Method for controlling rotorcraft airfoil to minimize auxiliary rotor noise and enhance rotorcraft performance

Patent metadata

Field	Value
Publication number	US-9725164-B2
Application number	US-201414564437-A
Country	US
Kind code	B2
Filing date	Dec 9, 2014
Priority date	Dec 10, 2013
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A rotorcraft extends longitudinally along a first anteroposterior plane separating a first side from a second side of the rotorcraft. The rotorcraft includes at least one main rotor, an auxiliary rotor, and at least one steerable airfoil. The rotorcraft further includes a processor unit connected to a first measurement system configured to measure a current value of a speed parameter (V) of the rotorcraft and to a second measurement system configured to measure a current value of a power parameter (W) of a power plant of the rotorcraft. The processor unit is configured to adjust the deflection angle of the airfoil as a function of the current speed and power parameter values (V, W) to cause the auxiliary rotor to move towards at least one predetermined operating point which optimizes performance of the rotorcraft and minimizes noise generated by the auxiliary rotor.

First claim

What is claimed is:

1. A method for a rotorcraft, the rotorcraft extending longitudinally along a first anteroposterior plane (P1) separating a first side from a second side of the rotorcraft, the rotorcraft including a main rotor, an auxiliary rotor, and a power plant configured to drive the main rotor and the auxiliary rotor in rotation, wherein the auxiliary rotor is configured to exert lateral thrust in order to control yaw movement of the rotorcraft, the lateral thrust being directed towards the second side in order to counter torque generated by the main rotor on a fuselage of the rotorcraft, the rotorcraft further including a tail fin extending in elevation, wherein the tail fin is provided at least in part with a deflectable airfoil, wherein the airfoil is configured to generate transverse lift as a function of a deflection angle of the airfoil, wherein the airfoil has a trailing edge, wherein the deflection angle of the airfoil is at 0° when the trailing edge is present in a second plane (P2), wherein the deflection angle of the airfoil is negative relative to the second plane (P2) when the trailing edge is directed towards the second side, wherein the deflection angle of the airfoil is positive relative to the second plane (P2) when the trailing edge is directed towards the first side, wherein the deflection angle of the airfoil is controllable at least as a function of a current value of a speed parameter (V) of the rotorcraft and of a current value of a power parameter (W) of the power plant so as to enable the auxiliary rotor to be operated at a predetermined operating point in order to satisfy at least one of a performance target for the rotorcraft and an acoustic target for the auxiliary rotor, the method comprising:
receiving a first power threshold (W1) and a second power threshold (W2), wherein the second power threshold (W2) is greater than the first power threshold (W1);
receiving a first speed threshold (V1), a second speed threshold (V2), a third speed threshold (V3), and a fourth speed threshold (V4), wherein the second speed threshold (V2) is greater than the first speed threshold (V1) which is greater than the fourth speed threshold (V4) which is greater than the third speed threshold (V3);
controlling the deflection angle of the airfoil to reach a first zone (Z1) for which the deflection angle of the airfoil is at a maximum positive threshold angle (δmax) relative to the second plane (P2), the first zone (Z1) being reached by the deflection angle of the airfoil when the current value of the speed parameter (V) of the rotorcraft is lower than the third speed threshold (V3);
controlling the deflection angle of the airfoil to reach a second zone (Z2) for which the deflection angle of the airfoil is at the maximum positive threshold angle (δmax) relative to the second plane (P2), the second zone (Z2) being reached by the deflection angle of the airfoil when the current value of the speed parameter (V) of the rotorcraft is greater than the fourth speed threshold (V4) and lesser than the first speed threshold (V1) and the current value of the power parameter (W) of the power plant is greater than the second power threshold (W2);
controlling the deflection angle of the airfoil to reach a third zone (Z3) for which the deflection angle of the airfoil is substantially 0° relative to the second plane (P2), the third zone (Z3) being reached by the deflection angle of the airfoil when the current value of the speed parameter (V) of the rotorcraft is greater than the second speed threshold (V2) and the current value of the power parameter (W) of the power plant is greater than the second power threshold (W2); and
controlling the deflection angle of the airfoil to reach a fourth zone (Z4) for which the deflection angle of the airfoil is at the minimum negative threshold angle (δmin) relative to the second plane (P2), the fourth zone (Z4) being reached by the deflection angle of the airfoil when the current value of the speed parameter (V) of the rotorcraft is greater than the fourth speed threshold (V4) and the current value of the power parameter (W) of the power plant is lower than the first power threshold (W1).

2. The method according to claim 1 , wherein the speed parameter (V) is selected from a list comprising an air speed and a ground speed.

3. The method according to claim 1 , wherein the power plant includes at least one engine and a main gearbox interposed between the at least one engine and the main rotor, the method further comprising:
selecting the power parameter from a list comprising: total power developed by the at least one engine; total torque generated by the at least one engine; power transmitted to the main gearbox; torque transmitted to the main gearbox; and torque exerted on a mast driving the main rotor.

4. The method according to claim 1 , wherein the second plane (P2) is inclined relative to the first anteroposterior plane (P1) so that the second plane (P2) presents a positive angle relative to the first anteroposterior plane (P1), the trailing edge being directed towards the first side when the airfoil is present in the second plane (P2).

5. The method according to claim 1 , further comprising using a relationship (L) in controlling the deflection of the airfoil, the relationship (L) providing a target angle (δ) for the deflection angle of the airfoil as a function of the speed parameter (V) of the rotorcraft and of the power parameter (W) of the power plant.

6. The method according to claim 5 , wherein the auxiliary rotor has a plurality of blades, wherein the first zone (Z1), the second zone (Z2), the third zone (Z3) and the fourth zone (Z4) define a first sheet, the method further comprising:
determining a maximum angle for the target angle in the application of the relationship (L) to define an upper sheet that is different from the first sheet;
determining a minimum angle for the target angle in the application of the relationship (L) to define a lower sheet that is different from the first sheet and the upper sheet;
measuring the current collective pitch of the blades of the auxiliary rotor;
increasing the deflection angle of the airfoil by causing the deflection angle of the airfoil to move towards the maximum angle so long as the collective pitch is greater than a predetermined setpoint collective pitch, the deflection angle of the airfoil being limited to be less than or equal to the maximum angle;
decreasing the deflection angle of the airfoil by causing the deflection angle of the airfoil to move towards the minimum angle so long as the collective pitch is less than the predetermined setpoint collective pitch, the deflection angle of the airfoil being limited to be greater than or equal to the minimum angle; and
automatically modifying the collective pitch in parallel with modifying the deflection angle of the airfoil.

7. The method according to claim 6 , wherein the rotorcraft includes means for controlling the collective pitch manually, and modification to the deflection angle of the airfoil is inhibited whenever a pilot is operating the control means.

8. A rotorcraft comprising:
a fuselage extending longitudinally along a first anteroposterior plane (P1) separating a first side from a second side of the rotorcraft;
a main rotor;
an auxiliary rotor;
a power plant configured to drive the main rotor and the auxiliary rotor in rotation;
wherein the auxiliary rotor is configured to exert lateral thrust that is controllable in order to control yaw movement of the rotorcraft, the lateral thrust being directed towards the second side in order to counter torque generated by the main rotor on the fuselage of the rotorcraft;
a tail fin extending in elevation and provided at least in part with a deflectable air

Assignees

• Airbus Helicopters

Inventors

• Kelaidis Manousos

Classifications

• B64C27/001 Primary

  Vibration damping devices · CPC title

• B64C2027/8272

  comprising fins, or movable rudders · CPC title

• G05D1/0858

  specially adapted for vertical take-off of aircraft · CPC title

• B64C13/16

  actuated automatically, e.g. responsive to gust detectors · CPC title

• B64C2027/004

  using actuators, e.g. active systems · CPC title