How Radio Controlled Vehicles Work

It doesn’t matter how complicated or simple your model is, the principles are the same. You have a transmitter, which sends a signal to a receiver in the model. This signal is then translated into an action, whether up or down, back or forwards. The system is that simple.

This deceptively simple system allows your model to perform a host of complicated manoeuvres. All under the control of that little box of tricks you hold in your hand. A fine example of this is the radio-controlled helicopter.

A six-channel transmitter controls the standard quality model helicopter. A channel is just an individual route that a command follows. So the receiver on a helicopter controls six different actions.

If you are running an HKH 450 size clone, and depending on the transmitter model you are using, the set up can be as follows. On a Futaba transmitter channel 1 will control the aileron, channel 2 the elevator, and channel 6 the pitch. These channels allow forward, back, up, down and yaw movements.

The tail or rudder is controlled by the fourth channel, which allows movement to the right or left. The last two channels control the gyro (channel 5), and the throttle (channel 3). The throttle is called an ESC (electronic speed control), and must be fitted with a smooth and soft power input into the motor otherwise the helicopter is almost uncontrollable. Almost as importantly, the ESC should let the helicopter motor stop slowly without any braking, otherwise the sudden stopping of the blades can cause havoc to the mechanics.

Apart from the gyro and the ESC, all of these actions take place through servos. These little boxes take the commands from the receiver and translate them back into mechanical actions. The servos push and pull metal links to move the swash plate or tail rotor as commanded.

A servo consists of a small electric motor, connected to a number of gears; these gears allow a micro servo to cope with torque forces of over 1kg/cm. Without this gearing, you would be unable to fight the torque forces generated by a flying radio controlled helicopter and soon crash.

The servos control what is called a CCPM swash plate; this plate translates the transmitter input into very complicated rotor head movements. This gives the radio-controlled helicopter a large range of movements, and the ability to do 3D manoeuvres.

The head hold gyro on your helicopter is a must for proper control. The gyro stops the tail from drifting about either from too much input from the transmitter, or the effect of the wind. If you turn your helicopter left or right without a gyro, the helicopter will want to keep turning, so the gyro picks up on this and corrects the drift.

Like all radio-controlled models, it is the initial setting up which is important, without which you will be unable to properly control the model. The servos must be connected to the correct links, and on a helicopter, the swash must be level, with all movement being equal. The tail should be centred, without any drift, and the pitch of the blades must be level.

Once all the mechanics are as good as you can get them, a good quality transmitter will allow you to make minor adjustments through the transmitter. From the throttle through to the gyro, including all the servos, there is quite a bit of adjustment available via the transmitter. Understanding how the radio controlled model works will allow you to master these adjustments and make your model even more controllable and fun to use.