1. MODEL DEFORMATION MEASUREMENTS AT NASA WIND TUNNELS USING VIDEOGRAMMETRY

2. AEROELASTIC DEFORMATION MEASUREMENTS
STATE-OF-THE-ART
twist due to aero loads
main wing element
CURRENT CHALLENGES
Components (high lift)
flap, gap, and overhang
Dynamics: up to 1000 Hz

3. WHAT IS VIDEOGRAMMETRY
Photogrammetry + video image processing
Extraction of 2D or 3D info from 2D image data
1 camera  3D rigid body or 2D deformation
(1D must be known for 2D deformation)
2 or more cameras  3D deformation

4. VIDEOGRAMMETRIC TECHNIQUE (VMD)
NTF test section
Looking downstream (+X)
Optical targets
Single-camera photogrammetry
X, Z computed with Y known
video-rate CCD camera
Frame grabber
Auto target location or tracking
3-step calibration procedure Z Y
2.5 m

5. RETROREFLECTIVE TARGETS

6. POLISHED PAINT TARGETS National Transonic Facility
Semispan
POLISHED PAINT TECHNIQUE
inch (1/2 mil) thickness
Feathered edges (no abrupt steps)
10 inch surface roughness
Precision templates 1 2 3 4 5 6 7 X Z
Flow
Full-span

7. CALIBRATION (1) image plane corrections (2) coordinate system
(3) Wind-off polars for angle and X,Z

8. National Transonic Facility Transonic Dynamics Tunnel
FACILITIES
National Transonic Facility
Transonic Dynamics Tunnel
16-Ft Transonic Wind Tunnel
Unitary Plan Wind Tunnel
Ames 12-Ft Pressure Tunnel
Deformation measurements made from subsonic to
supersonic - high lift, cruise, onset of buffet

9. NATIONAL TRANSONIC FACILITY (NTF)
Cryogenic
High Re  high Q
Last 9 tests: deformation

10. VECTOR DISPLACEMENTS 1 2 3 4 5 6 7 X Z
Flow
-5
24

11. CHANGE IN GAP AND OVERHANG DUE TO AERODYNAMIC LOADING

12. DYNAMIC DEFORMATION OF SEMISPAN MODEL
Transonic Dynamics Tunnel
Dq,
deg
Time, sec
Inboard
f = 10.6 Hz
Power
Outboard
f = 10.6 Hz
Power
f, Hz

13. DEFORMATION CONTOURS DZ, inch h = 0 h = 1 D t, sec 0.000 0.017 0.034
0.050
0.067

14. MICRO AIR VEHICLE DEFORMATION CONTOURS. 8 6 4 2 -
DZ, inch

15. 867 FRAMES/SEC DATA ACQUIRED BASIC AERODYNAMIC RESEARCH TUNNEL

16. CONCLUDING REMARKS
Videogrammetry useful for static and dynamic aeroelastic measurements in wind tunnels
Single-camera, single-view technique is workhorse
Useful for a number of tests at NASA facilities
National Transonic Facility (last 9 customer tests)
16-Ft Transonic Wind Tunnel
Transonic Dynamics Tunnel
Unitary Plan Wind Tunnel
Ames 12-Ft Pressure Tunnel
Future efforts
Dynamic measurements up to 1000 Hz
Micro air vehicles
Ultralight and inflatable large space structures
Robustness with and without targets