Conceptual Aircraft Design

6Empennage and Other Planar Surfaces

6.1 Overview

Chapters 4 and 5 dealt with the pertinent aspects regarding the aerodynamic considerations of the wing and fuselage. The wing and body are found to be inherently unstable. Therefore, an empennage is required to balance this combined wing‐body instability as well as offer the requisite control to execute manoeuvres. This chapter is devoted, primarily, to describing the role of empennage, the physics involved, aerodynamic considerations, possible choices and the advantages and disadvantages of the options available. In this book, while the horizontal tail (H‐tail) and the vertical tail (V‐tail) are sized for new aircraft configuration, the control surfaces are not sized. Control surfaces are earmarked into their positions with statistically obtained typical sizes.

This chapter deals also discusses other types of lifting surfaces, for example, ailerons to execute roll control, LERXs (strakes) for additional vortex lift and other planar surfaces, as aircraft components, these are studied at the conceptual stage of a new aircraft design project. These planer surfaces have an aerofoil like cross‐section with chord length many times longer than the thickness. They are meant to generate forces and moments, some as modifiers to improve flow around bodies (e.g. dorsal fins, speed brakes serving as drag generators for deceleration) and others are mere support structures (e.g. a pylon).

This chapter covers the following topics:

• Section 6.2 ...