TABLE OF CONTENTS To understand how an aircraft behaves, it is essential to develop and understand the aircraft equations of motion (EOM). The EOM consist of the right- hand side of the equations made up of the applied forces and moments, and the left-hand side of the equations providing the aircraft response. The aircraft equations of motion are obtained by applying Newton's 2nd law to a rigid aircraft. Newton's 2nd law states that the summation of the applied forces acting on the aircraft is equal to the time rate of change of linear momentum, and that the summation of the applied moments acting on the aircraft is equal to the time rate of change of angular momentum. To develop these equations of motion, it is necessary to understand the various axis systems. The following section discusses the axis systems used in our development of the EOM.
In this chapter we will concern ourselves with three axis systems. These include the body axis system fixed to the aircraft, the Earth axis system, which we will assume to be an inertial axis system fixed to the Earth, and the stability axis system, which is defined with respect to the relative wind. Each of these systems is useful in that they provide a convenient system for defining a particular vector, such as, the aerodynamic forces, the weight vector, or the thrust vector.
The body axis system is fixed to the aircraft with its origin at the aircraft's center...
