The Design and Development of an Active Smart Wing Model

1. The Design and Development of an Active Smart Wing Model ATAK Technologies

2. Team Structure • Thomas Ayers Project Leader • Robert Aguirre Senior Testing Research Specialist • Kevin Mackenzie Senior Modeling and Design Specialist • Vu Tran Senior Research Specialist • Dr. R. O. Stearman University of Texas Faculty Consultant

3. Presentation Overview • Project Objectives • Aerodynamic Theory • Model Design • Model Testing Options • Project Accomplishments • Recommended Future Pursuits • Summary • Questions

4. Objectives Theory Model Testing Work Summary Questions Randall Bolding Wrote a master’s thesis in 1978 in which a wing model was used to research the use of a stabilator as an active control to suppress flutter Lockheed Martin Corporation A research project on the benefits that an active wing can provide in contemporary aircraft design Project Background

5. Objectives Theory Model Testing Work Summary Questions At high airspeeds normally latent aerodynamic forces become powerful enough to affect the flow about the airfoil These changes cause torsional moments on the wing Theoretically, the use of active wing control on the leading edge flaps and ailerons can be used in order to better control these latent aerodynamic forces High Airspeed Benefits

6. Objectives Theory Model Testing Work Summary Questions At low speeds airflow about the wing can separate from the wing causing a “stall” In natural flight, resonant flapping is used to sustain flight at low flight speeds Theoretically, oscillating the wings by using the control surfaces would create high lift conditions for short, low airspeed maneuvers Low Airspeed Benefits

7. Objectives Theory Model Testing Work Summary Questions To create an active wing model for the purpose of defining relationships between control surface oscillation and flight performance Project Objective

8. Aerodynamic Theory • Project Objectives • Aerodynamic Theory • Model Design • Model Testing Options • Project Accomplishments • Recommended Future Pursuits • Summary • Questions

9. Desirable Flow Types Attached-flow: Difference of the circulations of the upper and lower boundary layers create a lift force near a quarter chord of the airfoil. (figure a) Detached-vortex-flow: rolled-up leading edge vortices create additional lift. (figure b) [4] • Background • Theory • Model • Testing • Work • Summary • Questions

10. Problems Encountered When a critical angle of attack achieved to create high lift, separated unsteady flow is unavoidable, and the vortices formed become uncontrollable once they leave the body. • Unsteady separation • Vortex shedding • Vortex breakdown • Background • Theory • Model • Testing • Work • Summary • Questions

11. Background Theory Model Testing Work Summary Questions To control separation, essentially the boundary vorticity flux control, a relationship between pressure, inertial, and viscous forces must be utilized. Methods for controlling separation: 1) Control tangential pressure gradient: proper design of airfoil and wing geometry 2) Control skin friction field: modify local skin friction field near critical points 3) Introduce local movable wall: oscillating flaps Separation Control

12. Background Theory Model Testing Work Summary Questions When the boundary layer is already separated, control of its reattachment is also feasible by utilizing unsteady excitations. Example: Small leading-edge oscillating flap was used to forced the shear layer separated from a sharp leading edge to attach to just the upstream of a round trailing edge, hence captured a strong vortex above a two-dimensional airfoil with angle of attack up to 27 degree. Lift was increased by 60%. [4] Reattachment Control

13. Reattachment Control The inviscid vortex method can be used to compare flow patterns with or without leading-edge oscillation Case (a) : leading-edge vortex moves downstream as new vorticies start to form. The leading edge vortex cuts off the trailing edge vortex sheet. The main vortex will eventually shed. Case (b): main vortex is stabilized and stays close to the wing with nearly uniform vorticity distribution [4] • Background • Theory • Model • Testing • Work • Summary • Questions

14. Background Theory Model Testing Work Summary Questions An additional example: Poly Vinylidence Flouride (PVDF) piezoelectric film was used on the surface of a NACA 0012 airfoil to generate surface oscillation through polarization changes in the material [5] Non-oscillated case: Max lift coefficient = 0.72, stall angle = 14 degree Oscillated case: Max lift coefficient = 0.76, stall angle = 15 degree [5] [5] Reattachment Control

15. Background Theory Model Testing Work Summary Questions For a highly swept wing, unsteady surface excitations focus on delaying vortex breakdown, or can be used to maintain highly concentrated and stable leading-edge vortices Schematic of mini-upper wing [4] Reattachment Control

16. Background Theory Model Testing Work Summary Questions Mini-upper Wing: The wing has a larger incidence than the main wing, thus forcing the flow below it to converge. This implies an additional axial acceleration at the vortex core, and therefore delays its burst. However, the applicable angle of attack is limited, due to limitations created by the wing design Reattachment Control

17. Model Design • Project Objectives • Aerodynamic Theory • Model Design • Model Testing Options • Accumulated Project Work • Recommended Future Pursuits • Summary • Questions

18. Background Theory Model Work Summary Questions Hydraulic Actuator Electromechanical Actuator Electric Motor Actuator Designs

19. Objectives Theory Model Testing Work Summary Questions Size of Control System – Electric motor and shaft will be half the size of the previous groups Ease of Operation – Does not require understanding of complex controller Able to Test – By taking wind tunnel dimensions into account when designing we make sure that we will be able to mount the wing in order to obtain Cl and Cd measurements Flexibility – Leading and trailing edge flaps will be able to oscillate. Will be able to control angle of deflection and phase between flaps Benefits of ATAK’s Design

20. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Overall Model Assembly

21. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Wing Spar, Engine and Rods

22. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Gearing Assembly

23. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Bevel Gears

24. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Actuation System – Push/Pull Rods

25. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Actuation System including Control Surfaces

26. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Wing Model Without Modified Control Surfaces

27. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Wing Model With Deflected Control Surfaces

28. Model Design • Objectives • Theory • Model • Testing • Work • Summary • Questions Overall Model Assembly

29. Model Testing Options • Project Objectives • Aerodynamic Theory • Model Design • Model Testing Options • Accumulated Project Work • Recommended Future Pursuits • Summary • Questions

30. Background Theory Model Testing Work Summary Questions Model Testing Goals • Take next step in project development • Obtain and reduce data • Conduct repeated tests to ensure quality data acquired

31. Background Theory Model Testing Work Summary Questions Testing Data Acquisition • Relationship between oscillation frequency and • Variations of coefficient of lift • Pressure distributions over wing • Wing spar strain • Wing tip flutter • Relationships can be used to find optimum frequencies for • Maximizing coefficient of lift • Minimizing wing spar strain • Minimizing wing tip flutter

32. Background Theory Model Testing Work Questions Summary Model Testing Equipment • Smoke wire • Pressure taps • Strain Gauges • Accelerometer

33. Background Theory Model Testing Work Summary Questions Model Testing Suggestions • Modify model as needed • Start testing as soon as possible • Be familiar with theory and equations needed to reduce data

34. Project Accomplishments • Project Objectives • Aerodynamic Theory • Model Design • Optional Testing Procedures • Project Accomplishments • Recommended Future Pursuits • Summary • Questions

35. Project Accomplishments • Objectives • Theory • Model • Testing • Work • Summary • Questions • Project has been advanced over the past four terms • The Active Wing Group (AWG) • Active Wing Technology (AWT) • Active Wing Engineering (AWE) • ATAK Technologies (ATAK)

36. Objectives Theory Model Testing Work Summary Questions Recovered F-111 wing-tail from storage Investigated limit cycle oscillations (LCO) Provided a strong foundation for Summer 2002 project continuation Active Wing Group

37. Objectives Theory Model Testing Work Summary Questions Active Wing Technologies Primarily Research on F-111 • Limit cycle oscillations (LCO) • Increasing lift on fighter wings • Implementation of control surfaces • Digital and analog control systems

38. Objectives Theory Model Testing Work Summary Questions Active Wing Engineering • Researched the aerodynamic theory behind oscillating flaps • Selected actuation system • Constructed model wing with leading edge flaps

39. Objectives Theory Model Testing Work Summary Questions ATAK Technologies • Research Aerodynamic forces involved in active wing technology Control surface effect on lift • Model Design Actuation system Structure design AutoCAD model • Delivered spar design to machinist for construction • Gathered all necessary model materials. • Lab Maintenance Worked to clean WRW 316

40. ATAK Technologies • Objectives • Theory • Model • Testing • Work • Summary • Questions Wing Structure

41. Recommended Future Pursuits • Project Objectives • Aerodynamic Theory • Model Design • Optional Testing Procedures • Project Accomplishments • Recommended Future Pursuits • Summary • Questions

42. Objectives Theory Model Testing Work Summary Questions Complete the construction of the wing model Prepare for experimentation using the model Design testing equipment and conditions Place instruments on model design Use LabView software to coordinate data acquisition Conduct experiments using wing model Reduce acquired data and draw conclusions concerning the relationship between frequencies and the desired characteristics. Recommended Future Pursuits

43. Presentation Summary • Background Information • Project Objectives • Aerodynamic Theory • Modeling and Final Design • Proposed Testing Procedures • Project Accomplishments • Recommended Future Work

44. References [1] Aguirre, Robert, Thomas Ayers, Kevin Mackenzie, and Vu Tran. “Design and Development of an Active Wing Model.” ATAK Technologies, Austin, TX, Mar. 2003. [2] Garret, Carlos, Justin Gray, and Kevin Marr. “Design of an Active Controlled Wing Model Using Flap Oscillation.” AWE Engineering, Austin, TX, Dec. 2002. [3] Fuentes, David, Basil Philips, and Naoki Sato. “Design and Control Modeling of an Active Variable Geometry Wing.” Active Wing Technologies, Austin, TX, Aug. 2003. [4] Wu, J.M., Wu, J.Z., “Vortex Lift at a Very High Angle of Attack with Massively Separated Unsteady Flow,” Fluid Dynamics of High Angle of Attack, R. Kawamura, Y. Aihara ed., Springer-Verlag, Berlin Heidelberg, 1993, pp. 35-63. [5] Kobayakawa, M., Kondo, Y., Suzuki, H., “Airfoil Flow Control at High Angle of Attack by Surface Oscillation,” Fluid Dynamics of High Angle of Attack, R. Kawamura, Y. Aihara ed., Springer-Verlag, Berlin Heidelberg, 1993, pp. 265-273.

45. Questions?