Handling Qualities Analysis of a Large Multi-Rotor eVTOL Using RPM, Collective and Cyclic Control Allocation Methods

The Eagle Flight Research Center (EFRC) at Embry-Riddle Aeronautical University (ERAU) is investigating the handling qualities of partial and full rotor failure modes of a multi-rotor vehicle testbed employing Distributed Electric Propulsion (DEP) systems intended for Advanced Air Mobility (AAM) vehicles. In order to pave the way for commercial operations, the AAM industry requires a deeper understanding of the handling characteristics and the vehicle's dynamics and controllability under rotor failure conditions. The objective of the research performed at the EFRC centered around designing and testing different thrust and moment control allocation methods for an electric Vertical Take-Off and Landing (eVTOL) vehicle, in addition to assessing their performance in both nominal and failure modes of operation. This paper focuses on analyzing the predicted handling qualities for a full-scale quadrotor testbed vehicle with RPM, collective, and cyclic blade pitch control allocation. The study uses flight-test data to develop a bare airframe dynamic model to optimize the controller gains, which are used to evaluate the predicted handling qualities though development of vehicle specific Handling Qualities Task Elements (HQTE) maneuvers. The evaluation is performed using an in-house built flight simulator together with the Cooper-Harper Rating Scale (CHRS) for Handling Qualities test evaluation. The handling qualities were evaluated and compared for different control strategies and a method for quantitative evaluation of handling qualities is presented.