Patent ID: 8437894

Claim:
A method for improving the performance of an aircraft during a take-off phase, said aircraft being provided with aerodynamic control surfaces (S 1 -Sn) able to have a plurality of separate predetermined take-off positions (P 1 , P 2 , P 3 ), each of which corresponds to predefined deflections of said control surfaces (S 1 -Sn), wherein, before take-off, the following steps are automatically performed: determining a recommended value of the initial rate of climb (V 2 ) of said aircraft, such that at least the following regulatory safety criteria are respected upon take-off: said recommended value of the initial rate of climb (V 2 ) is at least equal to a first predefined speed threshold which is a function of the stalling speed of said aircraft; said recommended value of the initial rate of climb (V 2 ) is at least equal to a second predefined speed threshold which is a function of the minimum control speed with a breakdown engine; the minimum gradient of climb of said aircraft with a breakdown engine is at least equal to a predefined gradient threshold; and selecting among said separate predetermined positions (P 1 , P 2 , P 3 ) a take-off position and applying said take-off position to said control surfaces (S 1 -Sn), wherein: a preliminary step comprises checking whether the safety criterion relating to said minimum gradient of climb with a breakdown engine is predominant with respect to other safety criteria using a theoretical representation (C 1 , C 2 , C 3 ) of the take-off mass variations (M) of said aircraft according to the initial rate of climb (V 2 ) thereof, combined with said selected take-off position (P 1 , P 2 , P 3 ); and in the case where the minimum gradient of climb with a breakdown engine is a predominant safety criterion, the following steps are performed: i) comparing a predefined value of the initial rate of climb (V 2 ) with said first speed threshold; ii) when the deviation between the predefined value of said initial rate of climb (V 2 ) and said first speed threshold is substantially different from zero, determining optimised deflection commands of said control surfaces (S 1 -Sn), defining an optimal take-off position (Popt), so as to reduce said deviation upon take-off, with these optimised deflection commands being such that they generate an optimised deflection of said control surfaces less than that of said selected position; and iii) applying the optimised deflection commands thus determined to said control surfaces (S 1 -Sn), whatever said previously selected take-off position (P 1 , P 2 , P 3 ).