The trimmable horizontal stabilizer (THS) is a key component of modern aircraft tail design, responsible for maintaining longitudinal stability and enabling precise control of the aircraft’s pitch. Unlike fixed stabilizers, a trimmable stabilizer can change its angle of incidence relative to the fuselage. This adjustability allows it to balance the aerodynamic forces acting on the aircraft, reduce pilot workload, and improve efficiency during different phases of flight. Purpose of a Horizontal Stabilizer The horizontal stabilizer is located at the tail of the aircraft and serves as a balancing surface to counteract the nose-down pitching moment generated by the wings and engines. Its primary functions are: Maintaining longitudinal stability. Assisting in pitch control when combined with the elevator. Providing trim adjustments to minimize continuous control input by the pilot. Trimmable vs. Non-Trimmable Stabilizers Fixed Horizontal Stabilizer with Elevator Trim Tabs: In smaller aircra...