan sake has its supporters in Belgium (especially in the North) and be assured am I one!
