Evaluating one engine inoperative conditions in subscale electric vertical take-off and landing aircraft: An in-depth tethered hover test analysis

The direction of propeller rotation in a distributed electric-powered vertical take-off and landing (eVTOL) aircraft significantly influences control forces and induced drag during both helicopter and fixed-wing modes. This study proposes a strategy to determine the most effective rotational direction for each propeller. This approach effectively mitigates one-engine-inoperative (OEI) conditions during helicopter mode for a subscale eVTOL referred to as the optionally piloted personal air vehicle (OPPAV). Moreover, the study developed an optimal control law using the linear programming method, which minimizes the maximum power required for individual motors under OEI conditions. The lowest maximum power was achieved under OEI conditions when both the front and rear propellers in each pod rotated in the same direction. Furthermore, to validate this proposed control law, a tethered hover test was performed using the subscale OPPAV under OEI conditions. Our findings demonstrate that determining the rotational direction of propellers using the newly proposed reconfiguration control method significantly enhances the safety of eVTOL aircraft operating under OEI conditions.