If you are using the sticks to operate the tank(4 ch), and the Gear Switch for the Main Gun (1 ch), it would seam you only open channel would be your Flaps.

As to the question "why" would you do this - In our battles you get one life, but the Tamiya electronics want to reset themselves. You can stay in one place, but you tank will still visible take hits. This tends to confuse the other drives as to wether you are alive of dead.

With the older Analog radios you could just kill the Tx and the Tamiya electronics would sense the loss of signal and shut down. The Spektrums don't work that way - they maintain constant power to RC gear even when the Tx is off. SD Steve figured out that what the Tamiya system was really looking for was a rudder channel signal. By adding the Pico switch to that servo lead you can use Ch 5 or Ch 6 to turn the servo power on or off, fooling the system into powering the tank on or off