Preliminary design and analysis of crashworthy structures for a long-range eVTOL aircraft

In aircraft structural design it is of utmost importance to minimise the structural mass while maintaining a durable structure that is able to sustain the design loads for a predetermined number of flight cycles. The present manuscript investigates a methodology for the preliminary design and analysis of a tandem-wing long-range electric vertical takeoff and landing (eVTOL) aircraft. First, a class I weight estimation for initial loads calculation is presented. Next, the flight envelope, main load cases and failure modes considered in this preliminary design are explained. Load approximations for the wing structures in cruise and take-off conditions are presented and discussed. Next, Cessna's class II semi-empirical weight estimation method is applied to calculate the mass of 11 eVTOL aircraft subsystems. A design concept for the wing tilting mechanism is proposed. Thereafter, an initial fuselage layout design is presented, followed by a discussion on design for crashworthiness. The aeroelastic behaviour of the wing and the whirl flutter considering the propeller engine structures is investigated. Lastly, refinements in the design parameterization are implemented concerning the thickness distributions in the structural elements of the wingbox, and finally a sizing of the wing rotating shaft is performed.