The model helicopter is mainly depending on the strength synthesis and the decomposition, and its lifting force is equal to its gravity when the helicopter hovers. When the model helicopter goes forward, the original lifting force is divided into two force components vertical and the level. The horizontal component causes the helicopter to advance and the vertical component keeps the helicopter not to tenesmus, but after the original lifting force are divided, the vertical lift component must be smaller than the gravity, and causes the helicopter to fall down; therefore people must enlarge the vertical lift component. Other motivations like backlash are similar and the only differences are the direction. The tail rotor's function is to counter-balance the main rotor and change the fuselage direction.

How the helicopters divide the vertical lifting force incline into horizontal and the vertical lift component? The entire host cycle plane of rotation inclines its surface, and the original vertical lifting force is divided into horizontal and vertical components. How does the main rotor plane of rotation induce the lift the difference?

Change the rotor angle. Let's take advance as the example, the main rotor changes to 3 and 9 do not have the lifting force differences, and at 3 and 9 the lifting force difference starts to produce. Along with the rotor rotation, the lifting force difference enlarges gradually; the 6 and 12 directions have the biggest lifting force difference and it reduces gradually until 3 and 6 directions, when it becomes zero. Rotate for one cycle, and take 1500 rpm rotational speeds as an example, in one minute the lifting force difference can change 1500 times.

Obviously when the rudder is turned, the main rotor angle of attack is changing. The rudder is turned more; the lifting force difference is also bigger. If you still can not understand, you can take out the helicopter. How the main rotor changes the angle of attack? It is achieved by the complex gearing organization and the gyroscopic effect.
If you understood this truth, you can understand why the model helicopter can do tumbles from left to right or from the front to the back. It is not because of the simple side thrust; it is a torsion created by the main rotor surface's lifting force difference. This torsion enables the helicopter to be able to make 3D tumbling in all directions freely.