1. A vibration attenuator for a rotor hub of an aircraft, the vibration attenuator comprising:
a weight adapted to be mounted to a non-rotating member of the rotor hub of the aircraft, each weight also being adapted to be rotatable about a weight axis of rotation which is perpendicular to a rotor mast axis; and
a motor configured to rotate the weight about the axis of rotation at a selected speed during operation;
wherein during operation the weight is driven in rotation for creating oscillatory vertical forces along the rotor mast axis for attenuation of rotor-induced vibrations having a selected frequency wherein the weight includes a translatable weight that is configured to be selectively translated on a track that extends radially from the weight axis of rotation.
2. The vibration attenuator according to claim 1, wherein the weight has a center of mass located a selected distance from the weight axis of rotation.
3. The vibration attenuator according to claim 1, wherein the non-rotating member is a standpipe.
4. The vibration attenuator according to claim 1, wherein the weight is selectively movable for changing a distance between a center of mass of the weight and the weight axis of rotation.
5. The vibration attenuator according to claim 1, wherein the weight comprises at least one set of two weights; and
wherein the weights in each set are rotated about the weight axis of rotation in the same direction during operation.
6. The vibration attenuator according to claim 1, wherein the weight comprises at least one set of two weights; and
wherein during operation the weights of each set may be rotated about the axis of rotation at a different rotational speed than the weights of another set, allowing attenuation of vibrations at multiple frequencies.
7. The vibration attenuator according to claim 1, wherein the weight comprises at least one set of two weights; and
wherein during operation the weights of one set may be rotated about the weight axis of rotation in a direction different than the direction of rotation of the weights of another set.
8. The vibration attenuator according to claim 1, wherein the weight comprises at least one set of two weights; and
wherein during operation the weights of each set may be angularly positioned about the axis of rotation relative to each other so as to produce no net force.
9. The vibration attenuator according to claim 1, wherein the motor is an electric motor.
10. The vibration attenuator according to claim 1, wherein the motor is adapted for transferring torque to the weight for rotating the weight during operation.
11. The vibration attenuator according to claim 1, wherein the motor is coupled to the non-rotating member of the rotor hub with a support.
12. The vibration attenuator according to claim 1, wherein the non-rotating member is supported in part by a bearing between the non-rotating member and a rotating rotor mast.
13. The vibration attenuator according to claim 1, wherein the weight comprises at least one set of two weights; and
wherein the each set of weights may be rotated about the weight axis of rotation in a manner that produces a selected phasing of the oscillatory vertical forces.
14. A method of attenuating vibrations in an aircraft having at least one rotor having blades, the rotor having a rotor hub configured for being driven in rotation by a mast about a mast axis of rotation, the method comprising:
(a) locating a rotatable weight in the rotor hub;
(b) rotating each weight at a selected speed about a weight rotation axis that is approximately perpendicular to the mast axis of rotation, the weight being associated with a non-rotating member of the rotor hub; and
(c) controlling the rotation of the rotatable weight for creating oscillatory vertical forces that oppose rotor-induced vibrations having a selected frequency by controlling the translation of the rotatable weight on a track that extends radially from the weight rotation axis.
15. The method according to claim 14, further comprising:
(d) controlling the rotation of the rotatable weight in manner that selectively phases the oscillatory vertical forces relative to the rotor hub.
16. The method according to claim 14, further comprising:
(d) positioning the weight for controlling a distance between a center of mass of the weight and the weight axis of rotation.
17. The method according to claim 14, wherein step (b) comprises rotating the weight at a speed that is a multiple of the product of the number of blades of the rotor multiplied by the rotational speed of the rotor.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1-29. (canceled)
30. A method for forming an aperture in a microfeature workpiece, the method comprising:
positioning the microfeature workpiece between a laser and an electromagnetic radiation sensor;
directing a laser beam from the laser toward the microfeature workpiece to form the aperture in the microfeature workpiece while the microfeature workpiece is positioned between the laser and the electromagnetic radiation sensor; and
sensing the laser beam pass through the microfeature workpiece with the electromagnetic radiation sensor.
31. The method of claim 30, further comprising determining a number of pulses of the laser beam andor an elapsed time to form the aperture.
32. The method of claim 30 wherein the aperture is a test aperture, and wherein the method further comprises:
determining a number of pulses of the laser beam andor an elapsed time to form the test aperture; and
controlling the laser beam based on the determined number of pulses andor the determined elapsed time to form a plurality of production apertures in the microfeature workpiece.
33. The method of claim 30 wherein:
the microfeature workpiece includes a first surface and a second surface opposite the first surface; and
the method further comprises supporting the microfeature workpiece with a workpiece carrier so that a center region of the first surface and a center region of the second surface do not contact the workpiece carrier while directing the laser beam.
34. A system for forming an aperture in a microfeature workpiece, the system comprising:
a laser configured to produce a laser beam along a beam path;
an electromagnetic radiation sensor positioned along the beam path to sense the laser beam; and
a workpiece carrier configured to selectively position the microfeature workpiece in the beam path before the electromagnetic radiation sensor to form the aperture in the microfeature workpiece.
35. The system of claim 34 wherein:
the microfeature workpiece includes a first surface and a second surface opposite the first surface; and
the workpiece carrier is configured to carry the microfeature workpiece without contacting a center region of the first surface and a center region of the second surface of the microfeature workpiece.
36. The system of claim 34 wherein the workpiece carrier is configured to engage a perimeter region of the microfeature workpiece to support the workpiece.
37. The system of claim 34 wherein the workpiece carrier does not obscure the beam path.
38-45. (canceled)
46. A system for forming an aperture in a microfeature workpiece, the system comprising:
a laser configured to produce a laser beam along a beam path;
an electromagnetic radiation sensor positioned along the beam path to sense the laser beam;
a workpiece carrier; and
a controller operably coupled to the laser, the electromagnetic radiation sensor, and the workpiece carrier, the controller having a computer-readable medium containing instructions to perform a method comprising
positioning the microfeature workpiece in the beam path with the workpiece carrier;
directing the laser beam toward the microfeature workpiece to form the aperture in the microfeature workpiece; and
sensing the laser beam pass through the microfeature workpiece with the electromagnetic radiation sensor.
47. The system of claim 46 wherein:
the microfeature workpiece includes a first surface and a second surface opposite the first surface; and
the workpiece carrier is configured to carry the microfeature workpiece without contacting a center region of the first surface and a center region of the second surface of the microfeature workpiece.
48. The system of claim 46 wherein the workpiece carrier is configured to engage a perimeter region of the microfeature workpiece to support the workpiece.
49. The system of claim 46 wherein the computer-readable medium contains instructions to perform the method further comprising determining a number of pulses of the laser beam andor an elapsed time to form the aperture.
50. The system of claim 46 wherein the aperture is a test aperture, and wherein the computer-readable medium contains instructions to perform the method further comprising:
determining a number of pulses of the laser beam andor an elapsed time to form the test aperture; and
controlling the laser beam based on the determined number of pulses andor the determined elapsed time to form a plurality of production apertures in the microfeature workpiece.
51. The method of claim 30 wherein the aperture is a through aperture, and wherein the method further comprises:
determining a number of pulses of the laser beam andor an elapsed time to form the through aperture; and
controlling the laser beam based on the determined number of pulses andor the determined elapsed time to form a plurality of blind apertures in the microfeature workpiece.
52. The method of claim 30 wherein the aperture is a first through aperture, and wherein the method further comprises:
determining a number of pulses of the laser beam andor an elapsed time to form the first through aperture; and
controlling the laser beam based on the determined number of pulses andor the determined elapsed time to form a plurality of second through apertures in the microfeature workpiece.
53. The method of claim 30, further comprising supporting the microfeature workpiece by engaging a perimeter edge of the workpiece with a workpiece carrier.
54. The system of claim 34, further comprising a controller operably coupled to the laser, the electromagnetic radiation sensor, and the workpiece carrier, the controller having a computer-readable medium containing instructions to direct the laser beam toward the microfeature workpiece to form the aperture, and sense the laser beam pass through the microfeature workpiece in real time.
55. The system of claim 34, further comprising a controller operably coupled to the laser, the electromagnetic radiation sensor, and the workpiece carrier, the controller having a computer-readable medium containing instructions to direct the laser beam toward the microfeature workpiece to form the aperture, sense the laser beam pass through the microfeature workpiece, and determine a number of pulses of the laser beam andor an elapsed time to form the aperture.
56. The system of claim 34 wherein the aperture is a test aperture, and wherein the system further comprises a controller operably coupled to the laser, the electromagnetic radiation sensor, and the workpiece carrier, the controller having a computer-readable medium containing instructions to sense the laser beam pass through the microfeature workpiece, determine a number of pulses of the laser beam andor an elapsed time to form the aperture, and control the laser beam based on the determined number of pulses andor the determined elapsed time to form a plurality of production apertures in the microfeature workpiece.
57. The system of claim 46 wherein the workpiece carrier does not obscure the beam path.