Introduction for the remote:

A radio-controlled model (or RC model) is a model that is steerable with the use of radio control. All types of vehicles imaginable have had RC systems installed in them, including cars, boats, planes, and even helicopters and scale railway locomotives.

History

Radio control has been around since the late 1800s with Nikola Tesla having demonstrated a remote control boat in 1893. The World War II era saw increased development in radio control technology. The Luftwaffe used controllable winged bombs for targeting Allied ships. During the 1950s pioneering work was done by enthusiastic amateurs to create valve based control units. Originally simple 'on-off' systems these evolved to use complex systems of relays to control speed and direction. The information was encoded by varying the signals mark/space ratio (pulse proportional). Rapidly commercial versions of these systems became available. The tuned reed system brought new sophistication, using metal reed switches to resonate with the transmitted signal and operate one of a number of different relays. In the 1960s the availability of transistor based equipment led to the rapid development of fully proportional servo-based systems, again driven largely by amateurs but resulting in commercial products. In the 1980s, integrated circuits made the electronics cheap, small and light enough for multi-channel fully proportional control to become widely available.

In the 1990s miniaturised equipment became widely available, allowing radio control of the smallest models, and by the 2000s radio control was commonplace even for the control of inexpensive toys. At the same time the ingenuity of modellers has been sustained and the achievements of amateur modelers using the latest technology has extended to such subjects as gas-turbine powered aircraft, aerobatic helicopters and submarines, to name but a few examples.

Before the days of radio control many models would use simple burning fuses or clockwork mechanisms to control flight or sailing times. Sometimes clockwork controllers would also control and vary direction or behaviour. Other methods included tethering to a central point (popular for cars and hydroplanes), round the pole control for electric model aircraft and control line (USA: u-control for internal combustion powered aircraft.

Radio-controlled cars use a common set of components for their control and operation. All cars require a transmitter, which has the joysticks for control, or in pistol grip form, a trigger for throttle and a wheel for turning, and a receiver which sits inside the car. The receiver changes the radio signal broadcast from the transmitter into suitable electrical control signals for the other components of the control system. Most radio systems utilize amplitude modulation for the radio signal and encode the control positions with pulse width modulation. Upgraded radio systems are available that use the more robust frequency modulation and pulse code modulation. The radio is wired up to either electronic speed controls or servomechanisms (shortened to "servo" in common usage) which perform actions such as throttle control, braking, steering, and on some cars, engaging either forward or reverse gears. Electronic speed controls and servos are commanded by the receiver through pulse width modulation; pulse duration sets either the amount of current that an electronic speed control allows to flow into the electric motor or sets the angle of the servo. On the models the servo is attached to at least the steering mechanism; rotation of the servo is mechanically changed into a force which steers the wheels on the model, generally through adjustable turnbuckle linkages. Servo savers are integrated into all steering linkages and some nitro throttle linkages. A servo saver is a flexible link between the servo and its linkage that protects the servo's internal gears from damage during impacts or stress.


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