Chapter 1 : RC Helicopter Nomenclature

The typical parts of a radio controlled helicopter is as follows:

Fig. 1 : Nomenclature of an RC Helicopter

The picture above is a typical RC helicopter with the parts labled. The main rotor blades are used to give the aircraft its ability to fly in the air by rotating it until it reached the desired rpm (revolution per minute) to lift itself away from the ground. The main rotor assembly is composed of see saw ( which holds the flybar), blade holder (which holds the main rotor blades) and the rotor head which is connected to the rotor shaft.( See Fig. 2 & Fig. 3 ). Basically there are two main types of main rotor assembly. The one shown on Fig. 2 is a collective pitch main rotor. It means that the rotor blades has a variable pitch. It ads more efficiency on the rotor blades' lifting capacity and vertical flight control of the pilot. The other is the fixed pitch main rotor. The blades' pitch is fixed and the only vertical flight control is dependent on the blades speed of rotation as well as the engine speed. ( See Fig. 3 )

Fig. 2 : Main Rotor Assembly for a Collective Pitch Main Blades

Fig. 3: Main Rotor Assembly for a Fixed Pitch Main Blades

The canopy serves as a protection to the servos, receiver and gyroscope ( see Fig. 1 ). The chassis holds the engine and muffler, rotor shaft, tail boom, canopy and landing skid or landing gear. The tail boom serves as holder of tail rotor mechanisim, tail fins, stabilizer, tail boom support. It also serves as a housing of the rotatng shaft to turn the tail rotor mechanism which turns the tail rotor blades. The tail rotor is designed to stabilize and control the fuselages' heli in flight. It counteracts the torque generated by the main rotor shaft and engine. Without it, the helicopter will be uncontrollable because the fuselage will spin opposite the main rotors' rotation. It is driven by a rotating shaft from the main rotor gear as you can see in the illustration ( see Fig. 4 ). The landing skid serves as support for the aircraft on landing and to stay upright before take-off. There are other types but for now we will concentrate on the most conventional. The powerplant, mainly composed of the engine, muffler, main and pinion gear,clutch is what makes it fly that drives the main and tail rotors.

Fig. 4: Top View of Tail Rotor Assembly

Now lets look at the radio components of the rc helicopter. The servo mechanisms, batteries and receiver controls the aircraft in flight. The movements of the servo mechanisms comes from the radio transmitter signal which the rc pilot makes by moving the control sticks. The cyclic servo controls the direction of the helicopters' fore and aft, left and right. It's very important while hovering the helicopter to balance the rotor and the whole aircraft in flight. The control is usually on the right transmitter stick when you move it. The throttle servo controls the engine speed or power. The movement of this servo is mixed or syncronized with the other two servo controls, the tail rotor servo and the main rotor blade pitch servo ( see Fig. 5 ). Later you will know the reason why there is a need to mix those servo. Then the gyro which helps to stabilize the fuselage. It is connected to the tail rotor servo which creates a self-correcting effect. Whenever you apply an outside force on the tail rotor, it will react in with an opposite movement which counteracts the force applied. This will be discussed in more detail in succeeding chapters so hang-on.

Fig. 5: Radio Components of a RC Helicopter