Dynamic stability of a hose-drogue-wing system for aerial refueling

Abstract

In this work the classical hose-drogue system has been modified by adding a small lifting surface at the end of the hose and just before the drogue. This small wing can help to stabilize the static position of the system as well as to improve the dynamic characteristic of the hose-drogue. The hose is assumed to behave like a cable with tension and no bending forces are considered at the present time. Assuming that the dynamic effects are small compared to the static effects, a linearized expression for the perturbed motion of the hose in the vertical plane and the incremental hose tension are obtained. The resulting equations are linear with variable coefficients that depend on the static equilibrium position and static tension of the hose. The wing at the end of the hose generates unsteady aerodynamic forces that depend on the vertical velocity of the hose at the end position and of the unsteady angle. These forces are taking into account by means of the simplified model of Theodorsen¿s theory. The assumption of exponential dependence with time of the dynamic variables is made, and the resulting equations are solved by means of a finite element method. The system is thus transformed to an eigenvalue problem to obtain the natural frequencies and damping coefficients. The influence on the dynamic characteristics of the different parameters of the system is presented.