Numerical simulation of static and dynamic aerodynamics for formation flight with UCAVs

Using the effect of wingtip vortex from a leading aircraft, the formation flight of unmanned combat aerial vehicles (UCAVs) can accomplish various tasks with much more efficiency. Combined with the sliding mesh technique, this paper investigates a computational fluid dynamics (CFD) method to simulate and analyze, in detail, the static and dynamic aerodynamic characteristics of formation with two flying wing models named as SACCON. Besides, the dynamic derivatives indicating the dynamic stability of aircrafts in formation are identified and validated, and normal single flights are also analyzed as a comparative study. The results demonstrate that, due to the wake of the leader, significant enhancements of the wingman are achieved, in terms of the lift-to-drag ratio, pitching, rolling, and yawing moments in steady states, but the static stabilities are reduced as unbalanced moments. Moreover, compared with a single aircraft, the unsteady sinusoidal motions indicate that the dynamic aerodynamics and its corresponding dynamic derivatives change in a much more complex manner. It is concluded that the initial angle of attack and distance in the formation flight are the main factors to evaluate the effect, which should be monitored and adjusted in real time for better use of the profit of formation, especially in dynamic maneuvering.