The elevator is the primary flight control that makes the aircraft pitch around the lateral axis; by varying the force generated by the tail surface, it redirects airflow and changes the effective shape of the horizontal stabilizer's airfoil. In doing so, it lets the pilot control the nose position and the wing's angle of attack, enabling the airplane to climb or dive through the lift produced by the wing. Operated from the cockpit via cables, pulleys, and bell cranks, this surface translates the pilot's input into smooth, precise pitching motion.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
What is the primary function of an airplane's elevator?
The elevator's primary purpose is to help the pilot to safely fly the aircraft through climbing, cruising, and descending. It is a primary flight control surface that changes the pitch attitude of aircraft; it makes the aircraft pitch around the lateral axis by adjusting the nose angle relative to the longitudinal axis.
Structurally, the elevator is the small moving section at the rear of the horizontal stabilizer, hinged to the fixed sections of that stabilizer. When the trailing edge moves downward, the camber of the horizontal stabilizer increases, generating extra lift that forces the tail up and the nose down. An upward-deflected elevator reduces tail-down force and lets the nose rise. By varying this force, the pilot controls the position of the nose of the aircraft and thus the overall pitch, keeping the airplane stable and upright in the sky.
I understand that the primary function of an airplane's elevator is pitch regulation. By shifting the horizontal control surface's tilt, the pilot commands the nose to rise or descend. The elevator allows the aircraft to ascend or descend steadily. Mild, restorative motions keep the nose stable and avoid big elevation variances, so the aircraft remains steady even when sudden turbulence occurs.
Jim GoodrichPilot, Airplane Broker and Founder of Tsunami Air
How does an elevator control an airplane?
The elevators, hinged flaps attached to the rear of the horizontal stabilizer, form the pitch channel of the primary control system. When the pilot pushes the stick forward, the control surfaces use electric servo motors to drive the elevators down. This up-elevator position decreases the camber of the elevator and changes the local airflow. As the elevators go down, more lift is generated on the tail. More lift creates less tail-down force, and the nose drops. Conversely, pulling the stick aft raises the elevators, increases tail-down force, and rotates the nose upward. Because the elevator must have sufficient authority to overcome any stabilator or fixed-stabilizer moment, its deflection determines the immediate pitching motion.
If the elevators are off as the plane goes down - whether from failure or autopilot controls disengagement - the surface streamlines with the stabilizer, tail-down force relaxes, and the aircraft tends to nose over further. To prevent this, elevator trim uses a trim tab, an adjustable surface connected to the trailing edge of a larger control surface, to re-set the neutral position so the pilot holds zero stick force.
An elevator's purpose is to modify attitude. This control surface is the main part managing the aircraft's pitch orientation. By altering its position it creates the required lift for ascent. Its command is pivotal during departure and arrival. When I pushed rearward on the steering shaft, the nose of the Cessna rose steadily against the skyline. The whole frame rotated around its point of gravity. Any small input can mess up to stop descent, so control surface requirements are precise and sensitive.
Jim GoodrichPilot, Airplane Broker and Founder of Tsunami Air
What controls the elevator in a plane?
The pilot controls the elevator by moving a small control wheel forward or back inside the cockpit. This input is passed to the elevator by a system of cables or pushrods that run through the fuselage. On fly-by-wire airplanes, servos actuate the elevator in response to the same motion. In a conventional tail the elevator is a hinged surface attached to the trailing edge of the horizontal stabilizer, while in a stabilator design the entire horizontal stabilizer pivots, giving a large, rapid pitching moment. As the elevator tilts down the tail lift rises and the nose pitches up, so the aircraft can climb. When the elevator lifts the tail lift falls and the nose lowers, letting the airplane descend.
In a small aircraft, I control the control surface through the command column and sense the aerodynamic pressures immediately through the related wire connections. When I tug rearward on the yoke, the elevator surfaces move upward,the snout goes up, and the change leads the rear to go down. When I move the yoke ahead, the aircraft descends.
Jim GoodrichPilot, Airplane Broker and Founder of Tsunami Air
How does elevator movement affect an airplane?
Elevator movement changes aircraft pitch attitude by rotating the airplane about its centre of gravity. When the pilot moves the control column aft, both right and left elevators move up together. This increases the camber of the horizontal stabilizer and generates extra downward lift on the tail. The tail rises, the nose sinks relative to the centre of gravity, and the aircraft pitches up. Conversely, forward column movement deflects both elevators down, reducing camber and downward tail lift so the tail drops and the nose pitches down.
Because elevator deflection alters the centre of pressure location on the stabilizer, the pitching moment changes until the centre of pressure again coincides with the centre of gravity in the new attitude. The lift vector, always acting at 90° to the relative airflow, therefore changes orientation. In a climb it no longer points straight up, so the aircraft assumes a different angle of attack and flight-path angle. Back elevator pressure applied during the transition from straight-and-level flight to climb increases load factor, stressing wings and tail, while the phugoid oscillation that follows a sudden pull-up illustrates how the aircraft eventually returns to the angle of attack it was trimmed for.
What are the types of airplane elevators?
Three common elevator configurations are T-tail elevators, stabilators, and canards. Antiservo tabs are incorporated on the trailing edge of stabilators to decrease sensitivity and give the pilot better feel. Trim tabs, balance tabs, antiservo tabs, ground-adjustable tabs, and an adjustable stabilizer are all secondary surfaces that fine-tune pitch control and reduce pilot workload. The type of elevator system an aircraft uses affects stability, efficiency, and safety. Different types of elevators are designed to meet specific aircraft requirements, from small single-engine airplanes to supersonic fighters and transport-category jets.
