Tight formation flight control

The tight formation flight control problem is addressed. The formation consists of a lead and wing aircraft, where the wing flies in tight formation with the lead, such that the lead's trailing vortices aerodynamically couple the lead and the wing, and a reduction in the formation's induced drag is achieved. A controller (i.e., a formation-hold autopilot for the wing aircraft) is designed such that the formation's geometry is maintained in the fate of lead aircraft maneuvers. In the formation flight central system, the wing and lead aircraft dynamics are coupled due to kinematic effects, and, in the case of tight formations, additional aerodynamic coupling effects are introduced. These additional aerodynamic coupling effects are properly modeled. The most significant aerodynamic coupling effect introduced by tight formation flight entails the coupling of the lateral/directional channel into the altitude-hold autopilot channel. It is shown that formation-hold autopilots designed ignoring the aerodynamic coupling effect yield satisfactory performance in tight formation flight.