Publications

When designing a vertical takeoff and landing (VTOL) aircraft, it is crucial to consider various operating conditions, including hover, wing-borne cruise, and transition. Takeoff transition and climb phases are critical for vehicle conceptual design because they drive the motor and battery sizing. However, these flight phases are often ignored or simplified in the conceptual design literature due to the complexity of transition dynamics. To address this limitation, we propose simultaneous optimization of VTOL aircraft conceptual design and takeoff trajectory. Simultaneous optimization incorporates the takeoff transition and climb flight dynamics into VTOL design optimization in a fully coupled manner. This paper presents the design-trajectory optimization of lift-plus-cruise and tailsitter UAVs for delivery missions. As a result, simultaneous optimization reduces total energy consumption by 7.4% compared to uncoupled optimization and by 4.8% from iterative sequential optimization in the lift-plus-cruise configuration. It also achieves a 29% energy reduction from uncoupled optimization in the tailsitter configuration. Incorporating takeoff trajectory optimization in UAV sizing enables accurate estimation of takeoff and climb energy, which avoids undersizing or oversizing the battery. Furthermore, simultaneous optimization trades the vehicle weight penalty for a more energy-efficient climb with early transition. These system-level trade-offs can only be captured by simultaneous optimization; they cannot be captured by uncoupled or iterative sequential optimization.