22.14. 55 Empennage/Stabilizers

Reference:  Abbott, Richard. Analysis and Design of Composite and Metallic Flight Vehicle Structures 3 Edition, 2019

The empennage of an aircraft is also known as the tail section. Most empennage designs consist of a tail cone, fixed aerodynamic surfaces or stabilizers, and movable aerodynamic surfaces.

The tail cone serves to close and streamline the aft end of most fuselages. The cone is made up of structural members like those of the fuselage; however, tail cones are usually of lighter construction since they transfer less load than the fuselage.

Figure 22.12.2‑1 Typical Metal Tailcone Construction  (FAA-H-8083-31, 2012)

The other components of the typical empennage are of heavier construction than the tail cone. These members include fixed surfaces that help stabilize the aircraft and movable surfaces that help to direct an aircraft during flight. The fixed surfaces are the horizontal stabilizer and vertical stabilizer. The movable surfaces are usually a rudder located at the aft edge of the vertical stabilizer and an elevator located at the aft edge the horizontal stabilizer.

Figure 22.12.2‑2: Components of a Typical Empennage  (FAA-H-8083-31, 2012)

The structure of the stabilizers is very similar to that which is used in wing construction. Figure 22.12.2‑3 shows a typical vertical stabilizer. Notice the use of spars, ribs, stringers, and skin like those found in a wing. They perform the same functions shaping and supporting the stabilizer and transferring loads. Bending, torsion, and shear created by air loads in flight pass from one structural member to another. A horizontal stabilizer is built the same way.

Figure 22.12.2‑3: Vertical Stabilizer and Rudder Construction  (FAA-H-8083-31, 2012)

Where composite sub-assemblies with cored skin are used the structure becomes simpler with fewer parts required. The skin requires less intermediate support from ribs and there is a minimum of internal components required for structural integrity.

Figure 22.12.2‑4: Internal Structure of a General Aviation wComposite Horizontal Stabilizer (Author’s Collection – Courtesy of Stratos Aircraft)

The rudder and elevator are flight control surfaces that are also part of the empennage.