An aeroelastic analysis of a model that uses a combination of horizontal and vertical tails is performed in a transonic flow regime. A transonic small disturbance equation is used for the aerodynamic analysis. The combined model is divided into horizontal tail and vertical tail blocks because the transonic small disturbance equation can only be applied to models with lifting surfaces on identical or parallel planes. Nonmatching grid points are positioned on each interface between the horizontal and vertical tail blocks. To form a transonic small disturbance equation continuously at the interfaces, each block requires imaginary planes with potential interfaces with the adjacent block and the grid points on the block interface. A bivariate interpolation method was used to construct the imaginary planes. The aerodynamic analysis results of the combined model are compared with the results obtained from Euler equations. The results show that the transonic small disturbance equation can be used in an aerodynamic analysis of a combined model with horizontal and vertical lifting surfaces. Finally, the aeroelastic characteristics of the horizontal tail are investigated using comparisons of the time responses between the combined model and the horizontal tail model.