TABLE OF CONTENTS Lift, drag, thrust, and weight are the four primary forces acting on an aircraft in flight (refer to Fig. 1.1).
Lift and drag are "aerodynamic forces" arising because of the relative motion between the aircraft and the surrounding air. Thrust is provided by the propulsive system, and the force due to gravity is called "weight."
Ultimately, we want to adequately predict an aircraft's motion. An understanding of lift, drag, and thrust is essential to this end. This chapter provides the basics of lift and drag, while Chapter 2 introduces propulsion. These chapters are not designed to replace an aerodynamics or propulsion course, but do provide a baseline we can build on.
We will begin our discussion with a review of fundamental aerodynamic concepts and relationships. A sound understanding of these concepts is necessary to establish a solid foundation for the study of aircraft flight mechanics.
The study of aerodynamics deals with the flow of air. As a body moves through air, or any fluid (liquid or gas) for that matter, the surrounding air is disturbed. The term "flowfield" is common in the language of aerodynamics and is used to refer to the air in the vicinity of the body.
Pressure, density, temperature, and velocity are the key physical properties of aerodynamics. A goal of the aeronautical engineer is to quantify these properties...
