A TIME-VECTOR ANALYSIS OF THE FREE LATERAL OSCILLATION OF AN AIRPLANE

of Master of Science. This thesis presents a time-vector method for extracting the lateral stability derivatives of an airplane from its fixed-control, lateral oscilla-tion. The method of analysis is based on the concepts of rotating vectors long used in the field of electrical engineering. Specifically, the relation-ships existing between the phases and the amplitudes of the multiple degrees of freedom, and their time derivatives and integrals, of a linearly oscillating system are time-invariant. That principle permits a com-plete analysis with the oscillation "frozen " at any chosen time. ' The time-vector method of analysis can be applied to either the direct or the indirect stability problem. 1. It can be used to determine the phase and amplitude relationships between the multiple degrees of freedom of a lightly-damped, oscillating system when the sta-bility derivatives are known. 2. It can be used to determine the stability derivatives of a lightly-damped, linearly oscillating system from transient flight records. This report is concerned with the second application. The method is developed and then applied to the lateral oscillation of a fighter air-plane. A number of advantages which are a result of the physical insight afforded by the graphical solution are enumerated