Optimization of wing of GL-1 glider by utilizing adjoint method

Adjoint method is one of computational fluid dynamics-based optimization that optimizing the shape of the body. This method is rarely used in aircraft because it is still in development process. However, this research is trying to use adjoint method on GL-1 Glider which is the first national glider of Indonesia. The purpose of this research is to increase the aerodynamics performance of GL-1 with optimizing its wings. The decision to optimize the wing came from previous CFD study that the biggest contribution of lift is from wing. The ideal target of optimization is L/D, but because there is a limitation in adjoint method to use fine mesh to calculate drag accurately, then it is decided to optimize the shape with increasing lift as a target. This paper presents the result of optimization by using adjoint method. Flight condition is as resulted from previous CFD study in the maximum range condition, with velocity of 25 m/s and angle of attack of aircraft is 0 degree. By using incidence angle of 2 degree to the wing, then the optimization was done. The baseline of CL is 0.81 and CD is 0.0271. The optimized wing achieved the optimum result CL of 1.02 with CD of 0.0362 by applying adjoint method.