Definition of waiver. 1  1 : the act of intentionally relinquishing or abandoning a known right, claim, or privilege; also : the legal instrument evidencing such an act.
Roll, pitch and yaw. Roll, pitch and yaw are rotations along the natural axes of the helicopter (or any aircraft). A rolling movement is where the helicopter rotates along a line along its length using lateral cyclic inputs (aileron), eventually turning from right way up to inverted while maintaining the helicopter's heading.
Every model has a trim function. On the T638 helicopter, it has 2 buttons in the middle of the remote. For the U820 2.4GHz mini helicopter, the buttons are on the front portion on the top left and right of the remote. For the T655, there is one button below the right hand stick on the controller.