Method and device for piloting an aircraft optimizing the control of the ailerons in an enhanced-lift configuration
View Patent ↗In conformance with the invention, based on the incident conditions and velocity, the steering of the ailerons is weakly negative (b 0 ) or corresponds either to the maximum sharpness of the aircraft (b 1 ), or the optimal lift of the latter (b 2 ).
1. A method for piloting an aircraft, in which the aircraft comprises two symmetric wings, with each wing having:
movable lift-enhancing aerodynamic surfaces, configured to provide said wings either a smooth configuration, or at least one enhanced-lift configuration; and
roll control ailerons, configured to provide a neutral position that corresponds to a zero deflection, when said wings exhibit said smooth configuration,
the method comprising the steps of:
providing the enhanced-lift configuration to said wings:
when incidence and speed of the aircraft are respectively less than an incidence threshold and greater than a speed threshold, a first state corresponding to a position deflected upwards by an angle such that roll effectiveness of said ailerons is preserved; and
when incidence of the aircraft is equal to or greater than said incidence threshold or when the speed of the aircraft is equal to or less than said speed threshold, a second state corresponding to at least one of:
a first downward deflection value corresponding to maximum finesse (Fmax) of the aircraft during takeoff or re-takeoff phase, and
a second downward deflection value corresponding to optimal lift of the aircraft during landing phase.
2. The method as claimed in claim 1 , wherein the position of the incidence α with respect to said incidence threshold as is determined by comparing the expression α+K 1 ·q with said threshold αs, K 1 being a positive constant coefficient and q being the pitch rate of said aircraft.
3. The method as claimed in claim 2 , wherein said incidence threshold as depends on the position of said lift-enhancing aerodynamic surfaces and the Mach number.
4. The method as claimed in claim 1 , wherein the position of the speed Vc of the aircraft with respect to said speed threshold Vs is determined by comparing the expression Vc+K 2 ·dVc/dt with said threshold Vs, K 2 being a positive constant coefficient and dVc/dt the acceleration of said airplane.
5. The method as claimed in claim 4 , wherein said speed threshold (Vs) depends on the position of said lift-enhancing aerodynamic surfaces and the Mach number.
6. The method as claimed in claim 1 , wherein, after being switched from said first state to the second, said ailerons remain in said second state even if the incidence and speed conditions again become in accordance with said first state.
7. The method as claimed in claim 1 , wherein, after being switched from said first state to the second, said ailerons switch back to said first state when the incidence and speed conditions again become in accordance with said first state.
8. A device for implementing the method of claim 1 , the device comprising:
first comparator that compares said incidence α with said incidence threshold αs;
second comparator that compares said speed Vc with said speed threshold Vs;
OR type logic gate that receives results of the comparisons performed by said first and second comparators;
first switching unit that chooses between said first deflection and said second deflection; and
second switching unit, actuated by said logic unit that chooses between results the first switching unit and said position deflected upwards by an angle such that said ailerons preserve roll effectiveness.
9. An aircraft, comprising a device that implements the method of claim 1 .