Info About Radio Equipment

RADIO EQUIPMENT

The radio that controls the model airplanes consists of several components. The basic idea is that of a radio station emitting signals and a radio receiving signals on different channels. The Pilot holds a radio transmitter, this emits the signals and there is a receiver which is put into the airplane, that receives the signals emitted by the transmitter. This off course is done controlled by different frequencies. The transmitter and receiver has to be of same frequency in order to be capable of sending and receiving signals. There are special devices called SERVOS attached to the receiver which convert the signals into a mechanical force which drives a horn attached to it, hence moving the control surfaces of the aircraft. All these components are powered by special batteries call Nicad Batteries. These are rechargeable. All of these components are discussed in more detail in the following paragraphs. Transmitter

The transmitter is a box held by the pilot with different switches and levers that control the different functions of the aircraft. A channel is required to control each of the functions. Rudder, Elevator, Aileron and Throttle are the most basic channels required to fly an airplane and do most maneuvers, although you can also fly with only Rudder and Elevator. So the more channels you have on your radio, the more functions you can control. Most of the transmitters have two main sticks at the front. The right stick controls the Ailerons and Elevator, and the left one controls Throttle and Rudder. These are the four most commonly used. The other functions are normally in the form of levers at the top of the radio or switches. Other channels are used for controlling landing gears, dropping bombs, towing up or getting towed up etc. A transmitter normally emits a signal of approximately 1 Watt which is quiet sufficient for taking the plane upto most peoples' vision capacity. Receiver

A receiver is a small and light weight equipment put into the aircraft. It receives the signals transmitted from the radio transmitter. It has connection points for Plugging in Servos and the battery that powers it. The transmitter only receives the signals from the same frequency transmitter and of same modulation type. Switch Harness

This little switch is installed on the airplane, at a place where it is accessible from the outside. It has normally three leads, one goes to the battery pack, the other one goes into the receiver and the third one is used to connect the charger to charge the battery pack. This is used to turn the supply of power on and off to the receiver. (The transmitter's power on/off button is on the transmitter itself.) Modulation

The radios come with three types of Modulation, i.e. AM, FM and PCM. The AM (Amplitude Modulation) is less expensive and is susceptible to interference from other sources like power lines, lightening etc. Not many radios are being produced with this type these days. The FM (Frequency Modulation) is better than the AM, has almost zero interference problems, bit more expensive than AM. This is the most commonly used type these days. The next type is PCM (Pulse Code Modulation). It is even more expensive than the FM. It gives you the ability of a fail safe mode when there is a glitch. What that does is moves the servo positions back to the good signal state or you can preprogram to go back to whatever position you want to avoid or minimize the crash damage. It may or may not be beneficial all the times. If the last good signal was when you were doing a loop, it is not good to have the servos locked in that position. However it is entirely at each person's point of view which one is better or not. Remember that most of the people fly on FM. Servos

The servos are very small motor driven devices. They convert the radio signals into a physical movement. They have output shafts to which an arm or wheel is attached. When the receiver gets the signal from the transmitter to move the output shaft rotates which in turn causes the arm to swing in the direction asked by the transmitter. Onto those arms a push rod is attached the other end of which is connected to the function we need to operate like throttle, aileron etc. One servo is required for each function or channel. So you need as many servos as many functions you want to control. The servos come in different sizes and weights. Small planes have less room, so small servos are used, if the plane is big enough, you can put standard servos. The smaller the servo gets, the price goes up. Batteries

In model plane flying, we use Nickel Cadmium NiCad batteries to power the electronics. The transmitters normally operate on 8 cell packs. The receiver battery is normally comprised of 4 cells. These batteries can be recharged 1000s of time and are more reliable than the ordinary batteries. They range from 50 - 1500 mAh and above. The higher the amperage rating, the longer the batteries last before you have to recharge them. To see a picture of each of the radio component, click here