Yeah.... typically, barn door relates to the size and shape of the ailerons. They are usually formed by building them, sort of like wing sections, but smaller. The strip ailerons consist of a single (on each side) strip of aileron shaped balsa that is in one piece and runs pretty much the entire length of one side of the wing (and of course, the other) as shown in the diagram LNEWQBAN posted.

We often refer to "barn door" as large sized control surfaces... not only for the ailerons, but for the rudder and elevator as well.


CGr.