Tunable blade assembly, a blade assembly, and a method of controlling vibration

1. A tunable blade assembly for a flight vehicle, the tunable blade assembly comprising:

a hub rotatable about a central axis;

a blade extending along a longitudinal axis between a root end and a tip end, with the tip end spaced from the hub, wherein the longitudinal axis is transverse to the central axis, wherein the blade is coupled to the hub at the root end such that the blade is rotatable concurrently with the hub and rotation of the blade generates vibrations in the blade, wherein the blade defines a cavity spaced from the tip end;

a tunable control assembly including a mass adjustable inside of the cavity of the blade to reduce the vibrations in the blade; and

wherein:

the mass is adjustable by increasing a weight of the mass inside of the cavity to a first adjusted mass; or

the mass is adjustable by decreasing the weight of the mass inside of the cavity to a second adjusted mass.

2. The tunable blade assembly as set forth in claim 1 wherein:

the tunable control assembly includes a first wall disposed inside of the cavity to define a first boundary of the cavity that houses the mass;

the tunable control assembly includes a second wall disposed inside of the cavity to define a second boundary of the cavity that houses the mass; and

the first wall and the second wall are spaced apart from each other to define a containment area, and the mass is disposed between the first wall and the second wall in the containment area.

3. The tunable blade assembly as set forth in claim 2 wherein the first wall is stationary, and the second wall is movable relative to the first wall to change a volume of the containment area to accommodate the first adjusted mass or the second adjusted mass.

4. The tunable blade assembly as set forth in claim 3 wherein:

the tunable control assembly includes an actuator having a connector coupled to the second wall; and

the actuator is configured to operate the connector to move the second wall inside of the cavity to change the volume of the containment area.

5. The tunable blade assembly as set forth in claim 2 wherein the weight of the mass is adjustable to define an adjustable mass.

6. The tunable blade assembly as set forth in claim 5 wherein:

the adjustable mass is formed of a liquid fluid;

the tunable control assembly includes a pump coupled to the cavity via a first fluid line and the pump is configured to adjust the liquid fluid to the first adjusted mass;

the tunable control assembly includes a reservoir spaced apart from the blade; and

the reservoir is configured to store excess liquid fluid away from the cavity.

7. The tunable blade assembly as set forth in claim 6 wherein:

the tunable control assembly includes an inlet in fluid communication with the pump and an outlet in fluid communication with the reservoir; and

the pump and the reservoir are in fluid communication with each other such that the pump pumps the liquid fluid from the reservoir, through the first fluid line, and into the containment area of the cavity via the inlet.

8. The tunable blade assembly as set forth in claim 7 wherein:

the cavity extends along the longitudinal axis between a proximal end and a distal end;

the proximal end is disposed closer to the root end of the blade than the proximal end is to the tip end of the blade;

the distal end is disposed closer to the tip end of the blade than the distal end is to the root end of the blade; and

the outlet is spaced apart from the inlet and the outlet is in fluid communication with the containment area of the cavity.

9. The tunable blade assembly as set forth in claim 8 wherein:

the inlet is defined through the second wall; and

the outlet is defined through the first wall.

10. The tunable blade assembly as set forth in claim 1 wherein:

the mass is adjustable by moving the mass toward the tip end of the blade; or

the mass is adjustable by moving the mass toward the root end of the blade.

11. The tunable blade assembly as set forth in claim 1 wherein:

the blade includes a leading edge and a trailing edge spaced apart from each other relative to a chord axis that is transverse to the longitudinal axis; and

the blade includes a spar having the cavity disposed in the spar.

12. A tunable blade assembly for a flight vehicle, the tunable blade assembly comprising:

a hub rotatable about a central axis;

a blade extending along a longitudinal axis between a root end and a tip end, with the tip end spaced from the hub, wherein the longitudinal axis is transverse to the central axis, wherein the blade is coupled to the hub at the root end such that the blade is rotatable concurrently with the hub and rotation of the blade generates vibrations in the blade, wherein the blade defines a cavity spaced from the tip end;

a tunable control assembly including a mass adjustable inside of the cavity of the blade to reduce the vibrations in the blade; and

wherein:

the tunable control assembly includes a first wall disposed inside of the cavity to define a first boundary of the cavity that houses the mass;

the tunable control assembly includes a second wall disposed inside of the cavity to define a second boundary of the cavity that houses the mass;

the first wall and the second wall are spaced apart from each other to define a containment area, and the mass is disposed between the first wall and the second wall in the containment area; and

the first wall and the second wall are movable relative to each other to change a location of the first boundary and a location of the second boundary inside of the cavity to change a volume of the containment area to accommodate a first adjusted mass or a second adjusted mass.

13. The tunable blade assembly as set forth in claim 12 wherein:

the tunable control assembly includes a first actuator having a first connector coupled to the first wall;

the first actuator is configured to operate the first connector to move the first wall inside of the cavity to change the volume of the containment area;

the tunable control assembly includes a second actuator having a second connector coupled to the second wall; and

the second actuator is configured to operate the second connector to move the second wall inside of the cavity to change the volume of the containment area.

14. The tunable blade assembly as set forth in claim 13 wherein:

the tunable control assembly includes a sensor coupled to the blade;

the tunable control assembly includes a controller in communication with the sensor, the first actuator, and the second actuator; and

the controller is configured to activate and deactivate the first actuator and/or the second actuator based on information obtained from the sensor.

15. The tunable blade assembly as set forth in claim 12 wherein:

the mass is adjustable by increasing the mass inside of the cavity to the first adjusted mass; or

the mass is adjustable by decreasing the mass inside of the cavity to the second adjusted mass.

16. The tunable blade assembly as set forth in claim 12 wherein:

the mass is adjustable by moving the mass toward the tip end of the blade; or

the mass is adjustable by moving the mass toward the root end of the blade.

17. A tunable blade assembly for a flight vehicle, the tunable blade assembly comprising:

a hub rotatable about a central axis;

a blade extending along a longitudinal axis between a root end and a tip end, with the tip end spaced from the hub, wherein the longitudinal axis is transverse to the central axis, wherein the blade is coupled to the hub at the root end such that the blade is rotatable concurrently with the hub and rotation of the blade generates vibrations in the blade, wherein the blade includes a spar, the spar having a cavity spaced from the tip end;

a tunable control assembly including a mass adjustable inside of the cavity of the blade to reduce the vibrations in the blade; and

wherein:

the mass includes a first mass portion formed of a fixed mass having a constant weight and a second mass portion formed of a fixed mass having a constant weight;

the tunable control assembly includes a first actuator having a first connector coupled to the first mass portion, and the first actuator is configured to operate the first connector to move the first mass portion inside of the cavity axially relative to the longitudinal axis between the root end and the tip end; and

the tunable control assembly includes a second actuator having a second connector coupled to the second mass portion, and the second actuator is configured to operate the second connector to move the second mass portion inside of the cavity axially relative to the longitudinal axis between the root end and the tip end.

18. The tunable blade assembly as set forth in claim 17 wherein the first mass portion and the second mass portion are movable concurrently with each other or movable independently of each other via operation of the first actuator and the second actuator respectively.

19. The tunable blade assembly as set forth in claim 17 wherein:

the first mass portion is adjustable by moving the first mass portion toward the tip end of the blade; or

the first mass portion is adjustable by moving the first mass portion toward the root end of the blade.

20. The tunable blade assembly as set forth in claim 17 wherein:

the second mass portion is adjustable by moving the second mass portion toward the tip end of the blade; or

the second mass portion is adjustable by moving the second mass portion toward the root end of the blade.