After being favorably impressed with the SAFE stabilization in the E-flite Apprentice S and Horizon's Sport Cub S, I decided to add stabilization to my Telemaster 40. I chose the Guardian 2D/3D to do this. By using the Guardian, I was able to add stabilization using my old Spektrum AR7000 receiver. I programmed a Spektrum DX9 to take full advantage of the Guardian. This article is a brief description of what I did.
Installing the Guardian in the Telemaster was easy. The guardian input connections (from the AR7000) are made using a "Receiver Connecting Harness." I connected the guardian outputs to the aileron, rudder, and elevator servos. A 6" extension cable connects the "Ail" output to a y-cable and, finally, to the two aileron servos. Because I used separate servos for the nose wheel and rudder, I used another y-cable on the "Rud" output to tie the two servos together. The image below shows the installation.
Here are the AR7000 channel assignments for the Telemaster/Guardian installation:
I used a 6" extension cable on the gear channel to connect to the flap servos via a y-cable. To power the system, I used a Castle Creations 10A Switching Regulator.
In order to fully implement the Guardian, I decided to use my newly acquired Spektrum DX9. I became familiar with DX9 while programming it for my Apprentice S and Sport Cub S. Both of these use "SAFE" stabilization, including a mode-select switch. I began programming for the Guardian with the mode-select switch. I decided to use the convenient, 3-position D switch. The DX9 makes programming mode selection easy through the "F-Mode Setup" and "Spoken Flight Mode" system setups. I used the F-Mode Setup to select the D switch for the mode switch. I used Spoken Flight Mode to assign a display name and voice message for each switch position:
There is a long list of prerecorded voice messages to choose from. Since there was no "2D Mode" voice message, I used "Beginner." Messages will undoubtedly be added to the list as new DX9 updates become available. The image below shows how the "flight mode" switch was set up.
Most DX9 switch and control assignments are made using "Channel Input Config." "Custom Voice Events" is used to assign voice messages to the switches and controls. For example, I assigned voice messages of "High," "Medium," and "Inhibit" to the R Knob gain control. The R Knob also beeps when in the middle of its range (the "Medium" point); so, it is easy to know what the adjustment is doing. There is a separate DX9 "Throttle Cut" menu item for selecting the throttle cut switch.
Note that there are many other possible choices for the switch and control assignments, including two slider switches on the back of the transmitter.
The Guardian has an LED that indicates the current flight mode. For the 2D mode, the LED blinks; for the 3D mode, the LED is on; and for the off mode, the LED is off. Switching the D switch through its positions and checking for the correct LED indication—as well as the correct DX9 display and voice messages—verifies the switch configuration. If the 2D and 3D modes are reversed, you can use the "Guardian Stabilizer Configuration Dialog," which is part of the downloadable software from Eagle Tree (see the "References" section at the end of this article), to reverse the switches. Using the Guardian software requires a USB connection to your computer. An optional USB cable can be purchased from Eagle Tree when ordering the Guardian. I also have a USB extender that allows me to set the Telemaster on the floor and connect the short Guardian USB cable to the computer. There are many USB-extension solutions on the Web.
With the Telemaster and DX9 powered up and the transmitter bound to the receiver, and after the Guardian has been initialized on a level surface, the Guardian can be tested. When the mode-select switch is in the 2D mode, the Telemaster can be moved off level and you will be able to see the ailerons and elevator move to bring the aircraft back to level—assuming the gain control is not in the "Inhibit" position. As the gain control is moved clockwise, towards "Hi" in my configuration, the corrections will be larger. The 2D mode is similar to the SAFE beginner mode—although the configuration options are much greater with the Guardian.
Moving the mode select switch to "Off" disables stabilization and there will be no control surface movement as the Telemaster is moved.
For my Guardian configuration, the 3D mode acts like this: the guardian will remember and maintain the aircraft attitude when the sticks are released (Heading Hold). This can be tested by moving the aileron stick to the right (as an example) and, while holding the stick, rotate the aircraft to the right. After releasing the stick, the ailerons will move so as to maintain the current bank angle as opposed to returning to level, as in the 2D mode. Aside from using the 3D mode for aerobatics, the mode is particularly useful for takeoffs. For a more thorough understanding of the Guardian and its features, you need to read the manual (see "References"). This article only hints at some of the features and uses.
After I fly the Guardian equipped Telemaster, I will add my flying experiences to this article.
I hope you enjoyed this article.