How To/Basic Radio Programming

FLY BETTER WITH PROPER CONTROL SETUP

Fly better with proper control setup

With today’s computer radio systems, RC pilots have a tremendous amount of functionality at their disposal. Often however, newcomers to the hobby can find it difficult to program their new computer radios. Understanding the basics of programming and setting up the radios correctly are the keys to maximizing your model’s potential and performance. This article shows the basics of programming your radio so that you can avoid some the common pitfalls that can trip you up. For this article, we’re using the Tactic TTX660 transmitter, but the procedures are basically the same for most radio brands. Some of the terminology may be slightly different but the functions and mixes will accomplish the same result: making your airplane easier to fly. Let’s get started.

A great way to get acquainted with new radio systems is to go online and check out the radios with the features you like that are in your price range. Many, if not all, radios will have downloadable operation manuals, and so that’s a good place to begin.

A FRESH START

Many programming problems are caused when a modeler uses a leftover program memory from an older aircraft that is no longer used. It can be frustrating when your radio does unexpected things when you try to set up your new model. Always start with a fresh program model in the computer radio’s memory. Also, be sure to read your radio’s instructions as the various buttons needed to enter the program menus can vary from brand to brand. Typically, there are three ways to use these buttons: Hold down the enter button and then switch on the radio, switch on the radio and then press and hold the enter button, or simply press the enter button after the radio has been switched on. All are easy to do if you read the manual.

Access the system setup menu. Here, you can enter your username; make sure you are set up for mode 2 (throttle and rudder functions assigned to the left stick with elevator and aileron functions on the right stick). Next, go to the model setup menu so that you can begin a new model memory. Now go to model select. Here, you’ll find submenus for model management, wing type, channel assignment, warnings, etc. Go through the list of model memories and select a new, unused memory from which to start. Actually, it is a good idea to periodically go into your memory list and reset unused memories back to the factory default by using the “clear” function. From there, you can rename the memory and know that you are starting without carrying over any weird unknown settings. With the Tactic TTX660, you can store the setting for up to 30 models.

MODEL TYPE

With the Tactic TTX660, you have a choice of airplane-, helicopter-, or drone-type programming. Other radios may have type choices like glider or sailplane as well. You don’t want to select “helicopter” programming when you try to set up your fixed-wing model. Get into the habit early of checking the model-type menu before you enter the function menus. Whenever you select the model type, you are selecting the specified functions for that particular aircraft.

PROPER NAMES

With a fresh model memory to customize, give it a name to avoid future confusion. Depending in the number of characters to which you are limited, name your model memory so that it is easy to identify. If you have two or more similar models, add extra info to the name, something like Piper1 and Piper2. You get the idea.

WING TYPE

Now go to the Wing Type screen. Once you enter this function, you’ll have a few choices for both wing and tail setups. With the TTX660, the choices are simplified, including Flap Settings and

Tail Settings. In the Flap section, you can chose 1AI, for a wing with one servo controlling the two ailerons, 1AI1FL for ailerons and flaps controlled with one servo each, 2AI for ailerons controlled with two servos, and 2AI1FL for dual aileron servos and an single flap servo. Under the Tail section, the choices include Normal, V-tail, Delta (or elevon), and 2Elev for dual elevator servos. Of course, other brands have slightly different menu choices, but the choices listed here cover your typical airplane types and setups.

SERVO SETUP

Once you have your system set, you move onto the various servos in your model and their functions. The servo submenus will typically be separate from the system menus, and with the Tactic TTX660, you find them in the Settings menu. From there, you enter the Servo Set menu, where you can adjust settings for Servo Reverse, Subtrim, and Travel. All of these are used to get your model set up with the proper control responses. With the Servo Reverse menu, you simply choose Nor (normal) or Rev (reverse). This is so that, when you move the stick for up or left, the servos move in the correct directions.

TRAVEL

To control the servo’s travel (controlsurface throw), you can increase or decrease the travel percentage. You usually want both halves of a self-centering control stick (both the up and down) movements to be equal. But for noncentering controls, like the throttle, gear switch, and flap positions, you will need to fine-tune the travel settings so that you get the proper amount of travel at each extreme travel point. You can do this by moving the control stick so that that portion of the travel percentage is adjusted. This helps avoid overdriving your servos, causing controllinkage binding, especially when you have some channel mixing dialed in.

SUBTRIM

Subtrim is similar to the travel adjustment except that it adjusts the center point of the servos when at rest. It is important, however, to first try to center all your control setups mechanically. Set up your servo arms so that they are fully 90 degrees to the control’s pushrod, and make sure that the control horns are directly aligned with the control hinge lines. After you get the geometry as close as possible, use the subtrims to precisely dial in the control-surface neutral positions. A large amount of subtrim adjustment is not advisable as it can affect the control’s overall servo travel and endpoints.

DUAL RATES AND EXPONENTIAL

These functions are perhaps the most important when fine-tuning your model’s response and performance. The setting can vary

somewhat depending on how you like to set up your aircraft. Find a comfortable control setup by test flying your model. Some pilots prefer little or no exponential, while others prefer large amounts. The same is true for the percentage of control throws for each of the high- and low-rate settings. A good way to sort out your settings is to adjust them in small increments and then test-fly the model. Find a high dual-rate setting that offers maximum maneuverability without breaking (high-speed stalling) out of maneuvers at full power, and a low-rate setting that lessens pitch-control sensitivity to make flights smooth and landings comfortable without running out of up-elevator during flare. Exponential control makes the control response softer around the center neutral position and is often referred to as “feeling like a car’s power steering.”

AILERON DIFFERENTIAL

This function causes the ailerons to move more in one direction than in the other (more up-travel than down). This is commonly used with scale models and some scale aerobatic planes to minimize unwanted adverse yaw. Aerobatic pilots use it to set up a nearly axial roll response. Scale pilots use it to avoid unwanted skidding during turns. To test an aerobatic plane for adverse yaw, enter a vertical downline from a safe altitude and hold full aileron without adding any elevator input. With the throttle set at idle, see how the model responds.

If its nose veers off the downline, some aileron differential is required. Most models will benefit with a little more up-aileron travel than down. Remember, aileron differential is only available in the wing-type selection that has two servos (one for each aileron). With the TTX660, that would be 2AI and 2AI1FL.

USEFUL MIXES

Once you have your model dialed in for smooth and consistent control responses, you can start to dial in mixes to help eliminate or minimize unwanted traits. You can mix in a little rudder deflection when ailerons are applied as another way to deal with adverse yaw. Also for more advanced maneuvers, like knife-edge flight or point rolls, you can adjust for unwanted pitch or roll coupling when large amounts of rudder are applied. If, when you roll into the knife-edge position (wings vertical) and apply rudder to keep the nose from dropping, the nose veers toward or away from the landing gear, that is known as pitch coupling. If the wings try to roll out of the knife-edge position with rudder input, it is considered roll coupling. A small amount of corrective rudder-to-aileron or rudder-to-elevator mixing can make a big difference and greatly lessen the load on the pilot.

When it comes to adjusting the throttle linkage and response, throttle curve is an excellent way to fine-tune the travel endpoints as well as the overall throttle transition relative to your stick position. Flap-to-elevator mixing is also helpful. When you lower the flaps and your model pitches nose-up or nose-down, this mix can make the transition from up flaps to down smooth and easier to control. Other flap mixes can be used for flaperon control with funfly aerobatic airplanes. This is where aileron and flap functions are combined and often also mixed with opposite elevator control throw (flaps downelevator up) for extreme aerobatic maneuvering. These functions can also be assigned to a switch so that the condition can be switched on and off.

SWITCHES

If you look at any computer transmitter, you’ll see lots of switches, knobs, and buttons. These are all used for nonprimary control functions. The primary functions of throttle, rudder, aileron, and elevator control are all assigned to the two main control sticks. The most common uses of the switches are for selecting high and low rates, activating auxiliary channels for retractable landing gear and flaps. They also have specific functions such as for Trainer mode and for activating mixes. With many radios, you can select whatever function you like and assign it to a switch of your choice.

BOTTOM LINE

Depending on the brand of radio you are using, these basic functions will go a long way in making your model easier to control, which will allow you to concentrate on flying your model instead of trying to correct for unwanted conditions. You’ll fly better, and your model will perform more smoothly. Always check your radio system’s instruction manual to understand its programming basics.

Unwanted coupling of pitch and/or roll when rudder is applied can also be corrected by using mixes.

It is important to select the model type and match it to the aircraft you are setting up. Various functions are activated when you select the model type. Highlight the model from the list, and press the Enter button.

The Model Select screen shows your list of model memories. Once you select the model you want, you can go on to the Settings screen and access the servofunction choices.

Once the preliminary function choices have been selected, you go to the Servo Set menu so that you can adjust the functions of your servos.

The Model Setup screen brings up the submenus relative to model adjustment and functions.

Once you properly adjust your radio’s programming, you will fly better and your airplane will respond more smoothly, lessening your piloting workload.

Programmable radios, like the Tactic TTX660 shown here, provide modelers with a lot of flexibility. Although the names of the features may vary, all radios use the same basic menus and submenus to access the various functions. Note: Shown here is the...

Flap mixing allows you to add elevator trim (or correction) when the flaps are lowered. This helps eliminate any nose-up or nose-down pitch changes caused by deploying the flaps.