What are the functions of the horizontal tail?

The horizontal tail provides: Longitudinal stability - Creates restoring moment when aircraft is disturbed from trim (negative lift coefficient slope); Trim - Generates force to balance aircraft about CG for various flight conditions (speed, flap, CG position); Control - Elevator deflection controls pitch rate and flight path angle; Load alleviation - Can reduce wing loads during gusts and maneuvers. Design parameters: Tail volume coefficient (typical 0.8-1.0), Location (aft, T-tail, canard), and Area sizing based on stability and control requirements. Conventional tail behind wing creates download in cruise (trim drag). T-tail provides cleaner wing wake but requires stronger vertical tail. Canard configuration (tail in front) can improve efficiency but has control challenges. All-moving (stabilator) vs fixed stabilizer with elevator affects control power and complexity.