In aircrafts with multiple wings, control surfaces, and stabilizers, the stabilizing fins located at the tail provide stability for the boosting. In such aircrafts, the vortices resulting from the flow around upstream wings and control surfaces usually weaken the stabilizers’ performance. The nature of the form of grid fins makes them less sensitive in comparison with planar fins. Accordingly, the performance can be improved by substituting grid fins for planar fins. This paper simulates the flow field around the different models of planar and grid fins by applying finite volume methods using hybrid grid near the airplane’s body. At first, the flow field around a model with available experimental results was simulated to achieve the appropriate model of turbulence model. Then, two set of planar stabilizers, i.e. PL1 and PL2 and one set of grid stabilizers were designed for an aircraft with wings and control surfaces in a way that aerodynamic coefficients of the fins are equal to each other. However, they demonstrate different aerodynamic coefficients when installed on the aircraft as stabilizers. The simulation was run at Mach numbers 0.6, 0.7, and 0.8 and attack angles 0, 2, 4, and 6 degrees. The results indicate that pitch moments and normal force coefficients of the planar fin are lower than the grid fin in both models. Moreover, the performance of the planar fin as a stabilizer will be improved if its chord’s length is decreased and its span is increased.