The radio control (R/C) system is the heart of our hobby. This magic box can turn a lifeless pile of balsa into a graceful soarer, a flashy acrobat or a snarling 150-mph pylon racer. Which radio is right for you? Read on as we lead you through the maze of features and technical jargon that make up the modern R/C system. Once you understand what all those buttons on the transmitter do, it will be easier for you to decide which radio and features meet your needs.
R/C Radio Systems Features
The first thing you need to decide is how much you want your model to do. For each control function, you need one channel of control. The usual uses for control channels are:
Control Channel Usage
* When a powered model does not have a throttle, it flies at full throttle until it runs out of fuel. The model is then glided-in for a landing.
- Control Channel*.....Rudder
- Cars/Boats..............Throttle, steering.
- Control Channels....Rudder or aileron, elevator, throttle.
- Control Channels....Rudder, aileron, elevator, throttle.
- Control Channels....Rudder, aileron, elevator, throttle, flaps or retracts.
- Control Channels....Rudder, aileron, elevator, throttle, flaps or retracts.
When you have more than 6 control channels, you can add such features as bomb drops, dive brakes, parachute drops, sliding canopies or other operating parts to your model. The most common number of control channels used on a powered aircraft model is 4. Sailplanes, cars, and boats usually use 2-3 channels. Four-channel control gives you full acrobatic capability and will enable you to fly most airplane models.
Mode 1 / Mode 2
Refers to the stick configuration of an aircraft transmitter's control sticks. Mode 1 has the aileron/throttle on the right stick and the rudder/elevator on the left. Mode 1 is popular in Europe and Asia. Mode 2 is the USA standard and has the elevator/aileron on the right stick and the rudder/throttle on the left. Almost all radios used in the USA, Canada, Central and South America are Mode 2. All 4-channel and above aircraft radios sold by Tower Hobbies are Mode 2 unless otherwise noted.
AM: Stands for Amplitude Modulation which transmits by a variation in the amplitude of signals, it is subject to interference more than FM.
FM: Stands for Frequency Modulation which transmits signals by variations in frequency, reduces the risk of "glitches" due to signal interference.
PCM: Stands for Pulse Code Modulation uses binary code to digitize the signal, providing the most accurate signal possible.
2.4GHz: Simply by pushing a button, you link the receiver to a single transmitter -- each 2.4GHz FASST transmitter has been assigned a unique ID code at the factory. Once that link is set, the receiver responds only to that one transmitter. In addition, the 2.4GHz systems never stay on a single frequency for more than two milliseconds. You never have to worry about signal conflicts, and never need to wait for an open frequency
A servo contains an electric motor and is the "muscle" that moves the rudder, elevator, or other control surfaces. For each channel of control, you need a servo. Most 4 or more control channel radios come with 2-4 servos. There is a wide variety of servo types depending upon their intended use. If your 4-channel radio only comes with 3 servos and you wish to fly a "full-house" airplane (one that has 4 controllable features) you'll want to purchase one additional servo.
| Servo Shopping Tips
|There are few hard and fast rules fo selecting the perfect servo. However, here are a few points you may want to consider before you buy.
|Analog Servos: Lowest in cost, best for sport.
||Digital Servos: Superior to analogs in speed, precision, smoothness, centering, holding power and dependability Downsides: higher cost, greater energy needs.||Size: How well does it fit? Modifications are possible, but may affect performance.|
|Ball Bearings (BB) Help servos last longer and run smoother and faster than bushing servos||Gears: Molded gears cost less. Metal gears are stronger and more dependable, but may cause interference.||Torque: Read "muscle." Does the servo have the power you need?|
|Brushless Servos: 30% faster than brushed digital servos, with five times more service life.||Programmable/S.Bus Servos: Allows programming of most (or all) parameters for truly custom performance. ||Transit Time: Read "response time." Slower servos are more forgiving; faster servos excel at swift, strong response.|
|Coreless (Motor): Improves resolution for smoother operation (than cored motors).||Weight: Lighter is better. Added weight drains packs faster and can affect balance and handling.
The radio unit in an airplane or vehicle which receives the transmitter signal and relays the control to the servos. This is somewhat similar to the radio you may have in your family automobile, except the radio receiver in the airplane perceives commands from the transmitter, while the radio in your car perceives music from the radio station.
This feature automatically returns a servo or servos to neutral or a preset position in case of a malfunction or interference.
A dual rate switch on the transmitter can reduce the amount of servo travel. This makes the controls less sensitive. The aileron and elevator control channels are the most common channels with this feature, although some radios will also have a rudder dual rate switch. Select low rate, and an over responsive model can be made easier to control. Since beginners tend to over-control the model, low rate can also tame their models.
NiCd (Nickel-Cadmium) Batteries
The most common and economical type of battery. The voltage of a typical NiCd (or NiMH) cell is 1.2V.
NiMH (Nickel-Metal Hydride) Batteries
While about the same size and weight as NiCd cells, NiMH cells offer a wider range of capacities. NiMHs are also more environmentally friendly, requiring neither cycling or recycling.
LiPo (Lithium-Polymer) Batteries
More costly than NiCd or NiMHs, LiPos also offer higher performance due to lighter weight (about half that of NiCds or NiMHs) and higher voltage (3.7V, or 4.2V for balanced cells.)
LiIon (Lithium-Ion) Batteries
Longer than NiCd or NiMH cells, LiIons also cost more and require special chargers. However, cell voltage is 3.6V (vs. 1.2V) and can reach 4.1V in balanced (equalized) cells.
LiFe (Lithium-Ferrite Phosphate) Batteries
New lithium-based LiFe cells are flat and thin like LiPos, but offer less volatility and slightly lower voltage.
Like all radio equipment, an R/C system broadcasts its signal at a specific wave rate and this is known as its "frequency". Just as commercial radio stations that you listen to each operate on their own frequency, so do R/C transmitters. There are several different frequencies to choose from and these are referred to in the R/C industry by "Channel Number". This channel number is easily confused with the number of control channels used in the model but the two are quite different - the channel number that your transmitter broadcasts on (e.g., channel 56 or channel 80) refers to its frequency, not the number of model features it can control. If there was only one R/C frequency or channel number available, only one person in any given area could operate their model - just as if there were only one TV channel, you would only be able to choose one show to watch! By having a number of different channels available, many models can fly, race or skim along the water at the same time. (See Ordering Radios for more information on the available channel numbers.)
2.4GHz Spread Spectrum Technology
One of the most exciting new breakthroughs in hobby radio technology is the use of 2.4GHz spread spectrum technology -- which gives modelers of ALL skill levels the fastest, smoothest, most accurate and most reliable control possible. Futaba's 2.4GHz radio equipment in particular has advantages that greatly benefit new R/Cers. Simply by pushing a button, you link the receiver to a single transmitter -- each 2.4GHz transmitter has been assigned a unique ID code at the factory. Once that link is set, the receiver responds only to that one transmitter. In addition, Futaba 2.4GHz systems never stay on a single frequency for more than two milliseconds. You never have to worry about signal conflicts, and never need to wait for an open frequency when you're eager to enjoy a day of racing or flying with other modelers!
This effective method of training allows two transmitters to be connected by means of a trainer cord. The instructor can pass control over to the student's transmitter so that he can fly. If the student gets into trouble, the instructor can regain control instantly.
This feature allows you to reverse servo rotation. If a channel operates opposite of its intended direction, a simple flick of a switch corrects the problem.
Adjustable Travel Volume(End Point Adjustments)
ATV allows you to preset the maximum travel of a servo to either side from its neutral position. Such settings help tailor control action to suit your flying or driving style.
Exponential Rate(Adjustable Rate Control)
This feature smoothes responses between stick or wheel and the controlling servo movement.
Direct Servo Control(DSC)
This feature permits you to check servo operation without broadcasting a radio signal. A cable connects the transmitter to the receiver. Direct servo control is very useful for on-the-ground control checks.
Two control channels can be coupled together so that they move together when only one control channel is activated. Many 1/4 scale models require a combination of aileron and rudder to turn. Mixing does this electronically at the transmitter. V-tailed models, where the two halves of the V-tail must move not only together but independently, are another use of control mixing.
Programmable or Computer Radios
These high-tech radios are not inexpensive but allow a full set of programmable transmitter features like multiple plane memory, preprogrammed maneuvers (rolls, loops, etc. at the touch of one button) and much more.
Choosing Your First Radio System
Now that you understand what all the features on a modern radio system are, which radio is right for you? The answer depends upon your present use, future use and of course, your budget. Analyze your needs carefully and then select the radio that best meets those needs. Choose the tab above or click the name below for the radio system that best describes your interest.
Air Radio Systems if you want to fly an Airplane, Sailplane or Helicopter.
Surface Radio Systems if you want to run a Car, Truck or Boat.
In addition to the features available in R/C systems, many manufacturers make optional accessories that will expand your capabilities. In the Radio Accessory Category Section you'll find radio accessories broken out by category or in our our Annual Catalog, you will find a list of accessories made by each manufacturer. Because similar accessories by the various manufacturers do similar tasks, Tower Hobbies has defined some of the more complex items:
Battery Eliminator Circuitry (BEC): A circuit that eliminates the need for a receiver battery, usually in R/C cars.
Electronic Speed Control: Electronic speed controls replace the mechanical speed control and servo providing enhanced power efficiency and precision. In addition, they are lighter which improves the performance of some electric models.
Servo Arms: Connect the servo to either a pushrod or cable. Adjustable servo arms are available for some radios which can be made shorter or longer.
Frequency Checker: A device that automatically scans R/C frequencies and identifies which ones are currently in use.
Frequency Modules: A frequency module plugs into the transmitter and enables you to change the channel number your radio broadcasts on. Some new frequency modules also allow you to now dial in the frequency virtually eliminating the frustration of not being able to fly if someone else is also on your frequency.
Servo Gear Sets: Servo gears can be damaged in a crash and the loss of just a few teeth can render the servo useless. A replacement gear set lets you fix the servo yourself. It's very handy to have extra gear sets!
Servo Case Sets: A cracked or broken servo case can let dirt, water or fuel into the sensitive electronics of the servo.
Servo Connectors/Adapters: Most manufacturers offer servo plugs that are compatible with their radio systems. This allows you to adapt other brands of servos to your radio system or repair damaged plugs.
Servo Extension Cable: (Aileron Extension): These cables simply increase the distance between a servo and the receiver. Note: Very long servo leads may cause radio interference. Chokes or radio noise traps may be required.
Y-Harness: Two servos can be plugged into one channel with a Y-harness. The two servos will then operate simultaneously. It is most often used in areas where the strength of one servo is not adequate.
Servo Trays: Servos can be mounted in a tray which provides for easy installation and good vibration protection. Many different styles are available to fit various installations. If all your models are outfitted for the same servo tray, transferring components between models is easy.
Trainer Cord: Required to connect the two transmitters with trainer systems. Note: Be sure to check your instructions for proper connection and for compatibility with other radio systems.
Tower Hobbies is the Choice!
Click here to go to our Frequency Channel Chart
More modelers buy their radio systems and accessories from Tower Hobbies than any other supplier in the world. We have the largest selection, best service and super-low prices. When you do decide which system is for you, order it from Tower Hobbies! If you still feel unsure about whether you've chosen the correct item, just give us a call at 1-800-637-6050 and our friendly phone representatives will answer your questions and help you place your order.