When is the elevator trim control wheel rotated for nose down trim?

The elevator trim control wheel is used to adjust the neutral position of the elevator, thus allowing the pilot to maintain a desired pitch attitude with less control input. When the trim wheel is rotated forward, it effectively causes the elevator to move downward. This downward adjustment of the elevator pushes the tail of the aircraft upward, which results in a nose-down attitude for the airplane.

Understanding the operation of the trim wheel is crucial for managing the aircraft's pitch without constant control pressure. In most aircraft designs, moving the trim wheel forward helps stabilize the nose down attitude, allowing for a more comfortable flight experience and reducing pilot workload. The concept is rooted in the aerodynamic principles that dictate how control surfaces operate in conjunction with the forces acting on the aircraft during flight.