Aircraft having redundant directional control
An aircraft has an airframe with a two-dimensional distributed thrust array attached thereto having a plurality of propulsion assemblies that are independently controlled by a flight control system. Each propulsion assembly includes a housing with a gimbal coupled thereto that is operable to tilt about first and second axes responsive to first and second actuators. A propulsion system is coupled to and operable to tilt with the gimbal. The propulsion system includes an electric motor having an output drive and a rotor assembly having a plurality of rotor blades that rotate in a rotational plane to generate thrust having a thrust vector. Responsive to a thrust vector error of a first propulsion assembly, the flight control system commands at least a second propulsion assembly, that is symmetrically disposed relative to the first propulsion assembly, to counteract the thrust vector error, thereby providing redundant directional control for the aircraft.
1. An aircraft having redundant directional control, the aircraft comprising:
an airframe;
a two-dimensional distributed thrust array attached to the airframe, the thrust array including a plurality of propulsion assemblies; and
a flight control system operable to independently control each of the propulsion assemblies;
each propulsion assembly comprising:
a housing;
a gimbal coupled to the housing and operable to tilt about first and second axes;
first and second actuators operable to tilt the gimbal respectively about the first and second axes; and
a propulsion system coupled to and operable to tilt with the gimbal, the propulsion system including an electric motor having an output drive and a rotor assembly having a plurality of rotor blades, the rotor assembly rotatable with the output drive of the electric motor in a rotational plane to generate thrust having a thrust vector;
wherein, responsive to a thrust vector error of a first propulsion assembly, the flight control system commands at least a second propulsion assembly that is symmetrically disposed relative to the first propulsion assembly to counteract the thrust vector error, thereby providing redundant directional control for the aircraft.
2. The aircraft as recited in claim 1 wherein the flight control system further comprises a redundant flight control system.
3. The aircraft as recited in claim 1 wherein the flight control system further comprises a triply redundant flight control system.
4. The aircraft as recited in claim 1 wherein the commands of the flight control system to the second propulsion assembly are selected from the group consisting of tilting the second propulsion assembly about the first axis, tilting the second propulsion assembly about the second axis, changing an operating speed of the rotor assembly of the second propulsion assembly and combinations thereof.
5. The aircraft as recited in claim 1 wherein the thrust vector error of the first propulsion assembly further comprises an actuator fault in the first propulsion assembly.
6. The aircraft as recited in claim 5 wherein the actuator fault in the first propulsion assembly further comprises a static actuator fault causing the propulsion system of the first propulsion assembly to cease tilting about one axis and wherein the flight control system commands the second propulsion assembly to counteract the single axis static actuator fault.
7. The aircraft as recited in claim 5 wherein the actuator fault in the first propulsion assembly further comprises a static actuator fault causing the propulsion system of the first propulsion assembly to cease tilting about both axes and wherein the flight control system commands the second propulsion assembly to counteract the two-axis static actuator fault.
8. The aircraft as recited in claim 5 wherein the actuator fault in the first propulsion assembly further comprises a dynamic actuator fault causing the propulsion system of the first propulsion assembly to tilt uncontrolled about one axis and wherein the flight control system commands the second propulsion assembly to counteract the single axis dynamic actuator fault.
9. The aircraft as recited in claim 5 wherein the actuator fault in the first propulsion assembly further comprises a dynamic actuator fault causing the propulsion system of the first propulsion assembly to tilt uncontrolled about both axes and wherein the flight control system commands the second propulsion assembly to counteract the two-axis dynamic actuator fault.
10. The aircraft as recited in claim 1 wherein, responsive to the thrust vector error of the first propulsion assembly, the flight control system commands at least two other propulsion assemblies to counteract the thrust vector error, thereby providing redundant directional control for the aircraft.
11. The aircraft as recited in claim 1 wherein, responsive to the thrust vector error of the first propulsion assembly, the flight control system commands the aircraft to land at a predetermined location.
12. The aircraft as recited in claim 1 wherein, responsive to the thrust vector error of the first propulsion assembly, the flight control system commands the aircraft to perform an emergency landing.
13. The aircraft as recited in claim 1 wherein, responsive to the thrust vector error of the first propulsion assembly, the flight control system commands the aircraft to continue a current mission.
14. The aircraft as recited in claim 1 wherein, responsive to the thrust vector error of the first propulsion assembly, the flight control system commands the aircraft to adjust a center of mass of a payload relative to the airframe.
15. The aircraft as recited in claim 1 wherein, responsive to the thrust vector error of the first propulsion assembly, the flight control system commands the aircraft to initiate a jettison sequence.
16. The aircraft as recited in claim 1 wherein the plurality of propulsion assemblies further comprises at least four propulsion assemblies forming the two-dimensional thrust array.
17. The aircraft as recited in claim 1 further comprising a thrust-borne flight mode and a wing-borne flight mode.
18. The aircraft as recited in claim 1 wherein the airframe further comprises first and second wings having at least first and second pylons extending therebetween and having a plurality of tail members extending therefrom, each tail member having a control surface.
19. The aircraft as recited in claim 1 further comprising a pod assembly coupled to the airframe.
20. An aircraft having a thrust-borne flight mode and a wing-borne flight mode, the aircraft comprising:
an airframe having first and second wings with at least first and second pylons extending therebetween and with a plurality of tail members extending therefrom;
a pod assembly coupled to the airframe between the first and second pylons;
a two-dimensional distributed thrust array attached to the airframe, the thrust array including at least four line replaceable propulsion units; and
a flight control system operable to independently control each of the propulsion units;
each propulsion unit comprising:
a housing;
a gimbal coupled to the housing and operable to tilt about first and second axes;
first and second actuators operable to tilt the gimbal respectively about the first and second axes; and
a propulsion system coupled to and operable to tilt with the gimbal, the propulsion system including an electric motor having an output drive and a rotor assembly having a plurality of rotor blades, the rotor assembly rotatable with the output drive of the electric motor in a rotational plane to generate thrust having a thrust vector;
wherein, responsive to a thrust vector error of a first propulsion assembly, the flight control system commands at least a second propulsion assembly that is symmetrically disposed relative to the first propulsion assembly to counteract the thrust vector error, thereby providing redundant directional control for the aircraft.