RANDOM PROCESS THEORY
There are important problems in flight dynamics that involve the response of systems to random inputs. Examples are the motion of an airplane in
atmospheric turbulence, aeroelastic buffeting of the tail when it is in the wing wake, and the response of an automatically controlled vehicle to random noise in the command signal. The method of describing these random functions is the heart of the engineering problem, and determines which features of the input and the response are singled out for attention. The treatment of such functions is the subject matter of generalized harmonic analysis. It is not our intention to present a rigorous treatment of this involved subject here. However, a few of the more important aspects are discussed, with emphasis on the physical interpretation.