This article introduces an original model-based design methodology addressing a high-performance aircraft design challenge: conflicting performance requirements. The case study of the Global 7500 elevator actuation system also provides in-depth insight into the complex design process of today’s fly-by-wire flight control systems. The methodology presented here redefines the aircraft manufacturer’s involvement in the design process of the systems, implementing analysis and iteration capabilities early in system development. To this end, it introduces a novel modeling approach for analyzing loaded rate requirements by simulating closed-loop performance with a generic nonlinear second-order state filter, including the main performance limitations without requiring a preliminary design definition. In this way, it provides means to mature the system requirements and addresses requirement conflicts upfront. Then, a simulation-based preliminary sizing and performance assessment validates the candidate design concept. It also secures the preliminary design phase by implementing advanced design uncertainties and involving interfacing systems and disciplines early in the process. The redefined methodology identified directly that the problem’s root cause was a conflict between stability and control and flutter protection requirements. It also indicated that the first sizing driver is the response time required under a specific failure case. These findings lead to an optimal elevator actuator design compliant with matured performance requirements. Thus, the methodology resolved a design challenge blocking the Global 7500 aircraft development and prevented redesign occurrences later during the detailed design phase. In this way, it directly contributed to the successful development of the Global 7500 and its optimal operational performance. This methodology applies to future aircraft design challenges, and the technical insight provides valuable lessons learned for high-performance T-tail business jets.

Unmanned Aerial Vehicles (UAVs) are increasingly utilized across various industries, necessitating high reliability to ensure safety and reduce operational costs. This paper introduces a systematic methodology for physics-based reliability modeling tailored for UAV control applications, focusing on adaptive control allocation to optimize reliability. The study addresses the limitations of conventional degradation-independent behavior factor-based models, which often rely on inaccurate degradation models due to the lack of parameterization data sources and methods. By replacing time with stress-derived variables in the reliability function, this approach enables the combination of any time-dependent reliability functions with any stress-life relationships, allowing for real-time physics-based reliability assessments. The approach is demonstrated through the development and application of models for electronic speed controllers within a hexarotor UAV, using a virtual prototype for flight simulation. Simulation results reveal that physics-based models improve reliability prediction accuracy compared to conventional proportional hazard models, particularly due to their reliance on published and manufacturer’s data for parameterization. The paper concludes by highlighting the need for future research to simplify the integration of stress factor online measurements, addressing the complexity and data requirements inherent in physics-based models.

The increasing use of drones for safety-critical applications, particularly beyond visual lines of sight and over densely populated areas, necessitates safer and more reliable designs. To address this need, this paper introduces a novel methodology integrating Null Controllability with the Model-Based Safety Assessment (MBSA) framework AltaRica 3.0 to optimize propulsor configurations and system architectures. The main advancement of this method lies in the automation of reliability modeling and the integration of controllability assessment, eliminating restrictions on the types of propulsor configurations and system architectures that can be evaluated and significantly reducing the effort required for each design iteration. Through a hexarotor drone case study, the proposed method enabled a high number of design iterations, efficiently exploring various aspects of the design problem simultaneously, such as configuration, system architecture, and controllability hypothesis, which is not possible with state-of-the-art techniques. This approach demonstrated significant reliability improvements by implementing and optimizing redundancies, reducing the probability of loss of control by up to 99%. The case study also highlighted the increasing difficulty of enhancing reliability with each iteration and confirmed that it is unnecessary to consider more than two simultaneous failures for design optimization. A comparison of reliability figures with previous studies highlights the crucial role of system architecture in effectively enhancing drone design reliability. This work advances the field by providing an effective multidisciplinary modeling framework for drone design, enhancing reliability in safety-critical applications.

This article presents a methodology for analyzing the controllability and fault-tolerant sizing of fixed-wing and hybrid fixed-wing vertical landing and takeoff (FW-VTOL) unmanned aerial vehicles (UAVs). Building upon previous research focused on multirotor UAVs, the study introduces a new control authority index, redefined dynamics models, and enhanced control allocation techniques to address rotor failures and lock-in-place failures of control surfaces. The methodology considers effector limitations and the unidirectional drag condition for control surface deflection angles.These advancements are combined to assess the linear controllability and accomplish fault-tolerant sizing of UAVs. By applying the proposed methodology to a case study, the linear controllability of fixed-wing and hybrid FW-VTOL UAVs is evaluated in various failure scenarios. The results demonstrate that the hybrid FW-VTOL concept exhibits higher fault tolerance capability due to the presence of VTOL rotors that can compensate for control surface failures. The study emphasizes the importance of oversizing VTOL rotors to ensure sufficient control authority in double failure scenarios, revising the conventional assumption that VTOL system sizing primarily relies on takeoff analysis.The proposed advancements are relevant to future UAV designs intended for fault-tolerant applications such as medical equipment transport and air taxis.