Patent ID: 8527116

Claim:
A process for optimising the performances of an aircraft (A) in the presence of a lateral dissymmetry, during a flight of the aircraft (A), comprising automatically, via a device on-board the aircraft: a) monitoring said aircraft (A) such that the lateral dissymmetry can be detected; b) when a lateral dissymmetry is detected, measuring flight parameters of the aircraft (A), on the one hand, for calculating aerodynamic coefficients relating to control surfaces ( 18 ) of the aircraft (A), and on the other hand, measuring an equilibrium position of said control surfaces ( 18 ), said control surfaces ( 18 ) being preliminary brought to these positions for minimising effects of the lateral dissymmetry by generating a null sideslip of the aircraft (A); c) using said measured flight parameters, aerodynamic coefficients relating to said control surfaces ( 18 ) are calculated; d) using said thus calculated aerodynamic coefficients and said measured positions of the control surfaces ( 18 ), an optimum sideslip βop likely to generate a sideslipping for minimising an overall drag coefficient of the aircraft (A) is calculated using the following expression: β op =−( Cλδp 1 ·δp 1 +Cλδr+Cλδp 2 ·δp 2)/ Cλβ wherein: δp 1 and δp 2 are the equilibrium positions of roll control surfaces ( 18 A, 18 B) of the aircraft (A) ; δr is the equilibrium position of a rudder ( 18 C) of the aircraft (A); Cλδp 1 , Cλδp 2 and Cλδr are the aerodynamic coefficients relating respectively to the roll control surfaces ( 18 A, 18 B) and the rudder ( 18 C); and Cλβis the derivative of the roll moment coefficient with respect to the sideslip; e) determining commands for controlling at least one rudder ( 18 C) for generating said optimum sideslip βop, when they are applied to said rudder ( 18 C); and f) applying said commands to said rudder ( 18 C).