Introduction To R.C. Systems

The following is courtesy of "East Coast Modeling Center."

The radio system is your link between you and your model. They may seem complicated at first but with a little study, all aspects of the radio system can be easily understood. We will attempt to introduce you to the radio system here and explain a few of the features found on many of the systems available today.

Radios are separated into two groups, those used for model aircraft and those used for surface models. Although the operation, electronics, and mechanics for both types of systems are virtually identical, they operate on different sets of frequencies. The separation is stipulated by law and it is to protect the safety of the modeller and those in the vicinity. A flying aircraft can be dangerous if it becomes uncontrolled and the frequency separation helps avoid an aircraft being interfered with by someone operating a car or boat.

In addition to a difference in frequencies, some surface radios are also available with a pistol grip control which is ergonomically easier when controlling cars and boats. A pistol grip for aircraft would be impractical.

The first criteria one usually looks for when choosing a radio is the number of control functions or channels. (Note that the term channels here refers to the number of controls and does not have anything to do with the frequency on which the radio operates.) Generally modern radio systems are available with anything from 2 to 10 channels.

Surface Radios

Radios used for surface models generally have from 2 to 4 channels with 2 channel units being the most popular. One channel would be for the steering of the model while the other would be for control of the speed and direction (forward or reverse) of the model. Pistol grip radios are quite often more comfortable in controlling surface models.

Glider Radios

Gliders usually require 2 channels of control, one for rudder and one for elevator. Additional channels may be utilized for ailerons, flaps, spoilers, etc. on more sophisticated models.

Aircraft Radios

Model aircraft may require anything from 2 to 8 or even 10 channels of control, depending on complexity. The average aircraft will generally require at least 4 channels of control, one for rudder, one for elevator, one for ailerons and one for throttle. Simpler models may omit the ailerons and some even the throttle (common with smaller 1/2A models). With no throttle in an aircraft, the model would be flown with full throttle until the fuel has run out. It would then be glided in for a landing without power. Additional radio channels may be used for things such as retractable landing gear, operating flaps, bomb drop, camera actuation, glider release, etc.

Helictoper Radios

Model helicopters usually require different radios than model aircraft. Their controls are different with more mixing functions required. Usually a helicopter will operate with a minimum of 5 channels with the throttle and collective pitch channels both being controlled by one movement of the throttle control stick.

What Comes With Your Radio System?

Generally you will get just about everything you need when you purchase your radio system. Most aircraft and helicopter systems (of four or more channels) come with transmitter, receiver, three or more servos, rechargeable NiCad batteries for both the transmitter and reciever, battery charger, switch harness, servo trays, aileron extension, frequency flag and extra servo control arms. Surface radio systems do not usually come with batteries or charger and only have two servos.

Transmitter - The transmitter is the control box which you hold that converts your human control movements into electrical impulses and sends them via radio waves to the receiver in your model.

Receiver - The receiver is the small electronic unit in your model which converts the radio signal from your transmitter into electrical control signals which can be sent to your servos.

Servos - Servos are the devices in the model which actually produce the control movements. They convert the electrical signals from your receiver into physical movement to control your model. A different servo is required for each control function or radio channel.

Batteries - Two and three channel radio systems, for the most part, do not come with batteries and additional Alkaline (AA-type) cells are required. Again, these systems are generally used in surface vehicles. Virtually all 4 channel and greater systems come complete with NiCad rechargeable battery packs (for both transmitter and receiver) and charger.

Types of Radio Modulation - When shopping for a radio, you will find that people refer to different types of modulation. They are referring to the way the electronic control information is sent from your transmitter to the receiver over radio waves.

AM - AM, or Ampilitude Modulation, was the primary means of modulation in R/C until recently. The control information is transmitted by varying the amplitude of the signal.