Dependence of the Oscillatory Movements of an Unmanned Aerial Vehicle on the Forward Velocity

Abstract

If, during a longitudinal flight with constant forward velocity of an unmanned aerial vehicle (UAV), the automatic flight control system (AFCS) fails and the elevator deflection is not in the safe interval, then the flight becomes oscillatory. In this paper, the dependence of the safe interval, the period of oscillations and the ranges of variations of the pitch rate and of the angle of attack on the variation of the forward velocity are investigated numerically, in the context of a fixed value for the elevator deflection and for certain given initial conditions, by using an Scala-based Akka actor system. It is shown numerically that, for increasing values of the forward velocity, the period of oscillations and the crossection of the safe interval are decreasing. The same descending trend can be observed concerning the dependence of the ranges of the angle of attack and pitch rate, when the forward velocity increases.