The pitch of the main rotor blades can be changed to increase/decrease the elevation of the helicopter. This configuration results in quicker response to inputs. Collective inputs use the Left stick on the Tx. (see Fixed Pitch and Tx)
What changes the horizontal movement of the helicopter (roll left, roll right, pitch forward, pitch backward). Cyclic inputs use the Right stick on the Tx. (see Tx)
Rx or Receiver. This is the device that sits in the helicopter and receives the signals from your Tx. It communicates these actions to the other hardware on the helicopter, such as servos or motor speed.
Tx or Transmitter. This is the device you hold in your hands that communicates your intended actions to the helicopter's Rx. You use the Tx to fly your helicopter. (see Rx)