This chapter briefly details the third force in an aeroelastic model, an aerodynamic force. The chapter starts with basic concepts and governing equations for fluid dynamics. Aerodynamics is a subject for external flow studies based on the Navier–Stokes equations, which are simplified by means of a small-perturbation technique leading to a potential flow equation for aircraft applications. The scope of this chapter is limited to subsonic aerodynamics, where these concepts can be further implemented for supersonic analysis with some modifications. The linearised potential flow differential equation is solved by using a panel-based approach. For steady aerodynamics, a vortex ring method is presented. The unsteady version of the vortex ring method, which is termed the frequency-domain vortex ring method, is also provided. The doublet lattice method for subsonic unsteady aerodynamics is detailed. All the panel methods are presented, emphasising computational concepts rather than theoretical aspects.