METHOD AND SYSTEM FOR DETERMINING ROTOR STATES

1 . A rotor-state determining system for a rotor system, the rotor-state determining system comprising:

a hub attached to a mast;

a rotor blade coupled to the hub;

a first sensor positioned on a first component of the rotor system, wherein the first sensor is isolated from movement of the rotor blade; and

a second sensor positioned on a second component of the rotor system, wherein the second sensor detects movement of the rotor blade.

2 . The rotor-state determining system of claim 1 , comprising:

wherein the first component is the mast; and

wherein the second component is a root end of the rotor blade.

3 . The rotor-state determining system of claim 1 , comprising:

wherein the first component is a non-rotating component of the rotor system.

4 . The rotor-state determining system of claim 1 , comprising:

a flapping hinge positioned between the rotor blade and the hub;

wherein the first component is the hub; and

wherein the second sensor is located outboard of the flapping hinge.

5 . The rotor-state determining system of claim 1 , comprising:

a flexure positioned between the rotor blade and the hub;

wherein the first component is the hub; and

wherein the second component is the rotor blade.

6 . The rotor-state determining system of claim 5 , wherein the second sensor is an accelerometer.

7 . The rotor-state determining system of claim 5 , wherein the second sensor is an angular rate sensor.

8 . The rotor-state determining system of claim 5 , comprising:

a third sensor disposed on the mast;

wherein the first sensor is an angular rate sensor;

wherein the first component is the hub; and

wherein the second and third sensors are accelerometers.

9 . The rotor-state determining system of claim 1 , comprising:

a lead-lag hinge, a flapping hinge, and a feathering hinge positioned between the hub and the rotor blade;

a third sensor disposed outboard of the flapping hinge;

a fourth sensor disposed on the rotor blade;

wherein the first component is the hub; and

wherein the second component is outboard of the hub and inboard of the flapping hinge.

10 . A rotor-state determining method for a rotorcraft, the method comprising by a flight control computer:

collecting data from a first sensor positioned on a first component of the rotorcraft, wherein the first sensor is isolated from movement of a rotor blade;

collecting data from a second sensor positioned on a second component of the rotorcraft, wherein the second sensor detects movement of the rotor blade;

filtering the data collected by the first sensor to remove noise from the data collected by the first sensor;

filtering the data collected by the second sensor to remove noise from the data collected by the second sensor;

calculating a difference between the filtered first data and the filtered second data to determine a parameter of the rotor blade; and

taking a corrective action responsive to the parameter of the rotor blade.

11 . The rotor-state determining method of claim 10 , wherein the corrective action comprises at least one of changing a pitch of the rotor blade, changing an amount or direction of cyclic, changing an amount of collective, and changing an rpm of the rotor blade.

12 . The rotor-state determining method of claim 10 , wherein the corrective action comprises an alert.

13 . The rotor-state determining method of claim 10 , comprising:

wherein the first component is a mast of the rotorcraft; and

wherein the second component is the rotor blade.

14 . The rotor-state determining method of claim 10 , wherein the second sensor is located outboard of a flapping hinge.

15 . The rotor-state determining method of claim 10 , comprising:

a flapping hinge positioned between the rotor blade and a hub;

wherein the first component is the hub; and

wherein the second sensor is located outboard of the flapping hinge.

16 . The rotor-state determining method of claim 10 , comprising:

a flexure positioned between the rotor blade and a hub;

wherein the first component is the hub; and

wherein the second component is the rotor blade.

17 . The rotor-state determining method of claim 10 , wherein the parameter of the rotor blade is selected from the group consisting of a flapping parameter, a coning parameter, a feathering parameter, and a lead/lag parameter.

18 . The rotor-state determining method of claim 17 , comprising:

a lead-lag hinge, a flapping hinge, and a feathering hinge positioned between a hub and the rotor blade;

a third sensor disposed outboard of the flapping hinge;

a fourth sensor disposed on the rotor blade;

wherein the first component is the hub; and

wherein the second component is outboard of the hub and inboard of the flapping hinge.

19 . The rotor-state determining method of claim 18 , wherein the parameter of the rotor blade is selected from the group consisting of a flapping parameter, a coning parameter, a feathering parameter, and a lead/lag parameter.

20 . An aircraft comprising a rotor-state determining system, the aircraft comprising:

a fuselage; and

a rotor system secured to the fuselage and comprising:

a hub attached to a mast;

a rotor blade coupled to the hub;

a first sensor positioned on a first component of the rotor system, wherein the first sensor is isolated from movement of the rotor blade; and

a second sensor positioned on a second component of the rotor system, wherein the second sensor detects out of plane movement of the rotor blade.