Observe the behavior of the glider while in straight flight. Look for indications on the turn coordinator that indicate yaw to one side or another when no control inputs are being made. Make sure to do this in an area with little wind.
Determine whether an adjustment to the left or right is necessary. If the ball on the turn coordinator is right of center, this indicates that right correct is needed. If the ball on the turn coordinator is left of center, this indicates that left correction is needed. If the ball is centered with no rudder inputs, then no offset adjustment is necessary.
Observe how much rudder input it takes to center the ball on the turn coordinator. If possible, have your passenger look toward the rear of the glider while corrective input is established. Make a mental note of how far off the rudder was deflected to maintain a centered turn coordinator.
Locate the rudder trim tab on the trailing edge of the rudder at the rear of the aircraft. It is often a flexible piece of metal on the bottom of the rudder.
Observe whether there has been any previous correction made to the rudder trim tab. From this, you can determine whether more correction is needed in the same direction as previously adjusted or whether it should be returned to center.
Adjust the trim tab in the required direction. Do this using your hands and gently bending the tab without making a crease in the metal. After this is finished, you can fly the glider again to determine whether the offset update was successful.
