i haven't read anything conclusive in these posts about those nodules but asked that myself, the remnants of the foam injection process or whatever. But probably just coincidence that they are used in some aircraft, and are also seen here. I have shaved all of them off of the upper wing surfaces and fuselage. Didn't do the undersides because of the concave surface, no tool to do it. and my aero ace biplane flies like a champ! So i say they are probably not necessary.

I bought a C radio aa today, I think it's an orange one. They still aren't easy to find in my area.