The equations of motion for an aircraft can be linearized about a reference condition within the assumptions of small disturbances and linear aerodynamics. The resulting system of equations is typically solved to obtain the eigenvalues and eigenvectors that describe the small disturbance motion of the aircraft. Results from such an analysis are often used to predict the rigid-body dynamic modes of the aircraft and associated handling qualities. This process is typically carried out in dimensional form in most text books, or in nondimensional form using dimensionless parameters rooted in aerodynamic theory. Here we apply Buckingham’s Pi theorem to obtain nondimensional parameters based on the aircraft rigid-body dynamics rather than aerodynamics. This approach may be more useful for understanding how aircraft dynamics scale with appropriate design parameters
