Uav Formation Of Aerodynamic Coupling

This dissertation develops a new technique for the aerodynamic coupling modeling and incorporates it into a six-DOF analysis of a close formation flight. The velocities induced by the leader's wingtip vortex on the following aircraft are written as a function of the relative separation in the three axial directions and also the relative orientation between the leader and the follower aircraft using a modified horseshoe vortex model based on Biot-Savart law. Since the induced wind and wind gradient are non-uniform, hence a weighted averaging method is used to compute effective wind components and wind gradient at the CM(centre of mass) of the encountering aircraft. Then, the effective wind components and gradients are introduced into the standard six-DOF nonlinear aircraft kinematics equations and dynamics equations to determine the effects on the follower's dynamics induced by the wingtip vortex of leader aircraft.Our model could adapt different types for the leader and the follower aircraft and also include many major geometrical parameters of the aircraft like the wing sweep angle, the dihedral angle and the relative distance between the CM of the aircraft and the aerodynamic center of the wing. We also consider the effect of vortex decay over time caused by the viscidity of atmosphere in our vortex model in estimating the vortex effect experienced during the close proximity formation flight.A comparison study has been presented which shows that the induced forces and moments computed by our method qualitatively and in some cases quantitatively sufficient matching well with the wind tunnel experiment.At last, the modified six-DOF nonlinear aircraft equations which could load the effective wind and wind gradient directly has been brief introduced.The method this thesis presented could conveniently extend to the research of aerial refueling and air traffic security.