Variable camber trim units, aircraft comprising the same, and associated methods of operation

1. A variable camber trim unit, comprising:

a housing;

an input gear, rotatably supported by the housing; and

an output gear, rotatably supported by the housing;

wherein:

the variable camber trim unit is selectively configurable to one of a coupled configuration or a decoupled configuration;

when the variable camber trim unit is in the coupled configuration, rotation of the input gear relative to the housing causes rotation of the output gear relative to the housing; and

when the variable camber trim unit is in the decoupled configuration, rotation of the input gear relative to the housing does not cause rotation of the output gear relative to the housing, and the output gear is capable of at least 5° and no more than 15° of rotation relative to the housing.

2. The variable camber trim unit according to claim 1 , further comprising:

an input idler gear, rotatably supported by the housing, meshed with the input gear, and comprising an input-idler-gear interior splined surface;

an output idler gear, rotatably supported by the housing, coaxial with the input idler gear, meshed with the output gear, and comprising an output-idler-gear interior splined surface;

a shaft, translationally supported within the housing, coaxial with the input idler gear and with the output idler gear, and comprising a first exterior splined surface, having a first-exterior-splined-surface maximum diameter, and a second exterior splined surface, having a second-exterior-splined-surface maximum diameter;

an anchor, positioned within the housing and comprising an anchor interior splined surface, coaxial with the input idler gear and with the output idler gear;

wherein:

when the variable camber trim unit is in the coupled configuration, the shaft is positioned within the housing, such that:

the first exterior splined surface of the shaft is engaged with the input-idler-gear interior splined surface;

the first exterior splined surface of the shaft is disengaged from the anchor interior splined surface; and

the second exterior splined surface of the shaft is engaged with the output-idler-gear interior splined surface; and

when the variable camber trim unit is in the decoupled configuration, the shaft is positioned within the housing, such that:

the first exterior splined surface of the shaft is disengaged from the input-idler-gear interior splined surface;

the first exterior splined surface of the shaft is engaged with the anchor interior splined surface; and

the second exterior splined surface of the shaft is engaged with the output-idler-gear interior splined surface.

3. The variable camber trim unit according to claim 2 , further comprising an actuator, supported by the housing and configured to selectively translate the shaft from a retracted position, in which the first exterior splined surface is disengaged from the anchor interior splined surface, to an extended position, in which the first exterior splined surface is engaged with the anchor interior splined surface.

4. The variable camber trim unit according to claim 3 , further comprising a shaft spring, positioned within the housing and biasing the shaft toward the retracted position.

5. The variable camber trim unit according to claim 3 , wherein:

the actuator comprises a cylinder and an actuator piston, positioned within the cylinder and operatively engaged with the shaft; and

when the cylinder is pressurized, the actuator piston translates toward the anchor interior splined surface and causes the shaft to translate toward the extended position.

6. The variable camber trim unit according to claim 5 , further comprising a pressure compensation chamber;

wherein:

the housing comprises an internal volume, within which the shaft is positioned;

the pressure compensation chamber is in fluidic communication with the internal volume; and

when the actuator piston causes the shaft to translate toward the extended position, fluid from the internal volume flows into the pressure compensation chamber.

7. The variable camber trim unit according to claim 6 , wherein the pressure compensation chamber comprises a chamber piston and a chamber spring, biasing the chamber piston toward the internal volume.

8. The variable camber trim unit according to claim 2 , wherein the anchor comprises:

a body, coaxial with the shaft and comprising the anchor interior splined surface; and

anchor springs, engaged between the body and the housing and rotationally biasing the body toward a rotational default position.

9. The variable camber trim unit according to claim 2 , wherein:

the anchor interior splined surface comprises an anchor-interior-splined-surface first end and an anchor-interior-splined-surface second end;

the input idler gear is closer to the anchor-interior-splined-surface first end than to the anchor-interior-splined-surface second end; and

splines of the anchor interior splined surface are tapered at the anchor-interior-splined-surface first end.

10. The variable camber trim unit according to claim 2 , wherein:

each spline of the input-idler-gear interior splined surface comprises a distal end, facing away from the output idler gear; and

the distal end is tapered.

11. The variable camber trim unit according to claim 2 , wherein:

each spline of the first exterior splined surface comprises a first-exterior-spline first end and a first-exterior-spline second end, spaced apart from each other;

the first-exterior-spline first end is tapered; and

the first-exterior-spline second end is tapered.

12. The variable camber trim unit according to claim 2 , wherein:

the input idler gear further comprises an axial bore;

the shaft extends through the axial bore;

the axial bore comprises a distal region, having a distal-region diameter, and a proximal region, having a proximal-region diameter;

the output idler gear is closer to the proximal region than to the distal region;

the input-idler-gear interior splined surface extends along only the distal region of the axial bore; and

when the variable camber trim unit is in the decoupled configuration, the second exterior splined surface extends within the proximal region of the axial bore.

13. The variable camber trim unit according to claim 12 , wherein the proximal-region diameter is greater than the second-exterior-splined-surface maximum diameter.

14. The variable camber trim unit according to claim 12 , wherein the proximal-region diameter is greater than the distal-region diameter.

15. The variable camber trim unit according to claim 12 , wherein the first-exterior-splined-surface maximum diameter is identical to the second-exterior-splined-surface maximum diameter.

16. The variable camber trim unit according to claim 12 , wherein:

the shaft further comprises a collar;

when the variable camber trim unit is in the coupled configuration, the collar engages the output idler gear; and

when the variable camber trim unit is in the decoupled configuration, the collar is positioned within the proximal region.

17. The variable camber trim unit according to claim 2 , wherein:

the shaft further comprises a collar; and

when the variable camber trim unit is in the coupled configuration, the collar engages the output idler gear.

18. The variable camber trim unit according to claim 2 , further comprising a distal proximity sensor, supported by the housing and configured to sense when the shaft is less than a threshold distance away from the distal proximity sensor, wherein, when the shaft is less than the threshold distance away from the distal proximity sensor, the first exterior splined surface is engaged with the anchor interior splined surface and is disengaged from the input-idler-gear interior splined surface.

19. The variable camber trim unit according to claim 2 , further comprising a proximal proximity sensor, supported by the housing and configured to sense when the shaft is less than a threshold distance away from the proximal proximity sensor, wherein, when the shaft is less than the threshold distance away from the proximal proximity sensor, the first exterior splined surface is disengaged from the anchor interior splined surface and is engaged with the input-idler-gear interior splined surface.

20. A method of trimming flight-control surfaces, the method comprising configuring the variable camber trim unit according to claim 1 to the coupled configuration and configuring the variable camber trim unit to the decoupled configuration.

21. An aircraft, comprising:

a fuselage; and

a wing, supported by the fuselage and comprising:

an inboard flight-control surface, movable relative to the fuselage;

an outboard flight-control surface, movable relative to the fuselage; and

the variable camber trim unit according to claim 1 ;

wherein:

when the variable camber trim unit is in the coupled configuration, the outboard flight-control surface is coupled to the inboard flight-control surface, such that when the inboard flight-control surface is moved relative to the fuselage, the outboard flight-control surface also is moved relative to the fuselage; and

when the variable camber trim unit is in the decoupled configuration, the outboard flight-control surface is decoupled from the inboard flight-control surface, such that moving the inboard flight-control surface relative to the fuselage does not cause the outboard flight-control surface to move relative to the fuselage.