Helicopter Slung Load Stablization Using a Flight Director

This paper describes the concept and the flight test results of flight director for helicopter with slung load which was developed at DLR (German Aerospace Center). The flight director 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 slung 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. After several test phases in piloted ground based simulation 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-yaw mode. In several flight test trials non-DLR pilots were invited to participate in the evaluation of the flight director for both the stable and marginal stable load.