Title: On the Flight Test Campaign of a Coaxial Helicopter for the Development of an Unmanned Aerial System
Abstract: For the development of an unmanned version of an existing helicopter with a maximum takeoff weight of 600 kg and coaxial rotors, a manned flight test campaign is conducted in order to identify the flight physics characteristics of the basis helicopter. Furthermore, the intention of the campaign is to test the future avionics and flight control system which is serving as a measurement system in this campaign. This ensures to incorporate all inherent effects of the avionics system, including sensor dynamics and latencies, for the development of the flight controller of the future unmanned system. Additionally, the flight test campaign is used as a proof of functionality of the avionics system together with the data links under a real physical environment. This paper gives insights into the planning and considerations that went into the flight test campaign. As the identification of the model is performed in the time domain, the focus is set on square wave maneuvers. To identify a set of trim states for the dynamic maneuvers, a simulation study is conducted. At the identified maneuver points, the eigenfrequencies of a linearized flight physics model are calculated to identify the maneuver lengths for the excitation of an appropriate frequency spectrum at the specific flight attitude. To apply maneuvers with the exact length, a way to guide the pilot through the correct maneuver injection via audio input has been developed. This proved to have a significant effect on the maneuver accuracy. Furthermore, a pilot training campaign in a simulator prior to the flight test is carried out and the maneuvers flown by the pilot are analyzed. Finally, the conduction of the flight tests is described and the flown maneuvers and results are evaluated regarding the maneuver quality and the observability of the helicopter dynamics.