Tight Formation Flight Control

Abstract

Thetightformatione ightcontrolproblemisaddressed.Theformationconsistsofa lead andwingaircraft,where the wing e ies 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 face of lead aircraft maneuvers. In the formation e ight control 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 signie cant aerodynamic coupling effect introduced by tight formation e ight entails the coupling of the lateral/directional channel into the altitudehold autopilot channel. It is shown that formation-hold autopilots designed ignoring the aerodynamic coupling effect yield satisfactory performance in tight formation e ight. Nomenclature b = wingspan of wing CLL = lift coefe cient of the lead aircraft S = surface area of wing VSW = sidewash W = wash vector WUW = upwash