Mission-Focused Multidisciplinary Design Optimization of Tilt-Rotor eVTOL Propulsion System

Tilt-rotor propulsion system design requires a multidisciplinary approach to tackle important challenges and competing tradeoffs between disciplines. This paper models rotor aerodynamics, blade structures, vehicle drag, electric propulsion, and tonal/broadband acoustics for a tilt-rotor, electric vertical takeoff and landing aircraft using low-to-mid fidelity tools. The authors use gradient-based design optimization with automatic differentiation and parameter sensitivity analyses to explore the design space and complex tradeoffs of tilt-rotor distributed electric propulsion systems, exploring effects of variations in payload/empty weight, battery specific energy, and blade tip speed. This framework models multiple operating points with a mission-focused objective to account for the effects of both hover and cruise conditions on the overall system performance. Additionally, we develop a Pareto front between range and noise and observe that, for the same noise output, modeling tonal and broadband noise increases range by 3.1% when compared to using a Mach tip speed surrogate acoustics model.