FLIGHT DIRECTOR FOR HANDLING OF HELICOPTER SLING LOADS

Abstract

This paper describes the analytical investigations which have been performed in preparation for flight testing of a flight director for helicopter with sling load. The flight director developed at DLR gives the pilot a convenient aid to effectively damp the load pendulum motion and to allow manoeuvring without exciting oscillatory load modes. Swinging helicopter external sling loads often lead to dangerous situations which not only can result in a total loss of the transported load itself but also can endanger the safety of the helicopter and its crew. The flight director was flight tested on DLR's BO105 using mainly two different types of external load: a relatively heavy tree log with a basic stable behaviour and a relatively light aerodynamic effective body with only marginal stability properties prone to a coupled lateral pendulum-yaw mode. The analysis base on a non-linear dynamic and aerodynamic load model developed for these investigations.