NGCTR-TD Tiltrotor Autorotation Numerical Investigation

Within the Clean Sky 2 Fast Rotorcraft platform, a Next Generation Civil Tilt-Rotor Technology Demonstrator (NGCTR-TD) is under development. The design phase has been successfully completed and first flight phase is planned within 2023. As part of design verification, the capability to perform a safe landing procedure after losing all engines power is investigated, with dedicated analysis planned in order to improve the transport category performance requirements, as verified for Legacy tilt-rotor platform. Such procedure consists in 4 different steps when starting from AP mode, and the analysis are focused on VTOL steady autorotation phase, being the one where tilt-rotor configuration shows higher peculiarity with respect to helicopter configuration, due to the presence of lifting surfaces. As first, preliminary considerations from helicopter theory are cited, and tilt-rotor peculiarities listed. Then, adopting the developed FlightLab numerical model, different solutions are investigated, starting from characterization in airspeed for a baseline configuration. Different sensitivity analyses are conducted to map the major effect for the specific topic, and best trade-off autorotation configuration/control strategy is obtained for NGCTR-TD. Such solution is investigated in the complete Weight/CG envelope to ensure control strategy robustness.