Overview of the Integrated Adaptive Wing Technology Maturation Wind-Tunnel Test Objectives

Outline

(1) Introduction and Background (2) Wind-tunnel Test Article a) Design, modeling, and characterization (3) Test Plan (4) Questions P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 2 / 23

IAWTM Overview

(1) NASA Advanced Air Transport Technology (AATT) project • Higher Aspect Ratio Optimal Wing technical challenge: Enable a 1.5-2X increase in the aspect ratio of a lightweight wing with safe flight control and structures (2) Approach • Cooperative agreement between NASA and Boeing to develop and test control technologies to meet multiple objectives: – Drag optimization – Maneuver load alleviation – Gust load alleviation – Flutter suppression (3) Purpose • Decrease cost of vehicle operation by reducing induced drag and structural weight penalties normally associated with a high-aspect ratio wing P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 3 / 23 IAWTM Overview, cont.

(4) IAWTM vehicle • Aspect ratio 13.5 wing of a modern transport configuration based on the Common Research Model (CRM) • Aspect ratio is a 1.5X increase over the nominal aspect ratio 9 CRM wing (5) Analysis and testing • Full-scale analysis – Evaluation of performance using a high fidelity 6DOF simulation and development of multiobjective control law • Model-scale testing – Wind tunnel test to be conducted at the NASA Langley Transonic Dynamics Tunnel (TDT) – Two phases (open- and closed-loop), each 18 days P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 4 / 23

Test Objectives

(1) Drag optimization at off nominal conditions • Drag measured with balance (5-component) (2) Maneuver load alleviation TDT AOS • Load reduction measured with model strain sensors (3) Gust load alleviation • Gust excitation provided by TDT airstream oscillation system (AOS) • Upstream vane sensor to serve as surrogate LIDAR gust detector for predictive gust load alleviation (4) Active flutter suppression • Modal suppression important at all operating conditions due to low structural stiffness and damping P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 5 / 23

Wind-tunnel Test Article Overview

• Semispan dynamically scaled wing for testing at NASA Transonic Dynamics Tunnel (TDT) – Spar-pod construction (aluminum spar, carbon fiber skins) with flow-through engine nacelle and nonmetric fuselage – 10 active control surfaces and large number of sensors (accelerometers, strain gages, distributed strain sensors, balance, gust vane sensor) • Removable tip ballast designed to lower the flutter frequency and dynamic pressure for AFS testing Source: D. Ortega, Boeing, AWT04 Modal Correlated FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 6 / 23

Spar Design

• Equivalent beam model provided target spanwise bending and torsional stiffness distributions – Modified I-beam cross section developed to improve stiffness matching and remain inside the wing OML – 25 equally distributed spanwise design stations used for stiffness matching, with linear taper between those cross sections • Due to spar length, fabricated in two pieces and permanently bonded and fastened at spar joint P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 7 / 23

Static Aeroelastic Wing Deformation

• Equivalent beam deformations (FEM) for several critical flight conditions illustrate representative static aeroelastic deformation of the model 2.5g FEM 1g FEM 1g OML jig shape spar jig shape OML -1g FEM P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 8 / 23

Balance Adapter Design

• To support both aerodynamic performance data acquisition using a balance and dynamic aeroelastic testing, a balance adapter will be used to engage/disengage the balance on the model load path Shims-off configuration Shims-on configuration P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 9 / 23

Control Surfaces

• 10 trailing edge distributed control surfaces – 3 hydraulically actuated ailerons (faster response) – 7 electric servo-actuated miniplain flaps (slower response) P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 10 / 23

Sensors

• Sensors: 3 triaxial and 13 single axis accelerometers, 10 full-bridge strain gages, Q-flex inclinometer, 8 balance-based loads, gust vane sensor Accelerometers Strain gages P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 11 / 23

Wind-tunnel Test Article

Model Preparation Area Source: NASA P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 12 / 23

Pretest Analytical Work

(1) Tools • FUN3D • VSPAERO • MSC Nastran • Simulink • ZAERO (2) Studies • Gust vane modeling • Control surface aerodynamic database • Flutter boundary • Development of ASE models • Buffet onset • Critical Mach number • Wind tunnel wall interference modeling • Control surface reversal boundary • Closed-loop controllers developed by Boeing and NASA P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 13 / 23

Model Characterization

(1) Ground vibration test • TDT model preparation area, mounted to backstop • TDT test section, mounted to tunnel sidewall support (2) Measured mass properties database (3) Actuator checkout and performance characterization (4) Static load testing • Strain gage calibration, model validation, digital image correlation checkout P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 14 / 23

Backstop GVT

(1) GVT in TDT MPA of three model configurations • Shims-off • Shims-on • Shims-on, ballast-on (2) Several other parameters were varied during testing to assess modal impact • Control surfaces taped OR actuators on • Skin pods untaped OR taped • Shaker OR hammer excitation (3) Equipment • 3x shakers • Impact hammer • > 100 externally-instrumented accelerometer signals Source: NASA P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 15 / 23

Test Section GVT

• After MPA GVT, most significant structural uncertainty is associated with test section boundary condition, with the test article mounted to the sidewall support Source: NASA P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 16 / 23

FEM Normal Modes Comparison

Shims-off configuration, first vertical bending AWT03, 3.573 Hz AWT04, 3.635 Hz AWT05, 3.644 Hz (3.59 Hz test) Source: D. Ortega, Boeing, AWT03 ASE State-Space Modeling , AWT04 Modal Correlated FEM Review , and AWT05 GVT2 in TDT Modal Correlation FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 17 / 23

FEM Normal Modes Comparison

Shims-off configuration, vehicle pitch AWT03, 7.308 Hz AWT04, 7.674 Hz AWT05, 8.488 Hz (8.78 Hz test) Source: D. Ortega, Boeing, AWT03 ASE State-Space Modeling , AWT04 Modal Correlated FEM Review , and AWT05 GVT2 in TDT Modal Correlation FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 18 / 23

NASA Langley Transonic Dynamics Tunnel

• TDT is a unique WT facility that contains several features essential for aeroservoelastic testing – Configured to perform higher risk aeroelastic testing • Direct view of the test article from the control room • Bypass valves that can rapidly lower test section dynamic pressure in the case of an instability • Downstream safety screen to protect the drive motor and fan blades – Hydraulic power supply for the test article available for high speed actuation of control surfaces – Airstream oscillation system with upstream gust vanes to provide gust excitation for GLA testing – Heavy gas (R134a) test medium to match fluid-structure scaling parameters important to aeroelastic response and flutter Source: NASA P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 19 / 23

Planned Test Points and Predicted Flutter Boundaries

Phase 1 • Phase 1 testing will target open-loop aerodynamic and aeroelastic characterization – Each series corresponds to a different initial wind-off pressure – At each point, control surface static schedules and dynamic sweeps will be conducted for aerodynamic model verification and updating • Data is also planned to be acquired at several test article AOAs and multiple surfaces active for interaction testing • Flutter mechanism for shims-off and shims-on configurations is a hump mode, and since the as-built model structural damping is quite low, real-time monitoring will be essential P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 20 / 23

Summary

• IAWTM wind-tunnel test article has been designed to meet test objectives targeting active control techniques for a highly flexible, high aspect ratio, wing – Overview of model scaling, structural design, instrumentation, and control systems demonstrates the complexity of the test article • Significant pretest analysis and characterization work has been completed in preparation for Phase 1 open-loop testing • Lessons learned and data acquired during the preparation and conduct of the wind tunnel experiment will be directly applicable to improvements in aeroelastic modeling and testing of high aspect ratio, highly flexible wings P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 21 / 23

Acknowledgments

Special thanks to IAWTM team members from Boeing Research & Technology, NextGen Aeronautics, NASA Langley Research Center, NASA Ames Research Center, and NASA Armstrong Flight Research Center P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 22 / 23

Questions?

P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024 23 / 23

Example Pretest Flutter Analysis, M = 0 . 85

∞ Shims-off configuration • Hump flutter mechanism occurs at q ≈ 212 psf with a flutter frequency of ∞ f ≈ 7 . 35 Hz P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Example Pretest Flutter Analysis, M = 0 . 70

∞ Shims-on, ballast-on configuration • Hard flutter mechanism occurs at q ≈ 170 psf with a flutter frequency of ∞ f ≈ 6 . 01 Hz P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Backstop GVT

Source: J. Templeton, NASA LaRC, GVT Test Plan P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Backstop Model Modes Pre- and Post-FEM Scrub

Shims-off configuration • Pre- and post-FEM scrub tables summarizing frequency error and cross-orthogonality between FEM and test modes – Scrub led to significant improvements in XOR and frequency matching • Planned configuration for drag optimization testing Source: D. Ortega, Boeing, AWT04 Modal Correlated FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Backstop Model Modes Pre- and Post-FEM Scrub

Shims-on configuration • Planned configuration for MLA and GLA testing Source: D. Ortega, Boeing, AWT04 Modal Correlated FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Backstop Model Modes Pre- and Post-FEM Scrub

Shims-on, ballast-on configuration • Planned configuration for flutter suppression testing Source: D. Ortega, Boeing, AWT04 Modal Correlated FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Test Section Model Modes, Configurations 1 and 2

Backstop GVT-calibrated model Source: D. Ortega, Boeing, AWT04 Modal Correlated FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

FEM Normal Modes Comparison

Shims-off configuration, first fore-aft bending AWT03, 7.730 Hz AWT04, 8.276 Hz AWT05, 8.059 Hz (7.89 Hz test) Source: D. Ortega, Boeing, AWT03 ASE State-Space Modeling , AWT04 Modal Correlated FEM Review , and AWT05 GVT2 in TDT Modal Correlation FEM Review P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Planned Wind-tunnel Test Conditions

P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Simulated Full-Scale Fuel Burn Minimization Controller

• M = 0 . 85 , q = 230 psf ∞ ∞ P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Simulated Model-Scale Drag Minimization Controller

• M = 0 . 85 , q = 230 psf for shims-off configuration ∞ ∞ P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024

Simulated Model-Scale Gust Load Alleviation Controller

• M = 0 . 70 , q = 190 psf for shims-on configuration ∞ ∞ P.S. Heaney, NASA LaRC IAWTM SciTech 2024 January 12, 2024