Two-axis gimbal mounted propulsion systems for aircraft

1. A propulsion assembly for an aircraft, the propulsion assembly comprising:

a housing;

a gimbal coupled to the housing and configured to tilt relative to the housing about 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 with a direction;

wherein, the first axis of the gimbal is orthogonal to the second axis of the gimbal; and

wherein, actuation of the gimbal tilts the propulsion system including the electric motor and the rotor assembly relative to the housing to change the rotational plane of the rotor assembly relative to the housing, thereby controlling the direction of the thrust vector within a thrust vector cone.

2. The propulsion assembly as recited in claim 1 wherein the gimbal further comprises an outer gimbal member and an inner gimbal member, the outer gimbal member coupled to the housing and operable to tilt about the first axis, the inner gimbal member coupled to the outer gimbal member and operable to tilt about the second axis; and

wherein the propulsion system is coupled to the inner gimbal member.

3. The propulsion assembly as recited in claim 2 further comprising a first actuator coupled between the housing and the outer gimbal member, the first actuator operable to tilt the outer gimbal about the first axis.

4. The propulsion assembly as recited in claim 3 further comprising a second actuator coupled between the housing and the inner gimbal member, the second actuator operable to tilt the inner gimbal about the second axis.

5. The propulsion assembly as recited in claim 1 wherein the first and second axes pass through the propulsion system.

6. The propulsion assembly as recited in claim 1 wherein the propulsion system has a center of mass and wherein the first and second axes pass through the center of mass.

7. The propulsion assembly as recited in claim 1 wherein the propulsion system has a center of mass and wherein the first and second axes pass through the propulsion system at a location within a predetermined distance of the center of mass.

8. The propulsion assembly as recited in claim 1 wherein the propulsion system has a center of mass in hover and wherein the first and second axes pass through the center of mass in hover.

9. The propulsion assembly as recited in claim 1 wherein the propulsion system has a center of mass in hover and wherein the first and second axes pass through the propulsion system at a location within a predetermined distance of the center of mass in hover.

10. The propulsion assembly as recited in claim 1 wherein the propulsion system has a center of mass and a center of mass in hover and wherein the first and second axes pass through the propulsion system at a location between the center of mass and the center of mass in hover.

11. The propulsion assembly as recited in claim 1 wherein a maximum angle of the thrust vector cone is between about ten degrees and about thirty degrees.

12. The propulsion assembly as recited in claim 1 wherein a maximum angle of the thrust vector cone is between about fifteen degrees and about twenty-five degrees.

13. The propulsion assembly as recited in claim 1 wherein a maximum angle of the thrust vector cone is about twenty degrees.

14. An aircraft comprising:

an airframe;

a distributed thrust array attached to the airframe, the distributed 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 configured to tilt relative to the housing about 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 with a direction;

wherein, the first axis of the gimbal is orthogonal to the second axis of the gimbal; and

wherein, actuation of each gimbal is operable to tilt the respective propulsion system including the electric motor and the rotor assembly relative to the airframe to change the rotational plane of the respective rotor assembly relative to the airframe, thereby controlling the direction of the respective thrust vector within a thrust vector cone.

15. The aircraft as recited in claim 14 further comprising a thrust-borne flight mode and a wing-borne flight mode.

16. The aircraft as recited in claim 14 wherein the distributed thrust array further comprises a two dimensional thrust array.

17. The aircraft as recited in claim 14 wherein the distributed thrust array further comprises at least four propulsion assemblies.

18. The aircraft as recited in claim 14 wherein each propulsion assembly further comprises a line replaceable propulsion unit.

19. The aircraft as recited in claim 14 wherein the distributed thrust array is operable to provide yaw authority in hover responsive to differential thrust vectoring.

20. The aircraft as recited in claim 14 wherein the distributed thrust array is operable to provide lateral movement authority, longitudinal movement authority and combinations thereof in hover responsive to thrust vectoring.