The main thing to remember about frequencies is that only one person can transmit on a certain frequency at one time. Before turning on your transmitter at the flying field, it is your responsibility to make certain that no one else is operating on the same frequency! FREQUENCIES FOR NON-FLYING MODELS: Apart from the above listed model aircraft frequencies in the 72 MHz band, the FCC has allocated 30 frequencies in the 75 MHz band for the exclusive use of R/C'ers who build model cars, boats, or any other type of non-flying "surface" vehicle. The FCC differentiates between "aircraft" and "surface" models because of the potential for radio interference between the two distinct classes of R/C models. For instance, an R/C car being operated in someone's driveway could cause an R/C airplane being flown several miles away, out of the car driver's sight, to fly out of control and injure someone, if they were on the same frequency. To avoid possible interference of this kind, "aircraft" and "surface" models are required by law to operate on entirely different frequencies. It is very important that you are aware of this difference and always use an approved frequency in all of your R/C models. It is dangerous, as well as against the law, to use an aircraft radio in a surface model, and vice versa!

One of these emblems should appear on the box of all new radio systems. They were developed to help dealers and their customers quickly identify whether the radio is on a frequency intended for aircraft or for surface vehicles.

CHANNEL NUMBERS VS. NUMBER OF CHANNELS
The channel number assigned to the frequency shouldn't be confused with the number of "channels", or controls, that your radio can operate on the model. It takes a separate channel to operate each one of the model's controls! For instance, an R/C model that has the same 4 primary controls that a real airplane has would need a 4-channel radio system - one channel to operate the ailerons, one to operate the elevator, one to operate the rudder, and one to operate the throttle. On the other hand, some R/C models, such as the famous SIG KADET SENIOR, are specially designed to fly with only three-channel control (rudder, elevator, and throttle). Also, many R/C sailplanes fly beautifully on only two channels (rudder and elevator). Highly advanced R/C scale models will often use the 4 primary channels plus a 5th, 6th, or 7th channel to operate such features as retractable landing gear, flaps, bomb drops, etc.
Generally the channels available on a model airplane radio are utilized as follows:

We recommend that your first radio be a 4-channel system! If you are like most people starting in the hobby, you will eventually want to fly models with complete 4-channel controls, even if your trainer only needs 3 channels. With a 4-channel radio you will have the capability to move on to more advanced models after you've learned to fly. You can always use 2 or 3 of the channels to fly simple models, and still have the additional channels available when you want to fly a full-house airplane. In the long run it will be cheaper to buy a 4-channel radio right at the start than to get a 2 or 3-channel radio and then try to sell it later when you want to upgrade to a 4-channel model. Not only that, but most 2 - 3 channel radios come with dry-cell (throw-away) batteries, while 4-channel radios normally have rechargeable nicads. That alone is usually worth the difference in price between a 2 - 3 channel radio system and a 4-channel radio system.

The Sig Riser 100 is a simple-to-build and easy-to-fly sport sailplane that is happiest when gently floating in the lift of passing thermals. Like most gliders, the Riser 100 uses two channels to control the rudder and elevator. An optional third channel may be added to operate spoilers on the top of the wing.

OPERATING THE TRANSMITTER
Model aircraft transmitters have become fairly standardized over the years in the layout of the control sticks on the front of the box. It wasn't always that way. In the early days of R/C, many different stick arrangements were tried in an effort to make it easier to fly R/C. Today there are basically three transmitter stick arrangements in use around the world. For a typical 4-channel model airplane, here is how they work:

Mode-II is by far the most popular method in the United States! This grouping of the ailerons and elevator on the right stick very closely duplicates the control stick arrangement in a full-size airplane. Consequently, most people feel Mode-II is a more natural way to fly R/C than either of the other modes. The vast majority of the R/C fliers in the U.S. fly Mode-II, and we advise you to learn that way. All of the radios you look at in the hobby shop will undoubtably be Mode-II, the other types must be special ordered.

The Sig Kadet Senior and its smaller sister ship, the Kadet Seniorita, are considered by many experts to be the best R/C trainers on the market. They each were designed to use three channels (rudder, elevator, and throttle).