Method for assisted piloting of an aircraft provided with a rotary wing and a propulsion unit comprising at least one propulsion propeller, each propeller comprising a plurality of first blades, the rotary wing comprising at least one rotor provided with a plurality of second blades, in said method an order of a pilot of the aircraft given to request a movement along a longitudinal or vertical direction is translated into an acceleration setpoint along said direction, and then this acceleration setpoint is transformed by predetermined relationships into at least one setpoint for maintaining longitudinal attitude (θ*) transmitted to a first automatic system for maintaining longitudinal attitude controlling a longitudinal cyclic pitch of the second blades of the rotary wing in order to comply with said setpoint for maintaining longitudinal attitude (θ*) and into a first setpoint for maintaining load factor (Nx*) in a longitudinal direction of the aircraft parallel to a roll axis of said aircraft transmitted to a second automatic system for maintaining said load factor controlling a collective pitch of the first blades of the propulsion unit in order to comply with said first setpoint (Nx*), in which method said order is an order to move along a longitudinal direction of the aircraft parallel to a roll axis of said aircraft, this order to move along a longitudinal direction is translated into a longitudinal acceleration setpoint, and then this longitudinal acceleration setpoint is transformed by predetermined relationships solely into a setpoint for maintaining longitudinal attitude (θ*) transmitted to a first automatic system for maintaining longitudinal attitude and into a first setpoint (Nx*) for maintaining load factor, said method characterised in that: said setpoint for maintaining longitudinal attitude (θ*) is determined by the following first longitudinal control relationship: θ * = 180 / Pi • − a • γ x * / g − k / a + b where "θ*" represents the setpoint for maintaining longitudinal attitude expressed in degrees, "Pi" represents the number π, "γ x *" represents the longitudinal acceleration setpoint, "g" represents the acceleration due to gravity, "·" represents the multiplication sign, "/" represents the division sign, "a" represents a first longitudinal constant, "b" represents a second longitudinal constant, "k" represents a third longitudinal constant. and/or, said first setpoint for maintaining load factor (Nx*) is determined by the following second longitudinal control relationship: Nx * = b • γ x * / g − k / a + b where "Nx*" represents said first setpoint for maintaining load factor, "γ x *" represents the longitudinal acceleration setpoint, "g" represents the acceleration due to gravity, "•" represents the multiplication sign, "/" represents the division sign, "a" represents a first longitudinal constant, "b" represents a second longitudinal constant, "k" represents a third longitudinal constant, said method being further characterised in that the third longitudinal constant "k" is determined by the following formula: k = − sin θ equi • a + b, where "•" represents the multiplication sign, "a" represents said first longitudinal constant, "b" represents said second longitudinal constant, and "θ equi " represents a predetermined equilibrium attitude optimizing the performance of the aircraft in predetermined stabilized flight phases, the longitudinal acceleration setpoint (γ x *) being zero said setpoint for maintaining longitudinal attitude (θ*) is determined by the following first longitudinal control relationship: θ * = 180 / Pi • − a • γ x * / g − k / a + b where "θ*" represents the setpoint for maintaining longitudinal attitude expressed in degrees, "Pi" represents the number π, "γ x *" represents the longitudinal acceleration setpoint, "g" represents the acceleration due to gravity, "·" represents the multiplication sign, "/" represents the division sign, "a" represents a first longitudinal constant, "b" represents a second longitudinal constant, "k" represents a third longitudinal constant. said first setpoint for maintaining load factor (Nx*) is determined by the following second longitudinal control relationship: Nx * = b • γ x * / g − k / a + b where "Nx*" represents said first setpoint for maintaining load factor, "γ x *" represents the longitudinal acceleration setpoint, "g" represents the acceleration due to gravity, "•" represents the multiplication sign, "/" represents the division sign, "a" represents a first longitudinal constant, "b" represents a second longitudinal constant, "k" represents a third longitudinal constant, said method being further characterised in that the third longitudinal constant "k" is determined by the following formula: k = − sin θ equi • a + b, where "•" represents the multiplication sign, "a" represents said first longitudinal constant, "b" represents said second longitudinal constant, and "θ equi " represents a predetermined equilibrium attitude optimizing the performance of the aircraft in predetermined stabilized flight phases, the longitudinal acceleration setpoint (γ x *) being zero