He had taped a string in front of the windshield to determine his rudder trim input.
If the rudder input produces a coordinated turn, the ball will remain centered during a roll maneuver.
The first officer attempted to keep the plane upright with aggressive rudder inputs.
This was due to the ability of a yawl to be trimmed to sail without rudder input.
When rudder input was made, the two surfaces on one side opened, top and bottom, creating drag, and yawing the aircraft.
It has some adverse yaw, and therefore requires rudder input during turns.
At takeoff, a canard pusher pilot does not have to apply rudder input to balance this moment.
However, the captain failed to use any rudder inputs at all, before or after disconnecting the autopilot.
He hated the idea of taking off with rudder input, but he was afraid of losing control around the turn.
There is hardly any yaw, and without the rudder input the slip ball barely moved half its width.