Active aerodynamic stabilization of a helicopter/sling-load system

Abstract

A general theoretical model is used in order to investigate the possibility of an active aerodynamic stabilization of a helicopter/sling-load system in the case of a single suspension point. The stabilization system includes two vertical aerodynamic surfaces that are located on the external sling load. The incidence angles of these surfaces are varied according to a set of control laws. This study leads to a system that is relatively easy to realize. The input measurements of the load stabilization system (LSS) include the helicopter and sling load lateral/directional angular rates. It is shown that adding a feedback loop that is based on the load lateral acceleration increases further the stability of the whole system. Studies also show that a single rear surface is very efficient and can be used alone. The proposed LSS is capable of stabilizing the system in a wide range of airspeeds, load weights, suspension methods (geometries), and aerodynamic properties of the external sling load.