Drag considerations for flight in atmospheric turbulence

Abstract

The distribution of lift between the wing and tail surfaces of a conventional aircraft is examined in order to determine the combination that would produce the minimum drag for a given lift. Further, the center of gravity (CG) position which gives the desired lift distribution and at the same time, maintains aircraft trim is determined. Furthermore, a classic set of non-linear equations of motion for longitudinal flight is reduced to a set of linear equations by linearization. The location of the CG of the aircraft is then changed and a linear feedback control law is used to retain the dynamic characteristic (flying qualities) of the airplane. The response of the aircraft to an external disturbance such as a gust (modeled with a stochastic process) is studied in terms of drag versus CG position. Finally, it is shown that the position of the CG for minimum drag should be determined with consideration of the expected atmospheric turbulence.