What is the angle of incidence?
The model rc planes is great when flying in the air, particularly a scale warbird model plane. Trainer plane is more relax in comparison to a previous mentioned one but, to keep both plane flying level at high speed it needs some technique called Angle of Incidence. This angle is not only keeping the model in the air with more lift but also maintain a good level flight at travelling speed. Normally the angle of incidence is positive when using Datum Line (longitudinal axis line) as a reference.
The RTF (Ready to Fly) model rc plane always has this angle applied from the factory. But to many builders the correct Angle of Incidence only obtains throughout several flight test. Owing to my experience some RTF plane still need significant modification on this issue for its error in level flying. The strange behavior happens from its tendency to over nose up when the engine speed increases but the pitch (elevator) is not applied.
The value of the Angle of Incidence is variable upon the wing type which can be justified as follows.
High wing trainer and Shoulder wing trainer with Flat Bottom Airfoil need Incidence angle set up with two positive degrees. On the same type of High wing trainer but with Semi-Symmetrical Airfoil need three to four positive degrees.
In the Aerobatic model rc plane that has Shoulder or Low wing with Symmetrical Airfoil need no more that one positive degree Incidence Angle.