Abstract
This paper puts forward an aerodynamic design method to improve the high-speed aerodynamic performance of an aircraft with low-aspect-ratio tailless configuration. The method can ameliorate the longitudinal moment characteristics of the configuration by designing and collocating the key section airfoils with the constrains of fixed parameters of planform shape and capacity. Firstly, the effect of twisting the wing, fore-loading and aft-reflexing key section airfoils on the high-speed aerodynamic performance of the configuration is evaluated by high-fidelity numerical methods, and quantified by defining trimming efficiency factors. Then, a linear superposition formula is obtained by analyzing the effect rule of trimming efficiency factor, and based on the formula the design and collocation methods of key section airfoils are achieved. According to the methods, a trimmed configuration is obtained. The results of computational fluid dynamics (CFD) and wind tunnel tests show that the trimmed configuration has smaller zero-lift pitching moment and higher available lift-to-drag ratio than the initial configuration at cruise, besides the trimmed configuration achieves the design principle raised for tailless configuration, which can be described as the zero-pitching moment, cruising design lift coefficient, and maximum lift-to-drag ratio are coincident. In addition, at off-design conditions, the trimmed configuration shows favorable drag divergence characteristics, satisfactory aerodynamic characteristics at medium-altitude maneuvering condition, and good stall and pitching-moment performance at low speed state.
Highlights
The essential prerequisites for advanced fighter aircraft are excellent aerodynamic performance, strong maneuverability, and favorable stealth performance
This study focuses on the aerodynamic design of a low-aspect-ratio tailless configuration based on the principle [8] for tailless configuration that the zero-pitching moment, cruising design lift coefficient, and maximum lift-to-drag ratio are coincident
To verify the simulative ability and the numerical computing capacity of the subsonic and transonic methods, the Low Speed Straked Delta Wing (LSSDW) model provided by National Aerospace Laboratory NLR [24] and the delta wing model provided by the Second International Vortex Flow Experiment (VFE-2) [25] are used
Summary
The essential prerequisites for advanced fighter aircraft are excellent aerodynamic performance, strong maneuverability, and favorable stealth performance. The design idea that the cruise point, maximum lift-todrag ratio point, and pitch trim point should lie along the same flight attitude, was firstly put forward for BWB aerodynamic design [8] Based on this idea, numerous practical aircraft were designed by optimizing the planform and airfoil design [2,8,9]. For a low-aspect-ratio tailless configuration, the constraints should include the requirement for aerodynamics and structure, such as lift-to-drag ratio, pitching trim, and loading, and the requirement for Radar stealth, which is mainly decided by the planform shape of the configuration [10].
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