A REVIEW ON SURFACE TEXTURES IN AIRCRAFT IMPROVING AERODYNAMIC EFFICIENCY

Improving the lift-to-drag (L/D) ratio is a fundamental objective in aircraft design due to its strong influence on fuel efficiency, operating cost, and environmental impact. While traditional aerodynamic optimization methods, such as airfoil and wing geometry refinement, have achieved significant improvements, they are often constrained by structural and design limitations. As a result, surface microstructures have emerged as an effective complementary approach for enhancing aerodynamic performance without major changes to the overall aircraft configuration. Surface microstructures interact directly with the boundary layer, where most drag generation and flow separation occur. Commonly studied examples include riblets, micro-vortex generators, surface grooves, dimples, and bio-inspired textures such as sharkskin-like patterns. Riblets are particularly effective in reducing skin-friction drag by limiting the spanwise motion of near-wall vortices in turbulent flow, leading to improved L/D ratio during cruise conditions. Other microstructures, such as micro-vortex generators, help energize the boundary layer and delay flow separation, improving lift performance at higher angles of attack. Advances in materials and manufacturing technologies, including laser surface texturing and additive manufacturing, have made it increasingly feasible to fabricate and apply these microstructures on aircraft surfaces. Experimental and computational studies indicate that well-designed micro structured surfaces can reduce viscous drag, delay separation, and maintain efficient lift generation across a range of flight conditions. Although challenges related to durability and sensitivity to operating conditions remain, surface microstructures offer a promising pathway toward more efficient and sustainable aircraft design.