This paper presents the development of a three-dimensional aerodynamic model and a computational fluid dynamics (CFD) procedure for a combat aircraft in the clean configuration, without external weapon or fuel-store attachments. The aircraft geometry is developed in SolidWorks and coupled with ANSYS CFX to define the computational domain, mesh, and boundary conditions. Compressible-flow calculations are performed at an altitude of 4 km, Mach numbers of 0.4 and 0.8, angles of attack from 0° to 21°, and a zero sideslip angle. For the clean configuration, the lift coefficient Cy varies with angle of attack in three characteristic stages. At Mach 0.4, Cy increases approximately linearly up to 15°, then increases more slowly until about 18°, after which it decreases. At Mach 0.8, the corresponding transition points are approximately 10° and 20°. Local supersonic regions and shock waves appear on the wing at Mach 0.8, causing earlier boundary-layer separation and reducing the maximum lift coefficient and critical angle of attack compared with Mach 0.4. The obtained results characterize the baseline aerodynamic behavior of the aircraft without external attachments.

Le Thanh Nguyen, Duc Dung Nguyen, Trung Duc Pham,"Aerodynamic Characteristics of a Combat Aircraft in the Clean Configuration Using Computational Fluid Dynamics" International Journal of Advanced Multidisciplinary Research and Educational Development, V2(4): Page(611-613) July - August 2026. ISSN: 3107-6513. www.ijamred.com. Published by Scientific and Academic Research Publishing.