無人戰鬥飛行載具（Unmanned Combat Aerial Vehicle ,UCAV）為現代空中作戰發展的重要趨勢之一。UCAV 為一種具備執行軍事作戰任務能力的無人飛行載具，其主要任務包含戰場偵察、監視、目標打擊以及情報蒐集等，因此在現代軍事行動中扮演著日益重要的角色。UCAV 具有多種不同構型，其中Λ翼構型因具備較佳的氣動效率與隱形潛力而受到廣泛關注。本研究以 Stability And Control CONfiguration（SACCON）為研究對象，為提升其整體氣動性能，採用計算流體力學（CFD）數值模擬方法，並結合伴隨算子方法（Adjoint Method）進行外形最佳化設計，以提升飛行器之升阻比L/D為主要優化目標。
研究結果顯示，經由伴隨方法進行外形優化後，SACCON 構型的升阻比確實獲得提升3.25%，顯示該方法在氣動性能優化上具有良好效果。初始外型在高攻角下會產生低頭力矩的現象，然而優化後的外形使得此低頭力矩驟增造成不連續現象，導致飛行器控制性有所降低。為改善此問題，本研究以 SACCON 構型為基礎，進一步提出一種具非固定前緣後掠角之新型外形設計，並設計出兩種非固定前緣後掠角外型，再將優化後 SACCON 外形的特徵整合至該新構型之中。分析結果顯示升阻比各提升2.58%及1.9%，且低頭力矩變化幅度較初始外型低，顯示飛行穩定性獲得一定程度的改善。本研究結果顯示，伴隨算子方法應用於Λ翼構型無人飛行載具之氣動外形設計具有良好潛力，可作為未來無人飛行載具氣動設計與最佳化研究之重要參考方法。

Unmanned Combat Aerial Vehicles (UCAVs) are one of the important development trends in modern aerial warfare. A UCAV is a type of unmanned aerial vehicle capable of executing military combat missions. Its primary missions include battlefield reconnaissance, surveillance, target strike, and intelligence collection; therefore, it plays an increasingly important role in modern military operations. UCAVs have various configurations, among which the lambda-wing configuration has attracted widespread attention due to its superior aerodynamic efficiency and stealth potential. The Stability and Control Configuration (SACCON) is adopted in this study. To improve its overall aerodynamic performance, Computational Fluid Dynamics (CFD) numerical simulation methods are employed, combined with the adjoint method for shape optimization design, with the lift-to-drag ratio (L/D) as the main optimization objective.
The results show that, after shape optimization using the adjoint method, the lift-to-drag ratio of SACCON configuration is indeed improved, with L/Dincrease of 3.25%, demonstrating that this method has good effectiveness in aerodynamic performance optimization. However, the optimized shape also leads to a reduction in the controllability of the vehicle. Due to the pitching moment discontinuity at high angle of attack. To address this issue, a nonconstant leading-edge sweep angle configuration based on the SACCON configuration is proposed. The design features a lambda-wing with a double sweep angle, commonly referred to as a “cranked lambda-wing.”. Lambda-wing with a double sweep angle design combines a high-sweep inboard section (for example from Λ1=67° to 73° in this study) and a lower-sweep outboard section (for example Λ2=53° in this study)
The characteristics of the optimized SACCON shape are then integrated into these new lambda-wing with a double sweep angle configurations. The analysis results show lambda-wing with a double sweep angle leads to the lift-to-drag ratio increase of 2.58% for (Λ1=67° and Λ2=53°) and 1.9% (Λ1=73° and Λ2=53°), respectively, and that flight controllability compare with initial SACCON is improved to a certain extent. The results of this study indicate that the application of the adjoint method to the aerodynamic shape design of lambda-wing UCAV has good potential and can serve as an important reference method for future research on aerodynamic design and optimization of uninhabited aerial vehicles.

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