Empennage

empennage: see airplane.

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empennage [¦am·pə¦näzh]

(aerospace engineering)

The assembly at the rear of an aircraft; it comprises the horizontal and vertical stabilizers. Also known as tail assembly.

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Empennage 

aerodynamic surfaces of an aircraft that provide longitudinal and directional stability of the aircraft and control its flight. The control surfaces are usually located in the tail part of the fuselage, and less frequently in the nose part. The design of the empennage is similar to that of an aircraft wing; its total surface is 0.25–0.50 of the wing surface. The various types of empennage are distinguished by their front view, side view, and plan view (rectangular, tapered, elliptical, and, for highspeed aircraft, swept-back). The front part of the horizontal empennage, which carries the elevators, is called the stabilizer. The front part of the vertical empennage, which carries the rudder, is called the fin vertical stabilizer.

The elevator is moved by the pilot using the control stick (pulling the stick toward the pilot causes the aircraft to climb; pushing the stick away from the pilot causes the aircraft to descend). The rudder is operated by foot pedals (pressure on the right pedal makes the aircraft turn to the right; pressure on the left pedal results in a left turn). The angles of deflection of the elevator and rudder are usually ±25°–30°. To maintain proper longitudinal stability of the aircraft, the stabilizer is usually equipped with trim tabs, which can be operated by the pilot to adjust the angle of attack within a range of +5° to — 15°. The trimming mechanism is sometimes connected to the control stick, thus causing the stabilizer to operate together with the elevator. The elevator and rudder are often omitted entirely, and the horizontal and vertical empennage are of the all-moving type. In addition, transverse stability of the aircraft (normally provided by the ailerons) can be improved by connecting the right and left halves of the horizontal empennage with the aileron control, thus enabling the elevators to deflect in opposite directions (differential control). The same scheme is used in operating the rudders and the elevators of V-shaped empennage.

S. IA. MAKAROV