Also, when the flaps are lowered, it effectively gives the wing some "washout" which makes the wing a lot less likely to tip stall during the landing approach, a good thing for a scale warbird with a high wing loading. Super clean planes like sailplanes are almost impossible to spot land without flaps or spoilers to put the "brakes" on during a landing approach. They just float and float and float as you rapidly run out of runway to land on. Most RC planes are aerodynamically dirty enough that they don't need flaps.

Heavy and clean planes need flaps.
Light and dirty planes don't.