Multiscale Design and Optimization of a VTOL Aircraft for Disaster Relief

This paper presents a multi-scale sizing and optimization framework for a vertical take-off and landing (VTOL) aircraft designed for disaster-relief operations, addressing both conceptual full-scale design and feasibility analysis of a subscale prototype. A tandem tilt-wing configuration with eight distributed propulsors is considered in the context of the GoAero Stage 2 mission. The full-scale aircraft employs a hybrid-electric propulsion architecture centered around a Rotax 916 iS engine, with propulsion and energy system components sized to satisfy point-performance, mission, and dynamic maneuvering requirements. The aircraft is sized and optimized using the Parametric Energy-Based Aircraft Configuration Evaluator (PEACE), which integrates aero-propulsive modeling, energy-based mission analysis, and power-flow-based propulsion sizing. Hover maneuvering constraints based on ADS-33E-PRF are explicitly enforced and are shown to be a dominant driver of motor and propulsion system sizing. Batteries are sized to support power-intensive off-nominal conditions, including engine-out vertical climb. A genetic algorithm is used to solve optimization problems involving continuous and discrete design variables, with maximum takeoff mass and range as multiple objectives. For the full-scale design, stall speed is identified as the dominant active constraint in the optimal design. The optimized configuration is subsequently scaled down by 35% to obtain a subscale prototype. In contrast to full-scale rubber-propulsion sizing, the subscale design adopts a fixed-propulsion sizing approach using commercial off-the-shelf components. The resulting design satisfies all geometric, performance, stability, and payload constraints while remaining within regulatory mass limits of 55 lbs.