Maneuvering Heavy Sling Loads Near Hover Part I: Damping the Pendulous Motion

In Part I of this paper the dynamic system of a` helicopter with a sling load is analyzed in a fundamental way, using approximate models. The approach considers the three most significant degrees of freedom: translation and attitude of the helicopter and the displacement of the load with respect to the helicopter. After a simple transformation of variables, the translational motion of the center of gravity of the combined helicopter‐load system is used instead of the translation of the helicopter. With large pitch damping, the translational motion is only weakly coupled to the attitude and load motions, leading to a straightforward analysis of the alternatives for damping the “pendulous” mode of motion. In Part II “minimal excitation” of the pendulous motion is pursued for three distinct maneuvers: acceleration‐deceleration, changing the hover location and arresting a pendulous load motion. Ideal thrust angle input functions are determined which in the absence of disturbances result in no pendulous motion at the end of the required maneuver.