Research on a degradable ambulance unmanned aerial vehicle: C-wing conceptual design and flight endurance performance

This paper examines C-wing conceptual design and flight endurance performance for a degradable ambulance unmanned aerial vehicle (UAV). Considering the cargo, low- cost, and green requirements for ambulance aviation, a task requirement analysis is completed for a degradable ambulance UAV. A C-wing conceptual design strategy is proposed to serve multiple functions. The flight profile of the proposed UAV is charted to determine typical application scenes and operation methods. Conceptual design of the UAV is carried out to obtain design results of its aerodynamic configuration, mass distribution, and launch mechanism and to complete principle flight verification of a scaled-model aircraft. In accordance with the k-k_L-ω transition model, a robust solution procedure for a numerical method to analyze aerodynamic characteristics is described, and a verification study is presented. The lift‒drag and longitudinal‒lateral stability performance of the UAV is analyzed via this numerical method, and a quantitative comparison with a clean flying-wing baseline is further conducted to clarify the aerodynamic contribution of the C-wing configuration. The UAV’s flight performance, including the lift-to-drag ratio, cruise endurance factor, and longitudinal‒lateral stability, is analyzed. The UAV’s aerodynamic performance and flight profile indicate improved evaluation indicators of flight endurance capability. Flight endurance performance enhancements are obtained for typical glide and cruise ambulance missions, and excellent flight endurance performance can be obtained by applying them. The UAV’s cruise lift-to-drag ratio and endurance factor are greater than 24.5. It also has good longitudinal–lateral stability for flight endurance, and a longitudinal stability of approximately 9.2%. Compared with the clean flying-wing baseline, the C-wing configuration significantly improves both longitudinal and lateral-directional static stability while maintaining high aerodynamic efficiency, which remedies the inherent stability deficiency of conventional flying-wing layouts. The proposed C-wing degradable ambulance UAV and its design methodology demonstrate good potential for practical applications.