Step 11 says to carve the trailing edge block to match the curve of the sheeting and suggested doing it with an X-Acto #26 whittling blade. I didn't have an X-Acto #26 whittling blade so I used a razor plane, then sanded to shape.

The next step is to cut out a space for the aileron servo.
This plane comes with a one piece full length aileron but I will be modifying it for flaps because I want to experiment with taking off and landing with flaps. Does anyone know how much length should be used? Is there a calculation to figure this or is it just a percentage of the overall length of the surface? For example, for a control surface that is the width of the wing, should 70% be for flaps and 30% for aileron, etc.?

That's all for the right wing, on to the left...