초록 ▼

A static longitudinal stability (SLS) system provides an unobtrusive airspeed hold function that reacts to the pilot control inputs into the flight control system and the measured states of the aircraft to engage and disengage smoothly without any explicit mode selection by the pilot. The SLS engage

A static longitudinal stability (SLS) system provides an unobtrusive airspeed hold function that reacts to the pilot control inputs into the flight control system and the measured states of the aircraft to engage and disengage smoothly without any explicit mode selection by the pilot. The SLS engages airspeed hold when the aircraft is close to trimmed, non-accelerating state. This logic allows the pilot to either fly close to a desired airspeed and let SLS engage, or trim the aircraft in an accelerating/decelerating maneuver and just wait for the SLS to capture a speed when longitudinal acceleration is small. The SLS is not dependant on the pilot specifically selecting this mode, but rather engages and disengages in response to flight control system status and how the aircraft is being maneuvered.

대표청구항 ▼

What is claimed is: 1. A method of providing an airspeed hold function for a fly-by-wire system of a rotary-wing aircraft comprising the steps of: (1) determining when absolute pitch, roll and yaw rate are each below a predetermined value; (2) stopping a pre-existing aircraft acceleration or decele

What is claimed is: 1. A method of providing an airspeed hold function for a fly-by-wire system of a rotary-wing aircraft comprising the steps of: (1) determining when absolute pitch, roll and yaw rate are each below a predetermined value; (2) stopping a pre-existing aircraft acceleration or deceleration such that the aircraft airspeed moves toward an airspeed reference in response to said step (1); and (3) maintaining the aircraft airspeed at the airspeed reference. 2. A method as recited in claim 1, wherein said step (1) further comprises determining whether airspeed is greater than a predetermined value. 3. A method as recited in claim 1, wherein said step (1) further comprises determining whether an absolute bank angle is below a predetermined bank value. 4. A method as recited in claim 1, wherein said step (1) further comprises determining whether a pitch attitude is below a predetermined pitch attitude. 5. A method as recited in claim 1, wherein said step (1) further comprises determining whether full primary flight control system mode is available. 6. A method as recited in claim 5, wherein primary flight control system mode is available when a predetermined quantity of sensor data is available to the fly-by-wire system. 7. A method as recited in claim 1, wherein said step (1) occurs at an engagement airspeed other than the airspeed reference. 8. A method as recited in claim 1, further comprising the step of deactivation of the airspeed hold function in response to an absolute pilot longitudinal cyclic stick command is out of detent for a time greater than a predetermined value. 9. A method as recited in claim 1, further comprising the step of deactivation of the airspeed hold function in response to an absolute pilot longitudinal cyclic stick command greater than a predetermined value that is a function of lateral stick displacement. 10. A method as recited in claim 1, further comprising the step of deactivation of the airspeed hold function in response to a longitudinal cyclic rotor command reaches a limit. 11. A method as recited in claim 1, further comprising the step of deactivation of the airspeed hold function in response to an absolute shaped yaw command greater than a predetermined value. 12. A method as recited in claim 11, further comprising the step of: (3) maintaining the aircraft airspeed at the airspeed reference. 13. A method as recited in claim 1, wherein said step (2) is activated in response to maintaining an airspeed at a desired airspeed for a predetermined time period. 14. A method as recited in claim 1, wherein said step (2) is activated in response to maintaining a longitudinal acceleration below a predetermined value. 15. A method as recited in claim 1, wherein said step (2) is activated in response to trimming the aircraft to an accelerating/decelerating maneuver; and waiting until a longitudinal acceleration is below a predetermined value. 16. A method of providing an airspeed hold function for a fly-by-wire system of a rotary-wing aircraft comprising the steps of: (1) calculating an airspeed reference as a function of a rate of change of an aircraft airspeed; and (2) stopping a pre-existing aircraft acceleration or deceleration such that the aircraft airspeed moves toward the airspeed reference. 17. A method as recited in claim 16, wherein said step (2) occurs over a finite amount of time. 18. A method as recited in claim 17, wherein the finite amount of time is defined by a time for a lag output to progress from the pre-existing aircraft acceleration to zero.