| Abstract [eng] |
In the evolving landscape of proprotor aircraft, especially those equipped with thrust vectoring capabilities, a transformative shift in performance and stability analysis is underway. This project focuses on developing performance analytical and numerical algorithms and introducing novel methodologies to reassess the potential and limitations of these modeling approaches against conventional ones. The central issue addressed is the standard limitation in analytical-numerical proprotor performance models, which traditionally assume small inflow angles. The project's innovation lies in developing a generic and validated tool that transcends these limitations, accommodating large inflow angles and paving the way for more accurate modeling. The project's primary objective is to advance the understanding and application of proprotor performance modeling and control systems, developing an integral unified flight dynamic model for advanced proprotor aircraft. The project unfolds through multiple sections, starting with a literature review of current modeling approaches and aircraft configurations. The following sections detail the architecture, scope, and analysis capabilities of an analytical-numerical algorithm for proprotor performance analysis with allowance for large inflow angles. This algorithm's results are then integrated into a comprehensive longitudinal rigid-body flight dynamic model, validated against experimental data, and optimized for trimming at the most aerodynamic-efficient setting. The developed proprotor optimization control system couples the RPM and collective feeding through a single input. The input proposed to be used by the algorithm or pilots in manned operations is referred to as the Power Control Stick (PCS). The control system is integrated into the longitudinal flight dynamic model, and the overall performance is evaluated against experimental data. The proposed proprotor algorithm demonstrates a significant potential improvement over conventional low-to-medium computation cost approaches, leading to remarkable error margins between -3 and 4% for the variation of power consumed versus thrust obtained. The increased accuracy enables using analytical-numerical methods in proprotor-equipped aircraft until the fine-tuning development phases are completed. This results in lower computational costs and the ease of implementing optimization cycles compared to established high computational cost approaches such as Computational Fluid Dynamics (CFD). This undertaking challenges established paradigms and establishes the groundwork for thoroughly reevaluating the methodologies employed in the analysis of proprotors' performance. Integrating the proprotor performance results into the longitudinal flight dynamic model yields error margins between 1.6% and 2.8% for hovering scenarios and 0.9% to 1.4% for the maximum speed scenarios at various pressure altitudes. Challenges arise in modeling the proprotor wake interference in hovering scenarios, particularly for tiltrotor configurations. The longitudinal flight dynamic model results are presented regarding the leading aircraft trimming parameters, stability analysis, and overall performance indicators such as the maximum speeds, ceiling, and Rate of Climb (ROC). The optimized PCS control system is designed to trim RPM and collective or feathering for maximum aerodynamic efficiency or to maximize the thrust capabilities limited by the powerplant characteristics. Comparisons with the Bell XV-15's original flight test data showcase improvements of approximately 7-8% and 2-7% for power minimization configurations in hovering and maximum speed scenarios, respectively. Configurations maximizing thrust achieve an average payload increase of 220 kg and a velocity increase of 2 m/s for hovering and maximum speed scenarios. Further exploration is recommended to assess the system's robustness and potential adaptability to varying proprotor configurations. Continued validation is crucial to solidify the practical applicability of these advancements within the broader spectrum of proprotor aircraft development. |
