Variable camber continuous aerodynamic control surfaces and methods for active wing shaping control

• US 9,227,721 B1
• Filed: 10/09/2012
• Issued: 01/05/2016
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: USA As Represented By The Administrator Of The NASA
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Nguyen, Nhan T.
• Primary Examiner(s): Dinh, Tien
• Assistant Examiner(s): Green, Richard R
• Application Number:
  US13/648,197
• Time in Patent Office: 1,183 Days
• US Class Current: 1/1
• CPC Class Codes: B64C 2003/147 comprising trailing edges of particular shape
• CPC Class Codes: B64C 2003/445 by changing shape according to the speed, e.g. by morphing
• CPC Class Codes: B64C 3/14 Aerofoil profile
• CPC Class Codes: B64C 3/48 by relatively-movable parts of wing structures
• CPC Class Codes: B64C 3/50 by leading or trailing edge flaps
• CPC Class Codes: B64C 3/52 Warping
• CPC Class Codes: B64C 7/00 Structures or fairings not otherwise provided for
• CPC Class Codes: B64C 9/14 forming slots
• CPC Class Codes: B64C 9/20 by multiple flaps
• CPC Class Codes: B64C 9/24 by single flap
• CPC Class Codes: B64C 9/26 by multiple flaps
• CPC Class Codes: Y02T 50/10 Drag reduction
• CPC Class Codes: Y02T 50/30 Wing lift efficiency
• CPC Class Codes: Y02T 50/40 Weight reduction

Abstract

An aerodynamic control apparatus for an air vehicle improves various aerodynamic performance metrics by employing multiple spanwise flap segments that jointly form a continuous or a piecewise continuous trailing edge to minimize drag induced by lift or vortices. At least one of the multiple spanwise flap segments includes a variable camber flap subsystem having multiple chordwise flap segments that may be independently actuated. Some embodiments also employ a continuous leading edge slat system that includes multiple spanwise slat segments, each of which has one or more chordwise slat segment. A method and an apparatus for implementing active control of a wing shape are also described and include the determination of desired lift distribution to determine the improved aerodynamic deflection of the wings. Flap deflections are determined and control signals are generated to actively control the wing shape to approximate the desired deflection.

Claims

1. A method for implementing control of a wing shape comprising:

identifying or determining a lift distribution for an air vehicle having at least one wing;

determining a deflection of the at least one wing of the air vehicle based at least in part upon the lift distribution;

determining one or more deflections of multiple chordwise flap segments based at least in part upon the deflection of the at least one wing;

allowing for a bending shape change, a twisting shape change, and a camber shape change of the at least one wing using the multiple chordwise flap segments that form individual spanwise flap sections by transmitting one or more flap control signals from a controller to the multiple chordwise flap segments and spanwise flap sections to approximate the wing shape of the at least one wing to the deflection of the at least one wing;

identifying or determining one or more aeroelastic modes for modal suppression; and

determining a deflection of the at least one wing of the air vehicle based at least in part upon the aeroelastic modes.

2. The method of claim 1 comprising:

using the one or more flap control signals to form a piecewise continuous trailing edge for the multiple chordwise flap segments and the spanwise flap sections with or without flexible transition materials in between the multiple chordwise flap segments and in between the spanwise flap sections.

3. The method of claim 1 wherein the act of determining the one or more deflections comprises:

identifying a trim angle of attack;

identifying an induced angle of attack;

identifying an aeroelastic mode for modal suppression;

identifying drag components; and

determining the one or more deflections based further at least in part upon the trim angle of attack, the induced angle of attack, the aeroelastic mode for modal suppression, and the drag components.

4. The method of claim 3 wherein the act of determining the one or more deflections of multiple flap segments comprises:

identifying a flight control model that includes a rigid-body flight dynamic model that correlates a state vector of the air vehicle with a control vector and an aeroservoelastic model that correlates an elastic state vector of the at least one wing with the control vector; and

approximating the deflection of the at least one wing by using a function including multiple coefficients with and without specifications of boundary conditions on the values of the function and its first derivative at the two end points and any point in between.

5. The method of claim 3 wherein the act of determining the one or more deflections of the multiple chordwise flap segments and the spanwise flap sections comprises:

determining the one or more deflections of the control surfaces of the air vehicle using at least some of the multiple coefficients as one or more virtual control variables that approximate shape functions in the flight control model based at least in part upon at least one drag-cognizant cost function including a drag component and an aeroelastic mode to be suppressed.

6. The method of claim 5 wherein the drag component is associated with at least one deflection of the one or more deflections of the multiple flap segments.

7. The method of claim 1 comprising:

determining multiple deflections of the at least one wing of the air vehicle off-line by using one or more models for multiples points in a flight envelope of the air vehicle.

8. The method of claim 7 comprising:

determining a first deflection of the at least one wing in flight by using one or more signals from at least a sensor, wherein the one or more signals from the sensor indicate an elastic state of the at least one wing in flight or a state associated with at least one drag component; and

determining the deflection of the at least one wing by using at least the first deflection and at least some of the multiple deflections.

9. The method of claim 1 wherein the wing comprises an aeroelastic wing and the at least one controller that determines one or more deflections for determining the one or more deflections of the multiple chordwise flap segments and spanwise flap sections to reduce structural loading on the aeroelastic wing during flight maneuvers and gust encounters based at least in part on a cost function that includes a load model, a drag component, and an aeroelastic mode to be suppressed.

10. The method of claim 1 wherein the multiple chordwise flap segments form the individual spanwise flap sections with flexible transition materials in between the individual spanwise flap sections.

11. The method of claim 1 wherein the multiple chordwise flap segments form the individual spanwise flap sections without flexible transition materials in between the individual spanwise flap sections.

12. An apparatus for implementing active control of a wing shape comprising:

at least one controller that is to;

identify or determine a lift distribution for an air vehicle having at least one wing;

determine a deflection of the at least one wing of the air vehicle based at least in part upon the lift distribution;

determine one or more deflections of multiple chordwise flap segments and spanwise flap sections based at least in part upon the deflection of the at least one wing;

allow for a bending shape change, a twisting shape change, and a camber shape change of the at least one wing using the multiple flap segments by transmission of one or more flap control signals from the controller to the multiple chordwise flap segments and the spanwise flap sections to approximate the wing shape of the at least one wing to the deflection of the at least one wing;

identify or determine one or more aeroelastic modes for modal suppression; and

determine a deflection of the at least one wing of the air vehicle based at least in part on the aeroelastic modes.

13. The apparatus of claim 12 comprising:

at least one flap actuator that is to;

receive the one or more flap control signals from the controller to actuate at least one flap segment of the multiple chordwise flap segments and the spanwise flap sections to approximate the wing shape of the at least one wing to the deflection of the at least one wing.

14. The apparatus of claim 13 wherein the at least one flap actuator is further to:

use the one or more flap control signals to form a piecewise continuous trailing edge for the multiple chordwise flap segments and the spanwise flap sections.

15. The apparatus of claim 12 wherein the at least one controller that is to determine the one or more deflections is further to:

identify a trim angle of attack;

identify an induced angle of attack;

identifying an aeroelastic mode for modal suppression;

identifying drag components; and

determine the one or more deflections based further at least in part upon the trim angle of attack, the induced angle of attack, the aeroelastic mode, and the drag components.

16. The apparatus of claim 15 wherein the at least one controller that is to determine the one or more deflections is further to:

identify a flight control model that includes a rigid-body flight dynamic model that correlates a state vector of the air vehicle with a control vector and an aeroservoelastic model that correlates an elastic state vector of the at least one wing with a control vector; and

approximate the deflection of the at least one wing by using a function including multiple coefficients whereby these coefficients act as virtual control variables to approximate shape functions.

17. The apparatus of claim 16 wherein the at least one controller that is to determine the one or more deflections is further to:

determine the one or more deflections of the control surfaces of the air vehicle using at least some of the multiple coefficients as one or more virtual control variables in the flight control model based at least in part upon a cost function including a drag component, and an aeroelastic mode to be suppressed.

18. The apparatus of claim 12 wherein the wing comprises an aeroelastic wing and the at least one controller that determines one or more deflections for determining the one or more deflections of the multiple chordwise flap segments and spanwise flap sections to reduce structural loading on the aeroelastic wing during flight maneuvers and gust encounters based at least in part on a cost function that includes a load model, a drag component, and an aeroelastic mode to be suppressed.